Mao at 08:39, 12 March 2010

2010-03-12T08:39:13Z

Mao: New page: General tab Setting the window length for an individual analysis window is needed in several contexts. It is needed for both [[Geopsy:_H/V_and_...

2010-03-12T08:38:28Z

New page: thumb|left|300px|General tab Setting the window length for an individual analysis window is needed in several contexts. It is needed for both [[Geopsy:_H/V_and_...

New page

[[Image:FKGeneralTab.png|thumb|left|300px|General tab]]
Setting the window length for an individual analysis window is needed in several contexts.
It is needed for both [[Geopsy:_H/V_and_Spectrum_Toolboxes|Spectrum]] and [[Geopsy:_H/V_and_Spectrum_Toolboxes|H/V]]
computation as well as for any array processing technique, let it be [[FK]], [[HRFK]] or [[MSPAC]].

You will find therefore the '''Window Length''' element in all toolboxes related to the analysis methods mentioned above
within the ''General'' section of the ''Time'' tab. The example shows the ''General'' section of the
frequency wavenumber toolbox. There are (up to) three options provided in a drop box [[Image:FKWindowLength.png|60px]].

* Exactly (takes exactly the time window length as provided in the corresponding editable box - unit is in seconds).
* At least (takes at least the time window length as given in the editable box, if possible it takes more - unit is in seconds).
* Freq. dep. (read: frequency dependent. Scales window length to the center frequency of each frequency band to be processed. The number given in the editable box corresponds to a window length in number of cycles for each frequency band. ''T'' is the center period of the band).

'''Note:''' for [[Geopsy:_H/V_and_Spectrum_Toolboxes|Spectrum]] and [[Geopsy:_H/V_and_Spectrum_Toolboxes|H/V]] toolboxes,
only the options '''At least''' and '''Exactly''' are implemented. '''Freq. dep.''' is of no use in this context. On the contrary,
currently for array processing toolboxes [[FK]], [[HRFK]] or [[MSPAC]], the most reasonable and only implemented setting
for the ''Length'' parameter in the context of narrowband dispersion curve processing
is '''Freq. dep.'''. This option relates the window length to the center frequency of each frequency band to be processed.
The absolute window lengths for analysis are therefore linked to the settings in the [[frequency selection]].

Example: for a frequency band with center frequency 2.5 Hz, the central period is 1/2.5 = 0.4 s. Therefore, with a frequency dependent ''Length'' setting of ''30.00 T'', the window length will be chosen as 12.00 s.
In upcoming versions of [[geopsy]] software, this combo box entries in the different toolboxes will be adjusted
to the reasonable options.

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@@ Line 17: / Line 17: @@
 for the ''Length'' parameter in the context of narrowband dispersion curve processing
 is '''Freq. dep.'''. This option relates the window length to the center frequency of each frequency band to be processed.
-The absolute window lengths for analysis are therefore linked to the settings in the [[frequency selection]].
+The absolute window lengths for analysis are therefore linked to the settings in the [[Geopsy:_Sampling_Frequency|frequency selection]].
 Example: for a frequency band with center frequency 2.5 Hz, the central period is 1/2.5 = 0.4 s. Therefore, with a frequency dependent ''Length'' setting of ''30.00 T'', the window length will be chosen as 12.00 s.

Geopsy: Window Length - Revision history

Mao at 08:39, 12 March 2010

Mao: New page: General tab Setting the window length for an individual analysis window is needed in several contexts. It is needed for both [[Geopsy:_H/V_and_...