A Non-Resonant Acoustic Projector(NRAP) for low frequency studies

A Non-Resonant Acoustic Projector has been developed for generating low frequency acoustic signals with source levels in excess of one acoustic watt from 20 to 55 Hz. The projector frequency and source level are set under program control by an 8 bit processor utilizing a conventional DC Servo loop for frequency control. Projector performance was demonstrated recently at a deep water test facility with the projector sustaining source levels of 171dB re one micropascal at one yard for periods in excess of 12 hours at 288 feet.