"Sal M. Onella" wrote in message
...
"Cecil Moore" wrote in message
...
Sal M. Onella wrote:
By the old TASO standards, you need over 40 dB s/n to get a nice
picture,
which requires a lot more peak RF power. By comparison, the digital
signal
needs only about 17 dB s/n.
What happens at a 12 dB s/n for both? That's probably
what happened here during Hurricane Ike.
--
73, Cecil http://www.w5dxp.com
Digital: No lock and no indication of trying to lock (which is provided
on
some receivers)
Analog: Recognizable signal, possibly with sound, probably with no color
and so much snow as to be unwatchable.
For the analog experiance, I am relying on bench tests I did with a TV
servicing generator. For baseline, I advanced the RF amplitude just to
the
point where I had a snow-free picture. Next, I added 10 dB attenuators and
noted the results with each addition.
One: observable snow, no big deal
Two: Objectionable snow, this ain't good
Three: horrible snow, I can't watch this.
Four: Is there even a picture?
This is my experience too. 36 db S/N gives you a decent picture, 55-60db
S/N gives you a good fade margin for analog and a perfect picture (if
convergence and purity are capable)
For digital, 30 db S/N gives you a "perfect" picture if it is 1080i, or no
better and maybe worse if it is only 480i but you still need at least 50 db
S/N for fade margin or everything will break up when there is a 5-20 db
fade. At least with the Analog signal, you will still have audio during
deep fades.
Smith makes sense in light of consumers who only complain about what they
see. Most people won't be doing TV DXing. Tough luck for those who do.
There is a real big point about all the extra connectors as the
entertainment system grows. Lots of people needed to have someone hook it
up for them, and now complain about having to punch too many buttons on too
many remotes to get their picture and sound.
As a ham, I like to be able to do things the kids and consumers might not
want to be bothered with. If only ARRL would consider this concept. Ham
radio will never be a mainstream consumer product unless it ceases to be ham
radio completely.