DP11 IIR notch filter
Second-order IIR notch filter that removes a 1680 Hz beep from audio sampled at 44.1 kHz, implemented in Q15 on the AVR128DB48.
Result
- Around 45 dB attenuation at the beep with minimal effect on the rest of the audio.
- The filter needs only four state variables and five coefficients, against 165 taps in the FIR solution from DP9.
- Verified in MATLAB before implementation in C.
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