# First time user - fm radio tutorial has choppy audio **URL:** \ **Category:** GNU Radio\ **Created:** [January 14, 2015, 6:45pm UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815 "2015-01-14T18:45:27Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\ **Post date:** [January 14, 2015, 6:45pm UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/1 "2015-01-14T18:45:27Z")
Greetings, I’m a first time user of gnuradio. Kudos to the developers, it only took me about a day to build gnuradio + gr-osmosdr (for my el-cheapo rtl2832 dongle) from source, including getting a basic FM broadcast receiver sort-of running. Host Ubuntu 14.04 on a very fast Dell 8-core server platform. I’ve prototyped an FM receiver as described in the tutorial at the bottom of this page: [http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided\_Tutorial\_Hardware\_Considerations](http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorial_Hardware_Considerations) However, when I run it, and set the center frequency to a close-by FM station, although I can hear actual broadcast audio snippets, meaning that it’s actually receiving a coherent signal, it is very choppy, with audio snippets being played in a very choppy, almost rhythmic fashion. The console window on gnuradio-companion shows a continuous series of aUaUaU, etc. I’m guessing this might be an underrun situation somewhere, but that is speculation. I’m using parameters provided by the tutorial including a sample rate 250K. I’ve tried moving the sample rate around, but without much improvement. Dropping it down significantly destroys all hints of intelligence in the signal 😉 Am I overtaxing the capabilities of this rtl-sdr dongle? I have a reasonable (and growing) understand of the core concepts, but could use some help on the learning curve. Any advice appreciated. -Chris ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 14, 2015, 6:55pm UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/2 "2015-01-14T18:55:09Z")
On 01/14/2015 12:44 PM, Chris H.inan wrote: > However, when I run it, and set the center frequency to a close-by FM > destroys all hints of intelligence in the signal 😉 Am I overtaxing > > – > Life is like Linux - it never stands still. > > * * * > > Discuss-gnuradio mailing list > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) > You almost certainly have a sample-rate mismatch somewhere in the > flow–likely, your audio sink is configured for a sample-rate other than > what > the hardware (or PulseAudio) can support. Sometimes also, PulseAudio > gets into trouble and gets all under-runny. I’d go with Alsa direct if > it > were my problem, and skip Pulse entirely. ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 14, 2015, 6:54pm UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/3 "2015-01-14T18:54:33Z")
Hi Chris, On 01/14/2015 06:44 PM, Chris H.inan wrote: > Greetings, I’m a first time user of gnuradio. > Welcome! > > I’m guessing this might be an underrun situation somewhere, but that > is speculation. > But speculation that’s probably correct 🙂 > aU is audio underrun, which means you’re most probably supplying samples > at a rate that’s lower than the audio sink is configured to accept. > I’m using parameters provided by the tutorial including a sample rate > 250K. I’ve tried moving the sample rate around, but without much > improvement. Dropping it down significantly destroys all hints of > intelligence in the signal 😉 Am I overtaxing the capabilities of > this rtl-sdr dongle? > Probably not, since you’re doing so well this far! Basically, use a > sampling rate that works, and decimate to exactly the sampling rate you > need for your audio sink. > I have a reasonable (and growing) understand of the core concepts, but > could use some help on the learning curve. > > Any advice appreciated. see above 🙂 Greetings, and happy hacking, Marcus ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 14, 2015, 7:09pm UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/4 "2015-01-14T19:09:44Z")
On Wed, Jan 14, 2015 at 12:53 PM, Marcus D. Leech [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > speculation. I’m using parameters provided by the tutorial including a > -Chris > You almost certainly have a sample-rate mismatch somewhere in the > Principal Investigator > Shirleys Bay Radio Astronomy Consortiumhttp://www.sbrac.org The manual gives you a few hints for different possible device names you can try: > **[GNU Radio Manual and C++ API Reference: gr::audio::sink Class Reference](https://www.gnuradio.org/doc/doxygen/classgr_1_1audio_1_1sink.html)** Unlike Marcus, I’ve always had better luck with pulse that direct alsa. But we have very different systems and use different Linux versions, so ymmv. Tom ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 15, 2015, 5:29am UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/5 "2015-01-15T05:29:59Z")
