The Research Of V90 Modem Algorithms And Their Implementation Based On DSP

It is popular to use Modem for data transfers with Internet. Described as the Standard V90 of ITU_T, the transfer speeds of the two ends are different, that of download is up to 56kbit/s.Based on a brief introduction of the theory and development of V90 Modem, this thesis puts the emphasis on the analysis and research for the key technology of V90 Modem, discusses the applications of the adaptive filter algorithms with V90 Modern. Least Mean Square (LMS) algorithms are discussed in detail when they are used for V90 Modem. With analysis of the relationships of SNR, step size and convergent speed of LMS algorithms, the paper presents the simulated results of adaptive equalization and echo cancellation with LMS algorithms. For Viterbi decoding, the relation between SNR and error ratio is analyzed. This thesis outlines the theories, algorithms and the implementation steps for adaptive equalization, echo cancellation and Viterbi decoding. The implementation of echo cancellation is made based on TMS320C5402 DSK and some significant results are gotten. The results are referential to the research of Modem technology.