[opendtv] Re: Patent application on 8-VSB equalizer
- From: "Allen Le Roy Limberg" <allimberg@xxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 7 Jul 2006 17:36:32 -0400
Doug is correct, that a lot of segments have to be accumulated so DSS
sequences gain in strength over ordinary data. The channel impulse response
(CIR) is then derived by measuring the peaks of the correlation response.
This accumulation is done anyway in receivers that use DSS sequence
discrimination to decide on symbol phase.
These techniques work on received symbols before any equalization. The
determination of initial equalization coefficients from PN sequences in the
DFS by correlation works on received symbols before any equalization. These
techniques can be used on envelope of IF DTV signal (presuming presence of
pilot) so demodulation by synchronous detection is not even necessary.
I don't know if anyone is using this technique in product. Until recently
most designs have used blind equalization backed up by training on known DFS
signal by Wiener method, rather than initialization from computed channel
impuse response.
More recent designs lock symbol phase to pilot carrier. Broadcom does this,
I believe.
Al Limberg
----- Original Message -----
From: "John Shutt" <shuttj@xxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Friday, July 07, 2006 9:00 AM
Subject: [opendtv] Re: Patent application on 8-VSB equalizer
> Al,
>
> Since the patent was issued six years ago, can I assume that no product
has
> been made thus far using this technique? Is the theory much easier than
the
> practice?
>
> I've always wondered how you can use the data segment sync bits to
estimate
> multipath when you first have to demod the 8-VSB before you can read the
> data segment sync bits, which means you have to equalize out multipath,
> which means you need to estimate the multipath. All very chicken and egg
to
> me.
>
> John
>
> ----- Original Message -----
> From: "Allen Le Roy Limberg" <allimberg@xxxxxxxxxxxx>
>
>
>
> > 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.
> >
> > Al Limberg
>
>
>
>
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