Hi, How would I change this, skipping PulseAudio and using Alsa? The only audio application I try with gnuradio at the moment behaves similar here. I try to decode DMR, and I get choppy audio although everything should be OK. I blamed gr-dsd, but maybe it is a common issue. Will have to try a simple FM RX to verify 🙂 Ralph. ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 15, 2015, 5:33am UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/6 "2015-01-15T05:33:39Z")
On 01/14/2015 11:28 PM, Ralph A. Schmid, dk5ras wrote: > Hi, > > How would I change this, skipping PulseAudio and using Alsa? The only audio > application I try with gnuradio at the moment behaves similar here. I try to > decode DMR, and I get choppy audio although everything should be OK. I blamed > gr-dsd, but maybe it is a common issue. Will have to try a simple FM RX to verify > 🙂 > > Ralph. > > > You almost certainly have a sample-rate mismatch somewhere in the flow–likely, > > your audio sink is configured for a sample-rate other than what > > the hardware (or PulseAudio) can support. Sometimes also, PulseAudio gets into > > trouble and gets all under-runny. I’d go with Alsa direct if it > > were my problem, and skip Pulse entirely. One could just try dial\_tone.py example. That will exercise the audio subsystem. For alsa, in the device field in the audio sink, try something like hw:0,0 or plughw:0,0 ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 15, 2015, 6:30am UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/7 "2015-01-15T06:30:53Z")
> One could just try dial\_tone.py example. That will exercise the audio subsystem. Output is some garbled noise, and python$ python dial\_tone.py INFO: Audio sink arch: alsa aUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaU So my audio stuff is defective, good to know 🙂 > For alsa, in the device field in the audio sink, try something like > hw:0,0 or plughw:0,0 Seems to be alsa already…hmm…so this comes later. Ralph. ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 15, 2015, 6:41am UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/8 "2015-01-15T06:41:51Z")
On 01/15/2015 12:29 AM, Ralph A. Schmid, dk5ras wrote: > > hw:0,0 or plughw:0,0 > > Seems to be alsa already…hmm…so this comes later. > > Ralph. It may just be that your audio-subsystem doesn’t actually support the sample-rate that the graph is configuring it for. Here’s the --help for dial\_tone.py Usage: dial\_tone.py [options] Options: -h, --help show this help message and exit -O AUDIO\_OUTPUT, --audio-output=AUDIO\_OUTPUT pcm output device name. E.g., hw:0,0 or /dev/dsp -r SAMPLE\_RATE, --sample-rate=SAMPLE\_RATE set sample rate to RATE (48000) Looks like the default is 48e3 Try other rates, like 44.1e3 or 32e3 ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 15, 2015, 6:50am UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/9 "2015-01-15T06:50:22Z")
> It may just be that your audio-subsystem doesn’t actually support the sample-rate > that the graph is configuring it for. Maybe. At least the test audio from the audio control panel is clear. > Here’s the --help for dial\_tone.py > Usage: dial\_tone.py [options] > Options: > -h, --help show this help message and exit > -O AUDIO\_OUTPUT, --audio-output=AUDIO\_OUTPUT > pcm output device name. E.g., hw:0,0 or > /dev/dsp > -r SAMPLE\_RATE, --sample-rate=SAMPLE\_RATE > set sample rate to RATE (48000) > Looks like the default is 48e3 > Try other rates, like 44.1e3 or 32e3 I will test it and tell you 🙂 Ralph. ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 15, 2015, 7:17am UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/10 "2015-01-15T07:17:11Z")
Only 44100 works, giving a clear dial tone. As DSD has fixed sampling rate 8k, a resampler should do the trick. Things could be so easy 🙂 I hate this audio stuff… Ralph. ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 15, 2015, 7:22am UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/11 "2015-01-15T07:22:40Z")
