On Tue, 13 Jun 2006 10:18:17 GMT, Jan Panteltje
wrote:

+++On a sunny day (Mon, 12 Jun 2006 23:34:57 GMT) it happened Bob Dobbs EC42
wrote in pan.2006.06.12.23.34.54.717000@Quetzalcoatl:
+++
+++On Mon, 12 Jun 2006 18:34:51 +0000, Jan Panteltje wrote:
+++
+++ There is in fact no need for the 'other' sideband in DSB-SC, no problem
+++ if the receiver filters it out, that is why you can receive DSB-SC both
+++ with USB and LSB!
+++
+++Without both sidebands, it would no longer be DSB, and the reason stations
+++use DSB instead of SSB is for the use of ordinary receivers that lack a
+++BFO.
+++
+++How about providing a source of those 'undetectable" DSBSC signals that
+++one might encounter within or nearby to the CB band, instead of some
+++technobabble with irrelevant circuitry illustrations?
+++
+++OK for the last time before you enter my killfile:
+++DSB is not AM. AM is AM, and AM has both sidebands, but when we say 'DSB we mean DSB-SC.
+++idiot
+++
+++
+++
+++
**************************


We seem to be hung up on abbreviations and their applications to
analog communications.

A list of Abbreviation in analog Modulation from Introduction to
Communications System Third Edition by Ferrel G. Stremler. This is
taken from my Communications Textbook from college.


1)AM AMplitude Modulation: A CW modulation using amplitude variation
in proportion to the amplitude of the modulating signal. Usually taken
as DSB-LC for commercial broadcast transmission and DSB-SC for
multiplexed systemes.

2) CW COntinuous Wave: A carrier signal (usually sinusoidal) used for
modulation or keying.

3) DSB Double Sideband(LC or SC): a signal having two spectral
sidebands symetrically balanced with respect tothe carrier frequency.

4) LC Large Carrier: a signal in which a relatively large proprotion
of the spectrum is concentrated at the carrier frequency ( used with
DSB, SSB, and VSB).

5) SC Supressed Carrier: a signal in which a relatively small
proportion (ideally zero) of the spectrum is is concentrated at the
carier frequency ( used with DSB, SSB, VSB).

Now translating into CB lingo AM and DSB-LC are synonymous. That is
what nearly all off the shelf AM CB radios produce. Modulation takes
place in the final stage before the antenna. There are some that use
low level modulation that follow the modulated stage with further
amplification afterwards to raise the power density to a level to
effect the desired communication range with the intended antenna
system.

Please note that the difference between Large Carrier and Suppressed
carrier can be used with DSB, SSB and VSB amplitude systems. The
difference is the role the carrier itself plays in demodulaztion ONLY!
In DSB it is generally accepted that both sidebands carry the same
information during modualation. SSB is defined as a spectrum in which
only one sideband is trransmitted with or without the carrier.
Vestigial Sideband is where one full sideband is and a partial of the
other sideband is not fully transmitted. TV signals are VSB signals.

hope this helps

james