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A telecommunications device for the deaf (TDD) is an electronic device for text communication via a telephone line, used when one or more of the parties has hearing or speech difficulties. Other names for TDD include TTY (telephone typewriter or teletypewriter, although TTY is also a term used for teletypes in general), textphone (Common in Europe and the UK), and minicom (United Kingdom).
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About
The typical TDD is a device about the size of a small laptop computer with a QWERTY keyboard and small screen that uses LEDs or an LCD screen to display typed text electronically. In addition, TDDs commonly have a small spool of paper on which text is also printed — old versions of the device had only a printer and no screen. The text is transmitted live, via a telephone line, to a compatible device, i.e. one that uses a similar communication protocol. In certain countries there are systems in place so that a deaf person can communicate with a hearing person on an ordinary voice phone using a human relay operator. There are also "carry-over" services, enabling people who can hear but cannot speak ("hearing carry-over," a.k.a. "HCO"), or people who cannot hear but are able to speak ("voice carry-over," a.k.a. "VCO") to use the telephone.
History
The TTY concept was developed by James C. Marsters (born 1924; died 2009), a dentist and private airplane pilot who became deaf as an infant because of scarlet fever, and Robert Weitbrecht, a deaf physicist. In 1964, Marsters, Weitbrecht and Andrew Saks, an electrical engineer and grandson of the founder of the Saks Fifth Avenue department store chain, founded APCOM (Applied Communications Corp.), located in the San Francisco Bay area, to develop the acoustic coupler, or modem; their first product was named the PhoneType.[1][2][3] APCOM collected old teletype machines from the Department of Defense and junkyards. Couplers were cabled to TTYs enabling the Bell Telephone company standard "500 handset" to couple, or fit, into the rubber cups on the coupler, thus transmitting and receiving a unique set of tones generated by the different corresponding TTY keys. The entire configuration of teletype machine, acoustic coupler, and telephone set became known as the TTY. Weitbrecht invented the acoustic coupler modem in 1964. The actual mechanism for TTY communications was accomplished electromechanically through frequency shift keying (FSK) allowing only one-way (simplex) communication.
During the late 1960s, Paul Taylor combined Western Union teletype machines with modems to create the first telecommunications devices for the deaf, known as TDDs or TTYs (teletype machines). He distributed these early, non-portable devices to the homes of many in the Deaf community in St. Louis, Missouri. He worked with others to establish a local telephone wake-up service. In the early 1970s, these small successes in St. Louis evolved into the nation’s first local telephone relay system for the deaf.[4]
In 1973 the MCM (Manual Communications Module), which was the world's first electronic portable TDD (Telephone Device for the Deaf) allowing two-way telecommunications, premiered at the CAD (California Association of the Deaf) convention in Sacramento, California. The battery-powered MCM was invented and designed by Michael Cannon in conjunction with physicist Art Ogawa and deaf interpreter Kit Patrick Corson. It was manufactured by Michael Cannon's company, Micon Industries, and initially marketed by Kit Corson's company, Silent Communications. In order to be compatible with the existing TTY network, the MCM was designed around the five-bit Baudot code established by the older TTY machines instead of the ASCII code used by computers. The MCM was an instant success with the deaf community despite the drawback of a $599 cost. Within six months there were more MCMs in use by the deaf and hearing impaired than TTY machines. After a year Micon took over the marketing of the MCM and subsequently concluded a deal with Pacific Bell (who coined the term "TDD") to purchase MCMs and rent them to deaf telephone subscribers for $30 per month. After Micon formed an alliance with APCOM, Michael Cannon, Paul Conover (Micon), and Andrea Saks (APCOM) successfully petitioned the California Public Utilities Commission (CPUC) resulting in a tariff that paid for TDD devices to be distributed free of cost to deaf persons. Micon produced over 1,000 MCMs per month resulting in approximately 50,000 MCMs being disseminated into the deaf community. Before he left Micon in 1980, Michael Cannon developed several computer compatible variations of the MCM and a portable, battery operated printing TDD, but they were never as popular as the original MCM. Newer model TDDs could communicate with selectable codes that allow communications at a higher bit rate on those models similarly equipped. However, the lack of true computer interface functionality spelled the demise of the original TTY and its clones. During the mid-1970s other so-called portable telephone devices were being cloned by other companies, and this was the time period when the term "TDD" began being used largely by those outside the deaf community.
