Telecommunications device for the deaf
Encyclopedia
Teleprinter
A teleprinter is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the...
, an electronic device for text communication over a telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
line, that is designed for use by persons with hearing
Hearing impairment
-Definition:Deafness is the inability for the ear to interpret certain or all frequencies of sound.-Environmental Situations:Deafness can be caused by environmental situations such as noise, trauma, or other ear defections...
or speech difficulties
Speech disorder
Speech disorders or speech impediments are a type of communication disorders where 'normal' speech is disrupted. This can mean stuttering, lisps, etc. Someone who is unable to speak due to a speech disorder is considered mute.-Classification:...
. Other names for the device include teletypewriter, TTY
TTY
TTY may stand for:* Teleprinter or Teletypewriter or Teletype Printer, a typewriter paired with an electronic communication channel, used for telecommunications or as a computer terminal....
, textphone (common in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
), and minicom (United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
).
The typical TTD is a device about the size of a typewriter or laptop computer with a QWERTY
QWERTY
QWERTY is the most common modern-day keyboard layout. The name comes from the first six letters appearing in the topleft letter row of the keyboard, read left to right: Q-W-E-R-T-Y. The QWERTY design is based on a layout created for the Sholes and Glidden typewriter and sold to Remington in the...
keyboard
Computer keyboard
In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...
and small screen that uses LED
Light-emitting diode
A light-emitting diode is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting...
s or an LCD screen to display typed text electronically. In addition, TTDs 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.
Special telephone services have been developed to carry the TTD functionality even further. 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.
APCOM accoustic coupler or MODEM device
The TTD concept was developed by James C. MarstersJames C. Marsters
James Carlyle Marsters was a deaf orthodontist in Pasadena, California who in 1964 helped invent the first teletypewriter device capable of being used with telephone lines. The device made communication by telephone possible for the deaf...
(1924–2009), a dentist and private airplane pilot who became deaf as an infant because of scarlet fever
Scarlet fever
Scarlet fever is a disease caused by exotoxin released by Streptococcus pyogenes. Once a major cause of death, it is now effectively treated with antibiotics...
, and Robert Weitbrecht
Robert Weitbrecht
Robert Haig Weitbrecht was born in Orange, California in 1920. He was born deaf and his education was mainstream for the most part with the exception of acquiring some signing and lip-reading skills from a deaf school early on. He went on to earn a B.S. in Astronomy from the University of...
, a deaf physicist. In 1964, Marsters, Weitbrecht and Andrew Saks, an electrical engineer and grandson of the founder of the Saks Fifth Avenue
Saks Fifth Avenue
Saks Fifth Avenue is a luxury American specialty store owned and operated by Saks Fifth Avenue Enterprises , a subsidiary of Saks Incorporated. It competes in the high-end specialty store market in the Upper East Side of Manhattan, i.e. 'the 3 B's' Bergdorf, Barneys, Bloomingdale's and Lord & Taylor...
department store chain, founded APCOM (Applied Communications Corp.), located in the San Francisco Bay area, to develop the acoustic coupler
Acoustic coupler
In telecommunications, the term acoustic coupler has the following meanings:# An interface device for coupling electrical signals by acoustical means—usually into and out of a telephone instrument....
, or modem
Modem
A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...
; their first product was named the PhoneType. APCOM collected old teleprinter machines
Teleprinter
A teleprinter is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the...
from the Department of Defense
United States Department of Defense
The United States Department of Defense is the U.S...
and junkyards. Acoustic coupler
Acoustic coupler
In telecommunications, the term acoustic coupler has the following meanings:# An interface device for coupling electrical signals by acoustical means—usually into and out of a telephone instrument....
s were cabled to TTYs enabling the Bell Telephone Company
Bell Telephone Company
The Bell Telephone Company, a common law joint stock company, was organized in Boston, Massachusetts on July 9, 1877 by Alexander Graham Bell's father-in-law Gardiner Greene Hubbard, who also helped organize a sister company — the New England Telephone and Telegraph Company...
standard Model 500 telephone
Model 500 telephone
The Western Electric model 500 telephone series was the standard desk-style domestic telephone set issued by the Bell System in North America from late 1949 through the 1984 Bell System divestiture. Millions of model 500-series phones were produced and were present in almost every home in North...
to couple, or fit, into the rubber cups on the coupler, thus allowing the device to transmit and receive a unique set of tones generated by the different corresponding TTY keys. The entire configuration of teleprinter 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.
