[time-nuts] 90ms delay of time signal on phase-modulated carrier of BBC 198KHz transmission in the UK (was: DST change on DCF77)

[Alan Melia]

It can be justified very simply that the phase mod data on 198kHz is NOT 
intended as a standard time distribution. As far as I am aware only the 
frequency accuracy is covered in the NPL contract. Even that no longer seems 
to be monitored and offsets published.

Time distribution is on MSF 60kHz

Alan
G3NYK

----- Original Message ----- 
From: "Steve Allen" <sla at ucolick.org>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at lists.febo.com>
Sent: Wednesday, November 20, 2019 7:26 PM
Subject: Re: [time-nuts] 90ms delay of time signal on phase-modulated 
carrier of BBC 198KHz transmission in the UK (was: DST change on DCF77)


> On Wed 2019-11-20T11:35:51+0000 Peter Vince hath writ:
>> As I mentioned in a previous message about observed anomalies with the 
>> DST
>> change on DCF77, Pieter-Tjerk in the Netherlands noted that the time
>> encoded on the phase-modulated carrier of the BBC's 198KHz signal in the 
>> UK
>> was about 900 milliseconds early.  Having queried that with a contact in
>> the BBC, a problem was found and corrected, but Pieter-Tjerk reports the
>> signal is now about 90 milliseconds late.  A further query with my 
>> contact
>> reveals that this is to be expected.
>
> 90 milliseconds is a larger offset than was seen in the broadcasts that
> the BIH monitored during most of its existence as seen in these plots
> https://www.ucolick.org/~sla/leapsecs/BHsHn05p142.html
>
> This report indicates that the clock time blocks are intended to
> provide UTC
> https://downloads.bbc.co.uk/rd/pubs/reports/1984-19.pdf
>
> The current version ITU-R TF.460-6 says that time signals should
> not deviate by more than 1 ms from UTC.
>
> How can these broadcasts justify such a large offset?
>
> --
> Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
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>
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