[time-nuts] ADEV on data with gaps

[Lux, Jim]

I've got a series of clock measurements where the actual measurement 
occasionally has problems (e.g. it's measured against GPS, and there are 
GPS partial outages).

What's a strategy for calculating ADEV (and related parameters) where 
there are data in the sequence that are excised? For example, does 
Timelab or Stable32 have a way to have timestamps for the 
frequency/phase measurements that recognizes gaps?

At a first glance, it seems that the calculation for each tau will have 
a different number of measurements contributing.  Say I have 1000 
seconds of data, once a second, and there's a gap of 100 seconds 
somewhere in the middle.  For the 1 second tau, I've got 900 
measurements.  for a 100 second tau, I'll have 800 measurements (because 
for 200, one or the other end point is missing), etc.

Some plots attached showing some data.  In this case, I'm looking at a 
post calculated "clock bias" between GPS and the clock - that is, 
there's a process that estimates the clock offset (in meters). A first 
difference gets rate, and clock has some relatively fixed bias (that 
changes with time), and random variations on top of that.  However, the 
measurement depends on the SNR of the GPS signals (lower plot on 
biasdrift, it's the measurement uncertainty estimate)

At some point, of course, the ADEV measurement is limited by the GPS 
measurement uncertainty - if it's 1 ns, then ADEV is never going to 
measure less than 1E-9 over 1 second.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: biasdrift_rtgx_2024-01-11_20230217T053520.000_edward.tdp.png
Type: image/png
Size: 59988 bytes
Desc: not available
URL: <http://febo.com/pipermail/time-nuts_lists.febo.com/attachments/20230804/69589a98/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: clockratedeltaspike.png
Type: image/png
Size: 33703 bytes
Desc: not available
URL: <http://febo.com/pipermail/time-nuts_lists.febo.com/attachments/20230804/69589a98/attachment-0001.png>