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
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
When SPS is 2
When SPS is 16
When SPS is 64
Ashsih