archive: SETI Theoretical question

SETI Theoretical question
Sat, 19 Sep 1998 14:43:14 +0600

For some time I've been studying S/N improvement, and have been
frustrated by the inability to use lock in methods :-( If only we could
reach out and modulate the signal and not the noise! I have reached
the limit on bin size due to L.O. stability (see Shuch, H.P., "Compact
and Clean L-Band Local Oscillators," in _Ham Radio_, Dec. 1979, p. 40).
I have no confidence in this idea, but what the heck.
The suggestion of a background reference dipole lead me to the conclusion
that only two identical antenna/receivers would be practical. Then I started
experimenting with nutation, and here we are. Paul's thought that there
is probably not a use for this has me doubtful about the idea...
Of course I keep accidentally creating the Dicke switch!
The logic here would be to offset the feed to a "reference" position.
The "signal" (center position) could then clock the multichannel scaler up,
and the "reference" clock down.

G.D. Renkes, L.R. Thorne and W.D. Gwinn, "Digital modulator and synchronous
demodulator system: an alternative to the analog phase detector"
Rev. Sci. Instrum. 49(7), 994 (1978)

S.Cova and A.Longoni, "Versitile digital lock-in detection technique:
to spectrofluorometry and other fields"
Rev. Sci. Instrum. 50(3), 296 (1979)

Skou, Niels. _Microwave Radiometer Systems: Design and Analysis_
(Norwood, MA: Artech House, 1989)

John Willcox
Project Argus Observatory FM29fx