Abstract: Described herein, amongst other things, are laser rangefinder decoy systems, devices, and methods which decoy a laser rangefinder from giving the correct range to a target. Embodiments of the systems may provide “ghost” signals which are perceived to be the target; may provide for inaccurate indications of motion of the target and/or ghost; and/or may hide a targets true signature in a modified signal.

Abstract: A system and method is provided for detecting emitter signals and for determining a scan strategy for a receiver system that receives such emitter signals. Data is provided that specifies one or more emitters or emitter types desired for detection. An algorithm evaluates the cost, in terms of receiver resources, of using one or more different detecting methods to create a receiver scan strategy for the desired emitters or emitter types.

Abstract: A system and method is provided for detecting emitter signals and for determining a scan strategy for a receiver system that receives such emitter signals. Typically, the minimum dwell duration of a dwell is the maximum pulse repetition interval (PRI) of the emitters that the dwell is intended to cover. However, it may be possible to reduce the minimum dwell duration when the overall probability of intercept of a particular dwell may be met with a shorter dwell duration. A system and method are provided to detect this condition and reduce the dwell duration of the dwell if appropriate.

Abstract: Targets imaged by radar systems typically have shadows associated with them. Target detection and identification is enhanced by analyzing the shadow characteristics of a suspected target. Features of the shadow cast by the suspected target enhance the identification process. Authenticating the suspected target shadow as being indeed cast by the target comprises a) Generating a radar image using radar returns, the radar image containing both the target and its suspected target shadow; b) Forming a pentagonal perimeter adjacent to the target (within the radar image), the pentagonal perimeter chosen to contain the suspected target shadow, the pentagonal perimeter separating the target from its suspected target shadow; c) Testing the suspected target shadow within said pentagonal perimeter to authenticate that the suspected target shadow is cast by the target. One aspect of the testing performed on the suspect target shadow uses a 2 by 2 dilation and majority filter.

Abstract: A system and method is provided for detecting emitter signals and for determining a scan strategy for a receiver system that receives such emitter signals. In one embodiment of the invention, a set of models is used to compute antenna characteristics as a function of frequency, gain, power, beam width, scan and polarization. Data such as actual antenna gain vs azimuth for several polarizations may also be used, thereby reducing the amount of data needed for the antenna modeling purposes.

Abstract: An electronic circuit for use in an anti-radiation missile system of the type which uses the electromagnetic transmissions of a target radar for guidance information, detects when the missile has flown into a target null and is no longer receiving energy from one of the main lobes or side lobes of the target radar transmitter. When this condition is detected, the circuit causes an attenuation in the epsilon error guidance signal to momentarily prevent guidance commands based upon the now suspect epsilon error signals from being implemented.

Abstract: A system and method is provided for detecting emitter signals and for determining a scan strategy for a receiver system that receives such emitter signals. A rule-based system is provided for determining how emitters should be detected by a detection system. Rules may be used to prioritize certain emitters with respect to other emitters. The rules may also specify parameters for emitter modes, such as probability of intercept, turn-on range, detect-by range, tolerance, tolerance direction, scan periods, and other parameters. The rules may be used to compute the revisit time for the receiver. Multiple sets of rules may be created and a scan strategy may be computed based upon the selected rule set.

Abstract: A system and method is provided for detecting emitter signals and for determining a scan strategy for a receiver system that receives such emitter signals. If a dwells assigned frequency bandwidth is small and not a multiple of the minimum frequency spacing between dwells (tuning step), then coverage gaps can be inadvertently introduced between adjacent dwells. A system and method are provided for detecting this condition and generating dwells without accidental loss of frequency coverage for any combination of bandwidth and step size.

Abstract: A system and method is provided for detecting emitter signals and for determining a scan strategy for a receiver system that receives such emitter signals. However, it is possible that the scan strategy is not realizable because of capacity constraints within the receiver system itself. One embodiment of the invention provides a method for detecting and correcting such a situation.

Abstract: A sensor cover is disclosed for camouflaging a high frequency sensor, including for example, a radar sensor. The sensor cover includes a substrate having a non-planar surface with non-signal transmitting regions and signal transmitting regions. A metal layer is disposed on each of the non-signal transmitting regions. Further, each of the non-signal transmitting regions is separated by one of the signal transmitting regions. The method of constructing such a sensor cover is also disclosed.

