Re: [Discuss-gnuradio] Broadcast FM is crap!

[Andrew Davis]

The is a lot of really cool reasons for the stereo to be the way it
is, check out http://transmitters.tripod.com/stereo.htm  it's an
amazing read.

Also the problem of no stereo signal is probably with modern music,
there is not much difference between L and R anymore, just a single
channel of mass produced noise, so since the're subtractive, silence
is broadcast on the L-R signal, not like days past when Pink Floyd
would fly you though space on both channels!

On Sun, Feb 19, 2012 at 11:50 AM, Marcus D. Leech <address@hidden> wrote:
> Spent some time yesterday evening building up a stereo FM receiver in GRC.
>  I know there are already a few of these for broadcast FM,
>  but for personal education reasons, I thought I'd build something up.
>
> Attached is my result.
>
> It seems to work reasonably well (better than the existing example WFM
> stereo receiver on the same signals).
>
> But something I've discovered is that about 30% of the program material
> coming out of my fave radio station doesn't even have
>  any L-R signal present.  I mean, I can understand during announcements,
> commercials, etc.   But a lot of the musical material
>  doesn't have any L-R, even modern material.
>
> But I never really knew the gory details of FM Multiplex before--didn't know
> the L-R channel was DSB-SC, for example.  Never had cause
>  to think deeply about it.  I knew there was a 19kHz pilot tone, and that it
> was doubled to 38kHz (usually with a PLL), but I always thought
>  it was used as a switching signal of some sort.
>
> If I get keen, I'll extend this to include RDS decoding.
>
> --
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
>
>
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