[opendtv] Re: Delay
- From: "Donald Mccroskey" <mccroskey2@xxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sat, 16 Dec 2006 00:34:27 -0800
The AT&T microwave system which reached the west coast in the summer of 1951
was not the problem. It was RF all the way, demodulated to video only to
feed the network stations. The local video loops to/from the network master
controls in New York, Chicago, Washington, D. C., and Los Angeles were of
variable quality and detectable to noticeable ringing and smearing were
always present to some degree. The worst situations were news broadcast
which originated in New York, in and out of Washington, D. C., back to New
York, in and out of Chicago, in and out of Los Angeles to west coast
affiliates. That would be 9 local video loops in cascade. A sports or
special events program would add at least 2 more paths. I was the ABC west
coast transmission engineer from 1957 to 1960 and dealt with network
transmission problems reported by the Pacific coast stations. The passive
equalizers at the TV stations were adjusted to give near flat frequency
response to 4 MHz with a sharp cut-off. Ringing was the inevitable result.
Occasionally I would talk the Telco craftsman to equalize to give a more
gentle roll-off. 2 dB down at 4 MHz with reduced ringing was a good
trade-off to me. But multiplying this times 9 (as in the above example
could not be allowed. Add kinescope recording and playback through
iconoscope film cameras to this chain, and you really had problems.
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] On
Behalf Of Dale Kelly
Sent: Thursday, December 14, 2006 12:50 PM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: Delay
Mark S. wrote:
Television Digest reported decades ago (in the black-&-white days) about
> an American television delegation that went to the UK in its 405-line,
> 3-MHz-video-bandwidth days and found the pictures superior to those in
> the U.S. There was much discussion about why.
I lived in England for a number of years during the 1950s and remember the
early 405 system well. Other than being able to count the scan lines from
across the room the image quality was good. I tend to agree with Al Limberg
regarding the careful production but also suggest that the excellent plant
and distribution engineering, under control of the BBC, resulted in
consistent high quality throughout the network.
That was not the case in the U.S. where the networks generally delivered a
very good product to the AT&T distribution system in New York. However,
after distribution for thousands of miles through hundreds (thousands?) of
amplifiers, the quality deteriorated significantly. Then add the many
independently owned Network affiliated transmission and microwave systems
around the country, often not maintained to network standards, and the end
result was often marginal at best.
Dale
> -----Original Message-----
> From: opendtv-bounce@xxxxxxxxxxxxx
> [mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Mark Schubin
> Sent: Thursday, December 14, 2006 10:44 AM
> To: opendtv@xxxxxxxxxxxxx
> Subject: [opendtv] Re: Delay
>
>
>
> > Our eyes clearly do not deceive us; when visiting Europe we do see an
> > obviously superior analog television picture. However, PAL is
> not the source
> > of this superiority.
> Agreed.
>
> > The source of this superior "PAL" picture is actually the additional 25%
> > bandwidth allocated to that signal and an additional 100
> vertical scan lines
> > used per frame.
> Perhaps. Perhaps not.
>
> Television Digest reported decades ago (in the black-&-white days) about
> an American television delegation that went to the UK in its 405-line,
> 3-MHz-video-bandwidth days and found the pictures superior to those in
> the U.S. There was much discussion about why.
>
> TTFN,
> Mark
>
>
>
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