tad@beaver.cs.washington.edu (Tad Cook) (05/25/90)
Where can I get signalling specifications for Terminal Devices for the Deaf? Does Bellcore or CCITT maintain these? Anyone know a good published source? I don't know much more than the fact that they use 45.45 baud Baudot code. If anyone wants to share some knowledge on this, call me at 800-824-9719 or 206-881-7000 between 7:30am-4pm PDT and ask for PAUL COOK. Tad Cook Seattle, WA Packet: KT7H @ N7HFZ.WA.USA.NA Phone: 206/527-4089 MCI Mail: 3288544 Telex: 6503288544 MCI UW USENET:...uw-beaver!sumax!amc-gw!ssc!tad or, tad@ssc.UUCP
PMW1@psuvm.psu.edu (Peter Weiss) (05/25/90)
Though not necessarily an answer to your question, the telecom-archives available FTP lcs.mit.edu has a file called deaf.communicate.on.tdd which contains pointers to other archive files. Peter M. Weiss | 31 Shields Bldg | University Park, PA USA 16802
KLH@nic.ddn.mil (Ken Harrenstien) (05/26/90)
[Posting a response is easier than calling those phone numbers.] I recall that the TDD manufacturers, under EIA auspices, were working on a standard to pin down all of the various TDD specifications. I don't know, however, if the EIA actually has a final result or not. My guess would be not, but it's certainly worth a try. I don't have a number handy but their office is in the other Washington (DC); try asking directory assistance for the Electronic Industries Association. Let us know if there's any news! Basically the old-style TDDs use 5-bit Baudot (American Communications set), 1.5 stop bit, 45.45 baud, with the Weitbrecht modem (U.S. Pat. No. 3,507,997 if you must know). The latter is half-duplex, 1400Hz mark, 1800Hz space, plus a somewhat undefined 100ms "holding tone" duration after last bit (otherwise the quiescent marking state would maintain a continuous 1400Hz tone). I don't know of any easily available published references. They do exist; we even wrote some of them as SRI project reports (you don't think I memorize patent numbers, do you?), but they're hard to get. That's why I suggest finding out if the EIA has come out with anything yet. Maybe Curtis Reid, another TDD-cognizant Telecom reader, knows of other alternatives. You can always send direct e-mail if you have specific technical questions. Ken