Abstract: A rapidly deployable camouflage device for concealing recognizable signatures of military objects, comprising a camouflage balloon (1) and a deployment and undeployment device, the latter being equipped with a housing (2) and a fan (3) for inflating the balloon (1) arranged on an opening (4) in the housing. According to the invention, the balloon can be pulled into the housing by means of pull lines (7) secured at one end to the inside of the balloon opposite the opening (4), and at the other end to a motor-driven winding device inside the housing (2). The balloon is thus pulled in in such a way that it is reversed inside the housing, from which state if can then be blown out unreversed as rapidly deployable camouflage.

Abstract: An apparatus for electronic warfare signal simulation which is used in an external test system to simultaneously test a plurality of “victim” communication systems for vulnerability to jamming. The test system includes a remote radiator of a signal free of jamming effects, and a remote radiator of one or more radio frequency control signals which represent one or more predetermined jamming threats in the low and mid bands.

Abstract: A bi-static radar system is disclosed. The bi-static radar system comprises a system of positioning signal transmitters transmitting positioning signals, at least one of the positioning system signal transmitters being carried on a pseudolite. The bi-static radar system also comprises a receiving platform, the receiving platform having at least two antennas, a first antenna receiving positioning signals from the positioning signal transmitters, and a second antenna receiving reflected positioning signals from a target.

Abstract: The Electronic Support Measure (ESM) system is disclosed having various embodiments all of which reduce or even eliminate the detrimental effects caused by interference signals commonly generated by CW emitters.

Abstract: In regard to radar guidance of a launch container (15) for fragmentation projectiles (16) for defending against an attacking missile (12), from the object (11) to be protected, the present invention affords a radar guidance system which can be inexpensively set up from existing components and which, in the absence of interfaces between the object (11) and the launch container (15), operates in a trouble-free manner if, for space monitoring and target acquisition, provided on the substructure (14) of the launch container (15) which is fixed with respect to the object, there is a planar antenna (20) which transmits its target information to a target-tracking radar (19) which is integrated into the launch container (15), for directly guiding the launch container (15) on to the approach of the missile (12) to be defended against.

Abstract: A system for determining the scan type of a signal, such as a radar signal, includes a scan detector, a transformer (e.g., an FFT algorithm), a correlator, and a decision block. The signal is received and processed by the scan detector. The scan detector provides an envelope signal, representing the scan type of the received signal. The envelope signal is transformed, typically from a time domain signal to a frequency domain signal, by any of several processes including a Fourier transform, a Laplace transform, an FFT, or a DFT. The transformed envelope signal is compared to several scan data sets by the correlator. Each scan data set represents a particular scan type. If the decision block determines that the comparison between the transformed envelope signal and a scan data set meets (or exceeds) a degree of similarity, the scan type of the received signal is determined to be the scan type of that scan data set.

Abstract: A system and method for detecting a radar target of interest in the presence of radar jamming interference include a sub-array beamformer, a sum and difference beamformer, a weight calculator, a composite beamformer, and a monopulse ratio calculator. A plurality of sub-arrays is formed from antenna array element data. Respective sum and difference beams are formed for each of the plurality of sub-arrays. A single weight is formulated from the sum and difference beams, respectively. Composite sum beams are formed in accordance with the sum weights and the sum beams, and composite difference beams are formed in accordance with the difference weights and the difference beams. Composite beams are formed such that at least one null of each of the composite beams is steered toward an interference and a boresight gain of each of the composite beams is maintained.

Abstract: A method for determining a location of an emitter in a monitored area includes the step of providing an array representative of the monitored area, the array including a plurality of elements. Next, at least one first curve and at least one second curve is provided in the array. The first and second curves are representative of possible locations of the emitter in the monitored area. Then, possible emitter locations are identified at intersections of the first and second curves. The intersections are identified by determining locations in the array where an element having an assigned attribute corresponding to a first curve has a predetermined number of adjacent elements having an assigned attribute corresponding to a second curve.

Abstract: A Fourier transformation system usable for example in an electronic warfare radio receiver for analyzing spectral content of multiple transmitter-sourced brief duration incoming signals for characteristics including frequency component and frequency component amplitude content. The Fourier transformation system includes a plurality of approximated Kernel function values disposed at a plurality of locations about a real-imaginary coordinate axis origin and displaced from the origin by magnitudes having real and imaginary component lengths of unity and powers of two. Multiplication involving a power of two component during a Fourier transformation are achieved in a simple manner commensurate with a multiplication by unity in complexity but involving a binary number shift multiplication operation in lieu of a full fledged digital multiplication. Signal results comparisons with more simplified and more complex Kernel function approximations are also included.

Abstract: The two-piece end cap assembly has an end cap that has a groove around its perimeter and at least one cavity. The end cap is fixed in place inside the flare case with the cavities exposed. Sealant/adhesive is applied to the groove and cavity. A RAM cap, having a flange on its edge corresponding to the size of the flare case and a number of projections corresponding to the cavities, is installed on the top surface of the end cap. The sealant/adhesive in the cavities attaches the RAM cap to the end cap. The sealant/adhesive in the groove is forced to the edges of the end cap and provides a seal between the end cap and the flare case. Radar Absorbing Material is applied to the top and exposed edges of the RAM cap, completely masking the face of the flare and its edges.

Abstract: An inexpensive, small, low-power consumption, wide-band, high resolution spectrum analyzer is provided as a listening device for throw-away applications such as surveillance that involve deployment of large numbers of battery-powered spectrum analyzer modules to detect a signal source such as two-way radio traffic. Power requirements are minimized by the utilization of only one chirp generator to elongate battery life while providing a high resolution result. In order to minimize power drain the spectrum analyzer includes a single compound-chirp Fourier Transform generator. The compound chirp generator is used in one embodiment with a surface acoustic wave, SAW, dispersive delay line in conjunction with a surface electromagnetic wave, SEW dispensive delay line.

Abstract: An RF band receiver for concurrently monitoring a plurality of contiguous channels within the RF spectrum to unambiguously detect time-coincident signals. The receiver includes a plurality of transmission paths feeding a like number of digital, mixed-base code channels. Each mixed-base code channel includes a harmonic mixer, an IF amp, a plurality of bandpass-filters and a like plurality of detectors. The outputs of the detectors for each mixed-base code channel are fed to a frequency sorter whose output is a digital frequency word which indicates the frequency(s) of the received signal(s).

Abstract: A pulse Doppler radar receiver is disclosed wherein monopulse sum and difference signals are time-multiplexed and passed through a single gain-controlled amplifier channel for normalization, the sum signal being processed to provide both a D.C. gain control signal for such channel and a reference signal for demodulating the difference signal.

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: Radar Pulse detection and radar signal length detection are used to detect and provide information for identifying radar signals. Pulse detection estimates a radar pulse size when it is too short for meaningful measurement. Pulse detection identifies a radar by identification of an in-band pulse without a communication or data packet encoded therein, or a communication error is detected with the in-band pulse. Signal length detection counts the length of a received signal after the received signal exceeds a radar threshold. The count identifies the received signal length upon drop of the power. The signal is identified as a radar when the power drops before a PHY error occurs, or when the power drop occurs after a PHY error and a delay time equivalent to the shortest radar signal. A radar signal is also identified upon a timeout wait for a power drop after a PHY error.

Abstract: A passive radar decoy for deployment from an aircraft in flight comprises a substantially hemispherical body having its inner surface coated with an RF reflective material and its forward end connected to a weighted nose piece. The decoy is ram-air inflatable and is packaged with a plurality of chaff in the aircraft within a radar countermeasures ejection tube. Upon ejection from the aircraft, the decoy achieves RF coverage at millimeter wave frequencies and improves chaff dispersion and an increased period of doppler frequency return to a ground-based radar. The decoy may also include a second hemispherical body mounted at the approximate focus within the inflatable body and having its outer surface RF reflective so as to retroreflectively return RF energy impinging on the decoy and the combined returns from the decoy provide a scintillating signal return to the ground-based radar.

Abstract: An inexpensive, small, low-power consumption, wide-band, high resolution spectrum analyzer is provided as a listening device for throw-away applications such as surveillance that involve deployment of large numbers of battery-powered spectrum analyzer modules to detect a signal source such as two-way radio traffic. Power requirements are minimized by the utilization of only one chirp generator to elongate battery life while providing a high resolution result. In order to minimize power drain the spectrum analyzer includes a single compound-chirp Fourier Transform generator. The compound chirp generator is used in one embodiment with a surface acoustic wave, SAW, dispersive delay line in conjunction with a surface electromagnetic wave, SEW dispensive delay line.