Paul Taylor TTY device
During the late 1960s, Paul TaylorPaul Taylor (engineer)
Paul Taylor is an American engineer, a pioneer in development of telecommunications devices for the deaf . He also enjoys a kind of celebrity status because of his central role in the award-winning documentary Hear and Now. The film by daughter Irene Taylor Brodsky chronicles the before and...
combined Western Union Teletype
Teletype Corporation
The Teletype Corporation, a part of American Telephone and Telegraph Company's Western Electric manufacturing arm since 1930, came into being in 1928 when the Morkrum-Kleinschmidt Company changed its name to the name of its trademark equipment...
machines with modems to create teletypewriters, known as TTYs. 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.
Mincon Industries MCM device
In 1973 the MCM (Manual Communications Module), which was the world's first electronic portable TTY allowing two-way telecommunications, premiered at the 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 codeBaudot code
The Baudot code, invented by Émile Baudot, is a character set predating EBCDIC and ASCII. It was the predecessor to the International Telegraph Alphabet No 2 , the teleprinter code in use until the advent of ASCII. Each character in the alphabet is represented by a series of bits, sent over a...
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 Hard of Hearing than TTY machines. After a year Micon took over the marketing of the MCM and subsequently concluded a deal with Pacific Bell
Pacific Bell
The Pacific Telephone and Telegraph Company was the name of the Bell System's telephone operations in California. It gained in size by acquiring smaller telephone companies along the Pacific coast, such as Sunset Telephone & Telegraph in 1917...
(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 (Mincon), Paul Conover (Micon), and Andrea Saks (APCOM) successfully petitioned the California Public Utilities Commission (CPUC) resulting in a tariff that paid for TTY 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 TTY, but they were never as popular as the original MCM. Newer model TTYs 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, Inc.Telecommunications for the Deaf, Inc.
Telecommunications for the Deaf and Hard of Hearing, Inc. is headquartered in Silver Spring, Maryland and was founded in 1968. Its original purpose was to promote widespread distribution of Telecommunications device for the deaf and publish a telephone directory of those that used TTY...
) for its efforts to increase accessibility to communication for people with disabilities. 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
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
struck down AT&T's policy and forced it to offer TTY access to its network.
Baudot code
The original standard used by TTYs is the Baudot codeBaudot code
The Baudot code, invented by Émile Baudot, is a character set predating EBCDIC and ASCII. It was the predecessor to the International Telegraph Alphabet No 2 , the teleprinter code in use until the advent of ASCII. Each character in the alphabet is represented by a series of bits, sent over a...
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.
Turbo Code
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 ASCIIASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
compliance, and full-duplex capability. However, Turbo Code is proprietary, and UltraTec only gives its specifications to parties who are willing to license it.
Other legacy protocols
Other protocols used for text telephony are European Deaf Telephone (EDT) and Dual-tone multi-frequency signaling (DTMF).The ITU V series recommendations are a collection of early modem standards approved by the ITU
Itu
Itu is an old and historic municipality in the state of São Paulo in Brazil. The population in 2009 was 157,384 and the area is 641.68 km². The elevation is 583 m. This place name comes from the Tupi language, meaning big waterfall. Itu is linked with the highway numbered the SP-75 and are flowed...
in 1988.
- ITU V.21 http://www.itu.int/rec/T-REC-V.21/recommendation.asp?lang=en&parent=T-REC-V.21-198811-I specifies 300 bits per second duplex mode.
- ITU V.23ITU V.23The V.23 standard was an early modem standard approved by the ITU in 1988. It specifies audio frequency-shift keying to encode and transfer data at a rate of 1200 bits per second, half-duplex at 1200 baud , for the forward data-transmission channel, and an optional 75 baud backward channel.* V.23...
http://www.itu.int/rec/T-REC-V/recommendation.asp?lang=en&parent=T-REC-V.23 specifies audio frequency-shift keying modulation to encode and transfer data at 600/1200 bits per second.
V.18
In 1994 the ITUInternational Telecommunication Union
The International Telecommunication Union is the specialized agency of the United Nations which is responsible for information and communication technologies...
approved the V.18 standardhttp://www.itu.int/rec/T-REC-V.18/en. 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
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
full- or half-duplex modulation method.
