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Re: PSK31 & SSTV AO-40



John NS1Z wrote:

Is there a technical reason to operate only above the beacon? What is wrong
with the lower part of the transponder? I realize that SSTV is not
considered digital but PSK surely is. I would think it would be better to
use the lower portion for the non-voice modes. Just check out the HF bands
for the problems that arise when voice and non-voice modes are intermixed.

Wayne W9AE replies:

There is a practical reason to stay above the beacon frequency.  That's
because virtually everybody operates above the beacon.  Regardless of the
mode, if you call CQ below the beacon your odds of getting a reply are much
lower than if you call CQ above the beacon.  Most AO40 users rarely (if
ever) tune below the beacon.

Another practical matter is that a rigid band plan isn't really necessary
until AO40 becomes crowded and QRM becomes a problem.  By it's very nature,
AO40 is less prone to accidental QRM than the HF bands because (ideally) all
AO40 users can hear everything.  There is no selective propagation.

I agree that it makes technical sense for digital operators to stay below
the beacon.  Feel free to start the trend yourself!  Be patient if nobody
answers you after the first 2,3, or 10 calls.  If it's any help, I will
pledge to tune below the beacon.  Maybe I'll even install WinPSK when I
return home (I've used DigiPan for terrestrial PSK-31).

With present operating habits, it should be obvious that all testing and
tuning (sweeping carriers, etc.) should be done below the beacon where you
are less likely to interfere with other users.

Wayne Estes W9AE
temporarily off the air in Beijing, China
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