Finite Impulse Response Filters

Author: Optuma Team Last updated: Jul 22, 2021 02:18

Based on the work of John Ehlers, as seen in the September 2021 edition of Stocks & Commodities magazine.

The article describes the topic of “windowing”, a technique used in digital signal processing and statistics. (“When a waveform or data sequence is multiplied by a window function, the result is the part where they overlap, often thought of as ‘the view through the window.’”)

Ehlers’ premise is that using a windowing function can improve the functionality of simple moving averages (SMAs) and other data filters used for trading. The FIR tool has four filters: SMA, Triangle, Hamming, and Hann.


Scripting Function: FIR()

Triangle FIR turning positive:

FIR(SMOOTHSTYLE=Triangle) CrossesAbove 0

Actions & Properties



Copy Data to Clipboard: Will copy the tool’s values to the clipboard which can then be inserted into a spreadsheet, for example, allowing for further analysis.

Add to Toolbar: Adds the selected tool to your custom toolbar.

Apply Settings to All: When multiple FIR tools have been applied to a chart, page or workbook, this action can be used to apply the settings of the one selected to other instances of the tool. This is a great time saver if an adjustment is made to the tool - such as line colour - as this allows all the other FIR tools in the chart, page or entire workbook to be updated instantly.

Copy Tool: Allows you to copy the selected tool, which can then be pasted onto a different chart window.

Move to Back: If the tool is displaying in front of other tools or indicators clicking this action will move the tool view to the background.

Move to Front: If the tool is displaying behind other tools or indicators on the chart, clicking this action will bring the tool to the forefront.

Restore Default Settings: Click this action if you have adjusted the default settings of the tool, and wish to return to the standard properties originally installed with Optuma.

Save Settings as Default: If you have adjusted any of the tool’s properties (colour, for example) you can save the adjustments as your new default setting. Each time you apply a new FIR to a chart, the tool will display using the new settings.

Delete: Deletes the tool from the chart.



Tool Name: Allows you to adjust the name of the tool, as it’s displayed in the Structure Panel.

Bars: Represents the look back period (20 by default).

Smoothing Style: Select between Hann (default), SMA, Triangle, and Hamming.

Plot Style: Select from Dot, Line, Dash, etc.

Line Style: Select from Solid, Dash, Stippled, etc.

Line Width: Adjust the width of the tool.

Colour Scheme: Adjust the colour of the tool.

Line Colour: Adjust the colour of the tool.

Zero Line Style: Adjust the colour, width, etc of the zero line.

Offset: Moves the tool forward or backwards in time. The offset is measured in bars, so a value of 2 will push the tool forward 2 bars and -2 will move the tool back 2 bars.

Tool Transparency: Use this slider bar to adjust the transparency of the tool. Moving the slider to the left will increase the transparency of the tool.

Visible: Un-tick this checkbox to hide the tool from the chart.

Show in Price Scale: When selected, the current FIR value will be displayed in the Price Scale.

Lock Tool: When selected, any changes to the tool will be prevented from being made.