Patent GB-412267-A (GB)
Title: Improvements in apparatus for locating sound sources, particularly travelling aircraft
IPC: G01S1/72
Filed: 1932-12-23
Abstract: 412,267. Locating sounds. HILLIER, A., c/o Sperry Gyroscope Co., Great West Road, Brentford, Middlesex.-(Sperry Gyroscope Co., Inc. ; Manhattan Bridge Plaza, Brooklyn, New York, U.S.A.) Dec. 23, 1932, No. 36489. [Class 118 (ii).] A sound locator for locating the position of aircraft is coupled with a cam actuated mechanism which compensates for the speed of the aircraft and the velocity and direction of the wind to determine the actual position of the aircraft so that a searchlight, coupled to the locator, can be set to direct a beam of light onto the aircraft. As shown in Fig. 1 an aircraft flying in the direction BD against a wind is located at A by the sound locator L. Owing to the wind, the apparent position of the aircraft might be B while the aircraft has moved to C during the period taken by the sound to reach L. Apparatus at L determines the position C and also the direction SC in which the searchlight S must be turned to throw a beam of light onto the machine. The readings of L are transmitted to set pointers on apparatus G where hand-operated " follow the pointer " mechanism transmits controls to set S in the appropriate direction. Subsidiary hand controls are provided on the searchlight to enable the beam to locate the aircraft after the approximate setting has been completed from <G.> Correcting mechanism. The correcting mechanism is shown diagrammatically in Fig. 3 and a face view is indicated in Fig. 9. The azimuth shaft 8 of the locator L (Fig. 2) drives, through gearing 40, the shaft 36, the pointer 50 indicating on dial 14 the actual direction of the locator. Similarly the elevation is indicated on dial 35, the pointer 351 being driven from shaft 2. Loose on the shaft 36 are two sleeves 37, 38 which carry dials 29 and 28 respectively. These dials are set by knob 48 (which effects different controls in each of its four positions) to the wind deviation angle and the angle between LS (Fig. 1) and the North respectively. The cam 43, mounted on sleeve 38, is cut to put into the apparatus the sine of the angle BLS, Fig. 1 whilst the cam 45 mounted on sleeve 37 introduces the sine of the angle between the wind direction and the target bearing line. Cam 44 applies a correction for the elevation angle and is driven from shaft 2, whilst shaft S<11> adds the slant range factor. The lever 87 is thus set to a position determined by these corrections and controls the dial 20 to show the combined wind and parallax azimuth correction. The wind velocity is set by hand on dials 15, 16, 17 relating to ground, altitude and mean velocities respectively whilst the estimated altitude of the aircraft is set on dial 12 and flexible bellows 22, 23 controlled from the reversible pumps 9, 8<1>, set dials 18, 19 according to a function of the angular travel of the sound locator combined with a function of the slant range. The fluid pressure apparatus is similar to that described in Specification 410,239. The dials 19, 20 are placed side by side so that the correction for wind parallax and sound lag is read with respect to an index 19<1> (Fig. 9). Similarly adjacent to dial 18 is a dial 21 set by knob 21<1> for introducing the known error in elevation. Setting searchlight. The handle 10 (Figs. 2 and 9) is now turned to set coarse and fine dials 31, 31<1> to read the same as 19, 20 and this total correction is algebraically added, through differential 41, to the azimuth angle of the sound locator, the final corrected angle being transmitted to sender 6<1>. Similarly the elevation correction indicated on dials 18, 21 is set by handle 11, on dials 32, 32<1> and is algebraically added to the actual elevation by differential 42 and the result is transmitted to sender 7. A third differential 30 (Fig. 3) compensates for an elevation error due to mounting of the sound locator gears. The final readings are transmitted to the instrument G, Fig. 2, and set pointers 116, 117 to the azimuth and elevation readings and further pointers 118, 119 are made to follow 116, 117 by handles 141, 141<1>. As pointers 118, 119 are moved, control currents are sent to the searchlight S to set the lamp in the required direction. A further mechanism in which elevation errors due to wind and parallax are computed is also described.