Method of designing polynomials for controlling the slewing of adaptive digital filters

A method for providing filter coefficients in a digital filter in an electronic unit having a digital signal processor, said digital filter having a plurality of reconfigurable filter sections to achieve a desired bandwidth characteristic between a first characteristic with a first cutoff frequency and a second characteristic with a second cutoff frequency, said method comprising the steps of:

• determining a first set of filter coefficients for providing said first characteristic;
• determining a second set of filter coefficients for providing said second characteristic;
• determining a third set of filter coefficients for providing a third characteristic having a third cutoff frequency between said first and second cutoff frequencies;
• determining a polynomial having solutions substantially matching said first, second, and third sets of filter coefficients with respect to an index varying from a first index value to a second index value corresponding to said first cutoff frequency and said second cutoff frequency, respectively;
• storing said first and second sets of filter coefficients and said polynomial in said electronic unit;
• determining said desired bandwidth characteristic during operation of said electronic unit;
• determining an index value corresponding to said desired bandwidth characteristic;
• calculating a set of filter coefficients in response to said index value and said stored polynomial;
• and
• loading said calculated filter coefficients into said filter sections.