Sensors & Software pulseEKKO, Product Manual

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Appendix B
219
The average value of all the points in this window is calculated and subtracted from the central
point. The window is then moved along the trace by one point and the process is repeated.
In the initial software releases, high pass filtering was integral to all of the plotting and display
programs. As a result the operator was, in many situations, unaware of this wow or low
frequency component in the data. The raw recorded data, however, always retained this
information.
The following diagram displays a single data trace where Wow has been removed with the
Dewow high pass filter:
The following image displays a data section where Wow has been removed with the Dewow
high pass filter:
Pulse Precursor
The result of high pass filtering can induce two types of artifacts into the plotted data sections.
The first is a pre-cursor to the onset of a pulse (see the following diagrams). When the original