How should I estimate the Signal to noise ratio of a 20 Gbps NRZ PRBS pattern from power spectral density--where should I take the noise floor if I can assume well the noise is AWGN?
I know roughly what the spectra should look like: https://pdfserv.maximintegrated.com/en/an/AN3455.pdf
and how an oscilloscope would take the SNR in the time domain over a distribution of samples: https://gwdata.cdn-anritsu.com/en-us/test-measurement/reffiles/Products-Solutions/11410-00919A-Eye-Diagram-AN.pdf
but how would I correctly go about using the periodogram/ power spectrum to find the SNR? Should I take the noise floor to be where out at where the spectra is flat?
I have a time domain data set of PRBS7 with noise, the data only has one non repeated segment of the PRBS7, sampled with 1ps resolution ( why the MATLAB snr() function gives it out past 250GHz) the resolution isn't so great I think because the length of this sample is 6500ps. Matlab uses a default kaiser window for filtering, I may be able to do better with different filters, but want to see if this is on the right track.