Difference between revisions of "Geopsy: H/V and Spectrum Toolboxes: Time Tab"

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== Use ==
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= '''Use''' =
  
 
This toolbox tab contains the parameters to select the part of the signal used for [[H/V_spectral_ratio|H/V]] or [[Spectral_amplitudes|Spectrum]] processing on which window selection is performed.
 
This toolbox tab contains the parameters to select the part of the signal used for [[H/V_spectral_ratio|H/V]] or [[Spectral_amplitudes|Spectrum]] processing on which window selection is performed.
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A third section gives information on the number of selected windows obtained after applying to the signal the parameters of the two precedent sections.
 
A third section gives information on the number of selected windows obtained after applying to the signal the parameters of the two precedent sections.
  
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At the very bottom two buttons indicate wether to [[Geopsy: Load_Toolbox_Parameters|load parameters]] from previouly processed data or to [[Geopsy: Load_Toolbox_Parameters|start]] signal processing.
+
At the very bottom two buttons indicate whether to [[Geopsy: Load_Toolbox_Parameters|load parameters]] from previouly processed data or to [[Geopsy: Load_Toolbox_Parameters|start]] signal processing.
  
  
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[[Image:HV_SPEC_toolb_time.png|thumb|center|400px|''Time'' tab of the H/V and Spectrum toolboxes]]
+
[[Image:HV_SPEC_toolb_time.png|thumb|center|300px|''Time'' tab of the H/V and Spectrum toolboxes]]
 
<br style="clear: both"/>
 
<br style="clear: both"/>
  
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== Global time range section ==
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= '''Global time range section''' =
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Used to select the portion of the signal that will be processed ([[Geopsy: Time_Limits|more informations]]).
+
[[Image:HV_SPEC_toolb_time_global.png|thumb|right|300px|''Global time range'' section in the ''Time'' tab of he H/V and Spectrum toolboxes]]Used to select the portion of the signal that will be processed ([[Geopsy: Time_Limits|more informations]]).
  
−
[[Image:HV_SPEC_toolb_time_global.png|thumb|left|300px|''Global time range'' section in the ''Time'' tab of he H/V and Spectrum toolboxes]]
 
 
<br style="clear: both"/>
 
<br style="clear: both"/>
  
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== Time windows section ==
+
= '''Time windows section''' =
 +
[[Image:HV_SPEC_toolb_time_windows.png|thumb|right|300px|''Time windows'' section in the ''Time'' tab of he H/V and Spectrum toolboxes]]
 
Short-duration disturbances of the signal can be avoided during [[H/V_spectral_ratio|H/V]] or [[Spectral_amplitudes|Spectrum]] processing by using an anti-trigger window selection to remove the transients. The objective is to keep the most stationary parts of ambient vibrations, and to avoid the transients often associated with specific sources (footsteps, close traffic). This objective is exactly the opposite of the usual goal of seismologists who want to detect signals, and have developed specific trigger algorithm to track the unusual transients possibly indicating the start of an earthquake. Here an anti-trigger algorithm is used, which is exactly the opposite: it detects transients and tries to avoid them. For more information on this topic, it it suggested to consult the SESAME user guidelines <ref>Guidelines for the implementation of the H/V spectral ratio technique on ambient vibrations measurements, processing and interpretation, [http://SESAME-FP5.obs.ujf-grenoble.fr], 62 pages, April 2005</ref>. Windows are then processed individually to get H/V or Spectrum curves in all selected windows, which are then averaged.
 
Short-duration disturbances of the signal can be avoided during [[H/V_spectral_ratio|H/V]] or [[Spectral_amplitudes|Spectrum]] processing by using an anti-trigger window selection to remove the transients. The objective is to keep the most stationary parts of ambient vibrations, and to avoid the transients often associated with specific sources (footsteps, close traffic). This objective is exactly the opposite of the usual goal of seismologists who want to detect signals, and have developed specific trigger algorithm to track the unusual transients possibly indicating the start of an earthquake. Here an anti-trigger algorithm is used, which is exactly the opposite: it detects transients and tries to avoid them. For more information on this topic, it it suggested to consult the SESAME user guidelines <ref>Guidelines for the implementation of the H/V spectral ratio technique on ambient vibrations measurements, processing and interpretation, [http://SESAME-FP5.obs.ujf-grenoble.fr], 62 pages, April 2005</ref>. Windows are then processed individually to get H/V or Spectrum curves in all selected windows, which are then averaged.
 +
<br style="clear: both"/>
  
