[time-nuts] Re: tinyPFA feature request

[Erik Kaashoek]

Adam,
Both the Timepod and the tinyPFA normally would use all samples over the 
set measurement interval to calculate the phase.
If the phase rotates quickly versus the measurement interval this leads 
to some kind of averaging of the phase over the measurement interval 
resulting in a reduction of the detection of any phase changes with a 
period close to the measurement interval.
Both the Timepod and the tinyPFA solve this by not using the the data 
from the whole interval but only a part of it. Say only the first 10%. 
Any phase change with a period close to the measurement interval will 
now no longer be attenuated.
This reduction in measurement time is similar to decimation used in 
digital signal processing, hence the word decimation is used to describe 
the amount of data that is not used from a measurement interval.
Setting the decimation to 5 in a tinyPFA delivers similar results to a 
Timepod as the Timepod is using similar amount of decimation
Erik.

On 22-8-2023 1:13, Adam MacDonald wrote:
> All,
>
> I’ve been experimenting with the Tiny PFA and it’s an excellent piece of engineering. Thanks Erik!
>
> Not completely understanding the statistics of ADEV, I’ve searched the forum for any information on the decimation that is selectable in the tPFA software. Are there any threads or references someone can point me to on this topic?
>
> Thanks
>
> Sent from my iPhone
>
> Adam MacDonald
> calvinf15 at sbcglobal.net
> 850-460-5535
>
>