[opendtv] Re: PAL
- From: "Allen Le Roy Limberg" <allimberg@xxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 15 Dec 2006 14:14:44 -0500
As I recall GE was the chief proponent of VIRS, back before RCA was gobbled
up.
The unfortunate part of GCR signals was that the work by Charles Dietrich
and Arthur(?) Goldberg on repetitive-PN127 was not well understood by Zenith
engineers. So the frame header was not well designed for ATSC. Of course,
the breadth of the echo spectrum in the time domain was under-estimated by
everyone at the time.
Interestingly, the Chinese also seem to have been oblivious to the power of
repetitive PN sequences to generate channel impulse response using a simple
PN match filter. So, their LG coaches may well be in the dark on the
subject.
Al
----- Original Message -----
From: "John Shutt" <shuttj@xxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Friday, December 15, 2006 10:36 AM
Subject: [opendtv] Re: PAL
> I thought the NTSC cure to green people was VIRS. Gee, whatever happened
to
> all those television sets out there using VIRS? The FCC mandated that if
we
> transmit anything on line 19 of NTSC, it had to be the GCR signal. This
> displaced the voluntary VIRS that many professional Proc Amps and at least
> one consumer television set, RCA, used to automatically set chroma phase
and
> amplitude. VIRS got moved to differing lines, and most professional
> equipment using VIRS could be reprogrammed to find it, but those consumer
TV
> sets were out of luck.
>
> I guess right about the time that the technology got cheap enough to
enable
> something like VIRS, the rest of the technology got stable enough to not
> require it anymore. Not that GCR was a roaring success, either.
>
> John
>
> ----- Original Message -----
> From: "Allen Le Roy Limberg" <allimberg@xxxxxxxxxxxx>
>
>
> > Bert's view is pretty much correct. In the 70's Leopold Harwood
developed
> > circuitry that adjusted flesh tones automatically for NTSC receivers.
He
> > was working in the group developing integrated-circuit TV and FM radio
> > circuitry at RCA's Somerville, NJ facility. Jack Avins (inventor of the
> > dual-triode VTVM and a host of FM detectors) headed up the group, which
> > the
> > Japanese called the Magnificent Seven. The group was the first to put
> > whole
> > subsystems into integrated circuit chips. The count-down FM stereo
> > decoder
> > was the first IC larger than 10,000 square mils and comprised some 200
> > bipolar transistors.
>
>
>
>
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