Determining system for angular position of spinning projectile - uses low frequency carrier wave horizontally polarised w.r.t. each surface independently on transmitting aerial orientation

摘要

The trajectory of a spinning projectile (1) is tracked by radar (4) located on a ship and its course is corrected by firing gas discharge units (6) to reach a target (2) tracked by a second radar (3). To ensure that the gas discharge units are fired at the instant when the spinning projectile assumes the correct position, transmitter (8) sends the information about the desired projectile angular spin position 'phi g' calculated by a computer (5). To enable the projectile to determine its instantaneous angular position w.r.t. the earth surface, transmitter (7) with its associated vertical antenna transmits a low frequency carrier wave whose electric field component is vertically polarised and the magnetic field component is horizontally polarised w.r.t. the earth surface. This polarisation is independent of the antenna orientation. A comparator (12) on the projectile compares the instantaneous angular position from the signal received by system (13) with the value 'phi g' received from the ship by the receiver (9) and activates the gas discharge unit at the moment when both values are equal.