A New Coded-Modulated Pulse Train for Continuous Active Sonar

Abstract

Continuous Active Sonar (CAS) has some advantages over conventional pulse active sonar, such as larger time-bandwidth product, longer correlation durations, continuous detection and tracking. Recently two kinds of coded-modulated pulse trains were designed as the transmitted waveforms for CAS. The linear frequency-modulated (LFM) waveform is modulated via the Costas sequence to form the LFM-Costas pulse train. Another coded-modulated pulse train is composed of the generalized sinusoidal frequency-modulated (GSFM) waveform. This paper aims at designing a new coded-modulated pulse train by modulating the GSFM waveform with the Costas sequence. By comparison with GSFM and LFM-Costas pulse trains, the simulation results show that the new GSFM-Costas pulse train can provide better detection performance including thumbtack ambiguity function shape and low cross-correlation property, as well as the better performance of reverberation suppression.