Abstract: An underwater sound projector system comprises multiple sound projectors, each sound projector being capable of producing acoustic pressures. The sound projectors are held in close proximity such that the sound projectors interact with one another via the acoustic pressures produced. In embodiments, the number and/or spacing of the sound projectors are adjusted based on target performance parameters.

Abstract: An air tank for a self-contained breathing apparatus that incorporates a coil antenna for use in a magneto-inductive system. The coil antenna is formed as a part of the tank. The antenna is embedded within the sidewall of the air cylinder to form the air tank. The self-contained breathing apparatus may include a magneto-inductive device operatively connected to the coil antenna for conducting magneto-inductive communications. A microphone and speaker or headset may be included to facilitate voice communications over the magneto-inductive system.