On Wed, 25 Apr 2007 15:29:16 +0100, Adam Sampson
wrote:

tony sayer writes:

There is a system where crystal place relays Wrotham with something like
a 384 odd kHz offset there is a BBC engineering paper on it somewhere!..

It's here -- "THE CRYSTAL PALACE FM FILLER EXPERIMENT" (great title
for a sci-fi horror film, that):
http://downloads.bbc.co.uk/rd/pubs/reports/1996-06.pdf

Ah, that was clever. The offset is 304kHz, which is 16 times the
stereo beacon frequency so the sidebands intermesh and mutual
interference is minimal. It is a little like the concept behind the
4.433MHz colour subcarrier and its relationship with the luminance
signal in TV.

I said COFDM was the best answer, didn't I? And this is exactly that,
only using analogue signals (just drop the C bit).

d

--
Pearce Consulting
http://www.pearce.uk.com