[RTTY] The magic of TU

[Kok Chen]

On Oct 3, 2013, at 1:18 PM, John wrote:

> What do you think leads to the signals I heard last weekend that have a short "chirp" at the beginning of each transmission?  (not RSID) There's a short space tone, followed by a short mark tone, followed by the Baudot message.  I kept track of some of the calls I heard with this distinctive signal if it would help.

Hah, I think you were listening to a 2Tone transmission.

I remember David G3YYD recently told me that he purposely started in Space state in 2Tone, hoping the other end will capture the first character better.  I am not convinced, but I have not tried simulating it myself, either.  Until then, I remain neutral about its usefulness.

The "usual" protocol is to start up with a short Mark condition, as if it is a long stop bit from a previous character.

73
Chen, W7AY