[time-nuts] LPRO testing

[Magnus Danielson]

Warren,

On 01/20/2013 09:42 PM, WarrenS wrote:
> Magnus
>
> After you find/fix the working ones, may want to measure their Ageing
> rate, room temperature Tempco, and ADEV.

Oh yes, that will be the interesting stuff once I'm past the initial 
bumps that I anticipate. These are know to have "issues" so I want to do 
a quick diagnosis so I would know how to proceed with each individual of 
them.

> Two example plots attached, one from LadyHeather using a Tbolt with the
> LPRO as it's ref Osc,
> the other is a TimeLab plot using a XOR phase comparator to test an
> undisciplined LPRO.
> To get valid ageing rate and tempco data that is good enough to measured
> a correctly working LPRO,
> using this Tbolt method, need to log at least three days and preferable
> a week or more of data.
> To measure my LPROs' ADEV which is typically ~1e-11 at 1 sec and crosses
> 1e-12 at ~ 200 seconds, a couple hours of data will do.

Once past the initial hurdles, looking at drift and ADEV becomes 
interesting, so will phase-noise.

> TimeLab's freq plot will give a great plot of the LPRO's locked warm-up
> performance.
> For this, depending on the time period and DUT's noise and drift rate,
> I find setting the TimeLab's freq display filter from 10 to 1000 seconds
> works best.

TimeLab exercises will be nice, but I hate to lock up the computer for 
longer runs with the TimePod. I can use the old laptop for TI.EXE exercises.

Cheers,
Magnus