Based On The Low Rate Of Celp Voice Codec Amr Research

Speech Communication is an important and indispensable service of defferent modern communication systems from the very time when the telephone was invented0 With the increasing of network users ~. the integrating and diversifying of network service, the contradications among bandwidth~ system capacity and service quality are more and more obvious, traditional 64kbitls PCM speech coding can not satisfy the requirement of transimit bandwidth which is becoming more and more congested0 So, How to reduce the bit-rate of speech without notablly degrading its perceptual quality is a question placed at the front of the researchers.Taking into account of CELP?s advances and popularity features, the key parts of this paper are placed on it0 From the sytematic view, we discuss in detail some key techniques adopted in CELP, especially analyze several typical speech compression standards which are base on CELPO Taking ITU-T G.729 for example, a dedicated digital telephone system design is discussed, including its hardware design~ software design and key techiques.As a reflection of part of my research work, some innovative improvement thoughts on further reducing the code-rate and decreasing the complexity of vocoders are included in this dissertation By discussing the implementation of hot梥witch function in dual modem in appendix A, we probe into the reliability and efficiency of data transmission0...