4.9.3 Digital Effects Filters
4.9.3.1 Shelf Filters
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TLV320AIC3007EVM Software
The digital effect filters (the biquad filters) of the TLV320AIC3007 are selected using the check boxesshown in Figure 19 . The de-emphasis filters are described in the TLV320AIC3007 data sheet, and theircoefficients can be changed (see Figure 17 ).
Figure 19. Enabling Filters
When designing filters for use with TLV320AIC3007, the software allows for several different filter types tobe used. These options are shown on a tab control in the lower left corner of the screen. When a filtertype is selected, and suitable input parameters defined, the response are shown in the Effect FilterResponse graph. Regardless of the setting for enabling the Effect Filter, the filter coefficients are notloaded into the TLV320AIC3007 until the Download Coefficients button is pressed. To avoid noise duringthe update of coefficients, it is recommended that the user uncheck the Effect Filter enable check boxesbefore downloading coefficients. Once the desired coefficients are in the TLV320AIC3007, enable theEffect Filters by checking the boxes again.
A shelf filter is a simple filter that applies a gain (positive or negative) to frequencies above or below acertain corner frequency. As shown in Figure 20 , in Bass mode, a shelf filter applies a gain to frequenciesbelow the corner frequency; in Treble mode, the gain is applied to frequencies above the cornerfrequency.
Figure 20. Shelf Filters
To use these filters, enter the gain desired and the corner frequency. Choose the mode to use ( Bass orTreble); the response is plotted on the Effect Filter Response graph.
SLAU286 – June 2009 TLV320AIC3007EVM-K 23Submit Documentation Feedback