Analysis of Frequency Synthesis Error in Narrowband Feedforward Active Noise Control Systems

This paper analyzes a narrowband feedforward active noise control (ANC) system using internally synthesized sinusoid as the reference signal. The effect of frequency error between the primary noise and the reference signal on the performance of the ANC system is evaluated in terms of noise reduction in steady state. Theoretical analysis shows that the achievable noise reduction is decreased for increased frequency error, but can be improved by using larger step size. These theoretical results are verified by computer simulations of the narrowband ANC system with transfer functions measured from a real experimental setup.