ON IMPLEMENTATION OF CELP CODER/DECODER FOR SPEECH SIGNALS

Abstract

The endeavour to communicate with one is a prime function and the desire to convey one's point of view, to relate one to another, is a never ending process. There are many ways we express ourselves, above all speech has always been the main medium of communication between humans. Today it is becoming an important interface between human and machines and so it has been extensively studied for its form and content. The discipline of speech processing is enjoying tremendous prosperity currently, with the excitement of new challenges. Among various challenges, speech coding has been an important for a long time and it continues with current efforts on lower bit rates to achieve a goal of speech transmission - with the highest possible quality, over the least possible channel capacity, and with least cost. Rapid advancement in Digital Signal Processing & the capabilities of Digital Signal Processors has facilitated the intent to accomplish this goal through ,novel and sophisticated digital methods. The work presented here is an effort for the implementation of such a low bit rate speech coder, using digital methods. 1.1. Need of speech coding: 3,2e.33.3L ,35 Since long back, the advantages of digital transmission of speech signals, over -the analog one, have been well understood. For example, speech in digital form can be reliably transmitted over very noisy channels. Also, digital representation of speech signal is identical to the data of other forms, so a communication network can be used to transmit both speech as well: as-data over long-distances; with no -need to distinguish between them. In addition, with regard to transmission of voice signal requiring security, the digital representation has distinct advantages over analog. Probably the most important advantage of digital representation is, the fact that extremely sophisticated signal processing functions can be implemented using digital techniques, for which there is no realizable counterpart available.in_analog implementation.........