[OZAPRS] Decoding HF APRS (Rob)

[Robert Bruninga]

>>> "Tony Hunt" <wavetel at bigpond.com> 07/08/06 5:11 AM >>>
>The old 170Hz shift originated with RTTY by these days 
>some RTTY activity seems to even be using 200Hz shift 
>so its all a bit confusing and more to the point all a bit painful.. 

Yes, we standardized AX.25 packet on HF at 200 Hz back in
1983 or so when we put up the first packet BBS on HF using 
a VIC-20 and Bell 103 modem which uses 200 Hz shift.  That
was pretty much the standard until some TNC MFR's began to take
shortcuts and to stay compatible with RTTY too, they just
put the single 170 Hz shift in to optimize for RTTY (weak signal)
and didnt care about optimization of packet..  

But good TNC's offer both.

Bob, WB4APR

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