In article ,
"David Eduardo" wrote:

"Telamon" wrote in
message

.com...
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.

The claim here "can be correctly decoded even when there is noise just
a few db below the signal itself" is no more possible than an analog
signal can be heard a few dB over the noise floor. Now both these
claims depend on the probability of the ratio of the instantaneous
noise power over the instantaneous signal modulation power.

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.

This is a rational explanation based on the argument that the total
bandwidth utilized by the digital mode may be better utilized over the
analog mode but this depends on wether an analog radio output employing
an envelope detector suffers when one side band degrades. Ask your
engineering buddies.

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.

Arbitrary numbers that do not account for individual reception
situations.

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.

OK it is fine to set limits on what is considered good or bad signal to
noise but that does not change the fact that when the signal to noise is
small both HD and analog are not easy to listen too.

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.

What do you mean by "DACed." If you mean digital to analog converter I
hope you understand that every time an analog signal goes through the
process of analog to digital conversion at the transmitter and then
digital to analog in the receiver that a set of errors and distortion is
added to the resulting analog signal but that is not the argument you
are trying to make.

Can you understand that as the signal level approaches the noise floor
that the probability of the 1/0 data stream being correctly detected
decreases? If the data stream becomes corrupted and then converted to
analog it will not represent the original programing now will it. Can
you see the similarity to analog in this regard?

--
Telamon
Ventura, California