Patent GB-867657-A (GB)
Title: Improvements in or relating to interception control computers
Inventor: ATKINSON ERIC HESLINGTON
IPC: F41G9/00
Filed: 1958-12-29
Abstract: 867,657. Electric analogue calculating. DECCA RECORD CO. Ltd. Dec. 29, 1959 [Dec. 29, 1958], No, 41943/58. Class 37. An interception control computer comprises a first electric generator for signals representing target velocity components V T  sin # and' V T  COS # where V T  is target velocity and # is the angular direction of the target track, a second electric generator incorporating a first resolver with adjustable angular input for signals representing interceptor velocity components V I  sin # and V I  cos # where V I  is interceptor velocity and # is the first resolver angular setting, a first summation circuit coupled to the first and second generators to derive output signals representing V T  sin # + V I  sin #, a similar summation circuit deriving output signals representing V T  cos # + V I  cos #, second and third ganged resolvers with adjustable angular inputs coupled to first and second summation circuits to derive output signals representing [V I  sin # + V I  sin #] cos α and [V I  cos # + V I  cos #] sin α where α is the present bearing of the target from the interceptor, and a servo system responsive to the difference between the outputs of the second and third resolvers to adjust the angular setting of the first resolver to reduce the difference to zero, at which # represents the required course for target interception when the second resolver is set to an angular input for α. A D.C. energized sine-cosine potentiometer, 10 having an earthed centre point 12 has two right-angled arms rotated in accordance with # to energize ganged linear potentiometers 17, 18 adjustable in accordance with V T  to derive outputs representing V T  sin #, V T  COS # and a further similar D.C. energized sine-cosine potentiometer 21 adjusted in accordance with # to energize ganged linear potentiometers 25, 26 adjustable in accordance with V I  to derive outputs representing V I  sin # and V I  cos #. The respective sine and cosine components are summed over resistance input amplifiers 31, 36 and the outputs of these are reversed in amplifiers 43, 49 so that the ends of single arm ganged cosine and sine potentiometers 41, 47 centre-tapped to earth are respectively energized in opposite polarities, the potentiometers being manually or automatically adjusted to a. The outputs of the potentiometers energize opposite ends of a centre-stable polarized relay A whose contacts A 1  control over relays B, C and contacts B 1 , C 1  the sense of rotation of servomotor 57 linked to adjust potentiometer 21 to the required value of intercepter course for target interception, at which equation is satisfied, and the inputs to relay A are equalized. Hunting is reduced by resistance 60 in series with relay A shunted by normally closed contacts D 1  which open when relay D across motor 57 is energized to reduce the sensitivity of relay A until balance is approached, at which relay D releases so that the balance point is reached in a series of steps of duration determined by the relay time constants. Alternatively, a resistor may. be connected in series with the motor 57 and a non-polarized relay of lower sensitivity is connected in series with relay A to short-circuit the resistance on energization so that the motor runs at low speed for small errors and high speeds for large errors. The required intercepter course may be computed for the attainment of a predetermined position relatively to the target for weapon attack by feeding in corrected target information derived from the apparatus described in Specification 867,367. The target and intercepter velocity and bearing information maybe derived from a radar, and the present intercepter to target bearing α may be determined by superimposing a marker trace on the radar display indicating intercepter and target positions, which may be adjusted to intersect both positions by signals from potentiometer 65 ganged to potentiometers 41, 47 which control the rates of scan of two waveform generators energizing orthogonal cathode-ray deflector coils. The required bearing may be indicated on a dial or transmitted to a distant point.