[opendtv] Re: Patent application on 8-VSB equalizer
- From: "Allen Le Roy Limberg" <allimberg@xxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 7 Jul 2006 20:21:22 -0400
The DTV industry found out pre-echoes of strength could be much longer than
4 microsec. -- Maybe up to 30 microsec. Then there is the repeat problem
with FIR filtering. Also, channel repeaters can make bad pre-echoes in the
transition region.
Too bad legacy receivers kept us from going to triple-PN1023 field sync,
which handles 90 microsec.echo range easy as duck soup.
Al
----- Original Message -----
From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Friday, July 07, 2006 6:14 PM
Subject: [opendtv] Re: Patent application on 8-VSB equalizer
> Al Limberg wrote:
>
> > U.S. patent No. 6,081,301, titled "DTV CIRCUITRY FOR
> > MEASURING MULTIPATH DISTORTION BASED ON GHOSTING OF
> > DATA SEGMENT SYNCHRONIZING SIGNALS", issued to me 27
> > June 2000 and is assigned to Samsung Electronics.
>
> Well, sonuvagun, it says close to the same thing as that later patent
> application.
>
> One thing you explain in there is how the middle PN63 sequence can be
> used to detect pre-echoes to -53.7 usec. But then you minimize the
> importance of this, based on measurements which, at the time, indicated
> that anything more than -4 usec was going to be rare.
>
> If matched filters in the new tuner designs don't take care of much
> greater pre-ghost than 4 usec, it would seem to me that using this
> middle PN63 technique in equalizers would be ideal for fairly widely
> spaced unsynchronized on-channel repeaters. Because in this case,
> there's no issue with dynamic multipath. The pre-ghosts are steady as
> can be.
>
> Bert
>
>
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