Delta-Modulation Coding Redesign for Feedback-Controlled Systems

This paper investigates the closed-loop properties of the differential coding scheme known as Delta-modulation (Delta-M) when used in feedback loops within the context of feedback-controlled systems. We propose a new modified scheme of the original form of the Delta-M algorithm which is better suited for applications where the sensed information is used in feedback. A state feedback controller is implemented with the state estimated by a predictor-based differential decoder. Stability of the resulting closed-loop system (controller-coder-decoder) is studied. These properties (stability and performance) depend on the quantization parameter Delta, which is assumed constant in the first part of this paper. In a further step, parameter Delta is made adaptive, by defining an adaptation law exclusively in terms of information available at both the transmitter and receiver side. With this approach both stability and performance is improved.