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From: | Chuck Swiger |
Subject: | Re: [Discuss-gnuradio] problem with audio extraction in NTSC |
Date: | Tue, 15 Feb 2005 21:37:56 -0500 |
Dear all,
I am working on extracting the audio FM signal from the NTSC
signal, and experimenting with the data file
ntsc-short-complex-baseband-8MS.dat
The idea seems simple: recenter the audio carrier to 0 frequency,
LPF and decimate and then do standard fm demod.
This is done in the attached file.
Unfortunately, although I hear something like
"winter storm will still going to stick around..."
the signal seems highly distorted as if the audio
carrier is very unstable.
I tried to fix this by tracking the video carrier,
but the problem gets worse.
One possible reason for this is that the local oscilator used to generate the IQ signal is not stable, which unfortunately cannot be fixed...
Can someone verify this problem and/or suggest any solution.
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