Owner's manual

9.2 Filter and Integration Tab

The Filtering and Integration tab at the bottom of the main post-processing interface includes two

filter functions that can be applied across the entire selected framework (refer to section 10.3 for

more information about the framework selection).

The Filter function is a generic filtering module while the Integral x(t) function allows making simple

or double-time integration on an acceleration signal. Both functions filter the signal since the Integral

x(t) makes the time integration with a filter.

A streaming technique is used to apply a filter on the entire framework. Both filtering functions use

the current wave file as a source for the filter and save the filtered signal in a new wave file. The

filtering operation starts at the beginning of the framework and is done on the entire framework. If

the current framework does not cover the entire signal of the original wave file, the filtering

operation will generate a smaller filtered wave file that contains only the filtered signal of the

selected framework. In this case and after a filtering operation, the starting point of the framework is

automatically reset to zero and the entire filtered signal is presented on the peak value curve. Note

that the original wave file is always conserved on the PC’s hard disk.

Note: After the filtering operation, the beginning of the signal can be distorted because of the

impulse response of the filter applied. We suggest removing the beginning of the time signal by using

the time extraction function (see section 10.3 for details).

The next two sections describe the filtering functions in detail.

9.2.1 Filter

The Filter function is very useful for removing some frequency components on a group of selected

channels. Some typical tasks that can be done with this function are a DC filter, a notch filter to

remove the 60 Hz and its harmonics and a low-pass filter to remove high-frequency noise for clearer

playback. This function has a filter design interface, which is presented in the next figure.