Abstract: In one implementation, a wireless communications terminal includes a multi-element antenna. In addition, the terminal includes preliminary signal combiners to combine received signals output by corresponding pairs of antenna elements. For each preliminary signal combiner, the signal output by a first of the pair of elements provides a model of interference present in the received signal output by the second of the pair of elements. The preliminary signal combiner is configured to combine the signal output by the first element with the signal output by the second element to produce an initial interference-mitigated signal.

Abstract: A system and method for testing the integrity of signals incoming to a satellite navigation system. The method is implemented with an array of antenna elements, and a receiver connected to each antenna element. The receivers simultaneously and continuously make measurements on all tracked signals. Each receiver measures the carrier phase of an incoming signal. Based on the carrier phase differences between antenna elements and the distance between them, the azimuth and elevation of the signal source can be calculated. This measured angle of arrival can then be compared to an expected angle of arrival to determine if the signal source is legitimate. The system and method can be also applied to determining the angle of arrival of sources of interference, and to mitigating the effects of both illegitimate and interfering signals.

Abstract: Implementations described and claimed herein provide systems, apparatuses, and methods for ultrasonic object detection. In one embodiment, a sensor includes at least two transducers driven by a common waveform generator and configured to process received echoes, from an object, using a common echo detector. By providing the wavefront 180 degrees out of phase to one transducer relative to the other transducer, a dual detection lobe may be provided and thereby provided two detection volumes. By varying the phase delay from one transducer relative to other, the detection beam (volume) may be steered or swept. Without phase delay, a relatively higher strength acoustic detection signal may be transmitted by the two or more transducers.

Abstract: Position tracking systems comprising one or more emitters comprising one or more emitter magnetic loops, one or more receivers comprising one or more receiver magnetic loops and a processing unit and a processing unit comprising a mixed signal circuit, wherein the one or more emitters and the one or more receivers each further comprise one or more electromagnetic absorbers and electromagnetic blockers which are configured to ensure the respective emitter and receiver magnetic loops emit a magnetic field on their own plane. The one or more receiver magnetic loops, the one or more second electromagnetic absorbers, and the one or more second electromagnetic blockers are placed in between the one or more receivers to increase differences in the strengths of the incoming magnetic field such that the differences in the strengths are measurable by mixed signal circuit.

Abstract: Systems and methods are provided for determining a direction of a signal received at an antenna array. An antenna array includes a plurality of antenna elements, including a reference element. A signal combiner element is configured to combine weighted signals from a subset of the plurality of antenna elements to provide a composite output. An adaptive processing component is configured to determine an optimal set of weights for the subset of the plurality of antenna elements. An angle of arrival search component is configured to find a direction of minimum gain given the optimal set of weights.

Abstract: Systems and methods are described using a Hermetic Transform, as well as related transforms, for applications such as directional reception and/or transmit of signals using phased-array devices and systems. The systems and methods an include identifying a direction of arrival for a mobile communicating device. The systems and methods also include the use of a noise conditioning matrix.

Abstract: Disclosed is a method of estimating a position of a signal source and a position estimation apparatus, the method including acquiring an environment, a frequency, and a bandwidth of the interference signal source, determining an arrangement form of the two antennas based on the environment, the frequency, and the bandwidth and arranging the two antennas, and estimating a position of the interference signal source based on an interference signal of the interference signal source and the two arranged antennas, wherein the environment includes an indoor environment and an outdoor environment.

Abstract: Methods and systems are described for transmitting data using various selected resources. For example, first one or more resources may be selected based at least in part on feedback from a first network node. A second network node may cause first data to be transmitted using the selected one or more resources. The second network node may also cause second data to be transmitted using second one or more resources. The resources may comprise, for example, tones, time slots, time-frequency channels, time resources, and/or frequency resources.

Abstract: Systems and methods for recovering rapidly from a mode-conversion of a common mode interference. One exemplary transceiver includes: a slicer configured to generate slicing decisions and slicing errors based on a differential signal, transmitted at a rate above 500 Mbps, which is received from a second transceiver; and a common mode sensor analog front end (CMS-AFE) configured to sense a common mode component of the differential signal. The CMS-AFE is coupled to a fast-adaptive mode-conversion canceller (FA-MCC) configured to generate a compensation signal that compensates for differential interferences that are correlated with the common mode component. Wherein, within less than 1 millisecond from an occurrence of a differential interference that causes the packet loss to exceed 10% as a result of the mode-conversion, the transceiver is configured to utilize the slicing errors to adapt the FA-MCC to a level that reduces the packet loss rate to below 1%.

