Patent GB-785230-A (GB)
Title: Improvements in or relating to electric analogue calculating instruments
Inventor: STARKS-FIELD ALFRED BENJAMIN
IPC: G01S7/295
Filed: 1955-02-16
Abstract: 785,230. Electric analogue calculating systems. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. Oct. 20, 1955 [Feb. 16, 1955], No. 4595/55. Class 37. An electric analogue calculating apparatus comprises at least three distinct wattmeter elements each comprising a mutually displaceable stator and rotor wherein the rotors are mechanically coupled together; means for applying at least one input current representing a corresponding parameter to a winding of one wattmeter element to develop a rotor torque proportional thereto, means for applying a second input current representing a second parameter to at least one winding of a second wattmeter element to develop a rotor torque proportional thereto, means for energizing one winding of the third wattmeter element with a constant amplitude A.C., and means developing a D.C. corresponding to the A.C. induced in the remaining winding of the third wattmeter element which is applied to a winding of one of the first two wattmeter elements to restore torque balance, at which it represents the product or quotient of the two input parameters, or the square or square root of a single such parameter, in accordance with the manner of connection of the stator and rotor coils. In Fig. 2, current 11 energizes rotor coil R1 of wattmeter element 1 (Fig. 1, not shown) while current 12 energizes the stator S1, and the resultant torque 11, 12 angularly displaces the rotors of ganged wattmeter elements 1, 2, 3 against a restoration spring (not shown). Stator S3 is A.C. energized and the alternating voltage induced in rotor R3 whose phase angle is dependent on the angular rotation produced by element 1 is amplified and applied to phase detector PD together with a reference voltage from the A.C. supply. The D.C. output after smoothing energizes stator S2 through meter M to develop a balancing torque in co-operation with rotor R2 energized by a constant value D.C., and at balance the meter M indicates a value proportional to the product of I1 I2 and of the input parameters represented thereby. Other utilization or response circuits may be connected to terminals T across the meter, while for squaring, the same current may energize both rotor R1 ans stator S1. For division (Fig. 3, not shown), current I1 energizes stator S1, I2 energizes stator S2, and the D.C. output of the phase detector energizes rotor R1 so that at balance the meter reading is proportional to I2 -. For determining a square root (Fig. 4, not I1 shown), current I1 energizes stator S2, a constant D.C. energizes rotor R2, and the A.C. output of rotor R3. proportional in amplitude to its angular rotation is amplified, rectified, and smoothed to a D.C. energizing rotor R1 in series with stator S and meter M. At balance, the value of current in the latter is proportional to #11. For determining the square root of the sum of two squares (Fig. 5), currents I1 and I2 representing the input parameters energize respectively rotor R1 in series with stator S1 and rotor R2 in series with stator S2, while stator S4 is energized from a constant A.C. source and the output of rotor R4 is amplified, rectified and smoothed to energize rotor R3 in series with stator S3 in series with meter M. Since the rotors are mechanically ganged, at torque balance the meter reading is proportional to#I1<SP>2</SP>+I2<SP>2</SP>.