GB778673A - Improvements in or relating to echo sounding systems - Google Patents

Abstract

778,673. Echo - sounding. MARCONI SOUNDING DEVICE CO., Ltd. Aug. 5, 1955 [Nov. 2, 1954], No. 31619/54. Class 118 (2). An echo-sounder comprises at least one transmitting transducer and at least one receiving transducer adapted to produce or receive (as the case may be) a pressure wave beam the section of which is narrow in one plane and wide in the section plane at right angles thereto, the said transducers being arranged at a substantial angle to one another, so that although an elongated narrow strip of sea bed is illuminated by the transmitting transducer, echoes from only a short length of this are received by the receiving transducer. In Fig. 1 a ship 2 has a transmitting transducer 1 athwartships and a receiving transducer 5 perpendicular to transmitter 1, each having a rectangular vibrating surface many wavelengths long but only a few wavelengths wide. Thus, at a depth of, say, 100 feet a strip of sea bed 6 ft. by 40 ft. may be covered by each transducer, but since these are at right angles an area only 6 ft. by 6 ft is effectively determined. The transmitter 1 is fed by known electronic circuits 4 and the receiver 5 feeds known receiving and recording apparatus 6 and 7. Thus a narrow strip of sea bed parallel to the ships, path is scanned by motion of the ship. The modification of Figs. 2 and 3 enables a wider strip to be scanned without loss of detail across the strip. A plurality of transmitters 1A, 1B . . . 1E are tilted as shown in Fig. 3 so that, in conjunction with receiver 5, each delineates a narrow strip of the sea bed parallel to the ships, path and continuous with its neighbours. The transmitters are energized successively, the interval between transmissions being sufficient to allow reception of each echo before the next transmitted pulse. Reception and recording is as in Fig. 1. Alternatively, a tilted series of receivers may be used with a single transmitter (Figs. 4 and 5, not shown). In this case each receiver has its individual recorder. If required, the records may be cut-out and stood on edge to provide a three-dimensional contour map of the sea bed. A large area of sea bed may be investigated from a stationary ship by combining the tilted transmitter system with the tilted receiver array. Gyroscopic or other stabilizers may be used to counteract rolling and pitching. The transducers may have curved surfaces to give partial focussing of the beams and increased recording depth with good definition.