Abstract: A portable device for wireless communication is disclosed. The portable device comprises an antenna array having N array elements distributed on and conforming to the surfaces of the portable device, N being an integer greater than 1. The N array elements output N signals to a frontend unit. The frontend unit receives the N signals and generates N digital signals. A digital beam forming network, coupled to the frontend unit, processes M digital signals selected from the N digital signals, M being an integer less than or equal to N, and generates K beams based on the M digital signals, K being an integer greater than 1. A controlling unit, coupled to the digital beam forming network, computes dynamically a beam weight vector for each of the K beams based on data on orientation and position of the portable device and data on geometry of the antenna array and hub directions. A position information unit, coupled to the controlling unit, generates the data on position and orientation of the portable device.

Abstract: An apparatus may include a plurality of antenna elements forming an antenna array. The apparatus may further include a beamformer that determines one or more of phase and amplitude shifts to cause the plurality of antenna elements to produce a beam in the direction of a target. The apparatus may further include a null limiter comprising dither circuits. The dither circuits may dither the one or more of phase and amplitude shifts by adding noise to cause a side lobe of the beam to increase above a threshold value. The dither circuits may be enabled by a control signal, and the dithered one or more of phase and amplitude shifts may be provided to the antenna elements to produce the beam in the direction of the target with the side lobes above the threshold value.

Abstract: An apparatus and digital signal processing means are disclosed for excision of co-channel interference from signals received in crowded or hostile environments using spatial/polarization diverse arrays, which reliably and rapidly identifies signals with transmitted features that are almost-periodic over known framing intervals, and exploits those features to develop diversity combining weights that substantively extract those signals from that environment, based on differing diversity signature, timing offset, and carrier offset of those signals. In one embodiment, the signal identification and extraction is performed in an appliqué that can be implemented without coordination with an actual radio transceiver.

Abstract: An antenna unit is used in an antenna array. It comprises a measurement signal receiver for receiving and digitizing a measurement signal from an antenna. A time delay unit delays the digitized measurement signal. A data collection receiver receives a data collection frame, and a data collection transmitter is configured to sum the delayed digitized measurement signal with pre-existing data in the received data collection frame and to transmit the so constructed updated data collection frame further.

Abstract: A system for indoor localization using satellite navigation signals in a Distributed Antenna System. The system includes a plurality of Off-Air Access Units (OAAUs), each operable to receive an individual satellite navigation signal from at least one of a plurality of satellite navigation systems (e.g., GPS, GLONASS, Galileo, QZSS, or BeiDou) and operable to route signals optically to one or more DAUs. The system further includes a plurality of remote DRUs located at a Remote location that are operable to receive signals from a plurality of local DAUs. Moreover, the system includes an algorithm to delay each individual satellite navigation signal for providing indoor localization at each of the plurality of DRUs.

Abstract: An adaptive analog parallel combiner circuit for receiver data recovery from a communication signal is provided. The circuit includes a summer that sums outputs of a plurality of filter taps in parallel, including zeroth and first through Nth filter taps, each filter tap having as input the communication signal or a version thereof, wherein N is a finite integer greater than or equal to two. The zeroth filter tap has an amplifier with gain controlled by a zeroth adaptive gain control coefficient, and each of the first through Nth filter taps having an all pass filter and gain controlled amplification, with gain controlled by a corresponding one of a first through Nth adaptive gain control coefficients and the all pass filter implementing a transfer function having a zero and a pole equaling each other and at a base frequency divided by a corresponding integer from one through N.

Abstract: An angularly resolving radar sensor having multiple antenna elements that, in a direction in which the radar sensor is angularly resolving, are disposed in different positions, and having a control and evaluation device that is designed for an operating mode in which several of the antenna elements transmit signals that are respectively received by several of the antenna elements, and the angle (?) of a located object is identified on the basis of amplitudes and/or phase relationships between signals which correspond to different configurations of transmitting and receiving antenna elements, wherein the control and evaluation device is embodied to supply several of the transmitting antenna elements simultaneously with identical-frequency signals (f1-f4) in such a way that the common phase center of said signals is located between the positions of two adjacent antenna elements.

