"SFTV_troy" wrote in message
ups.com...

Tom wrote:

...So, too, does DRM benefit from said development, making it
possible to provide a digital carrier within LW,MW and SW channeling
plans. Thast said, I find it much less fatiguing to listen to a
program on an analog AM carrier than to the same program over DRM.

I've never heard DRM. How does it sound, and why is it "fatiguing" to
hear?



DAB...because of a concerted government, broadcaster and
manufacturing industry push, the likes of which we have not seen in
other countries. A stronger parallel can be drawn to the sizable
takeup of XMRadio and Sirius satellite services in the US and Canada -
the quality stinks but the program choice and wide ranging coverage
are unique.

The quality stinks? Really? I listen to XM streams via the internet,
and they sound just fine. Is there really that huge of a difference
between Internet and Mobile Receiver?



I've been more impressed by synchronous AM demodulation of AM signals
than by a digital equivalent. It's a pity we could not get mass
manufacturing of synch AM radios and ultimately convert all AM
stations to USB with reduced carrier for power savings and reduced
interference.


What's USB? What's synchronous AM demodulation? Thanks.


Synchronous AM demodulation uses a locally regenerated carrier, fed along with the AM signal
(upper or lower set of sidebands) to a multiplier (modulator). The result is the audio. It
replaces the envelope (diode) detector usually used. You can think of it as another superhet
stage where the result, instead of another IF frequency, is the baseband audio. That's
because the local oscillator is the same frequency as the carrier of the (IF) signal, so the
difference is zero. The sidebands wind up translated to baseband audio instead of to
another IF frequency.

There are advantages. Since one set of sidebands or the other can be used, if there's a
distant station 10KHz away, causing that AM whistle, you just switch to the other set of
sidebands, whichever comes in the cleanest. Also, it doesn't depend on proper amplitude and
phase of both sets of sidebands to work properly, as does the regular envelope detector, so
it works better with impaired signals.
--
Regards from Virginia Beach,

Earl Kiosterud
www.smokeylake.com