GB1427164A - Interference eliminating system for radars - Google Patents

Abstract

1427164 Pulse radar NIPPON ELECTRIC CO Ltd 19 Feb 1973 [19 Feb 1972] 8065/73 Heading H4D In a pulse radar producing wanted echo pulses d, Fig. 5, line 22, interference pulses e from an adjacent radar are suppressed by ranging the time intervals between successive transmitted pulses through a predetermined cycle of at least three different time intervals T1, T2, T3, Fig. 5, line 21, and applying the output from the radar receiver 13, Fig. 6, in parallel to: (1) three AND circuits 40, 42, 44 coupled to corresponding AND gates 41, 43, 45 which are respectively enabled during time intervals T3, T1, T2 by the outputs 30, 28, 29, Fig. 5, from a control signal generator 15; and (2) three delay channels 17, 18, 19 each comprising an input AND gate coupled to two series connected first and second delay circuits whose outputs are coupled as shown to the AND circuits 40, 42, 44 such that in the nth delay channel (n = 1, 2 or 3) the input AND gate is enabled during time internal Tn by the generator 15 and the delay periods of the first and second delay circuits are Tn and T(n + 1) respectively. Thus during time interval T3 the signals applied to AND circuit 40 are as shown at 23, Fig. 5, from which it is seen that only the wanted pulses dl, d2 and d3 coincide to produce a resultant output pulse; a corresponding process occurs during the other time intervals T1 and T2, the resultant combined outputs from the three AND gates 41, 43, 45 being shown at Fig. 5, line 24. If an adjacent radar operates with the same time intervals but in a different sequence, e.g. T1, T3, T2, Fig. 5, line 25, mutual interference between the two radars is prevented.