Development of parallel path difference algorithm for active noise cancellation
Active noise cancellation is a new technology for noise control. It reduces the unwanted noise by generating another out-of-phase noise so that the two result in destructive interference. Because of the changing nature of noise signals and environment, sophisticated adaptive signal processing techniques have to be used to achieve good results. High speed digital signal processors are also required to implement these complicated algorithms. A particularly difficult problem in the commonly used active noise cancellation configuration is the on-line system identification of the auxiliary path and error path, required for the proper convergence of the LMS algorithm for noise cancellation. The algorithms already proposed are not satisfactory. A new algorithm, using a "parallel path difference" scheme, is developed theoretically. It splits the input signal into the odd and even numbered sequences by switching between two paths and calculates the error path using the difference of the signals from the two paths. Simulation results successfully prove the validity of the theory and the feasibility of the new algorithm. Steady state and dynamic performance are analyzed.