Integrated Command, Control, Communication and Information (C3I) Systems have developed a language of their own, drawing heavily on acronyms and information technology terminology, resulting in the impression being given to the uninitiated that either a black art is being practised or at least there is a mystique unknown in other complex systems. No master plan or model exists for C3I systems, and their very existence is predicated primarily on the need to fulfil two basic requirements. First, they exist where there is a need at the highest level of management of an international or national authority, or of a large company, or of a large organization, to exercise real-time optimum use of the total and diverse resources available to the corporate body in pursuit of its mission, charter or commercial goal. Secondly, at the lowest level, C3I systems exist to help an individual, or a machine, or a sensor, to perform a given task or rôle more effectively. The integration of emergency services and the operation of large modern transportation systems are among the civilian systems that stand to gain most from the use of integrated C3I systems.

This paper describes one of the key features of the JTIDS/Link 16 tactical data-link, namely its relative navigation facility. A brief overview of the general features of the JTIDS system is given to provide the necessary background to the navigation aspects, and some mention is made of the message-exchange facilities. The main part of the paper describes how the JTIDS system provides the capability to perform accurate navigation, and discusses the basic principles of its operation. Some applications of the navigation function which enhance operational effectiveness are then described. The following topics are covered:

(ii) JTIDS Architecture

(i) Definition of JTIDS/Link 16

(iii) Principles of Relative Navigation

(iv) Source Selection

(v) The Kalman Filter

(vi) Time Synchronization

(vii) The Use of Relative Navigation

(viii) The Relative Grid