[Discuss-gnuradio] Broadcast FM is crap!

[Marcus D. Leech]

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

simple_fm_rcv.grc
Description: application/gnuradio-grc