Electromagnetic compatibility of digital communications for naval applications

Digital communication has proliferated in a big way in the previous years. The advantages of digital communication are improved efficiency, better transmission accuracy, better noise immunity, requirement of lesser bandwidth, secrecy, and standardisation of transmission/reception equipment. Digital communication in a shipboard application is used for transmission of voice, data and picture between ships in an operational environment where accuracy, secrecy and immunity to noise/interference is essential. The advent of latest equipment capable of advanced signal processing techniques will result in prolific use of digital communication in shipboard applications. The paper aims at bringing out various aspects of digital communication vis-&-vis the dense electromagnetic environment that exists on a naval platform and their compatibility. The use and applicability of source coding, digital modulation techniques, error control coding and data security in mitigating the electromagnetic interference in a ship borne environment are discussed. The various problems of cochannel/adjacent channel interference and the effect of random/burst noise on a digital communication system are also brought out. Achieving immunity of digital communication to interference by use of various spread spectrum techniques is also discussed.