FIR filter Interpolation vs Resampler

addis_a · November 7, 2014, 10:11am

Hi

I derive the output of a signal, both to an Interpolating FIR filter and
Rational Resampler (in parallel) and then I connect them to a Time Sink
(with 2 inputs).
I use the same interpolation factor for both blocks (interpolation = 4).
I also use in taps the same rcc filter.
In Time Sink plot I observe a time delay in these 2 signals.
Does anyone know why this happens?

Thank you
Daniel

danielb · November 7, 2014, 12:26pm

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Hi Daniel,

because both introduce delays and the delay of one of these is 2
samples longer.

Greetings,
Marcus

On 07.11.2014 10:07, Daniel B. wrote:

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danielb · November 10, 2014, 9:22am

What is the exact meaning of the parameter mu?
http://gnuradio.org/doc/doxygen-3.6/classgr_1_1filter_1_1mmse__fir__interpolator__ff.html
I do not understand it :S

2014-11-07 12:25 GMT+01:00 Marcus Müller [email protected]:

danielb · November 10, 2014, 12:28pm

Hi Carlos,

this might get a little too theoretical to discuss it on the mailing
list, thus I’d like to point you at the Readme [1] file referenced by
the doxygen page, as I think it explains mu as fractional delay quite
nicely.
The readme also references the book where the idea of the MMSE
interpolator will be explained in more detail.

Best regards,
Marcus

[1]

github.com

gnuradio/gnuradio/blob/v3.6.5/gnuradio-core/src/gen_interpolator_taps/README

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# any later version.
#
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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danielb · November 12, 2014, 8:52am

Ok, thank you

2014-11-10 12:26 GMT+01:00 Marcus Müller [email protected]: