Abstract: A radar system and technique provide the capability to detect a target of interest and maintain the detection in the presence of multiple mainlobe and sidelobe jamming interference. The system and technique utilize digital beamforming to form sub-arrays for canceling jamming interference. Jamming is adaptively suppressed in the sub-arrays prior to using conventional deterministic methods to form the sum, &Sgr;, and difference, &Dgr;, beams for monopulse processing. The system and technique provide the ability to detect a target of interest, provide an undistorted monopulse ratio, m, and maintain target angle estimation, in the presence of multiple mainlobe and multiple sidelobe jammers.

Abstract: Generating a secondary beam (11) slightly offset from the main data collection beam (9) and obtaining hot clutter reference to be used in a conventional side lobe jammer processing algorithm (31). Advantage is taken of the typical geometries of a standoff jammer (1) which provides nearly matched dispersion characteristics of the jammer RF when viewed with the two received beams. The important parameter is dispersion relative to the received bandwidth. The secondary beam, which may be identical copy of the main beam except for target information, is placed offset by approximately two beam widths toward the jammer. The offset distance is chosen so that there is minimal and preferably no overlap in the main beam footprint on the ground but is as close as possible thereto. If there is overlap, then there is a chance that the target will appear in both beams and therefore be suppressed.

Abstract: The present invention describes a system for counteracting countermeasures against radar detection. Two known countermeasures are “phase front tilting” and “isotropic scattering.” The invention accomplishes this counteraction by deliberately producing a tilt in the phase front of the transmitted energy. This causes the phase front tilting countermeasure itself to become a tracking signal source for the radar system. The isotropic scatterer types of countermeasures are insensitive to the phase front of the transmitted energy and hence produce return signals which may be distinguished from a true radar echo return signal which is highly sensitive to the phase front of the transmitted energy. Thus this invention provides a radar system having a high degree of immunity to radar countermeasure devices.

Abstract: A radar system receiver having an antenna system adapted to receive a jammer signal from both a direct path and from an indirect path. The direct and indirect paths have both differential Doppler frequency and differential time delay induced phase shifts. The antenna system includes a plurality of antenna elements. A plurality of radar receiver sections, each one having a clutter filter, is provided. Each one of the receiver sections is fed by a corresponding one of the antenna elements. An adaptive jammer canceler is fed by the plurality of radar receiver sections for providing a beam forming network to suppress both the direct and indirect paths of the jamming signal.

Abstract: An apparatus and method for inserting a waypoint into a preexisting flight plan which includes selecting a waypoint on a graphical display of a portion of the flight plan and automatically generating a proposed changed flight plan based upon inserting the waypoint into the nearest leg of the flight plan.

Abstract: In a radar system, sampled aperture data are received from an antenna array. The sampled aperture data include data that do not correspond to echo returns from a beam transmitted by the antenna. A covariance matrix is generating using the sampled aperture data. An eigenvalue decomposition is performed on the covariance matrix. A direction of arrival is determined from which at least one jammer is transmitting a signal included in the sampled aperture data, based on the eigenvalue decomposition.

Abstract: In a radar system, sampled aperture data are received from an antenna array. The sampled aperture data include data that do not correspond to echo returns from a beam transmitted by the antenna. A covariance matrix is generating using the sampled aperture data. An eigenvalue decomposition is performed on the covariance matrix. A direction of arrival is determined from which at least one jammer is transmitting a signal included in the sampled aperture data, based on the eigenvalue decomposition.

Abstract: A radar system including a blanker and a sidelobe canceler is described including an open loop nulling circuit for introducing one or more nulls in the main beam and a blanker beam. With this arrangement, the blanker can be operated even in the presence of strong sidelobe jamming without the conventional problems attributable to noise amplification. Also described is an antenna configuration for implementing the open loop nulling, including a pair of orthogonal linear arrays. One of the arrays is omnidirectional in azimuth and directional in elevation and the other array is omnidirectional in elevation and directional in azimuth in order to point the main and blanker beams in the direction of jammers. In one embodiment, the radar system further includes a spoofer and the crossed linear arrays process the spoofer signals on transmit and process blanker signals on receive.

Abstract: A wideband adaptive digital beamforming technique for maintaining a high range resolution profile of a target in motion in the presence of jamming utilizes a sequence of adaptively calculated narrowband jamming cancellation weights. The adaptive weights are calculated such that the desired frequency dependent gain is maintained toward the target center. These adaptive weights tend to preserve the range profile quality and low range sidelobes. This technique also tends to eliminate signal cancellation problems as well as adaptive weight modulation effects.

Abstract: A wideband adaptive digital beamforming technique for maintaining a high range resolution profile of a target in motion in the presence of jamming utilizes a sequence of adaptively calculated narrowband jamming cancellation weights. The adaptive weights are calculated such that the desired frequency dependent gain is maintained toward the target center. These adaptive weights tend to preserve the range profile quality and low range sidelobes. This technique also tends to eliminate signal cancellation problems as well as adaptive weight modulation effects.

Abstract: A signal processing circuit is disclosed for providing fuze-on-jam capability in a target detecting device, while in the presence of continuous wave or continuous wave noise jammer signals. A target detection system will protect the target detecting device from noise jammers and continuous wave radars or continuous wave jammers by providing a circuit which samples the negative or positive bias produced by the noise modulated CW signal and produces either positive or negative polarity as seen by the antenna. If negative pulses are produced, they will actuate the target detecting gate and guard circuit and after the missile has passed the critical angle of the antenna the phase change will then produce firing in the normal manner. The sampled output is fed into the target detecting mixing circuit and no interference with normal operations of the target detecting device occurs while a fuze-on-jam or CW capability is provided.

Abstract: In an adaptive antenna device having directivity pattern generators operable in accordance with different algorithms, respectively, in a baseband modem, beam steering processing, null steering processing, and estimating processing of an arrival direction are executed in parallel to one another. Parameters resulting from the beam and the null steering processing are controlled by processing results of the estimating processing and are weighted and combined to individually generate directivity patterns based on the different algorithms.

Abstract: Electronic Warfare (EW) systems aboard aircrafts are used to protect them from guided missile by denying threat radar systems the ability to track the aircrafts. In a typical operation, a threat radar system transmits RF signals aimed at the target aircraft. The surface of the target reflects a portion of the incident signal back towards the threat radar antenna where the reflected signal is detected, allowing the threat radar system to determine the target's range, angle and velocity. The present invention relates to EW systems that are dependent on measuring the RF phase of a signal transmitted by a target tracking threat radar. The use of the invented technique will make it possible to implement a robust Electronic Counter-Measures (ECM) technique, known as Cross-Eye, using two airborne platforms. The technique is very effective in preventing a threat radar from tracking a target aircraft and guiding a launched missile to the target aircraft.

Abstract: A tracking radar receiver as described herein is relatively invulnerable to image frequency jamming. Partial image-rejection down-converters down-convert RF signals to IF signals in each of various sum and difference receiver channels. Image frequency components of the IF signals exhibit a predetermined amplitude and phase relationship relative to corresponding real frequency components for each of the channels. Thus, phase and amplitude tracking between the various channels is achieved even when image frequency signals are received.

Abstract: A method and system for using the main diagonal elements of the Cholesky factor of the spatial covariance matrix to estimate the number of jammers present, by evaluating the AIC (or other) test function using the Cholesky diagonal elements in place of covariance eigenvalues. The Cholesky factor is often available as a by-product of adaptive beamforming.

Abstract: The present invention relates to a method for the protection of mobile military facilities, in particular military bridges, against target-seeking guided weapons equipped with various threat sensors, wherein the mobile military facilities are equipped with active and passive anti-sensors for detecting a threat by approaching target-seeking guided weapons and computing their trajectories and determining suitable intercept coordinates for deploying countermeasures. Moreover a mobile dirigible launcher furnished with various decoy effective agent ammunitions is provided in the surroundings of the facility to be protected and/or immediately on the said facility.

Abstract: The invention relates to a method of locating a jammer (14) of a satellite telecommunications system (10). To locate the jammer, at least two of the following three measurements are performed: a measurement of the difference between the instant of arrival at the telecommunications satellite and at a detection satellite (16) of signals transmitted at the same time by the jammer (14), the detection satellite being used solely for detection purposes; a measurement of the difference between the frequencies received by the telecommunications satellite and by the detection satellite, for a signal transmitted by the jammer; and an interferometric measurement of the angle between a direction associated with the detection satellite and the straight line between said satellite and the jammer (14).

