Hi everybody,
I just want to know how the delay of the "Constellation Modulator" block in GRC is calculated.
In fact, whether you set the block's last parameter "truncate filter transient" or not, a delay of 86 samples could be generated, no matter how many points are in the constellation.
This magic number (i.e. 86) also appears in "linear_equalizer_compare.grc" example (in gr-digital/examples/equalizers in modulated_sync_word variable).
I know this delay depends on the "samples per symbol" (sps) parameter and comes from the built-in pulse shaping with its default taps equal:
firdes.root_raised_cosine(32, 32, 1.0, exess_bw, 32*11*sps)
and with the following sps to delay relation:
(sps=2, delay=21)
(sps=4, delay=86)
(sps=8, delay=348)
etc.
my GR version is: v3.11.0.0git-316-gc11667ef
thank you all!