[opendtv] Re: Why?

  • From: "Mark A. Aitken (Webmail)" <maitken@xxxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx, John Willkie <JohnWillkie@xxxxxxxxxx>
  • Date: Tue, 08 Mar 2005 07:11:58 -0500 (EST)

I submit, given your brief description of location, that your issues may have 
much more to do with lack of a receiver specification (in your case overload 
related) more than anything else. I look at the whole (hole?) lack of 
reception equation, and see a sea of problems. It's like "whack-a-mole", punch 
one down, the next one pops up. Let us (for the sake of limiting argument) 
presume equalizations issues are no longer on the table.

I have been doing a good deal of work at the private RF laboratory of Charles 
Rhodes. It is clearly the case that performance of the tuner is suspect in 
many areas where multipath is not at fault. If you have been following Mr. 
Rhodes TV Technology articles (here is just one such article...I highly 
recommend looking them all 
up...<http://www.tvtechnology.com/features/digital_tv/SignalBehavior.shtml>), 
a compelling case is being stacked up that points to internally generated IM3 
(third order intermod) and (in some cases) X-M (cross mod) as main culprits 
particularly in moderate/high input level environments.

The ATSC A/74 "Recommended Practices" document 
(<http://www.atsc.org/standards/a_74.pdf>) inadequately (in my opinion) 
addresses the requirements to reasonably assure reception. Much more needs to 
be done if we are to save OTA for ANY type/kind/standard of digital 
television...

Quoting John Willkie <JohnWillkie@xxxxxxxxxx>:

> Rather than going on whining about receiver issues (at home in TJ, my
> b2c2 card picks up San Diego DTV stations with about 15-21 SNR, but not
> the one in TJ; at my mother's house, my b2c2 picks up the TJ DTV station
> with 15 db SNR, but not the San Diego ones.  The TJ station is less than
> 3 miles from my home; most of the San Diego DTV stations are less than 5
> miles clear line of sight from mom's home.)
> So, rather than whining, I would like to know from people who were there
> (this is not a speculative issue); 
> 
> Why, when the specs were adopted, there were no (and still are no):
> 
> ATSC reference bit streams;
> ATSC receiver specifications (there are only recommendations now);
> Exemplars of bad bit streams (I have recently acquired some "off the
> air" as pertains to PSIP).
> 
> Was the issue anti-trust/restraint of trade?  Or were there more
> nefarious matters afoot?  It seems to me that the current state amounts
> to a restraint of trade just by itself.
> 
> John Willkie
>  
>  
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Regards, 

Mark A. Aitken 
Director, Advanced Technology 
*************************** 
Sinclair Broadcast Group 
10706 Beaver Dam Road 
Hunt Valley, MD 21030 
Business TEL: (410) 568-1535 
Business MOBILE: (443) 677-4425
Business FAX: (410) 568-1580
maitken@xxxxxxxxxx
 
 
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