CA2113839C - Telecommunication device for the deaf with interrupt and pseudo-duplex capability - Google Patents
Telecommunication device for the deaf with interrupt and pseudo-duplex capability Download PDFInfo
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- CA2113839C CA2113839C CA002113839A CA2113839A CA2113839C CA 2113839 C CA2113839 C CA 2113839C CA 002113839 A CA002113839 A CA 002113839A CA 2113839 A CA2113839 A CA 2113839A CA 2113839 C CA2113839 C CA 2113839C
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- 206010011878 Deafness Diseases 0.000 title claims abstract description 36
- 238000004891 communication Methods 0.000 claims abstract description 49
- 230000005540 biological transmission Effects 0.000 claims abstract description 43
- 238000000034 method Methods 0.000 claims description 9
- 238000012360 testing method Methods 0.000 claims description 9
- 230000000007 visual effect Effects 0.000 claims description 6
- 230000011664 signaling Effects 0.000 claims 1
- 208000029108 46,XY sex reversal 8 Diseases 0.000 description 86
- 230000008901 benefit Effects 0.000 description 6
- 230000006870 function Effects 0.000 description 3
- 230000000737 periodic effect Effects 0.000 description 3
- 235000010582 Pisum sativum Nutrition 0.000 description 2
- 240000004713 Pisum sativum Species 0.000 description 2
- 150000001768 cations Chemical class 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- XUKUURHRXDUEBC-KAYWLYCHSA-N Atorvastatin Chemical compound C=1C=CC=CC=1C1=C(C=2C=CC(F)=CC=2)N(CC[C@@H](O)C[C@@H](O)CC(O)=O)C(C(C)C)=C1C(=O)NC1=CC=CC=C1 XUKUURHRXDUEBC-KAYWLYCHSA-N 0.000 description 1
- 206010010071 Coma Diseases 0.000 description 1
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- 101100042793 Gallus gallus SMC2 gene Proteins 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
- H04M11/06—Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors
- H04M11/066—Telephone sets adapted for data transmision
Abstract
A telecommunication device for the deaf (12, 14, 16, 20, 22, 24, 26, 28) operates under conventional Baudot communication protocol, but has enhanced features enabling it to handle interrupts either from a conventional or a similar TDD. The improved TDD is also capable of pseudo-duplex communication with a similar TDD in which each device transmits packets of characters alternatively to the other thus making it appear to the users that simultaneous transmission is occuring. The implementation of these features is done in such a way that the TDD is fully capable of communication with existing TDD devices and the device obeys normal rules and conventions for Baudot communication.
Description
Ai '~V~'w3/23946 ~ ~ ~ ~ ~ ~ ~ PCf/L)S93/04753 ~. 0 _~,_ TELECO~M~JNxCA,TION DEVICE ~'O~t THE DEAF
WITH ~NTIEF~RUPT AND PSEUDO--DUPLEX CAPAEILITY
v' Field of the Invention ' The pres~nt invention relates to telecor~nunication devices for the deaf in gen~ral, and, in particular, to .;
:
. ' improve telecommuni~a~tion devices for the deaf which offer increased conversation-like ~bi~:ity w'~ile maintaining ~i compatibility with satiating dev3,d~s already in use.
,;
B~~ckr~,xound of the Invention Persons who ass deaf or hea=ing impaired who cannot ~i hear raell eno~gth to use ~h~ telephone commonly make use of c~~nunication teryainal~ sp~cifically construdted in design '.; to enable such pets~ns to convers~ over telephone lines.
Such d~vices are refereed to as ~elecomynun,ication devices ,' 25' for the deaf, or TDDs, anti inclaade b~th a keyboard and a c3aapl~y connected t~ t~,e telephone thr~ugh a m~dean fi 4znodulat~rlde~aodu3:ator, . The na~d~a i~ typ3.cally built J
by hard wiring directly to a i~ato a TDD c~nnec~~d dither tel~plaon~ line or hrdugla an acoustic coupler which c~upl~s lth~ m~deyn to a noac~nal .telephone handset. TDD~s are n~ranally capabh' of ~r~ns~nit~ing information over a ',i te~.ep~~ne line by nteaz~~ of coded t~nes to another ., thc opposite end of the compatible TDD cor.~ected ~t , telepla~ne line through another modem.
T~eb~ ark s,e~:cral protocols' that are used for : trans~itring digiaal information through analog lines such a~ teleph~ne li.nes: The most comm~nly used information :~;:a protocol zn the electronics industry is referred to as ";
ASCII (American Standard Code for Information 1,~
W~ 93/23946 ~ ~ ~ J ~ ~ ~ ~C'~'/US93104753 f,~..;~
-~-Interchange). The d~SCII code was designed for and is most commonly used for information interchange between ..
computers. However, largely due to historic reasons, TDD's have operated on a different protocol, originally developed specifically for TDD communication. This~~TDD
protocol is referred to here as the Baudot/Weitbrecht, or standard Baudot, and includes both a specific 5-bit Baudot code and a freguency shift keying (FSK) protocol of electronic communication. The standard Baudot communication is simplex, that is to say it is capable of only transmitting in one direction at one time.
Therefore, during normal TDD communication, one station must be silent while the other is transmitting: It has become a convention that one TDD user informs the other TDD user when it is the other user's turn to utilize the communication link.
The inability of the traditional Haudot/TDD
communicati~n networ~C to permit bi-directional or duplex communication of the network created by this form of ', 20 communications has been an inadequacy since its inception.
Under current TDD/Baudot'comrnunication protocols, if both users attesttg'~ to transmit at the same time, each station will only display t~ the user the characters it is transmitting: This is because standard Baudot TDD's are designed to dive priority to transmission. Since prior TDD's cannot receive data while transmitting, when transmitting standard TDDs make no attempt to receive inc~mi~ag characters. This crates obvious~difficulties in the us~ ~f TDD systems f~r communication between ~0 individuals and xnak~s such communication not similar to normal human communication. ads in even a brief monitoring ~~ oral c~mmunic~tion between hearing individuals will ~.ndicate, human speech i.s characterized by c~nstant ; interruptions anti interchange. The current TDD/Baudot communication network is incapable of handling such a.nterruptions and interjections, and hence is less similax to audible human conversations than would be desired in an idea. system .
~V~' 93/23946 ~ ~ ~ ~ ~ ~ ~ PCfBUS93/~D4°7~3 In addition, it is often desired that during a TDD
communication that one user be able to signal or interrupt the other user. Often, for example, one user may be launched onto a long description, or explanation, which the other user is already aware of or has heard before.
:i .
, In normal human audible conversation, a listener can v indicate to the speaker that he has already heard that part of th~ explanation. In TDD communication, due to the simplex nature of the communication link, the receiver is unable to communicate with the transmitter until the .;
transmission is complete. Since coz~ununicat~.ons can sometimes be quite long, this is a source of frustration and time delay, and hampers normal human tendencies during conversation. FIeretofore the standard Baudot/Weitbrecht network has been incapable of handling such tendencies.
:, ; There was one instance known of an attempt to permit ;
a.nterruption in a communication device operating under ~' Baudot protocol.. One of the early originators of TDD
communications in the United States, Tar. Weitbrecht instituted a 'news service' for the deaf community in the United States accessible by telephone. I~Lz~. Weitbrecht constructed what was, in sssenc~ a recording device, which played out a periodic news compilation in Baudot '" communication t~ any TDD that would dial the phone number assodiat~d with: the news servic~. In that time period, it was co~cnon for TDD's to listen for space tones (100 I3~rt~ ) c~n3;y, end to not even sense mark tones ( 1400 ~ert~e ) s~ rec~r~.v~.ng , ~DD w~uld ~4~ply aw~o~~e abagence of " space tones during a character meant mark., LTtilizing:this :
, ''' 30 characteristic, Weitbrecht constructed the news service device so that if is was to transrai.t a bit sequence of three marks (or 1's) at any point during the transz~i.ssion, the device would simply stop transmitting the mark tone and listen for tones from the communicating station. If tones ~rere sensed during the interval, the news service :'~ device would cease transmission. This feature was <;
transparent to users at that time since most TD~s of the , era did not detect mark tones. This characteristic is no .; longer true of modern electronic TDD's.
dV0 93/23946 ' ~ PfT/4.1~93/04753 ~~~~~J~ -4-,L
Summary of the Invention In accordance with the present invention, a __ a telecommunication device for the deaf is constructed which operates so as to observe two rules which constrain its '5 activity so as to permit interrupts and pseudo-duplex rJ
1J ' activity. The two rules are that the terminal is not ' permitted to transmit when it is receiving transmissions ;:
r from a device with which it is communicating. The second rule is that the terminal creates a pause in the ;, '~ 10 co~nmuni.cation line at periodic intervals of transmitted characters and, during that pause, senses for '- transmissions by the remote terminal. The combination of :i these two rules in the operation of a telecommunication device permits the device both to be interrupted, and 15 permits pseudo-duplex communication between two telecommunication devices for the deaf.
,x It is an object of the present invention to provide a telecommunication device for the deaf which is capable of .I
providing an interrupt signal from one user to another, 20 which is still compatible with and capable of communicating with existing TDD devices previously '~ installed ar~thin the deaf r_~mmn~aitv_ It is yet another object of the present invention to provide a telecommunidation deviee for the deaf which is '; ZS capable of prov3.ding two-way communication, or ;pseudo-duplex coma~ua~ication, while still being fully compatible with ~xi~ti~ag telec~mmuz~ication devices for the ~~af a~.r~ady 3:n~talled in the deaf community.
