A new method of re-timing digital signals

Abstract

It is demonstrated that a re-timing device for binary signals can be realised using digital circuit techniques. The mechanism of regeneration through storage of input information is outlined, and the operating principles of practical systems performing this function are discussed. The input signal requirements are defined to allow design of a, practical regenerating system. Control system theory is then used to select a desired system response function whose steady state and transient performance are analysed. Tests made on the laboratory prototype system show good agreement with the mathematical analysis. Further study of the system is suggested with regard to the use of non-linear response functions in the feedback network, thereby providing an improvement of the regeneration characteristic. It is felt that an important side result arising from the work lies in the development of a digital phase difference comparator. Such a device can conveniently be constructed using integrated circuit techniques - a point of considerable interest to designers of telemetry equipment. Construction of the prototype regenerator constituted a major part of the project work as may be realised from the circuit diagrams involved. For this reason discussion of the principles of circuit operation is fairly comprehensive.