Re: Resource issues when trying to record 2 FM broadcast
On 20/05/2023 09:12, Martin Lefkowitz wrote: Here is the screen capture of the Marcus Leech version of the two FM demodulate as described here https://wiki.gnuradio.org/index.php?title=Frequency_Xlating_FIR_Filter https://github.com/patchvonbraun/wfm_stuff With a samplerate of 2.4M it uses about 60% of the 4 core I5 I am using for this project If anybody wants the grc pm me. The other email contains the Zans version of stereo demod. Your taps for the freq-xlating filters aren't properly specified. They must be the output of one of the taps-generator functions--use the Low Pass Filter Taps block. Further, your desired parameters will lead to a very large filter. This is mostly controlled by the transition width parameter, and as that parameter becomes a smaller fraction of the sample-rate, the filter grows non-linearly. Consider a "lazier" transition width, and use an FFT filter instead--the FFT filter structure is more efficient once you have more than perhaps 30-50 taps. I haven't touched the "wfm_stuff" code in a long long time, so no guarantees about anything--including performance.
Re: Resource issues when trying to record 2 FM broadcast
Here is the screen capture of the Marcus Leech version of the two FM demodulate as described here https://wiki.gnuradio.org/index.php?title=Frequency_Xlating_FIR_Filter https://github.com/patchvonbraun/wfm_stuff With a samplerate of 2.4M it uses about 60% of the 4 core I5 I am using for this project If anybody wants the grc pm me. The other email contains the Zans version of stereo demod. 2fmtopblock.pdf Description: Adobe PDF document wfm_stereo-heir.pdf Description: Adobe PDF document
Re: Resource issues when trying to record 2 FM broadcast
Trying screen capture. This email will contain the zans FM demod version of receiving 2 broadcast radio stations. based on the project referenced here http://zansprojects.blogspot.com/2019/05/stereo-fm-receiving-with-rtl-sdr-and_23.html https://forums.radioreference.com/threads/multiple-fm-station-receiver.341340/#lg=_xfUid-2-1556650274=0 At 1024Mhz sample rate I was getting about 89% on my 4 core I5. If I went much higher both the wav file and the audio out would glitch. The other message will contain the Marcus Leech version FM_Demod_heir.pdf Description: Adobe PDF document TwoFMDemod.pdf Description: Adobe PDF document
Re: Resource issues when trying to record 2 FM broadcast
The list has absolutely no problems with JPEG images. We do have a file size limit, but what about you simply share the actual GRC flowgraph file instead of a screenshot of it? On 18.05.23 20:32, Martin Lefkowitz wrote: It looks like the list doesn't handle .jpg. i tried to post the images of my 2FM project to the list, but no images. Is there a spot to drop (image) files that is generally accepted on the list? Marty On 5/17/2023 5:23 PM, Gary Schafer wrote: "I can post the block diagrams if someone is interested." Yes, if you would, please. I'd be interested to see them and understand what it is you're trying to do. Thanks!
Re: Resource issues when trying to record 2 FM broadcast
It looks like the list doesn't handle .jpg. i tried to post the images of my 2FM project to the list, but no images. Is there a spot to drop (image) files that is generally accepted on the list? Marty On 5/17/2023 5:23 PM, Gary Schafer wrote: "I can post the block diagrams if someone is interested." Yes, if you would, please. I'd be interested to see them and understand what it is you're trying to do. Thanks!
Re: Resource issues when trying to record 2 FM broadcast
"I can post the block diagrams if someone is interested." Yes, if you would, please. I'd be interested to see them and understand what it is you're trying to do. Thanks!
Re: Resource issues when trying to record 2 FM broadcast
After reviewing your email, Marcus, I decided to go back to my original project with the Marcus Leech FM heir. I saw that ultimately the reason I stopped was that the Osomocom block (from the gunradio 3.7 project) was not sending signal. I could see this because the FFT graph directly connected to that output was blank. I was able to get the original project working by creating a new project adding a osomocom block then copying the rest of the blocks from the original project and it began working. At 2.4M sample rate it uses 50% of the CPU. The project with the FMDemod heir block is at 89% CPU usage at 1024M. Don't quite understand why but the old one works now and is more efficient. I can post the block diagrams if someone is interested.
