[time-nuts] Oops - wrong URL for tvb plot!

Tom Van Baak tvb at LeapSecond.com
Tue Apr 10 10:46:30 EDT 2007


>> Tom's (tvb) plot I referred to in a previous message is at
>> 
>> http://www.leapsecond.com/pages/3gps/gps-adev-mdev.gif
>> 
>> Sorry for the confusion.
> 
> Phew, I was kind of worried there for a while. The ADEV plot showed three
> straight parallel lines with no tendendency to converge.
> 
> Interesting to (finally) see MDEV used for this analysis.
> 
> Cheers,
> Magnus

Me too. Using ADEV to look at the three receivers seemed like
the obvious thing to do, but then Brooks suggested I look at
MDEV instead and I was very surprised, and pleased, to see
the result. It much better reflects what we all do with GPS
receivers, something Tom Clark first popularized with his VP
TAC a decade ago -- which is to time average the sawtooth
away [ OK, for the purists: not to average away to zero, but
to reduce it somewhat through short-term averaging ].

The other thing about the plot is that it show a nice real world
example where using ADEV doesn't convey the right message
at all; using MDEV is closer to the truth.

/tvb





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