On 01/14/2015 12:44 PM, Chris Hallinan wrote:
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
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
--
Life is like Linux - it never stands still.
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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.
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
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