A Phone of Our Own: The Deaf Insurrection Against Ma Bell

3. Something Old, Something New

c-=-SOMETHING OLO, SOMETHING NEW The marriage ofthe older TTY to the new acoustic coupler was the crux of Weitbrecht's design for a visual telephone device. He planned to develop a coupler that would produce a different audio signal as each key on the teletypewriter was pressed. Typing a single letter on the keyboard would "modulate" the signal to be transmitted by adding information to it. A similar transmitter-receiver unit on the other end of the telephone line would "demodulate" the signal, converting the information to an electric pulse that would print the same letter on the receiver's TTY. The illQdulating-.&modulating (or "modem") device would have to be built and sold to each deaf person wishing to have a telephone. Weitbrecht faced several obstacles as he set out to develop the telephone modem. First, the telephone modem could not be connected directly to telephone company equipment. The telephone companies were strict about "foreign attachments." They were concerned that when a customer connected another device directly to the telephone lines, there might be electrical interference with the company's signals . AT&T's restrictions on direct connections frustrated Weitbrecht's attempt to find solutions. He knew that a direct connection to the phone line would reduce garble in the TTY messages. But anyone who attempted a direct connection ran the risk of having telephone services stopped. In an attempt to satisfy AT&T, Weitbrecht spent years conducting experiments with a modem that avoided a direct connection. Second, it was important that modem use not disable the telephone system in any way. Therefore, Weitbrecht designed a wooden cradle box on which to place the telephone handset. The cradle contained a miniature loudspeaker and an induction coil. The loudspeaker sent 30 SOMETHING OLD, SOMETHING NEW I 31 (Top Left) Robert H. Weitbrecht's design for the first TIY for deaf peopLe included an acoustic coupLer that converted audio tones received from the teLephone through a microphone in the (top right) cradLe to eLectric signals and produced typed messages on the teLeprinter. (Bottom) His schematic diagram for signaL paths between two TIY stations shows how the moduLator-demoduLator (modem) wouLd work. Courtesy of James C. Marsters. tones into the microphone (mouthpiece) of the telephone handset. The induction coil received a message by picking up the signal through the magnetic field generated by the telephone earpiece. With this use of a cradle in his design, Weitbrecht bypassed AT&T's objection to a direct connection to their telephone lines, thus ensuring that the modem would not disable the phone. Third, he had to keep the modem tone loudness to a minimum because AT&T had established restrictions on the volume ofthe audible tones that could be generated by modems. This obstacle presented a special problem. The lower the volume of the modem tone, the more garbled the message could become. To make matters more complicated , the volume levels established by AT&T were very hard for Weitbrecht to work with. 32 I SOMETHING OLD, SOMETHING NEW Fourth, Weitbrecht had to find a way to signal the deaf caller that the telephone at the receiving end was busy, ringing, or being answered. This was easily solved with a small indicator lamp that lit with the dial tone. Busy and ringing signals were distinguished by the length oftime the lamp remained lit. The scarcity of used TTYs presented a different kind of problem. Based on his amateur radio experience, Weitbrecht knew that telephone companies destroyed surplus teleprinters to prevent them from being used by people who would otherwise subscribe to company services . Yet these discarded machines could provide deafpeople with lowcost phone devices. Marsters purchased a new Model 32 ASR (Automatic Send-Receive) Teletype to assist Weitbrecht in the early trials. Marsters' willingness to pay the substantial sum of $600 in 1964 for a new trouble-free TTY was critical. With it, Weitbrecht could concentrate on the modem design and worry less about mechanical and electrical teletypewriter malfunctions. Still another problem was that the older TTYs spoke a language of their own: Baudot. This was a code developed for mechanized telegraphy in the nineteenth century by an officer in the French telegraph service. It is called a "five-level" code for transmitting and receiving messages because five "bits" of information are needed for each letter, figure, or other character being transmitted. Newer and faster "eight-level" machines use the American Standard Code for Information Interchange (ASCII), which has an extended set of characters.l...