Why my spectrogram have negative values?
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Jessie Bessel
on 10 Mar 2018
Answered: Kaiwen Zhao
on 14 Mar 2020
In this figure we have a exponential sine wave and his spectrogram. My question is why the spectrogram have negative values? (from -50 to -150)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/171128/image.png)
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Star Strider
on 10 Mar 2018
Assuming he spectrogram function plots the power spectral density (PSD) in decibels. The values are relative, not negative, amplitudes, so -150 dB corresponds to an amplitude of about 3.2E-8.
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