Computers can, with appropriate software and modem, emulate a V.18 TTY. Some voice modems, coupled with appropriate software, can now be converted to TTY modems by using a software-based decoder for TTY 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
Public switched telephone network
The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...
, 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.
Additional advances
As TDD's are increasingly considered legacyLegacy system
A legacy system is an old method, technology, computer system, or application program that continues to be used, typically because it still functions for the users' needs, even though newer technology or more efficient methods of performing a task are now available...
devices, with the emergence of modern technologies such as email
Email
Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...
, texting and instant messaging
Instant messaging
Instant Messaging is a form of real-time direct text-based chatting communication in push mode between two or more people using personal computers or other devices, along with shared clients. The user's text is conveyed over a network, such as the Internet...
, text from TDD are increasingly being sent over Text over IP gateways, or other real-time text
Real-time text
Real-time text is streaming text that is continuously transmitted as it is typed or otherwise composed. It allows conversational use of text, where people interactively converse with each other.-Use over instant messaging:...
protocols.
Other devices for hearing impaired
Etiquette
There are some etiquette rules that users of TTYs must be aware of. Because of the inability to detect when a person has finished speaking, the term "Go Ahead" (GA) is used to denote the end of a thought.| Acronym | |
|---|---|
| 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 (not an imperative to the other person but rather a description of what the keyer is doing, A. preventing the subsequent dead air Dead air Dead air is an unintended interruption in a radio broadcast during which no sound is transmitted.The term is most often used in cases where program material comes to an unexpected halt, either through operator error or for technical reasons, although it is also used in cases where a broadcaster... from confusing the recipient by letting the recipient know not to expect any more messages but also B. letting the recipient know that the keyer remains "listening" for any "goodbye"-type message) |
| SKSK | Now hanging up (used in reply to SK as confirmation that the replying keyer has nothing left to say and that both ends of the conversation [and, therefore, the conversation as a whole] are terminated) |
| GA OR SK, SKGA | Goodbye |
| Hold (transmitted before a voice intercept message Intercept message An intercept message is a telephone recording informing the caller that the call cannot be completed, for any of a number of reasons ranging from local congestion, to disconnection of the dialled phone, or network trouble along the route.... ) |
|
| 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 GACaller 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? GACaller 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 MY WIFE IS NOT FEELING WELL AND I HAVE NO BABYSITTER FOR MY KIDS! GA
Caller B AWWWW DARN. I WANTED YOU THERE. OH WELL WHAT CAN YOU DO ? GA
Caller A I KNOW.. I GOTTA GO. THE KIDS NEED ME. SEE YOU AROUND! BYE FOR NOW SK
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 GACaller 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: TTYs 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 (TTY) or the 18002 (voice relay) the emergency line is 18000 (TTY)
Relay
One of the most common uses for a TTY is to place calls to a Telecommunications Relay ServiceTelecommunications Relay Service
Telecommunications Relay Service, also known as TRS, Relay Service, or IP-Relay, or Web-based relay services, is an operator service that allows people who are Deaf, Hard-of-Hearing, Speech-Disabled, or DeafBlind to place calls to standard telephone users via a keyboard or assistive device...
(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. 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
Short message service
Short Message Service is a text messaging service component of phone, web, or mobile communication systems, using standardized communications protocols that allow the exchange of short text messages between fixed line or mobile phone devices...
(SMS), Internet Relay Chat
Internet Relay Chat
Internet Relay Chat is a protocol for real-time Internet text messaging or synchronous conferencing. It is mainly designed for group communication in discussion forums, called channels, but also allows one-to-one communication via private message as well as chat and data transfer, including file...
(IRC), and instant messaging
Instant messaging
Instant Messaging is a form of real-time direct text-based chatting communication in push mode between two or more people using personal computers or other devices, along with shared clients. The user's text is conveyed over a network, such as the Internet...
have also been adopted by the Deaf as an alternative or adjunct to TTY.
See also
- List of video telecommunication services and product brands
- Robert H. Weitbrecht
- Paul Taylor (engineer)Paul Taylor (engineer)Paul Taylor is an American engineer, a pioneer in development of telecommunications devices for the deaf . He also enjoys a kind of celebrity status because of his central role in the award-winning documentary Hear and Now. The film by daughter Irene Taylor Brodsky chronicles the before and...