Bastian Preindl wrote: > That are very good news for me! I'm aware about the relations between > SNR and BER - I just wonder about the several ways to estimate the SNR > in GnuRadio. That's exactly the information I lack of - do you have any > documentation/examples/sources for how to accomplish that?
For BPSK, a simple estimator to calculate the signal plus noise to noise ratio is to track the power each in the I and Q portions of demodulated symbol stream. That is, power(I)/power(Q) is a good (but biased) estimate of (S+N)/N for an interval of signal. In practice, you can maintain a running exponential average of each channel and calculate the ratio when needed. A more accurate estimator is to measure the absolute mean and variance of the demodulated symbols, then take ratio of the square of the absolute mean over the variance. This is a true estimate of SNR, but is still biased. Depending on how you need the data for the rest of your application, you could either code these up in Python using existing GNU Radio primitives into a flow graph, or you could write a custom C++ block (which would be marginally faster). > And what about the usage of sound cards as ADC? Can I also obtain SNR > information when I just have an audio stream as source? That entirely depends on what has already happened to the signal prior to it arriving at the sound card. _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
