[ntp:questions] Re: HowTo calibrate system clock frequency using NTP

Daniel Kabs daniel.kabs at gmx.de
Mon Feb 6 12:36:01 UTC 2006

Hello Hal!

Hal Murray wrote:
> What sort of accuracy are you expecting?

I hoped to measure the time drift within (or better than) 1 PPM

> The main contribution to changes in drift is temperature.

Right, I cooled the system down by about 30° and the clock drift 
increased by about half a second per day (measured with Plan B).

> Does your environment have a stable temperature?

As stable as "room temperature" gets :-)

> Are you calibrating your systems in the same location that
> you will be running them in?  (Or calibrating them on a test
> bench and shipping them to a customer?) 

The latter. While the system on the test bench, I wanted to measure the 
time drift in order to calibrate the system clock. I also have a 
temperature controlled cabinet available so I may try this again in a 
more stable environment, if neeeded. But upto now, I am faced with two 
different methodes for gathering the frequency offset: both give a 
precise reading if repeated, but as the results differ, only one can be 
accurate :-)


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