Research On Adaptive Noise Cancelling Technology Based On DSP Processor

With the rapid development of the adaptive filter theory and algorithm,adaptive filter technology has been extensively applied in recent decades. Especially, the development of digital integrated circuit and computer technology, that provides many superior conditions suitable for adaptive signal processing technology application. Adaptive filter technology is an important part of the modern signal processing, and the object of study focus on the adaptive filtering algorithms and its application. At present, digital noise cancelling system is designed with the high performance DSP as its core, and relevant adaptive filter algorithm, which become a new development trend. So, construction a noise cancellation system based on DSP, and transplanting adaptive algorithms, and realizing high performance noise cancelling function, which has important practical value in noise cancellation field.The paper analyzes the principle of adaptive filter, structure and application firstly, and then makes further study into Least Mean Square (LMS) algorithm and Recursive Least Squares (RLS) algorithm, which are based on the criteria of the Minimum Mean Square Error (MMSE) and least squares (LS). In order to solve the contradiction of the standard LMS algorithm convergence speed between the steady-state errors, the paper proposes an improved LMS algorithm of variable step length LMS algorithm, and which is comparatively analyzed among several existed improved LMS algorithms.Secondly, the paper introduces the realization methods for several adaptive algorithms based on the MATLAB platform, and makes sensitivity analysis for the parameters,which effect on performance of the standard LMS algorithm.Simulation is carried out and analyzed the advantages and disadvantages for the applications of several adaptive algorithms in noise cancellation.Also the effectiveness of the improved LMS algorithm is verified by the actual noisy audio signal for simulation in noise cancellation system.Finally, On the basis of theoretical investigation and simulation, an adaptive noise cancellation system are employed high speed DSP chip TMS320VC5509A, high performance audio decoder chip TLV320AIC23 and related peripheral circuit design; In the simulators mode of integrated development environment CCS3.3, realizing improved variable step length LMS algorithm and standard LMS algorithm;And in the hardware simulators mode, the simple and easy to hardware realization of adaptive LMS algorithm is used .Through the hardware simulators download link, realizing real-time cancel noise processing based on the DSP noise cancellation system.This paper gives the adaptive noise cancellation implement software design flow chart, the relevant register configuration, and the design of each program module,which has very good reference value.