This Python script generates polyphase filter coefficients for yapp_ft, for use while running the latter with PFB turned on. The filter coefficients are made up of a normalized sinc function modulated by a Hanning window. The output is written to a file that yapp_ft expects to find in the current working directory. The format of the filename is coeff_ntaps_nfft_nsubbands.dat. The number of sub-bands, nsubbands is always 1. The filter coefficients are single-precision floating-point.

Usage:

The options are:

• -h or --help: Display this usage information.
• -n or --nfft nfft: Length of the Fourier transform (default is 4096).
• -t or --ntaps ntaps: Number of taps in PFB (default is 8).
• -g or --graphics: Turn on plotting.

Example:

The following generates filter coefficients for a 4-tap filter with 1024 FFT points. It creates a file named coeff_4_1024_1.dat in the current working directory, and also displays a plot of the filter coefficients.