Hey Andrew, Did you have a look at: http://www.arachnoid.com/satfinder/ -Philip Andrew Hakman wrote: >Has anyone else noticed that the USALS algorithms being used in both >the vdr-rotor plugin and MythTV aren't accurate for moderate distances >away from south (or north)? Has anyone else tried to get the real >algorithm from STAB? I've e-mailed them a few times and they seem >reluctant to release the algorithm - they have a good system, but it's >pretty f'in useless without the correct algorithm. What exactly are >they trying to protect? > >I haven't worked out all the trig in the formula being used in vdr or >myth, but it generates almost identical numbers (the differences are >in the thousandths of degrees which is irrelevant anyways) to a much >simpler algorithm I found being used in the DiseqcU plugin for ProgDVB >which uses very simple trig, the diamater of the earth, and the height >of the satellites to calculate the rotation angle. The further away >from south (or north) you calculate the angle for, the more you have >to re-correct back towards south (or north). I haven't put a lot of >thought into it, but a first guess at the problem I think could have >to do with the angle present at the motor shaft. If anyone else has >also noticed this and put some thought into what might be wrong, I'd >sure like to get this figured out. > >As an example, for the furthest east satellite I can see just above >the horizon, DiseqcU and the algorithm used in vdr-rotor and myth >gives an angle of 75.46 degrees, whereas a real USALS receiver >configured with the same reference location and same satellite >location gives a motor angle of 70.4 (which considering how much >further west I have to go from 75.46 to actually get that satellite is >probably correct). > >Andrew Hakman > >_______________________________________________ > >linux-dvb@xxxxxxxxxxx >http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb > >
