On Thursday, 12 May 2005 00:09:36 -500, "Asimov"
wrote:
RC You probably won't unless you have deconvolution math behind it.
Would you please, explain?

Hi Isaac,

The technique is one of a suite of tools derived from Fourier
analysis. The background signal contains a random response that is
largely immutable. That signal can be used as a key (if we were to
use the parlance of cryptography). The signal of interest still
appears to be just as random - in isolation. However, when both are
"mixed" (if we were to use the idiom of electronics), then the signal
of interest rises out of the noise.

It is not a simple mixing process, however, because in that idiom we
don't know the center frequency - so to speak (and instead of getting
clear speech in the typical SSB application we get something that
sounds like Donald Duck at best).

However, in Fourier analysis, you can slip the two signals past each
other (akin to matching the key of the "Gold Code" of a spread
spectrum signal to the incoming signal) in what is called cross
correlation and the deconvolved signal will spring out as a result
(when done with what is called confidence math, also found in the
Fourier repertoire). To return to the idiom of the SSB application,
the background noise becomes the center frequency.

The same application has been done to map the ocean floor using
natural wave and wildlife noise.

73's
Richard Clark, KB7QHC