Here it is; many thanks to N8UR for the feedback and corrections ... https://github.com/ckuethe/gnuradio-examples/tree/master/pfb_channelizer
The synthesizer doesn't really look like much when it's running, but you can see on the waterfall where the "extra" channel is used - it's having an existential crisis, full of nothingness and being torn in half... :D https://raw.githubusercontent.com/ckuethe/gnuradio-examples/master/pfb_channelizer/synthesizer_gui.png The channelizer now works as expected; if you generate a set of "this is channel %d" audio files and synthesize them into a band, the flowgraph will extract them again in the proper order. https://raw.githubusercontent.com/ckuethe/gnuradio-examples/master/pfb_channelizer/channelizer_gui.png On Tue, Aug 11, 2015 at 8:16 PM, Chris Kuethe <chris.kue...@gmail.com> wrote: > I have produced a complementary demonstration of the polyphase channel > synthesizer and a tool for generating test signal. As before, it was > developed using the a very recent gnuradio release (3.7.8rc1) so older > installations may be unable to load the grc file. Will publish > shortly... > > As a meta point, I encourage everyone developing with gnuradio to > build test tools and synthetic data sources before starting on the DSP > work (or make some good recordings if you're working with real world > signals). As I am not blessed with 5 or 6 audible NOAA stations, I > wrote a tool to generate distinctive audio streams that could then be > fed through the synthesizer - in this case "flite" was used to convert > the weather reports for 7 different airports to wav files, and a > prologue containing expected channel number and frequency offset was > prepended. This allowed me to very easily hear when/if the channelizer > was correctly selecting the channels I wanted. > > On Thu, Aug 6, 2015 at 7:08 AM, Daniele Nicolodi <dani...@grinta.net> wrote: >> On 22/07/15 15:40, Tom Rondeau wrote: >>> On Wed, Jul 22, 2015 at 4:57 AM, Daniele Nicolodi <dani...@grinta.net >>> <mailto:dani...@grinta.net>> wrote: >>> >>> On 21/07/15 21:39, Tom Rondeau wrote: >>> > Here's my presentation from last GRCon: >>> > >>> > http://gnuradio.squarespace.com/grcon14-presentations#tut-rondeau >>> >>> Hello Tom, >>> >>> browsing through your presentation I see that on page 58 and 59 you >>> recommend to use firdes filter design tool and not optfir to build re >>> reconstruction filter. However, I don't quite understand why the filter >>> generated by one tool is better than the other is this case. >>> >>> Can you please comment on it? >>> >>> Thanks! Cheers, >>> Daniele >>> >>> >>> The shape of this filter matters greatly. The inband, transition, and >>> stop band behavior all determine if the filter can be used for the >>> reconstruction purposes. The image on slide 59 shows the specific >>> transition between the pass band and stop bands. To match that with the >>> PM (i.e., Remez) algorithm, you can't get the same stop band performance >>> for that given transition. Plus the equal response in the stop band is >>> bad when channelizing because all channels will alias at equal powers, >>> whereas the roll off in frequency with the windowed (firdes) filter >>> continues to decrease with f. Remez also produces a pass band ripple, >>> which will also affect things. The ripple with the firdes is not >>> equiripple like Remez promises, but it's much, much smaller. >> >> >> Thanks Tom, very clear explanation. >> >> Cheers, >> Daniele >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > -- > GDB has a 'break' feature; why doesn't it have 'fix' too? -- GDB has a 'break' feature; why doesn't it have 'fix' too? _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
