Re: [Discuss-gnuradio] isolate channels from wideband
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
Re: [Discuss-gnuradio] isolate channels from wideband
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? ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
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
Re: [Discuss-gnuradio] isolate channels from wideband
Very cool! Thanks for the pointer. On 08/02/2015 02:32 PM, Tim K wrote: Just as a heads up, someone mailed this into the mailing list the other day. I think it accomplishes exactly what you all want -- although it doesn't use PFBs as I recall. https://github.com/madengr/ham2mon - Tim On Sun, Aug 2, 2015 at 2:18 PM, John Ackermann N8UR j...@febo.com mailto:j...@febo.com wrote: Hi Chris -- Using the variables, I now have the program working in general. The channel mapping gave me some nightmares, though. I finally decided that you need two maps -- one for the channelizer block, where you do the 4,5,6,7,0,1,2,3 translation, and another for the GUI that is a simple 0..7. With that, it seems to be working well although my WBX front end seems to have been fried as it is more deaf than it used to be. Time to switch to hardware troubleshooting mode... Thanks, again! John On 08/02/2015 12:10 AM, Chris Kuethe wrote: Thanks for pointing out the paste-o. I'll fix that. I'm using gnuradio 3.7.8rc1, which has helper blocks for computing filter taps. You can replace them with variables: pfb_taps = firdes.low_pass(2.0, oversampled_width, noaa_fm_dev * 2, 2500, firdes.WIN_HAMMING, 6.76) lpf_taps = firdes.low_pass(1.0, hardware_rate, noaa_band_width / 2, noaa_chan_width, firdes.WIN_HAMMING, 6.76) On Sat, Aug 1, 2015 at 5:00 PM, John Ackermann N8UR j...@febo.com mailto:j...@febo.com wrote: Thanks much for this, Chris! I look forward to playing with it, but... When I load the flowgraph on my GRC 3.7.6.1 system, I get a Missing Block error for each of lpf_taps and pbf_taps, triggering errors in the xfft and channelizer blocks. I also had an error in the Multiply Const block coming out of channel 7. but that was caused by a missing space before else in the evaluation. Help? But thanks so much for taking this on. It's the perfect starting point for some projects I've been wanting to work on! John On 08/01/2015 03:26 PM, Chris Kuethe wrote: OK, Here it is... at least, a beta version. I have yet to come up with a concise explanation of the channel map and why you'd want to oversample, but it is functional. This flowgraph would work equally well by directly connecting all the ports together, but I'm a big fan of using virtual sources and sinks to make the design somewhat self-documenting.. On Sat, Aug 1, 2015 at 4:55 AM, Markus Heller hel...@relix.de mailto:hel...@relix.de mailto:hel...@relix.de mailto:hel...@relix.de wrote: Great! Thanks! I'm very curious! br/vy73 markus dl8rds Am Freitag, den 31.07.2015, 14:34 -0700 schrieb Chris Kuethe: OK, I have a mostly working flowgraph and am now adding comment to all the blocks explaining why I'm doing this or that. Will publish tonight or tomorrow. On Tue, Jul 21, 2015 at 11:56 AM, Chris Kuethe chris.kue...@gmail.com mailto:chris.kue...@gmail.com mailto:chris.kue...@gmail.com mailto:chris.kue...@gmail.com wrote: Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com mailto:mle...@ripnet.com mailto:mle...@ripnet.com mailto:mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19 tel:21.07.2015%2019 tel:21.07.2015%2019:51, Richard Bell wrote: GNU Radio has channelizers
Re: [Discuss-gnuradio] isolate channels from wideband
Just as a heads up, someone mailed this into the mailing list the other day. I think it accomplishes exactly what you all want -- although it doesn't use PFBs as I recall. https://github.com/madengr/ham2mon - Tim On Sun, Aug 2, 2015 at 2:18 PM, John Ackermann N8UR j...@febo.com wrote: Hi Chris -- Using the variables, I now have the program working in general. The channel mapping gave me some nightmares, though. I finally decided that you need two maps -- one for the channelizer block, where you do the 4,5,6,7,0,1,2,3 translation, and another for the GUI that is a simple 0..7. With that, it seems to be working well although my WBX front end seems to have been fried as it is more deaf than it used to be. Time to switch to hardware troubleshooting mode... Thanks, again! John On 08/02/2015 12:10 AM, Chris Kuethe wrote: Thanks for pointing out the paste-o. I'll fix that. I'm using gnuradio 3.7.8rc1, which has helper blocks for computing filter taps. You can replace them with variables: pfb_taps = firdes.low_pass(2.0, oversampled_width, noaa_fm_dev * 2, 2500, firdes.WIN_HAMMING, 6.76) lpf_taps = firdes.low_pass(1.0, hardware_rate, noaa_band_width / 2, noaa_chan_width, firdes.WIN_HAMMING, 6.76) On Sat, Aug 1, 2015 at 5:00 PM, John Ackermann N8UR j...@febo.com wrote: Thanks much for this, Chris! I look forward to playing with it, but... When I load the flowgraph on my GRC 3.7.6.1 system, I get a Missing Block error for each of lpf_taps and pbf_taps, triggering errors in the xfft and channelizer blocks. I also had an error in the Multiply Const block coming out of channel 7. but that was caused by a missing space before else in the evaluation. Help? But thanks so much for taking this on. It's the perfect starting point for some projects I've been wanting to work on! John On 08/01/2015 03:26 PM, Chris Kuethe wrote: OK, Here it is... at least, a beta version. I have yet to come up with a concise explanation of the channel map and why you'd want to oversample, but it is functional. This flowgraph would work equally well by directly connecting all the ports together, but I'm a big fan of using virtual sources and sinks to make the design somewhat self-documenting.. On Sat, Aug 1, 2015 at 4:55 AM, Markus Heller hel...@relix.de mailto:hel...@relix.de wrote: Great! Thanks! I'm very curious! br/vy73 markus dl8rds Am Freitag, den 31.07.2015, 14:34 -0700 schrieb Chris Kuethe: OK, I have a mostly working flowgraph and am now adding comment to all the blocks explaining why I'm doing this or that. Will publish tonight or tomorrow. On Tue, Jul 21, 2015 at 11:56 AM, Chris Kuethe chris.kue...@gmail.com mailto:chris.kue...@gmail.com wrote: Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com mailto:mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19 tel:21.07.2015%2019:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough). Now you get a long filter. Copy and paste the filter coefficients from gr_filter_design to your PFB filter taps property. Set your channelizers number of channels according to your plans -- 40, if you want to get all the 40 25kHz channels in 2MHz. You get a block with 40 outputs!
Re: [Discuss-gnuradio] isolate channels from wideband
Yes, I saw that, and have not yet had time to look at it. I went with NOAA weather radio because it's always on and I can see a few of the frequencies which makes it a great test source ... my local hams aren't always as predictable, but channelizing your local repeaters would be a very fine use of a PFB On Sun, Aug 2, 2015 at 11:32 AM, Tim K tpkues...@gmail.com wrote: Just as a heads up, someone mailed this into the mailing list the other day. I think it accomplishes exactly what you all want -- although it doesn't use PFBs as I recall. https://github.com/madengr/ham2mon - Tim On Sun, Aug 2, 2015 at 2:18 PM, John Ackermann N8UR j...@febo.com wrote: Hi Chris -- Using the variables, I now have the program working in general. The channel mapping gave me some nightmares, though. I finally decided that you need two maps -- one for the channelizer block, where you do the 4,5,6,7,0,1,2,3 translation, and another for the GUI that is a simple 0..7. With that, it seems to be working well although my WBX front end seems to have been fried as it is more deaf than it used to be. Time to switch to hardware troubleshooting mode... Thanks, again! John On 08/02/2015 12:10 AM, Chris Kuethe wrote: Thanks for pointing out the paste-o. I'll fix that. I'm using gnuradio 3.7.8rc1, which has helper blocks for computing filter taps. You can replace them with variables: pfb_taps = firdes.low_pass(2.0, oversampled_width, noaa_fm_dev * 2, 2500, firdes.WIN_HAMMING, 6.76) lpf_taps = firdes.low_pass(1.0, hardware_rate, noaa_band_width / 2, noaa_chan_width, firdes.WIN_HAMMING, 6.76) On Sat, Aug 1, 2015 at 5:00 PM, John Ackermann N8UR j...@febo.com wrote: Thanks much for this, Chris! I look forward to playing with it, but... When I load the flowgraph on my GRC 3.7.6.1 system, I get a Missing Block error for each of lpf_taps and pbf_taps, triggering errors in the xfft and channelizer blocks. I also had an error in the Multiply Const block coming out of channel 7. but that was caused by a missing space before else in the evaluation. Help? But thanks so much for taking this on. It's the perfect starting point for some projects I've been wanting to work on! John On 08/01/2015 03:26 PM, Chris Kuethe wrote: OK, Here it is... at least, a beta version. I have yet to come up with a concise explanation of the channel map and why you'd want to oversample, but it is functional. This flowgraph would work equally well by directly connecting all the ports together, but I'm a big fan of using virtual sources and sinks to make the design somewhat self-documenting.. On Sat, Aug 1, 2015 at 4:55 AM, Markus Heller hel...@relix.de mailto:hel...@relix.de wrote: Great! Thanks! I'm very curious! br/vy73 markus dl8rds Am Freitag, den 31.07.2015, 14:34 -0700 schrieb Chris Kuethe: OK, I have a mostly working flowgraph and am now adding comment to all the blocks explaining why I'm doing this or that. Will publish tonight or tomorrow. On Tue, Jul 21, 2015 at 11:56 AM, Chris Kuethe chris.kue...@gmail.com mailto:chris.kue...@gmail.com wrote: Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com mailto:mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19 tel:21.07.2015%2019:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB
Re: [Discuss-gnuradio] isolate channels from wideband
That's because of the first LPF - I made it kind of tight. If you change it from noaa_band_width to oversampled_width, that droop goes away. On Sun, Aug 2, 2015 at 12:06 PM, John Ackermann N8UR j...@febo.com wrote: One more thing -- it appears that the lowest frequency channel, 162.400 MHz, has an odd response, with lower overall amplitude and a significant droop in the middle compared to the other channels. Any idea what's causing that? Attached are my modified version of Chris' .grc file, along with a screenshot of the channelizer output from the GUI. John On 08/02/2015 02:18 PM, John Ackermann N8UR wrote: Hi Chris -- Using the variables, I now have the program working in general. The channel mapping gave me some nightmares, though. I finally decided that you need two maps -- one for the channelizer block, where you do the 4,5,6,7,0,1,2,3 translation, and another for the GUI that is a simple 0..7. With that, it seems to be working well although my WBX front end seems to have been fried as it is more deaf than it used to be. Time to switch to hardware troubleshooting mode... Thanks, again! John On 08/02/2015 12:10 AM, Chris Kuethe wrote: Thanks for pointing out the paste-o. I'll fix that. I'm using gnuradio 3.7.8rc1, which has helper blocks for computing filter taps. You can replace them with variables: pfb_taps = firdes.low_pass(2.0, oversampled_width, noaa_fm_dev * 2, 2500, firdes.WIN_HAMMING, 6.76) lpf_taps = firdes.low_pass(1.0, hardware_rate, noaa_band_width / 2, noaa_chan_width, firdes.WIN_HAMMING, 6.76) On Sat, Aug 1, 2015 at 5:00 PM, John Ackermann N8UR j...@febo.com wrote: Thanks much for this, Chris! I look forward to playing with it, but... When I load the flowgraph on my GRC 3.7.6.1 system, I get a Missing Block error for each of lpf_taps and pbf_taps, triggering errors in the xfft and channelizer blocks. I also had an error in the Multiply Const block coming out of channel 7. but that was caused by a missing space before else in the evaluation. Help? But thanks so much for taking this on. It's the perfect starting point for some projects I've been wanting to work on! John On 08/01/2015 03:26 PM, Chris Kuethe wrote: OK, Here it is... at least, a beta version. I have yet to come up with a concise explanation of the channel map and why you'd want to oversample, but it is functional. This flowgraph would work equally well by directly connecting all the ports together, but I'm a big fan of using virtual sources and sinks to make the design somewhat self-documenting.. On Sat, Aug 1, 2015 at 4:55 AM, Markus Heller hel...@relix.de mailto:hel...@relix.de wrote: Great! Thanks! I'm very curious! br/vy73 markus dl8rds Am Freitag, den 31.07.2015, 14:34 -0700 schrieb Chris Kuethe: OK, I have a mostly working flowgraph and am now adding comment to all the blocks explaining why I'm doing this or that. Will publish tonight or tomorrow. On Tue, Jul 21, 2015 at 11:56 AM, Chris Kuethe chris.kue...@gmail.com mailto:chris.kue...@gmail.com wrote: Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com mailto:mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19 tel:21.07.2015%2019:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough).
Re: [Discuss-gnuradio] isolate channels from wideband
Hi Chris -- Using the variables, I now have the program working in general. The channel mapping gave me some nightmares, though. I finally decided that you need two maps -- one for the channelizer block, where you do the 4,5,6,7,0,1,2,3 translation, and another for the GUI that is a simple 0..7. With that, it seems to be working well although my WBX front end seems to have been fried as it is more deaf than it used to be. Time to switch to hardware troubleshooting mode... Thanks, again! John On 08/02/2015 12:10 AM, Chris Kuethe wrote: Thanks for pointing out the paste-o. I'll fix that. I'm using gnuradio 3.7.8rc1, which has helper blocks for computing filter taps. You can replace them with variables: pfb_taps = firdes.low_pass(2.0, oversampled_width, noaa_fm_dev * 2, 2500, firdes.WIN_HAMMING, 6.76) lpf_taps = firdes.low_pass(1.0, hardware_rate, noaa_band_width / 2, noaa_chan_width, firdes.WIN_HAMMING, 6.76) On Sat, Aug 1, 2015 at 5:00 PM, John Ackermann N8UR j...@febo.com wrote: Thanks much for this, Chris! I look forward to playing with it, but... When I load the flowgraph on my GRC 3.7.6.1 system, I get a Missing Block error for each of lpf_taps and pbf_taps, triggering errors in the xfft and channelizer blocks. I also had an error in the Multiply Const block coming out of channel 7. but that was caused by a missing space before else in the evaluation. Help? But thanks so much for taking this on. It's the perfect starting point for some projects I've been wanting to work on! John On 08/01/2015 03:26 PM, Chris Kuethe wrote: OK, Here it is... at least, a beta version. I have yet to come up with a concise explanation of the channel map and why you'd want to oversample, but it is functional. This flowgraph would work equally well by directly connecting all the ports together, but I'm a big fan of using virtual sources and sinks to make the design somewhat self-documenting.. On Sat, Aug 1, 2015 at 4:55 AM, Markus Heller hel...@relix.de mailto:hel...@relix.de wrote: Great! Thanks! I'm very curious! br/vy73 markus dl8rds Am Freitag, den 31.07.2015, 14:34 -0700 schrieb Chris Kuethe: OK, I have a mostly working flowgraph and am now adding comment to all the blocks explaining why I'm doing this or that. Will publish tonight or tomorrow. On Tue, Jul 21, 2015 at 11:56 AM, Chris Kuethe chris.kue...@gmail.com mailto:chris.kue...@gmail.com wrote: Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com mailto:mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19 tel:21.07.2015%2019:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough). Now you get a long filter. Copy and paste the filter coefficients from gr_filter_design to your PFB filter taps property. Set your channelizers number of channels according to your plans -- 40, if you want to get all the 40 25kHz channels in 2MHz. You get a block with 40 outputs! Explaining things like channel mapping is best done by pointing you at the official documentation: [3] Greetings! Marcus [1] Hamming is not always the best choice, I'd try that, Blackman-harris, and Kaiser. I personally like harris in this case -- we want to get a full channel, two adjacent channels are usually not
Re: [Discuss-gnuradio] isolate channels from wideband
Thanks! On 08/02/2015 03:11 PM, Chris Kuethe wrote: That's because of the first LPF - I made it kind of tight. If you change it from noaa_band_width to oversampled_width, that droop goes away. On Sun, Aug 2, 2015 at 12:06 PM, John Ackermann N8UR j...@febo.com wrote: One more thing -- it appears that the lowest frequency channel, 162.400 MHz, has an odd response, with lower overall amplitude and a significant droop in the middle compared to the other channels. Any idea what's causing that? Attached are my modified version of Chris' .grc file, along with a screenshot of the channelizer output from the GUI. John On 08/02/2015 02:18 PM, John Ackermann N8UR wrote: Hi Chris -- Using the variables, I now have the program working in general. The channel mapping gave me some nightmares, though. I finally decided that you need two maps -- one for the channelizer block, where you do the 4,5,6,7,0,1,2,3 translation, and another for the GUI that is a simple 0..7. With that, it seems to be working well although my WBX front end seems to have been fried as it is more deaf than it used to be. Time to switch to hardware troubleshooting mode... Thanks, again! John On 08/02/2015 12:10 AM, Chris Kuethe wrote: Thanks for pointing out the paste-o. I'll fix that. I'm using gnuradio 3.7.8rc1, which has helper blocks for computing filter taps. You can replace them with variables: pfb_taps = firdes.low_pass(2.0, oversampled_width, noaa_fm_dev * 2, 2500, firdes.WIN_HAMMING, 6.76) lpf_taps = firdes.low_pass(1.0, hardware_rate, noaa_band_width / 2, noaa_chan_width, firdes.WIN_HAMMING, 6.76) On Sat, Aug 1, 2015 at 5:00 PM, John Ackermann N8UR j...