US20040260999A1 - Method and apparatus for reproducing data and method and apparatus for recording and/or reproducing data - Google Patents
Method and apparatus for reproducing data and method and apparatus for recording and/or reproducing data Download PDFInfo
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- US20040260999A1 US20040260999A1 US10/898,043 US89804304A US2004260999A1 US 20040260999 A1 US20040260999 A1 US 20040260999A1 US 89804304 A US89804304 A US 89804304A US 2004260999 A1 US2004260999 A1 US 2004260999A1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
- H03M13/63—Joint error correction and other techniques
- H03M13/6325—Error control coding in combination with demodulation
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/10009—Improvement or modification of read or write signals
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/14—Digital recording or reproducing using self-clocking codes
- G11B20/1403—Digital recording or reproducing using self-clocking codes characterised by the use of two levels
- G11B20/1423—Code representation depending on subsequent bits, e.g. delay modulation, double density code, Miller code
- G11B20/1426—Code representation depending on subsequent bits, e.g. delay modulation, double density code, Miller code conversion to or from block codes or representations thereof
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/18—Error detection or correction; Testing, e.g. of drop-outs
- G11B20/1866—Error detection or correction; Testing, e.g. of drop-outs by interleaving
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
- H03M13/27—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes using interleaving techniques
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
- H03M13/29—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes
- H03M13/2957—Turbo codes and decoding
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
- H03M13/29—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes
- H03M13/2957—Turbo codes and decoding
- H03M13/296—Particular turbo code structure
- H03M13/2972—Serial concatenation using convolutional component codes
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
- H03M13/37—Decoding methods or techniques, not specific to the particular type of coding provided for in groups H03M13/03 - H03M13/35
- H03M13/45—Soft decoding, i.e. using symbol reliability information
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
- H03M13/63—Joint error correction and other techniques
- H03M13/6343—Error control coding in combination with techniques for partial response channels, e.g. recording
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M5/00—Conversion of the form of the representation of individual digits
- H03M5/02—Conversion to or from representation by pulses
- H03M5/04—Conversion to or from representation by pulses the pulses having two levels
- H03M5/14—Code representation, e.g. transition, for a given bit cell depending on the information in one or more adjacent bit cells, e.g. delay modulation code, double density code
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/14—Digital recording or reproducing using self-clocking codes
- G11B20/1403—Digital recording or reproducing using self-clocking codes characterised by the use of two levels
- G11B20/1423—Code representation depending on subsequent bits, e.g. delay modulation, double density code, Miller code
- G11B20/1426—Code representation depending on subsequent bits, e.g. delay modulation, double density code, Miller code conversion to or from block codes or representations thereof
- G11B2020/1434—8 to 9 modulation
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/14—Digital recording or reproducing using self-clocking codes
- G11B20/1403—Digital recording or reproducing using self-clocking codes characterised by the use of two levels
- G11B20/1423—Code representation depending on subsequent bits, e.g. delay modulation, double density code, Miller code
- G11B20/1426—Code representation depending on subsequent bits, e.g. delay modulation, double density code, Miller code conversion to or from block codes or representations thereof
- G11B2020/1446—16 to 17 modulation
Definitions
- This invention relates to a method and apparatus for recording data on a recording medium, a method and apparatus for reproducing data recorded on a recording medium and a method and apparatus for recording and/or reproducing data for a recording medium.
- a recording medium for recording digital data there are known a wide variety of recording mediums of the magnetic, optical or photomagnetic system, such as a hard disc, a so-called DVCR (digital video cassette recorder) or a so-called CD (Compact Disc), DVD (digital versatile disc) and a so-called MO (magneto-optical disc).
- DVCR digital video cassette recorder
- CD Compact Disc
- MO magneticto-optical disc
- the signal recording side for recording signals on a recording medium routinely uses a system of modulation encoding the signal in a pre-set manner to record the resulting modulation-coded signal.
- a modulation-coder performing this modulation coding, routinely is fed with binary signals exempt from various limitations, and outputs binary signals free of various limitations.
- These limitations on the signals include DC free limitations which state that the numbers of “0”s and “1”s be equalized over a sufficient long length of the concatenations of “0”s and “1”s, and the (d, k) limitations which state that the minimum and maximum numbers of consecutive “0”s and “1”s in a code be d and k, respectively.
- the above example indicates that, in converting a bit string free of a limitation is converted into another bit string subjected to a limitation, the total number of the output bits is larger than that of the input bits. If the total number of input bits is K and the total number of output bits is N, the ratio K/N is represented as a code rate R. This code rate R serves as an index indicating the efficiency of the modulation coding. If two or more modulation coders, generating output signals satisfying the same limitations, are compared to one another, a modulation coder having the high code rate R is able to encode more input bits for a given number of output bits than one having the low code rate R. Stated differently, a modulation coder having a high code rate R is able to record more information on a pre-set recording medium than one having a low code rate R.
- the modulation coding may be classified into a block coding system in which input bits are divided into plural blocks of pre-set lengths and output bits generated are divided into plural blocks of pre-set lengths corresponding to the blocks of the input bits, and a variable length coding system, in which encoding units of input bits and output bits associated with the input bits are varied.
- a block coding system in which input bits are divided into plural blocks of pre-set lengths and output bits generated are divided into plural blocks of pre-set lengths corresponding to the blocks of the input bits
- a variable length coding system in which encoding units of input bits and output bits associated with the input bits are varied.
- the so-called 8/9 code or the 16/17 code routinely used for modulation coding, belong to the block coding system
- the so-called (1, 7) RLL code or the (2, 7) RLL code belong to the variable length encoding system.
- a modulation coder has a conversion table as Table 1: TABLE 1 Example of Conversion Table input bits output bits 00 011 01 101 10 111 11 110
- the modulation coder references this conversion table and finds, for each 2-bit input bits, an associated 3-bit output bits, with the output bits being issued as output sequentially.
- a modulation decoder for modulating-decoding the modulation-coded signals has a back-conversion table, as Table 2: TABLE 2 Example of Back-Conversion Table input bit decoded bits 000 01 001 00 010 10 011 00 100 11 101 01 110 11 111 10
- the modulation decoder references this back-conversion table to find and sequentially output 2-bit decoded bits, associated with the 3-bit input bits.
- FIG. 2 shows a typical modulation decoder 160 having at least a ROM (read-only memory) 161 .
- the modulation decoder 160 is fed with an input address signal D 161 to output the contents stored in an address of the ROM 161 corresponding to this input address signal D 161 as a demodulated decoded signal D 162 .
- the input bits are back-converted into decoded bits in accordance with the back-conversion table shown in Table 2, the contents of the decoded bits are stored in addresses of a ROM 161 of the modulation decoder 160 , corresponding to the input bits in Table 2.
- the decoded bits, stored in these addresses, are read out by way of performing the back-conversion.
- FIG. 3 shows a typical modulation decoder 170 at least having a combination circuit 171 .
- the modulation decoder 170 is fed with an input signal D 171 and executes logical operations on the input signal D 171 by the combination circuit 171 to generate a modulated decoded signal D 172 .
- the modulation decoder 170 generates the output bits (b 0 , b 1 ) by the combination circuit 171 corresponding to the following logical equations (1):
- the modulation coder and the modulation decoder are applied to a magnetic recording and/or reproducing apparatus for recording and/or reproducing data on or from a recording medium in accordance with the magnetic recording system
- the recording and/or reproducing apparatus is configured as shown in FIG. 4.
- the magnetic recording and/or reproducing apparatus 200 includes, as a recording system for recording data on a recording medium 250 , an error correction encoder 201 for error correction encoding input data, a modulation encoder 201 , a modulation encoder 202 for modulation encoding the input data, a precoder 203 for filtering input data for compensating its channel characteristics, a write current driver 204 for converting respective bits of the input data into write current values, and a write head 205 for recording data on the recording medium 250 .
- a recording system for recording data on a recording medium 250 includes, as a recording system for recording data on a recording medium 250 , an error correction encoder 201 for error correction encoding input data, a modulation encoder 201 , a modulation encoder 202 for modulation encoding the input data, a precoder 203 for filtering input data for compensating its channel characteristics, a write current driver 204 for converting respective bits of the input data into write current values, and a write head 205 for
- the magnetic recording and/or reproducing apparatus 200 also includes, as a playback system for reproducing data recorded on the recording medium 250 , a readout head 206 for reading out data recording on the recording medium 250 , an equalizer 207 for equalizing the input data, a gain adjustment circuit 208 for adjusting the gain of the input data, an analog/digital converter (A/D converter) 209 for converting analog data into digital data, a timing generating circuit 210 for generating clocks, a gain adjustment control circuit 211 for controlling the gain adjustment circuit 208 , a viterbi decoder 212 for viterbi-decoding the input bits, a modulation decoder 213 for modulation decoding the input data and an error correction decoder 214 for error correction decoding the input data.
- A/D converter analog/digital converter
- the magnetic recording and/or reproducing apparatus 200 performs the following operations:
- the magnetic recording and/or reproducing apparatus 200 When fed with the input data D 201 , the magnetic recording and/or reproducing apparatus 200 applies error correction coding to the input data D 201 , by the error correction encoder 201 , to generate error correction encoded data D 202 .
- the magnetic recording and/or reproducing apparatus 200 modulation encodes the error correction encoded data D 202 from the error correction encoder 201 , by the modulation encoder 202 , to generate modulation-encoded data D 203 , which is a string of bits subjected to limitations.
- the magnetic recording and/or reproducing apparatus 200 performs filtering on the modulation-encoded data D 203 , supplied from the modulation encoder 202 , by the precoder 203 , in such a manner as to compensate for the channel characteristics as from the writing of data on the recording medium 250 up to outputting thereof at an equalizer 207 in the reproducing system, to generate a precode signal D 204 .
- the precoder 203 performs the filtering F indicated by the following equation (2):
- the magnetic recording and/or reproducing apparatus 200 then converts respective bits of the precode signal D 204 , as binary signal supplied from the precoder 203 , by a write current driver 204 , into write current values Is, such as by 0 ⁇ I s , 1 ⁇ +I s , to generate a write current signal D 205 .
- the magnetic recording and/or reproducing apparatus 200 applies a magnetic write signal D 206 , corresponding to the write current signal D 205 supplied from the write current driver 204 , to the recording medium 250 .
- the magnetic recording and/or reproducing apparatus 200 is able to record data on the recording medium 250 .
- the magnetic recording and/or reproducing apparatus 200 performs the following processing:
- the magnetic recording and/or reproducing apparatus 200 reads out the readout magnetization signal D 207 from the recording medium 250 by the readout head 206 to generate a readout current signal D 208 conforming to this readout magnetization signal D 207 .
- the magnetic recording and/or reproducing apparatus 200 then equalizes the readout current signal D 208 , supplied from the readout head 206 , by the equalizer 207 , so that the channel response since data writing on the recording medium 250 in the recording system until outputting thereof at the equalizer 207 will be of pre-set characteristics, such as 1-D, to generate an equalized signal D 209 .
- the magnetic recording and/or reproducing apparatus 200 then adjusts the gain of the equalized signal D 209 , supplied from the equalizer 207 , by the gain adjustment circuit 208 , based on a gain adjustment control signal D 213 from the gain adjustment control circuit 211 , to generate a gain adjustment signal D 210 .
- the gain adjustment control signal D 213 is generated by the gain adjustment control circuit 211 , based on the digital channel signal D 211 , as later explained.
- the gain adjustment control signal D 213 is a control signal for maintaining the amplitude of the equalization signal D 209 at an expected value.
- the magnetic recording and/or reproducing apparatus 200 digitizes the gain adjustment signal D 210 , supplied from the gain adjustment circuit 208 , to generate the digital channel signal D 211 . Meanwhile, the A/D converter 209 performs sampling based on the clock signal D 212 generated and supplied by the timing generating circuit 210 . The timing generating circuit 210 , fed with the digital channel signal D 211 , generates clocks to produce clock signals D 212 which are output to the A/D converter 209 .
- the magnetic recording and/or reproducing apparatus 200 feeds the digital channel signal D 211 , supplied from the A/D converter 209 , to the viterbi decoder 212 , which then performs viterbi decoding on the channel response from the upstream side of the precoder 203 in the recording system up to the outputting at the equalizer 207 in the reproducing system, for example, the channel response R ch represented by the following equation (3):
- the magnetic recording and/or reproducing apparatus 200 then applies modulation decoding on the viterbi decoded signal D 214 , supplied from the modulation decoder 213 , to realize data correspondence reversed from that in the modulation encoder 202 in the recording system to generate a modulated decoded signal D 215 which is an original input data string not subjected to limitations.
- the magnetic recording and/or reproducing apparatus 200 decodes the error correction codes of the modulated decoded signal D 215 , supplied from the modulation decoder 213 , by the error correction decoder 214 , to generate output data D 216 .
- the magnetic recording and/or reproducing apparatus 200 is able to reproduce the data recorded on the recording medium 250 .
- the modulation decoder 213 has no more than the function of realizing the correspondence between binary signals reversed from that obtained on modulation encoding by the modulation encoder 202 , while the signals in both the input and the output of the modulation decoder 213 needs to be binary signals, with the result that the signals on the downstream side of the viterbi decoder 212 are all binary signals.
- the present invention provides a data recording apparatus for recording data on a recording medium, including modulation encoding means for applying predetermined modulation encoding to input data, and interleaving means for interleaving data supplied from the modulation encoding means for re-arraying the data sequence.
- data supplied from the modulation encoding means is interleaved by the interleaving means for re-arraying the data sequence, thereby realizing high performance encoding.
- the present invention provides a data recording method for recording data on a recording medium, including a modulation encoding step of applying predetermined modulation encoding to input data, and a interleaving step of interleaving data supplied from the modulation encoding step for re-arraying the data sequence.
- data supplied from the modulation encoding step is interleaved in the interleaving step for re-arraying the data sequence for realizing high performance encoding.
- the present invention provides a data reproducing apparatus for reproducing data recorded by a recording equipment for recording data on a recording medium, including modulation encoding means for applying predetermined modulation encoding to input data and first interleaving means for interleaving data supplied from the modulation encoding means for re-arraying the data sequence, in which the data reproduction apparatus includes deinterleaving means for interleaving the input data in its sequence such as to restore the sequence of data bits re-arrayed by the first interleaving means to the bit sequence of the data as encoded by the modulation encoding means, modulation decoding means for modulation decoding the data supplied from the deinterleaving means, and second interleaving means for interleaving data corresponding to a difference between data output by the modulation decoding means and data output by the deinterleaving means based on the same interleaving position information as that of the first interleaving means for re-arraying the sequence of the difference data.
- the data reproduction apparatus includes deinterleaving means
- the data re-arrayed in its sequence interleaved by the deinterleaving means is modulation decoded by the modulation decoding means, whilst data corresponding to the difference between data output by the modulation decoding means and data output by the deinterleaving means is interleaved by the second interleaving means for re-arraying the sequence of the different data, whereby efficient decoding can be realized by exploiting the soft information for the entire decoding processing to lower the decoding error rate appreciably.
- the present invention provides a data reproducing method for reproducing data recorded by a recording method for recording data on a recording medium, including a modulation encoding step for applying predetermined modulation encoding to input data and a first interleaving step of interleaving data encoded in the modulation encoding step for re-arraying the data sequence, in which the data reproduction method includes a deinterleaving step of interleaving the input data in its sequence such as to restore the sequence of data bits re-arrayed by the first interleaving step to the bit sequence of the data as encoded by the modulation encoding step, a modulation decoding step of modulation decoding the data supplied from the deinterleaving step and a second interleaving step of interleaving data corresponding to a difference between data decoded in the modulation decoding step and data re-arrayed in the deinterleaving step based on the same interleaving position information as that of the first interleaving step for
- the data re-arrayed in its sequence interleaved by the deinterleaving means is modulation decoded in the modulation decoding step, whilst data corresponding to the difference between data output by the modulation decoding step and data output by the deinterleaving step is interleaved by the second interleaving step for re-arraying the sequence of the different data, whereby efficient decoding can be realized by exploiting the soft information for the entire decoding processing to lower the decoding error rate appreciably.
- the present invention provides a data recording and reproducing apparatus for recording and reproducing data for a recording medium
- the apparatus includes, as a recording system for recording data on the recording medium, modulation encoding means for applying predetermined modulation encoding to input data, and first interleaving means for interleaving data supplied from the modulation encoding means for re-arraying the data sequence
- the apparatus also includes, as a reproducing system for reproducing data recorded on the recording medium, deinterleaving means for interleaving the input data in its sequence such as to restore the sequence of data bits re-arrayed by the first interleaving means to the bit sequence of the data as encoded by the modulation encoding means, modulation decoding means for modulation decoding the data supplied from the deinterleaving means, and second interleaving means for interleaving data corresponding to a difference between data output by the modulation decoding means and data output by the deinterleaving means based on the same interlea
- the data supplied from the modulation encoding means is interleaved by first interleaving means to re-array the data sequence, whereas, if data recorded on the recording medium is to be reproduced, data given as a difference between second interleaving means for interleaving data corresponding to a difference between data output by the modulation decoding means and data output by the deinterleaving means based on the same interleaving position information as that of said first interleaving means is interleaved and re-arrayed, so that high performance encoding may be achieved, at the same time as efficient decoding may be achieved by exploiting the soft information for the entire decoding for the code, thus significantly lowering the decoding error rate.
- the present invention provides a data recording and reproducing method for recording and reproducing data for a recording medium, in which the method includes, as a recording system for recording data on the recording medium, a modulation encoding step for applying predetermined modulation encoding to input data, and a first interleaving step for interleaving data supplied from the modulation encoding step for re-arraying the data sequence, and in which the method also includes, as a reproducing system for reproducing data recorded on the recording medium, a deinterleaving step for interleaving the input data in its sequence such as to restore the sequence of data bits re-arrayed by the first interleaving step to the bit sequence of the data as encoded by the modulation encoding step, a modulation decoding step for modulation decoding the data supplied from the deinterleaving step, and a second interleaving step for interleaving data corresponding to a difference between data decoded in the modulation decoding step and data re-arrayed
- the data supplied from the modulation encoding step is interleaved by the first interleaving step to re-array the data sequence, whereas, if data recorded on the recording medium is to be reproduced, data given as a difference between second interleaving means for interleaving data corresponding to a difference between data output by the modulation decoding means and data output by the deinterleaving means based on the same interleaving position information as that of said first interleaving means is interleaved and re-arrayed, so that high performance encoding may be achieved, at the same time as efficient decoding may be achieved by exploiting the soft information for the entire decoding for the code, thus significantly lowering the decoding error rate.
- FIG. 1 illustrates an input/output example of a conventional modulation encoder.
- FIG. 2 is a block diagram showing the structure of a conventional modulation decoder.
