[time-nuts] DST change on DCF77

[Peter Vince]

At the end of October, after the DST change, a colleague had noticed an
error on his DCF77 decoder program, and wondered if there had been a
transmission error - it is always hard to believe your own code is at fault
:-)  Pieter-Tjerk de Boer kindly replied with an extract of his log-file
showing the DCF77 transmission was fine, but noted that the time carried by
the phase-modulated carrier of the BBC's 198KHz Long Wave radio signal was
early by about 0.9 of a second!

I mentioned this to a contact at the BBC who looked into the problem.
Apparently some equipment had been temporarily replaced earlier in the year
as it would have failed at the GPS week-number roll-over event.
Unfortunately said new equipment hadn't been perfectly configured, with the
observed result.  A completely new system is to be installed next year, but
in the meantime the configuration problem has been corrected, so the BBC
signal should be "perfect" again!

Thanks again to Pieter-Tjerk for bringing this to our attention - goes to
show that "amateurs" can still provide a useful service :-)

    Regards,

         Peter


On Wed, 30 Oct 2019 at 22:15, Pieter-Tjerk de Boer <p.t.deboer at utwente.nl>
wrote:
>
> Hello Peter,
>
> While monitoring DCF77, MSF, and other longwave time signals during the
> DST change this weekend, I did not observe any irregularities.
> I don't have a recording of the raw signals, but here is the decoded data,
> including reception timestamps in the last column:
>
> BBC:                 00:58        1572137879.092676
> DCF77_PM: 2019-10-27 02:58        1572137880.001366
> DCF77_AM: 2019-10-27 02:58        1572137880.001398
> TDF:      2019-10-27 02:58 +0200  1572137880.001817
> MSF:      2019-10-27 01:58 +0100  1572137880.002950
> RBU:      2019-10-27 03:58 +0300  1572137880.006877
>
> BBC:                 00:59        1572137939.092602
> DCF77_PM: 2019-10-27 02:59        1572137940.001373
> DCF77_AM: 2019-10-27 02:59        1572137940.001407
> TDF:      2019-10-27 02:59 +0200  1572137940.001608
> MSF:      2019-10-27 01:59 +0100  1572137940.002951
> RBU:      2019-10-27 03:59 +0300  1572137940.006869
>
> BBC:                 01:00        1572137999.092559
> DCF77_PM: 2019-10-27 02:00        1572138000.001382
> DCF77_AM: 2019-10-27 02:00        1572138000.001419
> TDF:      2019-10-27 02:00 +0100  1572138000.001550
> MSF:      2019-10-27 01:00 +0000  1572138000.002903
> RBU:      2019-10-27 04:00 +0300  1572138000.006862
>
> BBC:                 01:01        1572138059.092783
> DCF77_PM: 2019-10-27 02:01        1572138060.001379
> DCF77_AM: 2019-10-27 02:01        1572138060.001415
> TDF:      2019-10-27 02:01 +0100  1572138060.001530
> MSF:      2019-10-27 01:01 +0000  1572138060.002906
> RBU:      2019-10-27 04:01 +0300  1572138060.006861
>
>
> BBC is the phase modulation on their 198 kHz AM transmitter, encoding UTC.
> DCF77_PM and _AM are the phase and amplitude modulation of DCF77 on 77.5
kHz.
> TDF is the French 162 kHz signal.
> MSF is 60 kHz from the UK.
> RBU is 66⅔ kHz from Russia, where no DST change was made this weekend.
>
> The last column is the reception time as a Unix timestamp, w.r.t. a
LORAN-synchronized clock.
> Clearly, the BBC signal is about 0.9 s early; the others are slightly late
> due to propagation time from their transmitters to my receiver location
> (Enschede. The Netherlands).
>
> Regards,
>   PieterTjerk, PA3FWM
>
>
> On Mon, Oct 28, 2019 at 06:26:05PM +0000, Peter Vince wrote:
> > Was anyone here monitoring DCF77 during the summer-time change this
> > weekend?  An acquaintance has recently modified his code that receives
MSF,
> > and noticed an anomaly - his log shows the minute 02:59 CEST was
missing.
> > It seems tremendously unlikely that there was any kind of fault with
DCF,
> > but sadly he doesn't have a recording of the actual RF signal, just his
> > decoder output.  So I was just wondering if anyone else noticed anything
> > untoward, or maybe even, does anyone have a recording of the signal
itself?
> >
> >      Thank you,
> >
> >           Peter