Calculation of amplitude/phase variations



If you suspect that the amplitude and/or phase of a parameter is variable within different substrings (e.g. representing different years) you might consider to use this tool.
  1. Prerequisites:
    Let us assume that you have a set of frequencies and a certain subdivision of your time string in the attribute "Date". By calculating a least-squares fit for each substring separately you realized that the amplitude of a frequency might be variable.
  2. Press the button "Calculate amplitude/phase variations" in the Fit module.
  3. In the dialog select the attribute in which the subdivision of the time string is located.
  4. Choose the type of variation: 'amplitude variation', 'phase variation' or 'amplitude and phase variations'.
  5. Select the frequency that shows the amplitude variation.
  6. Decide whether you want to improve "all amplitudes and phases" while keeping the frequencies fixed, or to define a "special" selection of variable parameters. If you prefer the latter, then click on special to open a dialog for the definition of the selection.
  7. Press Calculate to start the calculation.
  8. After the calculation has finished the results are displayed in the text box below.