GB1475414A - Direction finder - Google Patents

Abstract

1475414 Radio direction-finders LICENTIA PATENT-VERWALTUNGS GmbH 5 June 1974 [6 June 1973] 24895/74 Heading H4D In an arrangement for automatically finding the directions of incidence of a plurality of waves having different carrier frequencies within a predetermined band an antennae system provides directionally dependent output voltages, a sampling device provides instantaneous values of the voltages at predetermined successive intervals, and a computer which is arranged to receive the instantaneous values is programmed to determine therefrom the directions of incidence of the waves. The invention is described in terms of two waves received by an Adcock direction-finding antennae system but is treated as being of general application where voltages are produced which are phase and amplitude dependent on the wave directions. An appropriate number of samples is required for more than two waves. As described, an Adcock aerial system 1 is connected to a three-channel Watson-Watt type amplifier 5 which provides output voltages respectively proportional to the amplitude of an incident wave, to the amplitude multiplied by the sine of the azimuthal angle of incidence, and to the amplitude multiplied by the cosine of said angle. With two waves incident upon the aerial system, the voltage relationships are: where z, y, x are the voltages at time t in the channels 2, 3, 4, A 1 , A 2 are proportional to the amplitudes of the two waves, # 1 , # 2 are their angular frequencies, # 1 , # 2 , their phases, and α 1 , α 2 their angles of incidence. It is demonstrated mathematically in the Specification that if the instantaneous values of z, y, x are determined at times t=0 and t=t 0 , then the values of α 1 , α 2 may be calculated. The time scanning is effected by a device 6, which is controlled over a line 9 by a computer 8. A sequence of pulses is obtained, which are digitized in an analogue/ digital converter 7 and fed to the computer. A conventional display device may be paralleled across the outputs of the amplifier 5.