Re: Resampling radio data

[Marcus Müller]

Rough performance estimate:

for a 1/10 transition width filter (which is sufficient to keep 20 of 25 MHz 
Nyquist), you
need an expertly guesstimated [1] 24-ish taps, so go for 25 taps: that happens 
to be
exactly the minimum filter length that we can use in an 25-interpolating 
rational
resampler and still do the full polyphase decomposition trick to run the filter 
at the
least rate of the system.

For "1 tap per branch", I have a rough 60 MS/s for *my PC* in mind. So, My 
guess is that
it will work for 46->50 MS/s, not for 92->100 MS/s, on *my PC*.

Problem: this is an inherently badly multi-threadable workload, unless I'm 
overlooking
something. So, having 48 cores isn't better than having 2.

Best regards,
Marcus

[1]
https://dsp.stackexchange.com/questions/31066/how-many-taps-does-an-fir-filter-need/31077#31077
On 16.02.21 23:09, Jeff Long wrote:
> It's not likely you will get the GR resamplers to run at those rates, but 
> give it a try,
> see if you drop samples, and run "top" to check CPU load.
> 
> On Tue, Feb 16, 2021 at 4:14 PM Mark Koenig 
> <mark.koenig@iubelttechnologies.com
> <mailto:mark.koenig@iubelttechnologies.com>> wrote:
> 
>     Hello,____
> 
>       ____
> 
>     I am receiving data from a radio at 23Msps, and I would like to resample 
> to a rate of
>     25Msps in which my software program can ingest it.  I am aware of the 
> Fractional
>     Resampler and the Rational Resampler.  Is one better than other, take 
> less CPU cycles,
>     etc.?  Is there a different block which would suit my needs more 
> efficiently?  Should
>     I instead look to implement the resampling within C++ as opposed to 
> adding another
>     block to my flowgraph?____
> 
>     __ __
> 
>     I am going to do the above with the following rates:  46Msps -> 50Msps, 
> 92Msps ->
>     100Msps.____
> 
>     __ __
> 
>     Thank you____
> 
>     __ __
> 
>     Mark____
>

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