GB1402711A - Radar tracking systems - Google Patents

Abstract

1402711 Monopulse radar ELLIOTT BROS (LONDON) Ltd 25 May 1972 [25 May 1971] 17037/71 Heading H4D In a ground-based amplitude on phase monopulse pulse-radar azimuth (AZ) and elevation (EL) tracking system comprising a diamond array of aerial feed elements A, B, C, D, Figs. 1 and 3, an indication of the target EL j which is unaffected by the presence of a target image signal due to reflections at the surface of the ground (or sea) is derived by a computer 23 (which also produces an output AZ error signal x) from a signal # representing the EL angle of the aerial boresight axis and three normalized signals D1/S, D2/S and N/S where S = A + B + C +D is the conventional sum signal which is applied to the difference channel phase-sensitive detectors 17, 18, and 19, D1=(A+B)-(C+D) and D2=(B+D)-(A+C), i.e. D1 and D2 would be the conventional EL and AZ error signals if the aerial array were rotated through 45 degrees to locate the elements A and B directly above the elements C and D; and N, the so-called "nonsense" channel signal is given by the difference between the sums of signals from diagonally opposite feed elements, i.e. N= (A+D)-(B+C), the amplitude and phase characteristics of the signal N in a plane perpendicular to the boresight axis being as shown in Fig. 3. As shown in the mathematical discussion in the Specification, it is more convenient to compute j<SP>2</SP>. In the absence of a target image signal, conventional AZ and EL error signals AZ(e) and EL(e) may be derived from the difference signals D1 and D2 in accordance with the equations AZ(e)=D1+D2, EL(e)=D1-D2.