DIMUS Processing with Seven‐Element Active‐Sonar Arrays

The aural detectability of a seven element DIMUS array for active sonar has been studied experimentally. The array was simulated with sonar data recorded at sea. It was found that a DIMUS array consisting of as few as seven elements can be effectively used. Doppler detectability is preserved. If the interference consists of reverberation from a pulse having a sinusoidal amplitude distribution, the clipping loss is about 2.5 dB for small signal‐to‐reverberation levels. This loss is independent of the bandwidth of the transmitted pulse. If the interference is local noise, the clipping loss is less than 1 dB. It was also found that when equal pulse lengths are used, the detectability of slow targets is much greater with broad‐band transmission pulses than with conventional Continuous‐wave pulses in reverberation‐limited conditions. The improvement in detection with the broad‐band pulses was preserved with DIMUS.