Abstract: A digital polarimeter employs a signal time stretching technique to apply polarization phase shift characteristics to digitally generated polarization agile signal components. An RF signal to be transmitted is down-converted to an intermediate frequency and digitally sampled at a rate feasible with currently-available analog-to-digital converters. Horizontal and vertical signal components of the sampled IF signal are generated by processing the digital signal samples. Each digital signal sample is “time stretched” by storing each sample in M memory locations, such that N samples occupy M×N memory locations. Because each sample is stored in M memory locations, each incremental phase shift from one memory location to the next corresponds to 1/Mth of the actual sampling interval. The stretching process effectively increases the digital sampling frequency, yielding sufficient phase resolution.

Abstract: A combined defense and navigational system on a naval vessel is disclosed. The disclosed system includes a track-while-scan pulse radar which is controlled to provide either navigational information or tracking information on selected targets. Additionally, the disclosed system includes a plurality of guided missiles, each of which may be vertically launched and directed toward intercept of a selected target either by commands from the track-while-scan radar or from an active guidance system in each such missile.

Abstract: The present invention consists of the particular geometry of the reflectors or dispersers which constitute the anti-radar chaff cloud. Instead of using conventional rectilinear forms, in the present invention multilevel and space-filling forms are introduced. Due to this geometric design, the properties of the radar chaff clouds improve mainly in two aspects: radar cross-section (RCS) and mean time of suspension.

Abstract: In regard to radar guidance of a launch container (15) for fragmentation projectiles (16) for defending against an attacking missile (12), from the object (11) to be protected, the present invention affords a radar guidance system which can be inexpensively set up from existing components and which, in the absence of interfaces between the object (11) and the launch container (15), operates in a trouble-free manner if, for space monitoring and target acquisition, provided on the substructure (14) of the launch container (15) which is fixed with respect to the object, there is a planar antenna (20) which transmits its target information to a target-tracking radar (19) which is integrated into the launch container (15), for directly guiding the launch container (15) on to the approach of the missile (12) to be defended against.

Abstract: According to the invention, there is provided a device enveloping said superstructure and able to reflect electromagnetic waves, said device comprising a truncated pyramidal frame (6) and a net (7) covering the small base of said frame (6).

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: A combined defense and navigational system on a naval vessel is disclosed. The disclosed system includes a track-while-scan pulse radar which is controlled to provide either navigational information or tracking information on selected targets. Additionally, the disclosed system includes a plurality of guided missiles, each of which may be vertically launched and directed toward intercept of a selected target either by commands from the track-while-scan radar or from an active guidance system in each such missile.

Abstract: The present invention relates to a method for identifying modern radar systems. A finite state automaton comprising a finite set of states and a set of transitions from state to state that occur in dependence upon an input signal is provided for modeling the radar system. The finite state automaton produces a sequence of output symbols from an output alphabet in dependence upon the state transitions such that the sequence of output symbols corresponds to a received electromagnetic signal emitted from the radar system. The finite state automaton is then transformed into a hidden Markov model such that a sequence of observation symbols produced from an observation alphabet by the hidden Markov model is equal to the sequence of output symbols. The method provides powerful tools for solving electronic warfare problems such the classification problem, the decoding problem, the prediction problem and the training problem.

Abstract: A combined defense and navigational system on a naval Vessel is disclosed. The disclosed system includes a track-while-scan pulse radar which is controlled to provide either navigational information or tracking information on selected targets. Additionally, the disclosed system includes a plurality of guided missiles, each of which may be vertically launched and directed toward intercept of a selected target either by commands from the track-while-scan radar or from an active guidance system in each such missile.

Abstract: A mobile radar system including Electronic Support Measures (ESM) which is adapted to detect and decode Identify Friend or Foe (IFF) signals. The system includes means for decoding or decrypting received IFF signals. The system uses an Electronic Counter Measure (ECM) transmitter which is adapted to transmit IFF response and interrogation signals. The IFF signals to be transmitted can be encrypted. Integrating IFF means into the ESM and ECM components results in mass and volume savings due to shared use of the transmitting and receiving resources. As the IFF signals are transmitted using ESM antennas, they can be directed towards a particular aircraft, thereby reducing spurious transmissions.

Abstract: There is provided an autonomous off-board defensive aids system (100) for use with a host craft (102), for example, with combat aircraft or submarines. More particularly, the host craft (102) deploys a plurality of controllable off-board units (104, 106) to counter an offensive threat or to engage in autonomous offensive actions. The controllable off-board units (104, 106) implement active stealth facilities: each off-board unit (104, 106) having a receiver unit for detecting impinging detection pulses, for example radar or sonar pulses, and a transmitter unit for generating an artificial detection pulse profile, for example “spoofing” or masking the presence of the host craft. The controllable off-board units are of two types: tethered (104) and free moving (106). The off-board units (104, 106) can have conventional propulsion apparatus, for instance, propellers, rockets or jets. Off-board units (104, 106) each have control apparatus which allows the off-board units (104, 106) to co-operate.

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 radar detector system comprises a multi-band patch antenna assembly. The multi-band antenna assembly includes a plurality of patch antennas. Each patch antenna is adapted to receive a radar signal at a specific frequency band. Each patch antenna is further adapted to receive a radar signal in response thereto provide patch antenna output signals. Each patch antenna has a plurality of patches. The patches increase electronic gain. The patch antenna assembly also includes a combining network to receive the patch antenna output signals and then create and forward a single patch antenna assembly output signal.

Abstract: A system for determining the scan type of a signal, such as a radar signal, includes a scan detector, a transformer (e.g., an FFT algorithm), a correlator, and a decision block. The signal is received and processed by the scan detector. The scan detector provides an envelope signal, representing the scan type of the received signal. The envelope signal is transformed, typically from a time domain signal to a frequency domain signal, by any of several processes including a Fourier transform, a Laplace transform, an FFT, or a DFT. The transformed envelope signal is compared to several scan data sets by the correlator. Each scan data set represents a particular scan type. If the decision block determines that the comparison between the transformed envelope signal and a scan data set meets (or exceeds) a degree of similarity, the scan type of the received signal is determined to be the scan type of that scan data set.

Abstract: A system for determining the scan type of a signal, such as a radar signal, includes a scan detector, a transformer (e.g., an FFT algorithm), a correlator, and a decision block. The signal is received and processed by the scan detector. The scan detector provides an envelope signal, representing the scan type of the received signal. The envelope signal is transformed, typically from a time domain signal to a frequency domain signal, by any of several processes including a Fourier transform, a Laplace transform, an FFT, or a DFT. The transformed envelope signal is compared to several scan data sets by the correlator. Each scan data set represents a particular scan type. If the decision block determines that the comparison between the transformed envelope signal and a scan data set meets (or exceeds) a degree of similarity, the scan type of the received signal is determined to be the scan type of that scan data set.

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: According to the invention, there is provided a device enveloping said superstructure and able to reflect electromagnetic waves, said device comprising a truncated pyramidal frame (6) and a net (7) covering the small base of said frame (6).

Abstract: A passive radar decoy comprises a substantially hemispherical upper body portion having its inner surface coated with an RF reflective material, a weighted nose piece, a tapered lower body portion interconnecting the upper body to the nose piece, an RF reflectively-coated corner reflector mounted coaxially within the upper body portion, and means to ram-air inflate the decoy when it is released from an aircraft in flight such that RF energy from a ground source of such energy impinges on the RF reflective surfaces to retro-reflectively return the RF energy back to the source and provide a scintillating and doppler frequency return and enhanced radar target cross section.

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 radar for locating and tracking objects based on the use of a pulsed waveform, each pulse of the pulsed waveform being made up of a plurality of spectral components having different frequencies, including an antenna. The radar further includes a transmitter operatively coupled to the antenna for generating the plurality of spectral components that make up each pulse of the pulsed waveform and a receiver operatively coupled to the antenna for receiving signals at the frequencies of the plurality of spectral components.

Abstract: Disclosed is a device to conceal a radar fitted for example into a vehicle. This device bears especially a pattern. A method to make such a device is also disclosed. The device reproduces a given pattern comprising a shiny part. It comprises at least one front part transparent to optic waves and one part having a face with a shiny appearance before the rear face of the front part. The non-shiny part of the pattern covers the rear face of the front part. The invention can be applied especially to radars positioned on the front of vehicles. The cover then reproduces the manufacturer's logo.

Abstract: A non-skid, radar absorbing system 10. The system absorbs and scatters incident microwave and/or millimeter wave radiation so as to decrease retro reflectance. The system includes an absorbing layer (RAM) 14 juxtaposed with a substrate 12. Disposed adjacent the RAM 14 is a non-skid matrix layer 16 for providing a safe foot hold. Optionally, a protective environmental topcoat 18 is applied to the non-skid layer 16. The system has electrical and magnetic characteristics such that radar energy at a discrete or broadband frequencies is at least partially absorbed. The invention also includes methods of making and using the non-skid, radar absorbing system 10.