[opendtv] Re: 7" ATSC TV
- From: Frank Eory <frank.eory@xxxxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Thu, 19 Apr 2007 11:42:12 -0700
Dale Kelly wrote:
Please see the recent FCC test results of eight current model "5th Gen" type
receivers. None met the minimal A/74 recommendations: two were close while
the others were poor. However, none performed nearly well enough for the
packed spectrum environments existing in most metropolitan areas. They are
be particularly vulnerable to interference from the new unlicensed services
which will operate in "white spaces" between existing DTV channels.
Given that this performance short coming is related to poor RF front end
design I know that you won't be surprised at the findings since you have
recognized and discussed this potential problem in the past.
It seems to me that to undo all of the excellent and costly work done to
improve VSB processors by using a cheap front end, is unconscionable. There
are a number of off-the-shelf tuner designs which would prevent such
problems if used and the additional cost would be small when manufactured in
mass.
I agree that not meeting the minimal A/74 recommendations is pretty
lame, but I don't know how you can say with certainty that these
performance issues are entirely related to "poor RF front end design." A
top-notch tuner coupled to a mediocre baseband chip or a mediocre tuner
coupled to a top-notch baseband chip could both exhibit similar
performance shortcomings in end-to-end tests. Even issues that appear to
be primarily RF front-end-related (like adjacent channel rejection) may
be significantly affected by baseband chip parameters like ADC
performance and resolution, front-end digital filtering (or lack
thereof) and other elements of the baseband chip design.
In any case, the market will continue to decide how much incremental
receiver performance is worth. My guess is that CE products will
continue to include the very best RF front end + baseband chips, as long
as those also happen to be the cheapest ones -- because the perceived
value of an ATSC receiver to most consumers is pretty close to $0.
If a "decent" tuner can be had for around $2 and a "decent" ATSC
baseband chip can be had for around $5 (hypothetical prices, but
probably not too far out), why would any TV manufacturer pay more than
that for higher performance components? Can he charge more for the TV
set if he does? Highly unlikely.
-- Frank
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