Re: DTV Reception Maps

G-squared wrote:
On Feb 16, 9:46 pm, Bob Miller <b...@xxxxxxxxxx> wrote:
Roger (K8RI) wrote:
On Sun, 15 Feb 2009 19:24:22 -0500, "N9WOS" <Do...@xxxxxx> wrote:
My version of this website said I should get 2 stations solid and not
receive any station from NYC, 50 miles to my SE.
In reality I get all but one of the stations on the list.
The calcs are not taking something into consideration.
The FCC model is going on the absolute signal strength of the primary
incident wave as it travels across the terrain. They don’t take into account
the scattered waves, and background noise.
There is two values that affect digital signals most. The relative S/N
(signal to noise) ratio. And, depending on the modulation type, the signal
level of the primary wave compared to the reflected waves.
Most receivers can receive at low enough signal levels that background noise
becomes a major factor before low absolute signal strength does. The signal
hit’s the minimum S/N radio brick wall before it hit’s the minimum absolute
signal strength wall.
If you live in a place where you have very low background noise. No buzzing
power lines. No unshielded Electrical/electronic equipment. Then you will be
able to receive more stations than someone in an electrically noisy area.
And the second factor, primary to reflected signal ratio. With 8VSB it is an
issue. When you have hilly terrain and poor line of sight signal path, then
a good portion of the signal starts becoming comprised of reflected, and
scattered waves. In some places, the reflected/scattered waves outweigh the
primary signal strength by a large margin.
However if either the primary "or reflected" is consistent and
coherent (not phasing in and out) the reception will be fine. The
problem comes from reflected signals phasing in and out with the
primary. One only has to be a few db stronger than the other with
digital and it will give good reception. OTOH if they are changing in
strength it takes time for the receiver to figure out which one to
lock onto and by then the other may be strong enough to cause a
problem.
That is 8-VSB for you, the worst modulation in the world. We share this
turkey with S. Korea, where the royalties go, Canada, which thinks it
has to do whatever we do because of the border, and Mexico, same thing.

NO other country in the world was dumb enough to go with this garbage. A
number of countries changed their minds after having first picked 8-VSB
under pressure from the US. Somewhere they found the courage to test and
then change their minds.

Bob Miller

You imply you were there during the test in Baltimore where it turned
out the COFDM receiver didn't work right. Why couldn't they find a
receiver that worked correctly? Bitching about it now is pretty much
beating a dead horse as it is very unlikely to be changed at this
point. So have a nice day.............

G²
In the first test in Baltimore done by Sinclair the COFDM receivers worked very well. That is where the controversy started. I was not there because I was in Europe meeting with numerous companies and getting detailed demonstrations of the wonders of COFDM.

The second test was fraudulent. It was allowed to be carried out by those who had special interest in 8-VSB. They COULD NOT FIND A RECEIVER THAT WORKED because they didn't want to. I offered them receivers from two different manufacturers but they refused them saying they had all they needed.

What they had was ONE so called receiver that they had to go to England on the sly to get and they proceeded to refuse the advice of the manufacturer that this "receiver", actually a transmitter monitor or test device with no front end filtering, would only work as a "receiver" with modification.

It was never meant to be a receiver and they knew it. They used it in secrecy and then puzzled over its faulty reception as if stupid. In fact it is either one or the other. They were terminally stupid or consciously deceitful.

I give them the benefit of the doubt and think they were deceitful. The test was a fraud or you have to admit that the FCC allowed terminally stupid engineers to test our modulation system with no oversight.

Again I offered them receivers from Nokia and Pace both of which were actual receivers. They refused. I offered any help they needed since I had just been to most of the COFDM DVB-T parties in Europe and knew most of the ins and outs.

They did not want my help or anyone else's because their mission was to discredit COFDM DVB-T by hook or by crook. It turned out to be by crook.

It is NOT to late to change. At any point since 1999 till now and into the future it will always be better to change than to continue with this garbage. Purely on a cost benefit basis.

Bob Miller
.

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