CA1091298A - System for transmission of information - Google Patents
System for transmission of informationInfo
- Publication number
- CA1091298A CA1091298A CA238,232A CA238232A CA1091298A CA 1091298 A CA1091298 A CA 1091298A CA 238232 A CA238232 A CA 238232A CA 1091298 A CA1091298 A CA 1091298A
- Authority
- CA
- Canada
- Prior art keywords
- generator
- frequency
- output
- converter
- clock generator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
- H04K3/00—Jamming of communication; Counter-measures
- H04K3/20—Countermeasures against jamming
- H04K3/25—Countermeasures against jamming based on characteristics of target signal or of transmission, e.g. using direct sequence spread spectrum or fast frequency hopping
Abstract
Abstract of the Disclosure The invention relates to information transmission systems in which the band is spread at the transmitting end by means of a pseudo-noise sequence and is returned to normal at the receiving end by a similar sequence.
In such systems it is essential that the frequency of the various oscillators used for the frequency conversions should be kept constant, or alternatively that the oscillators at the receiving end should be synchronised with the oscillators at the transmitting end. In accordance with the present invention the oscillators at the transmitting end are synchronised by the clock fre-quency of the code generator and at the receiving end this clock frequency is extracted from the received signal and used to synchronise the oscillators in the various conversions. One of the oscillators at the receiving end may be a Gunn oscillator which is synchronised by applying the output of the pulse generator to its synchronising input terminal through a frequency multiplier.
In another arrangement the frequency of the Gunn oscillator is controlled by comparing the phase of the output with the phase of the output of a frequency multiplier supplied by the pulse generator. In yet another arrangement the outputs of the Gunn oscillator and the frequency multiplier are mixed to form a difference signal which is compared in phase with the outputs of a low frequency reference oscillator.
In such systems it is essential that the frequency of the various oscillators used for the frequency conversions should be kept constant, or alternatively that the oscillators at the receiving end should be synchronised with the oscillators at the transmitting end. In accordance with the present invention the oscillators at the transmitting end are synchronised by the clock fre-quency of the code generator and at the receiving end this clock frequency is extracted from the received signal and used to synchronise the oscillators in the various conversions. One of the oscillators at the receiving end may be a Gunn oscillator which is synchronised by applying the output of the pulse generator to its synchronising input terminal through a frequency multiplier.
In another arrangement the frequency of the Gunn oscillator is controlled by comparing the phase of the output with the phase of the output of a frequency multiplier supplied by the pulse generator. In yet another arrangement the outputs of the Gunn oscillator and the frequency multiplier are mixed to form a difference signal which is compared in phase with the outputs of a low frequency reference oscillator.
Description
1 0~3 i~
Tllis invention relates to an arrangemen~ for information trans-mission, in which at the transmitting end a band spread is effected by means of a pseudo-noise sequence, and at the receiving end this band spread is cancelled by means of an identical pseudo-noise sequence prior to the actual demodulation.
Information transmitting systems of this type possess a transmis-sion band width which is very much greater than the band width required for the transmission of the signal. In these systems the signal is transmitted as if it were "blurred" over a wide frequency spectrum. This band spread can be effected in different ways. The best known method consists in that the phase of the signal which has been modulated onto a carrier is switched over at the transmitting end with the aid of a high-bit-frequency pseudo-noise - sequence produced by a code generator. Another possibility consists in using such a pseudo-noise sequence to switch over the frequency of the converter generator for the upwards mixer which converts the signal which is to be trans-mitted into the radio-frequency state.
The advantages of a band spread of this type can on the one hand consist in the fact that the same frequency band may be used simultaneously for a plurality of information connections in that the pairs of transmitter/
receivers employ different pseudo-noise sequences which exhibit good cross-`~ correlation properties, i.e. that the maximum values of the cross-correlation functions are low in comparison to the maximum values of the auto-correlation ` functions of the individual pseudo-noise sequences. On the other hand, the band spread has the advantage that it is extremely insensitive to electro-magnetic interference sources. This is due to the fact that an interference source which may fall into the frequency band to be transmitted, and which can possess a large amplitude in comparison to the spectral amplitude of the signal, is itself spread in terms of energy over a wide frequency band during the cancellation of the band spread which must be effected at the receiving end, whereas the energy of the signal is drawn into a narroN frequency band.
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Thus an informatian transmission system of this type is especially suitable for military uses in which the dis~dvantage of the high band width require-ment cannot be afforded any significance in view of the advantage of a high resistance to interference.
In the design of an information transmission arrangement operat-ing with a band spread, the long-term stability of the converter generators tc be provided at the transmitting end and at the receiving end is of parti-cular importance. In the event of stringent demands on the resistance to interference sources, narrow band filters must be employed at the receiving end both in the correlation network which is required to cancel the band spread and also before the actual demodulator. These narrow band filters necessitate extreme stability of the converter oscillators, because the mini-- mum band width of these band filters must be selected to be at least such that the signal can be received satisfactorily taking into account the possible frequency drift of the converter oscillators.
As shown in practice, the long term stability of, for example, a thermally processed fifth harmonic quartz crystal exhibits a mean value of 7-8-10 6 within a period of five years. The likely frequency change in the temperature range from -20C to +70C amounts to approximately + 15 10 6.
If quartz oscillators of this type are used as a basis for multiplier chains, the maximum frequency deviation which may be expected at a nominal frequency of 14 GHz, for example, is in fact + 322 kHz. Even when the quartz oscilla-tors exhibit very good temperature stability during use, it is hardly possible to achieve a frequency fluctuation of less than approximately + 110 kHz over a period of five years. On the other hand if a high resistance to inter-` ference is to be achieved in such a system, the requisite long-term stability is in the order of + 20 kHz. Thus it is not possible to employ a frequency multiplication of the described type to construct a converter oscillator of ' this kind. Even when Gunn oscillators are used, long-term stabilities of the above-stated order can be achieved only with a very large outlay. The drift ' : - .
~ "'r ~., ': . :, lO~
of approx. 20 kHz/C occurring in the case of a Gunn oscillator indicated the requisite outlay for temperature stabilisation. In the event of long storage it would also be necessary to carry out a recalibration shortly before use.
The aim of the invention isJ for an information transmission arrangement of the type described in ~he introduction, to provide a realisa-tion in which, whilst ensuring the requisite low band width of the afore-mentioned receiving-end band filters, which is necessary in order to achieve the desired resistance to interference, it is possible to employ converter oscillators whose long-term stability is subject to considerably less strin-gent requirements than, as described in the introduction/ would otherwise be necessary.
