Caption: Figure 10: The Allan deviation
curve of the detection system.
The value of bias stability is the flat region at the minimum of the Allan Deviation curve (Wang and Williams, 2008).
Figure 6 depicts the shape of Allan Deviation graphs for accelerometer readings.
The magnitude of each stochastic error can be determined from the data by the Allan deviation analysis.
It can be shown how to obtain the random walk coefficients from the Allan deviation log-log plot result.
Although it is true that some GPSDO units have much better performance than others in terms of Allan deviation for a particular sampling interval, and many commercial units are simply not well designed for use as a frequency standard, the authors are aware of no instances where commercial units give systematic long-term frequency offsets.
(Of course, if a customer needs precise knowledge of the short-term Allan deviation of his/her iodine stabilized laser, this information cannot be obtained without better quantification of the GPS-comb short-term stability.)
where the Allan deviation
[sigma](n) is calculated for a set of k-1 subgroups of n drops, where n = T/k (T is the total number of collected drops).
Moreover, the statistic retains all of the desirable features of the Allan deviation
. The effect of this advance is to cut required measurement times in half, effectively cutting the cost of acquiring the most expensive data point in half.