[time-nuts] Allan deviation

WarrenS warrensjmail-one at yahoo.com
Sat Mar 13 18:08:23 UTC 2010


>Any one of the counters listed above can do this measurement,

A decent time nut Allan Deviation needs to have noise floor of below 1e-12.
To do this for a 1sec ADEV, it needs a resolution of under 1ps, so NO not all the counters can do that.

ws

********************


On Mar 13, 2010, at 10:23 AM, Raj wrote:

>> From KO4BB page
> http://www.ko4bb.com/Timing/FAQ-1.php
> 
> What exactly would we be measuring unless we compare our standards to a perfect standard ?
> 
> Maybe be a jittery oscillator with a slow drifter on a walkabout. :-)
> 
>> The Allan Deviation is typically computed from a series of Time Interval (TI) measurements against a reference oscillator. Any one of the counters listed above can do this measurement, which simply is the measure of the delay between a signal on Input A (Start channel) and another signal on Input B (Stop channel). 
> 
> 73 & a great weekend!
> 
> -- 
> Raj, VU2ZAP
> Bangalore, India. 


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