Patent GB-846073-A (GB)
Title: Radio navigation system
IPC: G01S5/10
Filed: 1959-02-06
Abstract: 846,073. Radio navigation. STANDARD TELEPHONES & CABLES Ltd. Feb. 6, 1959 [Feb. 12, 1958], No. 4257/59. Class 40(7). [Also in Group XXXVI] A radio navigation system comprises three spaced beacons M, S 1 , S 2 , Fig. 1, defining a hyperbolic co-ordinate system and a mobile station P with a computer controlling indicators giving its cartesian co-ordinates X p , Y p  with respect to a given fixed point O, the computer including means for producing two adjustable cartesian voltages corresponding to the mobile station position, three quadratic equation solvers corresponding to the three beacon stations, each solver producing an output voltage corresponding to the difference # between the distances of the mobile station and the fixed point from the corresponding beacon such that # satisfies the quadratic equation connecting #, the distance and bearing of the fixed point from the corresponding beacon and the adjustable cartesian voltages, and means for applying the three solver voltage outputs together with voltages, partly derived from the mobile station receiver and determined by the distances of the mobile station and of the fixed point from each of the three beacons, to adjust the cartesian voltages so that the three quadratic equations corresponding to the three beacons are simultaneously satisfied. D M , D 1 , D 2  and #M, # 1 , # 2  are the distances and bearings of cartesian origin O from respective Loran transmitters M, S 1 , S 2 , #D M , #D 1 , #D 2  are the differences between the distances of mobile receiver P andorigin 0 from the transmitters; it is demonstrated that and similarly for #D 1  and #D 2  and these equations, are solved for #D M  &c. in units 48, 46, 47 respectively, Fig. 3A Values #D M  - #D 1  and AD M  - #D 2  are fed to summing: networks 55, 56 respectively into which are added their negative counterparts α p - α 0 , and # p  - # 0  from potentiometers 22, 23, Fig. 3, controlled by outputs: from Loran receiver 8 and quantities set in from manual; board 3. If the values of Xp, Yp, derived from servo-operatedpotentiometer wipers- 62, 66 respectively are the actual coordinates of the mobile station the outputs of the summing networks, are zero. Thus servos 60, 61 rotate to adjust the potentiometer outputs so that they represent the mobile's cartesian, co-ordinates and the latter are shown on indicators 13, 14. The servos also drive potentiometer wipers 63, 67 to afford an output Xp<SP>2</SP> + Yp<SP>2</SP> from amplifier 52 for application to each of the quadratic equation solvers. Switches 36-41 are set manually to enter the correct signs of factors Xp cos #, Yp sin #. Hand-operated' coupling 54 positions switches 53 and 59 according to which set of Loran hyperbolae run more parallel to north. Switch 70 controls reversal of the servos and is thrown if the indicated Xp, Y, values are unstable or change more than. estimated from the receiver's motion. Solving quadratic equations, Fig. 4. In a selfbalancing arrangement for solving a quadratic equation of the above form #D is generated by potentiometer wiper 83 driven by servos 82. -#D<SP>2</SP> at the wiper of ganged potentiometer 86 is added in network 92 to Xp<SP>2</SP> + Yp<SP>2</SP> from line 52a and term - (Xp<SP>2</SP> + Yp<SP>2</SP> - #D<SP>2</SP>)/2D is produced by shaft 49 rotation representing 1/2D from the manual board. This term is added to X p  cos # + Y D  sin # and to #D in network 78 and amplifier 81 energizes the servo to adjust potentiometers 85, 86 to give the value of #D necessary to reduce network 78 output to zero. Postitive and negative values are available on lines 96, 97 respectively; the former are used from solvers 46, 47, Fig. 3A, and the latter from solver 48.