Abstract: A direction to the location of a mobile terminal from an antenna array is determined. A sequence of symbols from each antenna 2 in the array, is stored. The sequence contains a known training sequence. The sequence is space processed iteratively so as to produce the effect of the array having a major lobe in its polar diagram at a plurality of different successive directions. A set of crosscorrelation metrics is derived by calculating a crosscorrelation metric for each direction between the combined signals and the known training sequence. The ratio is calculated of the crosscorrelation metric for each direction to the power of the combined signals for that direction to produce a set of direction metrics. A direction is ascribed to the mobile terminal using the direction metrics to determine which direction is most likely.

Abstract: A method and system for adaptive signal processing for an antenna array reduces the requisite computations for executing an adaptive algorithm that combines or digitally filters baseband receive signals. The system receives uplink electromagnetic signals from a phased array and uplink electromagnetic signals from a diversity array during the reception of a desired electromagnetic signal transmitted by a desired mobile station. The uplink signals are converted into baseband signals for digital signal processing. The baseband signals are observable as a series of successive time slots. The system determines uplink coarse combining weights associated with the uplink baseband signals of the phased array and downlink coarse combining weights associated with the downlink baseband signals of the phased array. The baseband uplink signals are summed into as few as one resultant baseband signal during or after application of the coarse combining weights to the baseband uplink signals.

Abstract: The present invention concerns calibration of a group antenna system (11) with a number of radiation elements (X1, . . . , XN) and a number of controllable transmitters (T1, . . . , TN), in which the transmitters at the reception of an input signal transmit output signals for feeding the radiation elements. The calibration is done to be able to obtain a time varying antenna diagram at transmission and should be able to perform under operation without interrupting the normal operation of the group antenna system (11). The group antenna system comprises a control system for automatically correcting the control of the transmitters (T1, . . . , TN) for error deviations thereof. The group antenna system (11) comprises means (37) for generating a sum signal corresponding to the sum of the output signals. The control system generates error signals, giving information about the error deviations, employing the sum signal, the input signal and the complex amplifications varying with time for the transmitters.

Abstract: A method and apparatus for apparatus for controlling communications between a mobile cellular telephone and a cell of a cellular telephone network. The apparatus comprises a serving transceiver for transmitting and receiving communications between the cell and the mobile cellular telephone, a scanner, coupled to an antenna, for selectably scanning the communication channels to measure a characteristic of the signal transmitted from the mobile telephone, and a controller, coupled to the scanner and the serving transceiver, for commanding the antenna based on the measured signal characteristic.

Abstract: Received signal provided via plural antennas 101 are memorized in memory 102. First weight controller 103 calculates the first weights by which the received signals are weighted, and second weight controller 104 calculates the second weights using the received signals. Multipliers 107 and 108 multiply the memorized received signals by the first weights, while multiply the memorized received signals by the second weights when a channel quality of radio signals deteriorates due to a change of the radio signal's direction of arrival Adder 109 synthesizes the multiplication results. Propagation path distortion compensator 110 estimates a deterioration of the channel quality using synthesis result to compensate.

Abstract: Weighting coefficients for a phased array antenna are iteratively refined to optimal values by a ‘bootstrapped’ process that starts with a coarse set of weighting coefficients, to which received signals are subjected, to produce a first set of signal estimates. These estimates and the received signals are iteratively processed a prescribed number of times to refine the weighting coefficients, such that the gain and/or nulls of antenna's directivity pattern will maximize the signal to noise ratio. Such improved functionality is particularly useful in association with the phased array antenna of a base station of a time division multiple access (TDMA) cellular communication system, where it is necessary to cancel interference from co-channel users located in cells adjacent to the cell containing a desired user and the base station.

