GB657314A - Echo ranging apparatus - Google Patents

Abstract

657,314. Echo sounders. BENDIX AVIATION CORPORATION. June 15, 1948, No. 16133. Convention date, July 2, 1947. [Class 118 (ii)] In an echo-sounder, particularly for submarine use, comprising a common transducer for transmission and reception which is periodically shock-excited to cause it to emit mechanical waves, and a series-resonant circuit to which the transmitted and received signals are applied and from across one element of which the signals are passed to an amplifier and recorder, means are provided for damping the resonant circuit when the transmitted pulses are applied thereto, whereby the " ringing " time of the circuit is reduced and echoes from nearby objects may be distinguished from the transmitted signals. The transducer 10 is coupled via autotransformer 11 and transmission line 18 to the series resonant circuit comprising the inductance 15 and condenser 17 which is connected to the amplifying circuit 19. Shock-excitation of the transducer is obtained by means of condenser 61 and gasfilled valve 57 which is normally non-conducting. Cam 51a is continuously rotated to periodically open and close contacts 53. When the contacts close the grid of the valve 57 gives rapidly negative and then returns to earth potential. When the contacts open again the grid is driven positive and the gas-filled valve fires discharging condenser 61 through the transducer circuit. The resonant circuit 15, 17 is also shock-excited and oscillations produced across the condenser 17 are applied to the amplifier 19 and thence to an arrangement providing a continuous record. A neon lamp 20 is effectively connected in parallel with condenser 17 by virtue of its being connected in series with condenser 70 and 32. The lower electrode (as shown) is kept at a positive potential so that when the upper electrode goes negative the lamp 20 fires damping the resonant circuit. Thus the circuit is damped when the grid of the first valve of amplifier 19 goes negative and it is similarly damped when the grid goes positive, due to the flow of grid current. In this way the " ringing " time of the circuit is reduced and the line produced on the record corresponding to the transmitted pulse is shortened enabling echoes from nearby objects to be more easily distinguished. Recorder. The output from the amplifier 19 is applied to a rotating arm 46 at the tip of which is a stylus which produces a mark on the record strip 34 upon the application of a signal thereto. The ship 34 is unwound at a constant rate from a roll 35 and taken up on a roll 36 which is driven by a shaft 37 which is connected by gearing to a motor 49. The arm 46 is also rotated through gearing by the motor 49 in synchronism with the rotation of the cam 51a. Specification 608,513 is referred to.