On Sun, 25 Aug 2013, Scott Dorsey wrote:


"Single signal reception" to me would imply a narrow-sloped bandpass
filter but it sounds more like marketing than engineering.

"Single signal reception" is specific, about no audio image. Before Lamb
came up with the filter (and some argue it was someone else before him),
receivers were generally 'broad", there was no way to get rid of the
image, though I suppose at the time there were some lab receivers that
used really low IFs for some high selectivity (or that famous experiment
that used sharp low frequency antennas to prove the existence of a carrier
and two sidebands on an AM signal).

So the term applies to CW, siince at the time, the late thirties, SSB
wasn't really used by hams, and AM has no image in this context.

But in terms of SSB, it still means no audio image. So if you use a
direct conversion receiver, you get an audio image, and there's nothing at
audio that you can do to get rid of the image (same with CW and a DC
receiver, the audio filter will get rid of adjacent signals, but not the
audio image). You can't knock out the interfering signal that's on the
other side of zero-beat.

If you use a DC receiver that has phasing networks to get
rid of the audio image, you have "single signal reception" since you've
wiped out the image.

Same with a crystal filter, it allows only one sideband to pass so
anything on the other side of zero-beat is knocked down in strength
significantly.

MIchael VE2BVW