On 01/15/2015 01:15 AM, Ralph A. Schmid, dk5ras wrote: > Only 44100 works, giving a clear dial tone. As DSD has fixed sampling rate 8k, a > resampler should do the trick. Things could be so easy 🙂 I hate this audio > stuff… > > Ralph. > If you use “plughw:0,0” as the hardware designator, it’s often willing > to do resampling to the actual hardware rate. ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 15, 2015, 8:15am UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/12 "2015-01-15T08:15:44Z")
Hi Marcus, > If you use “plughw:0,0” as the hardware designator, it’s often willing to do > resampling to the actual hardware rate. Yep, I will try this later. Made my tests this morning on my way to work by train, now it has to wait until lunch break 🙂 Ralph. ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 15, 2015, 1:48pm UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/13 "2015-01-15T13:48:53Z")
No chance, I do not get any stable audio performance, I assume the Kubuntu sound system is defective somehow. It is not about sampling rates, the pitch is correct, just choppy. When calling the dial tone script repeatedly, sometimes it works, sometimes it causes garbled sounds, then again it works, with one attempt after another without doing anything else. Update: Right now I was so brave to uninstall some pulse library stuff, and what should I say, the stuttering is gone, DMR is not decoding 100% fine, but I assume now it is a matter of fine tuning the receiver chain and decoder, audio itself looks OK. Thank you very much for putting me into the right direction! How can find such a load of BS its way into an official and widely used Linux distribution?! Ralph. > -----Original Message----- > From: [discuss-gnuradio-bounces+ralph=removed\_email\_address@domain.invalid](mailto:discuss-gnuradio-bounces+ralph=removed_email_address@domain.invalid) > [[mailto:discuss-gnuradio-bounces+ralph=removed\_email\_address@domain.invalid](mailto:discuss-gnuradio-bounces+ralph=removed_email_address@domain.invalid)] On Behalf Of > Ralph A. Schmid, dk5ras > Sent: Thursday, January 15, 2015 8:14 AM > To: ‘Marcus D. Leech’; ‘Tom R.’ > Cc: ‘GNURadio D.ion List’ > Subject: Re: [Discuss-gnuradio] First time user - fm radio tutorial has > choppy > audio > > Hi Marcus, > > > If you use “plughw:0,0” as the hardware designator, it’s often willing > > to do resampling to the actual hardware rate. > > Yep, I will try this later. Made my tests this morning on my way to work > by ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 15, 2015, 10:39pm UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/14 "2015-01-15T22:39:22Z")
Hi, I had this same aU problem a few months ago on Linux Mint, but was able to resolve it by editing the default ALSA settings in ~/.gnuradio/config.conf . I will send detailed notes on the exact fix I made when I get home, but I just found this page also describing the fix: [http://www.funwithelectronics.com/?id=167](http://www.funwithelectronics.com/?id=167) (Increase ‘nperiods’ under [audio\_alsa]) After the config change ALSA audio worked with my own WBFM flowgraph and all the sample flowgraphs that were previously broken for me. Apologies for not sending something to the list when I found the problem. I knew it would have saved folks from some hair pulling. Hope this helps, -Remington W7REM On Thu, Jan 15, 2015 at 4:47 AM, Ralph A. Schmid, dk5ras [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 16, 2015, 5:43am UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/15 "2015-01-16T05:43:02Z")
Ok, here are the contents of my ~/.gnuradio/config.conf: [audio\_alsa] default\_input\_device = default default\_output\_device = default #period\_time = 0.010 # in seconds (default) period\_time = 0.100 # in seconds nperiods = 4 # total buffering = period\_time \* nperiods #verbose = false verbose = true The actual change I made was to increase audio\_alsa/period\_time from 0.010 to 0.100. Play around with it until it works on your system. My only guess is that perhaps the default ALSA buffer sizes are small enough that they are often consumed by ALSA before GnuRadio will fill them. Cheers, -Remington PS. Thanks to everyone for your fantastic work on building this whole system and answering all the questions on the list. I’ve been learning a ton reading this over the last year, and I appreciate it. I’ll try not to be so shy next time I know something that might be useful to others. On Thu, Jan 15, 2015 at 1:38 PM, Remington F. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 16, 2015, 8:25pm UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/16 "2015-01-16T20:25:06Z")
