[SystemSafety] Data across the UK National Grid

[paul_e.bennett at topmail.co.uk]

On 11/10/2016 at 12:12 PM, "John J SPRIGGS" <John.SPRIGGS at nats.co.uk> wrote:
>
>Actually 1500m, it used to be a frequency reference at 200kHz 
>derived from an atomic clock, but they changed it to 198kHz - I do 
>not know if it is still a frequency reference at this new 
>frequency.
>
>John
>Showing my age by saying new - it was about thirty years ago...

I think there are several on this list who will remember the change.

I remember there was quite a conversation in Wireless World and
Practical Electronics at the time the change happened. Most of the
talk worked towards how to adapt to the change and maintain the 
time reference functions. The carrier frequency setting remained 
accurate despite the frequency change and many systems released 
since the date were configured to use the new frequency standard.

Of course, if a time of day reference was needed, decoding the 
signal (60kHz) from Rugby was the alternative. Using the carrier
frequency standard and the Rugby clock would get you a consistently
accurate time reference.

Nowadays, many use the GPS time reference.

Regards

Paul E. Bennett IEng MIET
Systems Engineer

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