Polyphase Filter Bank

Response of single bin from non-windowed FFT.
Note the poor out-of-band rejection compared to polyphase filter bank used in the GALFA spectrometer.

Frequency response of single spectra bin in the GALFA spectrometer.
Note fairly flat response across the bin and excellent out-of-band rejection.

Polyphase filter bank with four times overlap; frequency response of several bins.