[time-nuts] DCF77/PZF correlation after outage

[Martin Burnicki]

Ben,

sorry for the late reply due to the Easter holidays.

Ben wrote:
> Hi Group,
>
> At the 14th of april 2014 between 17:00 and 18:00 hours UTC there was a
> DCF77 outage.
>
> I have a NTP server with DCF77/PZF receiver (lantime m200) which i
> monitor. I noticed that the PZF correlation is slowly comming back to
> nomal (>90%) level, instead of after a few minutes just like the field
> strength level. Below are links to my graph and the Kiel VLF monitor graph.
>
> Field strength and PZF Correlation graph:
> http://imgur.com/gdosBhs

Hm, the description embedded in the graph says the *yellow* line shows 
the *correlation* which is immediately coming back after the outage, as 
expected.

The blue line sould be the "field strength", which is indeed increasing 
very slowly. I'm not sure how you have extracted the field strength from 
the M200, but this is probably only some AGC control value which just 
needs to be sufficient to yield proper correlation. There is no 
parameter available in the LANTIME which reports the true DCF77 field 
strength.

> Kiel VLF monitor graph:
> http://imgur.com/DC9yDrQ

Several devices running here at the factory (Meinberg) have also 
observed the short outage.

Please keep in mind that unlike the British MSF the German DCF77 
transmitter usually has no scheduled outages, and as far as I know is 
only put out of operation for a short time if there is a really heavy 
thunderstorm.

> I hope someone has an explanation or suggestion I can learn from :)

Best regards,

Martin
-- 
Martin Burnicki

Senior Software Engineer

MEINBERG Funkuhren GmbH & Co. KG
Email: martin.burnicki at meinberg.de
Phone: +49 (0)5281 9309-14
Fax: +49 (0)5281 9309-30

Lange Wand 9, 31812 Bad Pyrmont, Germany
Amtsgericht Hannover 17HRA 100322
Geschäftsführer/Managing Directors: Günter Meinberg, Werner Meinberg, 
Andre Hartmann, Heiko Gerstung
Web: http://www.meinberg.de