Soft dB Opus Suite Data Logger Module - Manual (Page 43)

42
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.