[ntp:questions] Re: Comparing offset of multiple refclock/servers

Ulrich Windl Ulrich.Windl at RZ.Uni-Regensburg.DE
Mon Aug 22 08:51:26 UTC 2005

hmurray at suespammers.org (Hal Murray) writes:

> Back to UPSs.  It might be interesting to try a measurement near
> the ones that don't cause problems.  My guess is that they are
> trashing some other frequency.  60 KHz is pretty old for switching
> power supplies.  Small ones are in the MHz now.

One reasons why DCF77 does no longer work here is the setup of a MGE Comet S31
(10kVA UPS). As I learned, that UPS uses pulse width modulation, effectively
causing to overlay the DCF77 signal by some magnitudes. Talking to MGE tech
persons I learned that they "don't know of any problems", and "they will not
change their design". Effectively this means that no DCF77 will work within 50
meters of such an UPS.


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