Outside Loop Companded Unity-Bit Differential Coders

Abstract

Unity-bit coders, in the form of deltamodulators (DM) for speech coding have been studied in detail and many different designs have been proposed. The strategy used in all of these coders is to adapt the step size of the coder to suit the input-signal power. A few designs are available in integrated-form from many manufacturers.

In the present paper, we examine a class of unity-bit coders, where, a basic linear coder is used while the input to this coder is constrained or compressed to be within suitable limits so as to have the linear coder operating in its optimal range.

The main advantage with this type of realization is that the linear coder is open for modifications and improvements without the step-size algorithm coming in the way of any such attempts.

Indexing Terms:

• Unit-Bit Coders
• Differential Coders
• Adaptive Deltamodulators