@febo.com wrote: Thanks much for this, Chris! I look forward to playing with it, but... When I load the flowgraph on my GRC 3.7.6.1 system, I get a Missing Block error for each of lpf_taps and pbf_taps, triggering errors in the xfft and channelizer blocks. I also had an error in the Multiply Const block coming out of channel 7. but that was caused by a missing space before else in the evaluation. Help? But thanks so much for taking this on. It's the perfect starting point for some projects I've been wanting to work on! John On 08/01/2015 03:26 PM, Chris Kuethe wrote: OK, Here it is... at least, a beta version. I have yet to come up with a concise explanation of the channel map and why you'd want to oversample, but it is functional. This flowgraph would work equally well by directly connecting all the ports together, but I'm a big fan of using virtual sources and sinks to make the design somewhat self-documenting.. On Sat, Aug 1, 2015 at 4:55 AM, Markus Heller hel...@relix.de mailto:hel...@relix.de wrote: Great! Thanks! I'm very curious! br/vy73 markus dl8rds Am Freitag, den 31.07.2015, 14:34 -0700 schrieb Chris Kuethe: OK, I have a mostly working flowgraph and am now adding comment to all the blocks explaining why I'm doing this or that. Will publish tonight or tomorrow. On Tue, Jul 21, 2015 at 11:56 AM, Chris Kuethe chris.kue...@gmail.com mailto:chris.kue...@gmail.com wrote: Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com mailto:mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19 tel:21.07.2015%2019:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough).
Re: [Discuss-gnuradio] isolate channels from wideband
Great! Thanks! I'm very curious! br/vy73 markus dl8rds Am Freitag, den 31.07.2015, 14:34 -0700 schrieb Chris Kuethe: OK, I have a mostly working flowgraph and am now adding comment to all the blocks explaining why I'm doing this or that. Will publish tonight or tomorrow. On Tue, Jul 21, 2015 at 11:56 AM, Chris Kuethe chris.kue...@gmail.com wrote: Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough). Now you get a long filter. Copy and paste the filter coefficients from gr_filter_design to your PFB filter taps property. Set your channelizers number of channels according to your plans -- 40, if you want to get all the 40 25kHz channels in 2MHz. You get a block with 40 outputs! Explaining things like channel mapping is best done by pointing you at the official documentation: [3] Greetings! Marcus [1] Hamming is not always the best choice, I'd try that, Blackman-harris, and Kaiser. I personally like harris in this case -- we want to get a full channel, two adjacent channels are usually not occupied, and as soon as we pass the stopband frequency, we're basically at -100dB. [2] assuming you want to use 2MS/s for your 2MHz wide band, 2MHz sampling rate, and assuming 25kHz wide channels, 12.5kHz cut off frequency, 25kHz start of stoppband. I get something like 440 taps. [3] https://gnuradio.org/doc/doxygen/classgr_1_1filter_1_1pfb__channelizer__ccf.html ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ 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? ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
Thanks for pointing out the paste-o. I'll fix that. I'm using gnuradio 3.7.8rc1, which has helper blocks for computing filter taps. You can replace them with variables: pfb_taps = firdes.low_pass(2.0, oversampled_width, noaa_fm_dev * 2, 2500, firdes.WIN_HAMMING, 6.76) lpf_taps = firdes.low_pass(1.0, hardware_rate, noaa_band_width / 2, noaa_chan_width, firdes.WIN_HAMMING, 6.76) On Sat, Aug 1, 2015 at 5:00 PM, John Ackermann N8UR j...@febo.com wrote: Thanks much for this, Chris! I look forward to playing with it, but... When I load the flowgraph on my GRC 3.7.6.1 system, I get a Missing Block error for each of lpf_taps and pbf_taps, triggering errors in the xfft and channelizer blocks. I also had an error in the Multiply Const block coming out of channel 7. but that was caused by a missing space before else in the evaluation. Help? But thanks so much for taking this on. It's the perfect starting point for some projects I've been wanting to work on! John On 08/01/2015 03:26 PM, Chris Kuethe wrote: OK, Here it is... at least, a beta version. I have yet to come up with a concise explanation of the channel map and why you'd want to oversample, but it is functional. This flowgraph would work equally well by directly connecting all the ports together, but I'm a big fan of using virtual sources and sinks to make the design somewhat self-documenting.. On Sat, Aug 1, 2015 at 4:55 AM, Markus Heller hel...@relix.de mailto:hel...