> It would be useful to use some black box where you use your Tx antenna
> as an alternative to the directional beverages even to the point where
> you could add them and use the omni directional in the background
> along with your beverages. Alternately run a second receiver and mix
> the audio with stereo headphones so that you are not just listening in
> one direction but checking other azimuths at the same time in the
> other ear !!
Mixing in a signal from a different direction at audio is exactly like
mixing it at RF! It decreases directivity and decreases S/N ratio of
the system.
I can record in stereo WAV files with phase-locked receivers, and
demonstrate that if someone has a web page. What you I find is
this:
1.) If the signals are in phase and have nearly-equal S/N ratios and
mixed to mono from widely separated antennas, I get substantial
S/N improvement in the sum. But it is impossible to hold the signal
in-phase for long and QSB makes the levels vary rapidly also.
2.) If I listen in stereo I get slightly less enhancement but QSB,
phase and levels have less effect so the enhancement is more
reliable.
3.) If I listen in two different directions, either in stereo or mono, it
decreases S/N ratio a quite noticable amount. The change is about
the same as just using a poorer receiving antenna.
73, Tom
(W8JI@akorn.net)
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