Forum: GNU Radio inputs with different samplerates

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Martin D. (Guest)
on 2006-04-29 05:32
(Received via mailing list)
Hi all,

Is there any way for a block to process two signals at different
samplerates?

In my work for videodemodulation and synchronisation with gnuradio I
need to process two versions of the data in the same block.

I need the original samplestream at 8 MSPS.
I also need a decimated/lowpassed version of the same signal at a much
lower samplerate.

I can't connect the original and the decimated version to the same block
can I.

The only thing I can do is leave out the decimation, but this would
increase the computational needs enormously.

Is there any trick for doing this.

My only other solution is to reimplement the decimating fir-filter block
inside my new block.

greetings,
Martin
Eric B. (Guest)
on 2006-04-29 05:41
(Received via mailing list)
On Sat, Apr 29, 2006 at 03:28:58AM +0200, Martin D. wrote:
> Hi all,
>
> Is there any way for a block to process two signals at different samplerates?

There's no problem consuming inputs at different rates.  The forecast
routine just needs to "do the right thing".  However, all outputs must
be produced at the same rate.

There's no quick way to work around this.  The immediate problem is
that work and general_work return a single value giving the amount of
output produced on all output streams.  There's a reason that more
advanced languages support mutliple return values...

> In my work for videodemodulation and synchronisation with gnuradio I
> need to process two versions of the data in the same block.

> I need the original samplestream at 8 MSPS.
> I also need a decimated/lowpassed version of the same signal at a much lower samplerate.

> I can't connect the original and the decimated version to the same block can I.
>
> The only thing I can do is leave out the decimation, but this would increase the 
computational needs enormously.
>
> Is there any trick for doing this.
>
> My only other solution is to reimplement the decimating fir-filter block inside my new 
block.
>
> greetings,
> Martin

Not sure if this helped or not ;)

Eric
Martin D. (Guest)
on 2006-04-29 06:14
(Received via mailing list)
Eric B. wrote:
>
>>I need the original samplestream at 8 MSPS.
>>
>>greetings,
>>Martin
>
>
> Not sure if this helped or not ;)
Yes id did.
I only output at a single rate.
Thanks,
Martin
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