BSA Flow Software Installation and User's Guide - CSI

Figure 6-50 Spectrum and Correlation in the list of
possible new objects
Required input The only input required for the calculation of correlations and spectra is data
samples including arrival time. The data can be raw velocity samples from
the processor, or they can be coordinate transformed into velocity samples
U, V and W.
As long as arrival time information is available for each and every data
sample, correlations and spectra can be calculated.
2D- / 3D- data The correlation and spectrum objects can handle only one arrival time. If you
wish to process data from different velocity channels by a single
spectrum/correlation object, you can either use hardware coincidence (the
velocity channels are in the same group) or software coincidence by a
coincidence object.
6.4.1 Spectrum object
Properties of the Spectrum object
The spectrum object will estimate power spectral density from the raw datasamples
using FFT-techniques, to obtain results as quickly as possible.
The FFT-approach require samples that are equally spaced in time, and to
achieve this, sample/hold and resampling of the raw data is done prior to the
actual FFT-analysis, with the resampling frequency determined as twice the
desired maximum frequency of the calculated spectrum.
The properties of the spectrum object is shown in Figure 6-51.
6-52 BSA Flow Software: Options and Add-ons