On Mon, 2008-10-27 at 15:03 +0100, Georg Acher wrote:> On Mon, Oct 27, 2008 at 10:37:52AM +0000, Morgan Tørvolt wrote:> > > As I used to work with satellite signals on an earth station, and was> > responsible for the development of measurement techniques, I thought I> > should join in here for some hopefully revelaing info.> > > > I am guessing here of course, but I believe that there is no real SNR> > measurement in any of the tuners available for computers. > > My guess is that it is possible. Actually, it is quite easy for QPSK ;-) You> only need to calculate the distance of the IQ-value from the ideal symbol> center ( (sqrt(0.5),sqrt(0.5)) or whatever) after the> rotator/retiming-block.> Isn't that just Error Vector Magnitude (EVM)? <musing>I suppose over a number of samples, EVM gives you an idea of the noisepower + source transmitter deformation, if the received signal remainsat a constant power. I suppose you could estimate signal strength byexamining amplifier gain settings.</musing> Regards,Andy _______________________________________________linux-dvb mailing listlinux-dvb@xxxxxxxxxxxxxxx://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
