Abstract: An active radar jamming system using a digital radio frequency memory (DRFM) as the central subsystem in the generation and detection of specific signal characteristics. Associated systems control the operation, data processing, and loading of the DRFM. Signals generated by the jamming system are either repeated replicas of the received radar signal stored in the DRFM, or newly generated signals constructed from data loaded into the DRFM by the associated subsystems. Such associated subsystems generate appropriate data for providing carrier and noise RF signals. Systems are also provided for determining the presence of phase coding and chirp modulation in the received radar signal data contained in the DRFM, and for detecting the angle-of-arrival of the radar signal.

Abstract: A device for imparting a selected delay to a pulse emanating from a transmitter before the pulse is returned as a simulated radar echo to a radar altimeter receiver. The selected delay is obtained by recirculating the transmitted pulse through a fixed delay element a prescribed number of times. The system includes a control circuit, including a single-pole, double-throw electronic switch coupled to a presettable counter which may be preloaded with a count value corresponding to the number of iterations of the transmitted pulse through a closed loop including the delay elements. Upon each such traversal, the counter is decremented and when the counter generates a borrow signal, the electronic switch diverts the pulse to the altimeter's receiver. The recirculation loop also includes pulse amplifying and shaping circuitry for compensating for attenuation and distortion of the recirculating pulse.

Abstract: An antenna system for a flying body for jamming radio/radar signal transmitting and receiving devices. The antenna system includes a receiver with a frequency discriminator, a transmitter with a variable frequency oscillator, a transmit/receive device for conducting signals to the receiver and for conducting the transmitter signal to the antennas, a switch for selectively or cyclically connecting the antennas to the receiver and transmitter, a time which enables the receiver device to receive signals from antennas during one complete cycle of the switch and which enables the transmitter during the subsequent transmit mode to furnish transmitter signals to selected antennas for at least one complete cycle of the switch and a memory in which frequency representations are stored so that each representation corresponds to a particular antenna via which signals were received.

Abstract: The isolation of mainbeam and sidelobe jamming signals from the desired signal being relayed by microwave communication links is accomplished by an antijamming antenna comprising a flat radome, a curved reflector and a transmit dipole. Positioned adjacent the dipole is a monopulse feed and comparator for main-beam jammers (dual-plane monopulse, multi-mode multilayer feed). Also forming part of the integrated antenna are auxiliary units for near-sidelobe and far-sidelobe jammers. An alternative embodiment includes a Cassegrain grating sub-reflector. Since the direction of the desired incoming signal in microwave communication links is precisely known, the antijamming antenna uses azimuth and elevation monopulse to make a spatial distinction between the desired incoming signal and the jamming signals.

Abstract: An N-point Fourier transform circuit for a moving target indicator system including a delay circuit with 2N-2 delays, N frequency filters, a processor for forming a main signal and N-1 auxiliary signals via time sample manipulation, a Gram-Schmidt adaptive canceller circuit for decorrelating the N-1 auxiliary signals from the main signal, and a first and second commutating switches. The first switch tracks a given set of N time samples through the delay circuit. The second switch switches the given set of N time samples through a different successive frequency filters of the N frequency filters every transmission. The first switch tracks in synchronism with the second switch and switches to obtain a new given set of N time samples every NT seconds.