On 2007-03-30, Ivor Jones <ivor@despammed.invalid> wrote:
> "Lardboy" <lardconcepts@gmail.com> wrote in message
> news:1175290199.832255.177040@e65g2000hsc.googlegr oups.com
>> On Mar 30, 10:08 pm, "Andrew Woodvine"
>> <and...@woodvine.com> wrote:
>>
>> > The clock you used is not controlled via a signal from
>> > Rugby as you say. It's set via a signal from Anthron,
>> > Cumbria, see:
>> >
>> > http://news.bbc.co.uk/1/hi/sci/tech/6483969.stm
>
> From that article:
>
>>The national time signal is accurate to within 1,000th of a second of
>>Co-ordinated Universal Time.
>>It is controlled by two caesium atomic clocks housed at the antenna in
>>Rugby.
>
> Eh..? Atomic clocks at the antenna site..? Here's me thinking the clocks
> were at NPL in Teddington, or have I got it wrong all these years..?

The people who know what time it is run the clocks at NPL. The
caesium oscillators at the transmitter site will be used to control
the transmitter frequency and time code transitions, but the time
and frequency of the oscillators at the transmitter will be controlled
by reference to the NPL clocks (the article mentions time transfer between
the sites via GPS, which is typical). NPL finds out how its time is
doing from BIPM in Paris, which assembles a consensus view of the
time by taking measurements from national labs all over the world.

This is the usual arrangement. There is one or more caesium oscillators
at each Loran C transmitter, and in each GPS satellite, controlling the
output. Each of these is steered by reference to the collection of clocks
at a national lab somewhere, with these being steered in turn with reference
to BIPM. Owning a caesium clock isn't as big a deal as it once was. You
can buy one for your basement, if you want, for about the price of a car.

Dennis Ferguson