Patent GB-1127053-A (GB)
Title: A method and system for locating a vehicle with reference to a predetermined position
IPC: G01S5/10
Filed: 1966-03-11
Abstract: 1,127,053. Radio navigation. SOC. D'ETUDES RECHERCHES & CONSTRUCTIONS ELECTRONIQUES (SERCEL). 11 March, 1966 [12 March, 1965], No. 10938/66. Heading H4D. The invention relates to the determination of the difference in the positions of a vehicle and a predetermined point, and the expression of said difference in orthogonal coordinates X and Y, using phase measurements of received radio transmissions to define said positions. Fig. 1 shows two sets of intersecting isochrones (A 1 -A 3 ) and (B 1 -B 3 ) produced in any known (e.g. hyperbolic system) manner, and defining the predetermined position (A) as the intersection of isochrones (A 2 ) and (B 2 ) representing respective differential phases of # 2  and # 1 , and the position of the vehicle as the intersection if isochrones (A 1 ) and (B 3 ) representing respective differential phases of #<SP>1</SP> 2  and #<SP>1</SP> 1  # 2  and 91 are known, and #<SP>1</SP> 2  and #<SP>1</SP> 1  are determined by phase measurement. #<SP>1</SP> 2  and #<SP>1</SP> 1  are represented by the angular rotation of respective motors 2 and 1, Fig. 2. Via telemetary means 4 and 3 these rotations are converted to like rotations of the rotor shafts of possibly distant motors 6 and 5. The stators of these motors are angularly positioned by amounts respectively representing # 2  and # 1 , such that the outputs of the rotors have respect phase angles representing ## 2  = # 2  - #<SP>1</SP> 2  and ## 1  = # 1  - #<SP>1</SP> 1 . The phase angles are converted into voltage values by converters 8 and 7. ## 2  represents the distance between isochrones A, and A 2  and ## 1  represents the distance between isochrones B 2  and B 3 . Thus X = a## 1 +b## 2 , Y = c## 1 + d## 2 , where a, b, c, d are constants. Such computations are carried out by calculator 9 to give an output representing X which is fed to a motor 10 and an output representing Y which is fed to a motor 13. Motor 10 controls the vertical position of a wire 11 and motor 13 controls the horizontal position of a wire 14, orthogonal to wire 11. The centre of a rectangular chart table 12 is made the predetermined point, and the crossover position of the wires 11 and 14 represents the vehicle's actual position. X and Y are selected to represent the S-N and E-W positions of the vehicle. The wires 11 and 14 may be replaced by slotted guides moving underneath a ground glass chart and carrying a light spot projector at the intersection of the slots. To convert X and Y into axes fixed with respect to the vehicle, e.g. fore/ aft and athwartships in the case of a ship, the outputs of calculator 9 are fed to a second calculator 15 fed with the heading of the vehicle. The outputs of calculator 15 may control motors 10 and 15 instead of the outputs of calculator 9. A second ground glass chart marked with vehicle axes may be positioned to rotate coaxially with chart 12 under the heading control of the ship. Calculator 15 may change X and Y into polar co-ordinates, or may control the position of the vehicle to bring it to the predetermined position. The vehicle axes marked chart may be fixed and the N-S, E-W marked chart rotated. A navigation system providing the radio transmissions, may comprise two transmitters, one at a known stationary point, and the other on the vehicle, and two receivers at known stationary points. The receivers each measure the difference in the phases of the signals from the two transmitters and said measurements are telemetered to the vehicle for use as described.