FIR_LowPass

Author : P Boyle, B F Schutz

Version : 2.0

Input Types :  SampleSet
Output Types : SampleSet
Date : 23 February 2002 

Contents


Description of FIR_LowPass

The unit called FIR_LowPass applies a time-domain FIR filter to the input data set. The user can choose the order of the filter (number of points) and the upper frequency limit on the passband. The user can also choose whether to smooth the filter with a window function in the time-domain.

The filter is constructed from an ideal low-pass filter in the frequency domain, converted to the time domain, truncated to the chosen number of points, and multiplied by the chosen window function. The resulting filter is convolved in the time domain with the input data set.

The user can choose whether to continue the convolution across successive input data sets. In this case the unit will remember enough of the previous data set to provide continuity of filtering, as if the two sets had been concatenated before filtering.

For more information, see the help file on time-domain filtering in Triana.
 

Using FIR_LowPass

FIR_LowPass' parameter window (double-click on the unit) is used to select the upper bound on the pass band, in Hz; the order of the filter (number of points used in the time domain computation); and the windowing function used to smooth the edges in the time-domain. The check box allows the user to determine whether to treat successive input data sets as if they were a single concatenated one to which the filter is applied in a continuous way.