Geopsy: Waveform menu
Basic processing that can be applied to an ensemble of signals are all listed in menu "Waveforms". To gain access to it, a signal viewer must be active. It can be any of them: a table, a graphic, a map or a chronogram. Basic signal processing can be applied to a large set of signals using the Waveform menu and the Waveform console without visualizing them, just using the Table Signal viewer.
The waveform menu is closely related to the waveform console. Whenever an item is selected in this menu, the action is executed and logged in the history part of the waveform console. The parameters entered through the dialog boxes are converted into function arguments. The results of the processing is always displayed in the original window. The waveform console can be used interactively to apply several processing tools to a large set of signals in one time.
For instance, the history generated by a Butterworth filter depicted in the figure would be as follow :
filter("Butterworth", "BandPass", 10, 20, 4); save("filter(Butterworth, BandPass, 10, 20, 4)");
The first line is the action itself which filters the signals between 10 Hz and 20 Hz with an order 4. The second line saves the results to a local stack under the name "filter..." given between double quotes. Saving each step is mandatory to undo latest processing. At any time, one can revert to any of the previous states and start again another processing. See waveform console for more details how to play with this widget.
Available basic signal processing tools
Each method is performed in a specific domain (e.g. time or frequency). If the signals of the active signal viewer are not in the right domain, they are internally converted with the Fourier transform before processing. The initial domain is restored after processing. Results of a transformation can be saved permanently into the current Database or exported to a file (Export signals).
Methods that process individually all signals:
- Subtract Value
- Subtract Signals
- Automatic gain control (AGC)
- Phase shift
- Decimate amplitude
- Decimate time
Special methods that process individually all signals:
Methods that process several signals together:
Saving the processed files and restoring the original files
The original signals are never touched by these actions although they disappeared from the display. They can be restored using Revert to original in the Waveform menu or using the waveform console. Even the number of signals in the display may change (e.g. merging signals). Operations are applied to a temporary copy (Geopsy: Temporary Signal), automatically removed once there is no more signal viewer referring to it. To save the processed signals, the signals should be exported. Moreover, the list of the processing can be saved using the waveform console.