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 .

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 the H/V toolbox

• Make sure that the H/V Toolbox is displaying the Time tab, and that parameters are set as in the example window.
• To ensure that parameters are set up alright, it is possible to download the compressed parameter file and load toolbox parameters.

Raw signal sub-tab in Time tab of the toolbox with the anti-trigger parameters

• Click on the Raw signal sub-tab in Time tab, to check that the anti-trigger parameters, used to et rid of saturated signal 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.

• More options for selecting windows are available.

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

No selected windows pop-up window

• If 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

H/V curve

• 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.

Changing H/V graphics appearance

Pop-up menu to restore a make-up

• It is possible to change the appearance of the H/V graphics at the user's will using a make-up.
• As an example, first download the compressed make up file.
• Then right click in the left hand margin of the H/V graphics.
• Select Restore make-up in the pop-up menu and then select HV_Makeup.mkup file.

New H/V graphics appearance change after applying a make-up

• The appearance of the H/V graphics is now at the user's taste.

Saving results

Pop-up menu to save H/V graphics

• The H/V graphics may be saved in various image formats.
• Right click in the left hand margin of the H/V graphics.
• In the pop-up menu choose Export image.

Directory were to save H/V graphics

• Choose a destination folder, image format, and file name.