get the data of dsp.spectrum Analyzer

Question

MAWE 2022-8-30

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https://ww2.mathworks.cn/matlabcentral/answers/1790655-get-the-data-of-dsp-spectrum-analyzer

评论： MAWE 2022-8-31

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));

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Answer 1

Abderrahim. B 2022-8-30

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1790655-get-the-data-of-dsp-spectrum-analyzer#answer_1037600

在 MATLAB Online 中打开

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

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MAWE 2022-8-31

在 MATLAB Online 中打开

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})