In article . com,
wrote:
I just don't buy the argument that nobody thought about DSB. DSB is
naturally generated from a mixer if the audio signal is zero mean.
[Again, it is best to talk about modulation schemes by discussion
modulators.] Remember, AM exists because the demod is cheaper, not
because it is any easier to generate that say DSB. AM and DSB use the
same hardware.

But there's something where a DSB local carrier has to be in phase with
the signal, otherwise there some sort of canceling effect from the two
sidebands. SSB doesn't have the problem, it just causes a pitch shift.

The only DSB I know of, (that isn't just treated as a cheap form of SSB,
where really only one sideband is used) is the L-R subcarrier in FM stereo
where they double the pilot tone to get an in phase carrier.

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)