In the documentation - [`sepctrogram()`](https://www.mathworks.com/help/signal/ref/spectrogram.html).

**Question 1**)`s = spectrogram(signal)` and `spectrogram(signal)` are two commands to plot the spectrogram. However, the variable `s` is complex valued. I am unable to understand which output of the `spectrogram` is used to generate the image plot?

**Question 2**) How to determine the best values of the parameters `window` and `noverlap` ? Should `noverlap` be 50% of the signal length (number of elements in the time series) or 90% etc? What if it is zero then what does it mean? My dataset has sampling time = 1sec. I remember reading somewhere that the window should be at least roughly twice as long as the period of the lowest frequency. So, for my case is `w=2` since frequency = 1?

I was thinking of using `pspectrum(signal,'spectrogram')` which outputs the spectrogram and use the output values as inputs to the `spectrogram()` function. But again, I don't know which output values from `pspectrum` can be used, if at all that is possible.