H/V spectral ratio

This tool is used to obtain Horizontal to Vertical (H/V) spectral ratios from any type of vibration signals (ambient vibrations, earthquake…). The example used for explanations is an ambient vibration recording. The reference document for the H/V processing is the SESAME user guidelines, which is strongly recommended for further reading ("Guidelines for the implementation of the H/V spectral ratio technique on ambient vibrations measurements, processing and interpretation" [1], 62 pages, April 2005).

Getting ready

• Download compressed signal file.
• Load and view these downloaded signals.
• Select H/V in menu Tools (alternative ways to start a tool)

Window selection

General sub-tab in Time tab of toolbox

• Make sure you are in the Time tab, and that parameters are as in the example window.

Raw signal sub-tab in Time tab oftoolbox with anti-trigger parameters

• Click on the Raw signal, to check that anti-trigger parameters are as in the example window.

Select pop-up menu

• Click on the Select button and select Auto.

Number of selected windows

• The number of selected windows appears at the bottom right corner of the time tab.

The number of windows should be as in the example.

Selected windows

• Selected windows should appear as green rectangles on the signal viewer.

Processing parameters

Processing tab in toolbox

• Click on the Processing tab, and make sure that parameters are as in the example window.

Output parameters

Output tab in toolbox

• Make sure you are in the Output tab, and that parameters are as in the example window.

Data processing

• Click on Start button at the bottom of the toolbox, whatever tab is displayed.

No selected windows pop-up window

• In case no window selection has been performed, a pup-up window appears.

Simply click on the Yes button and processing will follow its way.

Results

Signal diplay

Signal diplay with colored windows used for computing H/V matching with colours of individual H/V curves presented below

• Selected windows are colored, matching colours in he H/V graphics, i.e. colour of individual H/V curves have the same colour as the signal windows.

H/V curve

Timing tab in toolbox

• The blak curve represents H/V averaged over all colored individual H/V curves The two dashed lines represent H/V standard deviation.
• The grey area represent the peak frequency and its standard deviation. The frequency value is at the limit between the dark and clear areas.

Peak frequency and standard deviation values

* Use the cursor to get values on the H/V curve. The exact value of the H/V peak frequency and its standard deviation may be obtained by sliding the cursor onto the H/V curve title (Strong_peak) in the upper right corner above the graphics.

Saving results

Applicatio

• The blak curve represents H/V averaged over all colored individual H/V curves The two dashed lines represent H/V standard deviation.

Further readings

• Guillier et al. 1998,1999,2002,2003, 2004, 2005a, 2005b, 2005c, 2005d, 2007, 2008, 2009, 2010, 2011
• Chatelain et al. 1985, 1987, 1998,1999,2002,2003a, 2004, 2008a, 2008b, 2009, 2010, 2011, 2012a, 2012b
• Spectral ratios along a profile

• Mapping spectral ratios