# Allan Variance Freeware

- The program computes the four Stability Standard Deviations of a Time series :
- Overllaping Allan Variance : AVAR
- Modified Allan Variance : MVAR
- Overllaping Hadamard Variance : HVAR
- Time Variance : T-VAR

- The error bar is computed for the values of Sigma(tau) for Five noise Types.
- Fast data loading and fast computation
- Power Spectrum Density plot.
- Automatic detection of the noise type.
- Read numerical data from ascii files with optional text header. Automatic detection of decimal separator.
- Data size is unlimited. Tested with file size greater than 300 MB.
- Produce quality report plots.
- Customize plot : style, color, print preview, resolution control, legend, zoom, scroll, annotations.
- Copy, save and mail plots as images with many options : JPEG, PNG, GIF,PCX, Bitmap, MetaFile.
- Export plot data into TEXT, HTML, EXCEL and XML files.

For more information about the definition of These Variances you may refer to :

- J.Rutman: Characterization of phase and frequency instabilities in precision frequency sources : fifteen years of progress . Proceedings of the IEEE, vol.66, n° 9, Sept. 1978
- D. W. Allan: Time and frequency (time domain) characterization, estimation and prediction of precision clocks and oscillators. IEEE trans. UFFC, vol UFFC – 34, n° 6, Nov. 1987
- E.S. Ferre-Pikal et al. , “Draft revision of IEEE STD 1139-1988 standard definitions of physical quantities for fundamental frequency and time metrology -Random instabilities”. IEEE International Frequency Control Symposium, pp. 338-357, 1997

The program was tested with the test suite data in reference [3].

Download the last (2003) version Alavar52_setup.exe

Download the help file ALAVAR.PDF