On Thu, Jan 15, 2015 at 11:42 PM, Remington F. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > The actual change I made was to increase audio\_alsa/period\_time from 0.010 > to 0.100. Play around with it until it works on your system. My only > guess is that perhaps the default ALSA buffer sizes are small enough that > they are often consumed by ALSA before GnuRadio will fill them. Ah ha! Thanks, Remington. That was my issue. My first clue should have been that I was hearing intelligible signal, even though very choppy. That alone suggest that my flow graph was properly configured with respect to sampling rates, rate conversion (resampling), etc. Your settings did not work directly on my system (almost stock Ubuntu 14.04) , but improved my situation significantly. After trying your settings, I got proper sound for about .5 seconds, followed by perhaps a quarter second of dropout. Playing around, I got smooth audio using these settings: period\_time = 0.400 nperiods = 16 I guess I’m gonna have to learn more about ALSA than I ever wanted to! Thanks much! -Chris ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [January 16, 2015, 11:38am UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/17 "2015-01-16T11:38:40Z")
Good to know! In my case it was a pulse issue, and removing parts of this stuff fixed it, but who know what else may happen 🙂 At least now gr-dsd works, I can decode DMR transmissions with it in relative good quality, and also other audio applications should cause no trouble. Not that I do very much audio stuff, for receiving audio usually I use Windows / HDSDR. And I only can second your “thanks guys” message. Great work, gnuradio is a fantastic tool that opens whole new worlds! Ralph. From: Remington F. [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] Sent: Friday, January 16, 2015 5:42 AM To: Ralph A. Schmid, dk5ras Cc: Marcus D. Leech; Tom R.; Christopher Hallinan; GNURadio Discussion L. Subject: Re: [Discuss-gnuradio] First time user - fm radio tutorial has choppy audio Ok, here are the contents of my ~/.gnuradio/config.conf: [audio\_alsa] default\_input\_device = default default\_output\_device = default #period\_time = 0.010 # in seconds (default) period\_time = 0.100 # in seconds nperiods = 4 # total buffering = period\_time \* nperiods #verbose = false verbose = true The actual change I made was to increase audio\_alsa/period\_time from 0.010 to 0.100. Play around with it until it works on your system. My only guess is that perhaps the default ALSA buffer sizes are small enough that they are often consumed by ALSA before GnuRadio will fill them. Cheers, -Remington PS. Thanks to everyone for your fantastic work on building this whole system and answering all the questions on the list. I’ve been learning a ton reading this over the last year, and I appreciate it. I’ll try not to be so shy next time I know something that might be useful to others. On Thu, Jan 15, 2015 at 1:38 PM, Remington F. \<[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) [mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) \> wrote: Hi, I had this same aU problem a few months ago on Linux Mint, but was able to resolve it by editing the default ALSA settings in ~/.gnuradio/config.conf . I will send detailed notes on the exact fix I made when I get home, but I just found this page also describing the fix: > **[Choppy sound with GNU Radio and PulseAudio - Fun With Electronics](https://www.funwithelectronics.com/?id=167)** (Increase ‘nperiods’ under [audio\_alsa]) After the config change ALSA audio worked with my own WBFM flowgraph and all the sample flowgraphs that were previously broken for me. Apologies for not sending something to the list when I found the problem. I knew it would have saved folks from some hair pulling. Hope this helps, -Remington W7REM On Thu, Jan 15, 2015 at 4:47 AM, Ralph A. Schmid, dk5ras \<[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) [mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) \> wrote: No chance, I do not get any stable audio performance, I assume the Kubuntu sound system is defective somehow. It is not about sampling rates, the pitch is correct, just choppy. When calling the dial tone script repeatedly, sometimes it works, sometimes it causes garbled sounds, then again it works, with one attempt after another without doing anything else. Update: Right now I was so brave to uninstall some pulse library stuff, and what should I say, the stuttering is gone, DMR is not decoding 100% fine, but I assume now it is a matter of fine tuning the receiver chain and decoder, audio itself looks OK. Thank you very much for putting me into the right direction! How can find such a load of BS its way into an official and widely used Linux distribution?! Ralph. > -----Original Message----- > From: [discuss-gnuradio-bounces+ralph=removed\_email\_address@domain.invalid](mailto:discuss-gnuradio-bounces+ralph=removed_email_address@domain.invalid) > [mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [mailto:discuss-gnuradio-bounces+ralph [mailto:discuss-gnuradio-bounces%2Bralph](mailto:discuss-gnuradio-bounces%2Bralph) > =removed\_email\_address@domain.invalid [mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ] On Behalf Of > Ralph A. Schmid, dk5ras > Sent: Thursday, January 15, 2015 8:14 AM > To: ‘Marcus D. Leech’; ‘Tom R.’ > Cc: ‘GNURadio D.ion List’ > Subject: Re: [Discuss-gnuradio] First time user - fm radio tutorial has > choppy > audio > Hi Marcus, > > > If you use “plughw:0,0” as the hardware designator, it’s often willing > > to do resampling to the actual hardware rate. > > Yep, I will try this later. Made my tests this morning on my way to work > by ---
**Author:** ![Chris\_H.inan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@Chris\_H.inan](https://www.ruby-forum.com/u/Chris_H.inan)\ **Post date:** [May 11, 2016, 6:46am UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/18 "2016-05-11T06:46:41Z")
Chris H.inan wrote in post #1166653: > Greetings, I’m a first time user of gnuradio. Kudos to the developers, > it > only took me about a day to build gnuradio + gr-osmosdr (for my > el-cheapo > rtl2832 dongle) from source, including getting a basic FM broadcast > receiver sort-of running. Host Ubuntu 14.04 on a very fast Dell > 8-core server platform. > > I’ve prototyped an FM receiver as described in the tutorial at the > bottom > of this page: [http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided\_Tutorial\_Hardware\_Considerations](http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorial_Hardware_Considerations) > However, when I run it, and set the center frequency to a close-by FM > station, although I can hear actual broadcast audio snippets, meaning > that > it’s actually receiving a coherent signal, it is very choppy, with audio > snippets being played in a very choppy, almost rhythmic fashion. The > console window on gnuradio-companion shows a continuous series of > aUaUaU, > etc. > > I’m guessing this might be an underrun situation somewhere, but that is > speculation. I’m using parameters provided by the tutorial including a > sample rate 250K. I’ve tried moving the sample rate around, but without > much improvement. Dropping it down significantly destroys all hints of > intelligence in the signal 😉 Am I overtaxing the capabilities of this > rtl-sdr dongle? > > I have a reasonable (and growing) understand of the core concepts, but > could use some help on the learning curve. > > Any advice appreciated. > > -Chris Hi Chris, Sorry to ask out of contents question but may I ask which way you chose to install the Gnu Radio from source? did you use Pybombs? regards, Shahnaz ---
**Author:** ![rolf](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/94ad74/32.png) [@rolf](https://www.ruby-forum.com/u/rolf)\ **Post date:** [November 21, 2018, 9:05am UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/19 "2018-11-21T09:05:14Z")
I had the same problem and disabling PulseAudio in combination with the previously mentioned change in ALSA config worked for me: [https://kodi.wiki/view/PulseAudio/HOW-TO:\_](https://kodi.wiki/view/PulseAudio/HOW-TO:_) Disable\_PulseAudio\_and\_use\_ALSA\_(without\_removing\_PulseAudio)\_for\_Ubuntu Works fine now. Im having issues with adding the link. Just copy paste the whole thing. -Rolf ---
**Author:** ![voyalgru](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/ed655f/32.png) [@voyalgru](https://www.ruby-forum.com/u/voyalgru)\ **Post date:** [February 23, 2020, 11:55am UTC](https://www.ruby-forum.com/t/first-time-user-fm-radio-tutorial-has-choppy-audio/233815/20 "2020-02-23T11:55:49Z")
can someone give me a step by step tutorial on how to do this… I’m new to linux, and new to gnu… everywhere I look everyone just says its easy you just have to edit the ~/.gnuradio/config.conf I don’t have enough information too even know what to look for. How and what files do I copy and from where to edit or create the “fix”??? please make it simple ex… - hit “alt+t” or “ctrl+alt+t” to open a command line window. - type sudo (insert junk here) - then you’ll want to (more junk with juicy details) - now you can type… [audio\_alsa] nperiods = 16 period\_time = 0.100 … I would appreciate it, thank you