It i~ another object of the present invention to 3(7 provide a tel~com~aunication device' of the deaf which is capable of providing interrupt and pseudo-duplex ..,~i capabilities, while also being capable of c~mmunicating s with an enhanG~d TDD ~rotucol permitting faster speeds of r;
:~'~ c~mmunication .
,s 35 It is an advantage of the present invention in that it can be implemented totally in microcode, or firmware, y;a, where changes to existing TDD designs so as to permit cost--effective and convenient retrofitting of existing TDD's in the field so that the benefits of these enhanced .'... . ,', ", ' .',' , ., ;,;::, , ;,.~':..; .~:' , .:~;~~'~, r, :..:,,> " , . ~...~i .... ;..:~:... .,. :::... .. ';, n . . ;~; ~? , . . . r;, r, ..:.<.... a ; . , . ..
~ ~ 1 ~ 8 3 '' ~~r/us93/o47~~
W~' X3/23946 methods of TDD communication can be utilized by the existing community of TDD users.
the pseudo-duplex and interrupt cagabilities will also result in a net savings of on-line time and telephone costs as users can interrupt previously transm~.tted~
communications. This results also in more natural conversation-like communications. Also the interrupt capability allows for handling emergency communications more effectively.
Other objects, advantages, and features of the present invention will become apparent from the following specification wh~n taken in conjunction with the accompanying drawings.
Brief Description of the Dxawinus Fi=. 1 is a schematic diagram of a TDD hardware.
Fig.,:..2 illustrates schematic details of the analog circuit of Fig. 1.
Fig: 3 is a flow chart illustrating the method of operation of a terma.nal ~perating in accordance with the Present invention.
Descrigti~n of the Invention In accordance w~.th the gresent invention, a telecommunication d~vice for the deaf has built into its functioning an enh~need yet of protocols which enable it to coa~aaunicate with cs~nventional 8audot terminals and also :o t~ be capable ~f handling an interrupt situation and also handling bi-directi~n~l, or pseudo-duplex, communication.
the ay~ij.i~y~ to do both tlhe interrupt and th~
bi-directional c~~mtunication arises from the terminal following two,,relatively simple rules in its method of o~eratic~n. The first xu.le is that the terminal is constrained not to present carrier or characters on the communication line when the bther terminal with which it is communicating i~ presenting such characters. The second rule is that the terminal is constrained to present a pause, or null, on the communication tine at predetermined intervals, i..e. after the transmission of a ~c°rius~~~oa~5~
vvo g3iz3g~~ ~ .~ ~ 3 $ ~ 9 ' -6-specific number of characters. The implementation of these two rules in a telecommunications device enables '. such devices to interrupt each other, and to communicate ''~ in a pseudo-.duplex fashion to each other. The implementation of these rules does not prevent '' communication bettyeen such an improved TDD and a ';
.I
conventional TDDs :y Shown in Figure 1 is a schematic block diagram of the ;,.
function of a typical TDD. In the TDD of Figure 1, the user types on a keyboard indicated at 12 to input characters into a microprocessor indicated at 7,4.
'v Characters which are received or transmitted by the microprocessor are also displayed to the user'on a visual electronic display, indicated at 16. Characters may also ' 15 optionally be displayed by means of a hard copy printer, indicated at :18, which some TDD's include. Thus the keyboard serves as the source of input data characters and :..
either or both of the display 16 and the printer 28 serve as ultimate destinations for the data characters. The microprocessor l4 is largely responsible for the ,.
;
imglementation of the various timing and decoding functions of the TDD. The microprocessor has data and ->
address buss, jointly indicated at 20, which connect to a read--only memorZr ( RDM ) 2 2 and a random a cces s memory ( RAM
WITH ~NTIEF~RUPT AND PSEUDO--DUPLEX CAPAEILITY
v' Field of the Invention ' The pres~nt invention relates to telecor~nunication devices for the deaf in gen~ral, and, in particular, to .;
:
. ' improve telecommuni~a~tion devices for the deaf which offer increased conversation-like ~bi~:ity w'~ile maintaining ~i compatibility with satiating dev3,d~s already in use.
,;
B~~ckr~,xound of the Invention Persons who ass deaf or hea=ing impaired who cannot ~i hear raell eno~gth to use ~h~ telephone commonly make use of c~~nunication teryainal~ sp~cifically construdted in design '.; to enable such pets~ns to convers~ over telephone lines.
Such d~vices are refereed to as ~elecomynun,ication devices ,' 25' for the deaf, or TDDs, anti inclaade b~th a keyboard and a c3aapl~y connected t~ t~,e telephone thr~ugh a m~dean fi 4znodulat~rlde~aodu3:ator, . The na~d~a i~ typ3.cally built J
by hard wiring directly to a i~ato a TDD c~nnec~~d dither tel~plaon~ line or hrdugla an acoustic coupler which c~upl~s lth~ m~deyn to a noac~nal .telephone handset. TDD~s are n~ranally capabh' of ~r~ns~nit~ing information over a ',i te~.ep~~ne line by nteaz~~ of coded t~nes to another ., thc opposite end of the compatible TDD cor.~ected ~t , telepla~ne line through another modem.
T~eb~ ark s,e~:cral protocols' that are used for : trans~itring digiaal information through analog lines such a~ teleph~ne li.nes: The most comm~nly used information :~;:a protocol zn the electronics industry is referred to as ";
ASCII (American Standard Code for Information 1,~
W~ 93/23946 ~ ~ ~ J ~ ~ ~ ~C'~'/US93104753 f,~..;~
-~-Interchange). The d~SCII code was designed for and is most commonly used for information interchange between ..
computers. However, largely due to historic reasons, TDD's have operated on a different protocol, originally developed specifically for TDD communication. This~~TDD
protocol is referred to here as the Baudot/Weitbrecht, or standard Baudot, and includes both a specific 5-bit Baudot code and a freguency shift keying (FSK) protocol of electronic communication. The standard Baudot communication is simplex, that is to say it is capable of only transmitting in one direction at one time.
Therefore, during normal TDD communication, one station must be silent while the other is transmitting: It has become a convention that one TDD user informs the other TDD user when it is the other user's turn to utilize the communication link.
The inability of the traditional Haudot/TDD
communicati~n networ~C to permit bi-directional or duplex communication of the network created by this form of ', 20 communications has been an inadequacy since its inception.
Under current TDD/Baudot'comrnunication protocols, if both users attesttg'~ to transmit at the same time, each station will only display t~ the user the characters it is transmitting: This is because standard Baudot TDD's are designed to dive priority to transmission. Since prior TDD's cannot receive data while transmitting, when transmitting standard TDDs make no attempt to receive inc~mi~ag characters. This crates obvious~difficulties in the us~ ~f TDD systems f~r communication between ~0 individuals and xnak~s such communication not similar to normal human communication. ads in even a brief monitoring ~~ oral c~mmunic~tion between hearing individuals will ~.ndicate, human speech i.s characterized by c~nstant ; interruptions anti interchange. The current TDD/Baudot communication network is incapable of handling such a.nterruptions and interjections, and hence is less similax to audible human conversations than would be desired in an idea. system .
~V~' 93/23946 ~ ~ ~ ~ ~ ~ ~ PCfBUS93/~D4°7~3 In addition, it is often desired that during a TDD
communication that one user be able to signal or interrupt the other user. Often, for example, one user may be launched onto a long description, or explanation, which the other user is already aware of or has heard before.
:i .
, In normal human audible conversation, a listener can v indicate to the speaker that he has already heard that part of th~ explanation. In TDD communication, due to the simplex nature of the communication link, the receiver is unable to communicate with the transmitter until the .;
transmission is complete. Since coz~ununicat~.ons can sometimes be quite long, this is a source of frustration and time delay, and hampers normal human tendencies during conversation. FIeretofore the standard Baudot/Weitbrecht network has been incapable of handling such tendencies.
:, ; There was one instance known of an attempt to permit ;
a.nterruption in a communication device operating under ~' Baudot protocol.. One of the early originators of TDD
communications in the United States, Tar. Weitbrecht instituted a 'news service' for the deaf community in the United States accessible by telephone. I~Lz~. Weitbrecht constructed what was, in sssenc~ a recording device, which played out a periodic news compilation in Baudot '" communication t~ any TDD that would dial the phone number assodiat~d with: the news servic~. In that time period, it was co~cnon for TDD's to listen for space tones (100 I3~rt~ ) c~n3;y, end to not even sense mark tones ( 1400 ~ert~e ) s~ rec~r~.v~.ng , ~DD w~uld ~4~ply aw~o~~e abagence of " space tones during a character meant mark., LTtilizing:this :
, ''' 30 characteristic, Weitbrecht constructed the news service device so that if is was to transrai.t a bit sequence of three marks (or 1's) at any point during the transz~i.ssion, the device would simply stop transmitting the mark tone and listen for tones from the communicating station. If tones ~rere sensed during the interval, the news service :'~ device would cease transmission. This feature was <;
transparent to users at that time since most TD~s of the , era did not detect mark tones. This characteristic is no .; longer true of modern electronic TDD's.
dV0 93/23946 ' ~ PfT/4.1~93/04753 ~~~~~J~ -4-,L
Summary of the Invention In accordance with the present invention, a __ a telecommunication device for the deaf is constructed which operates so as to observe two rules which constrain its '5 activity so as to permit interrupts and pseudo-duplex rJ
1J ' activity. The two rules are that the terminal is not ' permitted to transmit when it is receiving transmissions ;:
r from a device with which it is communicating. The second rule is that the terminal creates a pause in the ;, '~ 10 co~nmuni.cation line at periodic intervals of transmitted characters and, during that pause, senses for '- transmissions by the remote terminal. The combination of :i these two rules in the operation of a telecommunication device permits the device both to be interrupted, and 15 permits pseudo-duplex communication between two telecommunication devices for the deaf.