Abstract: The present invention relates to a method for determining a direction to a signal-emitting object by means of a platform comprising at least two antennas separated by a known distance. The method comprises said steps of: receiving, with each of said at least two antennas, a signal from said signal-emitting object at first positions, determining a first phase relation of said signal between said at least two antennas, —receiving, with each of said at least two antennas, a signal from said signal-emitting object at at least second positions, determining at least a second phase relation of said signal between said at least two antennas, characterized by the steps of: determining change(s) in position(s) of at least one antenna of said at least two antennas, and determining a direction to a signal-emitting object based on said first phase relation, said at least second phase relation and said change(s) in position(s) of said at least one antenna.

Abstract: A method for beamforming in a communication network includes generating a plurality of beamforming training (BFT) units associated with a beamforming session between a pair of devices, where each of the plurality of BFT units corresponds to a different beamsteering vector, causing a first non-zero subset of the plurality of BFT units to be transmitted during a first timeslot, and causing a second non-zero subset of the plurality of BFT units to be transmitted during a second timeslot, where the first time timeslot and the second timeslot are not contiguous.

Abstract: An adaptable orthogonal frequency-division multiplexing system (OFDM) that uses a multiple input multiple output (MIMO) to having OFDM signals transmitted either in accordance with time diversity to reducing signal fading or in accordance with spatial diversity to increase the data rate. Sub-carriers are classified for spatial diversity transmission or for time diversity transmission based on the result of a comparison between threshold values and at least one of three criteria. The criteria includes a calculation of a smallest eigen value of a frequency channel response matrix and a smallest element of a diagonal of the matrix and a ratio of the largest and smallest eigen values of the matrix.

Abstract: Methods for disambiguating the location of a radar contact using an N×M dimensioned radar array are provided. In the horizontal plane, the method comprises transmitting a first radar energy pattern in a direction, collecting reflected energy of the first radar energy pattern from the contact, transmitting a second radar energy pattern in the direction and collecting reflected energy of the second radar energy pattern from the contact. The method further comprises comparing the collected energy of the first radar energy pattern and the collected energy of the second radar energy pattern and determining if the contact is located in a side lobe or a main lobe of the first and second radar energy pattern based on the comparison. In the vertical plane, other similar embodiments may be used to determine if the radar antenna(s) are blocked by an obstacle.

Abstract: A wireless communication module comprising including a first transmission bandpass filter that takes a first transmit frequency band as a passband; a second transmission bandpass filter that takes a second transmit frequency band as a passband; a first reception bandpass filter that takes a first receive frequency band as a passband; a second reception bandpass filter that takes a second receive frequency band as a passband; and a plurality of switches, each switch connected to a single one of the bandpass filters.

Abstract: An array of elements suitable for adaptive processing in an extreme jammed environment comprised of a plurality of smaller sub-arrays of element clusters that have natural orthogonal spatial modes of excitation, wherein the improvement comprises sub-arrays with spatial orthogonality of feed modes, cross-sub-array combination to maximize pre-processing sub-array spacing and diversity of relative configuration, a high-input analog nuller used on the pre-processing sub-array therein, a high-input analog nuller is used to null a dominant jamming signal, possibly exceeding normal communication signal levels, so that the sub-array processed signals could then be fed to an antenna processor with simultaneous beam steering and null steering.

Abstract: A circuit may be configured to adaptively combine two or more waveforms into a single waveform. The circuit can generate weighting factors based on received error signals, and can apply the weighting factors to the two or waveforms to be combined.

Abstract: A packet data transmission system comprises primary stations (PS) having signal transmitting and receiving means and antennas (PA1 to PA4) for propagating downlink signals and receiving uplink signals and a plurality of secondary stations (SS) able to roam within the coverage areas of the primary stations. Each secondary station (SS1) has signal transmitting and receiving means, a predetermined number of antennas (SA1 to SA4), and means for monitoring its radio environment. Information about the radio environment is relayed as an uplink signal to the respective primary station which modifies its mode of transmission of packet data signals. The secondary station in response to the modified mode of transmission of the downlink signals adapts its receiver resources to process the packet data signals and effect cancellation of any interference.

Abstract: A radio base station 100 judges a receiving state of a radio signal in conformity with the orthogonal frequency division multiplexing scheme, and changes a symbol string configuration of a symbol string defined by a size in a frequency axis direction and in a time axis direction, on the basis of the judged receiving state.

