Hi Ashish - the short of it is: (samples/sec)/(symbols/sec) = samples/symbol
If the bandwidth is complex, then samples/sec = sampling rate in MHz, and symbols/sec is the baud rate. There are lot of reasons why you would get into trouble by just by changing samples/symbol. You need to post the grc file, or the flowgraph for the problem. -- Cinaed On 12/27/18 9:00 AM, Ashish S wrote: > Hello everyone, > I have some confusion on samples/symbols concept in GNU Radio and it's > driving me crazy when I start to overthink on this. > > *How I did PSK modulation during my studies was : * > Generate random bits, group them according to modulation type > (here considering QPSK) and then pass it through some channel and then > demodulate it. > this whole thing runs in a loop for different values of SNR and I used > to plot BER vs SNR. Here is the quick snapshot > > image.png > > > *Running through the PSK modulation(example provided on GNU radio > tutorials)* > flowgraph : mpsk_stage1.grc > We have a random source which outputs 10k samples in the range of > [0,255] as a byte stream and constellation modulator outputs complex > baseband signal (based on constellation object mapping provided) > This constellation modulator has *samples/symbols *as an input which > needs to be >=2 . > > why is this >=2 and since random source repeats its 10k samples every > period , can't it just group two bits and map as a symbol. ? > When I tend to increase the SPS from 2 to 64 keeping everything the same > , the constellation starts to mess up and the fft plot goes narrower. > Can anyone of you give an insight into this, please ? > > > *When SPS is 4* > image.png > * > * > *When SPS is 2* > > image.png > > *When SPS is 16* > image.png > > *When SPS is 64* > * > * > image.png > > > Ashsih > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
