Re: [amsat-bb] Squint Angle and Winorbit Question

["Frederick M. Spinner" <fspinner@xxxxxxxxxxx>]

WinOrbit was written during AO-13 days.  The antennas on AO-40 are on the 
opposite side of the satellite in the Z axis.

A good reference on what to do to get WinOrbit to display this properly is 
the do in this case is in the FAQ for InstantTrack on the AMSAT site. ( 
http://www.amsat.org/amsat/intro/itfaq.html )

Text follows:
What about the Attitude of AO-40?

Current attitude parameters for AO-40 are available on the AO-40 telemetry 
beacon and (usually) in the AMSAT News Service weekly satellite report.

There's a problem, though. InstantTrack assumes that the high-gain antennas 
on the spacecraft are pointing in the +Z direction (that is, away from the 
kick motor). However, on AO-40
the antennas are mounted on the kick motor side, and point in the -Z 
direction. This means that if you put the regular Bahn coordinates into 
InstantTrack, it will get the squint angles
wrong.

To compensate for this problem using InstantTrack 1.50, you can convert the 
Bahn coordinates to point in the opposite direction. To convert the Bahn 
longitude, add 180. If that number
is 360 or larger, subtract 360. To convert the Bahn latitude, simply negate 
it.

For example, recently as I write this (December 8, 2000) the attitude was 
reported in the beacon as "267/-3". That's a longitude of 267, and a 
latitude of -3. The converted longitude for
InstantTrack is 267 + 180 - 360 = 87, and the converted latitude is +3. So 
the attitude should be entered on the Manual Edit Satellite Elements screen 
as "3,87". Notice that
InstantTrack wants the latitude first, and a comma between them, whereas the 
beacon lists the longitude first and uses a slash between them.

---

This is the same story for WinOrbit, its fairly easy to correct this with a 
calculator.  Minor inconvience, thats all..

Fred W0FMS



>From: "Gary Gonnella" <gary@ridepix.com>
>Reply-To: <gary@ridepix.com>
>To: <amsat-bb@AMSAT.Org>
>Subject: [amsat-bb] Squint Angle and Winorbit Question
>Date: Thu, 6 Sep 2001 12:40:12 -0700
>
>I am using WinOrbit to track AO40 and have put the Alat and Alon 
>information
>into the .ATT file. I got these numbers from the telemetry from the
>satellite but my squint comes up at very high numbers in the range of 120 
>to
>160. Is this really the squint or am I doing something wrong. I have read
>the help file and it says it only needs the Alon/Alat info to calculate the
>squint.
>any help would be appreciated
>
>Gary Gonnella W6RYO
>gary@ridepix.com
>http://www.ridepix.com/w6ryo
>
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