[time-nuts] timelab

[Magnus Danielson]

Hi Ron,

On 07/05/2012 07:12 AM, Ron Ward wrote:
> Hi:
> I am also new and would like information about ADEV, MDEV, HDEV, TDEV,
> Phase and Frequency Difference.

You can start of with the Allan Deviation article on Wikipedia. It has 
the focus on ADEV, from that the modified Allan Deviation is achieved by 
simply averaging the input. The Hadamard uses the third degree 
derivative of the phase data, when Allan only uses the second, and that 
helps overcome the linear drift sensitivity that Allan variance has, but 
providing essentially the same scale. The Hadamard is also available in 
the modified form to achieve the same distinction of frequency flicker 
and frequency white noise that MDEV does. TDEV is really a time 
stability measure rather than the frequency stability measure that the 
ADEV is, it is defined out of MDEV but in reality you can use ADEV 
measures for higher taus.

NIST TN1337 is still highly recommended reading, but it is drinking from 
the hose. NIST SP 1065 is also recommended.

If there is something on the Wikipedia article that can be improved, 
please let me know.

Oh, welcome Ron! :)

Cheers,
Magnus