[opendtv] RV: Re: News: Microsoft, Philips Offer New White Space Test Results
- From: "johnwillkie" <johnwillkie@xxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 1 Oct 2007 13:41:52 -0700
Richard;
I've d/l the report, but I won't be able to get to it for some time.
I think WSDs are impractical, at leas unless accompanied by an integrated
spectrum analyzer and field strength meter.
WSD will probably kill people before this all over (patients in ICUs on life
support, the monitoring equipment for which uses otherwise "unusued"
spectrum.
I don't there should be a balancing test between playing online games and
interference to tv or the potential loss of life.
It ain't just sat and cable boxes that will barf when this comes about.
Once people get wsds, they will want "more power."
RG-59; cable owns all the interference received by transmitting over that.
The FCC should have mandated a phased-in approach, instead of telling cable
firms they can upgrade to RG-6 in due course, as customers request fixes.
(I think my mom's house was upgraded from RG-58, circa 1968 vintage, a few
years back.)
John Willkie
_____
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Richard Hollandsworth
Enviado el: Monday, October 01, 2007 1:13 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: News: Microsoft, Philips Offer New White Space Test
Results
You really should read the report----the three LCDs tested were susceptible
to
interference from WSD signals (not the cable connection), esp. from the
rear----
Which would be typical for a condo/apt. neighbor's WSD device:
http://hraunfoss.fcc.gov/edocs_public/attachmatch/DOC-275668A1.pdf
Also note that they used all new cable connections and didn't assess leakage
into 30-year old RG-59 with connectors in various states of disrepair....
WSD proposal for fixed devices is 36 dBm EIRP (1 watt with 6 dBi antennas).
At 2 meters, interference was noticable with WSD EIRP as low as 15.3 dBm (11
mW).
But your HDTV may be less than a foot away from your neighbor's WSD....
And LCD's probably have more "metal" in them than most TVs, RPTVs and
"sticks"....
which weren't tested.....yet....
Surely you're not suggesting all TV, DTV, Cable and SAT systems must somehow
backfit better shielding in order to accommodate WSD....
PS: Here are the channel occupancy test failures--the WSD guys want a "DO
OVER":
http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-07-3457A1.pdf
http://hraunfoss.fcc.gov/edocs_public/attachmatch/DOC-275666A2.pdf
But as I said, this all seems to be a waste of effort at this point....
holl_ands
johnwillkie <johnwillkie@xxxxxxxxxxxxx> wrote:
Yes, but cable in particular owns all the interference in their cables, and
can't create much interference outside of their cables.
Kinda sad for the vendors of the boxes, since they will have to start
replacing them. I hope they enjoyed the temporary price savings by not
having proper shielding for emerging networks in homes.
My Nextel mobile phone interferes with my computers and computers in other
people's homes; we get period 'chugging' sounds in computer speakers. The
phone has all required certifications, and the computers are class b
certified computer devices.
Then, there's the deliberate interference caused by HdRadio.
I'm afraid the commission has been ignoring the interference constraints in
the Comm Act for some time, or has redefined interference.
John Willkie
_____
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Richard Hollandsworth
Enviado el: Monday, October 01, 2007 12:10 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: News: Microsoft, Philips Offer New White Space Test
Results
WSD only needs a GO/NO-GO detector--which can be narrowband,
looking for NTSC Visual and DTV Pilot Carriers.
Sensitivity is limited by the amount of noise power in the detection
bandwidth.
DTV's 6 MHz bandwidth results in a thermal noise of about -106 dBm....so for
WSD detectors
to lower thermal noise by about 10 dB, they would need a detector with about
600 kHz bandwidth.
PS: Bear in mind that the "Listen and Detect" threshhold issue detracts from
the REAL issue:
OET tests found WSD devices cause interference to nearby Digital Cable Ready
HDTV's
(and probably also Cable STB/DVR's and many SAT Receivers for same reason)
AND THERE ARE NO WHITE SPACES ON CABLE....
holl_ands
_____
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