Triana Help Index, Frequency-Domain Filtering in Triana

Time-Domain Filtering in Triana


Index


Triana Units for Time-Domain Filtering

There are a number of units in Triana that perform filtering operations in the time domain. In this help file we list the units and then suggest ways to use them to solve important filtering problems.

The time-domain filtering units are in the SignalProc/Filtering toolbox. They are:

The Filtering toolbox also contains group units that are useful for inspecting filters and deciding which ones to use. These are LookFIR_Band, LookFIR_Low, LookFIR_Hig, SpectFIR_Band, SpectFIR_Low, and SpectFIR_High.

In addition there are units that are useful for display: Grapher, MultiGraph, ImageMapper, and ImageView. For an introduction to frequency-domain filtering in Triana, see the help file Frequency-Domain Filtering in Triana.


Using Time-Domain Filtering Tools

Most of the tools offer the user options in their parameter windows. Naturally, filtering units must be told the frequencies they are to select. In addition, three choices appear in many of the units: "Filter Order...", "Window", "...filter continued across successive input sets". They are explained here.

 

Group Units

The group units provide means of inspecting the filters. The groups called "Look..." plot a graph of the output of a filter on a unit impulse: this is the time-domain impulse response of the filter, and it shows the oscillations or lack of them created by the filter. The groups called "Spect..." plot a graph of the power spectrum of the output of the "Look..." units, which is then the frequency-domain impulse response function. This shows how much spectral leakage there is out of the pass-band. Graphs are displayed with logarithmic vertical axes.

To use the group units, drag them onto the working area of Triana and double-click them to open a separate window showing the individual units, or right-click the group unit and choose "Ungroup" to see all the individual units. Then double-click the filtering unit to get the unit's parameter window, which will allow you to choose the window function that you want to use. Then run the group in Single Step mode.