🚀 go-pugleaf

"SFTV_troy" <SFTV_troy@yahoo.com> wrote in message 
news:1191108136.459409.212620@50g2000hsm.googlegroups.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