Digital Speech Interpolation Techniques

Abstract

The problem of optimum utilization of a link of finite capacity has been of interest for a long time. The major effort in this direction, resulted in the Time Assignment Speech Interpolation (TASI) technique albeit a relatively poor method. The drawback was not so much the basic idea, but the difficulty of implementation. The advances in Digital Coding and Digital Signal Processing (DSP) techniques have helped overcome most of the hurdles, and opened up possibilities for other techniques that would not have been possible with the conventional analog methods. Today we have a host of such methods, referred to generically as Digital Speech Interpolation (DSI) systems. In this paper we review some of the better known methods including Campanella's DSI which was the forerunner of the DSI era and present results of some of the recent DSI techniques implemented by the authors. Increase in channel capacity by a factor of at least 2 times can be achieved with little or no loss in quality. With a marginal reduction in quality a tripling of the capacity can be obtained.

Indexing terms:

• Digital speech interpolation technique
• Digital coding
• Digital signal processing