Hi, Johannes Stezenbach wrote: > On Mon, Jul 25, 2005 Guy Roussin wrote: >>For an itinerant platform we are trying to develop a simple system for >>automatic positioning of a satellite dish antenna equipped with motors and >>a linux PC with >>dvb-s card, digital compass, inclinometer and GPS. > This sounds like a fun project, but I think there's a problem: > Digital demodulators will only give you useful signal status > information when they are already locked to a signal. You can > then optimize the dish pointing by using the signal indicators > provided by the demodulator. But the dish angle where the signal is > strong enough is rather narrow, which makes it difficult to use > this for seeking the satellte. I think that using analog equipment > is better for this job. Hm, you can use AGC information, they are available even without any lock. For example, pictures like http://developer.elitedvb.net/files/76/shot1.png were made with a normal stv0299 based frontend, using the AGC information. I know that AGC isn't as good as a decent SNR or something, but with a given setup (and provided that there won't be any overamplifications), so that the only moving part is the dish itself, it should correspond more-or-less to the signal quality. you can still fine-tune with the SNR/BER after you found a valid transponder. Felix