,x It is an object of the present invention to provide a telecommunication device for the deaf which is capable of .I
providing an interrupt signal from one user to another, 20 which is still compatible with and capable of communicating with existing TDD devices previously '~ installed ar~thin the deaf r_~mmn~aitv_ It is yet another object of the present invention to provide a telecommunidation deviee for the deaf which is '; ZS capable of prov3.ding two-way communication, or ;pseudo-duplex coma~ua~ication, while still being fully compatible with ~xi~ti~ag telec~mmuz~ication devices for the ~~af a~.r~ady 3:n~talled in the deaf community.
It i~ another object of the present invention to 3(7 provide a tel~com~aunication device' of the deaf which is capable of providing interrupt and pseudo-duplex ..,~i capabilities, while also being capable of c~mmunicating s with an enhanG~d TDD ~rotucol permitting faster speeds of r;
:~'~ c~mmunication .
,s 35 It is an advantage of the present invention in that it can be implemented totally in microcode, or firmware, y;a, where changes to existing TDD designs so as to permit cost--effective and convenient retrofitting of existing TDD's in the field so that the benefits of these enhanced .'... . ,', ", ' .',' , ., ;,;::, , ;,.~':..; .~:' , .:~;~~'~, r, :..:,,> " , . ~...~i .... ;..:~:... .,. :::... .. ';, n . . ;~; ~? , . . . r;, r, ..:.<.... a ; . , . ..
~ ~ 1 ~ 8 3 '' ~~r/us93/o47~~
W~' X3/23946 methods of TDD communication can be utilized by the existing community of TDD users.
the pseudo-duplex and interrupt cagabilities will also result in a net savings of on-line time and telephone costs as users can interrupt previously transm~.tted~
communications. This results also in more natural conversation-like communications. Also the interrupt capability allows for handling emergency communications more effectively.
Other objects, advantages, and features of the present invention will become apparent from the following specification wh~n taken in conjunction with the accompanying drawings.
Brief Description of the Dxawinus Fi=. 1 is a schematic diagram of a TDD hardware.
Fig.,:..2 illustrates schematic details of the analog circuit of Fig. 1.
Fig: 3 is a flow chart illustrating the method of operation of a terma.nal ~perating in accordance with the Present invention.
Descrigti~n of the Invention In accordance w~.th the gresent invention, a telecommunication d~vice for the deaf has built into its functioning an enh~need yet of protocols which enable it to coa~aaunicate with cs~nventional 8audot terminals and also :o t~ be capable ~f handling an interrupt situation and also handling bi-directi~n~l, or pseudo-duplex, communication.
the ay~ij.i~y~ to do both tlhe interrupt and th~
bi-directional c~~mtunication arises from the terminal following two,,relatively simple rules in its method of o~eratic~n. The first xu.le is that the terminal is constrained not to present carrier or characters on the communication line when the bther terminal with which it is communicating i~ presenting such characters. The second rule is that the terminal is constrained to present a pause, or null, on the communication tine at predetermined intervals, i..e. after the transmission of a ~c°rius~~~oa~5~
vvo g3iz3g~~ ~ .~ ~ 3 $ ~ 9 ' -6-specific number of characters. The implementation of these two rules in a telecommunications device enables '. such devices to interrupt each other, and to communicate ''~ in a pseudo-.duplex fashion to each other. The implementation of these rules does not prevent '' communication bettyeen such an improved TDD and a ';
.I
conventional TDDs :y Shown in Figure 1 is a schematic block diagram of the ;,.
function of a typical TDD. In the TDD of Figure 1, the user types on a keyboard indicated at 12 to input characters into a microprocessor indicated at 7,4.
'v Characters which are received or transmitted by the microprocessor are also displayed to the user'on a visual electronic display, indicated at 16. Characters may also ' 15 optionally be displayed by means of a hard copy printer, indicated at :18, which some TDD's include. Thus the keyboard serves as the source of input data characters and :..
either or both of the display 16 and the printer 28 serve as ultimate destinations for the data characters. The microprocessor l4 is largely responsible for the ,.
;
imglementation of the various timing and decoding functions of the TDD. The microprocessor has data and ->
address buss, jointly indicated at 20, which connect to a read--only memorZr ( RDM ) 2 2 and a random a cces s memory ( RAM
2~. Appropriate can~rol lines 26 and 28 connect to the ROM 22 and RAM 24 so as to control the operation thereof.
J~ The RttM is intended t~ contain the program which dictates the functional o~e~xation of the microprocessor 14. The RA~i a.s uta.lized as a holding place or stack for data coming into or out of the TDD. In some TDD's, the micreaprocess~r, the RhM and the ~~M are all combined in a ' al singae inte~ratedvcircuit, while in ~thers they are separa~t~ circuits.
:z:
~s an additional output, the microprocessor connects ' through analog circuitry 30 to one of three separate a outputs. The analog circuitry 30 is, most preferably, a y', modem. One output of the analog circuitry 30 could be a telephone direct connect circuitry 32 which connects the modem directly by hardwiring into the telephone network.
2~~.3~~9 ''WC' ~3/23946 P~1"/US93/~4753 -7_ A second possible output from the analog circuitry is i through an acoustic output circuit 34 intended to audibly connect through a speaker 38 to the microphone of a ! telephone handset. At 36 is indicated acoustic input i 5 circuitry connected to a microphone 40, which is intended to audibly couple to the speaker in a telephone handset.
The acoustic output speaker and the acoustic input microphone may be coneected through a so-called "acoustic coupler" to a conventional telephone handset. In any TDD, either the hardwired connection or the acoustic_connection is provided, and sometimes both. It is also envisioned ' that the telephone line need not be a physical link. A
TDD could be made to operate as a cordless phone or through a cellular telephone system rather than through a conventional telephone two-wire connection.
i Shown in Fib. 2 is a simplified schematic of how the input and outputs of tlhe analog circuitry would work. For data coming l.nt0 the terdtl~.nal, the aud.lble input from a 's microphone or t~Iephone line is translated into electronic comport~nts and then presented to an amglif~.er 42. The output of the aa~plifi:er is presented to two phase-1~ckedrloops 44. One of the phase locked-loops 44 is tuned to a frequency of 1800 Hertz, while the other i phase-locked-loop 44 is tuned to a frequency of 1400 Hertz. 1800 Hegtz and 1400 Hertz are the designated carrier fregu~ncies for st~r~dard B~udot communication. On the ~utput side of th~ circuitry, output signals are a presented tc~ ~a I,PF (low pass filters transaait wave shaping circuit 46: The ~utput of that circuit, consisting of , alternate 1400 and 1800 Hertz signals, is presented to an ky amplifier 48 which 3.~ hardwired to the speaker ar te7.eph~ne line.
In normal Haudot communications with existing TDD's, each TDI3 communicates at 45.5 baud in a simplex mode. Tn some countries, the protocol is the same but the speed is 50 baud. That is to say each TDD transmits a character on ;;
the line whenever a key is pressed at the TDD. As a result, in order to approximate the give-and-take of nara~a.l conversation, TDD users generally have to indicate P~TlUS93/0~8753 ,~.,.~
WCi 93J23946 ~ ~ ~ ~
.
to the other user when the user that has the floor is ending that particular communication. For example, it is q uite common convention in the United States to type the j letters "GA" as an abbreviation for "go ahead" at the end of a text string to indicate to the other user that it is i ' his or her turn to type. This procedure is awkward and not like normal. conversation. Also, occasionally users wish to interrupt and, regardless of the constraints of i their machine, do attempt to type keys inta their machine 1 10 while receiving data. Such attempts to interrupt are typically not successful since the station transmitting data does not monitor the line for incoming data.
The TDD of the present invention is canstrained not to even attempt truly simultaneous communication. The v 15 imgroved TDD described here is simply programmed not to ,i transmit data when data is being recea:ved. This concept is directly opposite to the conv~nta.onal operation of TDD~s, but is effective if utilized as described here. It is a relatively si~tple matter that, when the 24 micro rocessor senses that a ke has been y pressed during data reception and which is int~nd~d to ultimately transmit a character t~ the rem~te station, for the microprocessor first t~ best whether analog data is being received; If data is being received, the microprocessor 25 is constbained by the software not to iz~mediat~I.y output he character onto the transmit line but, instead, to store the a 3 ppr~ riate characgers which have been entered by th~ user into the RAM. Typed characters are also stored in a queue or stack dur~.ng all ti.~nes of data 3a r~ceptio~a: The u~er~ may continue to type, end the ctaarac~ers are ea~tered by the keyboard, and are placed ante the ~ ua~tii such time as c~mmunication from the r,ea~note station h~~ ceased.
; When it is ta.m~ for the station a:n accordance with , 35 the present invention to transmit, the improved TDD
w, transmits characters either directly from its keyboard or , from the buffer composed of the RAM, out through the transmission line. The pseudo-duplex capable TDD of this invention will, however, pause periodically during the V'/P 3/23946 ~ ~ ~ ~ ~ ~ ~ P'~G'1°/US93104753 transmit data stream. The device is programmed to pause after the transmission of a pre-determined number of characters. The purpose of the pause is far the terminal to test during the pause whether input data is being received. In other words, the pause serves as an interrupt window for the other communicating machine.
Since the device is constrained not to transmit when receiving, if, during a pause, the other remote machine ; begins transmitting the local terminal will cease , transmission. In this way, most of the situations ira r;
which the two terminals would simultaneously transmit data are avoided. It is still possible occasionally for '~s simultaneous data transmissions to occur, when both stations simultaneously transmit data onto the line, but ,,'~ 15 these situations will be quite rare.
The number of characters which are transmitted by the . TDD in accordance with the present invention before a .,, pause is suDa~~ct to some variatian between two extremes.
fat one extreme, it is possible to present a pause on the transmission line .after the transmission of every single character. file this choice minimises the number of pot~r~tial data collisi~ns on the telephone ~.ine, it also ,>~ slows down the transmission when conducted at ordinary ~~a Baud~t transmission rates: Sinee Baudot operates 2S relatively slow in any event, ie: at 45.5 Baud, which appr~ximates 6 characters per second, adding an extra bit time ' or ~tw~ tc~ w~~r character might perceptively slow ~pwn tl~ae tscansm3.s~i~n by the terminal. At, its upper liait3.t, i.t is clearly possible to ~ impose such a pause every 72 cl~~act~rs, since the normal constraints of con~rent~.~nal Baudot cnmmu~nication protocols require that a carriage zetu~n end line feed be implemented every 72 characters folloured by a pause, originally imposed to allow for a mechanical TDD systems which must mechanically return the printing head. Thus there is an automatic pause time traditionally included in. Baudot/weitbrecht ' protocol at least every 72 characters within the data stream, by convention. In its preferred embodiment, it is ;~, :v? anticipated that the number of characters which will be WO 93/2394b p~/U593/04753 ~
1~SJJ
~~
.
transmitted in between pauses would be between 1 and '72, and most preferably between ~, and 10. Actual empiri_~al testing of terminals on a number of communication lines is necessary to determine which is the exact and optimum S number of characters to be transmitted between pauses.
The length of the pause after the packet of characters should be sufficient so as to permit settling of the communication line, a time period sufficient for the other terminal to commence data transmission, and a time period sufficient for the pausing station ~.o sense that data is being transmitted to it over the telephone line. These times can be varied over a wide range depending on the quality of the telephone netraork and the timing constraints of the hardware in the TDD. The normal bit time of conventional Baudot communication is aPProximately 22 milla.seconds. After transmitting Baudot tones, it can typically take some telephone lanes some ti.ane period for echoes, transients, and other chatter introduced on the line by previous communication signals to fade. In most modern t~lephon~ systems, a time period of five to fifty milliseconds is needed to permit such settling: A TDD in the accordance with the present inventaon pauses for ~ time period divided into two portions. The first portion is a pause for a sufficient time period,'su~la as l0 millisecond, to permit the t telephony line to settle. The second pause is for a suffici~nt tim~ pexi~d, such a~, 1~ to 44 mil~.is~oonds, a ~hidh is sufficient tigne for the transmitting teraninal to 3.nitiate tran~~issi~n and for th~ transmission to be sensed by the pausing ~t~~ion. An interrupt-competent and pseudo~duglex TDD constructed in accordance with the resent invention.will therefore often have to buffer data being typed a.n by the user , -: Duri.r~g time periods in which the user is typang at the keyboard, but the term~.nal is constrained fro$n transmitts.ng characters due to the receipt of characters from the remote terminal, the data characters being entered by the user would be stored in the random access memory in a stack or queue. Then, during th,e station's next interval for transmission, it P~1'/ x"1593104'753 Wr' X3/23946 ~11_ would transmit characters on a first-come first-serve basis out of the queue onto the transmission line.
This system is capable of operating either in conventional Baudot/Weitbrecht or in a newly designed enhanced ~audot communication grotocol. Neverthel,~ss, it is an advantage of the operation of this machine that it is capable of operating also with conventional TDD's, without any alteration to the conventional machines. Tf the TDD of the present invention is communicating with an otherwise conventional remote TDD, the remote terminal could occasionally lose characters if keys are pressed while ft is receiving. The pseudo-duplex TDD will tend to drop fewer characters since it cannot transmat~when the remote terminal is transmitting. In addition, any such losses at the remote terminal are minimized, since the TDD
in accordance with the present invention creates a pause at predetermined intervals, and when the first of those intervals occurs, the pseudo-duplex TDD will stop transnutting. Thereafter, the pseudo~duplex TDD will be able to receive whatever information is being transmitted by the stat3.on with Tahich it is communicating. Clearly the fewer the nuz~ber of characters transmitted between pauses, the fewer th'e number of characters which might be lost.
.As an o~ti~r~, .it may also be appropriate to include an interrupt ~igaaal in the TDD of the present invention.
If such an interrupt sign is implemented, the m~.cr~p~c~cess~r ~aauld as usual, monitor the input line during times it is not transmitting data to test for ~0 signals. The TDD would thus detect any data signal received during the periodic gauser even if the terminal still ~iad draracters to transmit. The microprocessor would then visually s~.gn~1 to the user fret an interrupt is be~.ng initiated by tre remote station. The visual interrupt sagnal c~uld consist of the word '°3.nterrupt" on the display, could consist of the display of a specially designated character not in the normal Baudot character set, such:as an asterisk or could consist of any characteristid character, ward or pattern designated for PC: t'/tJS93/U47S3 V1'~ 93/23946 ° f"""';
' -12-this purpose. Another alternative is to split the display into two sets (input and recoived characters) and the, user can be informed of the interrupt by noticing the split display. Then the user may cease typing on the keyboard, S to germit the transmission from the remote statiori"to be , .
y received by the terminal and displayed appropriately.
In the event that two interrupt-competent TDD's in y accordance with the present invention are communicating, missing transmitted data becomes an extremely unlikely vJ
~.0 event. In normal communication, when either one of the ';
two terminals is transmitting, the other terminal is c onstrained not to transmit. Then, since each station i when transmitting is constrained to step after a certain number of characters and present a pause, during that 15 pause the other station will gain control of the :n, communication line. Then t3~at station will transmit until ;: its turn to peas~. For example, if the persons at ;
stations A and B are both t~rping at the same time, one of PJ
the two TDD's at each station will initially gain control 20 ~f the comrauna.cation l9.ne, end transmit the predetermined numher ~rf charact~~rs. ~~~sume, for purposes of this example, that the number ~f transmitted characters is seven. Station A would transmit sbven characters to Station B, and Station ~ would be constrained not to 25 transmit during that interval. At the end of the would transmission of tie s~v~nth character, Station , peas~ and Station B ~rould ~eiz~ control ref the com~una.cata.on line and then communicate seven characters t~ Stat.l.on ~e. after that tame period, Station B would 30 pause; and Station ~ w~uld resume control ~f the com~unicati~n lines. In other words, each station would separately transmit tO the Other a burst of characters ' ,during alternate im~ periods. In this way, it would ~,f appear to the'us~ers as if a full duplex communication were 35 occurring. This form of communication is referred to here as gseudo-duplex, since the actual technical communications over the telephone line is in simplex, i.e.
with only one station able to communicate at an instant, yt s'i'r .s.: a~ "~ .,.,.
r~'~.~. ,.r~~::k, .....:..d:~~.w...e......etdre . ..... .. ,...:~a< ..
"y.:rr:o...ar.r.
..,..,N.,. ,...,.._:.i*.... ..,....._..m...... ..u...,o....1;1.*::e~.;..*i~%' Wt' ~3/23946 ~ ~ ~ ~ ~ ~ ~ P~.'1'/US93/04753 _~,3_ while the appearance to the users is of duplex, or two-way, communication.
Obviously, if a station is alternately both transmitting and receiving data in groups of small. numbers of characters, some provision must be made to make the display appropriate and readable to a user. At least two options are possible. One option is simply to have the user only see the information received from the foreign station. The other,~~a more preferable option, is to split the screen of the display on the terminal. This'split can be either vertical far one-line displays or horizontal if there is a two line or larger display. One portion of the split screen would be reserved for the characters being transmitted by the terminal and other portion of the split I5 screen ~~~uld display the characters being received from the remade terminal. Such split-screen operation is i entirely within the capability of the microprocessor to effectuate, the screen display being under software control in any event.
j Sh~wn in Figur~ 3 is ~ flow-chart representation of the workings of the te~m~.nal o~ Figures 1 and 2 operating in accordanc~ with the present invea~tion. At step 50, the microprocessor monitors the ~Ceyboard and the incoming telephony line for data: This step is perfox~ned in the normal fashion by which TDD°s perform these functions.
When a user p~ces~es a key the key selected by the user rep~esents'data which is accepted from the keyboard at method step 52: Most con~rentional prior TDD°s would immediately txans~a~a the character to the telephone li:ze.
