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Re: Satellite tracking for linux

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> I'm looking for a prediction program for linux. I currently have "Predict" 
> but it apparently is unable to have a database of satellites greater than 22.

Predict has a couple of limitations, one of which is its inability to
'display' more than 22 satellites at once, and this is hardcoded in the
program so even in server mode, any client program is also limited to the
same 22 sat maximum.  

You can use multiple tle data files but only one at a time to extend this

Since the KEP mailing list currently send out tle's in one file of around 47
sats, I have hacked the predict source (and the clients) to extend the 22
limit to 50, but the terminal window now needs to be 80x40 rather than the
normal 80x24, so you have to use X-Windows or enable frame-buffer support in
the linux kernel...

One more problem with predict was the way in which satellites are chosen in
that the user selected a satellite by letter. (only so many letters in the
alphabet...).  I removed the toupper function so that the selection now
spans the upper case letters and the lower case letters.

I have added a couple of cosmetic code changes to the program as well.

I have hacked  the 'earthtrack' client a wee bit so that it doen't display 
all the sats at once from the server. Now there are 47 it would look twice as
cluttered as before.. The user can select a sub-range of sats of interest,
and just display them.  The standard earthtrack program in full globe
display mode always put the satellite of interest bang in the centre of the
globe, what I have done is to average out the home qth and satellite of
interest coordinates and centre the globe on that. This has the effect of
keeping both the satellite of interest and the home qth on the globe at
once, even though the globe movements may look a bit odd..

I added an extra magnification setting to earthtrack, to allow the globe to
be placed on top a background image, and with careful choice of image the
result can look quite good..

The actual image that is wrapped around the globe for xplanet does not need
to be the maximum resolution for all modes, so I added the ability to choose
a different resolution map for each mode.. 

	2400 pixels wide for the close in zoomed mode, 
	800 pixels wide for the standard xPlanet globe and 
	480 pixels wide for the smaller globe.

Which for me speeds the calculation up a wee bit on my 200MHz laptop....

If there is any interest in my changes, I'll put them up on my web server...


p.s: I also have mtrack, sattrack and seesat....

- --
John Heaton
JWCS (JANET Web Cache Services), Manchester Computing
The University, Oxford Road, Manchester, M13-9PL, UK

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