- FIG. 3 is a block diagram showing the structure of another conventional modulation decoder.
- FIG. 4 is a block diagram showing the structure of a conventional magnetic recording and/or reproducing apparatus.
- FIG. 5 illustrates an input/output example in an interleaver applied to a recording system of a magnetic recording and/or reproducing apparatus shown as a first embodiment of the present invention.
- FIG. 6 illustrates the operation of an interleaver used in a recording system of the magnetic recording and/or reproducing apparatus shown in FIG. 5.
- FIG. 7 illustrates an input/output example in a decoder applied to a reproducing system of the magnetic recording and/or reproducing apparatus shown in FIG. 5.
- FIG. 8 is a block diagram for illustrating the structure of a decoder used in the reproducing system of the magnetic recording and/or reproducing apparatus shown in FIG. 5.
- FIG. 9 is a block diagram for illustrating the structure of the recording and/or reproducing apparatus shown in FIG. 5.
- FIG. 10 is a block diagram for illustrating the structure of a channel and a modulation turbo decoder provided in the reproducing system of the recording and/or reproducing apparatus shown in FIG. 5.
- FIG. 12 illustrates the trellis when status transition has occurred thrice in accordance with the status transition diagram shown in FIG. 11.
- FIG. 13 illustrates the trellis constructed on branch selection from the trellis shown in FIG. 12.
- FIG. 14 is a block diagram showing the structure of an encoder used in a recording system of a magnetic recording and/or reproducing apparatus shown as a second embodiment of the present invention.
- FIG. 15 is a block diagram for illustrating the structure of the magnetic recording and/or reproducing apparatus.
- FIG. 16 is a block diagram for illustrating the structure of the channel and a modulation turbo decoder provided in a reproducing system of the magnetic recording and/or reproducing apparatus.
- the present embodiment is directed to a magnetic recording and/or reproducing apparatus made up of a recording system for recording data on a recording medium of the magnetic recording system, such as a hard disc or a so-called DVCR (digital video cassette recorder), and a reproducing system for reproducing data recorded on these recording mediums.
- a recording system for recording data on a recording medium of the magnetic recording system such as a hard disc or a so-called DVCR (digital video cassette recorder)
- DVCR digital video cassette recorder
- This magnetic recording and/or reproducing apparatus includes, in its recording system, an interleaver downstream of a modulation encoder, adapted for modulating signals, and executes encoding by so-called serial concatenated coding between a modulation encoder and a precoder, adapted for performing filtering on signals, in such a manner as to compensate for channel characteristics. Moreover, the magnetic recording and/or reproducing apparatus uses, on the reproducing side, a decoder for the channel and a decoder for modulation decoding the modulation encoded signals, that is an SISO (soft input soft output) type decoder, fed with soft input data to output soft output data, and iteratively executes decoding between these two decoders.
- SISO soft input soft output
- turbo decoding This decoding is termed turbo decoding. That is, the magnetic recording and/or reproducing apparatus applies the encoding by the serial concatenated code and turbo decoding, known as the encoding method and decoding method giving the performance close to the Shannon limit as set by what is called the Shannon's theorem on the channel coding, to a recording and/or reproducing system performing data recording and/or reproduction for a recording medium.
- An interleaver 10 interleaves data, encoded by block modulation by a modulation encoder provided on a pre-stage of the interleaver 10 , on the modulation code block basis, that is on the symbol basis, to re-array the bits making up the data. For example, if the interleaver 10 re-arrays respective bits of data modulation-encoded to generate 3 output bits for 2 input bits in accordance with a conversion table shown in the following Table 3, the interleaver 10 re-arrays an input signal, fed in a unit of three bits, as a modulation encoder block unit, in a unit of three bits, as shown in FIG. 6, to generate an output signal: TABLE 3 Example of Conversion Table input bits output bits 00 011 01 101 10 111 11 110
- the interleaver 10 holds the interleaving position information of data determined on the basis of generated random numbers in e.g., a ROM (read-only memory), and re-arrays the input signal on the modulation code block basis, based on the interleaving position information.
- the interleaver 10 holds the interleaving position information of data making up an input signal, and re-arrays the bits on the modulation encoding block basis, in accordance with the interleaving position information, at a timing of generation of the bit string made up of N bits, where N is an optional natural number, to output the re-arrayed bits as an output signal at a preset timing.
- the decoder for modulation-decoding the modulation encoded signals is explained with reference to FIGS. 7 and 8. It should be noted that, although the decoders 20 , 30 , shown in FIGS. 7 and 8, are shown as being the decoders for modulation-decoding the modulation-encoded signals, the decoder for the channel is to be realized in a similar manner.
- R) that the respective bits of this reception signal R are each “0” and the probability P (R i 1
- R) that the respective bits of this reception signal R are each “1”. Ultimately, the decoder 20 calculates a posterior probability information P (M i 0
- R) and P (M i 1
- R), as a soft decision value for a modulation code block M represented by M (M 0 , M 1 , . . .
- a posterior probability information P (C i 0
- R) and P (C i 1
- R), as a soft decision value for a modulation code input block C represented by C (C 0 , C 1 , . . . , C k ⁇ 1 ), to output the so-calculated information.
- R)/P(M i 0
- R)) or log(P(C i 1
- R)/P(C i 0
- log values are routinely termed the log likelihood ratio and here denote the likelihood of the modulating code block M and the modulating code input block C on the occasion of inputting the reception signal R.
- the decoder may, for example, be configured as shown in FIG. 8.
- the decoder may, for example, be configured as shown in FIG. 8.
- data to be decoded has been encoded in accordance with the conversion table shown in Table 3 given above.
- the modulation decoder 30 includes six likelihood calculating circuits 31 1 , 31 2 , 31 3 , 31 4 , 31 5 and 31 6 , as means for calculating the likelihood of each reception bit, four adders 32 1 , 32 2 , 32 3 and 32 4 for summing the data, four log-sum circuits 33 1 , 33 2 , 33 3 and 33 4 for performing the operations of log (e A +e B ) on the two data A and B, four adders 34 1 , 34 2 , 34 3 and 34 4 for summing two data, five comparators 35 1 , 35 2 , 36 1 , 36 2 and 36 3 for taking the ratio of the two data, coefficient calculating circuits 37 1 , 37 2 and 37 3 for calculating coefficients for respective elements in the modulation encoding block M and three adders 38 1 , 38 2 and 38 3 for adding two data. It is noted that the number six of the likelihood calculating circuits is derived from three bits multiplied by 2 equals to six bits
- the likelihood calculating circuits 31 1 , 31 2 , 31 3 , 31 4 , 31 5 and 31 6 are respectively fed with respective reception bits in a reception signal D 31 (R) to calculate the likelihood of the respective reception bits.
- the likelihood calculating circuits 31 1 sends the generated log probability value D 32 1 to the adder 32 1 .
- the likelihood calculating circuits 31 2 sends the generated log probability value D 32 2 to the adders 32 2 , 32 3 and 32 4 and to the comparator 36 1 .
- the likelihood calculating circuits 31 3 sends the generated log probability value D 32 3 to the adder 32 2 and to the comparator 36 2 .
- the likelihood calculating circuits 31 4 sends the generated log probability value D 32 4 to the adder 32 1 , 32 3 and 32 4 and to the comparator 36 2 .
- the likelihood calculating circuits 31 5 sends the generated log probability value D 32 5 to the adder 32 4 and to the comparator 36 3 .
- the likelihood calculating circuits 31 6 sends the generated log probability value D 32 6 to the adders 32 1 , 32 2 and 32 3 and to the comparator 36 3 .
- the adder D 32 1 sums the log probability value D 32 1 , supplied from the likelihood calculating circuits 31 1 , the log probability value D 32 4 , supplied from the likelihood calculating circuits 31 4 and the log probability value D 32 6 , supplied from the likelihood calculating circuits 31 6 , to generate the likelihood value D 33 1 . That is, this likelihood value D 33 1 is not other than the probability represented by log P(R
- M 0 M 1 M 2 011).
- the adder D 32 1 sends the generated likelihood value D 33 1 to the log-sum circuits 33 1 , 33 3 .
- the adder D 32 2 sums the log probability value D 32 2 , supplied from the likelihood calculating circuits 31 2 , the log probability value D 32 3 , supplied from the likelihood calculating circuits 31 3 and the log probability value D 32 6 , supplied from the likelihood calculating circuits 31 6 to generate the likelihood value D 33 2 . That is, this likelihood value D 33 2 is not other than the probability represented by log P(R
- M 0 M 1 M 2 101).
- the adder D 32 2 sends the generated likelihood value D 33 2 to the log-sum circuits 33 1 , 33 4 .
- the adder D 32 3 sums the log probability value D 32 2 , supplied from the likelihood calculating circuits 31 2 , the log probability value D 32 4 , supplied from the likelihood calculating circuits 31 4 , and the log probability value D 32 6 , supplied from the likelihood calculating circuits 31 6 , to generate the likelihood value D 33 3 . That is, this likelihood value D 33 3 is not other than the probability represented by log P(R
- M 0 M 1 M 2 111).
- the adder D 32 3 sends the generated likelihood value D 33 3 to the log-sum circuits 33 2 , 33 3 .
- the adder D 32 4 sums the log probability value D 32 2 , supplied from the likelihood calculating circuits 31 2 , the log probability value D 32 4 , supplied from the likelihood calculating circuits 31 4 and the log probability value D 32 5 , supplied from the likelihood calculating circuits 31 5 , to generate the likelihood value D 33 4 . That is, this likelihood value D 33 4 is not other than the probability represented by log P(R
- M 0 M 1 M 2 110).
- the adder D 32 4 sends the generated likelihood value D 33 4 to the log-swn circuits 33 2 , 33 4 .
- the log-sum circuit 33 1 performs an operation shown by the equation (4):
- the log-sum circuit 33 1 sends the so-generated likelihood value D 34 1 to the adder 34 1 .
- the log-sum circuit 33 2 performs an operation shown by the equation (5):
- the log-sum circuit 33 3 performs an operation shown by the equation (6):
- the log-sum circuit 33 3 sends the so-generated likelihood value D 34 3 to the adder 34 3 .
- the log-sum circuit 33 4 sends the so-generated likelihood value D 34 4 to the adder 34 4 .
- This log probability value D 36 1 denotes the probability shown by the following equation (8):
- log P ( C 0 0
- R ) log ⁇ P ( R
- M 0 M 1 M 2 011)+( R
- the adder 34 1 sends the generated log probability value D 36 1 to a comparator 35 1 .
- This log probability value D 36 2 denotes the probability shown by the following equation (9):
- log P ( C 0 1
- R ) log ⁇ P ( R
- M 0 M 1 M 2 111)+( R
- the adder 34 2 sends the generated log probability value D 36 2 to a comparator 35 1 .
- This log probability value D 36 3 denotes the probability shown by the following equation (10):
- log P ( C 1 0
- R ) log ⁇ P ( R
- M 0 M 1 M 2 011)+( R
- the adder 34 3 sends the generated log probability value D 36 3 to the comparator 35 2 .
- This log probability value D 36 4 denotes the probability shown by the following equation (11):
- log P ( C 1 1
- R ) log ⁇ P ( R
- M 0 M 1 M 2 101)+( R
- the adder 34 4 sends the generated log probability value D 36 4 to a comparator 35 2 .
- R)/P(C 0 0
- R)/P(C 1 0
- R)/P(M 0 0
- R)/P(M 1 0
- R)/P(M 2 0
- the coefficient calculating circuit 37 1 sends the generated M 0 coefficient D 39 1 to the adder 38 1 .
- the coefficient calculating circuit 37 3 sends the generated M 2 coefficient D 39 3 to the adder 38 3 .
- the adder 38 1 sums the log posterior probability ratio D 38 1 , supplied from the comparator 36 1 , to the M 0 coefficient signal D 39 1 supplied from the coefficient calculating circuit D 37 1 .
- R)/P(M 0 0
- the adder 38 2 sums the log posterior probability ratio D 38 2 , supplied from the comparator 36 2 , to the M 1 coefficient signal D 39 2 supplied from the coefficient calculating circuit D 37 2 .
- R)/P(M 1 0
- the adder 38 3 sums the log posterior probability ratio D 38 3 , supplied from the comparator 36 3 , to the M 2 coefficient signal D 39 3 supplied from the coefficient calculating circuit D 37 3 .
- R)/P(M 2 0
- the decoder 30 having the components as described above, has the likelihood calculating circuits 31 1 , 31 2 , 31 3 , 31 4 , 31 5 and 31 6 for calculating the likelihood of respective reception bits in the reception signals D 31 (R) taking analog values under the effect of the noise generated in the course of transmission, as soft input, that is the respective output codewords on the modulation coder side.
- the modulation decoder 30 finds the likelihood of the respective codewords and uses the likelihood values, thus found, to find the posterior probability information straightforwardly, as soft decision values for the input and output bits on the modulation coder side.
- the decoder 30 is fed from outside with log priori probability D 35 1 , D 35 2 , D 35 3 , D 35 4 . If the probability of the respective bits making up the binary signal input to the modulation coder, not shown, being “0”, is equivalent to the same probability being “1”, there is no necessity of inputting the log priori probability D 35 1 , D 35 2 , D 35 3 , D 35 4 , it being only necessary to handle as if the values of these log priori probability D 35 1 , D 35 2 , D 35 3 , D 35 4 are all equal to zero.
- the modulation decoder 30 decodes data obtained on modulation-coding a 2-bit input to a 3-bit output
- the modulation decoder is not limited as to the number of bits of the input or the output and may be similarly configured in keeping with the number of bits of the input or the output used.
- a magnetic recording and/or reproducing apparatus 50 shown in FIG. 9, includes, as a recording system for recording data on a recording medium 70 , an error correction coder 51 for error correction coding input data, a modulation coder 52 for modulation coding input data, an interleaver 53 for re-arraying the input data, a precoder 54 for filtering the input data for compensating for channel characteristics, a write current driver 55 for converting respective bits of the input data into write current values, and a write head 56 for recording data on a recording medium 70 .
- the error correction coder 51 applies error correction coding to the input data D 51 .
- the error correction coder 51 sends the error correction encoded data D 52 , generated on error correction coding, to the downstream side modulation encoder 52 .
- the modulation encoder 52 applies predetermined modulation coding to the error correction encoded data D 52 , supplied from the error correction coder 51 , to generate modulation encoded data D 53 as a string subjected to limitations.
- the modulation encoder 52 sends the so-generated modulation encoded data D 53 to the downstream side interleaver 53 .
- the interleaver 53 is constructed as the aforementioned interleaver 10 , interleaving the modulation encoded data D 53 , encoded with block modulation by the modulation encoder 52 , on the modulation encoding block basis, to re-array the sequence of bits making up the modulation encoded data D 53 .
- the interleaver 53 sends the generated interleaved data D 54 to the downstream side precoder 54 .
- the precoder 54 as precoding means filters the interleaved data D 54 , supplied from the interleaver 53 , in such a manner as to compensate for channel characteristics from the data writing to the recording medium 70 to the outputting thereof in the equalizer 58 in the reproducing system, thereby generating a precode signal D 55 as a binary signal. For example, if the channel has 1-D characteristics the precoder 54 performs filtering F represented by the following equation (15):
- ⁇ denotes exclusive-OR.
- the precoder 54 sends the generated precode signal D 55 to the downstream side write current driver 55 .
- the write current driver 55 converts respective bits of the precode signal D 55 , supplied from the precoder 54 , into the write current value I s , so that 0 and 1 will be converted to ⁇ I s and +I s (0 ⁇ I s , 1 ⁇ +I s ), respectively, to generate a write current signal D 56 .
- the write current driver 55 sends the so-generated write current signal D 56 to the downstream side write head 56 .
- the write head 56 routes a write magnetic signal D 57 , conforming to the write current signal D 56 , supplied from the write current driver 55 , to the recording medium 70 to record data thereon.
- the recording system in this magnetic recording and/or reproducing apparatus 50 applies error correction coding to the input data D 51 , by the error correction coder 51 , to produce error correction coded data D 52 , which then is modulation-encoded in a predetermined fashion by the modulation-coder 52 .
- the so-produced modulation encoded data D 53 is interleaved by the interleaver 53 on the modulation encoding block basis to produce precode signal D 55 by the precoder 54 .
- the recording system records the precode signal D 55 , generated by the precoder 54 , on the recording mediwn 70 , through the write head 55 and the write head 56 .
- the recording system in the magnetic recording and/or reproducing apparatus includes the interleaver 53 downstream of the modulation encoder 52 , and executes serial concatenated coding between the modulation encoder 52 and the precoder 54 to realize high performance encoding as encoding downstream of the error correction coding and encoding for the channel.
- the magnetic recording and/or reproducing apparatus 50 includes, as a reproducing system for reproducing the data recorded on the recording medium 70 , a readout head 57 for reading out data recorded on the recording medium 70 , an equalizer 58 for equalizing input data, a gain adjustment circuit 59 for adjusting the gain of the input data, an analog/digital (A/D) converter 60 for converting analog data into digital data, a timing reproducing circuit 61 for reproducing clocks, a gain adjustment control circuit 62 for controlling the gain adjustment circuit 59 , a channel and modulation turbo decoder 63 for applying turbo soft decoding to the input data, and an error correcting soft decoder 64 for applying error correcting soft decoding to the input data.
- a reproducing system for reproducing the data recorded on the recording medium 70
- a readout head 57 for reading out data recorded on the recording medium 70
- an equalizer 58 for equalizing input data
- a gain adjustment circuit 59 for adjusting the gain of the input data
- the readout head 57 reads out a readout magnetization signal D 58 from the recording medium and generates a readout current signal D 59 corresponding to this readout magnetization signal D 58 .
- the readout head 57 sends the generated readout current signal D 59 to the downstream side equalizer 58 .
- the equalizer 58 equalizes the readout current signal D 59 , supplied from the readout head 57 , so that the channel response from data writing on the recording medium 70 in the recording system up to outputting thereof in the equalizer 58 will be of pre-set characteristics, such as 1-D, to generate an equalized signal D 60 .
- the equalizer 58 sends the generated equalized signal D 60 to the downstream side gain adjustment circuit 59 .
- the gain adjustment circuit 59 adjusts the gain of the equalized signal D 60 , supplied from the equalizer 58 , based on the gain adjustnent control signal D 64 supplied from the gain adjustment control circuit 62 , to generate a gain adjustment signal D 61 .
- the gain adjustment circuit 59 sends the generated gain adjustment signal D 61 to the downstream side A/D converter 60 .
- the A/D converter 60 samples the gain adjustment signal D 61 , supplied from the gain adjustment circuit 59 , based on the clock signal D 63 supplied from the timing generating circuit 61 , to digitize the gain adjustment signal D 61 to generate a digital channel signal D 62 .
