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Old March 18th 17, 07:48 AM posted to uk.tech.digital-tv
Roderick Stewart[_3_]
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Posts: 2,074
Default TV system conversion

On Sat, 18 Mar 2017 04:50:20 +0000, Bill Wright
wrote:

At the time when when I was a baby the only way was to point a camera at
a screen. Results were unimpressive.

By 1964 things had moved on and conversion was electronic. The equipment
had 2,000 transistors and occupied two full height racks.
http://ieeexplore.ieee.org/stamp/sta...number=5266568


That was just the line-store equipment for converting between
standards with the same field rate, e.g. 405 and 625, with the output
field rate being locked to the input. The one they eventually
developed for converting between 625/50 and 525/59.94 in colour was a
monster occupying 7 or 8 racks as I recall. The delays were
implemented by modulating an RF carrier and using piezoelectric
transducers to send it as a sound wave of 30MHz (even higher than bats
can hear!) through variously sized glass blocks. It had to be kept
switched on all the time so it didn't drift oput of spec.

I have just bought a gadget that converts TVI and AHD to HDMI, VGA, and
CVBS. It handles 720p and 1080p at all frame rates. All VGA modes are
supported. CVBS is PAL or NTSC, 25 or 30fps.


This device is the size of a paperback book and cost 55. It works
perfectly. I would love to go back in time and show it to the engineers
of 1950!


I often find myself thinking the same sort of thing every time I pick
up a smartphone. I think my younger self would be impressed to see
one, not only with how clever it was to make such a thing, but how
stupid it was to make a portable gadget so fragile.

Rod.

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