7.1.2 Processing parameters
Frequency Domain
This section presents the processing parameters necessary for computing the H/V ratio. These paramaters can be modified interactively by clicking on the "Processing" tab (Figure 1).
Type of smoothing function
Raw spectra contain a lot of frequency samples (e.g. for 50 s time windows and 100 Hz as sampling rate, the natural number of frequency samples is 2500 and the frequency step is 0.02 Hz). They generally show lot of very narrow oscillations and spikes which alter their readability. Moreover, while computing the ratio H/V, the very small values reached by raw spectra lead to unusual values of the ratio.
For this reason, before computing the H/V ratio, the Fourier spectra amplitude of the three components are smoothed. You can choose between three types of algorithm (see table here below). Note that smoothing the Fourier spectra is not mandatory, but strongly recommended.
You can also use a cosine taper to minimise the border effects due to the windowing of the Fourier amplitude spectra. in this case check the "cosine taper" box and give the appropriate value in percentage inside the empty box.
Different types of smoothing function  

Frequency range for the H/V computation
The Output subsection (Figure 2) helps you defining the frequency range for the computation of the H/V curve. As mentionned above the natural sampling for spectra contain a lot of samples. For H/V output, such a precision is useless and sometimes heavy to handle. Furthermore, comparison of spectra obtained with different time window lenghts (hence with different natural sampling) is not easy.
After computing the raw spectra with the full precision, they are output with a restricted "number of samples" ranging from the "Minimum" to "Maximum". These two limits have to be in agreement with the minimum time window length choosen in "Windowing" tab: at least ten cycles in one time window (e.g. for a H/V between 0.2 and 20 Hz, time window lenght should at least 50 s).
Linear or logarithmic scale controls the distribution of samples along the frequency axis. The recommended scale is logarithmic, and the number of frequency ("number of samples").
Appearance of the H/V output
Here you can upload the setting files for automatic update of the window's appearance of the H/V ratio and Fourier spectra amplitude results.