Techniques for Low Probability of Intercept Sonar

Based on the equation of low probability of intercept(LPI) factors of sonar, an implementation strategy of LPI signal transmitted technique and bistatic(or multiple bases) technique is presented for the LPI sonar by combining the sonar′s characteristics and the experiences in LPI radar application.Moreover, five LPI sonar signal design techniques, including low frequency signal technique, great time and bandwidth integrator technique, complex-code technique, random or nonlinear system technique, and time-frequency hopping technique are described with emphasis on the factors of space, time, frequency and power. The characteristics of LPI signal wave are analyzed, and several sonar signals with good LPI performance are designed. Simulation results of descending-frequency comb signal and non-linear frequency modulation (NLFM) pulse series signal demonstrate that the designed sonar signals have good LPI performance.