get the data of dsp.spectrum Analyzer

Currently, I am using the below code to display the spectrum of the received signal (before receive filtering) using dsp.spectrumAnalyzer. However, I need the data that is shown itself. How can I get it? Also, how can I generate the spectrum as dsp.spectrumAnalyzer manully from sctractch using fft?

data = 2.*randi([0 1], 1e6, 1)-1;


txFilter = comm.RaisedCosineTransmitFilter;

filteredData = txFilter(data);

rxSignal = awgn(filteredData, 20);


freqAnalyzer = dsp.SpectrumAnalyzer('SampleRate',8e6);

freqAnalyzer((rxSignal));

Answer 1

[Abderrahim. B]

Hi!

To get data shown in spectrum analyzer, use getSpectrumData method.

data = 2.*randi([0 1], 1e6, 1)-1;
txFilter = comm.RaisedCosineTransmitFilter;
filteredData = txFilter(data);
rxSignal = awgn(filteredData, 20);
freqAnalyzer = dsp.SpectrumAnalyzer('SampleRate',8e6) ;
freqAnalyzer((rxSignal))
specData = getSpectrumData(freqAnalyzer) ;

figure
plot(specData.FrequencyVector{1,1}, specData.Spectrum{1,1})

Hope this helps

[MAWE]

It seems the specData.Spectrum{1,1} is the absolute value since it's real. If the signal is complex by adding some noise like below, how can I get the complex frequency representation? In other words, how can I get the same spectrum from the fft of rxSignal?

data = 2.*randi([0 1], 1e6, 1)-1;
txFilter = comm.RaisedCosineTransmitFilter;
filteredData = txFilter(data);
L=length(filteredData);
n=(1/(sqrt(2*10^2))).*(randn(L,1)+1i.*randn(L,1))
rxSignal = filterData + n;
freqAnalyzer = dsp.SpectrumAnalyzer('SampleRate',8e6) ;
freqAnalyzer((rxSignal))
specData = getSpectrumData(freqAnalyzer) ;
figure
plot(specData.FrequencyVector{1,1}, specData.Spectrum{1,1})