Pulsed doppler radar system with small intermediate frequency filters

Abstract

A process and a system for selecting a pulse repetition frequency that causes clutter pulse repetition frequency lines from the negative carrier frequency and from the clutter harmonic frequencies to lay on top of clutter pulse repetition frequency lines from the positive carrier frequency. A pulsed Doppler radar receiver of the system has one or more channels each comprising of a radio frequency input section for receiving a radio frequency carrier. Following the radio frequency input section are one or more serially arranged intermediate frequency sections that terminate in a last intermediate frequency section. The last intermediate frequency section is followed by analog-to-digital conversion and down-conversion to baseband in-phase and quadrature channels. In-phase and quadrature data from the in-phase and quadrature channels is processible by a computational system to detect and track a target in the presence of clutter. A pulse repetition frequency space is determined that consists of all pulse repetition frequencies equal to one or two times the intermediate frequency of the last intermediate frequency section divided by an integer. The computational system is then directed to choose a pulse repetition frequency from the pulse repetition frequency space to use in tracking the target. The system may be in a guided missile or other flying object.