Commencing from an information transmission arrangement in which a band spread is effected at the transmitting end by means of a pseudo-noise-sequence and in which at the receiving end this band spread is cancelled by means of an identical pseudo-noise-sequence prior to the actual demodulation, this aim is realised in accordance with the invention in that at the transmit-:
ting end at least the converter generator for the upwards mixer is synchronisedby the clock frequency of the code generator which produces the pseudo-noise-sequence, and at the receiving end at least the converter generator for the downwards mixer is synchronised by the clock frequency of the code generator which produces the identical pseudo-noise-sequence, and that at the receiving end this clock frequency is derived from the input signal by means of a synchronising circuit.
The invention is based upon the essential recognition that the outlay, in itself very high, for the receiving-end synchronisation of the pseudo-noise-generator which is required to cancel the band spread and which `
is identical to th~t at the transmitting end, provides the possibility of achieving a synchronisation, which satisfies the most stringent requirements, in respect of all the converter generators provided at the transmitting end and at the receiving end via the relevant clock generator, if the synchronisa-, .
~ - 3 -:-: A
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tion of the receiving-end clock generator is additionally derived from the signal incoming at the receiving end.
Thus, in accordance with the invention there is pro- ~
- vided an arrangement for information transmission in which a transmitting end is supplied with an upwards mixer and with a first converter generator for the purpose of producing a trans-mitting signal, a band spread being effected by means of a pseudo-noise-sequence and in which a receiving end is supplied with a downwards mixer and with a second converter generator for the purpose of producing an if-signal, said band spread being cancelled by means of an identical pseudo-noise-sequence prior to actual demodulation, wherein at the transmitting end at least the converter generator for the upwards mixer is synchronised by ....
a clock frequency produced by a first clock generator of a code generator which produces the pseudo-noise-sequence, and at the receiving end at least said second converter generator, for the downwards mixer, is synchronised by a clock frequency produced -~ by a controllable second clock generator of the code generator ; which produces the identical pseudo-noise-sequence as at the ; 20 transmitting end, and wherein at the receiving end the second -> clock generator is controlled from an input signal by means of a synchronising circuit.
; In a first preferred embodiment, at the transmitting end and/or at the receiving end, the said one converter generator is in the form of a frequency multiplier which is `::
connected at its input to the clock generator which serves to , :.
~ produce the clock frequency.
-In a second preferred embodiment, at the transmitting end and/or at the receiving end the said one converter generator is in the form of an injection-synchronised Gunn oscillator ~ .
whose synchronising input is supplied with the output of the . .
.~ clock generator via a frequency multiplier.
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In a third preferred embodiment, at the transmitting end and/or at the receiving end, the said one converter genera tor is a Gunn oscillator which may be controlled in respect of its frequency and whose control signal is obtained from the phase comparison of the Gunn oscillator output and the output of a frequency multiplier which is fed at its input by the clock generator.
In a fourth preferred embodiment, at the transmitting ` end and/or at the receiving end, the said one converter genera- -tor is likewise a Gunn . , .
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oscillator which may be controlled in its frequency and in which, in a mixer, a difference signal is obtained from the Gunn oscillator output and the output of a frequency multiplier which is fed at its input by the clock generator, which difference signal is applied with the output of a low-frequency reference oscillator to the two inputs of a phase comparator, and wherein the control signal for the Gunn oscillator is derived from this phase comparator.
The receiving-end synchronising circuit is in known manner a delay locked loop, which synchronises the clock generator in dependence upon the agreement between the pseudo-noise sequence contained in the input signal and the identical sequence produced by the receiving-end pseudo-noise-generator.
In the arrangement in accordance with the invention, the fact that the fundamental pulse generator for the pseudo-noise-generator is coupled to at least one converter generator at the receiving end, means that in the execution of a first synchronisation or resynchronisation following a loss of synchronisationJ it is not possible to achieve a high-speed acquisition.
In other words for an acquisition the clock generator can only be adjusted by a very small degree in comparison to its theoretical frequency. In practice this means that the execution of such a first-synchonisation or resynchronisa-tion occupies a period of time in the order of one second or several seconds, depending upon the pèriod length of the pseudo-noise sequence being used. If this period of time is too long with regard to the special application of the - subject of the invention, then it is necessary to provide special measures facilitating a high-speed acquisition of the clock generator. These measures can simply consist in providing that at the receiving end the said one con-verter generator can be connected via a change-over switch selectively to the clock genera~or or to another auxiliary oscillator tuned to the theoretical frequency of the clock generator.
When the subject of the invention is used for the transmission of items of information from a mobile stationJ such as a flying objectJ to a A
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receiving station, in particular another flying object, the relative movement between transmitting station and receiving station produces a so-called Doppler shift of the frequency of the received signal in relation to the fre-~ quency of the transmitter. This Doppler effect is practically compensated by :i the synchronisation provided by ~he present invention.
The invention is to be explained in further detail in the follow-ing making reference to exemplary embodiments represented in the drawing, :~ in which:-Figuresl and 2 indicate a first embodiment of a transmitter and 10 of a receiver in accordance with the invention, Figures3 and 4 illustr.ate a second embodiment of a transmitter and a receiver in accordance with the invention, Figure 5 is a first embodiment of a converter generator corres-ponding to the arrangemonts shown in Figures 1 to 4, Figure 6 is a second embodiment of a converter generator corres-.~ ponding to the arrangements shown in Figures 1 to 4, Figure 7 illustrates a third embodiment of a converter generator . corresponding to the arrangements shown in Figures 1 to 4, and - Figure 8 is a fourth embodiment of a converter generator corres-ponding to the arrangements shown in Figures 1 to 4.
In the block circuit diagram, represented in Figure 1, of the . transmitting end of an arrangement for information transmission in accordance `~ with the invention, in the modulator MO the signal supplied b~ the signal . source Si is modulated onto the carrier supplied by the converter generator .. UGl, and is then switched over in phase in the biphase modulator PU in ~..
. dependence upun the pseudo-noise-pulse-sequence supplied by the pseudo-noise-:: , :- generator PG. The signal, whose band width has thus been spread out, is .~; translated to the radio-frequency state in the upwards mixer M2, is amplified ; in the subsequently connected travelling wave amplifier WV, and is emitted '- 30 via the transmitter antenna SA. The upwards mixer M2 obtains the carrier ~ A - 6 -' ::
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from the converter generator UG2. The pseudo-noise-generator PC and the converter generators UGl and UG2 are each connected by one input to the output of the clock generator TG which primarily supplies the clock frequency for the pseudo-noise-generator PG but at the same time also synchronises the converter generators UGl and UG2 in accordance with the invention.
The signal received via the receiving antenna EA of the receiver illustrated in Figure 2 is firstly transformed into an intermediate frequency level in the downwards mixer M3 which obtains the carrier from the converter generator UG3, and in this level is freed of the pseudo-noise-pulse-sequence superimposed at the transmitting end, in a biphase modulator PR. This is again effected with the aid of a pseudo-noise-generator PG arranged at the receiving end which is identical to the pseudo-noise generator at the trans-mitting end, and which, as will be explained in detail in the following, is synchronised to the pseudo-noise-sequence contained in the incoming signal.
