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[Discuss-gnuradio] WBFM PLL demodulator block
From: |
Marcus D. Leech |
Subject: |
[Discuss-gnuradio] WBFM PLL demodulator block |
Date: |
Sat, 07 Apr 2012 19:47:20 -0400 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.24) Gecko/20111108 Fedora/3.1.16-1.fc14 Thunderbird/3.1.16 |
I was doing some experiments with this block this evening, and what I
discovered was that it requires a much better-quality signal to produce
even half-way decent audio output than my "first principles" FM
stereo decoder in my "simple_fm_rcv" application. The PLL block uses a
PLL to derive the 38KHz injection tone to re-constitute the carrier
for the DSB-SC "L-R" signal. I simply use the pilot tone itself, and
double it with a multiplier/filter.
On stronger signals, the PLL block works just fine. But on weaker ones,
my approach appears to be superior. I wonder why? Not being a real
DSP guru, I just play one on the Internet :-)
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
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