DFT Filter Bank Script

Hi guys, i've a problem with a script of maximally decimated DFT FBs. The first implementation as parallel filters works, but when i do the script with polyphase and fft/ifft i obtain an aliasing between channel! For generate prototype i used a simple method written by Mitra for pseudo QMF, and i've modulated with complex exponential in the 1st implementation, and used the fft in 2nd script.

In the 1st figure is shown the input signal hilbert(chirp), while in 2nd the output of the synthesis polyphase bank. I attach also the file for who wants try my filters, and i would be grateful if you help me. :(

The script for parallel bank is DFT_FB.m

The script for polyphase bank is DFT_FB_POLY.m, the others files are subfunction.

Thanks

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[Stefano]

This is filter bank 8 channels:

[emehmetcik]

I get an error saying that the "spectrum_scope" function is missing.

[Stefano]

True,sorry. The function spectrum scope just contains plot(20*log10(abs(fft(signal,length(signal)))))

Answer 1

[Stefano]

This is function spectrum_scope: