Category Archives: Allan Variance

Allan variance, noise, power law, stability


Allan Variance Freeware


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

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  • 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 :

  1. 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
  2. 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
  3. 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



Freeware Noise Generator


With this software you can simulate seven types of noise. The Spectrum of the generated noises has the form :

S(f) = f a

a is a integer in { 2, 1 , 0 , -1 , -2, -3, -4}.

This program generates noise data of the following type :

  • White phase Noise
  • Flicker phase Noise
  • White frequency Noise
  • Flicker frequency Noise
  • Random Walk Frequency Noise
  • Random Walk Flicker FM
  • Random Run FM.

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  1. The size of the generated data is unlimited.
  2. A Simple and powerfull Graphical User Interface.
  3. Save the generated noise in an ascii file.
  4. Very fast save to files. Data bigger than 300 MB are saved in less than 30 seconds
  5. Compute and plot (LogLog) of the Power Spectrum Density of the generatednoise.
  6. Fit of the Power Spectrum Density with a general power low
  7. Copy, print export and edit the generated plots and data.

Download the last (2003) version Alanoise3_setup.exe