[ao16aprs] APRS via AO-16

[Bob Bruninga <bruninga@nadn.navy.mil>]

Tonight were my first 2 good mobile APRS satellite test passes.  

AO16 was south to north along the east coast rising to a maximum
elevation of 20 degrees.   LO19 was south to north almosts overhead.
No one else was on either bird the entire pass.

UPLINK:  20 W ERP FM to a vertical over a simulated car roof
         1 packet for digipeat  every 10 seconds   

AO16:  I started late, but once I got locked on, I held lock solid all
the way to the horizon.  Of 38 packets 10 were digipeated.  But here is
the pattern after I got locked on (*'s show Xmitted, X's show digi'ed)

AO16: ..........**********************************************
                 X X                            XXXXXXXX

LO19: ********************************************************
                                            |  XXX  XXX        

      South                 center         QSY      north

I was on 145.90 for AO16 and the first 3/4 of LO19.  Since I was
having zero success with LO19, I QSYed the  uplink to 145.88 and
began having success.

So you see, this seems to support the expected poor performance of a
vertical in the center of a pass.  Not just because it is overhead
(this was a 20 deg pass), but because of the perfect cross polarization 
of the vertical with the Pacsat antennas at this geometry. Also it shows
the poor performance of a vertical down at the horizon, but better up a
few degrees..  ALso on the overhead pass (LO19) where you would expect the
early and late portions to be vertical, I did not see much improvement.

One possibilty for the poor southern performance is the orientation of the
pacsat antenna on the top of the bird and/or QRM from the southern USA
which disappears when the birds get north of here..

de WB4APR, Bob



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