@relix.de wrote: Great! Thanks! I'm very curious! br/vy73 markus dl8rds Am Freitag, den 31.07.2015, 14:34 -0700 schrieb Chris Kuethe: OK, I have a mostly working flowgraph and am now adding comment to all the blocks explaining why I'm doing this or that. Will publish tonight or tomorrow. On Tue, Jul 21, 2015 at 11:56 AM, Chris Kuethe chris.kue...@gmail.com mailto:chris.kue...@gmail.com wrote: Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com mailto:mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19 tel:21.07.2015%2019:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough). Now you get a long filter. Copy and paste the filter coefficients from gr_filter_design to your PFB filter taps property. Set your channelizers number of channels according to your plans -- 40, if you want to get all the 40 25kHz channels in 2MHz. You get a block with 40 outputs! Explaining things like channel mapping is best done by pointing you at the official documentation: [3] Greetings! Marcus [1] Hamming is not always the best choice, I'd try that, Blackman-harris, and Kaiser. I personally like harris in this case -- we want to get a full channel, two adjacent channels are usually not occupied, and as soon as we pass the stopband frequency, we're basically at -100dB. [2] assuming you want to use 2MS/s for your 2MHz wide band, 2MHz sampling rate, and assuming 25kHz wide channels, 12.5kHz cut off frequency, 25kHz start of stoppband. I get something like 440 taps. [3] https://gnuradio.org/doc/doxygen/classgr_1_1filter_1_1pfb__channelizer__ccf.html ___ Discuss-gnuradio mailing list
Re: [Discuss-gnuradio] isolate channels from wideband
Well, Tom, nice work is a definite understatement. ... More than excellent work. Awesome usage of virtual sinks. Comments are much needed and make it easier to understand. Personally haven't seen anything like that before mailed within this group. On Sat, Aug 1, 2015 at 10:37 PM, Tom Rondeau t...@trondeau.com wrote: On Sat, Aug 1, 2015 at 3:36 PM, Tom Rondeau t...@trondeau.com wrote: On Sat, Aug 1, 2015 at 3:26 PM, Chris Kuethe chris.kue...@gmail.com wrote: OK, Here it is... at least, a beta version. I have yet to come up with a concise explanation of the channel map and why you'd want to oversample, but it is functional. Check out my paper from WSR'14: http://www.trondeau.com/examples/2014/1/23/pfb-channelizers-and-synthesizers.html That might help clear some things up about the oversampling and channel mapping. Tom This flowgraph would work equally well by directly connecting all the ports together, but I'm a big fan of using virtual sources and sinks to make the design somewhat self-documenting.. Also: Nice work! Tom ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
Thanks much for this, Chris! I look forward to playing with it, but... When I load the flowgraph on my GRC 3.7.6.1 system, I get a Missing Block error for each of lpf_taps and pbf_taps, triggering errors in the xfft and channelizer blocks. I also had an error in the Multiply Const block coming out of channel 7. but that was caused by a missing space before else in the evaluation. Help? But thanks so much for taking this on. It's the perfect starting point for some projects I've been wanting to work on! John On 08/01/2015 03:26 PM, Chris Kuethe wrote: OK, Here it is... at least, a beta version. I have yet to come up with a concise explanation of the channel map and why you'd want to oversample, but it is functional. This flowgraph would work equally well by directly connecting all the ports together, but I'm a big fan of using virtual sources and sinks to make the design somewhat self-documenting.. On Sat, Aug 1, 2015 at 4:55 AM, Markus Heller hel...@relix.de mailto:hel...@relix.de wrote: Great! Thanks! I'm very curious! br/vy73 markus dl8rds Am Freitag, den 31.07.2015, 14:34 -0700 schrieb Chris Kuethe: OK, I have a mostly working flowgraph and am now adding comment to all the blocks explaining why I'm doing this or that. Will publish tonight or tomorrow. On Tue, Jul 21, 2015 at 11:56 AM, Chris Kuethe chris.kue...@gmail.com mailto:chris.kue...@gmail.com wrote: Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com mailto:mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19 tel:21.07.2015%2019:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough). Now you get a long filter. Copy and paste the filter coefficients from gr_filter_design to your PFB filter taps property. Set your channelizers number of channels according to your plans -- 40, if you want to get all the 40 25kHz channels in 2MHz. You get a block with 40 outputs! Explaining things like channel mapping is best done by pointing you at the official documentation: [3] Greetings! Marcus [1] Hamming is not always the best choice, I'd try that, Blackman-harris, and Kaiser. I personally like harris in this case -- we want to get a full channel, two adjacent channels are usually not occupied, and as soon as we pass the stopband frequency, we're basically at -100dB. [2] assuming you want to use 2MS/s for your 2MHz wide band, 2MHz sampling rate, and assuming 25kHz wide channels, 12.5kHz cut off frequency, 25kHz start of stoppband. I get something like 440 taps. [3] https://gnuradio.org/doc/doxygen/classgr_1_1filter_1_1pfb__channelizer__ccf.html ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org mailto:Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org mailto: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?
