The Real-time Simulation And Hardware Implementation Of Narrowband Active Noise Control System

Noise is generated by the vibration of objects,which always disturb human beings.The narrowband active noise control(ANC)system copes with narrowband noise whose energy is concentrated at certain frequencies.Frequency mismatch(FM)is usually brought into the the narrowband ANC system and hence significantly degrades the noise reduction performance,as a non-acoustic sensor is used in the system.In addition,transition of the primary noise signal frequency,namely,non-stationary is another problem in the system.In this thesis,the theoretical simulation and hardware implementation on narrowband ANC system are investigated.Firstly,in theoretical simulations,this thesis constructs a real-time simulation platform based on the real-time simulation function of MATLAB/Simulink for feedforward narrowband ANC system.The performance of traditional narrowband ANC system for noise reduction as well as performance in the presence of FM are analyzed through the simulation platform.The traditional and an improved FM accommodating methods are simulated and taken performance comparison for FM problem.Non-stationary scenarios are further introduced into the FM accommodating systems and their performance are comparatively evaluated.Secondly,the hardware for narrowband ANC system is designed and implemented.On the basis of real-time simulation,this thesis designs a narrowband active noise controller with high speed and floating-point C6000 series DSP chip.Taking an one-dimensional duct as the experimental platform,we realize the acquisition and conversion of primary and secondary noise signals,identification of secondary channel,execution of relevant ANC algorithm,and then make the secondary noise signal and primary noise signal going to destructively interfere to finally achieve the goal of noise reduction.Experiments are respectively carried out with traditional narrowband feedforward ANC system and frequency compensation system based on AR model,which verifies the effectiveness of noise reduction of the two systems.