Abstract: A radar system (10) which transmits a random noise signal. The transmitted signal is embodied as an electromagnetic signal and is directed at an object or target. The object or target reflects at least a portion of the electromagnetic signal which is returned to the radar system. An image of the electromagnetic random noise signal is stored in memory (16) and compared with the returned modulated signal. Based on the correlation value, a determination is made regarding the object or target. In a particular implementation, the radar system is used in a target detection device (TDD) (10) in order to determine the distance from the target or object to the device and the relative velocity of the target or object and the device. When the target or object reaches a predetermined distance and also satisfies any other system requirements, the TDD (10) initiates a detonation signal which causes detonation of the missile or warhead.

Abstract: A radar system includes a null processor coupled to transmit receive modules. The null processor inserts nulls in the sum pattern at locations for suppressing a jamming source. The null processor determines the difference pattern based upon the product: sum*sin(x), where sum is the sum pattern and x is the azimuth angle.

Abstract: In a jamming cancellation system wherein a balanced modulator receives as two inputs thereto: the desired plus jamming signals, and the AM difference frequency produced by the beating of the desired and jamming signals, jamming suppression, in an environment containing two jamming signals, is achieved by peak detecting the output from the AM difference frequency producing means and applying same directly to the receiver video input or upconverting same to the receiver r.f. frequency and applying same to the system receiver.

Abstract: A coded phase modulation communications system which relates to communications systems in which undesired detectability of the radiated signal is materially reduced, and wherein the vulnerability of the system to interfering signals, such as, intentional jamming signals, is substantially reduced. In the system, a radio frequency communications signal is phase modulated by a random or random appearing, but repeatable pattern of noise signal. The received signal is modulated by an identical noise signal, which when synchronized with the original noise modulation results in erasing the noise, and thereby recreating the original, continuous, communications signal. The noise source of the system is a pseudo noise generator that may be readily synchronized with an identical noise source or sources. The pseudo noise generator provides an apparently orderless noise-like sequence that may be exactly reproduced at the same or at a remote location or locations.

Abstract: A radar system (10) which transmits a random noise signal. The transmitted signal is embodied as an electromagnetic signal and is directed at an object or target. The object or target reflects at least a portion of the electromagnetic signal which is returned to the radar system. An image of the electromagnetic random noise signal is stored in memory (16) and compared with the returned modulated signal. Based on the correlation value, a determination is made regarding the object or target. In a particular implementation, the radar system is used in a target detection device (TDD) (10) in order to determine the distance from the target or object to the device and the relative velocity of the target or object and the device. When the target or object reaches a predetermined distance and also satisfies any other system requirements, the TDD (10) initiates a detonation signal which causes detonation of the missile or warhead.

Abstract: A system is provided for generating multiple frequencies in a specified frequency band, with a specified step size between frequencies, in which the spectral purity of the frequencies is assured. The switching speed between frequencies is very fast, limited only by the speed of the switches used. In one embodiment, only five tones are generated as the base for the rest of the synthesis, in which the relationship of the five tones is f0+/−⅛f0 and +/−{fraction (1/16)}f0. The subject system in one embodiment, utilizes a channel synthesizer and a doppler offset synthesizer which may be utilized in air defense systems for generating the transmit channels to be able to permit a missile seeker to transmit a signal at the appropriate frequency. In one embodiment, spectral purity is achieved by providing a number of stages of up converting, expanding, and dividing down of an input signal.

Abstract: A radar system (10) which transmits a random noise signal. The transmitted signal is embodied as an electromagnetic signal and is directed at an object or target. The object or target reflects at least a portion of the electromagnetic signal which is returned to the radar system. An image of the electromagnetic random noise signal is stored in memory (16) and compared with the returned modulated signal. Based on the correlation value, a determination is made regarding the object or target. In a particular implementation, the radar system is used in a target detection device (TDD) (10) in order to determine the distance from the target or object to the device and the relative velocity of the target or object and the device. When the target or object reaches a predetermined distance and also satisfies any other system requirements, the TDD (10) initiates a detonation signal which causes detonation of the missile or warhead.

