On Sat, 20 Mar 2010, Paul Nicholson wrote:
> the calculations, but one might imagine a system comprising a
> beacon tx with slow triangular FM and a rx or coherent network
> of rxs scanning for a weak delayed echo - the same triangular
> modulation but delayed perhaps up to half a second or so.
> Software would have to de-chirp the triangle for all range
> of delays, with continuous moving average over 10 or 20 mins
> to dig the echo out of the noise.  If that could be made to
> work, researchers would be falling over themselves to get at
> your data!

By the way one can imagine some 'reverse whistler' if TX radiate
apropriate FM signal which is 'de-chirped' by dispersion in ionosphere.
Can you roughly estimate radiated power needed to observe such 'naturaly
compressed' signal? I expect it is not 'amateur' power. But it is
interesting is this power reachable for professional station or not.

Regards,
Alexander