This version (01 Aug 2012 19:33) was approved by William Jahn.
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The Parametric EQ block extends the functionality of the General (2nd-Order) filter with an enhanced graphical filter design tool. In addition, multiple 2-nd order filter stages can be cascaded to create complex filter responses.
This filter provides:
Graphical design of filter response curves.
High order filtering, via cascaded 2nd order filters (maximum of 15)
Independent filter type and settings for each filter stage.
This block is implemented using cascaded biquad filters. See General 2nd-Order Filters (in Algorithm Information) for details about the biquad filter design techniques used by this block.
Filter Control Window:
The window will initially show a single filter control, as depicted in the figure below.
To open the Filter Control Window, Click the icon button:
To add additional filter stages, click the Add Filter button. Up to a maximum of 15 filters can be cascaded. To remove a filter, select the filter in the graph or by clicking its index in the Filter column and press the Remove Filter button.
Each filter's response can be independently adjusted using the graph controls or spin control at the bottom.
To change a filter's characteristics, like “Frequency” or “Boost”, just click on the colored circle on filter graph, and drag to the desirable position. If preferred, any of the parameters can be changed directly from the spin controls.
To change the “Q” factor using the graph, click on the horizontal line control above the colored circle, and drag it left or right, adjusting the filter's width.
In the “Type” column, choose between Low-Pass, High-Pass, Peaking, Tone, IIR, and First Order filters.
The “Sub Type” section is only available for the First Order filter type. In first order mode, you have the flexibility of choosing between two cascaded first order filters in a configuration of Low - Low, Low - High, High - Low, or High - High combinations. The “Active 1” and “Active 2” check boxes also apply to First Order filters only, and allow you to independently enable or disable either of the two first order filters.