Techniques for Equalisation of Speech Channels for High-Speed Data Transmission

Abstract

The main purpose of this project was to identify equalisation strategies which would facilitate efficient transmission of data signals over channels primarily intended for the transmission of analogue speech signals. Such channels include leased "private-wire" and switched telephone network speech paths and h. f. radio speech channels. To this end, a comparative study was made of the relative merits of various transversal filter configurations as the basis for an automatically adjustable data channel equaliser. Automatic pre-set and continuously adaptive coefficient setting strategies were considered and their performance compared. Computer simulation was used wherever possible, thus avoiding much of the effort and expense involved in the construction of actual physical models. The growing use of large-scale integration as a manufacturing process led to special consideration being given to modes of operation which could be implemented using almost entirely digital techniques. As a result of this work, a design has been produced for a highly efficient adaptive equalise which converges rapidly to its optimum condition. .The design uses digital techniques and is based on a modular concept. This makes it extremely flexible in application and yet convenient for implementation using L.S.I. techniques.