Easy HVSR > Graphics > Average spectra

Average spectra

The graphic of the average spectra represents the average of the calculated spectra for each of the directions.

During the analysis process (see the technique description), the windows are subjected to Fourier transform which then generates a spectrum for each window. By averaging for each frequency of the spectrum of each window for the single trace, is obtained the average spectrum for the trace itself. Performed the same operation described above for all the directions is obtained the graphic of the average spectra.

The usefulness of this graphic is the ability to verify that there are no sources with content in specific frequencies and at the same time that they have a periodicity. In practice, provides information about the quality of the recording: a good recording should show a graphic of the average spectra in which the curves of the spectra exhibit the same trend, so to establish that there are conditions which affect the hypothesis of environmental noise sources (a peak in a particular frequency would indicates the presence of a source that disturbs or obscures the others).