On Sat, 2008-06-21 at 11:07 -0700, Eric Blossom wrote: > On Sat, Jun 21, 2008 at 11:01:22AM -0400, Charles Swiger wrote: > > the bit_timing_loop for 16MHz? I'll check in what I have > > Please do this on a branch. >
Ok. > > static const double BANDWIDTH = 0.25; > > > You're still basically hosed if you leave BANDWIDTH at 0.25. > Our bandwidth of interest is 6MHz (TV channel) and you want to run at > 16MHz, you'd need it to be 0.375. Oh, so *thats* what it means! (Remember the thing about frequency in radians/sample ;) > With regard to NTAPS, you'd want to > look at the error between the ideal and actual transfer function over > the frequency range of interest. IIRC the code in gen_interpolator_taps > computes this as its metric. Keep NTAPS a a multiple of 4 since the > SIMD code is going to round it up to that anyway (padding with zeros). > > > > Didn't you try the J.O. Smith resampler? How did that work out? > Yes - I make a block called gr_samplerate_ff linked against Erik de Castro's libsamplerate and it worked fine with audio - dial tone at bizzare sample rates came out sounding normal to the ear - but it just did not work for the bit_timing_loop. What with 1) an external dependancy, 2) it would use up to 25% cpu just at audio rates on a 1.5Ghz Pentium-M, I just moved on to trying new taps for your existing fractional resampler. --Chuck _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
