Difference between revisions of "Geopsy: Correlations"
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(New page: thumb|right|200px|Correlations pop-up window '''Correlations''', reached from the Waveform menu, computes the correlations of the sign...) |
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*Choice of the signal to correlate with the active signals. The possibilities are: | *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 [[Geopsy: Signal Viewer|signal viewer]] with each other. | **''Between all pairs of signals'' will compute all the parts of the correlation matrix, i.e. the correlation of each signal of the active [[Geopsy: Signal Viewer|signal viewer]] with each other. | ||
| − | **''With a reference signal'' will compute the correlation of each signal of the active [[Geopsy: Signal Viewer|signal viewer]] with the selected signal in the | + | **''With a reference signal'' will compute the correlation of each signal of the active [[Geopsy: Signal Viewer|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'' | + | ''Correlations'' creates new [[Geopsy: Temporary Signal|temporary signals]] in the active [[Geopsy: Signal Viewer|signal viewer]]. |
| − | '''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]] | ||
==Use of correlation== | ==Use of correlation== | ||
| − | ''Correlation'' between 2 signals (c.f. [[Wikipedia:Cross-correlation|Cross-Correlation]]) | + | ''Correlation'' between 2 signals (c.f. [[Wikipedia:Cross-correlation|Cross-Correlation]]) provides many different informations. The two basic one are the following : |
| + | * 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. | ||
==See also== | ==See also== | ||
*[[Wikipedia:Cross-correlation|Cross-Correlation (Wikipedia)]] | *[[Wikipedia:Cross-correlation|Cross-Correlation (Wikipedia)]] | ||
Latest revision as of 13:53, 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 creates new temporary signals in the active signal viewer.
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) provides many different informations. The two basic one are the following :
- 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.
