"Kristoff Bonne" wrote in message
...
c. Analog has sync detection, which eliminates most of the fading most of
the time. This is much better than drop outs.


AFAIK, sync detection is against partial-cochannel interference, not
against fading.

Perhaps its greatest benefit is improved immunity from distortion due to
selective fading, especially that which sucks out the carrier. Suppressing
one sideband also reduces fading distortion. The Dream software DRM decoder
also incorporates a synchronous AM, selectable sideband detector. The
improvement in listenability for a DSB AM signal in the presence of
selective fading is truly remarkable when it is used in synchronous ECSS
mode.

Broadcasters would free spectrum, reduce interference, be more energy
efficient, maintain compatability with the huge installed base of AM radios
by converting to SSBc mode. Radios manufactured with DSP capable of
synchronous AM selectable sideband would probably require less silicon than
DRM (read cheaper), be more energy efficient (read eat batteries more
slowly), be compatable with the huge installed base of DSBAM transmitters
and the then-growing number of SSBc transmitters. Why don't we hear more
about this alternative from broadcasters and manufacturers? Have I missed
something?

b. An analog radio with sync detection would sound better than a DRM
radio using the same radio spectrum bandwidth.

Do you actually have a DRM-radio? Can you compair?

While DRM might give the subjective impression of wider frequency response
and higher signal-to-noise ratio, to fit within a 10 or 20 kHz bandwidth, it
necessarily uses a very low bitrate lossy codec. I find that listening to
such codecs is aggravating, moreso than (and very different from) the
dynamic changes in spectral balance from an AM transmission in moderate
fades.

Moreover, the DRM spectrum is rectangular - even energy distribution. If we
take our 10 kHz channel and use SSBc to fill it (carrier at channel edge),
we will get nearly 10 kHz audio bandwidth. If we also use pre-emphasis (as
is done in FM), or one of the (ancient) Dolby or dBx type noise reduction
systems to lift the treble energy in the sideband, we will get a much
improved S/N. Still very listenable on a conventional DSBAM radio with
typical IF and AF passbands.

Why don't we hear about this approach? It sounds so easy I think I should
build a transmitter and experiment with it! There must be a catch...

Tom