[opendtv] Re: 20060901 Free Friday Fragments (Mark's Monday Memo)
- From: "Allen Le Roy Limberg" <allimberg@xxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 4 Sep 2006 12:58:55 -0400
Real-only equalizers are okay as long as they have fractional spacing and a
broad enough kernel. Good to have the DTV signal made analytic before
equalization, too. Synchronous equalization as used by Zenith in the Grand
Alliance receiver is inadequate.
Allen
----- Original Message -----
From: "Albert Manfredi" <bert22306@xxxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Saturday, September 02, 2006 6:21 PM
Subject: [opendtv] Re: 20060901 Free Friday Fragments (Mark's Monday Memo)
> 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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