MATLAB: Is there a way to set the color map and color limits of the dsp.SpectrumAnalyzer without using the spectrum properties GUI

DSP System Toolboxdsp.spectrumanalyzer

I have a piece of script that calls the dsp.SpectrumAnalyzer and uses it as a spectrogram. I would like to be able to hard code the color map and color limits into the script so that I don't have to go through the GUI in the spectrogram window to change these parameters each time it starts. Is there a property that can be set ahead of time that does this?

Best Answer

This cannot be done as there are no command line API's available to set the color properties for Spectrum Analyzer in DSP System Toolbox.

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MATLAB: How to use spectrum analyzer object to show a signal waveform

You can set FrequencyResolutionMethod to 'Window length' to manually adjust the length of signal used to compute the spectrum, e.g.,

Fs = 2500; 
Sineobject1 = dsp.SineWave('SamplesPerFrame',1024,'SampleRate',Fs,'Frequency',100); 
Sineobject2 = dsp.SineWave('SamplesPerFrame',1024,'SampleRate',Fs,'Frequency',1000); 
SA = dsp.SpectrumAnalyzer('SampleRate',Fs,'NumInputPorts',2,'PlotAsTwoSidedSpectrum',... 
    false,'ChannelNames',{'SinewaveInput','NotchOutput'},'ShowLegend',true,...
    'FrequencyResolutionMethod','WindowLength');
step(SA,step(Sineobject1),step(Sineobject2))

MATLAB: Amplitude spectrum

There are a couple things you can do. Let x be your speech signal and fs your sampling frequency. The following two are power estimates.

    plot(psd(spectrum.periodogram,x,'Fs',fs));
If you do not want it in dB:
    psdest = psd(spectrum.periodogram,x,'Fs',fs);
    plot(psdest.Frequencies,psdest.Data);
    xlabel('Hz'); grid on;

Finally, just using fft()

      xdft = fft(x);
      % assume x is even length
      xdft = xdft(1:length(x)/2+1);
      freq = 0:fs/length(x):fs/2;
      plot(freq,abs(xdft));
      xlabel('Hz');

Best Answer

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MATLAB: How to use spectrum analyzer object to show a signal waveform

MATLAB: Amplitude spectrum

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