- the A/D converter 60 sends the so-generated digital channel signal D 62 to the timing generating circuit 61 , gain adjustment control circuit 62 and to the channel and modulation turbo decoder 63 .
- the timing generating circuit 61 regenerates clocks from the digital channel signal D 62 , supplied from the A/D converter 60 , to generate clock signals D 63 .
- the timing generating circuit 61 routes the generated clock signals D 63 to the A/D converter 60 .
- the gain adjustment control circuit 62 Based on the digital channel signal D 62 , supplied from the A/D converter 60 , the gain adjustment control circuit 62 generates a gain adjustment control signal D 64 , which is a control signal used for maintaining the amplitude of the equalized signal D 60 at an expected value. The gain adjustment control circuit 62 sends the generated gain adjustment control signal D 64 to the gain adjustment circuit 59 .
- the channel and modulation turbo decoder 63 concatenates SISO decoders, constructed as the above-mentioned decoders 20 , 30 , to execute turbo decoding.
- the channel and modulation turbo decoder 63 is fed with the digital channel signal D 62 , supplied from the A/D converter 60 , to perform turbo decoding, and routes a so-generated turbo decoded signal D 65 to the post-stage error correcting soft decoder 64 .
- the error correcting soft decoder 64 applies the so-called BCJR (Bahl, Cocke, Jelinek and Rahiv) algorithm or the SOVA (soft output viterbi algorithm) to the turbo decoded signal D 65 , supplied from the channel and modulation turbo decoder 63 , to output the soft-decoded signal as soft or hard output data D 66 .
- the channel and modulation turbo decoder 63 includes a channel SISO decoder 81 , as an SISO type decoder for decoding the channel response from the pre-stage of the precoder 54 in the recording system up to the outputting stage of the equalizer 58 in the reproducing system, a deinterleaver 83 for restoring the sequence of the input data to the original sequence, a modulation SISO decoder 84 , as a decoder of the SISO type for modulation decoding the input data, a deinterleaver 86 for re-arraying the input data, a changeover switch 87 for switching the data input as the priori probability information to information bits and two difference taking units 82 , 85 .
- a channel SISO decoder 81 as an SISO type decoder for decoding the channel response from the pre-stage of the precoder 54 in the recording system up to the outputting stage of the equalizer 58 in the reproducing system
- a deinterleaver 83 for restoring the sequence of
- the channel SISO decoder 81 is constructed as the aforementioned decoders 20 , 30 , and is an SISO type decoder.
- the channel SISO decoder 81 is fed with the digital channel signal D 62 , as a soft input supplied from the A/D converter 60 , and with the priori probability information D 78 , which is the priori probability information D 76 for an information bit as a soft input supplied from the interleaver 86 , or the priori probability information D 77 for an information bit which is of a value “0”, as selected by the changeover switch 87 , and performs soft output decoding, based on the channel response R ch from the pre-stage of the precoder 54 in the recording system up to an output in the equalizer 58 , represented by the following equation (13):
- ⁇ denotes exclusive OR, in accordance with the aforementioned BCJR algorithm or SOVA.
- the channel SISO decoder 81 is not limited to the aforementioned decoders 20 , 30 , it being only sufficient if the channel SISO decoder 81 is constructed as an SISO decoder. For example, it is sufficient if the channel SISO decoder 81 performs soft output decoding, in accordance with the aforementioned BCJR algorithm or SOVA, based on the trellis corresponding to the channel response.
- the difference taking unit 82 takes the difference between the channel decoded signal D 71 , as a soft input, supplied from the channel SISO decoder 81 , and the priori probability information D 76 , as a soft input, supplied from the interleaver 86 , to output data represented by ths difference value as a soft output to the post-stage deinterleaver 83 , as the channel extrinsic information signals D 72 as the extrinsic information to an information bit as found by the code constraint condition. Meanwhile, this channel extrinsic information signals D 72 corresponds to the interleaved data D 54 as interleaved by the interleaver 53 of the recording system.
- the deinterleaver 83 deinterleaves the channel extrinsic information signals D 72 , as a soft input, supplied from the difference taking unit 82 , in order to restore the bit sequence of the interleaved data D 54 from the interleaver 53 of the recording system to the bit sequence of the original modulation encoded data D 53 .
- the deinterleaver 83 sends the deinterleaved data to the modulation SISO decoder 84 and to the difference taking unit 85 as the deinterleaved signal D 73 which is the priori probability information to the code bit in the modulation SISO decoder 84 .
- the difference taking unit 85 finds a difference value between the modulation channel decoded signal D 74 , as a soft input, supplied from the modulation SISO decoder 84 , and the deinterleaved signal D 73 as a soft input from the deinterleaver 83 , and outputs data given as this difference value to the post-stage interleaver 86 as a soft output as the modulated extrinsic information signals D 75 as the extrinsic information to the code bit as found by the constraint condition.
- the interleaver 86 interleaves the modulated extrinsic information signals D 75 , as a soft input fed from the difference taking unit 85 , based on the same interleaving position information as that of the interleaver 53 of the recording system.
- the interleaver 86 sends the interleaved data to the channel SISO decoder 81 and to the difference taking unit 82 as being the priori probability information signal D 76 for the information bit in the channel SISO decoder 81 .
- the changeover switch 87 is set to the fixed terminal a supplying a value 0 corresponding to the priori probability information signal D 77 to select the priori probability information signal D 77 as being the priori probability information signal D 78 for an information bit in the channel SISO decoder 81 .
- the changeover switch 87 then is set to a fixed terminal b supplying the priori probability information signal D 76 supplied from the interleaver 86 to select the priori probability information signal D 76 as being the priori probability information signal D 78 .
- the channel and modulation turbo decoder 63 is provided with the modulation SISO decoder 84 and the channel SISO decoder 81 , as counterparts to the modulation coder 52 and the precoder 54 of the recording system, respectively, as described above, to decompose the code of high decoding complexity into elements with lower decoding complexity, such as to sequentially improve characteristics by the interaction between the channel SISO decoder 81 and the modulation SISO decoder 84 .
- the channel and modulation turbo decoder 63 iterates the decoding operations from the channel SISO decoder 81 to the modulation SISO decoder 84 a pre-set number of times, such as several to tens of times, to route the soft-output log posterior probability ratio, obtained on decoding a pre-set number of times, as the turbo decoded signal D 65 to the post-stage error correcting soft decoder 64 .
- the reproducing system of the magnetic recording and/or reproducing apparatus 50 turbo-decodes the soft-input digital channel signal D 62 , generated through the readout head 57 , equalizer 58 , gain adjustment circuit 59 and the A/D converter 60 , by the channel and modulation turbo decoder 63 , to generate the turbo decoded signal D 65 corresponding to the error correction coded data D 52 input to the modulation coder 52 in the recording system.
- This reproducing system soft-decodes the turbo decoded signal D 65 , generated by the channel and modulation turbo decoder 63 , for error correction codes, by the error correcting soft decoder 64 , to output data as resulting soft output directly to outside as output data D 66 , or binary-codes the soft-output data to generate hard-output data D 66 , which is issued to outside.
- the reproducing system of the magnetic recording and/or reproducing apparatus 50 is provided in this manner with the channel and modulation turbo decoder 63 and performs turbo decoding between the modulation SISO decoder 84 and the channel SISO decoder 81 corresponding to the modulation coder 52 and the precoder 54 of the recording system to realize decoding in meeting with the channel response and the modulation encoding.
- turbo decoding with high efficiency can be realized by exploiting soft information for the entire decoding processing for the code, thus eliminating the necessity of diminishing the information. The result is the appreciably lowered decoding error rate.
- the second embodiment of the magnetic recording and/or reproducing apparatus executes encoding as correlation is afforded to fore and aft side data instead of coding/decoding on the block basis.
- the magnetic recording and/or reproducing apparatus performs trellis decoding conforming to the constraint condition.
- the interleaver is not limited to one interleaving the data based on the modulation encoding block of the trellis, such that any suitable interleaver interleaving the data such as to meet the pre-set constraint condition following interleaving may be used.
- the magnetic recording and/or reproducing apparatus performs modulation encoding and modulation decoding, based on a common trellis.
- labels affixed between the respective states indicate bits output in case of status transition. For example, if the status transition that has occurred is “S 0 ⁇ S 1 ⁇ S 2 ”, an output bit string is “00”.
- a branch lying at an uppermost position indicates that there is one path starting at the status S 2 and again getting to the status S 2 after three status transitions, with a corresponding output being “100”.
- FIG. 13 shows a trellis formed on branch selection as described above.
- each label affixed between different states indicate an input/output.
- a branch S 0 ⁇ S 2 indicates that, if “11” is input for the state S 0 , status transition occurs to the status S 2 , as “100” is output.
- the encoder applied to the magnetic recording and/or reproducing apparatus, shown as the second embodiment, repeats the status transition for encoding, in accordance with the trellis formed by the above-described sequence of operations, to generate a modulated code string having correlation between input data.
- the encoder may be provided with components shown for example in FIG. 14.
- the encoder 90 shown in FIG. 14, includes a state register 91 for holding the state of the encoder 90 , a next-state calculating circuit 92 , for calculating the next transition state, and an output signal calculating circuit 93 for calculating an output signal D 94 .
- the state register 91 is a 2-bit register holding 2 bits specifying the state of the current encoder 90 .
- the state register 91 sends a status signal D 92 , specifying the 2 bits indicating the current state, to the next-state calculating circuit 92 and to the output signal calculating circuit 93 , as the state register 91 holds 2 bits indicating the next state corresponding to the next state signal D 93 supplied from the next-state calculating circuit 92 .
- the next-state calculating circuit 92 calculates the next state in acccordance with the following input/output correlating table 4: TABLE 4 Typical Input/Output Correlating Table status signals input signals next-state signals 0 00 0 0 01 1 0 10 1 0 11 2 1 00 1 1 01 0 1 10 0 1 11 2 2 00 2 2 01 0 2 10 0 2 11 1 3 00 0 3 01 0 3 10 0 3 11 0
- next-state calculating circuit 92 sends the next state signal D 93 to the state register 91 .
- the output signal calculating circuit 93 calculates an output signal D 94 , in accordance with the following input/output correlating table 5: TABLE 5 Typical Input/Output Correlating Table status signals input signals output signals 0 00 111 0 01 110 0 10 010 0 11 100 1 00 110 1 01 011 1 10 111 1 11 100 2 00 100 2 01 101 2 10 111 2 11 110 3 00 111 3 01 111 3 10 111 3 11 111
- the encoder 90 When fed with the input signal D 91 , the encoder 90 calculates the next state, using this input signal D 91 and the status signal D 92 , by the next-state calculating circuit 92 , for storage sequentially in the state register 91 .
- the encoder 90 calculates an output signal D 94 , by the output signal calculating circuit 93 , using the input signal D 91 and the status signal D 92 , by the output signal calculating circuit 93 , to output the so-calculated output signal D 94 .
- a decoder for modulation decoding the signal, encoded by the above-described encoder applies the decoding, which is based on the BCJR or SOVA algorithm, in accordance with the trellis previously explained with reference to FIG. 13.
- the magnetic recording and/or reproducing apparatus is able to perform trellis decoding exploiting the signal correlation in the modulation encoder.
- the soft information can be output to the error correction decoding circuit provided downstream of the modulation decoder, thereby improving the decoding error rate.
- the magnetic recording and/or reproducing apparatus 100 includes, as a recording system for recording data on a recording medium 70 , an error correction encoder 101 for error correction encoding input data, a modulation encoder 101 , a modulation encoder 102 for modulation encoding input data, an interleaver 103 for re-arraying the input data in its sequence, a precoder 104 for filtering input data for compensating its channel characteristics, a write current driver 105 for converting respective bits of the input data into write current values, and a write head 106 for recording data on the recording medium 70 .
- the error correction encoder 101 As error correcting encoding means, error correction encodes the input data D 101 .
- the error correction encoder 101 sends the error correction encoded data D 102 to the downstream side modulation encoder 102 .
- the modulation encoder 102 is configured as the aforementioned modulation encoder 90 . Specifically, it is a modulation encoder for repeating status transitions in accordance with the trellis, by way of encoding, for generating a modulated code string exhibiting correlation between input data.
- the modulation encoder 102 applies pre-set trellis modulation coding to the error correction coded data D 102 , supplied from the error correction encoder 101 , to generate modulated encoded data D 103 as a string subjected to limitation.
- the modulation encoder 102 sends the generated modulation encoded data D 103 to the downstream side interleaver 103 .
- the interleaver 103 interleaves the modulated encoded data D 103 in terms of the trellis modulation encoding block as a unit, to re-array the sequence of bits making up the modulated encoded data D 103 .
- the interleaver 103 sends the generated interleaved data D 104 to the downstream side precoder 104 .
- the precoder 104 filters the interleaved data D 104 , supplied from the interleaver 103 , in such a manner as to compensate for channel characteristics from the data writing to the recording medium 70 to the output in the equalizer 108 in the reproducing system, thereby generating a precode signal D 105 as a binary signal.
- the precoder 104 sends the so-generated precede signal D 105 to the downstream side write current driver 105 .
- the write current driver 105 converts respective bits of the precode signal D 104 , supplied from the precoder 103 , into the write current value I s , to generate a write current signal D 106 .
- the write current driver 105 sends the generated write current signal D 106 to a downstream side write head 106 .
- the write head 106 applies a magnetic write signal D 107 , corresponding to the write current signal D 106 supplied from the write current driver 105 , to the recording medium 70 , to record data thereon.
- the recording system in the magnetic recording and/or reproducing apparatus 100 error correction encodes the input data D 101 by the error correction encoder 101 .
- the recording system then applies pre-set trellis modulation encoding to error correction encoded data D 102 by the modulation encoder 102 and interleaves the modulated encoded data D 103 by the interleaver 103 based on the pre-set trellis modulation encoding block to generate a precede signal D 105 by the precoder 104 .
- the recording system records the precode signal D 105 , generated by the precoder 104 , on the recording medium 70 , by the write current driver 105 and the write head 106 .
- the recording system of the magnetic recording and/or reproducing apparatus 100 thus having the interleaver 103 downstream of the modulation encoder 102 , effects encoding by serial concatenated coding between the modulation encoder 102 and the precoder 104 to realize high performance coding as modulation encoding and channel coding downstream of the error correction coding.
- the magnetic recording and/or reproducing apparatus 100 includes a readout head 107 for reading out data recorded on the recording medium 70 , an equalizer 108 for equalizing input data, a gain adjustment circuit 109 for adjusting the gain of the input data, an A/D circuit 110 for converting analog data to digital data, a timing circuit 111 for reproducing clocks, a gain adjustment control circuit 112 for controlling the gain adjustment circuit 109 , a modulation turbo decoder 113 for turbo-decoding the input data and an error correction soft decoder 104 for error correction soft decoding the input data.
- a readout head 107 reads out the readout magnetization signal D 108 from the recording medium 70 to generate a readout current signal D 109 conforming to the readout magnetization signal D 108 .
- the readout head 107 sends the so-generated current signal D 109 to the downstream side equalizer 108 .
- the equalizer 108 equalizes the readout current signal D 109 , supplied from the readout head 107 , so that the channel response from the data writing on the recording medium 70 in the recording system up to the outputting at the equalizer 108 will be of pre-set characteristics, to generate an equalized signal D 110 .
- the equalizer 108 routes the generated equalized signal D 110 to the downstream side gain adjustment circuit 109 .
- the gain adjustment circuit 109 adjusts the gain of the equalized signal D 110 supplied from the equalizer 108 , based on a gain adjustment control signal D 114 , supplied from the gain adjustment control circuit 112 , to generate a gain adjustment signal D 111 .
- the gain adjustment circuit 109 routes the generated gain adjustment signal D 111 to the downstream side A/D converter 110 .
- the A/D converter 110 samples and digitizes the gain adjustment signal D 111 , supplied from the gain adjustment circuit 109 , based on the clock signal D 113 , supplied from the timing regenerating circuit 111 , to generate a digital channel signal D 112 .
- the A/D converter 110 sends the generated digital channel signal D 112 to the timing regenerating circuit 111 , gain adjustment control circuit 112 and to the channel and modulation turbo decoder 113 .
- the timing regenerating circuit 111 regenerates clocks from the digital channel signal D 112 supplied from the A/D converter 110 to generate clock signals D 113 .
- the timing regenerating circuit 111 sends the generated clock signals D 113 to the A/D converter 110 .
- the gain adjustment control circuit 112 Similarly to the gain adjustment control circuit 62 of the magnetic recording and/or reproducing apparatus 50 , the gain adjustment control circuit 112 generates, based on the digital channel signal D 112 , supplied from the A/D converter 110 , a gain adjustment control signal D 114 , which is a control signal used for maintaining the amplitude of the equalized signal D 110 at an expected value. The gain adjustment control circuit 112 sends the generated gain adjustment control signal D 114 to the gain adjustment circuit 109 .
- the channel and modulation turbo decoder 113 is comprised of concatenated SISO decoders to effect turbo decoding.
- the channel and modulation turbo decoder 113 turbo-decodes the input digital channel signal D 112 from the A/D converter 110 to route the generated turbo decoded signal D 115 to the downstream side error correction decoder 114 .
- the error correction soft decoder 114 soft-decoded the turbo decoded signal D 115 supplied from the modulation SISO decoder 113 for errors based on the BCJR algorithm or SOVA to output soft or hard output data D 116 to outside.
- the channel and modulation turbo decoder 113 includes a channel SISO decoder 121 , as an SISO decoder for decoding the channel response from the pre-stage of the precoder 104 in the recording system to the outputting in the equalizer 108 , a deinterleaver 123 for restoring the sequence of the input data, an SISO decoder 124 , as a SISO decoder for modulation decoding the input data, an interleaver 126 for re-arraying the sequence of the input data, a changeover switch 127 for changing over input data input as the priori probability information for information bits and two difference taking units 122 , 125 .
- a channel SISO decoder 121 as an SISO decoder for decoding the channel response from the pre-stage of the precoder 104 in the recording system to the outputting in the equalizer 108
- a deinterleaver 123 for restoring the sequence of the input data
- an SISO decoder 124 as a SISO decode
- the channel SISO decoder 121 is fed with the digital channel signal D 112 , as a soft input supplied from the A/D converter 110 , and with priori probability information D 128 , as selected by the changeover switch 127 from the priori probability information D 126 for information bits supplied as soft input from the A/D converter 110 and the priori probability information D 127 for information bits having a value of “0”, to effect soft output decoding, based on the BCJR algorithm or SOVA, in accordance with the trellis for the channel response from the parentage of the precoder 104 in the recording system to an output in the equalizer 108 in the reproducing system.
