Spectra and picking¶
Computing the spectrum¶
Set f min, f max, v min, v max and dv, then press Calcola (Compute). The Nyquist frequency is shown at the top right: f max must stay below it. Steps too fine over wide ranges are refused with a message.
The map has frequency on the x axis and phase velocity on the y axis. Where a real wave exists a ridge forms: read left to right it descends, and it is the dispersion curve you are looking for.
Colours and Levels change the drawing only, not the calculation.
Apparent curve and regression¶
The maxima of each column appear over the map: blue if used, orange if excluded. The black curve is the polynomial of the chosen degree (2 to 10). Maxima equal to the curve's minimum or maximum drop out of the regression by themselves.
With Escludi (Exclude) drag a rectangle over points to remove, Includi (Include) puts them back, and Reincludi tutti clears all exclusions.
Picking¶
The picking is the list of (f, v) points that enter the inversion. Each point belongs to a mode: 0 is the fundamental, 1 to 4 are the higher ones.
| Tool | Gesture |
|---|---|
| Aggiungi (Add) | click on the map; drag vertically to widen the uncertainty bar |
| Sposta (Move) | drag a point |
| Elimina (Delete) | click on a point |
| Automatico (Automatic) | N. points on the ridges of the map, also on several modes |
| Nuova selezione (New selection) | clears the picking, after confirming on the page |
Below the chart you read f, v and the wavelength λ = v/f at the cursor.
Picking is your choice
Automatic follows the ridges of the map, not the physics. Check it on the map: taking a higher mode for the fundamental overestimates Vs.
The table¶
Curva di dispersione (Dispersion curve) lists the points of the current mode. You can correct f, v and mode; Del on a
cell removes the row. Pasting rows f⇥v or f⇥v⇥mode from Excel replaces the whole picking. Copy sends the points
to the clipboard.
Synthetic model¶
Write a trial layered profile and Mostra curve (Show curves) draws the curves it would produce over the map. It helps judge at a glance whether a profile is plausible.
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