[time-nuts] Ronald Held's main question

[Neon John]

On Tue, 18 Dec 2007 00:05:29 -0800, Hal Murray <hmurray at megapathdsl.net> wrote:

>It was probably in the late 70s that a friend showed me a small booklet from 
>NBS.
>
>It was describing how to use TV signals to calibrate your local clock.  I 
>think NBC and HP cooperated.
>
>I think the story was that NBC had their whole network of TV stations locked 
>to a master clock.  It was very stable except for jumps when the phone 
>company rewired some link.  I think they used to measure various sites 
>monthly and publish the differences between local tick and correct time.
>
>Does anybody remember that one?

yep, but the fly in the ointment was that even though the network color burst
frequency was very accurate, the signal that got broadcast frequently wasn't.
Ch11/atlanta where I used to moonlight some is an example.  The first thing that
happened to the network signal when it hit the facility was that it got digitized in
a frame store.  This allowed the network feed to be genlocked to the house clock
which was an ordinary quartz oscillator.  There went the NBS accuracy.

This frame store, which buffered two frames, consisted of a floor to ceiling 19" rack
packed as tightly as possible with card containing either 8 or 16K RAM chips
(memory's fuzzy on the size).  That frame store was still in use in the mid 90s.

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Daddy, why doesn't this magnet pick up this floppy?