         Making your own GPS NAVSTAR TLE file.

The group of utilities in this archive, allow a user to produce
a GPS NAVSTAR TLE (Two Line Element) file from a number of
optional sources. The TLE produced when used on satellite
tracking software can give the position of any of the GPS
satellites to an accuracy better than 6 minutes of arc (1/10th
degree).  This is useful for many amateur hobbies to do with
satellite tracking, tracking with amateur optical telescopes,
satellite rise and set (antenna directionality) and just a
learning exercise to do with almanacs, Keplerian elements and
SGP data algorithms.

The motive for making this software was as a winter hobby, to
learn about GPS and because I have a permanent GPS receiver
(used for R&D) attached to my PC network. I also liked the
concept of clicking a mouse to get my own orbital TLE's directly
off the satellites overhead.  Maybe its useful for you too,
especially if you are at a remote site and do not have access to
the Internet and USSPACECOMS TLE's.

Which utilities you use depend on how you are able to produce
the almanac file. These are the options.

1. Your GPS receiver can output the Almanac in YUMA format.

2. Your GPS receiver can output the Almanac in NMEA format.

3. You have a Motorola Oncore receiver (and perhaps older Motorola
receiver) using the Motorola binary format.

4. You have a Magellan receiver with serial connection to your PC.

5. You have access to the Internet.


Choose the following , based on the above number
------------------------------------------------

1. If your GPS receiver can output the YUMA almanac format
directly, you only need to use "alm2tle.exe". Read alm2tle.txt.
Rename your YUMA file to say "YUMA0.TXT" and then call
"alm2tle 0" and the rest is automatic. Use output file GPS.TLE

2. If your GPS receiver can output an almanac in NMEA mode, read
the file NMEA2ALM.TXT and follow instructions.

3. If you have a Motorola GPS with RS232 connection, read the
file MOT2ALM.TXT and follow instructions.

4. If you have a Magellan GPS with RS232 connection, read the
file MAG2NMEA.TXT and follow instructions.

5. If you have access to the Internet, read the file alm2tle.txt
and follow instructions.

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The 3 exe programs enclosed are all compiled as 16 bit DOS
applications - should also run fine under the various Windows
platforms.

Have fun, Regards Geoff...
