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AO-40 Pass #309 Report



As I write the satellite is still being heard [0800 utc, MA: 55, SQ: 76.9].

I was a bit behind AOS as I had lost track of time in the sunny evening.  I
acquired AO-40 at ~ 0430 utc and immediately found the downlink though it
was low in the southern sky [NOVA az=166.5, el=5.3; ACTUAL az=155, el=10].
What was surprising was the very strong signal starting at S-7 and reaching
S-9 within ten minutes at a squint of 35 degrees.  This also produced good
CRC.  Good CRC lasted for about a half hour till squint reached ~48.  I'll
zip and e-mail this to the Amsat-archive in the morning.

I wasn't at the radio continuously so the doppler often caused the
frequency to move off.  What has surprised me is nearly constant reception
all the way to squint 78, and its still very strong [S-5 to S-7].  I've
copied 320/850 blocks of telemetry tonight using ao40rcv.  Since I was not
in the radio room, I don't have the detailed info like last night.  The IF
started at 123.292 and is 123.308.9 right now.  Current range is 48,077 km.

One thing I am noticing is that due to breezy wx, the antenna has been
buffeted some and I can see the signal strength vary with the wind.  The
long 432 and 1296 antenna booms cause a fair wind sail.  This could be a
problem for communicating with the narrow s-band beamwidth.  I wonder if it
is having any effect with capturing good telemetry.

After weeks of getting this station working it is quite gratifying to see
it perform well, now.  I compared my S-9 reception with ao40S_2 spreadsheet
and it predicts my S/N to be 24.6 dB [SQ: 35, Rng=14,260].  S-9 minus S-4.5
noise floor gives a very rough estimate of 18-20 dB S/N...not bad.

Well tomorrow is a work day so I QRT for pass 309 at 0833 utc [squint=79,
signal S-5.5 still going strong].  If I had auto-track/tune I could let it
run the entire pass!  Made the first step toward that by downloading
IT-1.50/ITune today.  It'll be a month till I can afford the Unitrack unit.

Hope everyone finds this info useful.

73, Ed

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