[GreenKeys] FSK shifts

[Richard Dillman]

On Sun, Aug 22, 2021 at 5:48 AM Duncan Brown <duncanancy at earthlink.net>
wrote:

I was surprised to learn that KPH is running 170Hz shift on RTTY and
> that is now the standard for commercial RTTY/SITOR/NAVTEX.
>

Greetings all.  We hope to resume testing on Saturday 9/4 on 12858.5 and
6324.5 starting at 1100 Pacific (1800Z) time with Baudot followed by SITOR
FEC.  TPO on both frequencies is 5kW using the original KPH Henry HF5000D
transmitters.  I hope that with longer notice more folks will have a chance
to listen.

Regarding 170Hz shift, this is defined by the FCC emission designator
300HF1B, the use of which goes back several decades to the introduction of
SITOR globally as a means of error correcting NBDP (Narrow Band Direct
Printing in FCC speak) for maritime communication.  Almost all coast
stations used this system as it provided an automated means for ships to
connect with the coast station and send and receive messages without
operator intervention.  While such use has almost completely disappeared,
the USCG and the coast guards of several other nations still use the FEC
(forward error correction) mode of SITOR for marine information broadcasts
on HF as well as MF for NAVTEX.  One can also still hear the channel
markers for stations like XSG, XSQ, TAH, etc., although it appears that
traffic is seldom passed.

Best Regards,

RD


Richard Dillman
Maritime Radio Historical Society
https://www.radiomarine.org
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