On 06/18/2020 07:27 AM, Jeff Long
wrote:
Ah, it's a Python heir block. You could reduce the
quadrature rate further so that the quadrature rate is closer to
200 kS/s and/or put a 200 kHz LPF in front of the block. There's
internal filtering for the various components of the baseband
signal, but no internal filtering before the PLL. It could also
be just that FM stereo is more sensitive to noise (try GQRX
stereo on a station that sounds good in mono).
FM stereo is notoriously sensitive to multi-path, which can make a
signal that sounds really good in mono sound like crap in stereo.
If there's no filter inside "WBFM Receive PLL", place
one before it. The example in gr-uhd has a 400 kHz filter
there.
Hi,
I have a broadcast FM (mono) receiver which works well,
with good audio
and clean traces in the Time Domain. See
https://wiki.gnuradio.org/index.php/File:USRP_FM_fg.png
Then I made a stereo version. See
https://wiki.gnuradio.org/index.php/File:USRP_FM_stereo_fg.png
Using
it, the sound has a distortion but does not have any audio
underruns.
The traces in the Time Domain have a lot of "fuzz"
(noise?).
Do I need a filter? If so, would it come before or after
the WBFM
Receive PLL block?
Once I have a good design, I will use it as an Example
Flowgraph.
Thanks for your help.
--
Barry Duggan KV4FV
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