Abstract: An underwater navigation device wherein a flux gate compass provides head difference signals, a doppler navigation sonar provides drift angle signals, which signals are combined by a summer to provide steering correction signals that are displayed by a steering null meter.

Abstract: Relative phase and sensitivity characteristics of individual transducer eents in a long acoustic array are determined by sequentially positioning a transmitting element in predetermined spaced relation to each array element by means of an array holding member and a trough-like spacing member that contains a known transmission medium, driving the transmitting element with a test frequency input signal that is pulsed at a predetermined repetition rate, gating the output signal from the array element under test to an oscilliscope for phase comparison with an adjustably phase shifted version of the input signal, and measuring amplitudes of both input and output signals.

Abstract: An array of circular, acoustic projecting and receiving transducers is deibed, including a stainless steel baffle plate in which the transducers are mounted, each comprising a stainless steel cup containing a disc-shaped piezoelectric element set in low impedance material and covered by a water impedance matching window. Capacitive and inductive tuning means is provided between each receiving transducer and its associated electronics.