Article 45292 of sci.geo.satellite-nav: Path: matra.meer.net!news1.best.com!su-news-hub1.bbnplanet.com!cpk-news-hub1.bbnplanet.com!news.bbnplanet.com!dispatch.news.demon.net!demon!g4ikj.demon.co.uk!ArjfHfre From: ROT13 Newsgroups: sci.geo.satellite-nav Subject: Re: Anyone know how high GPS satellites are? Date: Sat, 30 Aug 1997 08:31:27 +0100 Organization: NewsUser *at* g4ikj *dot* demon *dot* co *dot* uk Distribution: world Message-ID: References: <5u87mh$p5c@agate.berkeley.edu> NNTP-Posting-Host: g4ikj.demon.co.uk X-NNTP-Posting-Host: g4ikj.demon.co.uk [158.152.228.117] MIME-Version: 1.0 X-Newsreader: Turnpike Version 3.04 Lines: 103 Xref: matra.meer.net sci.geo.satellite-nav:45292 Ben, Here is an answer I recently sent to someone else - it's probably longer than you wanted :) In article <5u87mh$p5c@agate.berkeley.edu>, Ben Cottrell writes > >My father, who does not have Internet access, asked for me to post this >here. He's curious what the approximate radius (semimajor axis? I don't Here is a sample from the current "almanac" which each SV (Sat. Vehicle) holds about ALL (24 currently) SV's: **** Week 921 almanac for PRN-01 ************ ID: 01 Health: 000 Eccentricity: 3.741264343E-03 Time of Applicability(s): 61440.00000000000 Orbital Inclination(rad): 9.554387331E-01 Rate of Right Ascen(r/s): -7.714607619E-09 SQRT(A) (m^1/2): 5153.73046875000 Right Ascen at TOA(rad): 3.018145084E+00 Argument of Perigee(rad): -1.598538637E+00 Mean Anom(rad): 4.457494989E-02 Af0(s): 2.765655518E-05 Af1(s/s): 0.000000000E+00 week: 921 Things to notice are that this is linked to a specific time - because they are NOT in a geosyncronous nor circular orbits - and the location info will make sense to anyone who's ever tried astronomy, and so used an ephemeris. >know if they're in circular orbit or not) of the orbits of the GPS >satellites is, and if any of them are in stationary (geosynchronous) >orbit. Does anyone have that information handy, or a place where I could >look it up? :-) Thanks! Note that NORAD publish a set of "Two Line Elemements" (TLE's) for every orbiting object, which is a lOT, so they also provide different groupings - e.g. those likely to be visible to the naked eye. Extract from current TLE from sci.space.news (search for subject line): -------Subject: NORAD Two-Line Orbital Element Sets (TLE051)----------- The most current orbital elements from the NORAD two-line element sets are carried on the Celestial WWW: http://www.grove.net/~tkelso/ and are updated daily (when possible). Documentation and tracking software are also available on this system. Element sets (also updated daily) and some documentation and software are available via anonymous ftp from archive.afit.af.mil (129.92.1.66) in the directory pub/space. As a service to the satellite user community, the most current of these elements are uploaded weekly to sci.space.news and rec.radio.amateur.space. This week's elements are provided below. ************************************************************************ - Current Two-Line Element Sets #051 - GPS BII-01 1 19802U 89013A 97235.90785788 -.00000041 00000-0 00000+0 0 4629 2 19802 55.5490 93.4009 0019622 144.3919 215.8044 2.00549718 62396 <...and so on> ************************************************************************ You'll need to visit the above WWW URL to see how to use this info - but there are some FreeWare programs that will show an accurate world/local map with the SV's displayed including their paths - I use a program called "STSORBIT PLUS" available from JPL/NASA, described as: "STSORBIT PLUS Version 9637: Track and display any satellite for which orbital data is available. Used by NASA and the aerospace industry as well as hams and "just plain folks" around the world. Math coprocessor chip recommended. Now includes Multi-Satellite Tracking Feature. By: Dave Ransom, 7130 Avenia Altisima, Rancho Palos Verdes, CA 90275 USA." So, try the listed URL, or try taking sc.space.news for a while :) Now, GPS and the associated details might be more involved than you first thought - there are two on-line documents that provide the full "GPS Standard Positioning Service Signal Specification" and Annex-A - these show you how to read the almanac data, how to clcualte the position of GPS SV's and so on, well worth a look for the curious, try: http://www.navcen.uscg.mil/gps/reports/sigspec/sigspec.htm This newsgroup is generally friendly and helpful - if this hasn't answered you questions, or you've now thought of some different questions, another post here will probably work - but try and phrase the question accurately (some questions are so vaguely phrased that they invite a superficial answer, e.g. YES or NO!). regards, Paul. -- ROT13 OR NewsUser *at* g4ikj *dot* demon *dot* co *dot* uk