[time-nuts] Data Collection for Allan Deviation

timeok at timeok.it timeok at timeok.it
Sat Aug 1 08:13:27 EDT 2015

Dear ZZ,

To measure phase noise or Allan deviation or other type of measure you need a Reference to compare the DUT, device under test.
This reference have to be better performances than the DUT we can suppose have to be ten time better than the DUT and in case of a GPSDO a good source can be a Caesium or a Maser.
To measure the AD I suggest an high resolution counter and the KE5FX software TIMELAB.
For the connections: reference connected to the external time base of the counter and the DUT connected to the input of the counter.A GPIB is necessary to connect the counter to a PC.

To have an idea on these measurements please see my setup on: http://www.timeok.it/files/time_and_frequency_house_standard_201r.pdf

I have not a Caesium or a Maser but some good HP5065A rubidium. They performance permit some interesting measurement on the GPSDO.


On Sat 01/08/15 05:44 , zzsilicon at post.com wrote:

> If I have a GPS receiver with output pin of both 1pps & 10KHz, a Rubidium
> clock of 10MHz, and a signal generator. How can I determine their Allan
> Deviation? I know the math formula, but my problem is the data collection.
> I am looking through internet so far. It seems the standard way to
> determine Allan Deviation is to use a reference clock with a few electronic
> devices such as frequency counter. What if I don't have any frequency
> reference or any frequency counter. If I have a Rubidium clock with 10MHz
> output to an o-scope, what values should I record for the time series data,
> in order to determine the Allan variation?
> Thanks for the help!
> ZZ
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