[time-nuts] What time is it anyway?

[Steve Rooke]

Magnus,

Excellent links, as always, many thanks. Much to digest. Clock
comparison looks an interesting area.

Steve

On 30 March 2010 13:12, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:
> Steve Rooke wrote:
>>
>> So there are 250 clocks, presumably, spread around the World and owned
>> by the member countries of the BIPM.
>
> There is a fair spread geographically, yes. See map:
>
> http://www.bipm.org/en/scientific/tai/tai.html
>>
>> Their time is somehow compared centrally and an "absolute" time is
>> determined from them.
>
> They are compared by various methods in a network style of operation. The
> sites are compared against each other and the clocks of each site is
> compared against the clock driving the network comparison. Hence, through
> these steps phase differences can be cranked out.
>
> http://www.bipm.org/en/scientific/tai/clock_comparisons.html
>
> Equipment calibrations:
> http://www.bipm.org/jsp/en/TimeCalibrations.jsp
>>
>> Each clock will then have a delta to apply to it's own time to provide the
>> BIPM
>> "absolute" time which then allows each member country to use its own
>> clock for timing.
>>
>
> Yes, out comes the delta of each individual clock as well as the individual
> labs. These are reported upon regularly to be found in BIPM circular T:
>
> http://www.bipm.org/jsp/en/kcdb_data.jsp
> ftp://ftp2.bipm.org/pub/tai/publication/cirt.266
>
> Useful resource:
> http://www.bipm.org/jsp/en/TimeFtp.jsp?TypePub=publication
>>
>> This sounds like a logistic and bureaucratic nightmare,  I will have
>> to look further as to how this is achieved. Any pointers gratefully
>> accepted.
>
> I hope the above pointers get you started.
>
> They have spent some time cooking this up, yes.
>
> Toss into that, we have not really spoken too much about how they process
> things. I can't tell you too much about it, except that I know that their
> tool is called ALGOS. If someone could give me the appropriate articles I
> would be greatful.
>
> Cheers,
> Magnus
>
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-- 
Steve Rooke - ZL3TUV & G8KVD
A man with one clock knows what time it is;
A man with two clocks is never quite sure.