The signal, which in this way has been freed of the transmitting-end band spread is then conducted to an intermediate frequency filter ZF which is match-ed to the band width of said signal and which is in the form of a band-pass filter which is adjoined by the actual demodulator D.
., As at the transmitting end~ the receiving-end pseudo-noise-`~ 20 generator PG is connected to the output of a fundamental pulse generator TG
whose output signal simultaneously synchronises the converter generator UG3 via the change-over switch. The synchronisation o the clock generator TG is effected via the synchronising circuit SS which here consists o a delay locked loop such as known for example through the publication "IEEE Transactions on C = unication Technology" Vol. COM-15, No. 1, Feb. 1967, p. 69 to 78, in particular page 70, Figure 1 and associated description (delay locked loop).
By way of comparison signal, the synchronising circuit SS obtains the output signal of the pseudo-noise-generator PG and the output signal of the downwards mixer M3. The change-over switch S indicates operation in the ; 30 synchronous state in the switching position shown in the Figure. On the .,.
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execution of a first synchronisation or a resynchronisation, the change-over switch S is brought, via tlle synchronising circuit SS into the second switch-ing position in which the converter generator UG3 is connected to the auxiliary oscillator IIO. The auxiliary oscillator H0 is tuned to the theoretical frequency of the clock generator. This facilitates a high-speed acquisition, in which the frequency of the clock generator TG is changed in a given direc-tion, via the synchronising circuit SS, so that the two pseudo-noise-sequences which are to be compared with one another move past one another facilitating a rapid discovery of the synchronisation point.
The clock generator TG at the transmitting end in Figure 1, which possesses e.g. a clock frequency ft of 80 MHz can be designed for long-term frequency stability in the order of 15.10-6 ft. As the two converter generators UGl and UG2 are dependent upon the clock frequency of the clock generator in terms of their synchronisation, they exhibit a corresponding long-term frequency stability. The inconstancy of the clock generator TG is practically entirely compensated with the aid of the synchronisation of the receiving-end clock generator TG by the synchronising circuit SS. As the ; converter generator UG3 for the downwards mixer M3 is dependent upon the clock frequency of the clock generator, the signal at the output of the down-wards mixer and the signal whose band spread has been cancelled present at the input of the intermediate frequency filter ZF possess a long-term constancy which meets even extreme demands. The accuracy is now merely governed by the - degree of accuracy with which the synchronising circuit SS synchronises the - receiving-end clock generator TG in dependence upon the incoming signal. With the type of synchronising circuits employed, this means that only frequency changes occurring in periods of time which are shorter than the build-up time of the loop filter (loop band width approx. 50 Hz) of the delay locked loop are not compensated. However, possible short-term instability of this type will have virtually no influence on the information transmission, and furthermore when high quality Gunn oscillators are employed will be negligible.
:.
A
'"` 1091'~ , ~lus with the aid of the present invention it is possible for example, in order to achieve the desired high resistance to interference, to select the band width of the intermediate frequency filter ZF to be practically equal to the band width of the wanted signal at the output of the biphase modulator PR.
In the further exemplary embodiment, shown in Figures 3 and 4 of an arrangement for information transmission in accordance with the invention, in contrast to the exemplary embodiment in Figures 1 and 2, the spreading of the frequency band and the cancellation thereof at the receiving end is effected not by means of switching over the phase of the useful signal, but by switching 10 over the frequency of the converter generator of the upwards mixer. At the transmitting end in the block circuit diagram shown in Figure 3, the signal source Si again possesses the modulator M0 in which the signal is translated into an intermediate frequency position with the aid of the carrier supplied by the converter generator UGl and is then conducted to the upwards mixer M2'.
The converter generator UG2' is a generator which may be switched over in res-pect of its frequency and which is controlled via a control input ~not marked) by the pseudo-noise-pulse-sequence of the pseudo-noise-generator PG. The up-wards mixer M2' is designed to possess a very wide band and at its output is connected to the transmi.tting antenna SA. The pseudo-noise-generator PG is itself controlled by the clock frequency of the clock generator TG. The con-verter generators UGl and UG2' are also synchronised via the clock generator.
In accordance with Figure 4, the transmitted signal which is in-coming at the receiving antenna EA and which has been spread in respect of its band width is transformed in the downwards mixer M3' into the original band ,, ` width in the intermediate frequency level, by switching over the converter ~ generator UG2', similarly as at the transmitting end, by the identical pseudo-.~: noise-sequence of the receiving-end pseudo-noise-generator PG. The synchronis-;.- ing circuit SS is connected via its two inputs on the one hand to the input ~ end of the downwards mixer M3' and on the other hand to the output of the - converter generator UG2' whose freauency has been switched over. The other . 30 assemblies shown in Figure 4 are identical to the assemblies shown in Figure - A _ 9 _ .. . .
1091~
Tllis invention relates to an arrangemen~ for information trans-mission, in which at the transmitting end a band spread is effected by means of a pseudo-noise sequence, and at the receiving end this band spread is cancelled by means of an identical pseudo-noise sequence prior to the actual demodulation.
Information transmitting systems of this type possess a transmis-sion band width which is very much greater than the band width required for the transmission of the signal. In these systems the signal is transmitted as if it were "blurred" over a wide frequency spectrum. This band spread can be effected in different ways. The best known method consists in that the phase of the signal which has been modulated onto a carrier is switched over at the transmitting end with the aid of a high-bit-frequency pseudo-noise - sequence produced by a code generator. Another possibility consists in using such a pseudo-noise sequence to switch over the frequency of the converter generator for the upwards mixer which converts the signal which is to be trans-mitted into the radio-frequency state.
The advantages of a band spread of this type can on the one hand consist in the fact that the same frequency band may be used simultaneously for a plurality of information connections in that the pairs of transmitter/
receivers employ different pseudo-noise sequences which exhibit good cross-`~ correlation properties, i.e. that the maximum values of the cross-correlation functions are low in comparison to the maximum values of the auto-correlation ` functions of the individual pseudo-noise sequences. On the other hand, the band spread has the advantage that it is extremely insensitive to electro-magnetic interference sources. This is due to the fact that an interference source which may fall into the frequency band to be transmitted, and which can possess a large amplitude in comparison to the spectral amplitude of the signal, is itself spread in terms of energy over a wide frequency band during the cancellation of the band spread which must be effected at the receiving end, whereas the energy of the signal is drawn into a narroN frequency band.
~-lV'~
Thus an informatian transmission system of this type is especially suitable for military uses in which the dis~dvantage of the high band width require-ment cannot be afforded any significance in view of the advantage of a high resistance to interference.
