>From generic_mod_demod.py, here is how the taps are generated. The taps are
then used by a polyphase filterbank-based arbitrary resampler. I think the
answer to your question is 11.
nfilts = 32
ntaps_per_filt = 11
ntaps = nfilts * ntaps_per_filt * int(self._samples_per_symbol)
# make nfilts filters of ntaps each
self.rrc_taps = filter.firdes.root_raised_cosine(
nfilts, # gain
nfilts, # sampling rate based on 32 filters in
resampler
1.0, # symbol rate
self._excess_bw, # excess bandwidth (roll-off factor)
ntaps)
self.rrc_filter =
filter.pfb_arb_resampler_ccf(self._samples_per_symbol,
self.rrc_taps)
On Fri, Aug 6, 2021 at 2:24 PM George Edwards <[email protected]>
wrote:
> Hello GNURadio Community,
>
> The constellation modulator has an RRC filter and we are allowed to set
> the alpha and the number of samples per symbol parameters.
>
> An RRC filter is normally designed to cover a number of symbols to the
> right and left from the center of its impulse response. Anyone know the
> number of symbols covered in the GNURadio Constellation Modulator?
>
> Thanks very much!
>
> Regards,
> George
>
