An investigation of the use of chaotic signals in active sonar

Abstract

Many natural effects are now known to be chaotic rather than random, i.e., are generated by simple non-linear systems. The paper reports the outcome of a theoretical and experimental study to assess whether signals based on chaotic time series offer advantages in active sonar. It is noted that for conventional detection, the detailed structure of the signal is unimportant. Any advantage will come from novel effects due to interactions with the target or the environment. An overview is given of apparently novel behavior in echoes from a resonant target which were first noted in simulations and then observed in laboratory ultrasonic measurements. An explanation in terms of linear systems theory is outlined. The limitations which inhibit the use of advanced non-linear techniques for detection will be discussed and illustrated with reference to the results of analyzing data measured in an outdoor acoustic test facility.