Satellite Tracking - CQ VE9QRP

I am setting out to build an arduino satellite tracker to literally point out location of visible satellite passes, maybe with a laser pointer, maybe just a stick! I have a simple pan-tilt servo setup more or less working but the hard part is locating the satellites. The math is hideously complex but it's a well understood problem and has been nicely solved for me.

This post from last year has code that should do exactly the calculations I need but I'm not getting correct results. The google project repository at has the library and a nice sample with intended results for comparison. It compiles fine but unfortunately the output doesn't match the predicted result.

AZ:333.40 EL: -47.26 RX: 435293340 TX: 145922233 Sat Lat: 28.58 Sat Lon.: 145.88 RR: 4.58
Should be:
AZ:57.07 EL: 4.05 RX 435301728 TX 145919440

I'm hoping the original author spots this or that someone else has tried this and gotten different results so we can compare notes. Alternatively, there's a basic language version of the algorithm written for the BBC microcomputer basic that i could maybe use to bughunt the qrptracker arduino code if anyone has a copy of bbc basic they could let me use.

Well you didn't get it done in time for Field Day this year so you have plenty of time until next year. I wrote a program like this years ago for one of the early HP programmable calculators but I doubt if I can find it now.


The problem was actually a failing atmega328.