In~t~ad the pseudo-duplex TDD first checks to ensure that no data is being received ~n the teie~hone line. If data i~ being received' he program branches and cantinues to receive the input data and buffer the output data until the incoming character stream ceases. This step is indicated at~55. Once the received data is stopped, the program may proceed back through the step of detecting whether data is being received at step 54. Once the situation arises where no data is being received, the program then pr~ceeds to step 56 where it transmits N
WO 93123946 PCI"1US93/04753 .~,..~
~~~~~c~l~
_24-characters of data from the keyboard. In this instance .Y
the letter I~ represents the numbers of letters in the, '. character packet which is transmitted by the pseudo-duplex a .
v TDD. As stated, the number N can be between 1 and ~2 and is preferably between 3 and 10. After the characters :.
packet has been transmitted, the program then determines 'd whether or not there are characters left to transmit. If ' all the characters have been transmitted the program can ,; return to its monitoring state at step 50. If there are ;10 more characters left to transmit, the TDD does not immediately begin to transmit the new characters, but ' instead imposes a pause at 58. During the pause at step 5~, the remote TDD may start transmitting data. Thus, at step 60 the TDD senses whether data is being received. At step 60, the machine has paused during a data ~;i transmission. Accordingly, if data is being received, j~
~ , that represents an interrupt by the remote station.
Accordingly, the program proceeds at step 62 to provide an interruQt signal to the user. Nevertheless the device still receives the data from the remote device and stores the potential output characters, ~agagn ~t step 55, rather than ~ransmittiaag characters ont~ the transmission line.
a At step 60 if no data was being received the program can branch back to step S6 end transmit characters again. The result of all o~ these steps is the implementation of the two rules discussed above. steps of Figure 3 result from ;a follow~.ng the twro rules of simply not transmitting when data is being received and dls~ pausing after the ;, tran8missiOn of elTery N Character t0 permit the Yemote ,, ~0 Station t0 transmit.
Tg~u$, the pseudo-duplex TDD terminal constructed in accordance wiah tlae present inventa.on is fully capable of pseudo-dopier comanunication with a compatibl~ TDD. ~.t the game time, the terminal is capable of communication with conventional TDD's, which would simply ignore the brief pause during the character transmission time. In addition, the pseudo-duplex TDD is competent to handle ~,~~ interruptions, so if the pseudo-duplex TDD is ': communicating with a conventional TDD, and the vin g3iz~9a~ ~ ~ ~ 3 ~ 3 9 ~~vus~~voa~~~
_~5_ ' conventional TDD begins to transmit, there may be a brief loss of a few characters, but then during the appropriate ; transmission pause, the pseudo-duplex TDD will recognize that a transmission is being received, and inhibit further i character transmissions until the next pause. Thus' the device ~s compatible with existing TDD's in the communication network, and does not require any modifications or changes in operation to existing TDD's in order to be compatible with this new device. Users do not have to alter their habits to use the improved TDD yet will, appreciate th~ advantages it offers.
:, It is a further advantage of the present invention in that it can be implemented and upgraded to existing TDD's :, by software upgrade. As may be seen in.~'ig. 1, the hardware portions of the circuit have to do with the 's analog input and output. The detail transmission behavior of the device, including the tizniing of transmitted data bits, and th~ translation of characters into Baudot code, are all. handled under software control by the program for ~0 the micropr~cessorcontained in the ROi~. Thus, to retrofit ~1d TDD's w3.th the pseudo-duplex capability, all that needs t~ be replaced is the ROM in the older TDD.
With a replacement of ~ single integrated circuit, the older conr~enti~nal TDD can be given the capability of handling an int~rrupt and acquire the pseudo-duplex capability de~cri~~ed a.n the present invention.
~t is understood that the present invention is not limited to tl~e part3.cular embodiments illustrated herein, but embraces such modified forms thereof as come r,~ithin the scope of the following claims.
J~ The RttM is intended t~ contain the program which dictates the functional o~e~xation of the microprocessor 14. The RA~i a.s uta.lized as a holding place or stack for data coming into or out of the TDD. In some TDD's, the micreaprocess~r, the RhM and the ~~M are all combined in a ' al singae inte~ratedvcircuit, while in ~thers they are separa~t~ circuits.
:z:
~s an additional output, the microprocessor connects ' through analog circuitry 30 to one of three separate a outputs. The analog circuitry 30 is, most preferably, a y', modem. One output of the analog circuitry 30 could be a telephone direct connect circuitry 32 which connects the modem directly by hardwiring into the telephone network.
2~~.3~~9 ''WC' ~3/23946 P~1"/US93/~4753 -7_ A second possible output from the analog circuitry is i through an acoustic output circuit 34 intended to audibly connect through a speaker 38 to the microphone of a ! telephone handset. At 36 is indicated acoustic input i 5 circuitry connected to a microphone 40, which is intended to audibly couple to the speaker in a telephone handset.
The acoustic output speaker and the acoustic input microphone may be coneected through a so-called "acoustic coupler" to a conventional telephone handset. In any TDD, either the hardwired connection or the acoustic_connection is provided, and sometimes both. It is also envisioned ' that the telephone line need not be a physical link. A
TDD could be made to operate as a cordless phone or through a cellular telephone system rather than through a conventional telephone two-wire connection.
i Shown in Fib. 2 is a simplified schematic of how the input and outputs of tlhe analog circuitry would work. For data coming l.nt0 the terdtl~.nal, the aud.lble input from a 's microphone or t~Iephone line is translated into electronic comport~nts and then presented to an amglif~.er 42. The output of the aa~plifi:er is presented to two phase-1~ckedrloops 44. One of the phase locked-loops 44 is tuned to a frequency of 1800 Hertz, while the other i phase-locked-loop 44 is tuned to a frequency of 1400 Hertz. 1800 Hegtz and 1400 Hertz are the designated carrier fregu~ncies for st~r~dard B~udot communication. On the ~utput side of th~ circuitry, output signals are a presented tc~ ~a I,PF (low pass filters transaait wave shaping circuit 46: The ~utput of that circuit, consisting of , alternate 1400 and 1800 Hertz signals, is presented to an ky amplifier 48 which 3.~ hardwired to the speaker ar te7.eph~ne line.
In normal Haudot communications with existing TDD's, each TDI3 communicates at 45.5 baud in a simplex mode. Tn some countries, the protocol is the same but the speed is 50 baud. That is to say each TDD transmits a character on ;;
the line whenever a key is pressed at the TDD. As a result, in order to approximate the give-and-take of nara~a.l conversation, TDD users generally have to indicate P~TlUS93/0~8753 ,~.,.~
WCi 93J23946 ~ ~ ~ ~
.
to the other user when the user that has the floor is ending that particular communication. For example, it is q uite common convention in the United States to type the j letters "GA" as an abbreviation for "go ahead" at the end of a text string to indicate to the other user that it is i ' his or her turn to type. This procedure is awkward and not like normal. conversation. Also, occasionally users wish to interrupt and, regardless of the constraints of i their machine, do attempt to type keys inta their machine 1 10 while receiving data. Such attempts to interrupt are typically not successful since the station transmitting data does not monitor the line for incoming data.
The TDD of the present invention is canstrained not to even attempt truly simultaneous communication. The v 15 imgroved TDD described here is simply programmed not to ,i transmit data when data is being recea:ved. This concept is directly opposite to the conv~nta.onal operation of TDD~s, but is effective if utilized as described here. It is a relatively si~tple matter that, when the 24 micro rocessor senses that a ke has been y pressed during data reception and which is int~nd~d to ultimately transmit a character t~ the rem~te station, for the microprocessor first t~ best whether analog data is being received; If data is being received, the microprocessor 25 is constbained by the software not to iz~mediat~I.y output he character onto the transmit line but, instead, to store the a 3 ppr~ riate characgers which have been entered by th~ user into the RAM. Typed characters are also stored in a queue or stack dur~.ng all ti.~nes of data 3a r~ceptio~a: The u~er~ may continue to type, end the ctaarac~ers are ea~tered by the keyboard, and are placed ante the ~ ua~tii such time as c~mmunication from the r,ea~note station h~~ ceased.
; When it is ta.m~ for the station a:n accordance with , 35 the present invention to transmit, the improved TDD
w, transmits characters either directly from its keyboard or , from the buffer composed of the RAM, out through the transmission line. The pseudo-duplex capable TDD of this invention will, however, pause periodically during the V'/P 3/23946 ~ ~ ~ ~ ~ ~ ~ P'~G'1°/US93104753 transmit data stream. The device is programmed to pause after the transmission of a pre-determined number of characters. The purpose of the pause is far the terminal to test during the pause whether input data is being received. In other words, the pause serves as an interrupt window for the other communicating machine.
Since the device is constrained not to transmit when receiving, if, during a pause, the other remote machine ; begins transmitting the local terminal will cease , transmission. In this way, most of the situations ira r;
which the two terminals would simultaneously transmit data are avoided. It is still possible occasionally for '~s simultaneous data transmissions to occur, when both stations simultaneously transmit data onto the line, but ,,'~ 15 these situations will be quite rare.
