Allan deviation nist

1. How do you calculate Allan deviation?
2. How do you interpret Allan deviation?

How do you calculate Allan deviation?

Standard deviation is the square root of variance. So to get Allan deviation from Allan variance, we just take the square root of every variance measure we calculated above.

How do you interpret Allan deviation?

An Allan deviation of 1.3×10−9 at observation time 1 s (i.e. τ = 1 s) should be interpreted as there being an instability in frequency between two observations a second apart with a relative root mean square (RMS) value of 1.3×10−9. For a 10-MHz clock, this would be equivalent to 13 mHz RMS movement.