FIR_Filter
Author : Bernard Schutz
Version : 1.0
Input Types : VectorType
Output Types : VectorType
Date : 21 Feb 2002
Contents
Description of FIR_Filter
The unit called FIR_Filter applies a direct* FIR filter to the input data
set. The filter is defined by the user giving the coefficients {a(j)},
which are applied to the input data {x(j)} to produce output data {y(j)}by
the formula
y(n) = a(0)x(n) + a(1)x(n-1) + a(2)x(n-2) + ...
This is re-applied at each value of n.
The user can select whether to continue the data values {x(n)} across
the successive data sets. When the algorithm starts on a new data set it
assumes that earlier values of x (i.e. x(-1), x(-2), etc) are all zero.
For more information, see the help file on time-domain
filtering in Triana.
Using FIR_Filter
FIR_Filter's parameter window
(double-click on the unit) is used to set the filter coefficients {a(j)}.
The user enters any number of coefficients, separated by spaces. The order
of the filter is assumed to be the number of such coefficients. The user
can also choose whether to continue the filter from one data set to the
next when the unit is accepting successive data sets. This option is selected
by default. If each input should be treated as a new set then the check-box
should be un-checked. he user must choose the filter coefficients according
to what kind of effect is desired.
*A "direct" filter is applied by convolution on the input
data values. It does not use Fourier techniques. However, the input data
set is allowed to be any VectorType,
so that it could be time-series data or spectral data.