In the design of an information transmission arrangement operat-ing with a band spread, the long-term stability of the converter generators tc be provided at the transmitting end and at the receiving end is of parti-cular importance. In the event of stringent demands on the resistance to interference sources, narrow band filters must be employed at the receiving end both in the correlation network which is required to cancel the band spread and also before the actual demodulator. These narrow band filters necessitate extreme stability of the converter oscillators, because the mini-- mum band width of these band filters must be selected to be at least such that the signal can be received satisfactorily taking into account the possible frequency drift of the converter oscillators.
As shown in practice, the long term stability of, for example, a thermally processed fifth harmonic quartz crystal exhibits a mean value of 7-8-10 6 within a period of five years. The likely frequency change in the temperature range from -20C to +70C amounts to approximately + 15 10 6.
If quartz oscillators of this type are used as a basis for multiplier chains, the maximum frequency deviation which may be expected at a nominal frequency of 14 GHz, for example, is in fact + 322 kHz. Even when the quartz oscilla-tors exhibit very good temperature stability during use, it is hardly possible to achieve a frequency fluctuation of less than approximately + 110 kHz over a period of five years. On the other hand if a high resistance to inter-` ference is to be achieved in such a system, the requisite long-term stability is in the order of + 20 kHz. Thus it is not possible to employ a frequency multiplication of the described type to construct a converter oscillator of ' this kind. Even when Gunn oscillators are used, long-term stabilities of the above-stated order can be achieved only with a very large outlay. The drift ' : - .
~ "'r ~., ': . :, lO~
of approx. 20 kHz/C occurring in the case of a Gunn oscillator indicated the requisite outlay for temperature stabilisation. In the event of long storage it would also be necessary to carry out a recalibration shortly before use.
The aim of the invention isJ for an information transmission arrangement of the type described in ~he introduction, to provide a realisa-tion in which, whilst ensuring the requisite low band width of the afore-mentioned receiving-end band filters, which is necessary in order to achieve the desired resistance to interference, it is possible to employ converter oscillators whose long-term stability is subject to considerably less strin-gent requirements than, as described in the introduction/ would otherwise be necessary.
Commencing from an information transmission arrangement in which a band spread is effected at the transmitting end by means of a pseudo-noise-sequence and in which at the receiving end this band spread is cancelled by means of an identical pseudo-noise-sequence prior to the actual demodulation, this aim is realised in accordance with the invention in that at the transmit-:
ting end at least the converter generator for the upwards mixer is synchronisedby the clock frequency of the code generator which produces the pseudo-noise-sequence, and at the receiving end at least the converter generator for the downwards mixer is synchronised by the clock frequency of the code generator which produces the identical pseudo-noise-sequence, and that at the receiving end this clock frequency is derived from the input signal by means of a synchronising circuit.
The invention is based upon the essential recognition that the outlay, in itself very high, for the receiving-end synchronisation of the pseudo-noise-generator which is required to cancel the band spread and which `
is identical to th~t at the transmitting end, provides the possibility of achieving a synchronisation, which satisfies the most stringent requirements, in respect of all the converter generators provided at the transmitting end and at the receiving end via the relevant clock generator, if the synchronisa-, .
~ - 3 -:-: A
10~1~9~
tion of the receiving-end clock generator is additionally derived from the signal incoming at the receiving end.
Thus, in accordance with the invention there is pro- ~
- vided an arrangement for information transmission in which a transmitting end is supplied with an upwards mixer and with a first converter generator for the purpose of producing a trans-mitting signal, a band spread being effected by means of a pseudo-noise-sequence and in which a receiving end is supplied with a downwards mixer and with a second converter generator for the purpose of producing an if-signal, said band spread being cancelled by means of an identical pseudo-noise-sequence prior to actual demodulation, wherein at the transmitting end at least the converter generator for the upwards mixer is synchronised by ....
a clock frequency produced by a first clock generator of a code generator which produces the pseudo-noise-sequence, and at the receiving end at least said second converter generator, for the downwards mixer, is synchronised by a clock frequency produced -~ by a controllable second clock generator of the code generator ; which produces the identical pseudo-noise-sequence as at the ; 20 transmitting end, and wherein at the receiving end the second -> clock generator is controlled from an input signal by means of a synchronising circuit.
; In a first preferred embodiment, at the transmitting end and/or at the receiving end, the said one converter generator is in the form of a frequency multiplier which is `::
connected at its input to the clock generator which serves to , :.
~ produce the clock frequency.
-In a second preferred embodiment, at the transmitting end and/or at the receiving end the said one converter generator is in the form of an injection-synchronised Gunn oscillator ~ .
whose synchronising input is supplied with the output of the . .
.~ clock generator via a frequency multiplier.
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In a third preferred embodiment, at the transmitting end and/or at the receiving end, the said one converter genera tor is a Gunn oscillator which may be controlled in respect of its frequency and whose control signal is obtained from the phase comparison of the Gunn oscillator output and the output of a frequency multiplier which is fed at its input by the clock generator.
In a fourth preferred embodiment, at the transmitting ` end and/or at the receiving end, the said one converter genera- -tor is likewise a Gunn . , .
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oscillator which may be controlled in its frequency and in which, in a mixer, a difference signal is obtained from the Gunn oscillator output and the output of a frequency multiplier which is fed at its input by the clock generator, which difference signal is applied with the output of a low-frequency reference oscillator to the two inputs of a phase comparator, and wherein the control signal for the Gunn oscillator is derived from this phase comparator.
The receiving-end synchronising circuit is in known manner a delay locked loop, which synchronises the clock generator in dependence upon the agreement between the pseudo-noise sequence contained in the input signal and the identical sequence produced by the receiving-end pseudo-noise-generator.
In the arrangement in accordance with the invention, the fact that the fundamental pulse generator for the pseudo-noise-generator is coupled to at least one converter generator at the receiving end, means that in the execution of a first synchronisation or resynchronisation following a loss of synchronisationJ it is not possible to achieve a high-speed acquisition.
In other words for an acquisition the clock generator can only be adjusted by a very small degree in comparison to its theoretical frequency. In practice this means that the execution of such a first-synchonisation or resynchronisa-tion occupies a period of time in the order of one second or several seconds, depending upon the pèriod length of the pseudo-noise sequence being used. If this period of time is too long with regard to the special application of the - subject of the invention, then it is necessary to provide special measures facilitating a high-speed acquisition of the clock generator. These measures can simply consist in providing that at the receiving end the said one con-verter generator can be connected via a change-over switch selectively to the clock genera~or or to another auxiliary oscillator tuned to the theoretical frequency of the clock generator.
When the subject of the invention is used for the transmission of items of information from a mobile stationJ such as a flying objectJ to a A
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receiving station, in particular another flying object, the relative movement between transmitting station and receiving station produces a so-called Doppler shift of the frequency of the received signal in relation to the fre-~ quency of the transmitter. This Doppler effect is practically compensated by :i the synchronisation provided by ~he present invention.
