Patent GB-1208315-A (GB)
Title: Improvements in or relating to guidance systems
IPC: G05D1/00
Filed: 1967-12-15
Abstract: 1,208,315. Wave-energy direction finding. ALBISWERK ZURICH A.G. 15 Dec., 1967 [16 Dec., 1966], No. 56979/67. Heading H4D. In a guidance system for a craft, the craft carries a first direction-finder (D.F.) which scans conically about an axis lying along the direction of travel, a second D.F. which determines the direction of a spatial axis represented by a gyroscope by scanning conically about an axis of the craft, the two scanning motions being synchronized, a circuit for comparing in each scan the timing of the pulse produced by the first D.F. on detecting a body with a pulse produced by the second D.F. on detecting the position of the axis of the gyroscope, and control means in the circuit for producing a control signal when the same angular differences are found in successive scans, and a delay unit connected between the second D.F. and the circuit by the control signal until a further control signal from the control means indicates that substantially the same angular differences are obtained from successive scans with the delay unit in circuit and the delay unit is then switched out of circuit. The invention is applied to collision avoidance. In one embodiment, the first D.F., 01, is a radar with a conical scan angle α with respect to travel direction BA and the second D.F., 02, is an optical or infra-red device for determining the direction of travel by placing a radiator IR on one end of the shaft of a gyroscope K and determining the relative position of the radiator by a system including a rotating disc Sp containing a radial radiation-transparent slot and a detector D. The rotations of the radar aerial and of the disc are synchronized by unit Sy. The first pulse to arrive from a D.F. is stored until the arrival of a pulse from the other D.F.; the arrival interval measurement is stored until the measurement of the interval between the next pair of pulses; when two successive intervals are equal, a control pulse causes relay R1 to be energized and holds on via its make-contact r11 and a break-contact r22 on relay R2. Contacts r12, r13, r14 are operated by relay R1, contact r14 causing a delay device ZV is connected. A second control pulse causes relay R2 to be energized, thereby releasing relay R1 and disconnecting the delay device. When the arrival interval above is constant, the sighting line bearing is constant and a collision situation exists, but the insertion of the delay device produces a signal at terminal A for an automatic pilot to change the craft heading until the arrival interval again becomes constant but, this time, with falsified information, thereby avoiding possible collision. A visual or aural alarm may be provided, operative by relay R1, a pilot altering heading until the alarm ceases. Unit SU may consist of a bi-stable (B, Fig. 2, not shown) controlling a polarized relay (RR), a capacitor (C) and a Schmitt trigger (NJ) producing the control pulse for energizing relay R1. In an embodiment based on that described with reference to Fig. 5, several bodies are checked separately for possibility of collision, the radar output signals being gated and the gating being synchronized with the scanning, Fig. 3 (not shown); a radar display tube may be added. Specification 1,145,565 is referred to.