Abstract: (U) A system for protecting a strategic bomber approaching the field covered by an airborne surveillance radar is shown to include: A search receiver arrangement to detect interrogating pulses from such radar before detection by such radar is possible and to determine the range of such radar and an air-to-air guided missile adapted first to home on the source of the interrogating pulses and then to be guided to intercept by an active radar seeker.

Abstract: This invention identifies a process for determining the performance of radio frequency (RF) links in the Army's Enhanced Position Reporting System (EPLRS) with a high level of statistical confidence. The method includes determining a statistical difference between a mean propagation loss for an EPLRS RF link based on measured RF propagation loss and TIREM calculated RF propagation loss, establishing a margin of error based on said statistical difference to arrive at a confidence level of the RF propagation loss, determining a computed S/N based on the confidence level, for the benign and jamming case, and determining a PCOM value based on the computed S/N value.

Abstract: Stealthcraft are detected by illuminating backgrounds with narrow radar or sonar beams and monitoring this background illumination for the changes that result when these beams are absorbed by such targets, and are ranged by triangulation using two such beams.

Abstract: A method of operating a radar to track echo signals from a target in the presence of a barrage jammer is shown to comprise the steps of actively determining the apparent direction of the combination of echo signals from a target and jamming signals, passively determining the actual direction and average power of a barrage jammer, calculating, from the foregoing, the actual direction of the target and instituting range and angle tracking of the target when the target is clear of the jamming signals.

Abstract: This array antenna with anti-jamming in reception for radioelectrical or ultrasound waves is provided with radiating elements fitted out individually or in groups with amplitude-controlled and phase-controlled passive or active modules enabling aiming at transmission as well as at reception by analog beam-forming. It possesses a reception anti-jamming circuit carrying out successively two reduced, adaptive computational beam-forming operations, one in elevation which is performed on a grouping, in horizontal alignments, of the reception signals of the radiating elements and working on the reception signals by modifying the settings of the controlled modules and the other in relative bearing, performed on a grouping, in vertical alignments, of the signals of the radiating elements that which it phase-shifts and adds up to form a reception channel for the total antenna.

Abstract: An intermediate frequency sidelobe canceller of the kind including a cancellation loop and switch means for sampling and holding correlation weights present in the loop, affording enhanced cancellation and reduced loop lock-on time. This capability is achieved by provision of means for control of the sample-hold switch means so as to limit duration of the sampling interval to an optimum value substantially shorter than the loop stabilization time. Such shorter sampling interval may be either of fixed duration or adaptively controlled in response to one or more loop operating parameters.

Abstract: In a vehicle designed for the execution of a mission, a programmable decision unit capable of managing and controlling the execution of the mission by utilizing a plurality of subsystems and database capable of holding and managing data including pre-stored data and data acquired by and received from the plurality of subsystems. The programmable decision unit includes a mission plan (MP) for accomplishing the execution of the mission includes a succession of iterations that include each assignment of a mission segment associated with a current mission stated to one or more of the subsystems. Each iteration further includes receipt from the subsystems report data which include data indicative of the execution status of the mission segment by the corresponding subsystem; and evaluation of the report data for determining either normal behavior or an exceptional event.

Abstract: Apparatus and method for eliminating an interference signal from a desired signal where a difference of polarization exists or can be made to exist. The desired signal is received on a first antenna of appropriate polarization and the interference signal is received via another port of the same antenna or a second antenna polarized ninety degrees away from the first. The signal received via the other polarization is adjusted for amplitude and phase so that all interference will be cancelled when both signals are subtracted in a summing junction. In the case where the interference and desired signals do not have polarization differences, provision is made to change the polarization of the desired signal.

Abstract: A monopulse system generates sum (.SIGMA.), elevation difference (.DELTA..sub.EL), azimuth difference (.DELTA..sub.AZ), and double difference (.DELTA..sub..DELTA.) signals, and generates a covariance matrix. The covariance matrix is decomposed to produce at least the principal eigenvector. The location or angular direction within the main beam of a single target is determined from the real component of the quotient of elements of the principal eigenvector, by the use of a look-up table. In another embodiment of the invention, the eigenvalues are generated from the covariance matrix, and the number of significant eigenvalues determines the number of targets within the main beam. If a single target is found, its location is found as described above. If two targets are found in the main beam, the locations of the two targets are determined by a closed-form solution of quadratic equations.

Abstract: A radar or GPS receiving system uses an antenna array to produce multiple antenna beams directed toward multiple targets or spacecraft. Stand-off jammers produce signals which tend to be received on the sidelobes of the antenna beams and to disrupt system operation. An array of autonomous or adaptive nullers process the received signals to produce weights which adjust the antenna nulls to direct them toward the jammers. The antenna nulls of one beam pattern are compared with the nulls of other beam patterns. Normal between-sidelobe nulls will not occur at the same angle on all of the patterns, but those nulls generated by the nullers will occur at the same angle. The directions to the jammers are deemed to be those directions in which all beam patterns have nulls.

Abstract: A transceiver system comprises transceivers and a controller in communication with the transceivers. Each of the transceivers comprises an emitter, a receiver operatively connected to the emitter, a primary data path operatively connected to the receiver, a secondary data path operatively connected to the receiver, a statistical unit operatively connected to the secondary data path and the controller and a display device operatively connected to the primary data path.

Abstract: The present invention provides a covert radar system in which radar signals emitted are capable to search receiver thermal noise and, therefore, are substantially undetectable in the normal radar operating range.

Abstract: Stealthcraft are detected by illuminating backgrounds with narrow radar or sonar beams and monitoring this background illumination for the changes that result when these beams are absorbed by such targets, and are ranged by triangulation using two such beams.

Abstract: A radio frequency navigation receiver has analog and digital sections. In the analog section, a CRPA antenna module receives global navigation signals and provides two steerable nulls for jammer suppression. An analog RF module has an amplifier and a YIG filter for amplifying and filtering an antenna output signal with jammer suppression. An analog receiver receives and downconverts an RF output signal from the RF system with additional jammer suppression. The analog receiver provides broadband signal filtering with at least 30 dB rejection and narrow band signal filtering with at least 45 dB rejection.In the digital section, a digital receiver module receives and converts an analog receiver output signal to generate a digital output signal for navigation control. A configuration manager processor responds to detected jammer signals to configure the receiver modules accordingly.

Abstract: An ink jet printer including a feed roller for feeding paper to a print area where print is effected by an ink jet head, a transparent roller to transport the paper which rotates at a peripheral speed faster than a feed roller, and an ink shielding portion positioned between the paper the print area and the ink jet head. The ink jet printer may also include a shaft which supports starwheels at the ends thereof, the central portion thereof being urged toward a plurality of paper discharge rollers.

Abstract: An adaptive receiving antenna reduces interference arriving in the main beam of the antenna by redirecting the antenna beam away from the interference source. The receiving antenna projects the main beam to receive desired source signals from a source direction and may receive interfering signals from the interfering source. The antenna system measures the strength of the source signal and interference signal for controlling the direction of the main beam to marginally decrease the received desired source signal while substantially decreasing the received interfering signal to increase the desired source signal to interfering signal ratio so that the desired source signal can be received in the presence of interference.

Abstract: A countermeasure-detecting circuit, and associated method, for a laser speed detector. Countermeasures taken at a moving target, such as a vehicle, to interfere with operation of the laser speed detector are detected. When countermeasures taken at the moving target are detected, the sensitivity of the laser speed detector is altered to overcome the effects of the countermeasures.

Abstract: A method of reducing the effects of interference on a radio receiver having access to multiple transmission sources including the steps of monitoring the signals received from all available sources, utilising information derived from the received signals from each source to compute the most likely frequency band of the interference, determining from said most likely frequency in conjunction with known ephemeris for the receiver and the current Doppler shift of the source signals which sources are least susceptible to interference at said most likely frequency, and passing the identities of said least susceptible sources to the receiver acquisition software.

