Re: [amsat-bb] My new AO-40 2.4 GHz downlink isn't working

[Jon Ogden <na9d-2@xxxxxxxxxxxxx>]

Lee's correct.  And additionally, with the satellite going into less and
less favorable ALON/ALATs, the period during which you'll be able to hear
the bird will be less and less.

Make sure that in your tracking program you have the correct ALON/ALAT
entered so that you will be able to determine the squint angle.  Beyond 30
degrees squint, the bird really gets very hard to hear.  I think at 60
degrees there is a sidelobe.

The beacon on AO-40 is very strong and you should be able to at least hear
it (with fading) up to about 30 degrees or so.

Unfortunately, AO-40 is going to be in hibernation very shortly for about 6
weeks or so.  Hopefully you'll be able to test out your setup before they
turn the transponders off.  The beacon will remain on.  Come mid-summer,
things should get much better and you'll have a ball on the bird.

73,

Jon
NA9D

on 4/17/03 8:27 PM, Lee at lee-fl@cfl.rr.com wrote:

> It sounds like you're receiving should be up to the job.  I think you were a
> victim of high squint angles.  Essentially, when the satellite comes through
> the low part of the orbit (perigee) the antennas are pointing away from the
> Earth.  At about the time you probably expected to start hearing the
> satellite (1610 UTC?) the antennas on AO-40 were pointed 127 degrees away
> from you.  As AO-40 made the swing back around to the West the squint was
> still 90 degrees, so you were looking directly into the side of the
> satellite's antenna.  The by the time the satellite went over your Western
> horizon the squint angle was only down to about 40 degrees.  That makes it
> almost impossible for stations to get signals into the satellite.  The
> telemetry beacon is generally 10 db stronger than QSOs should be so you 'll
> find it is not too hard to find when the conditions are right.

-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)

Citizen of the People's Democratic Republik of Illinois

Life Member: ARRL, NRA
Member:  AMSAT, DXCC

http://www.qsl.net/na9d   <- Updated on 1/22/03!!!

"A life lived in fear is a life half lived."


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