[time-nuts] How did they distribute time in the old days?

Jim Harman j99harman at gmail.com
Wed Oct 14 15:55:12 EDT 2015

The Western Union clocks were still in use at broadcast stations in the
early 1970s. One problem was that the reset pulse and resulting jump in
time would come exactly on the hour, when you were trying to synchronize
with a network news broadcast that began at the network's version of 00:00.

ABC and I presume the other networks would send a tone 10 seconds before
their program started, By listening to the network on the "Cue" channel,
you would have a pretty good idea of when the news would start.

Another system in wide use around then and still somewhat today for
controlling the clocks in a large building was sold by Simplex. The
building would have a master clock (set manually by the custodian or
whoever) that pumped out tones at about 3 KHz over the power lines. These
signals would come out a couple of minutes before the hour, presumably to
avoid problems with events scheduled on the hour. The slave clocks were
designed to run a little fast, and would wait at 58:00 until they received
a tone to restart. I believe there was a special tone that would make the
clock run "fast forward," to deal with longer adjustments for power outages
and DST.

One drawback of this system is that the tones sometimes leak into audio
equipment, and in a quiet room they are often audible through the
fluorescent light ballasts.

On Wed, Oct 14, 2015 at 12:42 PM, Nick Sayer via time-nuts <
time-nuts at febo.com> wrote:

> The WU standard time service goes back further than the turn of the 20th
> century. It started in 1870.
> --

--Jim Harman

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