Marsters Award
In 2009, AT&T received the James C. Marsters Promotion Award from TDI, (formerly Telecommunications for the Deaf and Hard of Hearing, Inc.) for its efforts to increase accessibility to communication for people with disabilities.[5] The award holds some irony; it was AT&T that, in the 1960s, resisted efforts to implement TTY technology, claiming it would damage its communication equipment. In 1968, The Federal Communications Commission struck down AT&T's policy and forced it to offer TTY access to its network.[1][3]
Protocols
There are many different textphone standards. The original standard used by TDDs is the Baudot code implemented asynchronously at either 45.5 or 50 baud, 1 start bit, 5 data bits, and 1.5 stop bits. Baudot is a common protocol in the US. In Europe, different states use different protocols. For example, V.21 is found in the UK and several Scandinavian countries. Other protocols used for text telephony are EDT, DTMF, V.23, etc.
The TDD/TTY protocols are generally incompatible with standard Hayes-compatible modems. In 1994 the ITU approved the V.18 standard. V.18 is a dual standard. It is both an umbrella protocol that allows recognition and interoperability of some of the most commonly used textphone protocols, as well as offering a native V.18 mode, which is an ASCII full- or half-duplex modulation method.
Computers can, with appropriate software and modem, emulate a V.18 TDD. Some voice modems, coupled with appropriate software, can now be converted to TDD modems by using a software-based decoder for TDD tones. Same can be done with such software using a computer's soundcard, when coupled to the telephone line.
In the UK, a virtual V.18 network, called TextDirect, exists as part of the Public Switched Telephone Network, thereby offering interoperability between textphones using different protocols. The platform also offers additional functionality like call progress and status information in text and automatic invocation of a relay service for speech-to-text calls.
In addition to regular Baudot, the UltraTec company implements another protocol known as Enhanced TTY, which it calls "Turbo Code," in its products. Turbo Code has some advantages over Baudot protocols, such as a higher data rate, full ASCII compliance, and full-duplex capability. However, Turbo Code is proprietary, and UltraTec only gives its specifications to parties who are willing to license it.
Devices
In addition to TDD, there are a number of pieces of additional equipment that can be coupled to telephones to improve their utility. For those with hearing difficulties the telephone ring and conversation sound level can be amplified or pitch adjusted, ambient noise can also be filtered. The amplifier can be a simple addition or through an inductive coupler to interact with suitable hearing aids. The ring can also be supplemented with extension bells or a visual call indicator.
Etiquette
There are some etiquette rules that users of TDDs must be aware of. Because of the inability to detect when a person has finished speaking, the term "Go Ahead" (GA) is used.
Commonly used abbreviations:
| BRB | Be Right Back |
| CA | Communications assistant (another term for a relay operator) |
| CU | See You (be seeing you) |
| GA | Go Ahead |
| SK | Stop Keying |
| GA OR SK, GASK | Goodbye |
| SKSK | Now hanging up |
| HD | Hold (transmitted before a voice intercept message) |
| Q, QQ, QM | Question Mark (?) |
| PLS | Please |
| RO | Relay Operator |
| OIC | Oh, I See |
| OPR | Operator |
| NBR | Number |
| TMW | Tomorrow |
| THX | Thanks |
| WRU | Who are You? (or Where are You?) |
| XXXX | Xs are often used to indicate a typing error instead of backspacing |
Sample conversation
Caller A: HELLO JOHN, WHAT TIME WILL YOU BE COMING AROUND TODAY Q GA
Caller B: HI FRED, I WILL BE AROUND NOON GA
Caller A: OK, NO PROBLEM, DON'T FORGET TO BRING THE BOOKS AND THE WORK SO FAR GA
Caller B: WILL DO SK
Caller A: BYE BYE SKSK
SK is used to allow the users to say their farewells, while SKSK indicates an immediate call hang-up.
