RTL-SDR and Raspberry Pi - Choppy Audio with rtl_fm

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Straussberg

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Howdy! I'm new to both RTL-SDR and setting up a scanner provider. I've been following the instructions on the RR Wiki, Raspberry Pi RTL-SDR Broadcastify - The RadioReference Wiki and wanted to ensure the setup was working before I started the feed. As such, I've tried piping the rtl_fm feed to both the speakers and a test icecast server I've setup, and no matter the settings, it seems to have very choppy audio. Could this be my RTL-SDR, or the 1st gen Raspberry Pi I'm using? I have a few extra laptops and radios lying around so I'm sure I could get something working, but I'd like to use the RTL-SDR if possible.

Thanks!
 

aaknitt

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Aug 27, 2005
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Howdy! I'm new to both RTL-SDR and setting up a scanner provider. I've been following the instructions on the RR Wiki, Raspberry Pi RTL-SDR Broadcastify - The RadioReference Wiki and wanted to ensure the setup was working before I started the feed. As such, I've tried piping the rtl_fm feed to both the speakers and a test icecast server I've setup, and no matter the settings, it seems to have very choppy audio. Could this be my RTL-SDR, or the 1st gen Raspberry Pi I'm using? I have a few extra laptops and radios lying around so I'm sure I could get something working, but I'd like to use the RTL-SDR if possible.

Thanks!
I've had trouble with this as well even on a RPi 3. I can't say I've found a great solution. My experience has been that the squelch setting seems to be the culprit. I've found that in order to get decent audio I need to pretty much run open squelch, which doesn't work well for anything that's not a broadcast station. Here are the settings I've used to receive NOAA weather radio with decent (non-choppy) audio:

Code:
rtl_fm -M fm -s 11025 -f 162.4M -p 47 | play -r 11025 -t raw -e s -b 16 -c 1 -V1 -
Andy
 

Straussberg

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Location
Virginia
Thanks for that; that seems to be what I've experienced this week. Is there no support for PL and DPL squelch for rtl_fm?
 
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