[4candles]

It's well known that FM broadcasts have a spike at 19KHz (the "pilot tone"), and are also subject to a frequency roll-off at around 15KHz.

Stereo FM signals are modulated with one part of the signel (L+R) transmitted in the 0-15KHz range, and the other part (L-R) transmitted in the 23KHz-53KHz range - as shown by this diagram:

http://hyperphysics.phy-astr.gsu.edu.../radio.html#c2

But back to the subject - how do you think the radio signals travel from the original broadcaster to the cable company's distribution center? Even if the cable company is rebroadcasting from a local analogue FM transmitter, how does the signal travel to that FM transmitter?

The answers to these questions are generally unknown, but I have read that France uses MP2 compression via satellite, and the UK (specifically, the BBC) uses NICAM digital signals. Someone has mentioned that the BBC have now switched to MP2 distribution for their FM transmitters, but I haven't found any secondary sources to back that up - the fact that they use (used?) NICAM in the past is well documented.

So whilst we don't know for sure how the Cable company got the radio signal, an MP2 feed is a common method, and the spectral analysis seems to confirm that. The radio station in question (FM4) broadcasts via digital satellite in Europe (at 192kbps), which would seem a likely source for the cable company to tap into.

And we still don't know how the satellite transmission is fed....

Dave.

EDIT: If anyone wants to compare the sound of this torrent with the digital satellite version, the original 192kbps MP2 data is torrented here:

http://www.dimeadozen.org/torrents-d...id=42814&hit=1

As I write this, there are four seeders, and no leechers, so a good time to hop on - and it's only 77MB (being the original MP2 data).