Research And Realization Of Speech Signal Processing In Vehicle-Carried Communication Controller System

Nowadays, the military communication equipments have been complicatedly & miscellaneously interconnected hard to operate so the demand of network and systematization of military communication. The vehicle-carried communication controller system can make interconnection among different communication systems conveniently, and implement coordinated communication and command across the different arms of services possible. As a technical method of man to exchange information,speech communication is being used more and more .However,with its application being enlarged, some acoustic problem faced in speech communication is prominent increasingly,including echo cancellation,speech enhancement,speech detection,audio signal coding and decoding. If the above problem cannot be coped with well,they will sometimes debase badly the quality of communication. Therefore,the speech processing unit is an important part of the vehicle-carried communication controller system. This paper describes the general situation of vehicle-carried communication controller system, and then emphasis on the hardware and software design of speech signal processing,of which echo cancellation is focused on especially. By using the DSP chips TMS320VC5509,echo cancellation,speech enhancement,speech detection , audio signal coding and decoding can not only successfully accomplished,but also has many adavantages,such as flexible algorithm programming,economic circuit designing. The fundamental of echo cancellation is employing an adaptive filter to identify and simulate the real echo paths. The performance of an echo cancellation algorithm can be measured by some factors,such as the accuracy of the obtained solution with respect to the theoretically expected set up; the convergence speed; the robustness to round off error accumulation and computational complexity etc. With increasingly more signal processing power available of DSP in recent years, the application of an adaptive filter in real time become economically feasible. Being taken a simple but steady NLMS algorithm,the in-car echo disturbance can be alleviated by 20 db. This basically meets the operating demands.