  
−
 
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[[Image:Time_Windows_tabs.png|thumb|right|300px|The four sub-tabs of the ''Time windows'' section in the ''Time'' tab]]
 
This section comprises four sub-tabs:
 
This section comprises four sub-tabs:
  
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* '''General''': window selection parameters
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*'''General''': window selection parameters
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* '''Raw signal''': STA/LTA crieria applied to the raw signal
 
−
 
 
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* '''Filter''': filtering criteria for applying STA/LTA on the filtered signal
 
−
 
 
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* '''Filtered signal''': STA/LTA criteria applied to the filtered signal using the filtering criteria in the ''Filter'' sub-tab
 
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<br style="clear: both"/>
 
−
 
 
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[[Image:Time_Windows_tabs.png|thumb|left|300px|The four sub-tabs of the ''Time windows'' section in the ''Time'' tab]]
 
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<br style="clear: both"/>
 
  
 +
*'''Raw signal''': STA/LTA crieria applied to the raw signal
  
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=== General sub-tab ===
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*'''Filter''': filtering criteria for applying STA/LTA on the filtered signal
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[[Image: HV_SPEC_toolb_time_time_gen.png|thumb|right|300px|The ''General'' sub-tab in the ''Time windows'' section of the ''Time'' tab]]This sub-tab contains the criteria used to select stable signal windows.
 
  
 +
*'''Filtered signal''': STA/LTA criteria applied to the filtered signal using the filtering criteria in the ''Filter'' sub-tab
 
<br style="clear: both"/>
 
<br style="clear: both"/>
  
  
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==== Window length ====
 
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[[Image: HV_SPEC_toolb_time_time_general_popup.png|thumb|left|''Window length'' pop-up menu]]There are three ways to define window length (duration, in seconds) using the ''Length'' pop-up menu
 
−
 
−
<br style="clear: both"/>
 
  
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* '''Exactly''': all selected windows will have the same exact duration.
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== General sub-tab ==
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Choose ''Exactly'' in the ''Length'' pop-up menu and enter the window length (in seconds) in the spin box to the right of the pop-up menu.
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[[Image: HV_SPEC_toolb_time_time_gen.png|thumb|right|300px|The ''General'' sub-tab in the ''Time windows'' section of the ''Time'' tab]]
 +
This sub-tab contains the criteria used to select stable signal windows:
  
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[[Image: Time-time_exactly.png|thumb|left|300px|]]
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*Window length
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<br style="clear: both"/>
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*Window overlap
 +
*Bad sample set-up
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*Anti-triggering set-up
  
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* '''At least''': selected windows will have a duration comprised between two values.
 
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Choose ''At least'' in the ''Length'' pop-up menu and enter the window lengths (in seconds) in the two spin boxes to the right of the pop-up menu.
 
  
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[[Image: Time-time_atleast.png|thumb|left|300px]]
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'''MAIN ARTICLE''': [[Geopsy: H/V and Spectrum Toolboxes: Time Tab: General sub-tab|General sub-tab]]
 
<br style="clear: both"/>
 
<br style="clear: both"/>
  
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All windows which duration is comprised between these two values will be selected, thus possibly resulting in windows with different sizes.
 
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This may be useful so as to keep the most possible windows of a very perturbed signal.
 
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−
 
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==== Window Overlapping ====
 
  
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It is possible for successive windows to be contiguous or to overlap, using the ''Overlap'' and spin boxes.
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== Raw Signal sub-tab ==
 +
[[Image: HV_SPEC_toolb_time_time_raw.png|thumb|right|200px]]
 +
This sub-tab is divided into two sections:
 +
* '''STA/LTA parameters section''' (to the left)
 +
* '''Apply to section''' (to the right)
  
  
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* When the ''Overlap'' box is not checked, contiguous selected signal windows will not overlap.
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A box at the bottom indicates whether or not the anti-trigger is appllied to the raw signal.
  
