FFT Low Pass Filter

From GNU Radio
Jump to navigation Jump to search

This block is a convenience wrapper for the FFT Filter. It implements a lowpass filter using the fast Fourier transform (FFT).

Parameters

(R): Run-time adjustable

Gain
Multiplication factor at the output of the filter. Default: 1
Sample Rate
Default: "samp_rate"
Cutoff Freq
The cutoff frequency (roughly the 3 dB point) of the filter's impulse response.
Transition Width
The frequency difference between the filter's passband and stopband. The ratio of the transition width divided by the sample rate, combined with the window, sets the number of required taps for the filter.
Window
The filter is a basic windowed-sinc filter. This sets the window used. Possible windows are Hamming, Hann, Blackman, Rectangular, Kaiser. Default: Hamming
Beta
This is the value used for the Kaiser window. If any other window is selected, this value is ignored.

Example

NwrReceiver.jpg

This flowgraph filters and demodulates the audio from the US NOAA Weather Radio service. The FFT Low Pass Filter block filters out each signal individually in preparation for demodulation.

Source Files

C++ files
None
Header files
None
Public header files
None
Block definition
filter_fft_low_pass_filter.block.yml