- the difference taking unit 122 finds a difference between the channel decoded signal D 121 , as soft input, supplied from the channel SISO decoder 121 , and the priori probability information D 126 , as soft input, supplied from the interleaver 126 , to output data corresponding to this difference value as soft output to the downstream side deinterleaver 123 as the channel extrinsic information signals D 122 for an information bit as found by the code constraint condition. Meanwhile, the channel extrinsic information signals D 122 corresponds to the interleaved data D 104 obtained on interleaving by the interleaver 103 in the recording system.
- the deinterleaver 123 deinterleaves the bit sequence of the interleaved data D 104 from the interleaver 103 of the recording system to the channel extrinsic information signals D 122 supplied from the difference taking unit 122 in order to restore the bit sequence to that of the original modulated encoded data D 103 .
- the deinterleaver 123 sends the deinterleaved data to the modulation SISO decoder 124 and to the difference taking unit 122 as the deinterleaved signal D 123 which is the priori probability information for the code bits in the modulation SISO decoder 124 .
- the modulation SISO decoder 124 decodes signals encoded by the modulation encoder 102 in the recording system, and is an SISO type modulation decoder.
- the difference taking unit 125 finds a difference between the modulation channel decoded signal D 124 , supplied as soft input from the modulation SISO decoder 124 , and the deinterleaved signal D 123 , supplied as soft input from the deinterleaver 123 , to output the data as the difference value as soft output to the downstream side interleaver 126 as the modulated extrinsic information signals D 125 , which is the extrinsic information for a code bit as found by the code constraint condition.
- the interleaver 126 interleaves the modulated extrinsic information signals D 125 , supplied from the difference taking unit 125 , based on the same interleaving position information as that of the interleaver 103 of the recording system.
- the interleaver 126 sends the interleaved data to the channel SISO decoder 121 and to the difference taking unit 122 as being the priori probability information signal D 126 for the information bit in the channel SISO decoder 121 .
- the changeover switch 127 is set to the fixed terminal c supplying a value 0 corresponding to the priori probability information signal D 127 to select the priori probability information signal D 127 as being the priori probability information signal D 128 for an information bit in the channel SISO decoder 121 .
- the changeover switch 127 then is set to a fixed terminal d supplying the priori probability information signal D 126 supplied from the interleaver 126 to select the priori probability information signal D 126 as being the priori probability information signal D 128 .
- the channel and modulation turbo decoder 113 is provided with the modulation SISO decoder 124 and the channel SISO decoder 121 , as counterparts to the modulation coder 102 and the precoder 104 of the recording system, respectively, as described above, to decompose the code of high decoding complexity into elements with lower decoding complexity, such as to sequentially improve characteristics by the interaction between the channel SISO decoder 121 and the modulation SISO decoder 124 .
- the channel and modulation turbo decoder 113 If fed with the digital channel signal D 112 , as a soft input, from the A/D converter 110 , the channel and modulation turbo decoder 113 iterates the decoding operations from the channel SISO decoder 121 to the modulation SISO decoder 124 a pre-set number of times, such as several to tens of times, to route the soft-output log posterior probability ratio, obtained on decoding a pre-set number of times, as the turbo decoded signal D 115 to the post-stage error correcting soft decoder 64 .
- the reproducing system of the magnetic recording and/or reproducing apparatus 50 turbo-decodes the soft-input digital channel signal D 112 , generated through the readout head 107 , equalizer 108 , gain adjustment circuit 109 and the A/D converter 110 , by the channel and modulation turbo decoder 113 , to generate the turbo decoded signal D 115 corresponding to the error correction coded data D 102 input to the modulation coder 102 in the recording system.
- This reproducing system soft-decodes error correction codes of the turbo decoded signal D 115 , generated by the channel and modulation turbo decoder 113 , by the error correcting soft decoder 114 , to output data as resulting soft output directly to outside as output data D 116 , or binary-codes the soft-output data to generate hard-output data D 116 which is issued to outside.
- the reproducing system of the magnetic recording and/or reproducing apparatus 100 is provided in this manner with the channel and modulation turbo decoder 113 and performs turbo decoding between the modulation SISO decoder 124 and the channel SISO decoder 121 corresponding to the modulation coder 102 and the precoder 104 of the recording system to realize decoding in meeting with the channel response and the modulation encoding.
- the magnetic recording and/or reproducing apparatus 100 includes, in its recording system, the interleaver 103 downstream of t the modulation encoder 102 , to effect encoding by serial concatenated code between the modulation encoder 102 and the precoder 104 , while including, on its reproducing side, the channel and modulation turbo decoder 113 to effect turbo decoding to realize high performance coding as well as highly efficient turbo decoding exploiting the soft information for the entire decoding processing for the code. Since there is no necessity of diminishing the information, the decoding error rate can be lowered significantly. Moreover, the magnetic recording and/or reproducing apparatus 100 effects coding in the recording system, as correlation is afforded to the fore and aft side data. In addition, trellis decoding can be performed on the reproducing side in meeting with the constraint condition, thus further lowering the decoding error rate.
- the above-described magnetic recording and/or reproducing apparatus 50 , 100 are able to perform efficient turbo decoding by exploiting the soft information, thereby lowering the decoding error rate.
- encoding can be made as correlation is afforded to the fore and aft side data, without doing block-based encoding or decoding, while trellis decoding can be made in meeting with the constraint conditions, thus further lowering the decoding error rate. That is, the magnetic recording and/or reproducing apparatus 50 , 100 is able to realize high precision decoding, thus assuring high operational reliability fort the user.
- the present invention is not limited to the above-described embodiment.
- the present invention may be applied to a recording medium 70 other than the recording medium of the magnetic recording system, that is to a recording medium by the optical recording system, such as a so-called CD (Compact Disc) or to the DVD (Digital Versatile Disc) or to a recording medium of the photomagnetic recording system, such as a so-called magneto-optical disc (MO) disc.
- CD Compact Disc
- DVD Digital Versatile Disc
- MO magneto-optical disc
- the magnetic recording and/or reproducing apparatus 100 performs trellis modulation encoding on the encoder side and trellis modulation decoding on the decoder side.
- the present invention is applicable to such a case wherein the trellis modulation decoding is performed on the decoder side to output a soft decision value even in case the trellis modulation encoding is not performed on the encoding side, as when block modulation is effected on the encoder side.
- the magnetic recording and/or reproducing apparatus 50 or 100 is a unitary apparatus provided with the recording and reproducing systems.
- a unitary recording apparatus may be configured as a recording system for recording data on a recording medium, while a unitary reproducing apparatus may also be configured as a reproducing system for reproducing the data recorded on the recording apparatus.
Abstract
A method and apparatus for recording or reproducing data in which high performance encoding and a high efficiency decoding are realized to lower the decoding error rate. A magnetic recording and/or reproducing apparatus 50 includes, in a recording system, a modulation encoder 52 for modulation encoding input data in a predetermined fashion and an interleaver 53 for interleaving data supplied from the modulation encoder 52 to re-array the data sequence. The magnetic recording and/or reproducing apparatus 50 also includes, in a reproducing system, a first deinterleaver for interleaving the input data for re-arraying the data sequence so that the bit sequence of data re-arrayed by the interleaver 53 will be restored to its original bit sequence, a modulation SISO decoder for modulation decoding data supplied from the first deinterleaver and a second deinterleaver for interleaving data corresponding to a difference value between data output by the modulation SISO decoder and data output by the first deinterleaver to re-array the data sequence of the difference data.
Description
- 1. Field of the Invention
- This invention relates to a method and apparatus for recording data on a recording medium, a method and apparatus for reproducing data recorded on a recording medium and a method and apparatus for recording and/or reproducing data for a recording medium.
- 2. Description of Related Art
- As a recording medium for recording digital data, there are known a wide variety of recording mediums of the magnetic, optical or photomagnetic system, such as a hard disc, a so-called DVCR (digital video cassette recorder) or a so-called CD (Compact Disc), DVD (digital versatile disc) and a so-called MO (magneto-optical disc).
- For recording signals on these recording mediums, physical processing needs to be performed on the recording mediums, such as by controlling the direction of magnetization by a write head for a recording medium of the magnetic recording system, or by forming pits of lengths corresponding to signals by a stamper for a recording medium of the optical recording system. In this case, in order to permit amplitude control of readout signals or clock reproduction on the reproducing side reading out the signals recorded on the recording medium to operate as normally, the signal recording side for recording signals on a recording medium routinely uses a system of modulation encoding the signal in a pre-set manner to record the resulting modulation-coded signal.
- A modulation-coder, performing this modulation coding, routinely is fed with binary signals exempt from various limitations, and outputs binary signals free of various limitations. These limitations on the signals include DC free limitations which state that the numbers of “0”s and “1”s be equalized over a sufficient long length of the concatenations of “0”s and “1”s, and the (d, k) limitations which state that the minimum and maximum numbers of consecutive “0”s and “1”s in a code be d and k, respectively. FIG. 1 shows an input/output example in a modulation coder outputting a code satisfying the (d, k)=(2, 7) limitations. Specifically, a
modulation coder 150, outputting a code satisfying the (d, k)=(2, 7) limitation, is shown in FIG. 1, by way of concrete explanation of the concept of the (d, k) limitations. That is, if an input signal, free of the limitation, is input to themodulation coder 150, outputting a code satisfying the (d, k)=(2, 7) limitation, modulation-encodes the input signal to generate and output an output signal in which the minimum and maximum numbers of consecutive “0”s are 2 and 7, respectively. - The above example indicates that, in converting a bit string free of a limitation is converted into another bit string subjected to a limitation, the total number of the output bits is larger than that of the input bits. If the total number of input bits is K and the total number of output bits is N, the ratio K/N is represented as a code rate R. This code rate R serves as an index indicating the efficiency of the modulation coding. If two or more modulation coders, generating output signals satisfying the same limitations, are compared to one another, a modulation coder having the high code rate R is able to encode more input bits for a given number of output bits than one having the low code rate R. Stated differently, a modulation coder having a high code rate R is able to record more information on a pre-set recording medium than one having a low code rate R.
- The modulation coding may be classified into a block coding system in which input bits are divided into plural blocks of pre-set lengths and output bits generated are divided into plural blocks of pre-set lengths corresponding to the blocks of the input bits, and a variable length coding system, in which encoding units of input bits and output bits associated with the input bits are varied. For example, the so-called 8/9 code or the 16/17 code, routinely used for modulation coding, belong to the block coding system, whilst the so-called (1, 7) RLL code or the (2, 7) RLL code belong to the variable length encoding system.
- For example, in a block modulation encoding system, fed with two bits as input bits, and generating three output bits satisfying the (d, k)=(0, 2) limitations, a modulation coder has a conversion table as Table 1:
TABLE 1 Example of Conversion Table input bits output bits 00 011 01 101 10 111 11 110 - stored in e.g., a memory, not shown. The modulation coder references this conversion table and finds, for each 2-bit input bits, an associated 3-bit output bits, with the output bits being issued as output sequentially.
- On the other hand, a modulation decoder for modulating-decoding the modulation-coded signals has a back-conversion table, as Table 2:
TABLE 2 Example of Back-Conversion Table input bit decoded bits 000 01 001 00 010 10 011 00 100 11 101 01 110 11 111 10 - corresponding to the conversion table of Table 1, stored in e.g., a memory, not shown. The modulation decoder references this back-conversion table to find and sequentially output 2-bit decoded bits, associated with the 3-bit input bits.
- FIG. 2 shows a
typical modulation decoder 160 having at least a ROM (read-only memory) 161. Themodulation decoder 160 is fed with an input address signal D161 to output the contents stored in an address of theROM 161 corresponding to this input address signal D161 as a demodulated decoded signal D162. In actuality, if the input bits are back-converted into decoded bits in accordance with the back-conversion table shown in Table 2, the contents of the decoded bits are stored in addresses of aROM 161 of themodulation decoder 160, corresponding to the input bits in Table 2. The decoded bits, stored in these addresses, are read out by way of performing the back-conversion. - FIG. 3 shows a
typical modulation decoder 170 at least having acombination circuit 171. Themodulation decoder 170 is fed with an input signal D171 and executes logical operations on the input signal D171 by thecombination circuit 171 to generate a modulated decoded signal D172. In actuality, if, in performing back conversion from the input bits to the decoded bits in accordance with the back-conversion table of Table 2, the three-bit input signal D171 is represented as (a0, a1, a2) and a two-bit modulated decoded signal D172 is represented as (b0, b1), themodulation decoder 170 generates the output bits (b0, b1) by thecombination circuit 171 corresponding to the following logical equations (1): - b 0=(a 1&a 2)|(a 0&!a 1&!a 2)|(!a 0&a 1&!a 2)
- b 1=(a 0&!a 1)|(!a 0&!a 1&!a 2)|(a 0&a 1&!a 2) (1)
- where |, & and ! indicate the logical sum, logical product and logical negation, respectively.
- If the modulation coder and the modulation decoder are applied to a magnetic recording and/or reproducing apparatus for recording and/or reproducing data on or from a recording medium in accordance with the magnetic recording system, the recording and/or reproducing apparatus is configured as shown in FIG. 4.
- That is, the magnetic recording and/or reproducing
apparatus 200, shown in FIG. 4, includes, as a recording system for recording data on arecording medium 250, anerror correction encoder 201 for error correction encoding input data, amodulation encoder 201, amodulation encoder 202 for modulation encoding the input data, aprecoder 203 for filtering input data for compensating its channel characteristics, a writecurrent driver 204 for converting respective bits of the input data into write current values, and awrite head 205 for recording data on therecording medium 250. The magnetic recording and/or reproducingapparatus 200 also includes, as a playback system for reproducing data recorded on therecording medium 250, areadout head 206 for reading out data recording on therecording medium 250, anequalizer 207 for equalizing the input data, again adjustment circuit 208 for adjusting the gain of the input data, an analog/digital converter (A/D converter) 209 for converting analog data into digital data, atiming generating circuit 210 for generating clocks, a gainadjustment control circuit 211 for controlling thegain adjustment circuit 208, aviterbi decoder 212 for viterbi-decoding the input bits, amodulation decoder 213 for modulation decoding the input data and anerror correction decoder 214 for error correction decoding the input data. - In recording data on the
recording medium 250, the magnetic recording and/or reproducingapparatus 200 performs the following operations: - When fed with the input data D201, the magnetic recording and/or reproducing
apparatus 200 applies error correction coding to the input data D201, by theerror correction encoder 201, to generate error correction encoded data D202. - The magnetic recording and/or reproducing
apparatus 200 modulation encodes the error correction encoded data D202 from theerror correction encoder 201, by themodulation encoder 202, to generate modulation-encoded data D203, which is a string of bits subjected to limitations. - The magnetic recording and/or reproducing
apparatus 200 performs filtering on the modulation-encoded data D203, supplied from themodulation encoder 202, by theprecoder 203, in such a manner as to compensate for the channel characteristics as from the writing of data on therecording medium 250 up to outputting thereof at anequalizer 207 in the reproducing system, to generate a precode signal D204. For example, if the channel has 1-D characteristics, theprecoder 203 performs the filtering F indicated by the following equation (2): - F=1/(1⊕D) (2)
- where ⊕ denotes exclusive-OR.
- The magnetic recording and/or reproducing
apparatus 200 then converts respective bits of the precode signal D204, as binary signal supplied from theprecoder 203, by a writecurrent driver 204, into write current values Is, such as by 0→−Is, 1→+Is, to generate a write current signal D205. - By the
write head 205, the magnetic recording and/or reproducingapparatus 200 applies a magnetic write signal D206, corresponding to the write current signal D205 supplied from the writecurrent driver 204, to therecording medium 250. - By the above processing, the magnetic recording and/or reproducing
apparatus 200 is able to record data on therecording medium 250. - In reproducing the data recorded on the
recording medium 250, the magnetic recording and/or reproducingapparatus 200 performs the following processing: - First, the magnetic recording and/or reproducing
apparatus 200 reads out the readout magnetization signal D207 from therecording medium 250 by thereadout head 206 to generate a readout current signal D208 conforming to this readout magnetization signal D207. - The magnetic recording and/or reproducing
apparatus 200 then equalizes the readout current signal D208, supplied from thereadout head 206, by theequalizer 207, so that the channel response since data writing on therecording medium 250 in the recording system until outputting thereof at theequalizer 207 will be of pre-set characteristics, such as 1-D, to generate an equalized signal D209. - The magnetic recording and/or reproducing
apparatus 200 then adjusts the gain of the equalized signal D209, supplied from theequalizer 207, by thegain adjustment circuit 208, based on a gain adjustment control signal D213 from the gainadjustment control circuit 211, to generate a gain adjustment signal D210. Meanwhile, the gain adjustment control signal D213 is generated by the gainadjustment control circuit 211, based on the digital channel signal D211, as later explained. Specifically, the gain adjustment control signal D213 is a control signal for maintaining the amplitude of the equalization signal D209 at an expected value. - By the A/
D converter 209, the magnetic recording and/or reproducingapparatus 200 digitizes the gain adjustment signal D210, supplied from thegain adjustment circuit 208, to generate the digital channel signal D211. Meanwhile, the A/D converter 209 performs sampling based on the clock signal D212 generated and supplied by thetiming generating circuit 210. The timing generatingcircuit 210, fed with the digital channel signal D211, generates clocks to produce clock signals D212 which are output to the A/D converter 209. - The magnetic recording and/or reproducing
apparatus 200 feeds the digital channel signal D211, supplied from the A/D converter 209, to theviterbi decoder 212, which then performs viterbi decoding on the channel response from the upstream side of theprecoder 203 in the recording system up to the outputting at theequalizer 207 in the reproducing system, for example, the channel response Rch represented by the following equation (3): - R ch=(1−D)/(1⊕D) (3)
- where ⊕ denotes Exclusive-OR.
- The magnetic recording and/or reproducing
apparatus 200 then applies modulation decoding on the viterbi decoded signal D214, supplied from themodulation decoder 213, to realize data correspondence reversed from that in themodulation encoder 202 in the recording system to generate a modulated decoded signal D215 which is an original input data string not subjected to limitations. - The magnetic recording and/or reproducing
apparatus 200 decodes the error correction codes of the modulated decoded signal D215, supplied from themodulation decoder 213, by theerror correction decoder 214, to generate output data D216. - By the above processing, the magnetic recording and/or reproducing
apparatus 200 is able to reproduce the data recorded on therecording medium 250. - Meanwhile, in the above-described conventional magnetic recording and/or reproducing
apparatus 200, themodulation decoder 213 has no more than the function of realizing the correspondence between binary signals reversed from that obtained on modulation encoding by themodulation encoder 202, while the signals in both the input and the output of themodulation decoder 213 needs to be binary signals, with the result that the signals on the downstream side of theviterbi decoder 212 are all binary signals. - In other words, it is necessary in the magnetic recording and/or reproducing
apparatus 200 to generate binary signals on the upstream side of themodulation decoder 213 and to process the binary signals even on the downstream side of themodulation decoder 213. - Thus, in the magnetic recording and/or reproducing
apparatus 200, in which bi-level binary signals need to be used, the information volume in the signal is diminished intentionally with the result that efficient decoding cannot be realized to deteriorate the decoding error rate. - It is therefore an object of the present invention to provide a method and apparatus for recording data in which high performance encoding may be carried out to cause the reproducing system to perform highly efficient decoding operation to lower the decoding error rate significantly.
