Coding techniques to improve the reliability of EMCON transmissions

This paper describes a theoretical and practical investigation into alternative EMission CONtrol (EMCON) communication techniques that offer substantially better performance than in-service systems. The traditional method of multiple re-transmissions makes use of time and space diversity to increase the probability of correct reception of the broadcast messages. Using this as a baseline, we investigate a number of superior strategies based on quadruple redundant transmissions. These schemes are firstly compared theoretically assuming uniform probability of bit error and results from actual channel data follow. The results provide a wealth of information on the relative performance of the EMCON strategies for the test channel, on the relative merits of the modems, and on the usefulness of the theoretical analysis.