Abstract: In one or more embodiments described herein, there is provided an apparatus configured for use with one or more directional antennas. The one or more directional antennas each have a respective directional axis, a first sensitivity region being proximal to the directional axis and associated with a first variation in sensitivity across the first region, and a second sensitivity region being distal to the directional axis and associated with a second variation in sensitivity across the second region. The second variation in sensitivity is greater than the first variation in sensitivity. The apparatus is configured to discriminate one source of radio frequency identification signalling at a particular angular position from other neighboring sources of radio frequency identification signalling by using the alignment of one or more second sensitivity regions with respect to the particular angular position.

Abstract: Embodiments of the invention provide systems and methods for systems and methods for adaptively canceling interfering signals generated by a transmission antenna. Under one aspect, a system includes: an auxiliary antenna co-located with the main antenna, the auxiliary antenna configured to transmit an auxiliary signal to the victim antenna; a sensing antenna located on a line-of-sight path between the transmission antenna and the victim antenna, the sensing antenna configured to receive a composite of the interference and the auxiliary signal, and to output a first signal based on the received composite; a controller comprising an input coupled to the sensing antenna and configured to receive the first signal, the controller being configured to adjust at least one of an amplitude, a phase, a polarization, and a frequency characteristic of the auxiliary signal based on the first signal so as to reduce the composite of the interference and the auxiliary signal received by the sensing antenna.

Abstract: Embodiments include a method to suppress side lobes of a main antenna by creating cancellation directions using a Side Lobe Canceller (SLC). Various embodiments also provide the Side Lobe Canceller.

Abstract: This invention relates to the use of a sufficiently-sampled auxiliary array in combination with one or more under-sampled sub-arrays. The sufficiently-sampled auxiliary array is used to create a signal-free reference (SFR) beam that contains grating lobe interference. The SFR may be used to cancel the interfering grating lobe in an under-sampled main beam by coherently eliminating or subtracting the SFR from the main beam. Exemplary aspects of the invention thus support significant under population of the full aperture and avoid the problems and limitations of previous solution, with consequent savings in sensor hardware cost and weight.

Abstract: A method and system for communicating satellite digital radio program information for multiple satellite channels is provided. The method includes the steps of providing multiple satellite signals, and providing multiple data frames in each of the satellite signals. The method also includes the steps of providing frame synchronization symbols in each of the data frames, such that the frame synchronization symbols occurring in the satellite signals do not overlap in time with each other. The method also includes the steps of providing multiple data slots within each of the data frames, and providing satellite program information in at least one of the data slots in each data frame. The multiple data slots are positioned within each data frame relative to the frame synchronization symbol of that data frame, such that the data slots containing satellite program information in the multiple satellite signals do not overlap in time with each other.

Abstract: The invention provides a method for installing a positioning system, the positioning system comprising two or more base stations (BS1 to BS4), and comprises the steps of; collocating the base stations (BS1 to BS4); quantifying any lack of synchronization between the clocks of the base stations; relocating one or more of the base stations (BS2? to BS4?) to their fixed, operational positions and measuring the time of flight of a signal from each of the relocated base stations; determining from the time of flight and quantified lack of synchronization data the relative separation of the base stations (BS1, BS2? to BS4?) and hence the configuration of the installed positioning system, and recording the configuration of the installed positioning system.

Abstract: For detection of an electromagnetic signal, which is transmitted from a transmitting antenna (1), by means of at least two at least essentially identical receiving antennas (3, 4), whose sensitivity curve has a maximum (M) with falling flanks as well as sidelobes (SL) adjacent to it with sensitivity increased again at a reception angle symmetrically with respect to a basic alignment, with angle determination for an object which reflects the transmitted signal being carried out by the two receiving antennas (3, 4) by phase determination in an unambiguous interval (?u) whose boundaries (L) are predetermined by the distance (d) between the receiving antennas (3, 4), the distance (d) is chosen such that the boundaries (L) of the unambiguity area (?u) intersect the sidelobes (SL), and the reflective object is detected by means of vectorial addition of the signals from the receiving antennas (3, 4), after which the parameters R, v are determined.

Abstract: A combined SAIC receiver and a multiple-antenna, receive diversity receiver are employed to reduce interference in a wireless system. The real and imaginary parts of the de-rotated signal for each receive path associated with an antenna are separately filtered and a combined output signal of all receive paths is generated. The weighting coefficients are adjusted based on an error signal produced by comparing the combined output signal with a reference signal. The weighting coefficients are initially set based on an MMSE/LS type of signal processing criteria, where the reference signal is the Training Sequence Code (TSC). Subsequent adjustment/tracking can be accomplished by using known tracking algorithms, e.g. LMS or RLS, or the coefficients can be re-computed using MMSE/LS processing. The reference signal for tracking may be a combination of the TSC and estimated data symbols provided by an equalizer.

