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Re: Echo PL tone




>
> Hi Drew and the list,
>
> I was just thinking about the QRM problem on the birds..
>
> Using mode U/v (the old mode B) instead of the V/u (mode J) might be a
> solution to the QRM problem, but coordination with other birds may be
> tricky?
>
> I've read that AO-10 used mode U/v with a 150 KHz passband! I'd imagine
that
> one FM bird downlink might be able to squeeze in with AO-10 gone...
>
> I would also imagine that the doppler effect would be less noticeable at
2m,
> so the bird would be easier for beginners to receive?
>

Absolutely. The downlink is trivial to receive on Mode B FM from LEO, and
interfering stations get dopplered out of the uplink quickly.  SO-35
(Sunsat) was the absolute loudest thing I've ever heard from space. I worked
it horizon to horizon on a 1/4 wave whip, with s9++ signals, and can't
recall ever hearing a pirate or out of segment ham working terrestrial.
Don't recall guys not hearing the downlink calling CQ either.

There may be other issues involving coordination and ops in other countries,
all of which I'd be interested in hearing.

I was told ECHO is mode J because Spacequest doesn't build VHF transmitters.
I guess thats as good a reason as any... Let's hope ECHO can run the
downlink at a high enough power that some of the problems we've had with
Mode J FM sats don't carry over to Echo.

73, Drew KO4MA


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