[ntp:questions] Re: Which public servers for adjustment?

Helmut Wollmersdorfer helmut at wollmersdorfer.at
Mon Dec 20 23:44:01 UTC 2004

Richard B. Gilbert wrote:
> Helmut Wollmersdorfer wrote:

> I'd suggest calibrating against the servers with the lowest delay and 
> jitter and comparing with the calculated propagation delays from DCF77, 
> MSF60, and HBG75

Thx, that's what I wanted to know.

> If you need better time than that your options are to make GPS an option 
> somehow or to buy a rubidium or cesium frequency standard with a clock 
> option and have it calibrated by your national standards laboratory!

For me its more like a hobby than a need. Maybe a oncore GPS in fixed 
position mode and 1-3 satellites visible will give more accuracy and a 
used rubidium standard would be nice. But first I want to tune my 

> I would not use "prefer" unless you are much closer to one of your radio 
> sources than to the other two.

The distance from Vienna/Austria is approximately

DCF ...  590 km, earthwaves, stable signal
HBG ...  788 km, interferences depending on weather etc.
MSF ... 1400 km, skywaves, signal run drifts around a little bit (<1ms)

In normal use "prefer" DCF makes IMHO sense, as it has the smallest 
jitter followed by the similar configured peer in the LAN.

Helmut Wollmersdorfer

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