The number of characters which are transmitted by the . TDD in accordance with the present invention before a .,, pause is suDa~~ct to some variatian between two extremes.
fat one extreme, it is possible to present a pause on the transmission line .after the transmission of every single character. file this choice minimises the number of pot~r~tial data collisi~ns on the telephone ~.ine, it also ,>~ slows down the transmission when conducted at ordinary ~~a Baud~t transmission rates: Sinee Baudot operates 2S relatively slow in any event, ie: at 45.5 Baud, which appr~ximates 6 characters per second, adding an extra bit time ' or ~tw~ tc~ w~~r character might perceptively slow ~pwn tl~ae tscansm3.s~i~n by the terminal. At, its upper liait3.t, i.t is clearly possible to ~ impose such a pause every 72 cl~~act~rs, since the normal constraints of con~rent~.~nal Baudot cnmmu~nication protocols require that a carriage zetu~n end line feed be implemented every 72 characters folloured by a pause, originally imposed to allow for a mechanical TDD systems which must mechanically return the printing head. Thus there is an automatic pause time traditionally included in. Baudot/weitbrecht ' protocol at least every 72 characters within the data stream, by convention. In its preferred embodiment, it is ;~, :v? anticipated that the number of characters which will be WO 93/2394b p~/U593/04753 ~
1~SJJ
~~
.
transmitted in between pauses would be between 1 and '72, and most preferably between ~, and 10. Actual empiri_~al testing of terminals on a number of communication lines is necessary to determine which is the exact and optimum S number of characters to be transmitted between pauses.
The length of the pause after the packet of characters should be sufficient so as to permit settling of the communication line, a time period sufficient for the other terminal to commence data transmission, and a time period sufficient for the pausing station ~.o sense that data is being transmitted to it over the telephone line. These times can be varied over a wide range depending on the quality of the telephone netraork and the timing constraints of the hardware in the TDD. The normal bit time of conventional Baudot communication is aPProximately 22 milla.seconds. After transmitting Baudot tones, it can typically take some telephone lanes some ti.ane period for echoes, transients, and other chatter introduced on the line by previous communication signals to fade. In most modern t~lephon~ systems, a time period of five to fifty milliseconds is needed to permit such settling: A TDD in the accordance with the present inventaon pauses for ~ time period divided into two portions. The first portion is a pause for a sufficient time period,'su~la as l0 millisecond, to permit the t telephony line to settle. The second pause is for a suffici~nt tim~ pexi~d, such a~, 1~ to 44 mil~.is~oonds, a ~hidh is sufficient tigne for the transmitting teraninal to 3.nitiate tran~~issi~n and for th~ transmission to be sensed by the pausing ~t~~ion. An interrupt-competent and pseudo~duglex TDD constructed in accordance with the resent invention.will therefore often have to buffer data being typed a.n by the user , -: Duri.r~g time periods in which the user is typang at the keyboard, but the term~.nal is constrained fro$n transmitts.ng characters due to the receipt of characters from the remote terminal, the data characters being entered by the user would be stored in the random access memory in a stack or queue. Then, during th,e station's next interval for transmission, it P~1'/ x"1593104'753 Wr' X3/23946 ~11_ would transmit characters on a first-come first-serve basis out of the queue onto the transmission line.
This system is capable of operating either in conventional Baudot/Weitbrecht or in a newly designed enhanced ~audot communication grotocol. Neverthel,~ss, it is an advantage of the operation of this machine that it is capable of operating also with conventional TDD's, without any alteration to the conventional machines. Tf the TDD of the present invention is communicating with an otherwise conventional remote TDD, the remote terminal could occasionally lose characters if keys are pressed while ft is receiving. The pseudo-duplex TDD will tend to drop fewer characters since it cannot transmat~when the remote terminal is transmitting. In addition, any such losses at the remote terminal are minimized, since the TDD
in accordance with the present invention creates a pause at predetermined intervals, and when the first of those intervals occurs, the pseudo-duplex TDD will stop transnutting. Thereafter, the pseudo~duplex TDD will be able to receive whatever information is being transmitted by the stat3.on with Tahich it is communicating. Clearly the fewer the nuz~ber of characters transmitted between pauses, the fewer th'e number of characters which might be lost.
.As an o~ti~r~, .it may also be appropriate to include an interrupt ~igaaal in the TDD of the present invention.
If such an interrupt sign is implemented, the m~.cr~p~c~cess~r ~aauld as usual, monitor the input line during times it is not transmitting data to test for ~0 signals. The TDD would thus detect any data signal received during the periodic gauser even if the terminal still ~iad draracters to transmit. The microprocessor would then visually s~.gn~1 to the user fret an interrupt is be~.ng initiated by tre remote station. The visual interrupt sagnal c~uld consist of the word '°3.nterrupt" on the display, could consist of the display of a specially designated character not in the normal Baudot character set, such:as an asterisk or could consist of any characteristid character, ward or pattern designated for PC: t'/tJS93/U47S3 V1'~ 93/23946 ° f"""';
' -12-this purpose. Another alternative is to split the display into two sets (input and recoived characters) and the, user can be informed of the interrupt by noticing the split display. Then the user may cease typing on the keyboard, S to germit the transmission from the remote statiori"to be , .
y received by the terminal and displayed appropriately.
In the event that two interrupt-competent TDD's in y accordance with the present invention are communicating, missing transmitted data becomes an extremely unlikely vJ
~.0 event. In normal communication, when either one of the ';
two terminals is transmitting, the other terminal is c onstrained not to transmit. Then, since each station i when transmitting is constrained to step after a certain number of characters and present a pause, during that 15 pause the other station will gain control of the :n, communication line. Then t3~at station will transmit until ;: its turn to peas~. For example, if the persons at ;
stations A and B are both t~rping at the same time, one of PJ
the two TDD's at each station will initially gain control 20 ~f the comrauna.cation l9.ne, end transmit the predetermined numher ~rf charact~~rs. ~~~sume, for purposes of this example, that the number ~f transmitted characters is seven. Station A would transmit sbven characters to Station B, and Station ~ would be constrained not to 25 transmit during that interval. At the end of the would transmission of tie s~v~nth character, Station , peas~ and Station B ~rould ~eiz~ control ref the com~una.cata.on line and then communicate seven characters t~ Stat.l.on ~e. after that tame period, Station B would 30 pause; and Station ~ w~uld resume control ~f the com~unicati~n lines. In other words, each station would separately transmit tO the Other a burst of characters ' ,during alternate im~ periods. In this way, it would ~,f appear to the'us~ers as if a full duplex communication were 35 occurring. This form of communication is referred to here as gseudo-duplex, since the actual technical communications over the telephone line is in simplex, i.e.
with only one station able to communicate at an instant, yt s'i'r .s.: a~ "~ .,.,.
r~'~.~. ,.r~~::k, .....:..d:~~.w...e......etdre . ..... .. ,...:~a< ..
"y.:rr:o...ar.r.
..,..,N.,. ,...,.._:.i*.... ..,....._..m...... ..u...,o....1;1.*::e~.;..*i~%' Wt' ~3/23946 ~ ~ ~ ~ ~ ~ ~ P~.'1'/US93/04753 _~,3_ while the appearance to the users is of duplex, or two-way, communication.
Obviously, if a station is alternately both transmitting and receiving data in groups of small. numbers of characters, some provision must be made to make the display appropriate and readable to a user. At least two options are possible. One option is simply to have the user only see the information received from the foreign station. The other,~~a more preferable option, is to split the screen of the display on the terminal. This'split can be either vertical far one-line displays or horizontal if there is a two line or larger display. One portion of the split screen would be reserved for the characters being transmitted by the terminal and other portion of the split I5 screen ~~~uld display the characters being received from the remade terminal. Such split-screen operation is i entirely within the capability of the microprocessor to effectuate, the screen display being under software control in any event.
j Sh~wn in Figur~ 3 is ~ flow-chart representation of the workings of the te~m~.nal o~ Figures 1 and 2 operating in accordanc~ with the present invea~tion. At step 50, the microprocessor monitors the ~Ceyboard and the incoming telephony line for data: This step is perfox~ned in the normal fashion by which TDD°s perform these functions.
When a user p~ces~es a key the key selected by the user rep~esents'data which is accepted from the keyboard at method step 52: Most con~rentional prior TDD°s would immediately txans~a~a the character to the telephone li:ze.
In~t~ad the pseudo-duplex TDD first checks to ensure that no data is being received ~n the teie~hone line. If data i~ being received' he program branches and cantinues to receive the input data and buffer the output data until the incoming character stream ceases. This step is indicated at~55. Once the received data is stopped, the program may proceed back through the step of detecting whether data is being received at step 54. Once the situation arises where no data is being received, the program then pr~ceeds to step 56 where it transmits N
WO 93123946 PCI"1US93/04753 .~,..~
~~~~~c~l~
_24-characters of data from the keyboard. In this instance .Y
the letter I~ represents the numbers of letters in the, '. character packet which is transmitted by the pseudo-duplex a .
v TDD. As stated, the number N can be between 1 and ~2 and is preferably between 3 and 10. After the characters :.
packet has been transmitted, the program then determines 'd whether or not there are characters left to transmit. If ' all the characters have been transmitted the program can ,; return to its monitoring state at step 50. If there are ;10 more characters left to transmit, the TDD does not immediately begin to transmit the new characters, but ' instead imposes a pause at 58. During the pause at step 5~, the remote TDD may start transmitting data. Thus, at step 60 the TDD senses whether data is being received. At step 60, the machine has paused during a data ~;i transmission. Accordingly, if data is being received, j~
~ , that represents an interrupt by the remote station.