Abstract: The invention relates to an antenna (1) including: a first (2) and a second (3) linear sub-antenna equipped with sensors (21-2M, 31-3N) forming first and second line portions and generating a basic signal (Si?, Gj?), wherein the angle between the directional vectors of the first and second tangents to the midpoint of the first and second line portions is between 30° and 150°; a device for transmitting an electromagnetic signal at a frequency equal to at least 10 GHz; an antenna processing device (4, 5) forming a plurality of combined signals (VSi, VGj); a signal processing device (6, 7) generating combined signals (TSi, TGj); a device (8) for calculating the correlation coefficients ([Cij]) between the useful combined signals; a device (8) generating a detection signal ([Rij]) when a correlation coefficient exceeds a predetermined threshold.

Abstract: Various techniques are disclosed to suppress undesired signal components introduced by non-linear amplifiers of phased array antenna systems to accommodate bandwidths greater than one octave. For example, in accordance with one embodiment, a phased array antenna system includes first and second antenna elements adapted to provide first and second received signals in response to a radio signal. The second antenna element is rotated approximately 180 degrees in relation to the first antenna element. Amplifiers may amplify the received signals to provide amplified signals having a bandwidth greater than one octave. Undesired components of the amplified signals introduced by the amplifiers may be suppressed through appropriate phase shifts performed by associated phase shifters and/or power combiners.

Abstract: A positioning system receiver is disclosed. The positioning system receiver includes an antenna for receiving radio frequency (RF) signals. The positioning system receiver also includes a radio frequency front end system configured to convert the received RF signals into intermediate frequency signals. The positioning system receiver further includes a digital processing and correlation system, receiving the intermediate frequency signals and including a plurality of taps on the autocorrelation function main lobe and a plurality of taps on at least one of the autocorrelation function side lobes. The digital processing and correlation system uses the signals received from the taps in a dot product detector algorithm to improve the signal-to-noise ratio of the receiver system.

Abstract: A path search circuit according to the present invention has an orthogonal multi-beam forming section 4 for directional reception with a plurality of orthogonal multi-beams orthogonal one to another, correlation-operating sections 61–6M for correlation-operating outputs of the orthogonal multi-beam forming section 4 with a known signal, weight multiplying sections 81–8Nb for multiplying the output of the correlation-operating section 61–6M by a weight converted into a beam space, delay profile generating sections 91–9Nb for generating delay profiles from the output signals of the weight multiplying sections 81–8Nb, and a path detecting section 10 for detecting a reception timing and arrival direction of arrival path from the delay profile. This path search circuit can enhance the accuracy of path direction detection by the use of a directional reception signal, and further reduce the direction dependence of path timing detection accuracy.

Abstract: Techniques to correct for phase and amplitude mismatches in a radio device in order to maintain channel symmetry when communicating with another device using MIMO radio communication techniques. Correction for the amplitude and phase mismatches among the plurality of transmitters and plurality of receivers of a device may be made at baseband using digital logic (such as in the modem) in the receiver path, the transmitter path or both paths of that device. In a device, amplitude and phase offsets are determined among the plurality of radio transmitter and radio receiver paths by measuring phase and amplitude responses when supplying a signal to a transmitter in a first antenna path of the device and coupling the radio signal from a first antenna to a second antenna path of that device where the signal is downconverted by a receiver associated with the second antenna path, and similarly coupling a signal from the second antenna path to the first antenna path.

Abstract: A path detector detects multipath waves on a transmission line based on a plurality of despread signals corresponding to fixed directional beams. An adaptive beam forming section forms an adaptive beam combined signal for each path, using a weight generated by an adaptive algorithm and the despread signals. An adder combines the adaptive beam signal for all paths, and a data judging section judges data included in the combined signal.

Abstract: A steerable antenna array (10) includes a plurality of antenna elements (12a-12f) which receive broad band signals and narrow band interfering signals which together form antenna signals. The antenna signals are combined with weighting signals by combining functions (16a-16f) to form a combined signal, which is filtered by a filter function (30) to filter the narrow band signals. The filtered signals are sent to a weight processor (50) which also receives the antenna signals as an input. The processor (50) generates the weighting signals so that interference from the narrow band signals is reduced.

