Hi @Ethan Abele,
Typically, in signal processing, the reference power is often assumed to be 1 milliwatt (mW) when dealing with power spectral density (PSD) calculations. This means that the dB values are calculated relative to this reference power. To illustrate this, you can use the following MATLAB code snippet:
% Example signal
fs = 1000; % Sampling frequency
t = 0:1/fs:1-1/fs; % Time vector
x = cos(2*pi*100*t) + randn(size(t)); % Signal with noise
% Compute and plot the spectrogram
spectrogram(x, 256, 250, 256, fs, 'yaxis', 'spectrumtype', 'power');
title('Spectrogram with Power Spectrum in dB');
When utilizing the spectrumtype argument set to "power," the output is indeed represented in decibel. But you are right about one thing, the absence of a specified reference power in the documentation can lead to ambiguity regarding the interpretation of these dB values. Also, without explicit documentation of the reference power level, I would assume a standard reference as mentioned above. So again, based on your comments, the lack of clarity regarding the reference power when using the "power" option is a noteworthy gap in the documentation.
