[amsat-bb] Re: video: program to burn TLEs onto doppler-tuning microcontroller

Gary "Joe" Mayfield gary_mayfield at hotmail.com
Sun Jul 25 20:45:41 PDT 2010

Cool!  Trakbox lives again!!!

Joe kk0sd

-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Bruce Robertson
Sent: Sunday, July 25, 2010 8:51 PM
Subject: [amsat-bb] video: program to burn TLEs onto doppler-tuning

Some of you know about my qrptracker project, which is aiming at a
compact, microcontroller-based doppler tuning device for use in the
field. My previous videos showed an FT-817 controlled by this device
and using a small speaker and CW to announce the bird. I've just
posted a video to YouTube at http://www.youtube.com/user/VE9QRP that
demonstrates the program that is used to load TLEs into the
microcontroller, sync the tracker, etc. It also shows the
microcontroller tuning a TH-D7A handheld, and it shows a LCD display.
My goal now is to make an altoids-tin-sized package that connects to a
TH-D7A or an FT-817, has an LCD display and provides doppler tuning.

In further developments in this project,  I've worked on porting the
SGP4 algorithm to the ATMega644p. (Currently the project uses the
Plan13 algorithm.)It's not an exact port, since the 'double' data type
is not the same length, but with some careful hand-crafting, we're
getting accuracies down to 1/10th of a degree lat and long.
sub-satellite point.

73, Bruce

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