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[[Image: Time-time_nooverlap_menu.png|thumb|left|300px]]
 
  
  
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[[Image: Time-time_nooverlap.png|thumb|left|300px|Resulting windowing when ''Overlap'' box is not checked]]
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'''MAIN ARTICLE''': [[Geopsy: H/V and Spectrum Toolboxes: Time Tab: Raw Signal sub-tab|Raw Signal sub-tab]]
 
<br style="clear: both"/>
 
<br style="clear: both"/>
  
  
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* When the ''Overlap'' box is checked, contiguous selected signal windows will overlap by a chosen percentage entered in the neighboring spin box.
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== Filter sub-tab ==
  
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[[Image: Time-time_overlap_menu.png|thumb|left|300px|]]
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[[Image: HV_SPEC_toolb_time_time_filter.png|thumb|right|300px]]
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Contains the filtering parameters used in the ''Filtered Signal'' sub-tab [[Geopsy: Filter|''(more details)'']].
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[[Image: Time-time_overlap.png|thumb|left|300px|Resulting windowing when ''Overlap'' box is checked]]
 
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<br style="clear: both"/>
 
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==== Bad Sample Definition and Use ====
 
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The "bad sample" concept has been introduced for two purposes:
 
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* eliminate clipped parts of recordings (which imply spectrum distorsion)
 
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* introduce some "tolerance" on the sometimes too severe window selection criteria
 
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−
 
 
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A "bad sample" is therefore:
 
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* either a sample with too high an amplitude (above a given threshold)
 
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* or a sample which falls outside the specified [[Geopsy: STA/LTA|STA/LTA]] range.
 
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−
 
 
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[[Image: Time-time_Bad_sample.png|300px]]
 
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* '''Bad Sample Threshold box'''
 
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This box allows to define the amplitude level above which a sample is considered as bad, and should be rejected when looking for usable windows.
 
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To do so, check the ''Bad sample threshold'' box and enter the desired threshold in the spin box. The threshold is defined in terms of percentage of the maximum amplitude observed over the entire signal. (Thus, setting a 99% threshold will automatically eliminate all clipped parts of the recording)
 
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* '''Bad Sample Tolerance box'''
 
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A maximum number of bad samples may be accepted (tolerated) inside windows during the selection process.
 
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Check the ''Bad sample tolerance'' button, and enter the maximum cumulative time (in seconds) reached by all the bad sample that is accepted in each selected window.
 
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'''Warning :''' ''It is recommended to use this option with care, and only when the plain application of default values lead to a very small number of automatically selected windows''.  
 
 
<br style="clear: both"/>
 
<br style="clear: both"/>
  
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== Filtered Signal sub-tab ==
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==== Anti-triggering alternatives and criteria for window selection ====
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[[Image: HV_SPEC_toolb_time_time_filtered.png|thumb|right|300px]]
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The goal of the anti-triggering is to keep the most stationary parts of ambient vibrations, and to avoid transients. User's defined "bad samples" - if any - are also considered as to be avoided.
 
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Two types of anti-triggers may be applied to he signal, both based on [[Geopsy: STA/LTA|STA/LTA]] detection.
 
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[[Image: Time-time_antitriggering.png|300px]]
 
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* '''Anti-triggering on raw signal'''
 
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When the ''Anti-triggering on raw signal'' box is checked, the anti-trigger is applied sample per sample all along the entire signal, using the [[Geopsy: STA/LTA|STA/LTA]] parameters entered in the ''Raw signal'' sub-tab.
 
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* '''Anti-triggering on filtered signal'''
 
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When the ''Anti-triggering on filtered signal'' box is checked, the signal is first filtered using the parameters entered in the ''Filter'' sub-tab, and then the anti-trigger is applied sample per sample all along the entire signal, using the [[Geopsy: STA/LTA|STA/LTA]] parameters entered in the ''Filtered signal'' sub-tab.
 
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All box checking combinations are possible, including both boxes unchecked or checked. In the latter case only samples that fullfill the criteria of both antitriggers are considered as part of a "quadi-stationary" signal. When none are checked no anti-trigger is apllied in the window selection.
 
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It is thus possible to select windows based only on the ''Bad Sample'' criteria, or even no criteria.
 
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'''IMPORTANT NOTICE:''' when using the anti-triggering on the filtered signal, the signal is filtered ONLY for the window selection process.
 
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Later processing (FFT, HoverV, etc...) is performed on the original RAW signal.
 
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In order to process filtered signal the raw signal should first be filtered with the [[Geopsy: Filter|''Filter'']] in the [[Geopsy: Waveform_Menu|''Waveform'']] menu.
 
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=== Raw Signal sub-tab ===
 
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This sub-tab is divided into two sections.
 
−
 
 
−
[[Image: HV_SPEC_toolb_time_time_raw.png|300px]]
 
−
 
 
−
 
 
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* '''STA/LTA parameters section''' (to the left), includes STA length, LTA length, as well as minimum and maximum STA/LTA thresholds [[Geopsy: STA/LTA|''(more information)'']].
 
