Research And Implement Of Adaptive Equalizer Based On DSP

In digital radio communication systems, inter-symbol interference (ISI) is inevitable because of the multipath fading and channel bandwidth limited in data transmissions. ISI caused bit errors at the receiver and reduced quality of transmissions. Adaptive equalization technique can reduce the bit error ratio and trace time-varied channel, which decreases effects of ISI and noise. At present, adaptive equalizer is the most prevalent and effective solution of eliminating ISI at the receiver.This thesis researches the structure and algorithm performance of adaptive equalizer in time-varied multipath fading channel, and implements adaptive equalizer based on floating point DSP. First of all, it elaborates the reasons of ISI and mathematical model in time-varied multipath fading channel, summarizes characteristics of radio channels and introduces the equivalent discrete time model of channels. Then, both LMS adaptive algorithm and RLS adaptive algorithm are introduced in theory, as well as the converging performance and tracking performance of them and their improvement form are analyzed. The model of communication system is established with Simulink of Matlab, so the accuracy and reliability of adaptive equalizer system are verified. This paper also introduces design process of adaptive equalizer system in detail, and expatiates the key module. Finally, adaptive equalizer system has been achieved according to the development board DSK 6713 based on TMS320C6713 DSP of Texas Instruments Corporation, which eliminates ISI and noise in time-varied multipath fading channel with different adaptive algorithms. The result of experiment is analyzed in order to demonstrate performance of adaptive equalizer system. The performance index of adaptive equalizer system satisfied all design requirements. Furthermore, it can be performed with low cost and easy operation comparing with other congeneric products.The code of adaptive equalizer system is written according to software radio thought, which is reused and transplantable in good coding style. It has been proved that this system has good characteristics of maintainability, reliability and adaptability, the parameters of the system is changed flexibly. The product of the thesis could be used widely in digital radio communication systems.