Ideal filter
The Ideal filter I/O filters the source's data using an ideal user definable software filter. It fully passes all wanted frequencies in the frequency spectrum and fully blocks all unwanted frequencies in the frequency spectrum. The edges of the filter are infinitely steep.

A typical application of the Ideal filter I/O is to remove unwanted frequencies from a measurement, which may negatively affect further operations on the measured signal.

There are a few restrictions on the use of the Ideal filter I/O:

  • It can only be used with block mode measurements, not with streaming measurements.
  • It works best with a periodical signal, of which an exact full number of periods is measured.


To control the behavior of the Ideal filter I/O, several properties are available. These can be accessed through a popup menu which is shown when the I/O is right clicked in the Object Tree. The properties can also be accessed through its settings window which is shown when the I/O is double clicked in the Object Tree. To open the Object tree, click the Show object tree Show object tree button.

Ideal filter control

By default, the settings window only shows the most used settings. When Advanced is ticked, the extended window with all settings is shown. See also the program settings.


The following filter types are available:

  • Low pass Low pass filter
  • High pass High pass filter
  • Band pass Band pass filter
  • Band stop Band stop filter

Cut off frequency

The Cut off frequency defines the frequency where the where the switch is made between fully passing and fully blocking frequencies. The Cut off frequency is only available for the Low pass filter and the High pass filter.

Center frequency

The Center frequency defines the center of the band that is either passed or blocked. The Center frequency is only available for the Band pass filter and the Band stop filter.


The Bandwidth defines the width of the band around the Center frequency where the frequencies are either passed through or blocked. The bandwidth is only available for the Band pass filter and the Band stop filter.

Common properties and actions

Related information

Multiply / Divide

The Multiply / Divide I/O multiplies or divides data of two ore more sources.


The Differentiate I/O differentiates the source's data.


The Filter I/O filters the source's data using a user definable software filter.

Signal cleaner

The Signal cleaner I/O cleans up a periodical signal by removing noise and other unwanted distortions from the source's data.


The Average I/O averages successive measurements and outputs the average of these measurements.