- It is another object of the present invention to provide a data reproducing method and apparatus for performing efficient decoding to lower the decoding error rate.
- It is yet another object of the present invention to provide a data recording and reproducing method and apparatus for realizing high performance encoding and high efficiency decoding to lower the decoding error rate.
- In one aspect, the present invention provides a data recording apparatus for recording data on a recording medium, including modulation encoding means for applying predetermined modulation encoding to input data, and interleaving means for interleaving data supplied from the modulation encoding means for re-arraying the data sequence.
- In the data recording apparatus, according to the present invention, data supplied from the modulation encoding means is interleaved by the interleaving means for re-arraying the data sequence, thereby realizing high performance encoding.
- In another aspect, the present invention provides a data recording method for recording data on a recording medium, including a modulation encoding step of applying predetermined modulation encoding to input data, and a interleaving step of interleaving data supplied from the modulation encoding step for re-arraying the data sequence.
- In the data recording method, according to the present invention, data supplied from the modulation encoding step is interleaved in the interleaving step for re-arraying the data sequence for realizing high performance encoding.
- In another aspect, the present invention provides a data reproducing apparatus for reproducing data recorded by a recording equipment for recording data on a recording medium, including modulation encoding means for applying predetermined modulation encoding to input data and first interleaving means for interleaving data supplied from the modulation encoding means for re-arraying the data sequence, in which the data reproduction apparatus includes deinterleaving means for interleaving the input data in its sequence such as to restore the sequence of data bits re-arrayed by the first interleaving means to the bit sequence of the data as encoded by the modulation encoding means, modulation decoding means for modulation decoding the data supplied from the deinterleaving means, and second interleaving means for interleaving data corresponding to a difference between data output by the modulation decoding means and data output by the deinterleaving means based on the same interleaving position information as that of the first interleaving means for re-arraying the sequence of the difference data.
- In such data reproducing apparatus, according to the present invention, the data re-arrayed in its sequence interleaved by the deinterleaving means is modulation decoded by the modulation decoding means, whilst data corresponding to the difference between data output by the modulation decoding means and data output by the deinterleaving means is interleaved by the second interleaving means for re-arraying the sequence of the different data, whereby efficient decoding can be realized by exploiting the soft information for the entire decoding processing to lower the decoding error rate appreciably.
- In still another aspect, the present invention provides a data reproducing method for reproducing data recorded by a recording method for recording data on a recording medium, including a modulation encoding step for applying predetermined modulation encoding to input data and a first interleaving step of interleaving data encoded in the modulation encoding step for re-arraying the data sequence, in which the data reproduction method includes a deinterleaving step of interleaving the input data in its sequence such as to restore the sequence of data bits re-arrayed by the first interleaving step to the bit sequence of the data as encoded by the modulation encoding step, a modulation decoding step of modulation decoding the data supplied from the deinterleaving step and a second interleaving step of interleaving data corresponding to a difference between data decoded in the modulation decoding step and data re-arrayed in the deinterleaving step based on the same interleaving position information as that of the first interleaving step for re-arraying the sequence of the difference data.
- In such data reproducing method, according to the present invention, the data re-arrayed in its sequence interleaved by the deinterleaving means is modulation decoded in the modulation decoding step, whilst data corresponding to the difference between data output by the modulation decoding step and data output by the deinterleaving step is interleaved by the second interleaving step for re-arraying the sequence of the different data, whereby efficient decoding can be realized by exploiting the soft information for the entire decoding processing to lower the decoding error rate appreciably.
- In still another aspect, the present invention provides a data recording and reproducing apparatus for recording and reproducing data for a recording medium, in which the apparatus includes, as a recording system for recording data on the recording medium, modulation encoding means for applying predetermined modulation encoding to input data, and first interleaving means for interleaving data supplied from the modulation encoding means for re-arraying the data sequence, and in which the apparatus also includes, as a reproducing system for reproducing data recorded on the recording medium, deinterleaving means for interleaving the input data in its sequence such as to restore the sequence of data bits re-arrayed by the first interleaving means to the bit sequence of the data as encoded by the modulation encoding means, modulation decoding means for modulation decoding the data supplied from the deinterleaving means, and second interleaving means for interleaving data corresponding to a difference between data output by the modulation decoding means and data output by the deinterleaving means based on the same interleaving position information as that of the first interleaving means for re-arraying the sequence of the difference data.
- In the data recording and reproducing apparatus, according to the present invention, if data is to be recorded on a recording medium, the data supplied from the modulation encoding means is interleaved by first interleaving means to re-array the data sequence, whereas, if data recorded on the recording medium is to be reproduced, data given as a difference between second interleaving means for interleaving data corresponding to a difference between data output by the modulation decoding means and data output by the deinterleaving means based on the same interleaving position information as that of said first interleaving means is interleaved and re-arrayed, so that high performance encoding may be achieved, at the same time as efficient decoding may be achieved by exploiting the soft information for the entire decoding for the code, thus significantly lowering the decoding error rate.
- In yet another aspect, the present invention provides a data recording and reproducing method for recording and reproducing data for a recording medium, in which the method includes, as a recording system for recording data on the recording medium, a modulation encoding step for applying predetermined modulation encoding to input data, and a first interleaving step for interleaving data supplied from the modulation encoding step for re-arraying the data sequence, and in which the method also includes, as a reproducing system for reproducing data recorded on the recording medium, a deinterleaving step for interleaving the input data in its sequence such as to restore the sequence of data bits re-arrayed by the first interleaving step to the bit sequence of the data as encoded by the modulation encoding step, a modulation decoding step for modulation decoding the data supplied from the deinterleaving step, and a second interleaving step for interleaving data corresponding to a difference between data decoded in the modulation decoding step and data re-arrayed in the deinterleaving step based on the same interleaving position information as that of the first interleaving step for re-arraying the sequence of the difference data.
- In the data recording and reproducing method, according to the present invention, if data is to be recorded on a recording medium, the data supplied from the modulation encoding step is interleaved by the first interleaving step to re-array the data sequence, whereas, if data recorded on the recording medium is to be reproduced, data given as a difference between second interleaving means for interleaving data corresponding to a difference between data output by the modulation decoding means and data output by the deinterleaving means based on the same interleaving position information as that of said first interleaving means is interleaved and re-arrayed, so that high performance encoding may be achieved, at the same time as efficient decoding may be achieved by exploiting the soft information for the entire decoding for the code, thus significantly lowering the decoding error rate.
- FIG. 1 illustrates an input/output example of a conventional modulation encoder.
- FIG. 2 is a block diagram showing the structure of a conventional modulation decoder.
- FIG. 3 is a block diagram showing the structure of another conventional modulation decoder.
- FIG. 4 is a block diagram showing the structure of a conventional magnetic recording and/or reproducing apparatus.
- FIG. 5 illustrates an input/output example in an interleaver applied to a recording system of a magnetic recording and/or reproducing apparatus shown as a first embodiment of the present invention.
- FIG. 6 illustrates the operation of an interleaver used in a recording system of the magnetic recording and/or reproducing apparatus shown in FIG. 5.
- FIG. 7 illustrates an input/output example in a decoder applied to a reproducing system of the magnetic recording and/or reproducing apparatus shown in FIG. 5.
- FIG. 8 is a block diagram for illustrating the structure of a decoder used in the reproducing system of the magnetic recording and/or reproducing apparatus shown in FIG. 5.
- FIG. 9 is a block diagram for illustrating the structure of the recording and/or reproducing apparatus shown in FIG. 5.
- FIG. 10 is a block diagram for illustrating the structure of a channel and a modulation turbo decoder provided in the reproducing system of the recording and/or reproducing apparatus shown in FIG. 5.
- FIG. 11 illustrates the status transition diagram for generating codes satisfying the (d, k)=(0, 2) limitations.
- FIG. 12 illustrates the trellis when status transition has occurred thrice in accordance with the status transition diagram shown in FIG. 11.
- FIG. 13 illustrates the trellis constructed on branch selection from the trellis shown in FIG. 12.
- FIG. 14 is a block diagram showing the structure of an encoder used in a recording system of a magnetic recording and/or reproducing apparatus shown as a second embodiment of the present invention.
- FIG. 15 is a block diagram for illustrating the structure of the magnetic recording and/or reproducing apparatus.
- FIG. 16 is a block diagram for illustrating the structure of the channel and a modulation turbo decoder provided in a reproducing system of the magnetic recording and/or reproducing apparatus.
- Referring to the drawings, preferred embodiments of the present invention will be explained in detail.
- The present embodiment is directed to a magnetic recording and/or reproducing apparatus made up of a recording system for recording data on a recording medium of the magnetic recording system, such as a hard disc or a so-called DVCR (digital video cassette recorder), and a reproducing system for reproducing data recorded on these recording mediums.
- This magnetic recording and/or reproducing apparatus includes, in its recording system, an interleaver downstream of a modulation encoder, adapted for modulating signals, and executes encoding by so-called serial concatenated coding between a modulation encoder and a precoder, adapted for performing filtering on signals, in such a manner as to compensate for channel characteristics. Moreover, the magnetic recording and/or reproducing apparatus uses, on the reproducing side, a decoder for the channel and a decoder for modulation decoding the modulation encoded signals, that is an SISO (soft input soft output) type decoder, fed with soft input data to output soft output data, and iteratively executes decoding between these two decoders. This decoding is termed turbo decoding. That is, the magnetic recording and/or reproducing apparatus applies the encoding by the serial concatenated code and turbo decoding, known as the encoding method and decoding method giving the performance close to the Shannon limit as set by what is called the Shannon's theorem on the channel coding, to a recording and/or reproducing system performing data recording and/or reproduction for a recording medium.
- First, the magnetic recording and/or reproducing apparatus as a first embodiment is explained. Here, the interleaver, applied to the recording system of this magnetic recording and/or reproducing apparatus, is explained by referring to FIGS. 5 and 6.
- An
interleaver 10, shown in FIG. 5, interleaves data, encoded by block modulation by a modulation encoder provided on a pre-stage of theinterleaver 10, on the modulation code block basis, that is on the symbol basis, to re-array the bits making up the data. For example, if theinterleaver 10 re-arrays respective bits of data modulation-encoded to generate 3 output bits for 2 input bits in accordance with a conversion table shown in the following Table 3, theinterleaver 10 re-arrays an input signal, fed in a unit of three bits, as a modulation encoder block unit, in a unit of three bits, as shown in FIG. 6, to generate an output signal:TABLE 3 Example of Conversion Table input bits output bits 00 011 01 101 10 111 11 110 - More specifically, the
interleaver 10 holds the interleaving position information of data determined on the basis of generated random numbers in e.g., a ROM (read-only memory), and re-arrays the input signal on the modulation code block basis, based on the interleaving position information. For example, theinterleaver 10 holds the interleaving position information of data making up an input signal, and re-arrays the bits on the modulation encoding block basis, in accordance with the interleaving position information, at a timing of generation of the bit string made up of N bits, where N is an optional natural number, to output the re-arrayed bits as an output signal at a preset timing. - The decoder for modulation-decoding the modulation encoded signals, as a SISO type decoder applied to the reproducing system of the magnetic recording and/or reproducing apparatus, is explained with reference to FIGS. 7 and 8. It should be noted that, although the
decoders - A
decoder 20, shown in FIG. 7, decodes data encoded by block modulation, with the code rate R=k/n, where k is the number of input bits and n is the number of bits for modulation coding. - When fed with a reception signal R as the soft input, the
decoder 20 calculates the probability P (Ri=0|R) that the respective bits of this reception signal R are each “0” and the probability P (Ri=1|R) that the respective bits of this reception signal R are each “1”. Ultimately, thedecoder 20 calculates a posterior probability information P (Mi=0|R) and P (Mi=1|R), as a soft decision value for a modulation code block M represented by M=(M0, M1, . . . , Mn−1), and/or a posterior probability information P (Ci=0|R) and P (Ci=1|R), as a soft decision value for a modulation code input block C represented by C=(C0, C1, . . . , Ck−1), to output the so-calculated information. - Instead of individually outputting the aforementioned posterior probability information, the decoder is also able to output the logarithmic value of the ratio of the posterior probability information, that is log(P(Mi=1|R)/P(Mi=0|R)) or log(P(Ci=1|R)/P(Ci=0|R)). These log values are routinely termed the log likelihood ratio and here denote the likelihood of the modulating code block M and the modulating code input block C on the occasion of inputting the reception signal R.
- The decoder may also be fed with the priori probability information P (Ci=0) and P (Ci=1) for a modulation code input block C, instead of being fed with the aforementioned reception signal R.
- Specifically, the decoder may, for example, be configured as shown in FIG. 8. In the following explanation, it is assumed that, for generating a three-bit output for a two-bit input, data to be decoded has been encoded in accordance with the conversion table shown in Table 3 given above.
- The
modulation decoder 30, shown in FIG. 8, includes six likelihood calculating circuits 31 1, 31 2, 31 3, 31 4, 31 5 and 31 6, as means for calculating the likelihood of each reception bit, four adders 32 1, 32 2, 32 3 and 32 4 for summing the data, four log-sum circuits 33 1, 33 2, 33 3 and 33 4 for performing the operations of log (eA+eB) on the two data A and B, four adders 34 1, 34 2, 34 3 and 34 4 for summing two data, five comparators 35 1, 35 2, 36 1, 36 2 and 36 3 for taking the ratio of the two data, coefficient calculating circuits 37 1, 37 2 and 37 3 for calculating coefficients for respective elements in the modulation encoding block M and three adders 38 1, 38 2 and 38 3 for adding two data. It is noted that the number six of the likelihood calculating circuits is derived from three bits multiplied by 2 equals to six bits. - The likelihood calculating circuits31 1, 31 2, 31 3, 31 4, 31 5 and 31 6 are respectively fed with respective reception bits in a reception signal D31 (R) to calculate the likelihood of the respective reception bits.
- That is, the likelihood calculating circuits31 1 is fed with the 0th bit of the three-bit reception signal D31 to calculate the log probability value D32 1 (logP(R0=0|R)) corresponding to the log value of the probability that this bit is “0”. The likelihood calculating circuits 31 1 sends the generated log probability value D32 1 to the adder 32 1.
- The likelihood calculating circuits31 2 is fed with the 0th bit of the three-bit reception signal D31 to calculate the log probability value D32 2 (logP(R0=1|R)) corresponding to the log value of the probability that this bit is “1”. The likelihood calculating circuits 31 2 sends the generated log probability value D32 2 to the adders 32 2, 32 3 and 32 4 and to the comparator 36 1.
- Then, the likelihood calculating circuits31 3 is fed with the first bit of the three-bit reception signal D31 to calculate the log probability value D32 3 (logP(R1=0|R)) corresponding to the log value of the probability that this bit is “0”. The likelihood calculating circuits 31 3 sends the generated log probability value D32 3 to the adder 32 2 and to the comparator 36 2.
- The likelihood calculating circuits31 4 is fed with the first bit of the three-bit reception signal D31 to calculate the log probability value D32 4 (logP(R1=1|R)) corresponding to the log value of the probability that this bit is “1”. The likelihood calculating circuits 31 4 sends the generated log probability value D32 4 to the adder 32 1, 32 3 and 32 4 and to the comparator 36 2.
- Then, the likelihood calculating circuits31 5 is fed with the second bit of the three-bit reception signal D31 to calculate the log probability value D32 5 (logP(R2=0|R)) corresponding to the log value of the probability that this bit is “0”. The likelihood calculating circuits 31 5 sends the generated log probability value D32 5 to the adder 32 4 and to the comparator 36 3.
- The likelihood calculating circuits31 6 is fed with the second bit of the three-bit reception signal D31 to calculate the log probability value D32 6 (logP(R2=1|R)) corresponding to the log value of the probability that this bit is “1”. The likelihood calculating circuits 31 6 sends the generated log probability value D32 6 to the adders 32 1, 32 2 and 32 3 and to the comparator 36 3.
- The adder D32 1 sums the log probability value D32 1, supplied from the likelihood calculating circuits 31 1, the log probability value D32 4, supplied from the likelihood calculating circuits 31 4 and the log probability value D32 6, supplied from the likelihood calculating circuits 31 6, to generate the likelihood value D33 1. That is, this likelihood value D33 1 is not other than the probability represented by log P(R|M0M1M2=011). The adder D32 1 sends the generated likelihood value D33 1 to the log-sum circuits 33 1, 33 3.
- The adder D32 2 sums the log probability value D32 2, supplied from the likelihood calculating circuits 31 2, the log probability value D32 3, supplied from the likelihood calculating circuits 31 3 and the log probability value D32 6, supplied from the likelihood calculating circuits 31 6 to generate the likelihood value D33 2. That is, this likelihood value D33 2 is not other than the probability represented by log P(R|M0M1M2=101). The adder D32 2 sends the generated likelihood value D33 2 to the log-sum circuits 33 1, 33 4.
- The adder D32 3 sums the log probability value D32 2, supplied from the likelihood calculating circuits 31 2, the log probability value D32 4, supplied from the likelihood calculating circuits 31 4, and the log probability value D32 6, supplied from the likelihood calculating circuits 31 6, to generate the likelihood value D33 3. That is, this likelihood value D33 3 is not other than the probability represented by log P(R|M0M1M2=111). The adder D32 3 sends the generated likelihood value D33 3 to the log-sum circuits 33 2, 33 3.
- The adder D32 4 sums the log probability value D32 2, supplied from the likelihood calculating circuits 31 2, the log probability value D32 4, supplied from the likelihood calculating circuits 31 4 and the log probability value D32 5, supplied from the likelihood calculating circuits 31 5, to generate the likelihood value D33 4. That is, this likelihood value D33 4 is not other than the probability represented by log P(R|M0M1M2=110). The adder D32 4 sends the generated likelihood value D33 4 to the log-swn circuits 33 2, 33 4.
- The log-sum circuit33 1 performs an operation shown by the equation (4):
- log(e log P(R|M 0 M 1 M 2 =011) +e log P(R|M 0 M 1 M 2 =101))=log(P(R|M 0 M 1 M 2=011)+P(R|M 0 M 1 M 2=101)) (4)
- on the likelihood value D33 1 supplied from the adder 32 1 and on the likelihood value D33 2 supplied from the adder 32 2 to generate a likelihood value D34 1. The log-sum circuit 33 1 sends the so-generated likelihood value D34 1 to the adder 34 1.