The invention is to be explained in further detail in the follow-ing making reference to exemplary embodiments represented in the drawing, :~ in which:-Figuresl and 2 indicate a first embodiment of a transmitter and 10 of a receiver in accordance with the invention, Figures3 and 4 illustr.ate a second embodiment of a transmitter and a receiver in accordance with the invention, Figure 5 is a first embodiment of a converter generator corres-ponding to the arrangemonts shown in Figures 1 to 4, Figure 6 is a second embodiment of a converter generator corres-.~ ponding to the arrangements shown in Figures 1 to 4, Figure 7 illustrates a third embodiment of a converter generator . corresponding to the arrangements shown in Figures 1 to 4, and - Figure 8 is a fourth embodiment of a converter generator corres-ponding to the arrangements shown in Figures 1 to 4.
In the block circuit diagram, represented in Figure 1, of the . transmitting end of an arrangement for information transmission in accordance `~ with the invention, in the modulator MO the signal supplied b~ the signal . source Si is modulated onto the carrier supplied by the converter generator .. UGl, and is then switched over in phase in the biphase modulator PU in ~..
. dependence upun the pseudo-noise-pulse-sequence supplied by the pseudo-noise-:: , :- generator PG. The signal, whose band width has thus been spread out, is .~; translated to the radio-frequency state in the upwards mixer M2, is amplified ; in the subsequently connected travelling wave amplifier WV, and is emitted '- 30 via the transmitter antenna SA. The upwards mixer M2 obtains the carrier ~ A - 6 -' ::
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from the converter generator UG2. The pseudo-noise-generator PC and the converter generators UGl and UG2 are each connected by one input to the output of the clock generator TG which primarily supplies the clock frequency for the pseudo-noise-generator PG but at the same time also synchronises the converter generators UGl and UG2 in accordance with the invention.
The signal received via the receiving antenna EA of the receiver illustrated in Figure 2 is firstly transformed into an intermediate frequency level in the downwards mixer M3 which obtains the carrier from the converter generator UG3, and in this level is freed of the pseudo-noise-pulse-sequence superimposed at the transmitting end, in a biphase modulator PR. This is again effected with the aid of a pseudo-noise-generator PG arranged at the receiving end which is identical to the pseudo-noise generator at the trans-mitting end, and which, as will be explained in detail in the following, is synchronised to the pseudo-noise-sequence contained in the incoming signal.
The signal, which in this way has been freed of the transmitting-end band spread is then conducted to an intermediate frequency filter ZF which is match-ed to the band width of said signal and which is in the form of a band-pass filter which is adjoined by the actual demodulator D.
., As at the transmitting end~ the receiving-end pseudo-noise-`~ 20 generator PG is connected to the output of a fundamental pulse generator TG
whose output signal simultaneously synchronises the converter generator UG3 via the change-over switch. The synchronisation o the clock generator TG is effected via the synchronising circuit SS which here consists o a delay locked loop such as known for example through the publication "IEEE Transactions on C = unication Technology" Vol. COM-15, No. 1, Feb. 1967, p. 69 to 78, in particular page 70, Figure 1 and associated description (delay locked loop).
By way of comparison signal, the synchronising circuit SS obtains the output signal of the pseudo-noise-generator PG and the output signal of the downwards mixer M3. The change-over switch S indicates operation in the ; 30 synchronous state in the switching position shown in the Figure. On the .,.
:` A - 7 -" , , : :
~V~ 9~
execution of a first synchronisation or a resynchronisation, the change-over switch S is brought, via tlle synchronising circuit SS into the second switch-ing position in which the converter generator UG3 is connected to the auxiliary oscillator IIO. The auxiliary oscillator H0 is tuned to the theoretical frequency of the clock generator. This facilitates a high-speed acquisition, in which the frequency of the clock generator TG is changed in a given direc-tion, via the synchronising circuit SS, so that the two pseudo-noise-sequences which are to be compared with one another move past one another facilitating a rapid discovery of the synchronisation point.
The clock generator TG at the transmitting end in Figure 1, which possesses e.g. a clock frequency ft of 80 MHz can be designed for long-term frequency stability in the order of 15.10-6 ft. As the two converter generators UGl and UG2 are dependent upon the clock frequency of the clock generator in terms of their synchronisation, they exhibit a corresponding long-term frequency stability. The inconstancy of the clock generator TG is practically entirely compensated with the aid of the synchronisation of the receiving-end clock generator TG by the synchronising circuit SS. As the ; converter generator UG3 for the downwards mixer M3 is dependent upon the clock frequency of the clock generator, the signal at the output of the down-wards mixer and the signal whose band spread has been cancelled present at the input of the intermediate frequency filter ZF possess a long-term constancy which meets even extreme demands. The accuracy is now merely governed by the - degree of accuracy with which the synchronising circuit SS synchronises the - receiving-end clock generator TG in dependence upon the incoming signal. With the type of synchronising circuits employed, this means that only frequency changes occurring in periods of time which are shorter than the build-up time of the loop filter (loop band width approx. 50 Hz) of the delay locked loop are not compensated. However, possible short-term instability of this type will have virtually no influence on the information transmission, and furthermore when high quality Gunn oscillators are employed will be negligible.
:.
A
'"` 1091'~ , ~lus with the aid of the present invention it is possible for example, in order to achieve the desired high resistance to interference, to select the band width of the intermediate frequency filter ZF to be practically equal to the band width of the wanted signal at the output of the biphase modulator PR.
In the further exemplary embodiment, shown in Figures 3 and 4 of an arrangement for information transmission in accordance with the invention, in contrast to the exemplary embodiment in Figures 1 and 2, the spreading of the frequency band and the cancellation thereof at the receiving end is effected not by means of switching over the phase of the useful signal, but by switching 10 over the frequency of the converter generator of the upwards mixer. At the transmitting end in the block circuit diagram shown in Figure 3, the signal source Si again possesses the modulator M0 in which the signal is translated into an intermediate frequency position with the aid of the carrier supplied by the converter generator UGl and is then conducted to the upwards mixer M2'.
The converter generator UG2' is a generator which may be switched over in res-pect of its frequency and which is controlled via a control input ~not marked) by the pseudo-noise-pulse-sequence of the pseudo-noise-generator PG. The up-wards mixer M2' is designed to possess a very wide band and at its output is connected to the transmi.tting antenna SA. The pseudo-noise-generator PG is itself controlled by the clock frequency of the clock generator TG. The con-verter generators UGl and UG2' are also synchronised via the clock generator.
