In article . com,
wrote:

Tom wrote:
wrote:
Michael Black wrote:

I glanced at it and maybe missed something, but DSB is AM. And
he certainly says it at the outset, and when he's talking about
the components he's talking about 2 sidebands and a carrier.

Now, "DSB" often has fallen into the meaning of "DSB with no
carrier", but technically one should specifically define that
there is no carrier.
Snip

Back in 1972 when I took my FFC 2nd and 1st class exams DSB was
defined as the sidebands with a supressed carrier. A signal with
both sidebands and the carrier was simply AM with a BW disgnator.
.Now that diffintion may have slipped over the years, but from my
perspective AM means both sidebands, with a carier DSB means both
sidebands without the carrier, and ISB means two different
sidebands with no carrier. I only have received the later, ISB, a
very few times mainly on ancient STL links.

It might be useful to check out what the ITU says these days
about "AM", both sidebands with carrier", and for this
conversation, "DSB" being both sidebands without the carrier.


That high authority, Wikipedia, at http://en.wikipedia.org/wiki/DSB
says, "in telecommunications, double-sideband transmission - see
also double-sideband suppressed-carrier transmission (DSB-SC) and
double-sideband reduced carrier transmission (DSB-RC)".

That is supported by ATIS Telecom Glossary 2000 (ANSI approved) at
http://www.atis.org/tg2k/ : "DSB: Abbreviation for double sideband.
See double-sideband transmission." --- "double-sideband (DSB)
transmission: AM transmission in which both sidebands and the
carrier are transmitted." and "DSB-SC: Abbreviation for
double-sideband suppressed carrier. See double-sideband
suppressed-carrier transmission." --- "double-sideband
suppressed-carrier (DSB-SC) transmission: Transmission in which (a)
frequencies produced by amplitude modulation are symmetrically
spaced above and below the carrier frequency and (b) the carrier
level is reduced to the lowest practical level, ideally completely
suppressed. Note: DSB-SC transmission is a special case of
double-sideband reduced carrier transmission."

Accordingly, DSB=AM unmodified and AM is the essential first step
for its modified variants SSB, ISB, DSB-SC/DSB-RC.


I guess that diffintions aren't static, er fixed. Thanks for the
clarification.

Looks to me that acronym DSB does not define the carrier condition.
That's why the dash and more letters.

--
Telamon
Ventura, California