Timing information from MSF ("Rugby") etc.

[MarkMLl]

Can anybody provide chapter and verse on whether the timing information provided by the UK NPL on MSF is considered to be a secondary, tertiary (... and so on) or /what/ standard?

They provide useful information at e.g. https://www.npl.co.uk/products-services/time-frequency/msf-radio-time-signal/msf_time_date_code which includes

[quote
The carrier frequency is maintained at 60 kHz to within 2 parts in 10^12.
...
The timing of these edges is governed by the seconds and minutes of Coordinated Universal Time (UTC), which is always within 0.9
seconds of Universal Time (UT1),
...
this second marker is transmitted with an accuracy better than +-1 ms.
[/quote]

but I've never been able to determine where these figures fit in their overall calibration hierarchy.

MarkMLl

[jpb]

The NPL guide might tell you - I don't know because I didn't want to enter all my info to download it:

https://www.npl.co.uk/products-services/time-frequency/npltime/product

I think from what you put that MSF is based on primary sources but there is a lot of uncertainty in making use of it with the second markers only being within +-1ms and though the frequency is maintained at 2 parts in 10^12 the various receivers (I have an quartzlock one) are only accurate to something like 10^-9 I think or worse so the question as to what the source is, is an academic rather than practical one.

I'm not sure why you're asking the question.

[MarkMLl]

Thanks for the link, I'll follow it up (something I might have done already, but I'll check) and report back.

Updating: that PDF covers a time standard delivered by fibre. It does however state explicitly that

"Several countries operate radio signals providing access to a
UTC(k) time scale. Both accuracy and traceability are below MiFID II
requirements apart from voice trading."

which implies that MSF is better than one second but says nothing more definite.

The "MSF signal technical data" link goes to the same document from which I quoted earlier.

I don't think that there's much point in my having another attempt to ask them directly... I tried early this year without response and the COVID-related lockdown is unlikely to have made them more communicative.

The bottom line for the moment at least appears to be that the leading edges are reliable to +-1mSec i.e. roughly 3ppm, but it's not at present possible to ascertain whether the NPL- as the UK's statutory standard- is prepared to call this secondary, tertiary etc.

MarkMLl