[time-nuts] Time transfer, internationally before GPS

Tom Van Baak tvb at LeapSecond.com
Mon Mar 3 21:09:40 EST 2014

Hi Jim,

Nice video. I had not see that old one before. Someone at NPL must be going through archives. That's very nice of them to post it. Did anyone spot the date of the filming?

My understanding is that the era of traveling clocks gradually ended as various methods of satellite time transfer began. However people still use "traveling clocks" today as a backup for GPS, or to double check GPS, or in places where GPS cannot be received, or when one needs accurate results quickly without waiting for GPS averaging or post-processing. So the practice is not dead. Most recently we all saw it used to validate the neutrino timing experiments.

Traveling clocks can also be used to demonstrate time dilation: http://leapsecond.com/great2005/

For more info on the traveling clock era make sure to read these four HPJ articles:

World-Wide Time Synchronization, 1966
http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1966-08.pdf, page 13

A New Performance of the "Flying Clock" Experiment
http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1964-07.pdf, page 1

Correlating Time from Europe to Asia with Flying Clocks
http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1965-04.pdf, page 1

'Flying Clock' Comparisons Extended to East Europe, Africa and Australia


----- Original Message ----- 
From: "Jimmy Burrell" <jimmydburr at gmail.com>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Monday, March 03, 2014 5:17 PM
Subject: [time-nuts] Time transfer, internationally before GPS

> My apologies to the list if this has been posted before but I found it fascinating. I'm guessing this was early 60's.
> I wonder if this practice continued until the advent of GPS? I be interested to know if there was an interim technology and what it was.
> http://youtu.be/SXV4c5eVkE4
> Jim...
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