Research On Active Noise Control System Of Pipeline Based On DSP

The influence of noise pollution on people's lives is getting more and more attention.Noise control methods include passive noise control and active noise control.Passive noise control methods can not have a good noise reduction effect for low frequency noise and the equipment is too large,the cost is also high.But the active noise control technology has a good effect on low frequency noise,and the device is small and easy to install.Active noise control technology is especially suitable for the environment of the limited space like pipeline.For the active noise control of the pipeline,the adaptive filter is often used in order to cope with the variability of the noise signal.The least mean square filtering algorithm is the most commonly used algorithm in the adaptive algorithm.The performance of the algorithm will have a great impact on the actual noise reduction.This dissertation studies the structure of the active noise control system and discusses the different characteristics of noise control structure and application scenarios.We have analyzed the principle of adaptive filter.The least mean square algorithm is studied.The dissertation explains the contradiction between the convergence speed and the steady-state error of in principle.The variable step size LMS algorithm is studied deeply.The dissertation proposes three step control principles.We use the idea of subsection to control the iteration process step by step.In the initial stage we use the fixed-step that can get the fast convergence.And in the steady-state phase we use the secant function to control the steady process,so the algorithm has smaller steady-state error.Through simulating the improved algorithm and comparing with the existing algorithms,the new algorithm has faster convergence speed and smaller steady-state error.On the basis of algorithm research,with DSP as the control core,the corresponding input and output equipment is selected.The feedforward active noise control system is set up.The secondary channel problems in the actual system are modeled.Because of the secondary channel impact on the system,the FXLMS algorithm is used to solve the problem of the secondary channel.The new variable step size algorithm is used to eliminate the noise of pipeline.The results show that the system has a certain noise reduction effect.