[opendtv] Re: Toward digital TV

  • From: "John Shutt" <shuttj@xxxxxxxxx>
  • To: "OpenDTV" <opendtv@xxxxxxxxxxxxx>
  • Date: Fri, 16 Dec 2005 10:36:17 -0500

John, talk about rehashing old arguments!  The CRC lab tested several DVB-T
receivers from several vendors, and based solely on their testing chose the
BT DVTM 2000T receiver as the only COFDM receiver to test.

As the raw data was being collected, Sinclair and others noted that the
COFDM receiver was working at certain sites when using an indoor antenna at
6 ft, but failing when using an outdoor high gain antenna at 30 ft at the
same site.

Sinclair obtained the same receivers from the CRC and retested 7 sites.
COFDM worked at 1 of the 7, while 8-VSB worked at 6 of the 7, according to
the field tests.  When Sinclair put a bandpass filter in front of the BT
receiver, it worked at all 7 sites.

Why didn't the CRC choose more than one brand of receiver for testing? 
(Even the latest 8-VSB test report by the FCC OET used several models of 
8-VSB receiver.)  Why didn't the CRC notice their own strange test results 
early on and step back to see what was wrong with their assumptions?  Why 
hasn't the CRC admitted they made a mistake, even to this day?  No checks 
and balances were built into the testing.  Every experiment needs a built in 
'sanity check' to make sure that you aren't collecting garbage data, but 
these tests ignored all the red flags.  The CRC lost credibility with me 
when they refused to even acknowledge that they did anything wrong, or that 
the Sinclair retesting showed even the possibility that they screwed up.

Go to http://www.digitaltelevision.com/cofdm/index.shtml and click on the BT
COFDM Receiver Retest link to read Sinclair's retesting results.

However, I still think that most of the blame rested with the NAB and the
MSTV for caring more about must carry than receiver performance.  I think
that they were afraid that if the receivers actually worked, they'd lose
their must carry / retrans consent status.  Why did the NAB and MSTV cancel
the Phase II testing, which would have used a real world receiver instead of
a transmitter modulation monitor, and shown real COFDM performance?


----- Original Message ----- 
From: "John Golitsis" <john@xxxxxxxxxxxxxxxxxx>

> What exactly about the CRC's "handling of the MSTV/NAB testing" has
> your knickers in a knot?  What was their role exactly, and how did
> they fail you in that role?

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