On Sat, 08 Oct 2005 21:17:44 -0400, Dave Holford
said in rec.radio.scanner:

You can't assume that any filter over 3kHz or so is symetrical about the
'carrier' frequency just because that is the normal configuation of consumer
equipment.

You can't assume that any given SSB signal will fit in a 3 KHz
bandwidth, just because all current signals do.

But I can assume that all filters currently in production are
symmetrical about the center frequency within 10% - because they all
are.

Just for fun I am currently listening to an LSB conversation on 3763 kHz with
a 7.5 kHz filter and I cannot hear any sign of the conversation on 3765 - but,
the noise is a bit higher due to the wider filter. I wouldn't normally do this
but just had to try it. Of course, if I select DSB or ISB I get both signals,
although the 3765 conversation is inverted and shifted in frequency.

With what receiver and which filter? What kind of detector? I can
design any number of receivers that will do what you claim, but that
doesn't negate the fact that the standard filtered superhet SSB
receiver will receive a signal on the "wrong" sideband if the filter
is wide enough and the detector is set correctly.

I don't know how much DSB is still on the air but a quick google search for
"double side band' gets over 12 million hits. It may not be encountered in
normal voice communications on HF and scanner frequencies but it is hiding in
other places and frequencies from a quick look at some of the hits.

I said DSBSC, not DSB. There's loads of DSB on the air today, it's
just not DSBSC.