On Sun, 28 Sep 2003 22:25:49 -0400, starman wrote:

Soliloquy wrote:

"As the receiver's SSB reception is quite good, in difficult or crowded band conditions, we simply tune in the appropriate sideband of the desired signal and, if necessary, adjust the PBT controls."

Notice the last paragraph, using the receiver's SSB abilities to
substitute for the lack of an adequate synchronous detector. I've been
saying this for some time, though some people insist that you need
Synchronous Detection, else life isn't worth living. Since my Yaesu
FRG-100 and FT-840 don't have synchronous detection, this is what I have
done for certain difficult reception situations.

The method (discribed above) for tuning an AM signal using the SSB mode
is called 'Exalted Carrier Single Sideband' or ECSS. It works quite
well, providing the receiver has the ability to tune at 1-Khz increments
and is also very stable. This is important if you're listening to music.
The R-75 seems to fit these requirements. The advantage of a real
syncronous detector is it works independently of tuning accuracy and/or
stability, so you don't have to keep adjusting it after it's locked on
the signal.

There is another advantage. Synchronous AM detection phase locks to
the on air carrier. Without it, the phase relationship between the
carrier and sidebands is unknown, resulting is some degree of phase
distortion. Given the choice between phase distortion, and no
intelligbility at all, phase distortion wins every time. That is why
SSB doesn't sound so great, phase distortion because the relationship
between the sideband and the carrier is unknown.

There are ways with ISB to establish the phase relationship (The ISB's
are generated with carriers at quadrature)..