Performance assessment of broadband impulsive noise jammers

Abstract

A noise jammer raises the noise level observed by a threat sonar to degrade the sonar's detection performance. In this paper we assess the potential for a specific noise jammer waveform used to countermeasure low frequency active sonars. This waveform is a long duration train of broadband acoustic impulses, each of which has significant low frequency energy. We describe the performance of the impulsive countermeasure on a typical active system processor implementation by comparing experimentally determined receiver operator characteristic curves for the sonar processor with and without jammer energy present. Performance was also determined as a function of pulse intervals. The pulse sequence time series input was synthesized from measurements of high intensity impulses transmitted from a range of approximately 35 Nm in a nominal half-channel environment. Required density functions were obtained from a Monte Carlo simulation involving 1()1\5 iterations of signal, jammer pulses and noise input. The time average power required for the pulse waveform to achieve a specified detection system degradation was found to be 9 dB more than that of a continuous gaussian noise waveform.