Re: How Do They Do This??

Neil Clifford (clifford@eeyore.demon.co.uk)
Sat, 30 Nov 1996 22:18:03 +0000 (GMT)

John Pike scribbles:

|>Does anyone have a clue as to how they do this, and how one might go

Looks very much to me like a hack to xsat...

|>On the face of it it looks like they have some sorta satellite
|>tracking software running under UNIX [I hope, since our WWW server runs
|>under some flavor of Solaris] that is spontaneously generating a new GIF
|>map every so many seconds. In principle this looks not too hard, though
|>in practice I am kinda at a loss to know where to begin, and in practice
|>I am guessing that if someone actually knew what they were doing [unlike
|>your humble correspondent] this would not be overwhelmingly difficult to
|>emulate.

I suspect so. Shouldn't be a major hurdle to redirect output from eg
xsat or sattrack to a file (X window dump) and then use pbmplus and the
like to generate gif's etc. Automate from cron.

Alternatively you could use any software to generate sub-satellite
points, altitude and thus render visibility maps using gnuplot, IDL, GKS
etc etc.

BTW courtesy of Mike McCants There are SunOS4 and Linux (ELF) versions
of Quicksat 2.12B up on the ftp site 

ftp://ftp.physics.ox.ac.uk/pub/sat/programs/unix/

(also see Mike's home page of course! - unfortunately I don't have the
url there).

As regards the orbcomm tracker I'll have a look at some packages.

May the source be with you...

-- 
Neil Clifford                                <n.clifford@physics.ox.ac.uk>
                       http://www.physics.ox.ac.uk/sat/satintro.html