Allan variance example

1. What is Allan variance and how is it used?
2. How do you calculate Allan variance?
3. Why do we use Allan variance?
4. How is Allan deviation measured?

What is Allan variance and how is it used?

Allan variance is a statistical analysis tool for identifying various noise types that exist in a signal. Developed in the mid-1960s, the Allan variance was used to measure the frequency stability of precision oscillators. Later, this technique was applied to other areas as well.

How do you calculate Allan variance?

Interpretation of value

Allan variance is defined as one half of the time average of the squares of the differences between successive readings of the frequency deviation sampled over the sampling period.

Why do we use Allan variance?

Allan deviation is widely used for plots (conventionally in log–log format) and presentation of numbers. It is preferred, as it gives the relative amplitude stability, allowing ease of comparison with other sources of errors.

How is Allan deviation measured?

The beat frequency method is the standard method to measure Allan variance, or more precisely to measure the frequency deviation of the DUT from the frequency standard. The total power at the respective offset frequency is read from the spectrum analyzer display.