[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 12:10:03 -0700 (PDT)

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

==============================
"Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx> wrote: I have my doubts. 
However, I would ask again. if this is true:

"The devices detected DTV signals above -114 dBm-the sensitivity
threshold suggested by the technology companies of the White Space
Coalition-100 percent of the time, according to the companies."

then why don't the tuner manufacturers improve all DTT tuners to be that
sensitive? That would improve long range detection and/or allow for use
of lower power transmitters. Assuming, that is, the spectrum wasn't full
of noise makers such as these devices they want to allow.

I trust the FCC will do an objective retest.

Bert

 
       
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