Alan, I believe the subcarriers you mention are the HDRadio sideband. I've tried decoding this band but have been unable so far - it seems that iBiquity holds their proprietary standards close and I guess the community hasn't yet figured out how to decode it. If anyone is aware of an approach to decoding HDRadio, I'd love to know.
http://en.wikipedia.org/wiki/HD_Radio Ethan On Sun, Mar 17, 2013 at 10:48 AM, Alan Corey <[email protected]> wrote: > This might be a better question for the Gnuradio list, but for years I've > known that some broadcast FM stations actually transmit a second audio > program which is somehow modulating a subcarrier in the main transmission. > It probably carries mostly elevator music type junk but is rumored to be > commercial-free (a rare thing in the US!). I remember seeing dedicated > receivers advertised for this, but never actually bought one because I > wasn't sure it was active in my area. These date back to Lafayette > Electronics days I think and ever since so 40 years or more. > > I've noticed (in SdrSharp) that on some FM stations I can see what look > like they might be subcarriers on either side of the main signal. Anyone > decoded those? > > Alan > > ----- > Radio Astronomy - the ultimate DX >
