Hi Sylvain and Tom, Thanks a lot. It works.
So the "Taps" should contain all the matched filter coefficients for Filter_Size (32) filters instead of just one filter. Then each filter takes SPS (4) out of them to generate a phase-shifted shaping filter. Hence, we have a filterbank with different phases. The optimal sample timing could be estimated as described in Tutorial 7. Best regards, Su Li 2015-04-27 15:58 GMT+02:00 Tom Rondeau <t...@trondeau.com>: > On Mon, Apr 27, 2015 at 9:34 AM, Sylvain Munaut <246...@gmail.com> wrote: > >> Hi, >> >> I am trying to use Polyphase Clock Synchronization (PCS) block to conduct >>> timing synchronization for QPSK signal with half-sine pulse shaping. In the >>> doxygen document of PCS, it says that the "taps" parameter could be the >>> matched filter. Thus, I put the matched filter of half-sine pulse here, >>> [0,sin(pi/4),1,sin(3*pi/4)]. However, the output is all 0. >>> >>> Is there anyone knows how to generate the "taps" parameter here? Any >>> suggestion would be appreciated. Thanks in advance. >>> >> >> I'm not an expert in all the details, but what I know is that the taps >> there need to be generated at "Filter Size" * "Sample Rate". >> >> So I'd try something like [math.sin(math.pi*i/(32*4)) for i in >> range(32*4)] >> >> Cheers, >> >> Sylvain >> > > > What Sylvain said should work, I believe. But you should study the manual > page on this block: > > > http://gnuradio.org/doc/doxygen/classgr_1_1digital_1_1pfb__clock__sync__ccf.html > > Hopefully understanding the way it works will help you understand why the > taps need to be this way. > > Tom > >
_______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
