[time-nuts] Noise types and Allan Deviation

[Tom Van Baak]

> A table indicating the dependence of the ADEV of these phase noise types
> on the measurement system bandwidth would also be helpful.

Bruce,

I've never bothered with the details of measurement system
bandwidth as you describe. A couple of reasons.

1) Almost none of the thousand ADEV plots I've ever seen in
commercial and academic literature ever mentions it. That's
my first clue it might be a "Bruce thing" ;-)

2) It looks like it's a pain to compute, and if it doesn't end up
making any difference then it's not worth the bother.

3) If you take NEQ BW into account you can see when it
makes a difference and, as important, when it doesn't.

Here's a nice example from last week:

http://www.leapsecond.com/pages/tbolt-tc/tbolt-tbolt-neq-1.gif

It's the ADEV of two non-optimized TBolt's against each other
on a TSC 5120A (which allows you a selection of NEQ BW)

The good news for you is that there are data points where the
measurement bandwidth makes a difference. See tau 0.01
and 0.02 for example.

The better news is that for the rest of the plot, all the way from
tau 0.1 to 100 000 seconds, it makes no difference at all, not
even one pixel.

/tvb