On Fri, May 23, 2008 at 09:00:31AM -0400, Achilleas Anastasopoulos wrote: > OK, I see. > > 1) Usually in fractional interpolators the trade-off is: more taps vs finer > sampling. It might be possible to increase the number of taps and still be > able to work with only a 12.8 (or 16) real-Msps. > Having said that, I have to admit I haven't looked at exactly what this > particular timing loop is doing.
The current resampler requires only 8 taps at each possible fractional point (1/128). It manages this by having a frequency response that is unconstrained between Fs/4 and Fs/2. That's the source of the constraint on sample rate and occupied bandwidth. The filter design code is in gnuradio-core/src/gen_interpolator_taps. See the README there for additional info and references. We could use a different fractional interpolator, perhaps the one by Julius O. Smith: http://ccrma-www.stanford.edu/~jos/resample. With it, 12.8 real-MS/s or 16 real-MS/s should be possible. Eric _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
