[time-nuts] Measuring TV delays

[Brian Lloyd]

On Thu, Jan 2, 2014 at 11:10 AM, Gregory Muir <engineering at mt.net> wrote:

> Reading all of this brings back memories of a project I was involved in
> back in the early 70's in the Denver area.  NBS-Boulder was experimenting
> with injecting their time standard into the video of the analog signal
> before it hit the transmitter.


I bet they encoded it into a single line of the vertical interval. I worked
on a similar project at PBS but there it was used that to implement a
message broadcast service to send textual messages to selected affiliate
stations. It was an outgrowth of the closed-captioning system. PBS didn't
want to pay telephone charges to send the same message to all 200 stations
in the US when they already had a "pipe" into every station.

And I do remember being intrigued with the creation of the network master
clock to ensure that all the video sources were synchronized. I also
remember the early digital frame buffers that were there to deal with
different frame clock phase from non-PBS-network sources. As I recall, WWVB
was the preferred frequency reference but I also remember that they had
either a couple of Rb or Cs local references. (It was 1980 and my mind is
going. So much to remember.)

-- 
Brian Lloyd, WB6RQN/J79BPL
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