On Tue, 2015-07-21 at 12:01 -0400, discuss-gnuradio-requ...@gnu.org wrote: > Message: 11 > Date: Tue, 21 Jul 2015 11:47:40 +0200 > From: Marcus M?ller <marcus.muel...@ettus.com> > To: discuss-gnuradio@gnu.org > Subject: Re: [Discuss-gnuradio] Run graph/ scheduler overhead > Message-ID: <55ae153c.9050...@ettus.com> > Content-Type: text/plain; charset=windows-1252; format=flowed > > Hi Dennis, > > if I read Fig 4 of [1] correctly, then you 32-delay DC blocker has a > passband starting at let's say 0.025 * f_sample. > I've gone ahead and clicked together a FIR filter that theoretically > should perform as well; its CPU consumption is... tolerable :) > Compare [2]; taps are in the PNG comment. Because this is so quick > and > dirt, I didn't bother to verify I really see 10MS/s throughput -- but > considering the most-used CPU core is tasked 40% of its time only, I > think that's a feasible assumption; plus, you can probably go > further, > if the filter performance doesn't match your needs -- I found that > for > filters > 100taps numerical accuracy of single precision floating > point > arithmetics starts taking its toll, so your amplitude response will > not > 100% be what gr_filter_design shows. Verify with a long averaging Qt > frequency sink or so. > > Best regards, > Marcus > > [1] > http://www.ingelec.uns.edu.ar/pds2803/materiales/articulos/04472252.pdf > [2] http://i.imgur.com/Qmx9q96.png
Hmmm. Since this is ADS-B and phase doesn't matter, how about a differentiator followed by a leaky integrator: IIR filter: Feedforward taps: [1.0 -1.0] Feedback taps: [1.0 -0.99] 4-taps. I have no idea how computationally efficient GnuRadio is at IIR filters. Need a steeper notch at DC, change the -0.99 to -0.9999 or whatever. Regards, Andy > On 21.07.2015 09:02, Dennis Glatting wrote: > > On Mon, 2015-07-13 at 21:43 -0400, Tom Rondeau wrote: > >> On Mon, Jul 13, 2015 at 12:30 AM, West, Nathan > > FYI and following up. > > > > I simplified my graph (below). According to gr-perf-monitorx, and > > gr-ctrlport-monitor agrees, 95% of the the time is spent in > > dc_blocker_cc. > > > > I haven't look at why but clearly that's a problem. _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
