The generalized sinusoidal frequency modulated waveform for continuous active sonar

Continous Active Sonar (CAS) system are bi-static systems that transmit high duty cycle waveforms so as to constantly process target echoes and revisit the target scene more frequently than conventional Pulsed Active Sonar (PAS) systems. This paper presents novel pulse train waveforms and adaptive processing methods for CAS systems. The pulse trains are composed of Generalized Sinusoidal Frequency Modulated (GSFM) waveforms that are nearly orthogonal to each other even when occupying the same band of frequencies. Additionally, three processing methods are introduced that trade off Coherent Processing Interval (CPI) with target acceleration tolerance while revisiting the target scene every Pulse Repetition Interval (PRI). Simulations demonstrate the pulse trains waveform designs and processing methods and show that certain pulse train designs also mitigate interference from the transmitted acoustic signal, known as the Direct Blast (DBL).