Abstract: A sonar receiver comprises an inwardly curved reflector arranged to direct received sonar signals onto a transducer system. The transducer system comprises an array of transducers distributed over an inwardly curved path facing the reflector. Each transducer is responsive to sonar signals received from a particular direction to provide an output signal indicative of a reflecting object, the amplitude of which signal is related to distance of the reflecting object.

Abstract: A sonar bearing determining system comprises a generator for radiating a sonar signal and a receiver for receiving echo signals. The receiver comprises an array of spaced receiving transducers and a modulating and sampling arrangement which consists of a multiplexer driven by a clock signal for producing a combined signal. The combined signal is of the form of a repetitive sequential sample of each of the received signals modulated by a signal equal to the multiplexing signal but phase displaced relative thereto. A bearing determining device is arranged to determine the bearing of an object providing an echo in dependence upon the frequency component of the combined signal or in dependence upon the time displacement of the combined signal relative to a predetermined time value. The modulating and sampling means is arranged to route selectively samples of each of the received signals and thereby to effect both modulating and sampling functions.

Abstract: A target location system comprising a signal transmitter including a pair of signal transmitter transducers arranged in spaced apart relationship and means for driving the transducers with transmitter pulse signals at the frequencies Fo and Fo+Fb respectively which are arranged to increase progressively in frequency during each pulse to Fo+.DELTA.f and Fo+Fb+.DELTA.f respectively where .DELTA.f is equal to or less than Fb, and an echo signal receiver comprising receiving transducer means feeding a filter bank, the filter bank comprising a plurality of filters which cover in aggregate a predetermined frequency band, each filter being adapted to cover one slot or section of the band whereby the bearing of a target from which an echo signal of a transmitter pulse signal is received, is indicated in accordance with the slot or slots in which the echo signal is received.

Abstract: A target location system comprising a signal transmitter arrangement for transmitting pulses the frequency of which increase progressively during each pulse period from a frequency f to a frequency f+.DELTA.