Re: [Discuss-gnuradio] isolate channels from wideband
On Sat, Aug 1, 2015 at 3:36 PM, Tom Rondeau t...@trondeau.com wrote: On Sat, Aug 1, 2015 at 3:26 PM, Chris Kuethe chris.kue...@gmail.com wrote: OK, Here it is... at least, a beta version. I have yet to come up with a concise explanation of the channel map and why you'd want to oversample, but it is functional. Check out my paper from WSR'14: http://www.trondeau.com/examples/2014/1/23/pfb-channelizers-and-synthesizers.html That might help clear some things up about the oversampling and channel mapping. Tom This flowgraph would work equally well by directly connecting all the ports together, but I'm a big fan of using virtual sources and sinks to make the design somewhat self-documenting.. Also: Nice work! Tom ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
OK, I have a mostly working flowgraph and am now adding comment to all the blocks explaining why I'm doing this or that. Will publish tonight or tomorrow. On Tue, Jul 21, 2015 at 11:56 AM, Chris Kuethe chris.kue...@gmail.com wrote: Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough). Now you get a long filter. Copy and paste the filter coefficients from gr_filter_design to your PFB filter taps property. Set your channelizers number of channels according to your plans -- 40, if you want to get all the 40 25kHz channels in 2MHz. You get a block with 40 outputs! Explaining things like channel mapping is best done by pointing you at the official documentation: [3] Greetings! Marcus [1] Hamming is not always the best choice, I'd try that, Blackman-harris, and Kaiser. I personally like harris in this case -- we want to get a full channel, two adjacent channels are usually not occupied, and as soon as we pass the stopband frequency, we're basically at -100dB. [2] assuming you want to use 2MS/s for your 2MHz wide band, 2MHz sampling rate, and assuming 25kHz wide channels, 12.5kHz cut off frequency, 25kHz start of stoppband. I get something like 440 taps. [3] https://gnuradio.org/doc/doxygen/classgr_1_1filter_1_1pfb__channelizer__ccf.html ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ 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
Re: [Discuss-gnuradio] isolate channels from wideband
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 ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
On Wed, Jul 22, 2015 at 4:57 AM, Daniele Nicolodi 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. Tom ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
Based on the plot of resulting figures the firdes designed filter has more out of band rejection. It's a trade-off between number of taps and rejection. We're good enough (computationally) at doing fir filters that 20 extra taps 25dB of attenuation is worth it. -Nathan On Wed, Jul 22, 2015 at 4:57 AM, Daniele Nicolodi 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 ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
Or, given a regular channel spacing, you can use a polyphase filterbank to split it into multiple narrow-band channels. Cheers, Martin On 21.07.2015 09:10, Stephen Harrison wrote: A simple way in GNURadio is to use the frequency xlating fir filter to select individual channels. On Tue, Jul 21, 2015 at 8:39 AM, Markus Heller hel...@relix.de mailto:hel...@relix.de wrote: Dear list, I'd like to understand how to receive the 2m band as one wideband input (144-146 MHz) and afterwards split the sample stream into various channels (relay inputs, relay outputs for various relay frequencies). I do know how to receive all of the 2m band, but I don't know how to do the splitting. How would I do that? Thanks in advance! br markus dl8rds ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org mailto:Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
A simple way in GNURadio is to use the frequency xlating fir filter to select individual channels. On Tue, Jul 21, 2015 at 8:39 AM, Markus Heller hel...@relix.de wrote: Dear list, I'd like to understand how to receive the 2m band as one wideband input (144-146 MHz) and afterwards split the sample stream into various channels (relay inputs, relay outputs for various relay frequencies). I do know how to receive all of the 2m band, but I don't know how to do the splitting. How would I do that? Thanks in advance! br markus dl8rds ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] isolate channels from wideband
Dear list, I'd like to understand how to receive the 2m band as one wideband input (144-146 MHz) and afterwards split the sample stream into various channels (relay inputs, relay outputs for various relay frequencies). I do know how to receive all of the 2m band, but I don't know how to do the splitting. How would I do that? Thanks in advance! br markus dl8rds ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
I would add, this task you are trying to do is an advanced DSP topic. What you're looking for is a channelizer and this is optimally implemented using a polyphase filter bank. If you need a good reference on this, fred harris' book on Multirate Signal Processing for Comms Systems is a good. http://www.amazon.com/Multirate-Signal-Processing-Communication-Systems/dp/0131465112 GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. Rich On Tue, Jul 21, 2015 at 9:17 AM, Martin Braun martin.br...@ettus.com wrote: Or, given a regular channel spacing, you can use a polyphase filterbank to split it into multiple narrow-band channels. Cheers, Martin On 21.07.2015 09:10, Stephen Harrison wrote: A simple way in GNURadio is to use the frequency xlating fir filter to select individual channels. On Tue, Jul 21, 2015 at 8:39 AM, Markus Heller hel...@relix.de mailto:hel...@relix.de wrote: Dear list, I'd like to understand how to receive the 2m band as one wideband input (144-146 MHz) and afterwards split the sample stream into various channels (relay inputs, relay outputs for various relay frequencies). I do know how to receive all of the 2m band, but I don't know how to do the splitting. How would I do that? Thanks in advance! br markus dl8rds ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org mailto:Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
