On Mon, Dec 1, 2014 at 5:34 PM, Paul Creaser <drpaulcrea...@gmail.com> wrote:
> I've used both the Fractional Resampler and the Rational Resampler so far > with reasonable results. At this stage in the case of the Rational > Resampler, I simply use the Interpolation setting and decimation setting to > form a ratio (taps:None, Fractional BW:0), which then generates the > required > output sample rate. > > One interesting point. When for example resampling from 30.72MHz to > 30.72002MHz, I had a look at the FFTs using the QT Gui Frequency Sink. One > thing that struck me was, the rational resampler was acting as a low pass > filter. At both ends of the spectrum I could see a roll off. > > I am also looking at trying the Polyphase resampler. Well actually I have > tried it, just I haven't figured out, how to choose the parameters yet! > Yes, all of the resamplers are filters. You need to filter whenever you resample a signal. The rational resampler and PFB resampler both try and find a good default filter such that the signal in the original passband is not distorted but and aliasing or images are properly attenuated. However, Bug #745 on our issue tracker suggests that the default RR taps are not correct. I'm planning on looking into that this week. Tom
_______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