- The log-sum circuit33 2 performs an operation shown by the equation (5):
- log(e log P(R|M 0 M 1 M 2 =111) +e log P(R|M 0 M 1 M 2 =110))=log(P(R|M 0 M 1 M 2=111)+P(R|M 0 M 1 M 2=110)) (5)
- on the likelihood value D33 3 supplied from the adder 32 3 and on the likelihood value D33 4 supplied from the adder 32 4 to generate a likelihood value D34 2. The log-sum circuit 33 2 sends the so-generated likelihood value D34 2 to the adder 34 2.
- The log-sum circuit33 3 performs an operation shown by the equation (6):
- log(e log P(R|M 0 M 1 M 2 =011) +e log P(R|M 0 M 1 M 2 =111))=log(P(R|M 0 M 1 M 2=011)+P(R|M 0 M 1 M 2=111)) (6)
- on the likelihood value D33 1 supplied from the adder 32 1 and on the likelihood value D33 3 supplied from the adder 32 3 to generate a likelihood value D34 3. The log-sum circuit 33 3 sends the so-generated likelihood value D34 3 to the adder 34 3.
- The log-sum circuit33 4 performs an operation shown by the equation (7):
- log(e log P(R|M 0 M 1 M 2 =101) +e log P(R|M 0 M 1 M 2 =110))=log(P(R|M 0 M 1 M 2=101)+P(R|M 0 M 1 M 2=110)) (7)
- on the likelihood value D33 2 supplied from the adder 32 2 and on the likelihood value D33 4 supplied from the adder 32 4 to generate a likelihood value D34 4. The log-sum circuit 33 4 sends the so-generated likelihood value D34 4 to the adder 34 4.
- The adder34 1 sums the likelihood value D34 1 supplied from the log-sum circuit 33 1 and the log priori probability D35 1 (logP(C0=0)) for an input bit, fed from outside, to generate the log probability value D36 1. This log probability value D36 1 denotes the probability shown by the following equation (8):
- logP(C 0=0|R)=log {P(R|M 0 M 1 M 2=011)+(R|M 0 M 1 M 2=101)}+logP(C 0=0) (8).
- The adder34 1 sends the generated log probability value D36 1 to a comparator 35 1.
- The adder34 2 sums the likelihood value D34 2 supplied from the log-sum circuit 33 2 and the log priori probability D35 2 (logP(C0=1)) for an input bit, input from outside, to generate the log probability value D36 2. This log probability value D36 2 denotes the probability shown by the following equation (9):
- logP(C 0=1|R)=log {P(R|M 0 M 1 M 2=111)+(R|M 0 M 1 M 2=110)}+logP(C 0=1) (9).
- The adder34 2 sends the generated log probability value D36 2 to a comparator 35 1.
- The adder34 3 sums the likelihood value D34 3 supplied from the log-sum circuit 33 3 and the log priori probability D35 3 (logP(C1=0)) for an input bit, input from outside, to generate the log probability value D36 3. This log probability value D36 3 denotes the probability shown by the following equation (10):
- logP(C 1=0|R)=log {P(R|M 0 M 1 M 2=011)+(R|M 0 M 1 M 2=111)}+logP(C 1=0) (10).
- The adder34 3 sends the generated log probability value D36 3 to the comparator 35 2.
- The adder34 4sums the likelihood value D34 4 supplied from the log-sum circuit 33 4 and the log priori probability D35 4 (logP(C1=1)) for an input bit, input from outside, to generate the log probability value D36 4. This log probability value D36 4 denotes the probability shown by the following equation (11):
- logP(C 1=1|R)=log {P(R|M 0 M 1 M 2=101)+(R|M 0 M 1 M 2=1110)}+logP(C 1=1) (11).
- The adder34 4 sends the generated log probability value D36 4 to a comparator 35 2.
- The comparator35 1 takes the ratio of the log probability value D36 1 supplied from the adder 34 1 and the log probability value D36 2 supplied from the adder 34 2 to generate the decoded log posterior probability ratio D37 1 (log(P(C0=1|R)/P(C0 =0|R))) which is output to outside.
- The comparator35 2 takes the ratio of the log probability value D36 3 supplied from the adder 34 3 and the log probability value D36 4 supplied from the adder 34 4 to generate the decoded log posterior probability ratio D37 2 (log(P(C1=1|R)/P(C1=0|R))) which is output to outside.
- The comparator36 1 takes the ratio of the log probability value D32 1 supplied from the likelihood calculating circuit 31 1 and the log probability value D32 2 supplied from the likelihood calculating circuit 31 2 to generate the log posterior probability ratio D38 1 (log(P(M0=1|R)/P(M0=0|R))) which is output to the adder 38 1.
- The comparator36 2 takes the ratio of the log probability value D32 3 supplied from the likelihood calculating circuit 31 3 and the log probability value D32 4 supplied from the likelihood calculating circuit 31 4 to generate the log posterior probability ratio D38 2 (log(P(M1=1|R)/P(M1=0|R))) which is output to the adder 38 2.
- The comparator36 3 takes the ratio of the log probability value D32 5 supplied from the likelihood calculating circuit 31 5 and the log probability value D32 6 supplied from the likelihood calculating circuit 31 6 to generate the log posterior probability ratio D38 3 (log(P(M2=1|R)/P(M2=0|R))) which is output to the adder 38 3.
-
- that is a coefficient α for the modulation code M0 equivalent to the 0th bit making up the three-bit reception signal D31, based on the log priori probability D35 1, D35 2, D35 3 and D35 4 for the input bit supplied from outside, to generate a M0 coefficient signal D39 1. The coefficient calculating circuit 37 1 sends the generated M0 coefficient D39 1 to the adder 38 1.
-
- that is a coefficient β for the modulation code M1 equivalent to the first bit making up the three-bit reception signal D31, based on the log priori probability D35 1, D35 2, D35 3 and D35 4 for the input bit supplied from outside, to generate a M1 coefficient signal D39 2. The coefficient calculating circuit 37 2 sends the generated M1 coefficient D39 2 to the adder 38 2.
-
- that is a coefficient γ for the modulation code M2 equivalent to the second bit making up the three-bit reception signal D31, based on the log priori probability D35 1, D35 2, D35 3 and D35 4 for the input bit supplied from outside, to generate a M2 coefficient signal D39 3. The coefficient calculating circuit 37 3 sends the generated M2 coefficient D39 3 to the adder 38 3.
- The adder38 1 sums the log posterior probability ratio D38 1, supplied from the comparator 36 1, to the M0 coefficient signal D39 1 supplied from the coefficient calculating circuit D37 1. The adder 38 1 outputs the decoded channel log posterior probability ratio signal D40 1(log (P(M0=1|R)/P(M0=0|R))) to outside.
- The adder38 2 sums the log posterior probability ratio D38 2, supplied from the comparator 36 2, to the M1 coefficient signal D39 2 supplied from the coefficient calculating circuit D37 2. The adder 38 2 outputs the decoded channel log posterior probability ratio signal D40 2(log (P(M1=1|R)/P(M1=0|R))) to outside.
- The adder38 3 sums the log posterior probability ratio D38 3, supplied from the comparator 36 3, to the M2 coefficient signal D39 3 supplied from the coefficient calculating circuit D37 3. The adder 38 3 outputs the decoded channel log posterior probability ratio signal D40 3(log (P(M2=1|R)/P(M2=0|R))) to outside.
- The
decoder 30, having the components as described above, has the likelihood calculating circuits 31 1, 31 2, 31 3, 31 4, 31 5 and 31 6 for calculating the likelihood of respective reception bits in the reception signals D31 (R) taking analog values under the effect of the noise generated in the course of transmission, as soft input, that is the respective output codewords on the modulation coder side. By these likelihood calculating circuits 31 1, 31 2, 31 3, 31 4, 31 5 and 31 6, themodulation decoder 30 finds the likelihood of the respective codewords and uses the likelihood values, thus found, to find the posterior probability information straightforwardly, as soft decision values for the input and output bits on the modulation coder side. - Meanwhile, the
decoder 30 is fed from outside with log priori probability D35 1, D35 2, D35 3, D35 4. If the probability of the respective bits making up the binary signal input to the modulation coder, not shown, being “0”, is equivalent to the same probability being “1”, there is no necessity of inputting the log priori probability D35 1, D35 2, D35 3, D35 4, it being only necessary to handle as if the values of these log priori probability D35 1, D35 2, D35 3, D35 4 are all equal to zero. - Although the above explanation is based on the assumption that the
modulation decoder 30 decodes data obtained on modulation-coding a 2-bit input to a 3-bit output, the modulation decoder is not limited as to the number of bits of the input or the output and may be similarly configured in keeping with the number of bits of the input or the output used. - Referring to FIG. 9, the magnetic recording and/or reproducing apparatus, employing this interleaver and decoder, is hereinafter explained.
- A magnetic recording and/or reproducing
apparatus 50, shown in FIG. 9, includes, as a recording system for recording data on arecording medium 70, anerror correction coder 51 for error correction coding input data, amodulation coder 52 for modulation coding input data, aninterleaver 53 for re-arraying the input data, aprecoder 54 for filtering the input data for compensating for channel characteristics, a writecurrent driver 55 for converting respective bits of the input data into write current values, and awrite head 56 for recording data on arecording medium 70. - The
error correction coder 51, as error correction encoding means, applies error correction coding to the input data D51. Theerror correction coder 51 sends the error correction encoded data D52, generated on error correction coding, to the downstreamside modulation encoder 52. - The
modulation encoder 52, as modulation encoding means, applies predetermined modulation coding to the error correction encoded data D52, supplied from theerror correction coder 51, to generate modulation encoded data D53 as a string subjected to limitations. Themodulation encoder 52 sends the so-generated modulation encoded data D53 to thedownstream side interleaver 53. - The
interleaver 53, as (first) interleaving means, is constructed as theaforementioned interleaver 10, interleaving the modulation encoded data D53, encoded with block modulation by themodulation encoder 52, on the modulation encoding block basis, to re-array the sequence of bits making up the modulation encoded data D53. Theinterleaver 53 sends the generated interleaved data D54 to thedownstream side precoder 54. - The
precoder 54 as precoding means filters the interleaved data D54, supplied from theinterleaver 53, in such a manner as to compensate for channel characteristics from the data writing to therecording medium 70 to the outputting thereof in theequalizer 58 in the reproducing system, thereby generating a precode signal D55 as a binary signal. For example, if the channel has 1-D characteristics theprecoder 54 performs filtering F represented by the following equation (15): - F=1/(1⊕D) (15)
- where ⊕ denotes exclusive-OR. The
precoder 54 sends the generated precode signal D55 to the downstream side writecurrent driver 55. - The write
current driver 55 converts respective bits of the precode signal D55, supplied from theprecoder 54, into the write current value Is, so that 0 and 1 will be converted to −Is and +Is (0→−Is, 1→+Is), respectively, to generate a write current signal D56. The writecurrent driver 55 sends the so-generated write current signal D56 to the downstreamside write head 56. - The
write head 56 routes a write magnetic signal D57, conforming to the write current signal D56, supplied from the writecurrent driver 55, to therecording medium 70 to record data thereon. - When recording data on the
recording medium 70, the recording system in this magnetic recording and/or reproducingapparatus 50 applies error correction coding to the input data D51, by theerror correction coder 51, to produce error correction coded data D52, which then is modulation-encoded in a predetermined fashion by the modulation-coder 52. The so-produced modulation encoded data D53 is interleaved by theinterleaver 53 on the modulation encoding block basis to produce precode signal D55 by theprecoder 54. - The recording system records the precode signal D55, generated by the
precoder 54, on therecording mediwn 70, through thewrite head 55 and thewrite head 56. - The recording system in the magnetic recording and/or reproducing apparatus includes the
interleaver 53 downstream of themodulation encoder 52, and executes serial concatenated coding between themodulation encoder 52 and theprecoder 54 to realize high performance encoding as encoding downstream of the error correction coding and encoding for the channel. - On the other hand, the magnetic recording and/or reproducing
apparatus 50 includes, as a reproducing system for reproducing the data recorded on therecording medium 70, areadout head 57 for reading out data recorded on therecording medium 70, anequalizer 58 for equalizing input data, again adjustment circuit 59 for adjusting the gain of the input data, an analog/digital (A/D)converter 60 for converting analog data into digital data, atiming reproducing circuit 61 for reproducing clocks, a gainadjustment control circuit 62 for controlling thegain adjustment circuit 59, a channel andmodulation turbo decoder 63 for applying turbo soft decoding to the input data, and an error correctingsoft decoder 64 for applying error correcting soft decoding to the input data. - The
readout head 57 reads out a readout magnetization signal D58 from the recording medium and generates a readout current signal D59 corresponding to this readout magnetization signal D58. Thereadout head 57 sends the generated readout current signal D59 to thedownstream side equalizer 58. - The
equalizer 58 equalizes the readout current signal D59, supplied from thereadout head 57, so that the channel response from data writing on therecording medium 70 in the recording system up to outputting thereof in theequalizer 58 will be of pre-set characteristics, such as 1-D, to generate an equalized signal D60. Theequalizer 58 sends the generated equalized signal D60 to the downstream sidegain adjustment circuit 59. - The
gain adjustment circuit 59 adjusts the gain of the equalized signal D60, supplied from theequalizer 58, based on the gain adjustnent control signal D64 supplied from the gainadjustment control circuit 62, to generate a gain adjustment signal D61. Thegain adjustment circuit 59 sends the generated gain adjustment signal D61 to the downstream side A/D converter 60. - The A/
D converter 60 samples the gain adjustment signal D61, supplied from thegain adjustment circuit 59, based on the clock signal D63 supplied from thetiming generating circuit 61, to digitize the gain adjustment signal D61 to generate a digital channel signal D62. The A/D converter 60 sends the so-generated digital channel signal D62 to thetiming generating circuit 61, gainadjustment control circuit 62 and to the channel andmodulation turbo decoder 63. - The
timing generating circuit 61 regenerates clocks from the digital channel signal D62, supplied from the A/D converter 60, to generate clock signals D63. Thetiming generating circuit 61 routes the generated clock signals D63 to the A/D converter 60. - Based on the digital channel signal D62, supplied from the A/
D converter 60, the gainadjustment control circuit 62 generates a gain adjustment control signal D64, which is a control signal used for maintaining the amplitude of the equalized signal D60 at an expected value. The gainadjustment control circuit 62 sends the generated gain adjustment control signal D64 to thegain adjustment circuit 59. - The channel and
modulation turbo decoder 63 concatenates SISO decoders, constructed as the above-mentioneddecoders modulation turbo decoder 63, explained later in detail, is fed with the digital channel signal D62, supplied from the A/D converter 60, to perform turbo decoding, and routes a so-generated turbo decoded signal D65 to the post-stage error correctingsoft decoder 64. - The error correcting
soft decoder 64, as error correction soft decoding means, applies the so-called BCJR (Bahl, Cocke, Jelinek and Rahiv) algorithm or the SOVA (soft output viterbi algorithm) to the turbo decoded signal D65, supplied from the channel andmodulation turbo decoder 63, to output the soft-decoded signal as soft or hard output data D66. - The channel and
modulation turbo decoder 63 will be explained in detail by referring to FIG. 10. - Referring to FIG. 10, the channel and
modulation turbo decoder 63 includes achannel SISO decoder 81, as an SISO type decoder for decoding the channel response from the pre-stage of theprecoder 54 in the recording system up to the outputting stage of theequalizer 58 in the reproducing system, adeinterleaver 83 for restoring the sequence of the input data to the original sequence, amodulation SISO decoder 84, as a decoder of the SISO type for modulation decoding the input data, adeinterleaver 86 for re-arraying the input data, achangeover switch 87 for switching the data input as the priori probability information to information bits and twodifference taking units - The
channel SISO decoder 81, as channel decoding means, is constructed as theaforementioned decoders channel SISO decoder 81 is fed with the digital channel signal D62, as a soft input supplied from the A/D converter 60, and with the priori probability information D78, which is the priori probability information D76 for an information bit as a soft input supplied from theinterleaver 86, or the priori probability information D77 for an information bit which is of a value “0”, as selected by thechangeover switch 87, and performs soft output decoding, based on the channel response Rch from the pre-stage of theprecoder 54 in the recording system up to an output in theequalizer 58, represented by the following equation (13): - R ch=(1−D)/(1⊕D) (16)
- where ⊕ denotes exclusive OR, in accordance with the aforementioned BCJR algorithm or SOVA. If the interleaved data D54 prior to the precoding by the
precoder 54 is represented as C(t), with 0≦t≦N, thechannel SISO decoder 81 computes the log posterior probability ratio log (P(C(t)=1)/P(C(t)=0)), as the posterior probability information for C(t), to route this log posterior probability ratio as the channel decoded signal D71 to the downstream sidedifference taking unit 82. - The
channel SISO decoder 81 is not limited to theaforementioned decoders channel SISO decoder 81 is constructed as an SISO decoder. For example, it is sufficient if thechannel SISO decoder 81 performs soft output decoding, in accordance with the aforementioned BCJR algorithm or SOVA, based on the trellis corresponding to the channel response. - The
difference taking unit 82 takes the difference between the channel decoded signal D71, as a soft input, supplied from thechannel SISO decoder 81, and the priori probability information D76, as a soft input, supplied from theinterleaver 86, to output data represented by ths difference value as a soft output to thepost-stage deinterleaver 83, as the channel extrinsic information signals D72 as the extrinsic information to an information bit as found by the code constraint condition. Meanwhile, this channel extrinsic information signals D72 corresponds to the interleaved data D54 as interleaved by theinterleaver 53 of the recording system. - The
deinterleaver 83, as deinterleaving means, deinterleaves the channel extrinsic information signals D72, as a soft input, supplied from thedifference taking unit 82, in order to restore the bit sequence of the interleaved data D54 from theinterleaver 53 of the recording system to the bit sequence of the original modulation encoded data D53. Thedeinterleaver 83 sends the deinterleaved data to themodulation SISO decoder 84 and to thedifference taking unit 85 as the deinterleaved signal D73 which is the priori probability information to the code bit in themodulation SISO decoder 84. - The
modulation SISO decoder 84 as modulation decoding means is constructed as theaforementioned decoders modulation coder 52 of the recording system with the code rate R=K/N, with the modulation encoded data D53 following modulation encoding by themodulation coder 52 being M(t) (0≦t<N) and with the error correction coded data D52 prior to modulation encoding by themodulation coder 52 being E(t) (0≦t<K). Themodulation SISO decoder 84, fed as an input with the deinterleaved signal D73 from thedeinterleaver 83, calculates the log posterior probability ratio log (P(M(t)=1)/P(M(t)=0)), as the posterior probability information for M(t), with the deinterleaved signal D73 as an input from the channel, and sends the log posterior probability ratio as the modulation channel decoded signal D74 to thedifference taking unit 85. Themodulation SISO decoder 84 also calculates the log posterior probability ratio log (P(E(t)=1)/P(E(t)=0)), as the posterior probability information for E(t), to route the log posterior probability ratio as the turbo decoded signal D65 to the error correctingsoft decoder 64. - The
difference taking unit 85 finds a difference value between the modulation channel decoded signal D74, as a soft input, supplied from themodulation SISO decoder 84, and the deinterleaved signal D73 as a soft input from thedeinterleaver 83, and outputs data given as this difference value to thepost-stage interleaver 86 as a soft output as the modulated extrinsic information signals D75 as the extrinsic information to the code bit as found by the constraint condition. - The
interleaver 86, as the second interleaving means, interleaves the modulated extrinsic information signals D75, as a soft input fed from thedifference taking unit 85, based on the same interleaving position information as that of theinterleaver 53 of the recording system. Theinterleaver 86 sends the interleaved data to thechannel SISO decoder 81 and to thedifference taking unit 82 as being the priori probability information signal D76 for the information bit in thechannel SISO decoder 81. - In the initial stage of the decoding, the
changeover switch 87 is set to the fixed terminal a supplying avalue 0 corresponding to the priori probability information signal D77 to select the priori probability information signal D77 as being the priori probability information signal D78 for an information bit in thechannel SISO decoder 81. Thechangeover switch 87 then is set to a fixed terminal b supplying the priori probability information signal D76 supplied from theinterleaver 86 to select the priori probability information signal D76 as being the priori probability information signal D78. - The channel and
modulation turbo decoder 63, is provided with themodulation SISO decoder 84 and thechannel SISO decoder 81, as counterparts to themodulation coder 52 and theprecoder 54 of the recording system, respectively, as described above, to decompose the code of high decoding complexity into elements with lower decoding complexity, such as to sequentially improve characteristics by the interaction between thechannel SISO decoder 81 and themodulation SISO decoder 84. If fed with the digital channel signal D62, as a soft input, from the A/D converter 60, the channel andmodulation turbo decoder 63 iterates the decoding operations from thechannel SISO decoder 81 to the modulation SISO decoder 84 a pre-set number of times, such as several to tens of times, to route the soft-output log posterior probability ratio, obtained on decoding a pre-set number of times, as the turbo decoded signal D65 to the post-stage error correctingsoft decoder 64. - In reproducing data recorded on the
recording medium 70, the reproducing system of the magnetic recording and/or reproducingapparatus 50 turbo-decodes the soft-input digital channel signal D62, generated through thereadout head 57,equalizer 58,gain adjustment circuit 59 and the A/D converter 60, by the channel andmodulation turbo decoder 63, to generate the turbo decoded signal D65 corresponding to the error correction coded data D52 input to themodulation coder 52 in the recording system. - This reproducing system soft-decodes the turbo decoded signal D65, generated by the channel and
modulation turbo decoder 63, for error correction codes, by the error correctingsoft decoder 64, to output data as resulting soft output directly to outside as output data D66, or binary-codes the soft-output data to generate hard-output data D66, which is issued to outside. - The reproducing system of the magnetic recording and/or reproducing
apparatus 50 is provided in this manner with the channel andmodulation turbo decoder 63 and performs turbo decoding between themodulation SISO decoder 84 and thechannel SISO decoder 81 corresponding to themodulation coder 52 and theprecoder 54 of the recording system to realize decoding in meeting with the channel response and the modulation encoding. - In the above-described magnetic recording and/or reproducing
apparatus 50, in which theinterleaver 53 is provided in the recording system on the post-stage of themodulation coder 52 to execute encoding by serial concatenated code between themodulation coder 52 and theprecoder 54, while it is provided on the reproducing system with the channel andmodulation turbo decoder 63 to effect turbo decoding to realize high performance coding. In addition, turbo decoding with high efficiency can be realized by exploiting soft information for the entire decoding processing for the code, thus eliminating the necessity of diminishing the information. The result is the appreciably lowered decoding error rate. - The second embodiment of the magnetic recording and/or reproducing apparatus is now explained. The magnetic recording and/or reproducing apparatus executes encoding as correlation is afforded to fore and aft side data instead of coding/decoding on the block basis. In addition, the magnetic recording and/or reproducing apparatus performs trellis decoding conforming to the constraint condition.
