Re: Constellation Modulator delay calculation

Hi Ali - your flowchart has no device and no throttle. You need to add a
throttle.

And I don't the expertise or the time to look at the source code.

So I'm punting back to the list.

-- Cinaed


On 1/10/23 03:10, Ali G. Dezfuli wrote:
> Hi everybody,expertise
>
> 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!