Re: Resource issues when trying to record 2 FM broadcast stations
Hi Martin, On 13.05.23 17:40, Martin Lefkowitz wrote: I haven't spent a whole lot of time working with gnuradio. Well, then: Welcome to the GNU Radio community! I'm not a DSP engineer. I am however a software engineer that has dealt with signals so not completely a laymen, but I am out of my comfort zone. Let's rephrase this: Welcome to the GNU Radio community, the newly-found extension of your comfort zone ;) I had successfully created this project about 4 years ago using Marcus Leech's Stereo FM Radio implementation and grafting it into the front design of this the multiple station receiver design. Described here https://forums.radioreference.com/threads/multiple-fm-station-receiver.341340/#lg=_xfUid-2-1556650274=0 Looks fine :) You could have also absorbed the 1/4-resampler into the freq xlating FIR filter (by setting the decimation to 4), but the only benefit of that would have been slightly reduced computational load. For a bit of documentation on the Frequency XLating FIR Filter: https://wiki.gnuradio.org/index.php?title=Frequency_Xlating_FIR_Filter (the top right spectrum diagram I think explains quite nicely what I mean with "let the Xlating FIR filter also do the decimation" :) ) I recorded 2 pirate radio stations at a 4 day music festival. Started the recording on Thursday. Stopped it on Sunday. The sample rate was 2.4M. I created an Heir block that had the appropriate parts of Marcus Leech's Stereo FM radio in it. and replaced everything from the xlating FIR to the multiply const in the second block figure above with the heir block, and added some WXQT blocks to handle the gui for 2 stations like wav sinks, file names, etc. It was successful, but one thing that did happen was I needed to go from a Acer 720 (celeron) with Gallium installation to an (older) I5 laptop. I let that project sit for a couple of years. The first thing I did when I got back to it was upgrade everything. Big mistake... Nothing worked after that. Well, WX GUI was indeed removed a couple of years ago, as we had nobody that knew how to fix its bugs anymore. But for your purposes, Qt GUI should offer a drop-in replacement. The rest of the blocks should be the same as in the GNU Radio 3.7 era, no? I got grc 3.10 running with radioconda. I swapped Marcus's implementation out for Zan's fm_stereo_demod_clean https://forums.radioreference.com/threads/multiple-fm-station-receiver.341340/#lg=_xfUid-2-1556650274=0 http://zansprojects.blogspot.com/2019/05/stereo-fm-receiving-with-rtl-sdr-and.html In this new implementation I needed to create a series of variables to handle the design issue of having the signal be a multiple of 48k for the audio sink to be the correct speed. In particular the decimations in the rational resampler.This worked, but when I changed the sample rate to widen the bandwidth to receive 2 stations further apart on the FM band than 1Mhz I ran into performance issues. Basically with my setup the CPU load is about 90% with a sample rate of 1.24 Mhz. Could you really share your flow graph with us? This is a bit strange to understand by reading about modifications on a 3.7-era (so, obsolete) blog post of someone else - I'd much rather analyze your flow graph than someone else's :) I was able to do this because of the great work done by the people mentioned above, but figuring out how to deal with the performance issues is kind of beyond the disciplines I am familiar with. These sound likely to be caused by switching to that other flow graph and using inelegantly related sampling rates or filter bandwidths, but I can really only speculate without seeing your flow graph :) I am wondering if anybody has any suggestions on how to get fm_stereo_demod_clean to have better performance. I did not see an updated version of the Marcus Leech design so I figured there was something blocking that update, but maybe that is incorrect. Don't think so. All that might have happened is that Marcus (Leech, aka. the Marcus the Wiser) didn't have the time (or energy, or attention …) to port that. Matter of fact, we have a – hopefully sensibly working – example in our wiki of a single-station stereo FM receiver. Should work out of the box, no need to recreate Marcus L's hier block to get stereo: https://wiki.gnuradio.org/index.php?title=WBFM_Receive_PLL Combine that with your original Freq' Xlating FIR approach, and it *should* work :) I am also wondering if I could get a more powerful laptop/NUC and make it work with brute force by throwing money at the project. I would love to hear any suggestions from people with more grc and dsp experience, or which path I should take now. This should technically work on a slightly overprovisioned toaster microcontroller, so I don't think that'll be necessary :) Let's have a look at your flow graph together :) Best regards, Marcus
Resource issues when trying to record 2 FM broadcast stations
I haven't spent a whole lot of time working with gnuradio. I'm not a DSP engineer. I am however a software engineer that has dealt with signals so not completely a laymen, but I am out of my comfort zone. I had successfully created this project about 4 years ago using Marcus Leech's Stereo FM Radio implementation and grafting it into the front design of this the multiple station receiver design. Described here https://forums.radioreference.com/threads/multiple-fm-station-receiver.341340/#lg=_xfUid-2-1556650274=0 I recorded 2 pirate radio stations at a 4 day music festival. Started the recording on Thursday. Stopped it on Sunday. The sample rate was 2.4M. I created an Heir block that had the appropriate parts of Marcus Leech's Stereo FM radio in it. and replaced everything from the xlating FIR to the multiply const in the second block figure above with the heir block, and added some WXQT blocks to handle the gui for 2 stations like wav sinks, file names, etc. It was successful, but one thing that did happen was I needed to go from a Acer 720 (celeron) with Gallium installation to an (older) I5 laptop. I let that project sit for a couple of years. The first thing I did when I got back to it was upgrade everything. Big mistake... Nothing worked after that. I got grc 3.10 running with radioconda. I swapped Marcus's implementation out for Zan's fm_stereo_demod_clean https://forums.radioreference.com/threads/multiple-fm-station-receiver.341340/#lg=_xfUid-2-1556650274=0 http://zansprojects.blogspot.com/2019/05/stereo-fm-receiving-with-rtl-sdr-and.html In this new implementation I needed to create a series of variables to handle the design issue of having the signal be a multiple of 48k for the audio sink to be the correct speed. In particular the decimations in the rational resampler.This worked, but when I changed the sample rate to widen the bandwidth to receive 2 stations further apart on the FM band than 1Mhz I ran into performance issues. Basically with my setup the CPU load is about 90% with a sample rate of 1.24 Mhz. I was able to do this because of the great work done by the people mentioned above, but figuring out how to deal with the performance issues is kind of beyond the disciplines I am familiar with. I am wondering if anybody has any suggestions on how to get fm_stereo_demod_clean to have better performance. I did not see an updated version of the Marcus Leech design so I figured there was something blocking that update, but maybe that is incorrect. I am also wondering if I could get a more powerful laptop/NUC and make it work with brute force by throwing money at the project. I would love to hear any suggestions from people with more grc and dsp experience, or which path I should take now. Thanks in advance Marty