- An interleaver used for the recording system of the magnetic recording and/or reproducing apparatus is first explained.
- An interleaver applied to the recording system, such a one may be used which is configured similarly to the
interleaver 10 shown in FIG. 5 and in which data is interleaved based on the modulation encoding block of the trellis to re-array the data bit sequence. It is assumed here that the bit sequence of the data from the modulation encoding of generating three output bits for two input bits in accordance with the conversion table shown in Table 3 by an interleaver. If the constraint condition to be met by the modulation encoded data is (d, k)=(0, 2) limitation, the interleaver generates a sequence meeting the (d, k)=(0, 4) limitation. - The interleaver is not limited to one interleaving the data based on the modulation encoding block of the trellis, such that any suitable interleaver interleaving the data such as to meet the pre-set constraint condition following interleaving may be used.
- Referring to FIGS.11 to 14, the encoder used in the recording system and the SISO decoder used for the reproducing system of the magnetic recording and/or reproducing apparatus is explained. It is noted that, although the coder and the decoder, used for modulation encoding and modulation decoding, respectively, are shown here, the coder and the decoder for the channel are configured in a similar fashion.
- The magnetic recording and/or reproducing apparatus performs modulation encoding and modulation decoding, based on a common trellis. Although the trellis structure is changed depending on limitations imposed on the modulation code, the modulation encoding and modulation decoding, satisfying the (d, k)=(0, 2) limitations, with the code rate R=2/3, is here explained.
- FIG. 11 shows a diagram showing the status transition for generating satisfying the (d, k)=(0, 2) limitations. In FIG. 11, labels affixed between the respective states indicate bits output in case of status transition. For example, if the status transition that has occurred is “S0→S1→S2”, an output bit string is “00”. The bit string output in case status transition has occurred in accordance with the aforementioned status transition diagram necessarily satisfies the (d, k)=(0, 2) limitations.
- Assume that the modulation encoding of outputting a 3 bit modulated code for a 2-bit input, with the code rate R=2/3. For generating the modulation code satisfying the (d, k)=(0, 2) limitations, it is apparently sufficient if status transition occurs thrice in accordance with the status transition diagram shown in FIG. 11, with the resulting output being a modulated code.
- The trellis when the status transition has occurred thrice in accordance with the status transition diagram shown in FIG. 11, that is, a diagram obtained on developing the status transition diagram along the time axis direction, is as shown in FIG. 12. For example, in the trellis shown in FIG. 12, a branch lying at an uppermost position indicates that there is one path starting at the status S2 and again getting to the status S2 after three status transitions, with a corresponding output being “100”.
- In case of modulation encoding of outputting 3-bit modulated code for a 2-bit input, 22=4 branches are selected from each state, these branches being then allocated to 2-bit inputs of “00, 01, 10, 11” to form a trellis in which an input is associated with an output. FIG. 13 shows a trellis formed on branch selection as described above. In FIG. 13, each label affixed between different states indicate an input/output. For example, in the trellis shown in FIG. 13, a branch S0→S2 indicates that, if “11” is input for the state S0, status transition occurs to the status S2, as “100” is output.
- The encoder, applied to the magnetic recording and/or reproducing apparatus, shown as the second embodiment, repeats the status transition for encoding, in accordance with the trellis formed by the above-described sequence of operations, to generate a modulated code string having correlation between input data. The encoder may be provided with components shown for example in FIG. 14.
- The
encoder 90, shown in FIG. 14, includes astate register 91 for holding the state of theencoder 90, a next-state calculating circuit 92, for calculating the next transition state, and an outputsignal calculating circuit 93 for calculating an output signal D94. - The
state register 91 is a 2-bit register holding 2 bits specifying the state of thecurrent encoder 90. Thestate register 91 sends a status signal D92, specifying the 2 bits indicating the current state, to the next-state calculating circuit 92 and to the outputsignal calculating circuit 93, as thestate register 91holds 2 bits indicating the next state corresponding to the next state signal D93 supplied from the next-state calculating circuit 92. - When fed with the input signal D91 and with the status signal D92, supplied from the
state register 91, the next-state calculating circuit 92 calculates the next state in acccordance with the following input/output correlating table 4:TABLE 4 Typical Input/Output Correlating Table status signals input signals next- state signals 0 00 0 0 01 1 0 10 1 0 11 2 1 00 1 1 01 0 1 10 0 1 11 2 2 00 2 2 01 0 2 10 0 2 11 1 3 00 0 3 01 0 3 10 0 3 11 0 - The next-
state calculating circuit 92 sends the next state signal D93 to thestate register 91. - If fed with the input signal D91 and with the status signal D92, supplied from the
state register 91, the outputsignal calculating circuit 93 calculates an output signal D94, in accordance with the following input/output correlating table 5:TABLE 5 Typical Input/Output Correlating Table status signals input signals output signals 0 00 111 0 01 110 0 10 010 0 11 100 1 00 110 1 01 011 1 10 111 1 11 100 2 00 100 2 01 101 2 10 111 2 11 110 3 00 111 3 01 111 3 10 111 3 11 111 - Meanwhile, this output signal D94 satisfies the (d, k)=(0, 2) limitations.
- When fed with the input signal D91, the
encoder 90 calculates the next state, using this input signal D91 and the status signal D92, by the next-state calculating circuit 92, for storage sequentially in thestate register 91. Theencoder 90 calculates an output signal D94, by the outputsignal calculating circuit 93, using the input signal D91 and the status signal D92, by the outputsignal calculating circuit 93, to output the so-calculated output signal D94. - Since there lacks the status S3 in the
encoder 90, if transition to the status S3 occurs before the resetting of theencoder 90, an output signal “111” is instantly output as an output signal D94, based on the Table 5, to realize the function of resetting to the state S0. - A decoder for modulation decoding the signal, encoded by the above-described encoder, applies the decoding, which is based on the BCJR or SOVA algorithm, in accordance with the trellis previously explained with reference to FIG. 13. With this decoder, the magnetic recording and/or reproducing apparatus is able to perform trellis decoding exploiting the signal correlation in the modulation encoder.
- In particular, if, in performing trellis decoding in the magnetic recording and/or reproducing apparatus, SISO decoding of the BCJR or SOVA algorithm is used in the decoder, the soft information can be output to the error correction decoding circuit provided downstream of the modulation decoder, thereby improving the decoding error rate.
- The magnetic recording and/or reproducing apparatus, employing this type of the encoder and the decoder, is hereinafter explained with reference to FIG. 15.
- The magnetic recording and/or reproducing
apparatus 100, shown in FIG. 15, includes, as a recording system for recording data on arecording medium 70, anerror correction encoder 101 for error correction encoding input data, amodulation encoder 101, amodulation encoder 102 for modulation encoding input data, aninterleaver 103 for re-arraying the input data in its sequence, aprecoder 104 for filtering input data for compensating its channel characteristics, a writecurrent driver 105 for converting respective bits of the input data into write current values, and awrite head 106 for recording data on therecording medium 70. - Similarly to the
error correction coder 51 in the magnetic recording and/or reproducingapparatus 50, theerror correction encoder 101, as error correcting encoding means, error correction encodes the input data D101. Theerror correction encoder 101 sends the error correction encoded data D102 to the downstreamside modulation encoder 102. - The
modulation encoder 102, as modulation encoding means, is configured as theaforementioned modulation encoder 90. Specifically, it is a modulation encoder for repeating status transitions in accordance with the trellis, by way of encoding, for generating a modulated code string exhibiting correlation between input data. Themodulation encoder 102 applies pre-set trellis modulation coding to the error correction coded data D102, supplied from theerror correction encoder 101, to generate modulated encoded data D103 as a string subjected to limitation. Themodulation encoder 102 sends the generated modulation encoded data D103 to thedownstream side interleaver 103. - The
interleaver 103, as (first) interleaving means, interleaves the modulated encoded data D103 in terms of the trellis modulation encoding block as a unit, to re-array the sequence of bits making up the modulated encoded data D103. Theinterleaver 103 sends the generated interleaved data D104 to thedownstream side precoder 104. - Similarly to the
precoder 54 of the aforementioned magnetic recording and/or reproducingapparatus 50, theprecoder 104 filters the interleaved data D104, supplied from theinterleaver 103, in such a manner as to compensate for channel characteristics from the data writing to therecording medium 70 to the output in theequalizer 108 in the reproducing system, thereby generating a precode signal D105 as a binary signal. Theprecoder 104 sends the so-generated precede signal D105 to the downstream side writecurrent driver 105. - Similarly to the write
current driver 55 in the aforementioned magnetic recording and/or reproducingapparatus 50, the writecurrent driver 105 converts respective bits of the precode signal D104, supplied from theprecoder 103, into the write current value Is, to generate a write current signal D106. The writecurrent driver 105 sends the generated write current signal D106 to a downstreamside write head 106. - Similarly to the
write head 56 in the aforementioned magnetic recording and/or reproducingapparatus 50, thewrite head 106 applies a magnetic write signal D107, corresponding to the write current signal D106 supplied from the writecurrent driver 105, to therecording medium 70, to record data thereon. - In recording data on the
recording medium 70, the recording system in the magnetic recording and/or reproducingapparatus 100 error correction encodes the input data D101 by theerror correction encoder 101. The recording system then applies pre-set trellis modulation encoding to error correction encoded data D102 by themodulation encoder 102 and interleaves the modulated encoded data D103 by theinterleaver 103 based on the pre-set trellis modulation encoding block to generate a precede signal D105 by theprecoder 104. - The recording system records the precode signal D105, generated by the
precoder 104, on therecording medium 70, by the writecurrent driver 105 and thewrite head 106. - The recording system of the magnetic recording and/or reproducing
apparatus 100, thus having theinterleaver 103 downstream of themodulation encoder 102, effects encoding by serial concatenated coding between themodulation encoder 102 and theprecoder 104 to realize high performance coding as modulation encoding and channel coding downstream of the error correction coding. - As the reproducing system for reproducing data recorded on the
recording medium 70, the magnetic recording and/or reproducingapparatus 100 includes areadout head 107 for reading out data recorded on therecording medium 70, anequalizer 108 for equalizing input data, again adjustment circuit 109 for adjusting the gain of the input data, an A/D circuit 110 for converting analog data to digital data, atiming circuit 111 for reproducing clocks, a gainadjustment control circuit 112 for controlling thegain adjustment circuit 109, amodulation turbo decoder 113 for turbo-decoding the input data and an error correctionsoft decoder 104 for error correction soft decoding the input data. - Similarly to the
readout head 57 of the magnetic recording and/or reproducingapparatus 50, areadout head 107 reads out the readout magnetization signal D108 from therecording medium 70 to generate a readout current signal D109 conforming to the readout magnetization signal D108. Thereadout head 107 sends the so-generated current signal D109 to thedownstream side equalizer 108. - Similarly to the
equalizer 58 of the magnetic recording and/or reproducingapparatus 50, theequalizer 108 equalizes the readout current signal D109, supplied from thereadout head 107, so that the channel response from the data writing on therecording medium 70 in the recording system up to the outputting at theequalizer 108 will be of pre-set characteristics, to generate an equalized signal D110. Theequalizer 108 routes the generated equalized signal D110 to the downstream sidegain adjustment circuit 109. - Similarly to the
gain adjustment circuit 59 0f the magnetic recording and/or reproducingapparatus 50, thegain adjustment circuit 109 adjusts the gain of the equalized signal D110 supplied from theequalizer 108, based on a gain adjustment control signal D114, supplied from the gainadjustment control circuit 112, to generate a gain adjustment signal D111. Thegain adjustment circuit 109 routes the generated gain adjustment signal D111 to the downstream side A/D converter 110. - Similarly to the A/
D converter 60 of the magnetic recording and/or reproducingapparatus 50, the A/D converter 110 samples and digitizes the gain adjustment signal D111, supplied from thegain adjustment circuit 109, based on the clock signal D113, supplied from thetiming regenerating circuit 111, to generate a digital channel signal D112. The A/D converter 110 sends the generated digital channel signal D112 to thetiming regenerating circuit 111, gainadjustment control circuit 112 and to the channel andmodulation turbo decoder 113. - Similarly to the
timing generating circuit 61 of the magnetic recording and/or reproducingapparatus 50, thetiming regenerating circuit 111 regenerates clocks from the digital channel signal D112 supplied from the A/D converter 110 to generate clock signals D113. Thetiming regenerating circuit 111 sends the generated clock signals D113 to the A/D converter 110. - Similarly to the gain
adjustment control circuit 62 of the magnetic recording and/or reproducingapparatus 50, the gainadjustment control circuit 112 generates, based on the digital channel signal D112, supplied from the A/D converter 110, a gain adjustment control signal D114, which is a control signal used for maintaining the amplitude of the equalized signal D110 at an expected value. The gainadjustment control circuit 112 sends the generated gain adjustment control signal D114 to thegain adjustment circuit 109. - Similarly to the channel and
modulation turbo decoder 63 of the magnetic recording and/or reproducingapparatus 50, the channel andmodulation turbo decoder 113, is comprised of concatenated SISO decoders to effect turbo decoding. The channel andmodulation turbo decoder 113 turbo-decodes the input digital channel signal D112 from the A/D converter 110 to route the generated turbo decoded signal D115 to the downstream sideerror correction decoder 114. - Similarly to the error correction
soft decoder 54 of the magnetic recording and/or reproducingapparatus 50, the error correctionsoft decoder 114, as error correcting soft decoding means, soft-decoded the turbo decoded signal D115 supplied from themodulation SISO decoder 113 for errors based on the BCJR algorithm or SOVA to output soft or hard output data D116 to outside. - Referring to FIG. 16, the channel and
modulation turbo decoder 113 is explained in detail. - In this figure, the channel and
modulation turbo decoder 113 includes achannel SISO decoder 121, as an SISO decoder for decoding the channel response from the pre-stage of theprecoder 104 in the recording system to the outputting in theequalizer 108, adeinterleaver 123 for restoring the sequence of the input data, anSISO decoder 124, as a SISO decoder for modulation decoding the input data, aninterleaver 126 for re-arraying the sequence of the input data, achangeover switch 127 for changing over input data input as the priori probability information for information bits and twodifference taking units - The
channel SISO decoder 121, as channel decoding means, is fed with the digital channel signal D112, as a soft input supplied from the A/D converter 110, and with priori probability information D128, as selected by thechangeover switch 127 from the priori probability information D126 for information bits supplied as soft input from the A/D converter 110 and the priori probability information D127 for information bits having a value of “0”, to effect soft output decoding, based on the BCJR algorithm or SOVA, in accordance with the trellis for the channel response from the parentage of theprecoder 104 in the recording system to an output in theequalizer 108 in the reproducing system. If the interleaved data D104 prior to precoding by theprecoder 104 is expressed as C(t) (0≦t≦N), thechannel SISO decoder 121 calculates the log posterior probability ratio log (P(C(t)=1)/P(C(t)=0)), as the posterior probability information for this C(t), to send this log posterior probability ratio as the channel decoded signal D121 to the downstream sidedifference taking unit 122. - The
difference taking unit 122 finds a difference between the channel decoded signal D121, as soft input, supplied from thechannel SISO decoder 121, and the priori probability information D126, as soft input, supplied from theinterleaver 126, to output data corresponding to this difference value as soft output to thedownstream side deinterleaver 123 as the channel extrinsic information signals D122 for an information bit as found by the code constraint condition. Meanwhile, the channel extrinsic information signals D122 corresponds to the interleaved data D104 obtained on interleaving by theinterleaver 103 in the recording system. - The
deinterleaver 123, as deinterleaving means, deinterleaves the bit sequence of the interleaved data D104 from theinterleaver 103 of the recording system to the channel extrinsic information signals D122 supplied from thedifference taking unit 122 in order to restore the bit sequence to that of the original modulated encoded data D103. Thedeinterleaver 123 sends the deinterleaved data to themodulation SISO decoder 124 and to thedifference taking unit 122 as the deinterleaved signal D123 which is the priori probability information for the code bits in themodulation SISO decoder 124. - The
