TV Converter Box User Manual

4.9.3 Digital Effects Filters
4.9.3.1 Shelf Filters
www.ti.com TLV320AIC3007EVM Software
The digital effect filters (the biquad filters) of the TLV320AIC3007 are selected using the check boxes
shown in Figure 19 . The de-emphasis filters are described in the TLV320AIC3007 data sheet, and their
coefficients 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 to
be used. These options are shown on a tab control in the lower left corner of the screen. When a filter
type is selected, and suitable input parameters defined, the response are shown in the Effect Filter
Response graph. Regardless of the setting for enabling the Effect Filter, the filter coefficients are not
loaded into the TLV320AIC3007 until the Download Coefficients button is pressed. To avoid noise during
the update of coefficients, it is recommended that the user uncheck the Effect Filter enable check boxes
before downloading coefficients. Once the desired coefficients are in the TLV320AIC3007, enable the
Effect 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 a
certain corner frequency. As shown in Figure 20 , in Bass mode, a shelf filter applies a gain to frequencies
below the corner frequency; in Treble mode, the gain is applied to frequencies above the corner
frequency.
Figure 20. Shelf Filters
To use these filters, enter the gain desired and the corner frequency. Choose the mode to use ( Bass or
Treble); the response is plotted on the Effect Filter Response graph.
SLAU286 – June 2009 TLV320AIC3007EVM-K 23
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