Abstract: An integrated aircraft survivability equipment state machine. Aircraft survivability sensors provide aircraft survivability states that are routed to a finite state machine. Data processing, data generation, data representation, queueing tactical information and initiation of aircraft survivability counter measures are controlled by the state oriented approach. Systems state can be altered based on mission defined variables. Counter measures can be initiated based on correlated threat data and other functions such as failure recording and threat database generation functions. All individual aircraft survivability subsystems are integrated and controlled by the state machine. The state machine manages the ASE subsystem power as far as built-in testing and controls for the integrated ASE system. Overall threat data presentation is controlled and driven by the system state.

Abstract: In a radar, a protective radome is placed in front of a to-be-protected antenna. The antenna is made of several networks that are superimposed. At least one of the active networks can be controlled electrically in two distinct states A or B. In state A, the radome, which is placed in front of the antenna, is transparent for the radar operation frequency band and reflective outside that band. For state B, the radome is reflective for all radar frequencies. The invention especially protects the radar against jammers that transmit outside the radar operation frequency band, while providing for the total camouflaging of the radar when it is not being used.

Abstract: Aircraft survivability system state management is based on system mode, time, altitude, aircraft position, reference radius, and manual aircraft survivability equipment configuration select. The system mode is used with a segment number to begin system configuration sequencing of a segment pointer. A mission aircraft survivability system configuration plan comprises a number of segments of a mission plan. Each segment contains information such as the time, altitude and position for each segment. The segment is displayed in an active configuration and a next configuration on an aircraft survivability equipment display. When the aircraft enters a detection window the segment pointer is updated by an aircraft survivability system mode control processor. The system may be placed in either automatic mode or manual mode.

Abstract: Aircraft survivability embedded data recorder for threat data. The embedded threat data recorder stores active threat data generated by aircraft survivability equipment sensors. Threat data from a radar warning receiver, a pulsed radar jammer, continuous wave radar jammer or missile approach detectors are recorded by the embedded threat data recorder. The threat data for each sensor is correlated between each sensor to ensure that redundant threats are eliminated. The threat data recorder represents the recorded threats on a display for mission briefing, evaluating countermeasure effectiveness, or identifying new threats. The embedded threat data recorder also provides downloading of threat data into a threat data transfer cartridge for use in off-line threat analysis. Data can be provided to other platforms, satellites and ground base stations. Data can be recorded on a multifunction display and data compression techniques may be used. The tape may also be played back in the aircraft.

Abstract: Improved automatic gain control for an amplifier is obtained by controlling the size of a null zone in a drive signal for the amplifier. The size of the null zone is controlled by estimating strength of an interference signal, and dynamically varying the size of the null zone based on the estimated strength of the interference signal. As a result, the amplifier rarely saturates, regardless of signal strength. The invention is useful to reduce the harmful effects of jamming or interference.

Abstract: A spatial combiner for connection to a receiver used in conjunction with a lurality of direction-sensitive antennas for receiving a spread-spectrum communication signal in the presence of interference includes a steering network, a plurality of normalizers, and a plurality of combiners. The steering network combines N inputs from N antennas and produces outputs J.sub.1, J.sub.2, . . . , J.sub.M, with M being a multiple of K and K a positive integer such that each M output is a weighted sum of N inputs from the antennas. The normalizers receive and normalize the M outputs to unit energy and produce normalized outputs J .sub.1, J .sub.2, . . . , J .sub.M. The combiners receive normalized outputs and sum the first K outputs to produce output C.sub.1, sum the next K outputs to produce output C.sub.2, and continuing summing outputs in the same manner until summing the last K outputs occurs to produce output C.sub.M/K. The outputs C.sub.1 through C.sub.

Abstract: A sidelobe canceller system utilizing directional auxiliary antennas and e delays allows the spacing between the auxiliary antennas and a main radar antenna to be increased. This improves cancellation of multiple interference signals from the sidelobes of the main antenna.

Abstract: Apparatus and method for eliminating an interference signal from a desired signal where a difference of polarization exists or can be made to exist. The desired signal is received on a first antenna of appropriate polarization and the interference signal is received via another port of the same antenna or a second antenna polarized ninety degrees away from the first. The signal received via the other polarization is adjusted for amplitude and phase so that all interference will be cancelled when both signals are subtracted in a summing junction. In the case where the interference and desired signals do not have polarization differences, provision is made to change the polarization of the desired signal.