Accordingly, the program proceeds at step 62 to provide an interruQt signal to the user. Nevertheless the device still receives the data from the remote device and stores the potential output characters, ~agagn ~t step 55, rather than ~ransmittiaag characters ont~ the transmission line.
a At step 60 if no data was being received the program can branch back to step S6 end transmit characters again. The result of all o~ these steps is the implementation of the two rules discussed above. steps of Figure 3 result from ;a follow~.ng the twro rules of simply not transmitting when data is being received and dls~ pausing after the ;, tran8missiOn of elTery N Character t0 permit the Yemote ,, ~0 Station t0 transmit.
Tg~u$, the pseudo-duplex TDD terminal constructed in accordance wiah tlae present inventa.on is fully capable of pseudo-dopier comanunication with a compatibl~ TDD. ~.t the game time, the terminal is capable of communication with conventional TDD's, which would simply ignore the brief pause during the character transmission time. In addition, the pseudo-duplex TDD is competent to handle ~,~~ interruptions, so if the pseudo-duplex TDD is ': communicating with a conventional TDD, and the vin g3iz~9a~ ~ ~ ~ 3 ~ 3 9 ~~vus~~voa~~~
_~5_ ' conventional TDD begins to transmit, there may be a brief loss of a few characters, but then during the appropriate ; transmission pause, the pseudo-duplex TDD will recognize that a transmission is being received, and inhibit further i character transmissions until the next pause. Thus' the device ~s compatible with existing TDD's in the communication network, and does not require any modifications or changes in operation to existing TDD's in order to be compatible with this new device. Users do not have to alter their habits to use the improved TDD yet will, appreciate th~ advantages it offers.
:, It is a further advantage of the present invention in that it can be implemented and upgraded to existing TDD's :, by software upgrade. As may be seen in.~'ig. 1, the hardware portions of the circuit have to do with the 's analog input and output. The detail transmission behavior of the device, including the tizniing of transmitted data bits, and th~ translation of characters into Baudot code, are all. handled under software control by the program for ~0 the micropr~cessorcontained in the ROi~. Thus, to retrofit ~1d TDD's w3.th the pseudo-duplex capability, all that needs t~ be replaced is the ROM in the older TDD.
With a replacement of ~ single integrated circuit, the older conr~enti~nal TDD can be given the capability of handling an int~rrupt and acquire the pseudo-duplex capability de~cri~~ed a.n the present invention.
~t is understood that the present invention is not limited to tl~e part3.cular embodiments illustrated herein, but embraces such modified forms thereof as come r,~ithin the scope of the following claims.
Claims (23)
1. A telecommunication device for the deaf for communication over an analog telephone line, the device comprising a source of input data characters to be transmitted;
a destination for received data characters;
a microprocessor connected to accept input data characters from the input source and to deliver data characters to the destination;
an analog input circuit adapted to being connected to the telephone line so as to be responsive to the reception of Baudot tones over the telephone line and also connected to the microprocessor so as to provide a digital input to the microprocessor of the data received over the telephone line;
an analog output line adapted to being connected to the telephone line so as to be capable of presenting Baudot tones over the telephone line and also connected to receive data from the microprocessor and transmit Baudot tone encoding such date over the telephone line; and a memory device connected to the microprocessor containing the program code for operation of the microprocessor to control operation of the telecommunications device to generally (i) receive data entered from the input source; (ii) present entered data from the input source on the analog output line, (iii) receive input data from the analog input line and (iv) deliver data received on the input analog line to the destinations the program code further constraining the microprocessor to operate in accordance with the following rules: (i) if Baudot toned are being received on the input circuit, to not present output Baudot tones on the telephone line through, the analog output line; and (ii) during transmission, to pause after a preselected number of data characters transmitted and to test during that pause for the receipt of transmissions over the analog input circuit.
a destination for received data characters;
a microprocessor connected to accept input data characters from the input source and to deliver data characters to the destination;
an analog input circuit adapted to being connected to the telephone line so as to be responsive to the reception of Baudot tones over the telephone line and also connected to the microprocessor so as to provide a digital input to the microprocessor of the data received over the telephone line;
an analog output line adapted to being connected to the telephone line so as to be capable of presenting Baudot tones over the telephone line and also connected to receive data from the microprocessor and transmit Baudot tone encoding such date over the telephone line; and a memory device connected to the microprocessor containing the program code for operation of the microprocessor to control operation of the telecommunications device to generally (i) receive data entered from the input source; (ii) present entered data from the input source on the analog output line, (iii) receive input data from the analog input line and (iv) deliver data received on the input analog line to the destinations the program code further constraining the microprocessor to operate in accordance with the following rules: (i) if Baudot toned are being received on the input circuit, to not present output Baudot tones on the telephone line through, the analog output line; and (ii) during transmission, to pause after a preselected number of data characters transmitted and to test during that pause for the receipt of transmissions over the analog input circuit.
2. A telecommunication device for the deaf as claimed in claim 1 further comprising a visual interrupt signal which is actuated by the microprocessor when transmissions are received during the transmission pause.
3. A telecommunication device for the deaf as claimed in claim 1 wherein the pause includes two time periods, the first time period being of sufficient length for the telephone line to settle and the second time period being of sufficient length so that a remote telecommunications device could begin transmission and the transmission could be detected.
4. A telecommunication device for the deaf as claimed in claim 3 wherein the pause is for a time period of between five milliseconds and two seconds, with a first portion of the pause between a delay for the telephone line to settle and a second portion of the pause being the time period of testing for the receipt of transmissions.
5. A telecommunication device for the deaf as claimed in Claim 4 wherein the pause is between ten and two hundred milliseconds.
6. A telecommunication device for the deaf as claimed in claim 1 wherein the preselected number of data characters is between one and seventy-two.
7. A telecommunication device for the deaf as claimed in claim 1 wherein the preselected number of data characters is between one and ten.
8. A telecommunication device for the deaf as claimed in claim 1 wherein the input source is a manually operable keyboard.
9. A telecommunication device for the deaf as claimed in Claim 1 wherein the destination is a visually readable display.
10. A method of operating a telecommunication device for the deaf including a keyboard, a display, a microprocessor connected to receive data from the keyboard and present data to the display, input and output analog circuits to connect the microprocessor to a telephone line, and a memory circuit to comprising the steps of (a) receiving from the keyboard data from a user;
(b) transmitting the data received from the user onto the telephone line only when no input data, is being received from the telephone line;
(c) when transmitting data onto the telephone line, pausing for at least one bit time after a preselected number of characters and testing for the presence of input data on the telephone line; and (d) displaying on the display both the input and the output data.
(b) transmitting the data received from the user onto the telephone line only when no input data, is being received from the telephone line;
(c) when transmitting data onto the telephone line, pausing for at least one bit time after a preselected number of characters and testing for the presence of input data on the telephone line; and (d) displaying on the display both the input and the output data.
11. A method as claimed in claim 10 wherein in step (c), the pause includes two time periods, the first time period being of sufficient length for the telephone line to settle and the second time period being of sufficient length so that a remote telecommunications device can begin transmission and the transmission can be detected.
12. A method as claimed in claim 10 wherein in step (c), the pause is for a time period of between five and fifty milliseconds.
13. A method as claimed in claim 10 further comprising the step of visually signalling the user if data is received during the pause of step (c).
14. A telecommunication device for the deaf comprising a source of input data characters to be transmitted;
a destination for received data characters;
a microprocessor connected to accept input data characters from the input source and to deliver data characters to the destination;
an analog input circuit adapted to being connected to a telephone line so as to be responsive to the reception of Baudot tones over the telephone line and also connected to the microprocessor so as to provide a digital input to the microprocessor of the data received over the telephone line;
an analog output line adapted to being connected to the telephone line so as to be capable of presenting Baudot tones over the telephone line and also connected to receive data from the microprocessor and transmit Baudot tones encoding such data over the telephone line; and a memory device connected to the microprocessor containing the program code for operation of the microprocessor to control operation of the telecommunications device to generally (i) receive data entered from the input source, (ii) present entered data from the input source on the analog output line, (iii) receive input data from the analog input line and (iv) deliver data from the analog input circuit to the destination; the program code further constraining the microprocessor to not present output Baudot tones on the telephone line through the analog output line whenever input Baudot tones are being received on the input analog line.
a destination for received data characters;
a microprocessor connected to accept input data characters from the input source and to deliver data characters to the destination;
an analog input circuit adapted to being connected to a telephone line so as to be responsive to the reception of Baudot tones over the telephone line and also connected to the microprocessor so as to provide a digital input to the microprocessor of the data received over the telephone line;
an analog output line adapted to being connected to the telephone line so as to be capable of presenting Baudot tones over the telephone line and also connected to receive data from the microprocessor and transmit Baudot tones encoding such data over the telephone line; and a memory device connected to the microprocessor containing the program code for operation of the microprocessor to control operation of the telecommunications device to generally (i) receive data entered from the input source, (ii) present entered data from the input source on the analog output line, (iii) receive input data from the analog input line and (iv) deliver data from the analog input circuit to the destination; the program code further constraining the microprocessor to not present output Baudot tones on the telephone line through the analog output line whenever input Baudot tones are being received on the input analog line.