In accordance with Figure 4, the transmitted signal which is in-coming at the receiving antenna EA and which has been spread in respect of its band width is transformed in the downwards mixer M3' into the original band ,, ` width in the intermediate frequency level, by switching over the converter ~ generator UG2', similarly as at the transmitting end, by the identical pseudo-.~: noise-sequence of the receiving-end pseudo-noise-generator PG. The synchronis-;.- ing circuit SS is connected via its two inputs on the one hand to the input ~ end of the downwards mixer M3' and on the other hand to the output of the - converter generator UG2' whose freauency has been switched over. The other . 30 assemblies shown in Figure 4 are identical to the assemblies shown in Figure - A _ 9 _ .. . .
1091~
2 which bear the s~me references, including functioned symbols. Therefore these do not require to be explained again in detail.
The converter generators UGl and UG2 which are synchronised by the clock frequency of the clock generator TG can be embodied in different ways, as shown in Figures 5 to 8. For improved understanding, the fundamental pulse generator TG and the mixer M have been additionally entered in Figures 5 to 8.
In the first preferred embodiment shown in Figure 5, the con-verter generator consists of a frequency multiplier FV which multiplies the clock frequency by the factor n. This embodiment is particularly suitable for the construction of the converter generator UGl shown in Figures 1 and 3, as generally the carrier power for these input end modulators can be kept low.
The embodiments shown in Figures 6 to 8, which employ a Gunn oscillator G0 are particularly suitable for the construction of the converter generator UG2 for the upwards mixer. In the realisation shown in Figure 6, the converter generator consists of an injection-synchronised Gunn oscillator GO.
The synchronising input of the Gunn oscillator is supplied with a signal which is obtained from the clock frequency by means of the frequency multiplier FV
and which oscillates at the fundamental frequency of the Gunn oscillator or a subharmonic thereof.
In the embodiment in Figure 7, the converter generator consists of a controllable Gunn oscillator GO whose output together with the output of the clock generator TG which is supplied via a frequency multiplier FV is con-ducted to a phase comparator PV which~ in dependence upon a phase deviation, produces a control signal for the Gunn oscillator which here is obtained via a regulating device R.
In the embodiment in Figure 8, the converter generator is again ; constructed with a controllable Gunn oscillator GO whose output, together with the output of the clock generator TG supplied via the frequency multiplier FVJ feeds the mixer M4. The output of the mixer is connected to a low-pass A
filter TP via which the difference frequency is conducted to the one input of the phase comparator PV'. The other input of the phase comparator is connected to the output of a low frequency reference oscillator RO. The output voltage of the phase comparator acts upon the control input of the Gunn oscillator via the regulating device R. This embodiment has the advantage that the frequency of the Gunn oscillator does not require to be a whole-numbered multiple of the clock frequency. Furthermore, in this case any phase jitter in the clock generator TG cannot spread to the Gunn oscillator.
The arrangements, in particular of Figures 6 to 8 are also basi-cally suitable for the construction of a converter generator UG2' as shown in Figures 3 and 4. For example a converter generator of this type could in each case consist of two identical converter generators as shown in Figures 6 to 8, possessing different frequencies and being connected to the input of the mixer for the carrier oscillator via a change-over switch which is control-led by the pseudo-noise-generator.
. ~ .
"; .
,. .
,'' : .
~ A
::
The converter generators UGl and UG2 which are synchronised by the clock frequency of the clock generator TG can be embodied in different ways, as shown in Figures 5 to 8. For improved understanding, the fundamental pulse generator TG and the mixer M have been additionally entered in Figures 5 to 8.
In the first preferred embodiment shown in Figure 5, the con-verter generator consists of a frequency multiplier FV which multiplies the clock frequency by the factor n. This embodiment is particularly suitable for the construction of the converter generator UGl shown in Figures 1 and 3, as generally the carrier power for these input end modulators can be kept low.
The embodiments shown in Figures 6 to 8, which employ a Gunn oscillator G0 are particularly suitable for the construction of the converter generator UG2 for the upwards mixer. In the realisation shown in Figure 6, the converter generator consists of an injection-synchronised Gunn oscillator GO.
The synchronising input of the Gunn oscillator is supplied with a signal which is obtained from the clock frequency by means of the frequency multiplier FV
and which oscillates at the fundamental frequency of the Gunn oscillator or a subharmonic thereof.
In the embodiment in Figure 7, the converter generator consists of a controllable Gunn oscillator GO whose output together with the output of the clock generator TG which is supplied via a frequency multiplier FV is con-ducted to a phase comparator PV which~ in dependence upon a phase deviation, produces a control signal for the Gunn oscillator which here is obtained via a regulating device R.
In the embodiment in Figure 8, the converter generator is again ; constructed with a controllable Gunn oscillator GO whose output, together with the output of the clock generator TG supplied via the frequency multiplier FVJ feeds the mixer M4. The output of the mixer is connected to a low-pass A
filter TP via which the difference frequency is conducted to the one input of the phase comparator PV'. The other input of the phase comparator is connected to the output of a low frequency reference oscillator RO. The output voltage of the phase comparator acts upon the control input of the Gunn oscillator via the regulating device R. This embodiment has the advantage that the frequency of the Gunn oscillator does not require to be a whole-numbered multiple of the clock frequency. Furthermore, in this case any phase jitter in the clock generator TG cannot spread to the Gunn oscillator.
The arrangements, in particular of Figures 6 to 8 are also basi-cally suitable for the construction of a converter generator UG2' as shown in Figures 3 and 4. For example a converter generator of this type could in each case consist of two identical converter generators as shown in Figures 6 to 8, possessing different frequencies and being connected to the input of the mixer for the carrier oscillator via a change-over switch which is control-led by the pseudo-noise-generator.
. ~ .
"; .
,. .
,'' : .
~ A
::
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Arrangement for information transmission in which a transmitting end is supplied with an upwards mixer and with a first converter generator for the purpose of producing a trans-mitting signal, a band spread being effected by means of a pseudo-noise-sequence and in which a receiving end is supplied with a downwards mixer and with a second converter generator for the purpose of producing an if-signal, said band spread being cancelled by means of an identical pseudo-noise-sequence prior to actual demodulation, wherein at the transmitting end at least the converter generator for the upwards mixer is synchro-nised by a clock frequency produced by a first clock generator of a code generator which produces the pseudo-noise-sequence, and at the receiving end at least said second converter generator, for the downwards mixer, is synchronised by a clock frequency produced by a controllable second clock generator of the code generator which produces the identical pseudo-noise-sequence as at the transmitting end, and wherein at the receiv-ing end the second clock generator is controlled from an input signal by means of a synchronising circuit.
2. Arrangement as claimed in claim 1, wherein at the transmitting end the said one converter generator is in the form of a frequency multiplier which is connected at its input to said first clock generator.
3. Arrangement as claimed in claim 1, wherein at the re-ceiving end the said one converter generator is in the form of a frequency multiplier which is connected at its input to said first clock generator.
