Difference between revisions of "Geopsy: Correlations"
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''Correlations'' modifies the [[Geopsy: Temporary Signal|temporary signal]]. | ''Correlations'' modifies the [[Geopsy: Temporary Signal|temporary signal]]. | ||
| − | '''Warning:''' The correlation of signals with a different starting and ending times cannot be computed. | + | '''Warning:''' The correlation of signals with a different starting and ending times cannot be computed. In such a case, it is needed to first [[Geopsy: Cut|cut]] the signals. |
[[Image:CorrelationsEx.png|thumb|left|300px|Example of correlations between signals]] | [[Image:CorrelationsEx.png|thumb|left|300px|Example of correlations between signals]] | ||
Revision as of 09:51, 12 March 2010
Correlations, reached from the Waveform menu, computes the correlations of the signals in the active signal viewer with the requested signals.
Parameters
By clicking on Correlations, a pop-up window appears with the following options:
- Maximum time delay controls the size of the output window. The value m is in seconds. The correlations are displayed between -m and +m.
- Choice of the signal to correlate with the active signals. The possibilities are:
- Between all pairs of signals will compute all the parts of the correlation matrix, i.e. the correlation of each signal of the active signal viewer with each other.
- With a reference signal will compute the correlation of each signal of the active signal viewer with the selected signal in the pop-up menu (one line of the correlation matrix). It is only possible to correlate the signals with one of them.
Correlations modifies the temporary signal.
Warning: The correlation of signals with a different starting and ending times cannot be computed. In such a case, it is needed to first cut the signals.
Use of correlation
Correlation between 2 signals (c.f. Cross-Correlation) is able to give many different informations. First, the maximum in time gives the time delay between two signals. The spectra of the cross-correlations is the cross-power spectra. It enhances the frequencies common to the two signals.
