Patent GB-1432933-A (GB)
Title: Guidance and control system for target-seeking devices
IPC: F41G7/22
Filed: 1957-02-20
Abstract: 1432933 Missile guidance HUGHES AIRCRAFT CO 20 Feb 1957 5824/57 Heading H4D In a self-propelled missile having jaw and pitch control surfaces 50, 52 and 36, 38, the missile is steered on a proportional navigation course to a target from which radiant energy may be received. The system comprises a rotating parabolic reflector 20 for scanning a conical field in which the target is located and receiving the target radiations, the reflector being mounted as a free gyroscope, its rotational axis constituting one of the three axes of freedom. As shown in Fig. 1 the radiant energy is constituted by high frequency radio echo signals resulting from illumination of the target by a transmitter situated at the launching station. The echo signals received by the antenna 22 on the reflector scan axis are amplitudemodulated by an amount dependent upon the displacement of the target from the axis and are fed to a receiver 25 where they are mixed with the output of a local oscillator to produce i-f signals which are fed to an error detecting channel 28. To prevent interference with the system from extraneous signals the i-f signals are gated by a circuit (Fig. 6, not shown) developing signals in synchronism with the received echo signals. Reference signals 72<SP>1</SP>, 73<SP>1</SP>, 74<SP>1</SP>, 75<SP>1</SP> are generated by rotation of the reflector 20 by a magnet 78 moving past coils 72 ... 75 (Figs. 5, 7) these signals also being fed to the channel 28. The coils 72, 74 and 73, 75 form two groups, each group acting on a respective one of a pair of switching circuits in the channel 28 (Fig. 6, not shown) both switching circuits being supplied with the output of the receiver 25 and each switching circuit controlling, respectively, the surfaces 50, 52 and 36, 38 through amplifiers 42, 30 and actuators 48, 34 to steer the missile on the proportional navigation course. Fig. 7 shows a typical sine wave due to an amplitude-modulated echo signal received from a target T displaced at a position x from the line of sight between the missile and target. The outputs of the' switching circuits are dependent upon the values of the sine wave at the instant when the reference pulses 72<SP>1</SP> ... 751 are generated and hence in the example shown a maximum output is derived from the switching circuit connected to coils 72, 74 and zero output is derived from the circuit connected to coils 73, 75. The outputs of the switch circuits are also fed to torque motors 24, 26 for precessing the reflector 20 to maintain the target on the scan axis. Damping to prevent oscillations in pitch and yaw may be provided by rate gyro control units 40, 46 coupled to summing amplifiers 32, 44, and rolling of the missile may be limited by a rate gyro control unit 54. In a modification, the output of the amplifiers 30, 42 supplies directly only the torque motors 24, 26, and the torque motors in turn apply steering signals to the amplifiers 32, 44. In a simplified system discribed with reference to Fig. 11 (not shown) the reflector 20 receives infra-red radiations from the target which are converted into electrical signals and no transmitter to illuminate the target is required.