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* '''Apply to section''' (to the right), indicates to which tracks and which files the anti-trigger is applied.<br/>*  '''H/V display'''
 
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The tracks are displayed at the top of the section, and the files below the "---"
 
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[[Image: HV_Apply_to.png|thumb|left|200px|H/V display of the ''Apply to'' section of the ''Raw signal'' sub-tab in the ''Time'' tab]]
 
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<br style="clear: both"/>
 
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<br/>*  '''Spectrum display'''
 
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[[Image: Spectrum_Apply_to.png|thumb|left|200px|Spectrum display of the ''Apply to'' section of the ''Raw signal'' sub-tab in the ''Time'' tab]]
 
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<br style="clear: both"/>
 
−
 
 
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Simply check the boxes of the tracks and files that are to be processed.
 
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=== Filter sub-tab ===
 
−
 
 
−
[[Image: HV_SPEC_toolb_time_time_filter.png|300px]]
 
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Contains the filtering parameters used in the ''Filtered Signal'' sub-tab [[Geopsy: Filter|''(more details)'']].
 
−
 
 
−
 
 
−
=== Filtered Signal sub-tab ===
 
 
This sub-tab is divided into two sections.
 
This sub-tab is divided into two sections.
  
−
[[Image: HV_SPEC_toolb_time_time_filtered.png|300px]]
 
  
 
* STA/LTA parameters section (to the left), includes STA length, LTA length, as well as minimum and maximum STA/LTA thresholds [[Geopsy: STA/LTA|''(more information)'']].
 
* STA/LTA parameters section (to the left), includes STA length, LTA length, as well as minimum and maximum STA/LTA thresholds [[Geopsy: STA/LTA|''(more information)'']].
Line 187: Line 87:
  
  
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=== Windowing and data flow sub-section ===
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== Windowing and data flow sub-section ==
 
Two boxes and one pop-up menu located at the bottom of the Time windows section are used to control windowing and real time data acquisition flow.  
 
Two boxes and one pop-up menu located at the bottom of the Time windows section are used to control windowing and real time data acquisition flow.  
  
Line 237: Line 137:
 
<br style="clear: both"/>
 
<br style="clear: both"/>
  
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== Number of windows section ==
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= Number of windows section =
 
In the ''Number of windows'' section, underneath the [[Geopsy: H/V and Spectrum Toolboxes|''Toolbox'']] tabs, a pop-up menu and a numerical display are used to show the number of selected windows.
 
In the ''Number of windows'' section, underneath the [[Geopsy: H/V and Spectrum Toolboxes|''Toolbox'']] tabs, a pop-up menu and a numerical display are used to show the number of selected windows.
  
Line 256: Line 156:
  
  
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== Load parameters and Start section ==
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= Load parameters and Start section =
 
The section at the bottom of the ''Time'' tab comprises two buttons.
 
The section at the bottom of the ''Time'' tab comprises two buttons.
  
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To perform user's windowing, click on the ''No'' button.
 
To perform user's windowing, click on the ''No'' button.
  
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== References ==
+
= References =
 
<references/>
 
<references/>

Revision as of 15:47, 25 February 2013

Use

This toolbox tab contains the parameters to select the part of the signal used for H/V or Spectrum processing on which window selection is performed. The two series of parameters are described in two sections:

  • the global time range section
  • the time windows section

A third section gives information on the number of selected windows obtained after applying to the signal the parameters of the two precedent sections.

At the very bottom two buttons indicate whether to load parameters from previouly processed data or to start signal processing.


Time tab of the H/V and Spectrum toolboxes


Global time range section

Global time range section in the Time tab of he H/V and Spectrum toolboxes

Used to select the portion of the signal that will be processed (more informations).


Time windows section

Time windows section in the Time tab of he H/V and Spectrum toolboxes

Short-duration disturbances of the signal can be avoided during H/V or Spectrum processing by using an anti-trigger window selection to remove the transients. The objective is to keep the most stationary parts of ambient vibrations, and to avoid the transients often associated with specific sources (footsteps, close traffic). This objective is exactly the opposite of the usual goal of seismologists who want to detect signals, and have developed specific trigger algorithm to track the unusual transients possibly indicating the start of an earthquake. Here an anti-trigger algorithm is used, which is exactly the opposite: it detects transients and tries to avoid them. For more information on this topic, it it suggested to consult the SESAME user guidelines [1]. Windows are then processed individually to get H/V or Spectrum curves in all selected windows, which are then averaged.


