geopsy.org

Hello,
I carried out HVSR analysis of ambient noise using different processing software (Geopsy and Grilla, the software tool produced for process Tromino recordings). I compared the results from both softwares (using same recording, same windows and same smoothing) and both present the same HVSR, however I observed that the results of “amplification spectraâ€

Unit of spectra are closely related to the units of the signals themselves. There is no particular operation after Fourier transform except smoothing.

If no conversion factor is provided the basic unit is just 'count'. You can provide a conversion factor from 'count' to Volts (normally the factor given by the digitizer, gains,...) and a a factor from Volts to 'unit' (displacement, velocity, acceleration according to your sensor). The first factor is often read from signal file header automatically. The second must be provided manually. You can view these values in a 'Table' by customizing the fields (details at http://www.geopsy.org/documentation/geo ... html#table). These fields have explicit name (see http://www.geopsy.org/wiki/index.php/Geopsy:database) : CountPerVolt, VoltPerUnit and AmplitudeUnit

Once these values are properly set, the signals are plot with unit equal to m/s for instance.

Plotting mm/s is just a matter of graphical properties. Set Y axis title and set Y axis factor to 0.001.