"Phil Kane" wrote in message
...
On Fri, 14 Dec 2007 06:43:35 EST, Bill Horne
wrote:

BTW, given a choice between LSB and USB, the military's
preference is
for Upper sideband, since using USB makes it easy to talk
another
station on to a net frequency: if his voice sounds high,
then so is his
frequency.

USB was the commercial standard for the 50 years or so
that I've been
in that business. Even with ISB (Independent SideBand)
where each
sideband has different information, the "lower"
sideband(s) are not
inverted relative to the "upper" sideband(s).
--

73 de K2ASP - Phil Kane

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon

e-mail: k2asp [at] arrl [dot] net

I'm not quite sure what you mean by "inverted". ISB
sidebands have the same orientation as normal sidbands,
meaning the lower is inverted with regard to the upper
sideband and in regard to the freqencies in the original
signal, i.e., the higher frequencies in a voice are lower in
RF absolute frequency although a greater separation from the
"carrier".
Single sidband transmission goes back to its early use
for intercontental radio links such as the telephone service
from the U.S. to England provided by AT&T. I've forgotten
the dates but think it was the late 1920's. The equipment
was enormously complex compared to later ham SSB stuff. One
of the methods used for privacy was sideband inversion
applied to both sidebands, that is, the lower voice
frequencies were further from the "carrier". If one had a
reasonably selective receiver the signals could be heard
clearly. This method was used mostly by RCA. ATT used a much
more complex system which split the voice base band into
several smaller bands and "shuffled" them with or without
inversion. One could tell it was voice but not decipher it.


--
---
Richard Knoppow
Los Angeles, CA, USA