Topband: phase

[Jim Jarvis]

How do you distinguish between a 180 degree phase shift,
and polarity reversal?  Unless you're timing logic edges,
or counting cycles, they look the same to me.  

I was designing a log-periodic stack a few years ago, and
looking for a good way to do ping-pong... in/out of phase
on the pair, which was frequency independent.   

The easy way turned out to be reversing the feedline at the
boom of one of the lpda's.  It was done using a relay, fed
via 12v phantomed up the feedline.  

The Topband discussion had to do with feeding each ear with separate
signal sources...or the same source, phased by 180 degrees.
True diversity reception (separate rx's, separate ant's) will 
give you some immunity from fades.  I don't think it does much for
minimum detectable signal.
 
With respect to multiple rx's or phased audio, with a single antenna
source, I suspect all it does is warp your brain a bit, with no
net improvement in copy.  

Where split headphones make a lot of sense is with split operation.
You can listen to the dx in your left ear, and the pileup in your
right.  Or, your run freq in the left, and pounce stn in your right,
if you contest.  Spatial separation of the sources helps the brain 
keep them apart.  (The MP does this with its 'dual receive' fn.  The
PRO doesn't...it mixes the two signals in one audio path.)

73, N2EA
jimjarvis at ieee.org