[opendtv] Re: News: Microsoft, Philips Offer New White Space Test Results

  • From: Richard Hollandsworth <holl_ands@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Mon, 1 Oct 2007 13:12:38 -0700 (PDT)

You really should read the report----the three LCDs tested were susceptible to
 interference from WSD signals (not the cable connection), esp. from the 
 Which would be typical for a condo/apt. neighbor's WSD device:
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 
 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 
 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 
  But as I said, this all seems to be a waste of effort at this point....

johnwillkie <johnwillkie@xxxxxxxxxxxxx> wrote:        v\:* 
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  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 
  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 
 (and probably also Cable STB/DVR's and many SAT Receivers for same reason)

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