Use the spectrogram function to plot the spectrogram of multiple single frequency inputs. Define the input signal with different single frequency inputs (0.05 Hz, 0.1 Hz, 0.15 Hz) and use the below code to plot the spectrogram.
N = 1024;
n = 0:N-1;
x = sin(0.05*n)+sin(0.1*n)+sin(0.15*n);
s = spectrogram(x);
The above code gives the Samples vs Frequency spectrogram plot. The output data can be configured as Samples/ time based as needed.
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