modulation SISO decoder 124, as modulation decoding means, decodes signals encoded by themodulation encoder 102 in the recording system, and is an SISO type modulation decoder. The modulation encoded data D103, obtained on modulation encoding by themodulation encoder 102 with a code rate R=K/N, is specified as M(t) (0≦t<N) and the error correction encoded data D102 prior to modulation encoding by themodulation encoder 102 is specified as E(t) (0≦t<K). Themodulation SISO decoder 124 is fed with the deinterleaved signal D123, supplied as soft input from thedeinterleaver 123, and calculates the log posterior probability ratio log (P(M(t)=1)/P(M(t)=0)), as posterior probability information for M(t), using the trellis corresponding to the constraint condition, to send the so-calculated log posterior probability ratio as the modulation channel decoded signal D124 to thedifference taking unit 125. Themodulation SISO decoder 124 also calculates the log posterior probability ratio log (P(E(t)=1)/P(E(t)=0)), as posterior probability information for E(t), to send the so-calculated log posterior probability ratio as the turbo decoded signal D115 to the error correctionsoft decoder 114. - The
difference taking unit 125 finds a difference between the modulation channel decoded signal D124, supplied as soft input from themodulation SISO decoder 124, and the deinterleaved signal D123, supplied as soft input from thedeinterleaver 123, to output the data as the difference value as soft output to thedownstream side interleaver 126 as the modulated extrinsic information signals D125, which is the extrinsic information for a code bit as found by the code constraint condition. - The
interleaver 126, as second interleaving means, interleaves the modulated extrinsic information signals D125, supplied from thedifference taking unit 125, based on the same interleaving position information as that of theinterleaver 103 of the recording system. Theinterleaver 126 sends the interleaved data to thechannel SISO decoder 121 and to thedifference taking unit 122 as being the priori probability information signal D126 for the information bit in thechannel SISO decoder 121. - In the initial stage of the decoding, the
changeover switch 127 is set to the fixed terminal c supplying avalue 0 corresponding to the priori probability information signal D127 to select the priori probability information signal D127 as being the priori probability information signal D128 for an information bit in thechannel SISO decoder 121. Thechangeover switch 127 then is set to a fixed terminal d supplying the priori probability information signal D126 supplied from theinterleaver 126 to select the priori probability information signal D126 as being the priori probability information signal D128. - Similarly to the channel and
modulation turbo decoder 63 in the previously described magnetic recording and/or reproducing apparatus, the channel andmodulation turbo decoder 113, is provided with themodulation SISO decoder 124 and thechannel SISO decoder 121, as counterparts to themodulation coder 102 and theprecoder 104 of the recording system, respectively, as described above, to decompose the code of high decoding complexity into elements with lower decoding complexity, such as to sequentially improve characteristics by the interaction between thechannel SISO decoder 121 and themodulation SISO decoder 124. If fed with the digital channel signal D112, as a soft input, from the A/D converter 110, the channel andmodulation turbo decoder 113 iterates the decoding operations from thechannel SISO decoder 121 to the modulation SISO decoder 124 a pre-set number of times, such as several to tens of times, to route the soft-output log posterior probability ratio, obtained on decoding a pre-set number of times, as the turbo decoded signal D115 to the post-stage error correctingsoft decoder 64. - In reproducing data recorded on the
recording medium 70, the reproducing system of the magnetic recording and/or reproducingapparatus 50 turbo-decodes the soft-input digital channel signal D112, generated through thereadout head 107,equalizer 108,gain adjustment circuit 109 and the A/D converter 110, by the channel andmodulation turbo decoder 113, to generate the turbo decoded signal D115 corresponding to the error correction coded data D102 input to themodulation coder 102 in the recording system. - This reproducing system soft-decodes error correction codes of the turbo decoded signal D115, generated by the channel and
modulation turbo decoder 113, by the error correctingsoft decoder 114, to output data as resulting soft output directly to outside as output data D116, or binary-codes the soft-output data to generate hard-output data D116 which is issued to outside. - The reproducing system of the magnetic recording and/or reproducing
apparatus 100 is provided in this manner with the channel andmodulation turbo decoder 113 and performs turbo decoding between themodulation SISO decoder 124 and thechannel SISO decoder 121 corresponding to themodulation coder 102 and theprecoder 104 of the recording system to realize decoding in meeting with the channel response and the modulation encoding. - The magnetic recording and/or reproducing
apparatus 100 includes, in its recording system, theinterleaver 103 downstream of t themodulation encoder 102, to effect encoding by serial concatenated code between themodulation encoder 102 and theprecoder 104, while including, on its reproducing side, the channel andmodulation turbo decoder 113 to effect turbo decoding to realize high performance coding as well as highly efficient turbo decoding exploiting the soft information for the entire decoding processing for the code. Since there is no necessity of diminishing the information, the decoding error rate can be lowered significantly. Moreover, the magnetic recording and/or reproducingapparatus 100 effects coding in the recording system, as correlation is afforded to the fore and aft side data. In addition, trellis decoding can be performed on the reproducing side in meeting with the constraint condition, thus further lowering the decoding error rate. - The above-described magnetic recording and/or reproducing
apparatus apparatus 100, encoding can be made as correlation is afforded to the fore and aft side data, without doing block-based encoding or decoding, while trellis decoding can be made in meeting with the constraint conditions, thus further lowering the decoding error rate. That is, the magnetic recording and/or reproducingapparatus - The present invention is not limited to the above-described embodiment. For example, the present invention may be applied to a
recording medium 70 other than the recording medium of the magnetic recording system, that is to a recording medium by the optical recording system, such as a so-called CD (Compact Disc) or to the DVD (Digital Versatile Disc) or to a recording medium of the photomagnetic recording system, such as a so-called magneto-optical disc (MO) disc. - In the above-described embodiment, it is assumed that the magnetic recording and/or reproducing
apparatus 100 performs trellis modulation encoding on the encoder side and trellis modulation decoding on the decoder side. However, the present invention is applicable to such a case wherein the trellis modulation decoding is performed on the decoder side to output a soft decision value even in case the trellis modulation encoding is not performed on the encoding side, as when block modulation is effected on the encoder side. - Moreover, in the above-described embodiment, it is assumed that the magnetic recording and/or reproducing
apparatus - In the foregoing, the present invention has been disclosed only by way of illustration and should not be interpreted in a limiting fashion. The scope of the present invention is to be interpreted in light of the description of the following claims.
Claims (21)
1. A data recording apparatus for recording data on a recording medium, comprising:
modulation encoding means for applying predetermined modulation encoding to input data;
interleaving means for interleaving data supplied from said modulation encoding means for re-arraying the data sequence; and
precoding means for filtering data supplied from said interleaving means to compensate for channel characteristics.
2. (canceled)
3. The data recording apparatus according to claim 1 further comprising:
error correction coding means for applying error correction coding to the input data;
said modulation encoding means modulation encoding the data supplied from said error correction coding means.
4. The data recording apparatus according to claim 1 wherein said modulation encoding means encodes input data in accordance with a constraint condition.
5. The data recording apparatus according to claim 4 wherein said interleaving means interleaves data encoded by said modulation encoding means so that said constraint condition is satisfied.
6. The data recording apparatus according to claim 4 wherein said modulation encoding means encodes the input data by block modulation.
7. The data recording apparatus according to claim 6 wherein said interleaving means interleaves data encoded by said modulation encoding means in terms of a modulation encoding block as a unit.
8. The data recording apparatus according to claim 4 wherein said modulation encoding means encodes input data in accordance with a trellis conforming to said constraint condition.
9. The data recording apparatus according to claim 8 wherein said interleaving means interleaves data encoded by said modulation encoding means in terms of a modulation encoding block of said trellis as a unit.
10. The data recording apparatus according to claim 1 wherein data is recorded on said recording medium in a magnetic, optical or magneto-optical system.
11. A data recording method for recording data on a recording medium, comprising the steps of:
applying predetermined modulation encoding to input data;
interleaving the modulation-encoded data supplied from said modulation encoding step for re-arraying the data sequence; and
filtering the interleaved modulation-encoded data to compensate for channel characteristics.
12. (canceled)
13. The data recording method according to claim 11 wherein said input data is error correction coded data.
14. The data recording method according to claim 11 wherein said step of applying encodes input data in accordance with a constraint condition.
15. The data recording method according to claim 14 wherein said step of interleaving interleaves the modulation-encoded data so that said constraint condition is satisfied.
16. The data recording method according to claim 14 wherein said step of applying encodes the input data by block modulation.
17. The data recording method according to claim 16 wherein said step of interleaving the modulation-encoded data in terms of a modulation encoding block as a unit.
18. The data recording method according to claim 14 wherein said step of applying encodes input data in accordance with a trellis conforming to said constraint condition.
19. The data recording method according to claim 18 wherein said step of interleaving interleaves the modulation-encoded data in terms of a modulation encoding block of said trellis as a unit.
20. The data recording method according to claim 11 wherein data is recorded on said recording medium in a magnetic, optical or magneto-optical system.
21-88. (Canceled)
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20130101051A1 (en) * | 2010-06-25 | 2013-04-25 | Thomson Licensing | Priori training in a mobile dtv system |
Families Citing this family (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2002076925A (en) * | 2000-08-31 | 2002-03-15 | Sony Corp | Apparatus and method for soft-output decoding and apparatus and method for decoding |
US7234096B2 (en) | 2001-04-18 | 2007-06-19 | Sharp Kabushiki Kaisha | Decoding method and recording-medium reproducing apparatus |
US6996764B2 (en) | 2001-04-18 | 2006-02-07 | Sharp Kabushiki Kaisha | Coding method, recording medium, decoding method, and recording-medium reproducing apparatus |
JP4185314B2 (en) * | 2002-06-07 | 2008-11-26 | 富士通株式会社 | Information recording / reproducing apparatus, optical disc apparatus, and data reproducing method |
CN1701517B (en) | 2003-08-28 | 2010-11-24 | 索尼株式会社 | Decoding device and method |
KR100559730B1 (en) * | 2003-09-22 | 2006-03-15 | 삼성전자주식회사 | Encoding/decoding methods and apparatuses for recording system |
US7395482B2 (en) * | 2003-12-18 | 2008-07-01 | International Business Machines Corporation | Data storage systems |
US7386780B2 (en) * | 2005-02-03 | 2008-06-10 | Agere Systems Inc. | Method and apparatus for encoding and precoding digital data within modulation code constraints |
TWI360126B (en) * | 2006-09-28 | 2012-03-11 | Sandisk Corp | Nonvolatile memory with adaptive operations and me |
US7848465B2 (en) * | 2007-04-02 | 2010-12-07 | Broadcom Corporation | Joint decoding of ISI (inter-symbol interference) channel and modulation codes |
US8276038B2 (en) | 2007-08-03 | 2012-09-25 | International Business Machines Corporation | Data storage systems |
CA2660073A1 (en) * | 2008-03-25 | 2009-09-25 | Kenneth Gracie | Event cleanup processing for improving the performance of sequence based decoders |
Citations (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5060221A (en) * | 1988-05-16 | 1991-10-22 | Sony Corporation | Digital data recording/reproduction apparatus |
US5263051A (en) * | 1991-07-05 | 1993-11-16 | Codex Corporation | Device and method of interleaving for a trellis precoding system |
US5438369A (en) * | 1992-08-17 | 1995-08-01 | Zenith Electronics Corporation | Digital data interleaving system with improved error correctability for vertically correlated interference |
US5635933A (en) * | 1995-06-30 | 1997-06-03 | Quantum Corporation | Rate 16/17 (d=0,G=6/I=7) modulation code for a magnetic recording channel |
US5732088A (en) * | 1995-05-31 | 1998-03-24 | Sony Corporation | Data recording/reproducing apparatus, method thereof, and data record medium |
US6141384A (en) * | 1997-02-14 | 2000-10-31 | Philips Electronics North America Corporation | Decoder for trellis encoded interleaved data stream and HDTV receiver including such a decoder |
US6233598B1 (en) * | 1998-09-11 | 2001-05-15 | International Business Machines Corporation | Interleaved finite impulse response (FIR) filter functions for servo and data detection in a direct access storage device (DASD) |
US6356555B1 (en) * | 1995-08-25 | 2002-03-12 | Terayon Communications Systems, Inc. | Apparatus and method for digital data transmission using orthogonal codes |
US6366418B1 (en) * | 1999-06-30 | 2002-04-02 | Maxtor Corporation | Method for reducing data overhead in PRML data channel |
US6405342B1 (en) * | 1999-09-10 | 2002-06-11 | Western Digital Technologies, Inc. | Disk drive employing a multiple-input sequence detector responsive to reliability metrics to improve a retry operation |
US6546518B1 (en) * | 1999-05-19 | 2003-04-08 | Texas Instruments Incorporated | Detector error suppression circuit and method |
US6694477B1 (en) * | 2000-09-28 | 2004-02-17 | Western Digital Technologies, Inc. | Communication channel employing an ECC decoder enhanced by likely error events of a trellis sequence detector |
US6826722B2 (en) * | 2000-03-23 | 2004-11-30 | Sony Corporation | Method and apparatus for reproducing data and method and apparatus for recording and/or reproducing data |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100200801B1 (en) * | 1991-08-31 | 1999-06-15 | 윤종용 | Error correction device |
US5392299A (en) * | 1992-01-15 | 1995-02-21 | E-Systems, Inc. | Triple orthogonally interleaed error correction system |
US5241563A (en) * | 1992-08-10 | 1993-08-31 | General Instrument Corporation | Method and apparatus for communicating interleaved data |
KR100189906B1 (en) * | 1996-04-17 | 1999-06-01 | 윤종용 | Viterbi decoding method and circuit |
EP0998087A1 (en) * | 1998-10-30 | 2000-05-03 | Lucent Technologies Inc. | Multilevel transmission system and method with adaptive mapping |
-
2000
- 2000-03-23 JP JP2000087127A patent/JP2001266499A/en not_active Abandoned
-
2001
- 2001-03-21 US US09/814,379 patent/US7196999B2/en not_active Expired - Fee Related
- 2001-03-21 EP EP01302599A patent/EP1143440A3/en not_active Withdrawn
-
2004
- 2004-07-22 US US10/898,043 patent/US20040260999A1/en not_active Abandoned
Patent Citations (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5060221A (en) * | 1988-05-16 | 1991-10-22 | Sony Corporation | Digital data recording/reproduction apparatus |
US5263051A (en) * | 1991-07-05 | 1993-11-16 | Codex Corporation | Device and method of interleaving for a trellis precoding system |
US5438369A (en) * | 1992-08-17 | 1995-08-01 | Zenith Electronics Corporation | Digital data interleaving system with improved error correctability for vertically correlated interference |
US5732088A (en) * | 1995-05-31 | 1998-03-24 | Sony Corporation | Data recording/reproducing apparatus, method thereof, and data record medium |
US5635933A (en) * | 1995-06-30 | 1997-06-03 | Quantum Corporation | Rate 16/17 (d=0,G=6/I=7) modulation code for a magnetic recording channel |
US6356555B1 (en) * | 1995-08-25 | 2002-03-12 | Terayon Communications Systems, Inc. | Apparatus and method for digital data transmission using orthogonal codes |
US6141384A (en) * | 1997-02-14 | 2000-10-31 | Philips Electronics North America Corporation | Decoder for trellis encoded interleaved data stream and HDTV receiver including such a decoder |
US6233598B1 (en) * | 1998-09-11 | 2001-05-15 | International Business Machines Corporation | Interleaved finite impulse response (FIR) filter functions for servo and data detection in a direct access storage device (DASD) |
US6546518B1 (en) * | 1999-05-19 | 2003-04-08 | Texas Instruments Incorporated | Detector error suppression circuit and method |
US6366418B1 (en) * | 1999-06-30 | 2002-04-02 | Maxtor Corporation | Method for reducing data overhead in PRML data channel |
US6405342B1 (en) * | 1999-09-10 | 2002-06-11 | Western Digital Technologies, Inc. | Disk drive employing a multiple-input sequence detector responsive to reliability metrics to improve a retry operation |
US6826722B2 (en) * | 2000-03-23 | 2004-11-30 | Sony Corporation | Method and apparatus for reproducing data and method and apparatus for recording and/or reproducing data |
US6694477B1 (en) * | 2000-09-28 | 2004-02-17 | Western Digital Technologies, Inc. | Communication channel employing an ECC decoder enhanced by likely error events of a trellis sequence detector |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20130101051A1 (en) * | 2010-06-25 | 2013-04-25 | Thomson Licensing | Priori training in a mobile dtv system |
US8995582B2 (en) * | 2010-06-25 | 2015-03-31 | Thomson Licensing | Priori training in a mobile DTV system |
Also Published As
Publication number | Publication date |
---|---|
JP2001266499A (en) | 2001-09-28 |
US7196999B2 (en) | 2007-03-27 |
EP1143440A3 (en) | 2005-01-05 |
EP1143440A2 (en) | 2001-10-10 |
US20020057640A1 (en) | 2002-05-16 |
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