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" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
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 <[email protected]> WGS-84 (GPS)
UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat
+36.99855
1156 High Street Voice: +1 831 459 3046
Lng -122.06015
Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m
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