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Re: FO-29





Brook Smith wrote:

> > William Erhardt wrote:
> >
> > Howdy Fm Montana - I was calling cq cw on FO-29 on the 23:30 UTC pass
> > at 145.950 up and 435.847 down when an FM signal came on freq for
> > about 1 minute - I moved up frequency and called again and the FM
> > followed me up about 10 kcs and transmiited again. Did anyone else
> > here this FM signal
> >
> > Bill KA7YAO
>
> Hi Bill,
>
> I have some thoughts about your posting.  The fact that the signal
> "followed" you is proof of "intentional" interference.  When I ask
> myself why anyone would do this, it required me to ponder my long
> term experience with the "FO" birds.

Bill, Brook, et al:

Brook's scenario, is very possible.  I have been in QSO with other ops at
times recently and all of a sudden, right on top of us someone began
calling CQ in CW.  As far as I know, nobody in our roundtable would
deliberately change to FM mode and intentionally QRM you.  First off, how
much of the FM signal would you hear with the tight filtering I suspect you
would use on CW?  If the QRM was intentional, a "smart" op would crank up
the power and send a continuous carrier to assault your hearing.  Using an
FM signal to buffet a transponder squatter would be analogous to fighting
off a mugger with a feather duster.

Instead, consider this scenario:

We have been hearing a great deal of QRM from what appears to be FM
repeater users in Central America.  I have myself flipped my receiver to FM
in an attempt to ID the offending signal.  If I then forgot to switch the
transceiver back into SSB mode, and transmitted, the result would be an
unintentional source of QRM from my FM signal.  Maybe if that is what
happened, and the op heard distortion in his downlink, they moved in the
pass band and found a loud signal, (you?) and tried transmitting again.
Hence, you would determine the FM signal was chasing you.  You must have
flipped to FM mode from your narrow linear mode in order to determine it
was an FM signal.  Did you get a call sign (Mike's hoping he doesn't say
kf4fdj :-) ),  and how long did the signal persist?  Were they calling CQ,
or was it a whistler, or moaner? (you've all done/heard that!)

My experience leads me to defend the satellite ops as the most courteous,
helpful, and motivated of the amateur lot.  I don't want to believe that
ANY regular op would intentionally QRM anybody else.  I have a gut feeling
that while the QRM was real, there is a rational and scientific
explanation, and the QRM was caused by an unaware op.

As far as transponder noise goes, I've heard the craziest noises from the
FO-29 transponder.  Sometimes it pops, moans, whistles, hums, zips, zaps,
without any terrestrial signal tickling the transponder.  It has by far the
noisiest transponder of the analog birds.  Maybe the bird was QRMing you as
a result of inter modulation or overload on it's own sensitive receiver.

Just some food for though.  Happy new year, and good DX!   73, Mike
kf4fdj@amsat.org


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