Radar system

1,119,040. Pulse radar. MULLARD Ltd. 13 March, 1967, No. 11660/67. Heading H4D. In a radar the transmitter SDM (e.g. a spinning disc magnetron) produces a cycle of N spaced pulses P 1 . . . P N at least most of which are on different carrier frequencies F 1 ... F N , the receiver has N channels LMa . . . tuned to the corresponding transmitted carrier frequencies, the channel outputs are delayed by lines DLa ... such that echoes from the same stationary target are brought into time coincidence at the input of adder ADD, and the sum signal is timed relative to the transmissions: according to the invention the receiver channel tuning means comprises a frequency measurer FMU responsive to the frequency of each transmitted pulse to tune such channels in cyclic succession. The inter-pulse spacings may be irregular but in the embodiment they are each equal, #T, the lines DLa, DLb ... introduce respective delays of 9#T, 8#T... and device UD is a type A display with its time-base triggered once every 10#T. Enhancement of wanted targets in clutter is achieved, Fig. 2 (not shown). The tuning of the receiver channels may incorporate a store ST connected to frequency measurer FMU; the tuning of a channel is maintained until a time N.#T later. Certain elements may be arranged on a printed-circuit board, Fig. 4 (not shown).