The four sub-tabs of the Time windows section in the Time tab

This section comprises four sub-tabs:

  • General: window selection parameters
  • Raw signal: STA/LTA crieria applied to the raw signal
  • Filter: filtering criteria for applying STA/LTA on the filtered signal
  • Filtered signal: STA/LTA criteria applied to the filtered signal using the filtering criteria in the Filter sub-tab



General sub-tab

The General sub-tab in the Time windows section of the Time tab

This sub-tab contains the criteria used to select stable signal windows:

  • Window length
  • Window overlap
  • Bad sample set-up
  • Anti-triggering set-up


MAIN ARTICLE: General sub-tab


Raw Signal sub-tab

HV SPEC toolb time time raw.png

This sub-tab is divided into two sections:

  • STA/LTA parameters section (to the left)
  • Apply to section (to the right)


A box at the bottom indicates whether or not the anti-trigger is appllied to the raw signal.


MAIN ARTICLE: Raw Signal sub-tab


Filter sub-tab

HV SPEC toolb time time filter.png

Contains the filtering parameters used in the Filtered Signal sub-tab (more details).

Filtered Signal sub-tab

HV SPEC toolb time time filtered.png

This sub-tab is divided into two sections.


  • STA/LTA parameters section (to the left), includes STA length, LTA length, as well as minimum and maximum STA/LTA thresholds (more information).
  • Apply to section (to the right), indicates to which tracks the anti-trigger is applied (top, above the … : Vertical, North, East) and to which file (bottom underneath the … : "Strong Peak").

Simply check the boxes of the tracks and files that are to be processed.


Windowing and data flow sub-section

Two boxes and one pop-up menu located at the bottom of the Time windows section are used to control windowing and real time data acquisition flow.

Time-Time select.png


  • Update box: should be checked when using geopsy for real time data acquisition. Checking the box when no data flow is entering has no effect on the processing.


  • Common box: check this box to force selecting the same windows on all signal tracks, i.e. STA/LTA threshold must be verified simultaneously on all tracks in order to keep a window. When the box is unchecked, STA/LTA threshold must be verified on each track taken separately. There is no need to check this box in H/V processing, as in this case it is automatically applied.


Resulting windowing with the Common box unchecked
Resulting windowing with the Common box checked



  • Select pop-up menu: used to determine which action is undertaken in the windowing process.

When the windowing has not yet been performed with the current parameters, a "*" is displayed besides Select

Select has not been used yet



When the windowing has already been performed with the current parameters, the "*" is no longer displayed besides Select

Select has already been used


The window selection process includes five possible actions.

Options in Select pop-up menu

Auto: windows are selected automatically using the criteria of the General sub-tab of the Time section.

Add: manually add windows. Choose this option and then, with the cursor, select a zone in the signal display where windows have to be added. If an existing window is included in the zone it will not be affected. Note that a window is added only if the criteria of the General sub-tab of the Time section are fulfilled.

Remove: manually remove windows. Choose this option and then, with the cursor, select a zone in the signal display where windows have to the removed.

Inverse: select the windows that were previously not selected. When no windowing has been performed, applying Inverse will select windows all along the signal without applying the windowing criteria.

Clear: automatically remove all windows.

Load: load windows from previous processing stored in a name.log file.


Resulting Auto windowing


Resulting Inverse windowing applied to the above Auto windowing


Number of windows section

In the Number of windows section, underneath the Toolbox tabs, a pop-up menu and a numerical display are used to show the number of selected windows.

Number of windows section

When "all stations" is displayed in the pop-up menu, the number of windows in the numerical display is the total number of windows selected over the entire station set. It is also displayed when a single station is processed.
The number of windows selected in each station of a multiple processing may be displayed using the pop-up menu.

Pop-up menu of the Number of windows section in the Time tab


The number of windows of the selected station appears in the numerical display, and simultaneously the graphic display zooms on the selected station.

Number of windows of the selected station



Load parameters and Start section

The section at the bottom of the Time tab comprises two buttons.

Load parameters and Start section


  • The Load parameters button is used to load parameters from previous H/V or spectrum processing stored in a name.log file (example).
  • Press the Start button to start H/V or Spectrum processing.

If no window selection has been performed, a pup-up window appears.

Pop-up window indicating that no window selection has been performed


Simply click on the Yes button and processing will follow its way with the current Toolbox parameters.

To perform user's windowing, click on the No button.

References

  1. ↑ Guidelines for the implementation of the H/V spectral ratio technique on ambient vibrations measurements, processing and interpretation, [1], 62 pages, April 2005
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