Wave ana

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"Wave_ana" (wavelet analysis) is a program for time series analysis. [1] The program is written in standard Fortran-77 and has been ported to a number of Unix machines. The program has two input menu sections: one to select the input data and to perform some signal manipulation (input menu), and one to analyse the data (analysis menu). The program is interactive, although it can be run in batch mode using a switch in the input file (wave_ana.dat). The program has a built-in help facility.

Input menu

The program can read a number of input signals. The number of signals read is controlled by the Norm/cross/triple input switch ("0" = 1 signal,"1" = 2 signals, "2" = 3 signals). These signals can be text files in a number of formats, or in the TJ-II database format (VXI). Several other but mostly obsolete formats are also available (e.g., unformatted binary data). The input menu also provides options for time window selection, subsampling, additive noise (for testing purposes), data amplitude normalisation (so that the RMS = 1), and, importantly, filtering. A number of filters is available, both FFT-based (sharp in frequency space) and smoothing-based. When several signals are read that are not on the same time base, the signals are resampled onto the time base of the first signal.

Analysis menu

Several analysis options are offered:

  1. Mean, RMS, skewness, kurtosis, probability distribution, cross correlation
  2. Wavelet or Fourier spectrum
  3. Wavelet or Fourier spectrum with time resolution
  4. Wavelet or Fourier bicoherence
  5. Bicoherence at fixed sum frequency
  6. Summed bicoherence
  7. Bicoherence with time resolution
  8. Wavelet cross coherence

Several types of wavelet are available (Morlet, ...)

Program output

The program produces two types of output:

  • ASCII text data files
  • Graphical plots

In batch mode, the graphical output is suppressed. Graphics output routines are available for PV-Wave and for gnuplot.

The program is easily portable and freely available from its author (B.Ph. van Milligen)

References

  1. B.Ph. van Milligen et al, Wavelet bicoherence: a new turbulence analysis tool, Phys. Plasmas 2, 8 (1995) 3017