4. Arrangement as claimed in claim 1, wherein at the transmitting end at least one converter generator is in the form of an injection-synchronised Gunn oscillator whose synchro-nising input is supplied with the output of said first clock generator via a frequency multiplier.
5. Arrangement as claimed in claim 1, wherein at the receiving end at least one converter generator is in the form of an injection-synchronised Gunn oscillator whose synchronising input is supplied with the output of said second clock generator via a frequency multiplier.
6. Arrangement as claimed in claim 1, wherein at the transmitting end the said one converter generator is in the form of a Gunn oscillator which is controllable in respect of its frequency, and whose control signal is obtained from the phase comparison of the Gunn oscillator output and the output of a frequency multiplier which at its input is fed by said first clock generator.
7. Arrangement as claimed in claim 1, wherein at the receiving end said second converter generator is in the form of a Gunn oscillator which is controllable in respect of its frequency by means of a control signal obtained from a phase comparison of the Gunn oscillator output and the output of a frequency multiplier which at its input is fed by said second clock generator.
8. Arrangement as claimed in claim 1, wherein at the transmitting end said first converter generator is a Gunn oscillator which is controllable in respect of its frequency, and in which the output of the Gunn oscillator and the output of a frequency multiplier which at its input is fed by the clock generator are mixed in a mixer to form a difference signal which is compared in phase with the output of a low-frequency reference oscillator in a phase comparator and wherein the con-trol signal for the Gunn oscillator is obtained from this phase comparator.
9. Arrangement as claimed in claim 1, wherein at the receiving end said second converter generator is a Gunn oscilla-tor which is controllable in respect of its frequency, and in which the output of the Gunn oscillator and the output of a frequency multiplier which at its input is fed by the clock generator are mixed in a mixer to form a difference signal which is compared in phase with the output of a low-frequency reference oscillator in a phase comparator and wherein the control signal for the Gunn oscillator is obtained from this phase comparator.
10. Arrangement as claimed in claim 1, wherein the receiv-ing-end synchronising circuit is a delay locked loop, which synchronises the clock generator in dependence upon the agree-ment between the pseudo-noise-sequence contained in the input signal with the identical sequence produced by the receiving-end pseudo-noise-generator.
11. Arrangement as claimed in claim 1 wherein at the receiving-end said second converter generator is connected via a change-over switch selectively to the clock generator and to another auxiliary oscillator tuned to the theoretical frequency of said first clock generator.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2450727A DE2450727C1 (en) | 1974-10-25 | 1974-10-25 | Arrangement for information transfer |
| DEP2450727.5 | 1974-10-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1091298A true CA1091298A (en) | 1980-12-09 |
Family
ID=5929156
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA238,232A Expired CA1091298A (en) | 1974-10-25 | 1975-10-24 | System for transmission of information |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US4319358A (en) |
| CA (1) | CA1091298A (en) |
| DE (1) | DE2450727C1 (en) |
| DK (1) | DK476575A (en) |
| FR (1) | FR2435171A1 (en) |
| GB (1) | GB1585859A (en) |
| IT (1) | IT1043558B (en) |
| NL (1) | NL161639C (en) |
| NO (1) | NO144184C (en) |
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| DE3129912C2 (en) * | 1981-07-29 | 1987-11-12 | Siemens AG, 1000 Berlin und 8000 München | High-frequency radio transmitter for pseudo-random phase-modulated signals |
| DE3138523A1 (en) * | 1981-09-28 | 1983-04-07 | Siemens AG, 1000 Berlin und 8000 München | METHOD FOR TAKE-OFF SECURE FREQUENCY BAND-COMPRESSED TRANSMISSION OF VOICE SIGNALS |
| US4688257A (en) * | 1984-07-17 | 1987-08-18 | General Electric Company | Secure wireless communication system utilizing locally synchronized noise signals |
| US4630283A (en) * | 1985-07-17 | 1986-12-16 | Rca Corporation | Fast acquisition burst mode spread spectrum communications system with pilot carrier |
| US4639932A (en) * | 1985-08-29 | 1987-01-27 | Rca Corporation | Clock rate spread spectrum |
| FR2635191B1 (en) * | 1988-08-05 | 1990-10-05 | Merlin Gerin | METHOD AND DEVICE FOR CONTROLLING A QUASI-CLOSED ELECTROMAGNETIC SCREEN |
| US5121407A (en) * | 1990-09-27 | 1992-06-09 | Pittway Corporation | Spread spectrum communications system |
| CN1088035A (en) * | 1992-04-15 | 1994-06-15 | 客运电迅传送有限公司 | Signal distribution system |
| US5760700A (en) * | 1992-05-02 | 1998-06-02 | Electronics Research And Design Uk Ltd. | Security system with succession of codes |
| GB2269691A (en) * | 1992-05-02 | 1994-02-16 | K & K Audio Tech Ltd | Security systems. |
| US5539775A (en) * | 1993-03-17 | 1996-07-23 | Micron Technology, Inc. | Modulated spread spectrum in RF identification systems method |
| US5459758A (en) * | 1993-11-02 | 1995-10-17 | Interdigital Technology Corporation | Noise shaping technique for spread spectrum communications |
| AR011440A1 (en) * | 1997-02-12 | 2000-08-16 | Abb Power T & D Co | ELECTRONIC MEASUREMENT PROVISION |
| US7046682B2 (en) * | 1997-02-12 | 2006-05-16 | Elster Electricity, Llc. | Network-enabled, extensible metering system |
| US6088659A (en) * | 1997-09-11 | 2000-07-11 | Abb Power T&D Company Inc. | Automated meter reading system |
| US6700902B1 (en) | 1998-10-19 | 2004-03-02 | Elster Electricity, Llc | Method and system for improving wireless data packet delivery |
| US6867707B1 (en) | 2002-04-24 | 2005-03-15 | Elster Electricity, Llc | Automated on-site meter registration confirmation using a portable, wireless computing device |
| US7119713B2 (en) * | 2002-06-27 | 2006-10-10 | Elster Electricity, Llc | Dynamic self-configuring metering network |
| US20040113810A1 (en) * | 2002-06-28 | 2004-06-17 | Mason Robert T. | Data collector for an automated meter reading system |
| US7227350B2 (en) * | 2004-03-18 | 2007-06-05 | Elster Electricity, Llc | Bias technique for electric utility meter |
