[opendtv] Re: 20060901 Free Friday Fragments (Mark's Monday Memo)
- From: "Albert Manfredi" <bert22306@xxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Sat, 02 Sep 2006 18:21:00 -0400
Al Limberg wrote:
So there's not much time left for LG to milk the 8-VSB patent.
Zenith's early receiver designs used analog demodulation, but
almost all commercial DTV receivers use digital demodulation.
Their was a TI case a few years ago in which broad product
claims were found inapplicable to later developments that were
radically different in terms of technology. A lot of the claims in
the Zenith patents use means for doing clauses, which are very
narrowly construed by presentday courts. Some of the file
histories in the Zenith patents raise questions in my mind as to
the validity of the patents.
Without knowing all the patentese mumbo jumbo, I've often wondered, and
mentioned, the same thing. Seems to me that a lot of the claims made by
Zenith on the advantages of 8-VSB for receiver design simplicitly, e.g.
against 64-QAM, proved to be baseless. The receiver designs that work even
just adequately well do not resemble the "simple" design concepts that were
supposed to make 8-VSB better.
As far as I'm concerned, the mere fact that a real-only equalizer is an
inadequate solution for 8-VSB, for the simple fact that energy in Q axis
causes amplitude in the real axis to lose focus, should be enough to put the
Zenith patent on very shaky ground. Since that was perhaps the only
significant unique concept to make 8-VSB different from 64-QAM, for the
receiver.
Other aspects of good receiver design, such alternative methods for image
cancellation, tuned front ends, and filtering the received RF signal so as
to present what looks like only lagging echo to the equalizer, were not in
the original Zenith receiver design. Estimates of what echo tolerance should
be considered adequate were way off.
I'm not saying that 8-VSB doersn't have certain advantages when it comes to
signal reception or receiver design. But I don't believe they were the ones
touted by Zenith specifically for the receiver. So as far as I'm concerned,
the courts should be very skeptical.
But the basic structure of 8-VSB, the training and sync sequences, the RS
and Viterbi schemes adoipted, the segment structure, interleaving, etc. is
being used. So I suppose that IP belongs to someone. It's just that the way
receivers ought to play with this structure to work well is not what Zenith
had described.
Bert
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