Resampling

GNU Radio
1

Hello,

I am using blks2impl dqpsk modulator/demodulator.

Since demodulator’s “samples_per_symbol” value must be an integer >=2
and
USRP samples at 64 Msamples/s with a 2^(n) possible decimation, I have
to
sample a 2100 kbps carrier (=1050 ksym/s).

I found two blocks that may apparently be used for resampling:

  • rational_resampler()
  • rational_resampler_base_xxx()

I am not sure of which one I should use. Does somebody know the
difference
between them?

I’ve read that rational_resampler_xxx() is a high-level wrapper for
gr.rational_resampler_base_xxx but I don’t understand what it means.

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2

On Wed, Jun 04, 2008 at 03:21:25AM -0700, irene159 wrote:

Hello,

I am using blks2impl dqpsk modulator/demodulator.

Since demodulator’s “samples_per_symbol” value must be an integer >=2 and
USRP samples at 64 Msamples/s with a 2^(n) possible decimation, I have to
sample a 2100 kbps carrier (=1050 ksym/s).

Uhh, the decimation values aren’t that restricted.
They must be EVEN and in [8, 256].

http://gnuradio.org/doc/doxygen/classusrp__standard__rx.html#ebd585937cec3e60f1167cddd100f308

Eric

3

irene159 wrote:

  • rational_resampler_base_xxx()

I am not sure of which one I should use. Does somebody know the difference
between them?

I’ve read that rational_resampler_xxx() is a high-level wrapper for
gr.rational_resampler_base_xxx but I don’t understand what it means.

As Eric said, you can use any even decimation rate.

If you need to resample, you’re better off using the
blks2.rational_resampler block which is a convenient wrapper for
gr.rational_resampler.

Tom