On Mon, Aug 25, 2014 at 07:06:11PM +0200, friedtj wrote: > In order to quantify my abilty to receive weather satellite images using > DVB-T running with GNURadio, > I have setup a very simple experiment as follows: > * tune a frequency synthesizer to 137 MHz, FM modulation, 5 kHz deviation and > 2400 Hz FM frequency > * frequency synthesizer output power setup to -91 or -101 dBm (same setting > for all receivers, 2 sets of measurements) > * connect the output of the synthesizer to the input of the DVB-T (in all > cases, a new BNC connector was solder instead > of the original 75-ohm antenna connector), > * plot the RF signal FFT and the FFT of a WBFM demodulator block as found in > GNURadio (always same settings: 30 dB IF > gain and 30 dB RF gain) > * assess the receiver quality by the signal to noise ratio of the FM output.
I'd suggest using something other than FM if you can find a good reference. Looking at the output of an FM demod is going to mask most of the differences you're looking for, and you're much more likely to get a very sharp cutoff between having good output, and not having an intelligible output at all. David