| US7315162B2 (en) * | 2004-03-18 | 2008-01-01 | Elster Electricity, Llc | Reducing power consumption of electrical meters |
| US7239250B2 (en) | 2004-04-26 | 2007-07-03 | Elster Electricity, Llc | System and method for improved transmission of meter data |
| US7262709B2 (en) * | 2004-04-26 | 2007-08-28 | Elster Electricity, Llc | System and method for efficient configuration in a fixed network automated meter reading system |
| US7187906B2 (en) * | 2004-04-26 | 2007-03-06 | Elster Electricity, Llc | Method and system for configurable qualification and registration in a fixed network automated meter reading system |
| US20050251401A1 (en) * | 2004-05-10 | 2005-11-10 | Elster Electricity, Llc. | Mesh AMR network interconnecting to mesh Wi-Fi network |
| US20050251403A1 (en) * | 2004-05-10 | 2005-11-10 | Elster Electricity, Llc. | Mesh AMR network interconnecting to TCP/IP wireless mesh network |
| US7142106B2 (en) * | 2004-06-15 | 2006-11-28 | Elster Electricity, Llc | System and method of visualizing network layout and performance characteristics in a wireless network |
| US7176807B2 (en) * | 2004-09-24 | 2007-02-13 | Elster Electricity, Llc | System for automatically enforcing a demand reset in a fixed network of electricity meters |
| US7170425B2 (en) * | 2004-09-24 | 2007-01-30 | Elster Electricity, Llc | System and method for creating multiple operating territories within a meter reading system |
| US7702594B2 (en) * | 2004-09-24 | 2010-04-20 | Elster Electricity, Llc | System and method for automated configuration of meters |
| US7742430B2 (en) * | 2004-09-24 | 2010-06-22 | Elster Electricity, Llc | System for automated management of spontaneous node migration in a distributed fixed wireless network |
| US7327998B2 (en) * | 2004-12-22 | 2008-02-05 | Elster Electricity, Llc | System and method of providing a geographic view of nodes in a wireless network |
| US20060206433A1 (en) * | 2005-03-11 | 2006-09-14 | Elster Electricity, Llc. | Secure and authenticated delivery of data from an automated meter reading system |
| US7308370B2 (en) | 2005-03-22 | 2007-12-11 | Elster Electricity Llc | Using a fixed network wireless data collection system to improve utility responsiveness to power outages |
| US20060224335A1 (en) * | 2005-03-29 | 2006-10-05 | Elster Electricity, Llc | Collecting interval data from a relative time battery powered automated meter reading devices |
| US8384582B2 (en) * | 2005-06-03 | 2013-02-26 | Space Engineering S.P.A. | Active transponder, particularly for synthetic aperture radar, or SAR, systems |
| US7495578B2 (en) * | 2005-09-02 | 2009-02-24 | Elster Electricity, Llc | Multipurpose interface for an automated meter reading device |
| US7308369B2 (en) * | 2005-09-28 | 2007-12-11 | Elster Electricity Llc | Ensuring automatic season change demand resets in a mesh type network of telemetry devices |
| US20070147268A1 (en) * | 2005-12-23 | 2007-06-28 | Elster Electricity, Llc | Distributing overall control of mesh AMR LAN networks to WAN interconnected collectors |
| US7427927B2 (en) * | 2006-02-16 | 2008-09-23 | Elster Electricity, Llc | In-home display communicates with a fixed network meter reading system |
| US7545285B2 (en) * | 2006-02-16 | 2009-06-09 | Elster Electricity, Llc | Load control unit in communication with a fixed network meter reading system |
| US8073384B2 (en) * | 2006-12-14 | 2011-12-06 | Elster Electricity, Llc | Optimization of redundancy and throughput in an automated meter data collection system using a wireless network |
| US8320302B2 (en) * | 2007-04-20 | 2012-11-27 | Elster Electricity, Llc | Over the air microcontroller flash memory updates |
| NZ586190A (en) | 2007-12-26 | 2013-05-31 | Elster Electricity Llc | A utility meter network wherein meters can transmit electrical and other readings to a collector by using other meters as repeaters |
| US8525692B2 (en) * | 2008-06-13 | 2013-09-03 | Elster Solutions, Llc | Techniques for limiting demand from an electricity meter with an installed relay |
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| US3128465A (en) * | 1961-07-27 | 1964-04-07 | Nat Company Inc | Timing synchronization by radio frequency communication |
| US3706933A (en) * | 1963-09-17 | 1972-12-19 | Sylvania Electric Prod | Synchronizing systems in the presence of noise |
| US3404230A (en) * | 1964-07-24 | 1968-10-01 | Ibm | Frequency corrector for use in a data transmission system |
| US3475558A (en) * | 1964-09-01 | 1969-10-28 | Magnavox Co | Time gated pseudonoise multiplexing system |
| DE1466514B2 (en) * | 1965-06-12 | 1970-12-10 | Telefunken Patentverwertungsgesellschaft Mbh, 7900 Ulm | Volume effect oscillator |
| DE1905532B2 (en) * | 1968-10-16 | 1971-06-03 | CIRCUIT FOR SYNCHRONIZATION OF THE TAKE AND OR CARRIER FREQUENCY IN THE PULSE-BULK TRANSMISSION OF DIGITAL SIGNALS VIA NEWS SATELLITES BETWEEN SEVERAL GROUND STATIONS USING TIME MULTIPLEX | |
| US3714573A (en) * | 1970-05-06 | 1973-01-30 | Hazeltine Corp | Spread-spectrum position monitoring system |
| JPS509663B1 (en) * | 1970-12-14 | 1975-04-15 | ||
| DE2146478C3 (en) * | 1971-09-17 | 1978-12-14 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | Circuit arrangement for initial synchronization in code division multiplex transmission systems |
| GB1407635A (en) * | 1972-11-28 | 1975-09-24 | Standard Telephones Cables Ltd | Oscillator arrangement using solid state oscillator device |
-
1974
- 1974-10-25 DE DE2450727A patent/DE2450727C1/en not_active Expired
-
1975
- 1975-09-09 GB GB37004/75A patent/GB1585859A/en not_active Expired
- 1975-10-16 NL NL7512133.A patent/NL161639C/en active
- 1975-10-21 IT IT28538/75A patent/IT1043558B/en active
- 1975-10-22 FR FR7532272A patent/FR2435171A1/en active Granted
- 1975-10-22 NO NO753549A patent/NO144184C/en unknown
- 1975-10-23 US US05/625,536 patent/US4319358A/en not_active Expired - Lifetime
- 1975-10-23 DK DK476575A patent/DK476575A/en not_active Application Discontinuation
- 1975-10-24 CA CA238,232A patent/CA1091298A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DK476575A (en) | 1982-04-28 |
| NO144184C (en) | 1981-07-08 |
| NO144184B (en) | 1981-03-30 |
| FR2435171A1 (en) | 1980-03-28 |
| US4319358A (en) | 1982-03-09 |
| IT1043558B (en) | 1980-02-29 |
| FR2435171B1 (en) | 1982-06-04 |
| DE2450727C1 (en) | 1979-11-29 |
| GB1585859A (en) | 1981-03-11 |
| NL161639C (en) | 1980-02-15 |
| NO753549L (en) | 1979-07-16 |
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