The frequency-domain representation of a signal reveals important signal characteristics that are difficult to analyze in the time domain. Spectral analysis lets you characterize the frequency content of a signal. Perform real-time spectral analysis of a dynamic signal using the dsp.SpectrumAnalyzer System object™ in MATLAB^® and the Spectrum Analyzer block in Simulink^®. The spectrum analyzer uses the Welch's method of averaging modified periodogram or the filter bank method to compute the spectral data. Both these methods are FFT-based spectral estimation methods that make no assumptions about the input data and can be used with any kind of signal. For more information on the algorithm the spectrum analyzer uses, see Spectral Analysis. In addition to viewing the spectrum, you can also view the spectrogram of the signal in the spectrum analyzer. For an example, see View the Spectrogram Using Spectrum Analyzer.

If you want to acquire this data for post processing in MATLAB, call isNewDataReady and getSpectrumData object functions on the spectrum analyzer object. By calling these functions in the streaming loop, you can acquire the entire spectral data. In Simulink, to acquire the spectral data, create a Spectrum Analyzer Configuration object and run the getSpectrumData function on this object. Note that in Simulink, you can acquire only the last frame of the spectral data shown on the spectrum analyzer.

Alternately, you can use the dsp.SpectrumEstimator System object and Spectrum Estimator block to compute the power spectrum and acquire the spectral data for further processing. To view the spectral data computed by the spectrum estimator, use an array plot. For examples, see Estimate the Power Spectrum in MATLAB and Estimate the Power Spectrum in Simulink.