<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body>Kirby's idea sounds good. After all, there are several different orbital velocities (or at least, effective ground track speeds), depending on orbital altitude. Geosynchronous orbit will have a much slower ground track speed than LEO altitudes. And then there's the birds in elliptical orbits instead of circular....<div><br></div><div>Speaking of which, is the reported speed for satellites supposed to be the true tangential orbit velocity, or the ground track projection speed at the Earth's surface? For airplanes, that's not very different, but as the altitude increases, so does the difference.</div><div><br></div><div>Andrew Pavlin, KA2DDO</div><div>author of YAAC</div><br><br>-------- Original message --------<br>From: Kirby <joekirby@gmail.com> <br>Date: 10/11/17 14:34 (GMT-05:00) <br>To: Greg D <ko6th.greg@gmail.com>, Robert Bruninga <bruninga@usna.edu> <br>Cc: TAPR APRS Mailing List <aprssig@tapr.org> <br>Subject: Re: [aprssig] APRS Speed Spec? (plan B) <br><br>How precise do you want to be. 9XX is XX mach.<br><br>space station = 924<br>military = 903<br>concord = 902<br><br>speeds below 900 are actual. works up to about 73774ish mph.<br><br>-- <br><br><br><br><br>_______________________________________________<br>aprssig mailing list<br>aprssig@tapr.org<br>http://www.tapr.org/mailman/listinfo/aprssig<br></body></html>