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How to open the *.max file, created by F-K analysis.

Time window does not show the any plot, why?

.max files produced by FK and other tools can be analyzed by max2curve. The other tools that produce .max files are the SPAC and HV TFA.

max2curve takes values as input (samples from the statistical point of view) measured for each frequency band and builds a normalized histogram for each frequency. Then you can extract the average and the standard deviation per frequency. max2curve is distributed within sesarray package. It contains a graphical user interface that helps you filtering and analyzing correctly your results.

Especially for FK, it's dangerous to compute statistics on time windows without having a look at the complete histogram. In some situations (I would say often), you would miss higher modes and you would introduce a bias in the computation of your fundamental (or main) mode, with results in between the two real modes.

About your second question, do you mean that the Time Window browser looks empty? Keep in mind that the plotted grid is the grid really analyzed internally when you click on 'Start'. This grid is controlled by the test frequency (that you can adjust just for visualization, no influence on 'Start' processing), grid step, grid size and v min. The last three have a direct influence on 'Start' processing.

If the plot is blank, look at these points in order:

1. Check that at least one time window exist at the current test frequency. If so there must be at least on in red. If not, you are probably at a too low test frequency (the length of time windows is counted in number of cycles), or you are using too strong criteria to reject time windows (e.g anti-trigger).
2. Set v min to 0. This is not advised for processing but you will be able to view something on the plot. One you get something, put it back to the minimum expect surface wave velocity (~100-150 m/s).
3. Check that grid step and grid size correspond to your array geometry. These values can be deduced from the theoretical array response computed with 'build_array' (also distributed with sesarray). See Wathelet et al. (In press) for more details about how to select these values.