[time-nuts] suitable statistics for measurements with gaps

[jimlux]

On 4/22/16 12:41 PM, Hal Murray wrote:
>
> jimlux at earthlink.net said:
>> But what about when the observations have gaps? Say you're measuring the
>> frequency of a spacecraft oscillator, and you can only see it for 8  hours a
>> day?
>
> One interesting question...  Can you match up the cycles after the gap?  Is
> your clock stable enough or do you have a slower clock (PPS?) that you can
> lock on to.
>
>

probably can't match the cycles..

It's a sort of generalized question, but say your clock is a OCXO with 
1ppb sort of accuracy, that's 1E-9 in a long term sense, and after 
20,000 seconds of a 10 MHz clock, you'll have accumulated 200E9 cycles. 
If your frequency changed the 1ppb, that's 200 cycles error.

And I think that gets to my underlying question, is such a measurement 
meaningful?  What statistic, other than, say, "frequency error measured 
at 24 hour intervals, with 1000 seconds of counting for each 
measurement", which is sort of like ADEV with tau of 86400, but not really.

And would that really help with understanding of hte underlying 
mechanisms.  For oscillators, knowing that there's a difference between 
1/f^3 and 1/f and 1/1 phase noise and then seeing the output of an 
oscillator helps you to optimize the overall system design. if the white 
noise floor is really high, then improving flicker noise may not help.