Forum: GNU Radio Lowpass filter in receive_path.py

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unknown (Guest)
on 2007-06-21 01:36
(Received via mailing list)
Hello,

In receive_path.py, there is this code:

# Design filter to get actual channel we want
sw_decim = 1
chan_coeffs = gr.firdes.low_pass (1.0,                  # gain
                                  sw_decim * self._samples_per_symbol,
                                  # sampling rate
                                  1.0,    # midpoint of trans. band
                                  0.1,    # width of trans. band
                                  gr.firdes.WIN_HANN)   # filter type

So, the approximate pass-band of this filter is from 0 Hz to 1 Hz. Isn't
this a little small? (Input signal must have extremely small bandwidth
to
pass through.)

In am_rcv.py, and other codes the pass-band is more understandable, like
9e3 Hz = midpoint of transition band.

Jonathan Shan
William S. (Guest)
on 2009-05-13 06:29
no I don't understand this either.
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