I use the PFB channelizer for incoherent de-dispersion for pulsar monitoring in radio astronomy. It's quite efficient for producing N equally-spaced channels. For randomly-spaced, individual frequency-xlating FFT filters might be better. On 2015-07-21 13:51, Richard Bell wrote: I would add, this task you are trying to do is an advanced DSP topic. What you're looking for is a channelizer and this is optimally implemented using a polyphase filter bank. If you need a good reference on this, fred harris' book on Multirate Signal Processing for Comms Systems is a good. http://www.amazon.com/Multirate-Signal-Processing-Communication-Systems/dp/0131465112 [3] GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. Rich On Tue, Jul 21, 2015 at 9:17 AM, Martin Braun martin.br...@ettus.com wrote: Or, given a regular channel spacing, you can use a polyphase filterbank to split it into multiple narrow-band channels. Cheers, Martin On 21.07.2015 09 [1]:10, Stephen Harrison wrote: A simple way in GNURadio is to use the frequency xlating fir filter to select individual channels. On Tue, Jul 21, 2015 at 8:39 AM, Markus Heller hel...@relix.de mailto:hel...@relix.de wrote: Dear list, I'd like to understand how to receive the 2m band as one wideband input (144-146 MHz) and afterwards split the sample stream into various channels (relay inputs, relay outputs for various relay frequencies). I do know how to receive all of the 2m band, but I don't know how to do the splitting. How would I do that? Thanks in advance! br markus dl8rds ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org mailto:Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio [2] ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio [2] ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio [2] ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio [2] Links: -- [1] tel:21.07.2015%2009 [2] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio [3] http://www.amazon.com/Multirate-Signal-Processing-Communication-Systems/dp/0131465112___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
I agree an illustrated example would be extremely useful to all of us. Rich On Tue, Jul 21, 2015 at 12:00 PM, Marcus Müller marcus.muel...@ettus.com wrote: That would be extremely awesome. Especially for people with some DSP filter experience, the Polyphase filterbanks are somewhat hard to understand, and I think Tom's article / presentation (which I can't seem to find right now) on the PFBs can only profit from a real-world example accompanying their message. --Marcus On 21.07.2015 20:56, Chris Kuethe wrote: Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough). Now you get a long filter. Copy and paste the filter coefficients from gr_filter_design to your PFB filter taps property. Set your channelizers number of channels according to your plans -- 40, if you want to get all the 40 25kHz channels in 2MHz. You get a block with 40 outputs! Explaining things like channel mapping is best done by pointing you at the official documentation: [3] Greetings! Marcus [1] Hamming is not always the best choice, I'd try that, Blackman-harris, and Kaiser. I personally like harris in this case -- we want to get a full channel, two adjacent channels are usually not occupied, and as soon as we pass the stopband frequency, we're basically at -100dB. [2] assuming you want to use 2MS/s for your 2MHz wide band, 2MHz sampling rate, and assuming 25kHz wide channels, 12.5kHz cut off frequency, 25kHz start of stoppband. I get something like 440 taps. [3] https://gnuradio.org/doc/doxygen/classgr_1_1filter_1_1pfb__channelizer__ccf.html ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
On Tue, Jul 21, 2015 at 3:00 PM, Marcus Müller marcus.muel...@ettus.com wrote: That would be extremely awesome. Especially for people with some DSP filter experience, the Polyphase filterbanks are somewhat hard to understand, and I think Tom's article / presentation (which I can't seem to find right now) on the PFBs can only profit from a real-world example accompanying their message. --Marcus Here's my presentation from last GRCon: http://gnuradio.squarespace.com/grcon14-presentations#tut-rondeau I can't find a link anywhere to the WSR'14 papers/presentations. I'll need to put that on my website and the gnuradio.org Academic Papers page sometime. Tom On 21.07.2015 20:56, Chris Kuethe wrote: Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough). Now you get a long filter. Copy and paste the filter coefficients from gr_filter_design to your PFB filter taps property. Set your channelizers number of channels according to your plans -- 40, if you want to get all the 40 25kHz channels in 2MHz. You get a block with 40 outputs! Explaining things like channel mapping is best done by pointing you at the official documentation: [3] Greetings! Marcus [1] Hamming is not always the best choice, I'd try that, Blackman-harris, and Kaiser. I personally like harris in this case -- we want to get a full channel, two adjacent channels are usually not occupied, and as soon as we pass the stopband frequency, we're basically at -100dB. [2] assuming you want to use 2MS/s for your 2MHz wide band, 2MHz sampling rate, and assuming 25kHz wide channels, 12.5kHz cut off frequency, 25kHz start of stoppband. I get something like 440 taps. [3] https://gnuradio.org/doc/doxygen/classgr_1_1filter_1_1pfb__channelizer__ccf.html ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough). Now you get a long filter. Copy and paste the filter coefficients from gr_filter_design to your PFB filter taps property. Set your channelizers number of channels according to your plans -- 40, if you want to get all the 40 25kHz channels in 2MHz. You get a block with 40 