15. A telecommunication device for the deaf as claimed in claim 14 wherein the input source is a keyboard.
16. A telecommunication device for the deaf as claimed in claim 14 wherein the destination is a visually readable display.
17. A telecommunication device for the deaf comprising a source of input characters to be transmitted;
a destination for received characters;
a microprocessor connected to accept input data characters from the input source and to deliver received data characters to the destination;
an analog input circuit adapted to being connected to a telephone line so as to be responsive to the reception of Baudot tones over the telephone line and also connected to the microprocessor so as to provide a digital input to the microprocessor of the data received over the telephone line;
an analog output line adapted to being connected to the telephone line so as to be capable of presenting Baudot tones over the telephone line and also connected to receive data from the microprocessor and transmit Baudot tones encoding such data over the telephone line; and a memory device connected to the microprocessor containing the program code for operation of the microprocessor to control operation of the telecommunications device to generally (i) receive data entered from the input source, (ii) present entered data from the input source on the analog output line, (iii) receive data from the analog input line, and (iv) deliver received data from the input analog line and deliver the received date to the destination; the program code further constraining, during transmission, to pause after a preselected number of data characters transmitted and to test during that pause for the receipt of transmissions over the analog input circuit.
a destination for received characters;
a microprocessor connected to accept input data characters from the input source and to deliver received data characters to the destination;
an analog input circuit adapted to being connected to a telephone line so as to be responsive to the reception of Baudot tones over the telephone line and also connected to the microprocessor so as to provide a digital input to the microprocessor of the data received over the telephone line;
an analog output line adapted to being connected to the telephone line so as to be capable of presenting Baudot tones over the telephone line and also connected to receive data from the microprocessor and transmit Baudot tones encoding such data over the telephone line; and a memory device connected to the microprocessor containing the program code for operation of the microprocessor to control operation of the telecommunications device to generally (i) receive data entered from the input source, (ii) present entered data from the input source on the analog output line, (iii) receive data from the analog input line, and (iv) deliver received data from the input analog line and deliver the received date to the destination; the program code further constraining, during transmission, to pause after a preselected number of data characters transmitted and to test during that pause for the receipt of transmissions over the analog input circuit.
18. A telecommunication device for the deaf as claimed in claim 17 wherein the input source is a keyboard.
19. A telecommunication device for the deaf as claimed in claim 17 wherein the destination is a visually readable display.
20. A telecommunication device for the deaf comprising a keyboard;
a visually readable display;
a microprocessor connected to accept input data characters from the keyboard and to present data characters on the display;
an analog input circuit adapted to being connected to a telephone line so as to be responsive to the reception of Baudot tones over the telephone line and also connected to the microprocessor so as to provide a digital input to the microprocessor of the data received over the telephone line;
an analog output line adapted to being connected to the telephone line so as to be capable of presenting Baudot tones over the telephone line and also connected to receive data from the microprocessor and transmit Baudot tones encoding such data over the telephone line; and a memory device connected to the microprocessor containing the program code for operation of the microprocessor to control operation of the telecommunications device to generally (i) receive data entered from the keyboard, (ii) present entered data from the keyboard on the analog output line, (iii) receive input data from the analog input line and (iv) display data from both the keyboard and the input analog line on the display; the program code further constraining the microprocessor to operate in accordance with the following rules: (i) if Baudot tones are being received on the input circuit, to not present output Baudot tones on the telephone line through the analog output line; and (ii) during transmission, to pause after a preselected number of data characters transmitted and to test during that pause for the receipt of transmissions over the analog input circuit, the microprocessor also programmed to present on the visually readable display both the characters being transmitted and the characters beings received in separate portions of the display.
a visually readable display;
a microprocessor connected to accept input data characters from the keyboard and to present data characters on the display;
an analog input circuit adapted to being connected to a telephone line so as to be responsive to the reception of Baudot tones over the telephone line and also connected to the microprocessor so as to provide a digital input to the microprocessor of the data received over the telephone line;
an analog output line adapted to being connected to the telephone line so as to be capable of presenting Baudot tones over the telephone line and also connected to receive data from the microprocessor and transmit Baudot tones encoding such data over the telephone line; and a memory device connected to the microprocessor containing the program code for operation of the microprocessor to control operation of the telecommunications device to generally (i) receive data entered from the keyboard, (ii) present entered data from the keyboard on the analog output line, (iii) receive input data from the analog input line and (iv) display data from both the keyboard and the input analog line on the display; the program code further constraining the microprocessor to operate in accordance with the following rules: (i) if Baudot tones are being received on the input circuit, to not present output Baudot tones on the telephone line through the analog output line; and (ii) during transmission, to pause after a preselected number of data characters transmitted and to test during that pause for the receipt of transmissions over the analog input circuit, the microprocessor also programmed to present on the visually readable display both the characters being transmitted and the characters beings received in separate portions of the display.
21. A telecommunication device for the deaf comprising a keyboard;
a visually readable display a microprocessor connected to accept input data characters from the keyboard and to present data characters on the display;
an analog input circuit adapted to being connected to a telephone line so as to be responsive to the reception of Baudot tones over the telephone line and also connected to the microprocessor so as to provide a digital input to the microprocessor of the data received over the telephone line;
an analog output line adapted to being connected to the telephone line so as to be capable of presenting Baudot tones over the telephone line and also connected to receive data frog the microprocessor and transmit Baudot tones encoding such data over the telephone line; and a memoir device connected to the microprocessor containing the program code for operation of the microprocessor to control operation of the telecommunications device to generally (i) receive data entered from the keyboard, (ii) present entered data from the keyboard on the analog output line, (iii) receive input data from the analog input line and (iv) display data from both the keyboard and the input analog line on the display; the program code further constraining the microprocessor to operate in accordance with the following rules: (i) if Baudot tones are being received on the input circuit, to not present output Baudot tones on the telephone line through the analog output line; (ii) during transmission, to pause after a preselected number of data characters transmitted and to test during that pause for the receipt of transmissions over the analog input circuit; and (iii) to provide a visual output to the user indicating interrupt when data is received during the time period of a pause.
a visually readable display a microprocessor connected to accept input data characters from the keyboard and to present data characters on the display;
an analog input circuit adapted to being connected to a telephone line so as to be responsive to the reception of Baudot tones over the telephone line and also connected to the microprocessor so as to provide a digital input to the microprocessor of the data received over the telephone line;
an analog output line adapted to being connected to the telephone line so as to be capable of presenting Baudot tones over the telephone line and also connected to receive data frog the microprocessor and transmit Baudot tones encoding such data over the telephone line; and a memoir device connected to the microprocessor containing the program code for operation of the microprocessor to control operation of the telecommunications device to generally (i) receive data entered from the keyboard, (ii) present entered data from the keyboard on the analog output line, (iii) receive input data from the analog input line and (iv) display data from both the keyboard and the input analog line on the display; the program code further constraining the microprocessor to operate in accordance with the following rules: (i) if Baudot tones are being received on the input circuit, to not present output Baudot tones on the telephone line through the analog output line; (ii) during transmission, to pause after a preselected number of data characters transmitted and to test during that pause for the receipt of transmissions over the analog input circuit; and (iii) to provide a visual output to the user indicating interrupt when data is received during the time period of a pause.
22. A telecommunication device for the deaf as claimed in claim 21 wherein the visual indication is the presentation of the word "Interrupt" on the display.
23. A telecommunication device for the deaf as claimed in claim 21 wherein the visual indication is the presentation of a symbol not in the conventional Baudot character set on the display.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US886,642 | 1992-05-20 | ||
| US07/886,642 US5327479A (en) | 1992-05-20 | 1992-05-20 | Telecommunication device for the deaf with interrupt and pseudo-duplex capability |
| PCT/US1993/004753 WO1993023946A1 (en) | 1992-05-20 | 1993-05-19 | Telecommunication device for the deaf with interrupt and pseudo-duplex capability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2113839A1 CA2113839A1 (en) | 1993-11-25 |
| CA2113839C true CA2113839C (en) | 2003-03-18 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002113839A Expired - Fee Related CA2113839C (en) | 1992-05-20 | 1993-05-19 | Telecommunication device for the deaf with interrupt and pseudo-duplex capability |
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|---|---|
| US (1) | US5327479A (en) |
| EP (1) | EP0596078B1 (en) |
| AT (1) | ATE194899T1 (en) |
| AU (1) | AU4252393A (en) |
| CA (1) | CA2113839C (en) |
| DE (1) | DE69329053D1 (en) |
| WO (1) | WO1993023946A1 (en) |
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1992
- 1992-05-20 US US07/886,642 patent/US5327479A/en not_active Expired - Lifetime
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- 1993-05-19 AU AU42523/93A patent/AU4252393A/en not_active Abandoned
- 1993-05-19 AT AT93911360T patent/ATE194899T1/en active
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| EP0596078A1 (en) | 1994-05-11 |
| WO1993023946A1 (en) | 1993-11-25 |
| ATE194899T1 (en) | 2000-08-15 |
| AU4252393A (en) | 1993-12-13 |
| DE69329053D1 (en) | 2000-08-24 |
| US5327479A (en) | 1994-07-05 |
| EP0596078A4 (en) | 1995-05-17 |
| CA2113839A1 (en) | 1993-11-25 |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| MKLA | Lapsed |