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Old March 8th 07, 04:50 AM posted to rec.radio.shortwave
David Eduardo David Eduardo is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 726
Default Decision Has NO IMPACTon HD/Internet/XM/Sirius News and Talk Stations


"Telamon" wrote in message
...
In article ,
"David Eduardo" wrote:

"Telamon" wrote in message
news:telamon_spamshield-
I don't need to get an HD radio and drive around LA. This is just plain
physics. Information transmitted is determined by the amount of power
and bandwidth applied to a signal. You can not have a more reliable
transmittal of a signal on less power and bandwidth. Do you get the
picture?


No, because the limiting factor on analog is, in most cases, noise. The
digital system itself has better system specs, and the reception systems
can
make use of a much weaker digital signal than they can an analog one.


You can say no all you want. What I stated is the basic principles of
information transmission. Go look it up. Too bad if you don't like it.


I had an interesting discussion with our engineering department in LA this
morning...

The general consensus as to why far less signal is about as effective has to
do with noise. A digital signal can be correctly decoded even when there is
noise just a few db below the signal itself. HD duplicates the same data on
both sides of the carrier, so there is the ability to select the best data,
much like diversity reception. And HD "dithers" in the case of small
dropouts.

Analog requires something over a -57 db noise floor to be useful to the
average listener, and something in the -60's for really nice FM reception.

All the engineers (and there are 8 of them for our 5 signals) believed, in
conclusion, that the determining factor on usability on an analog signal is
also noise, which is why in LA we get no listeing outside the 64 dbu on FM
and about the 10 to 12 mv/m daytime and the 15 mv/m night on AM.


Noise lowers the dynamic range available for digital and analog
transmissions. Too bad if you don't want to hear that either because
that is the way the ball bounces. People that do not know what they are
talking about may think otherwise but that does not change reality for
them or the rest of us.


The reality is that the HD data can be extracted and DACed when the noise is
only a few db below the signal itself.