Rectangular mask short-time Fourier transform

In mathematics, a rectangular mask short-time Fourier transform has the simple form of short-time Fourier transform. Other types of the STFT may require more computation time than the rec-STFT.
Define its mask function
We can change "B" for different signal.
Rec-STFT
Inverse form
Property.
Rec-STFT has similar properties with Fourier transform
If formula_10,formula_11and formula_12are their rec-STFTs, then
Rectangular mask "B"'s effect.
From the image, when "B" is smaller, the time resolution is better. Otherwise, when "B" is larger, the frequency resolution is better.
We can choose specified "B" to decide time resolution and frequency resolution.
Advantage and disadvantage.
Advantage
The instantaneous frequency can be observed.
Disadvantage
Higher complexity of computation.
The rec-STFT has an advantage of the least computation time for digital implementation,
but its performance is worse than other types of time-frequency analysis.