Development and Evaluation of an LPI Figure of Merit for Direct-Sequence and Frequency-Hop Systems

This paper investigates the performance evaluation problem associated with the design of a low probability of intercept system. Two general methods for evaluating the LPI performance are proposed and described: An interception-time figure of merit and a probability-of-intercept figure of merit. The latter of the two was favored and studied in detail. The performances of frequency-hop and direct-sequence systems are evaluated, using the chosen figure of merit, as functions of both constrained and adjustable system parameters. The direct-sequence signal is found to be more difficult to detect than the frequency-hop signal, in general. Comments are made regarding situations where the frequency-hop signal may be more difficult to detect. Design guidelines are specified for determining frequency-hop system parameters that optimize the LPI performance of a system being designed.