[GreenKeys] AMTOR/SITOR/NAVTXT Protocol

[Christian Gauger-Cosgrove]

Hi Tony!

On 7 December 2014 at 23:44, tony.podrasky <tony.podrasky at gmail.com> wrote:
> GM OMs;
>
> Now that WLO is transmitting in both ITA#2 and SITOR-B, I'd
> like to write a "C" program to decode the SITOR-B mode.
>
Pardon the "youth" speak but: SITOR be cool, yo.
Further "youth" speak: C be da shit, homie.


Now, being serious; SITOR modes are rather interesting I find, and
correct me if I'm wrong, but weren't the various
bastard-son-of-a-bitch PACTOR modes built off of SITOR/AMTOR? (Please
note, PACTOR is just fine when it's not being used by morons. It would
also be even more fine if it weren't locked up in patents/IP
copyright/"random crap I don't care about".)

Also as a person who does program in C, but isn't really great at it,
why choose C, of all languages?


> The research I have done tells me that it is transmitted
> at 100 Baud and uses 7-bit code.
>
> Is that 7-bit code synchronous - or is it using a STOP bit?
>
> I'm guessing that since a synchronous transmission over the
> air would be impractical, that they must have at least a
> single stop bit.
>
The characters are transmitted synchronously. The CCIR 476 character
set is an "N-of-M" type code (four bits of the seven are 1 the rest
are 0), and the transmitter sends a synchronization signal every
second.


> Does anyone know?
>
> Does anyone know where I can go to do more research?
>
The fldigi project, which is free and open-source, has a SITOR-B modem
(does TX and RX), go poke around the source to see what it holds.

Fldigi also does NAVTEX, which is just a specific format put on top of SITOR-B.


Cheers,
Christian

-- 
Christian M. Gauger-Cosgrove
STCKON08DS0
Contact information available upon request.