Method of producing velocity-aided range gates

Claim 1

In the operation of a guidance system for a guided missile in flight, such missile carrying the combination of a pulse Doppler radar and a digital computer to derive digital signals representative of the position of a selected target relative to such missile during an intercept and representative of the then existing Doppler velocity between such missile and target, the method of generating a range gate compensated for Doppler velocity, such method comprising the steps of: (a) firstly, periodically recording the then existing digital signals out of the digital computer to provide corresponding digital signals extant in each interval between recording, each such interval being greater than the pulse repetition interval of the pulse Doppler radar; (b) secondly, transferring the extant digital signals indicative of the position of the selected target to a random access memory and the extant digital signals indicative of the Doppler velocity to a counter; (c) addressing the random access memory and actuating the counter at different rates to produce a velocity-aided range gate control signal, the time of occurrence of such control signal after each transmitted pulse being varied in accordance with extant digital signals indicative of Doppler velocity; and (d) synchronizing the velocity-aided range gate control signal with each pulse transmitted by the pulse Doppler radar.