[amsat-bb] Re: keps for earthbound objects
alexc at phys.au.dk
Mon Aug 13 14:58:09 PDT 2007
On Mon, 13 Aug 2007 13:30:19 -0700
"Eric Fort" <eric.fort at gmail.com> wrote:
> The antennas in this case are fixed, though a movable solution would be
> nice. the problem is how to get the tracking program to point the
> antennas at a fixed spot and keep them pointed there. I'm considering
> the assembly of a sat-gate that will do double duty on sats and
> terrestrial work so the antennas need to be able to "track" both types
> of targets. notice the quotes around "track"...ultimately I'd like to
> just specify an oblect (norad catalogue number or lat/lon) remotely and
> have the antennas point and remain pointed at the object as my station
> and/or the remote station (object) moves. Im thinking to just have the
> tracking program pull the right set of keps....but I need to create them
> first! I'm also open to ways to do this in ways that may be easier.
> suggestions are welcome.
What you want to do is not possible with a satellite tracking program.
Keplerian elements describe the orbit of a satellite and where the
satellite is at a given time on this orbit. From this information, a
satellite tracking program calculates the position of the satellite at any
Therefore, you would have to define an orbit, where the satellite appears
to be stationary and has practically zero altitude. This is not possible
because a satellite only appears stationary at very high altitudes (e.g.
geostationary orbit at 35600 km above Earth surface) and the orbital
velocity increases as the altitude decreases. In fact, it doesn't even
make much sense to talk about satellite orbits at altitudes less than
100km above the Earth.
I think you will have more luck if you try to find another software for
this task; something that simply points your antenna to a fixed direction.
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