[GreenKeys] Teletype Devices for the Deaf (TDD)

[Don Robert House]

At 11:59 AM -0500 2/24/2003, Charles Ring, W3NU wrote:
>Gary Chatters wrote:


>  >
>>  The TTY system for the deaf (TDD) was developed by a deaf ham, W6NRM.  One
>>  of the primary considerations was making the modems cheap.  The TDD modems
>>  use a single tone OOK, not FSK.  That is about as simple as you can make
>>  it.
>>
>>  Gary
>>
>
>is this standard still in use now with the electronic TDD devices, and are the
>old machines/modems still compatible?
>

Charles,

My understanding is that they are still compatible with a 
disclaimer...  "NO SPECIAL CHARACTERS"  The modern TDD takes some 
liberty with ITA2 Baudot and makes some different codes for special 
characters.

Don
-- 
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Don Robert House
North American Data Communications Museum
URL: http://www.nadcomm.org
Computer Museum of America
URL: http://www.computer-museum.org