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[aprssig] ISS Tracking & Pass Information SPEEDS

Bob Bruninga bruninga at usna.edu
Sat Oct 15 13:05:10 UTC 2011


> Wait, how is the radio going to know the 
> direction the satellite is moving from a 
> single courtesy posit?

Yes, you put in 999 in the speed field.  Way back in 1996 or so we defined special speeds for very fast things.  I think 999 means orbital speed 17,500 MPH, 998 is the speed of sound etc.  But it doesnt matter.  It just gives something that the display software can use to draw the speed and direction vector.

Bob, Wb4APR



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