A magnetostriction echo depth-recorder

A new system of echo depth-sounding is described in which the sound signal is produced and the echo received by high-frequency magnetostriction oscillators. Directional properties are given to these oscillators by means of suitable reflectors directed towards the sea-bed. The echo generates in the receiver high-frequency currents, which are amplified and passed through a chemical recorder. The motor driving the recorder also controls the instant of transmission of the sound signal so that the movement of the recording stylus is synchronized with the r egular sequence of sound signals. Whilst the sound signal travels to the sea-bed and back to the ship, the recording stylus traverses a proportionate distance over the chemically prepared recording paper. Two stains are recorded at each traverse, one corresponding to the zero instant of transmission and the other to the instant of arrival of the echo. As the ship proceeds on its course, a continuous record is made which delineates the cross-section of the sea traversed by the ship. Records are reproduced to illustrate the performance of the apparatus in a laboratory tank and at se a. Good results have been obtained at depths exceeding 400 fathoms. The system is particularly suitable for sounding in very shallow water: a depth of 1 or 2 ft. can be clearly recorded.