Patent GB-401565-A (GB)
Title: Improvements in echo-sounding apparatus
IPC: G01S15/10
Filed: 1933-03-13
Abstract: 401,565. Echo-sounding and distance-measuring apparatus; fluid supply whistles. LABOUREUR, L. A. M. J., 19, Rue Bonaparte, Paris, and DUBOIS, R., 3, Rue Michelet, AsniÞres, Seine, both in France. March 13, 1933, No. 7618. Convention date, March 11, 1932. [Classes 13 and 118 (ii).] In an echo - sounding apparatus for use on aircraft or vessels for determining respectively the height above the ground or sea bed, the time interval between the emission of the sound and its reception after reflection is measured by a condenser associated with a thermionic valve which permits charging during the interval but prevents discharge. Fig. 1, shows the sound emitting apparatus which comprises a whistle 1 located within a reflector 3 and operated from the air or gas supply 12 through the intermediary of a valve 2. The valve comprises a piston 13 having a port 14 which during the movement of the piston from one extreme position to the other, connects air supply 12 to the whistle inlet 16. Passages 19 are provided in the valve cylinder to prevent the formation of air cushions. Fig. 2 shows the equipment for measuring the time duration between the moment of sound emission and the reception of the echo. The time duration is measured by a milliammeter in the plate circuit of a thermionic valve 21 the current being dependent on the amount of charge absorbed by a condenser 20 during the interval. The condenser is connected in the grid circuit in series with a resistance R 1 across a resistance R2 in a circuit which is adapted to carry constant current during the time interval. The current is maintained constant by a neon lamp 26. Prior to operating the sound emitter the relay 49 is energized by press button 50 over contacts 4, 5, 10 on the spindle of the sound emitter valve and locks up over contacts 48. When the relay is energized, contacts 51 short-circuit the condenser 20 to ensure its complete discharge and condenser 43 and neon lamp 41 are short-circuited at contacts 52. Upon operation of the sound emitter, the relay 49 is de-energized at the insulating segment 11, and the contacts 46, 53 close the charging circuit of the condenser 43 which after a time interval effects operation of the neon lamp 41 and permits current flow in the transformer primary 42 to develop a voltage additional to the battery 38 in the circuit of the neon lamp 26. This effects illumination of the lamp 26 and causes a constant current to flow in the circuit. The constant p.d. developed across the resistance R2 renders the grid of valve 21 positive and the condenser 20 is charged at a rate dependent upon the resistance R1. The delay of operation of the lamp 41 prevents inaccurate operation of the time measuring system by the direct reception of sound. Upon receipt of the echo, a voltage of reverse sign is introduced into the circuit through the transformer 27 and rectifier 29 to break down the lamp 26 and prevent further flow in the constant current circuit. In consequence, the p.d. across R2 becomes zero and the grid is rendered negative to prevent further charging of the condenser. A recording milliammeter may be employed in the plate circuit to produce a permanent record of the vertical profile of the ground traversed.