outputs! Explaining things like channel mapping is best done by pointing you at the official documentation: [3 [1]] Greetings! Marcus [1] Hamming is not always the best choice, I'd try that, Blackman-harris, and Kaiser. I personally like harris in this case -- we want to get a full channel, two adjacent channels are usually not occupied, and as soon as we pass the stopband frequency, we're basically at -100dB. [2] assuming you want to use 2MS/s for your 2MHz wide band, 2MHz sampling rate, and assuming 25kHz wide channels, 12.5kHz cut off frequency, 25kHz start of stoppband. I get something like 440 taps. [3] https://gnuradio.org/doc/doxygen/classgr_1_1filter_1_1pfb__channelizer__ccf.html [1] ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio [2] Links: -- [1] https://gnuradio.org/doc/doxygen/classgr_1_1filter_1_1pfb__channelizer__ccf.html [2] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
That would be extremely awesome. Especially for people with some DSP filter experience, the Polyphase filterbanks are somewhat hard to understand, and I think Tom's article / presentation (which I can't seem to find right now) on the PFBs can only profit from a real-world example accompanying their message. --Marcus On 21.07.2015 20:56, Chris Kuethe wrote: Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough). Now you get a long filter. Copy and paste the filter coefficients from gr_filter_design to your PFB filter taps property. Set your channelizers number of channels according to your plans -- 40, if you want to get all the 40 25kHz channels in 2MHz. You get a block with 40 outputs! Explaining things like channel mapping is best done by pointing you at the official documentation: [3] Greetings! Marcus [1] Hamming is not always the best choice, I'd try that, Blackman-harris, and Kaiser. I personally like harris in this case -- we want to get a full channel, two adjacent channels are usually not occupied, and as soon as we pass the stopband frequency, we're basically at -100dB. [2] assuming you want to use 2MS/s for your 2MHz wide band, 2MHz sampling rate, and assuming 25kHz wide channels, 12.5kHz cut off frequency, 25kHz start of stoppband. I get something like 440 taps. [3] https://gnuradio.org/doc/doxygen/classgr_1_1filter_1_1pfb__channelizer__ccf.html ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
Hi Rich, hello Markus, On 21.07.2015 19:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough). Now you get a long filter. Copy and paste the filter coefficients from gr_filter_design to your PFB filter taps property. Set your channelizers number of channels according to your plans -- 40, if you want to get all the 40 25kHz channels in 2MHz. You get a block with 40 outputs! Explaining things like channel mapping is best done by pointing you at the official documentation: [3] Greetings! Marcus [1] Hamming is not always the best choice, I'd try that, Blackman-harris, and Kaiser. I personally like harris in this case -- we want to get a full channel, two adjacent channels are usually not occupied, and as soon as we pass the stopband frequency, we're basically at -100dB. [2] assuming you want to use 2MS/s for your 2MHz wide band, 2MHz sampling rate, and assuming 25kHz wide channels, 12.5kHz cut off frequency, 25kHz start of stoppband. I get something like 440 taps. [3] https://gnuradio.org/doc/doxygen/classgr_1_1filter_1_1pfb__channelizer__ccf.html ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] isolate channels from wideband
Maybe I'll do up an illustrated example on this using NOAA weather radio, or the pager band On Tue, Jul 21, 2015 at 11:42 AM, mle...@ripnet.com wrote: I just use the built-in firdes stuff, rather than using an external designer. On 2015-07-21 14:38, Marcus Müller wrote: Hi Rich, hello Markus, On 21.07.2015 19:51, Richard Bell wrote: GNU Radio has channelizers built-in, but I've not used them yet, so I don't know how far they take you into this kind of task. the Polyphase channelizer is actually an implementation derived from that school of thought, and it works amazingly well. In fact, in preparation of a presentation at a certain ham conference, I tried using it to get 20 PMR/LPD channels out of a 1MS/s signal in real time, and then just shuffle them around, before feeding them back into the inverse synthesizer PFB. It's pretty easy: Design a single low pass filter, as if you just wanted to filter out the channel which is centered exactly at your RF center frequency, i.e. 0Hz, with the full sampling rate [2], using the gr_filter_design tool. Play around with the different window types[1], and bear in mind that the suppression outside your desired passband needs to be high enough so that the sum of the energy in all other channels don't hurt your channel too much, but don't overdo it (60dB suppression should be enough). Now you get a long filter. Copy and paste the filter coefficients from gr_filter_design to your PFB filter taps property. Set your channelizers number of channels according to your plans -- 40, if you want to get all the 40 25kHz channels in 2MHz. You get a block with 40 outputs! Explaining things like channel mapping is best done by pointing you at the official documentation: [3] Greetings! Marcus [1] Hamming is not always the best choice, I'd try that, Blackman-harris, and Kaiser. I personally like harris in this case -- we want to get a full channel, two adjacent channels are usually not occupied, and as soon as we pass the stopband frequency, we're basically at -100dB. [2] assuming you want to use 2MS/s for your 2MHz wide band, 2MHz sampling rate, and assuming 25kHz wide channels, 12.5kHz cut off frequency, 25kHz start of stoppband. I get something like 440 taps. [3] https://gnuradio.org/doc/doxygen/classgr_1_1filter_1_1pfb__channelizer__ccf.html ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ 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? ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