Abstract: The invention concerns a method and apparatus for cascaded processing of signals in a phased array antenna system in which a plurality of antenna elements are configured as a plurality of sub-arrays. A weighting factor is applied to each of the antenna elements to form a plurality of sub-array beams, each pointed in a selected direction. For each sub-array, an output from each the antenna elements in the sub-array can be combined to produce a sub-array output signal. The sub-array output signals are selectively weighted and combined in a fully adaptive process. Subsequently, the system can estimate an angle-of-arrival direction for a signal-of-interest (“SOI”) and at least one signal-not-of-interest (“SNOI”). Based on this estimating step, the system calculates a new set of weighting factors for controlling one or more of the sub-array beams to improve the signal-to-noise plus interference ratio obtained for the SOI in the array output signal.

Abstract: A steerable antenna array (10) includes a plurality of antenna elements (12a-12f) which receive broad band signals and narrow band interfering signals which together form antenna signals. The antenna signals are combined with weighting signals by combining functions (16a-16f) to form a combined signal, which is filtered by a filter function (30) to filter the narrow band signals. The filtered signals are sent to a weight processor (50) which also receives the antenna signals as an input. The processor (50) generates the weighting signals so that interference from the narrow band signals is reduced.

Abstract: A microprocessor reads the information such as directions of arrival about a desired wave and an undesired wave for every terminal station and for every hopping frequency, and their receiving powers, and the like, from a desired wave/undesired wave information inputting unit. On the basis of the information items, the microprocessor calculates the weight values of a transmitting section and a receiving section for every terminal station and every hopping frequency, and stores them in a weight value table. At the time of performing radio communication, the microprocessor reads the weight values of the receiving section and the transmitting section corresponding to every terminal station and every hopping frequency from the weight value table every time the frequency is hopped, and sets them in attenuators, and phase shifters. As a result, the optimum directivity pattern is formed for every hopping frequency, and high-quality communication can be thereby achieved.

Abstract: The invention relates to a beam forming network of an active antenna with deployable sub-arrays. According to the invention, the network receives information on deformation of the relative position of two panels. Establishing the coherence of the signals takes account of this information to restore the received signals. The invention also provides a spacecraft including the above kind of network and further provides a beam forming method. The invention also provides a system including a craft of the above kind and at least one beacon transmitter station.

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 the versatility of 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. Further, this system and technique are not constrained by requiring a priori knowledge of the jamming interference.

Abstract: The present invention reduces the number of tuners required by an adaptive array that reduces interference in the selected channel of the received desired signal with signals present outside the selected channel bandpass, where the adaptive array includes antennas for generating wideband input signals, weights for generating weighted wideband input signals, adder to sum the weighted wideband input signals, bandpass filter to remove signals from the adder output signal outside the bandpass of the selected channel, feedback function to generate the feedback signal from the bandpass filter output signal, a weight calculator for each weight which includes correlating the wideband signal coupled from the antenna with the feedback signal to generate the weight value. The bandpass filter removes the signals outside the selected channel bandpass, and the weights adapt to reduce interference in the selected channel bandpass.

Abstract: A system and method for RF autotracking multiple antennas (preferably located on a spacecraft) to compensate for disturbances experienced by the antennas. The system and method estimate high frequency errors associated with all of the antennas. The high frequency errors may be estimated using a currently selected antenna and a high-pass filter. The high frequency errors may be estimated using a sensor mounted on the spacecraft, such as a gyro or star tracker, or may be estimated using information, such as planned thruster firings, for example, from a spacecraft attitude control system. Alternatively, the high frequency information may be estimated using any combination of data from these sources. Low frequency errors are estimated using measurements from each selected antenna. The algorithm implemented in the present invention explicitly accounts for the frequency content of each disturbance source.

Abstract: To suppress interfering stationary targets in radar source data, a STAP filtering method is used. Filtering coefficients are determined, and filtering of the data takes place, in the frequency domain; the process is therefore limited to a few computing operations per matrix element of the range/Doppler matrix. Since, by means of the STAP filter according to the invention, the optimal filtering characteristics can be implemented, the stationary target suppression also functions in the range of the minor lobes of the antenna. Therefore, data of individual adjacent channels (L/R, left/right) can be processed as well as summation and difference signals (&Sgr;/&Dgr;).

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 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.