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[aprssig] New 9600 baud APRS satellite maybe

Robert Bruninga bruninga at usna.edu
Thu Sep 13 02:56:51 UTC 2007


As a heads up,

Some testing tonight with one of the existing 9600 baud
satellites showed a 100% success rate from my D700 mobile at a 1
minute rate all the way down to the horizon and I got in one
packet from the D7 HT with a 19" whip.

This is 9600 baud, and so the only mobiles I know that can do
this are all the D7, D700 and D710's.  Receiving the satellite
is going to be minimal on the mobile, but transmitting up with
50W mobile WORKS very WELL.

Once we get full time permission, this will mostly be a mobile
tracking and Email system via satgates into the APRS-IS due to
the difficulty of reception on an omni mobile antnena.  SO it
will be important to have plenty of ground stations listening
and Igating.

Uplink is on 2 meters and downlink is on 435 MHz both at 9600
baud.

SATGATES:

Those of you with spare D7's just sitting around at home most of
the time while you are at work, these make an excellent SATGATE
if you hook them to a modest 19" external ground plane antenna.
The 19" whip is 3/4 wave at UHF and has almost 7 dB of gain
above 30 degrees.  Put the HT CLOSE to the antenna (short coax)
and run the rest of the way to your APRS Igate via a long RS-232
cable.

Since the 19" antenna (and path to the satellite) is useless on
UHF below 30 deg, this antenna does NOT need to be high to see
the horizon.  Just set it low and out of harms way with SHORT
COAX for best signal.

I hope we can make an announcement soon.  This will be neat if
we finally have access to a more permanent and reliable APRS
asset in space (maybe)...

Bob, WB4APR





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