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
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