Re: [Discuss-gnuradio] "sample delay" in "Decimating FIR Filter" at GRC

[CEL]

Hi Ali,

I went into the GRC file (in gnuradio/gr-filter/grc) and looked that
up: It calls block::declare_sample_delay

https://www.gnuradio.org/doc/doxygen/classgr_1_1block.html#acad5d6e62ea
885cb77d19f72451581c2

(this documentation isn't great and doesn't really say what
declare_sample_delay actually does – we should probably improve that)

The effect of that is that the block itself sees input tags shifted by
the delay, and thus, they are also propagated through the filter with
that delay.

Makes a lot of sense if you, for example, have something like

power_detector_of_kinds_that_tags_start_of_transmission
-> linear_phase_low_pass_filter
-> more_processing

and want the "more_processing", whatever that is, to see the tags the
power detector inserted at "logically" the right position, i.e. shifted
by the constant group delay of your linear phase filter.

Best regards,
Marcus


On Mon, 2018-07-02 at 13:59 +0430, Ali The GREAT! wrote:
> hi all,
> I was wondering what the "Sample Delay" parameter in "Decimating FIR
> Filter" block in GRC does.
> Thanks in advance!
> regards,
> Ali
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

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