Sample conversation 2
Caller A HI, THIS IS JOHN, CAN I ASK WHO IS CALLING? GA
Caller B HI JOHN, ITS ME FRED, I AM WONDERING WHERE YOU ARE, ITS GETTING LATE TO GO OUT TO THE PUB GA
Caller A HI FRED, SORRY I DONT THINK I CAN GO. GA
Caller B WHY CANT YOU GO? GA
Caller A COS MY WIFE IS NOT FEELING WELL. AND I GOT NO BABYSITTER FOR MY KIDS! GA
Caller B AWWWW DAMN. I WANTED YOU THERE. AH WELL WHAT CAN I DO? GA
Caller A I KNOW.. I GOTTA GO. THE KIDS NEED ME. SEE YOU AROUND! BYE FOR NOW SK GA
Caller B OK NO WORRIES SEE YOU SOON! BYE BYE SK GA
Caller A SKSK (THE PARTY HAS HUNG UP)
Sample Text Relay call
Caller A TXD DIALING.. TXD RING... TXD OPERATOR CONNECTED.. EXPLAINING TEXT RELAY SERVICE. PLEASE WAIT.... HI THIS IS JOHN GA
Caller B HI JOHN ITS ME FRED. I AM WONDERING WHAT YOU ARE DOING TONIGHT? GA
Caller A HI FRED. I AM THINKING OF HAVING A POKER NIGHT AT MINE, WHAT DO YOU THINK? GA
Caller B GOOD IDEA, I'LL CALL A FEW MATES TO COME ROUND AND HAVE A GOOD GAME GA
Caller A OK SEE YOU AT 7PM. BYE BYE SK GA
Caller B OK SEE YOU AT 7PM BYE BYE SKSKSKSK GA
Caller A THANK YOU FOR USING TEXT RELAY SERVICE. GOODBYE
Note: TDDs use only capital letters.
Note: Text relay service used to be called typetalk (RNID) but have merged with the phone line using the dialling prefix 18001 (TDD) or the 18002 (voice relay) the emergency line is 18000 (TDD)
Relay
One of the most common uses for a TDD is to place calls to a Telecommunications Relay Service (TRS), which makes it possible for the deaf to successfully make phone calls to regular phone users.
The use of voice recognition systems is in limited use due to technical difficulties. However, a new development called the captioned telephone, now utilizes voice recognition to assist the human operators. Newer text based communication methods, such as short message service (SMS), Internet Relay Chat (IRC), and instant messaging have also been adopted by the deaf as an alternative or adjunct to TDD.
See also
Notes
- ^ a b His Ingenuity Helped the Deaf Tap the Power of Telephones, Remembrances, Wall Street Journal, August 21, 2009, p.A9
- ^ Gallaudet University, book excerpt
- ^ a b "James Marsters, Deaf Inventor, Dies at 85". New York Times. 2009-08-22. http://www.nytimes.com/2009/08/23/us/23marsters.html?hpw. Retrieved 2009-08-24. ]
- ^ Readmond, Kim. "Paul and Sally Taylor Background Sheet," Central Institute for the Deaf; Lang, Harry G. (2000). A phone of our own: the deaf insurrection against Ma Bell, p. 67.
- ^ Yahoo Canada Finance News, July 31, 2009, retrieved August 22, 2009
References
- Lang, Harry G. (2000). A Phone of Our Own : the Deaf Insurrection Against Ma Bell. Washington, D.C.: Gallaudet University Press. 10-ISBN 1-563-68090-4/13-ISBN 978-1-563-68090-8; OCLC 59576008
- Readmond, Kim. "Paul and Sally Taylor Background Sheet," Central Institute for the Deaf (St. Louis, Missouri).
- Strauss, Karen Peltz. (2006). A New Civil Right: Telecommunications Equality for Deaf and Hard of Hearing Americans. Washington, D.C.: Gallaudet University Press. 10-ISBN 1-563-68291-5/13-ISBN 978-1-563-68291-9; OCLC 62393257
External links
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