[opendtv] Re: Charles Rhodes on unlicensed devices and white spaces
- From: Richard Hollandsworth <holl_ands@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Thu, 9 Aug 2007 15:01:54 -0700 (PDT)
Auto-Detect (alone) doesn't stand a chance of working...
[Although it might be useful for WSD VS WSD deconfliction.]
Beyond about 15-20 miles from towers, it's frequently hard work
getting DTV to work with moderate/high gain antennas and preamps,
and indoor/attic locations make it even more difficult to find a "sweet spot"!!!
What's the (very negative) antenna gain on a mobile device????
The outdoor antenna fed DTV has 20-30+ dB sensitivity advantage
over WSD...which means WSD has NO CHANCE of detecting weak, but very
usable OTA DTV signals....(presuming they somehow solve the CATV EMI problem).
Mandating "more DTV shielding" isn't going to fix the
CATV EMI
problem any time within the next decade (or more)....
Too many (primary/secondary/garage/RV/luggable) TV's not yet headed to the
landfill.
I also was concerned about leakage into the CATV cabling.
Although this did not appear to be a problem in the relatively
new construction
area chosen for the FCC/OET test, it's bound to be an issue in older areas
with antique RG-59 wiring and iffy connectors (an even bigger problem).....
I don't think WSD mfrs are going to volunteer to TEST and then
PAY to have
my 30+ year old house completely rewired with dual (quad?) shield RG-6.....
and nearly every other house in the U.S.A.....
holl_ands
===================================
"Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx> wrote: Richard
Hollandsworth wrote:
> Too much attention given to auto detect of "unoccupied"
> "White Spaces". As if some "improved" sensitivity and/or
> algorithm will suddenly "fix" everything. [Why not simply
> enter zipcode to determine DTV assignments????]
That's unfortunately not fool-proof enough, IMO. The problem is that we
would be at the mercy of people who want to play with these new toys.
Meaning, they couldn't care less whether they are creating interference
with OTA TV signals.
If entering the correct zip code results in bad performance, for
whatever reason, they'll just try another zip code. And many of these
devices will very likely be portable anyway.
So the auto-detect feature is a must, I think. And a cheap device like
these need to be is not likely to have a tuner sensitive enough to work
for space communications.
> But this little hiccup obfuscates the REAL problems.
>
> DUE TO INTERFERENCE TO CABLE SYSTEMS, THERE ARE NO WHITE
> SPACES!!!!!
Which is a lucky break for broadcasters, I thought when I first saw
those unexpected results. But maybe that cable interference problem will
be a two-edged sword. If it's fixable, then a lot of the push-back will
vanish, and OTA users will get shafted.
In principle, this cable interference problem can be fixed. It's a
matter of better EMI shielding of TVs. Won't happen overnight, of
course. It would require some new FCC requirements, or recommendations,
guidelines, what have you. It would have to figure into the planning
factors.
The problem is, the tests were done with the built-in QAM tuners.
Potentially, a well-shielded cable STB connected to a monitor via
baseband cables won't exhibit these problems. So this could actually
make matters worse, giving more ammuntion to those who want to push
proprietary STBs on everyone for as long as possible, and forcing more
people to umbillical systems whether they like it or not.
Bert
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
---------------------------------
Park yourself in front of a world of choices in alternative vehicles.
Visit the Yahoo! Auto Green Center.
Other related posts:
