On Fri, Mar 04, 2011 at 08:51:28AM -0500, Nick Othieno wrote: > Thanks guys. The ideas looks theoretically sound, but for some reason the grc > setup I have created does not seem to like the idea of very large > interpolation > and decimation values. It does not print out any errors, it just hangs.
Hi Nick, don't use decimations/interpolations that large, the appropriate filters are impossible to get working. Rather, have a look at gr_pfb_arb_resampler_ccf. You need to rationally resample to an approximate sampling rate and let the block do the rest by clever algorithms. Even if you can reach a sampling rate rationally, I usually try and cascade it to get where I want (and I think that's how it's usually done). From 16e6 to 16.3676e6 is, as Ed already mentioned, 40919/40000. GR standard tools won't give you any good anti-aliasing filters for this, but you could go in several steps, such as 29/20 × 17/20 × 83/100. However, working that out already takes longer than setting up gr_pfb_arb_resampler_ccf, or, even easier pfb_arb_resampler_ccf.py, so I'd recommend just using that. MB > > I have attached a copy of my grc setup. > > > On Thu, Mar 3, 2011 at 3:39 PM, Ed Criscuolo <[email protected]> > wrote: > > > On 3/3/11 3:04 PM, Nick Othieno wrote: > > Hi all, > > I would like to get an output of 16.3676 Ms/s. Is it then possible to > set a decimation values of 6.109631223? I am wondering whether > decimation values have to be whole numbers, or whether decimation > values > with fraction parts are allowed. > > > Decimation numbers must be integers. > > What you need to do is set the USRP to acquire at some value close to > what you need, say 16 Ms/s. > > Then use a rational resampler with the proper numbers for interpolation > and decimation to get the desired rate. For instance, at 16 Ms/sec, > set interpolation to 163676 and decimation to 160000. In this case, both > are exactly divisible by 4, so it could even be 40919 & 40000. > > @(^.^)@ Ed > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio -- Karlsruhe Institute of Technology (KIT) Communications Engineering Lab (CEL) Dipl.-Ing. Martin Braun Research Associate Kaiserstraße 12 Building 05.01 76131 Karlsruhe Phone: +49 721 608-43790 Fax: +49 721 608-46071 www.cel.kit.edu KIT -- University of the State of Baden-Württemberg and National Laboratory of the Helmholtz Association
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