[Discuss-gnuradio] Automatic Fine Tuning for FM demod

[Marcus D. Leech]

I've just updated simple_fm_rcv to implement a simple Automatic Fine 
Tuning function.

This function measures DC offset on the output of the demodulator block, 
and uses that to drive a parameter of the freq-xlating
  filter block that's on the input.  It seems to work OK in my simple 
tests this evening.  This is a piece that typically wouldn't be required
  if using UHD hardware, but the RTL-SDR radios have, ahem, 
less-than-ideal master oscillators, so I wanted to see if AFT would be
  possible.

So, in effect, I've implemented a feedback loop within the flow-graph.  
But it's via a polled value, so it doesn't violate the rules.

--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org