Abstract: Methods are disclosed for receiving GPS signals in the presence of multiple interference signals. The methods feature the orthogonal projection of sub-optimal weight vectors onto sets of orthonormal basis vectors. They facilitate the use of single-port reception techniques in which power is monitored only at a single GPS array output port regardless of the number of array elements. The methods do not require prior knowledge of interference signal structure and their use of uncoupled orthonormal basis vectors facilitates the simultaneous adjustment of array weights and rapid convergence to an optimal set of weights.

Abstract: An antenna array system combines the antenna signals from separate antennas using at least one delay in the RF path of an antenna. In certain embodiments, the antenna array system combines the antenna signals in the Radio Frequency (RF) domain before analog-to-digital (A/D) conversion, thereby reducing the amount of hardware required when compared to antenna array systems where the antenna signals are combined digitally. In doing so, signals from antennas are combined with signals from a plurality of antennas to determine if they improve signal quality. Only signals determined to improve signal quality are maintained as active. In accordance with other aspects, the antenna system selects parameter settings for the antenna array to provide enhanced performance.

Abstract: A signal processing apparatus for minimizing interference and for reducing effects of noise by controlling beam patterns of a telecommunication system having an array antenna, comprising: a means for computing a residue vector, by using a signal vector provided from said array antenna at each snapshot, a final array output signal of said telecommunication system at the last previous snapshot and a value of a gain vector of the present snapshot, and for outputting said residue vector; a means for synthesizing a scalar value, which is needed to generate a search direction vector, from said residue vector; a means for producing said search direction vector, by using said residue vector and said scalar value; a means for producing an adaptive gain, by using said signal vector, said search direction vector, said final array output signal of said telecommunication system at the last previous snapshot and the value of said gain vector of the present snapshot; and a means for updating said gain vector, by using said

Abstract: An adaptive antenna includes a buffer for storing sample data obtained by sampling a receive signal, an information storage part for storing a plurality of sets of coefficients, an evaluation part for calculating an evaluation value of the result obtained by the coefficient and the sample data, a selection part for selecting two or more sets of coefficients in order of decreasing evaluation, an exchanging part for exchanging a part of coefficients between the selected sets of coefficients to generate a new set of coefficients, a changing part for changing a part of coefficients of the selected sets with random numbers to generate a new sets of coefficients, a reproduction part for reproducing the selected sets of coefficients as they are, and a determination part for outputting the result obtained by the set of coefficients with the highest evaluation value after the information storage part, the evaluation part, the selection part, the exchanging part, the changing part, and the reproduction part repeats res

Abstract: A group antenna has the weighting factors of the individual antenna elements and a forward and backward filter adapted based upon a decision circuit at the input of which the output signals of the two filters are subtracted one from the other. A Maximum Like Sequence Estimator receives the output of the forward filter directly while the decision feedback process is shut down for detection of subscriber data whereas the MLSE operates in parallel with the decision feedback process for continuous adaptation of the weighting factors.

Abstract: According to the present invention, there is provided an adaptive array antenna including a plurality of antenna elements for receiving radio waves transmitted via multi-carrier waves, weighting means for weighting received signals received by the plurality of antenna elements with weight amounts for the respective antenna elements, adding means for adding up weighted signals by the weighting means, extracting means for extracting particular carrier components from the received signals received by the plurality of antenna elements, and weight setting means for setting the weight amounts for the respective antenna elements to the weighting means on the basis of the particular carrier components extracted by the extracting means.

Abstract: An array antenna system of a wireless base station in CDMA mobile communications combines signals, which have been received by a plurality of antenna elements of an array antenna, upon subjecting the signals to amplitude and phase-rotation control, and despreads the combined signal. A searcher has matched filters which apply correlation operations to output signals from respective antenna elements to thereby calculate correlation signals that are correlated with a signal transmitted from a mobile station of interest. An adaptive weight calculating unit calculates adaptive weights for obtaining in-phase correlation signals from the respective antenna outputs. A beam former multiplies, by the adaptive weights, output signals from the corresponding antenna elements and combines the resulting products to output a combined signal. The combined signal is found for each path of multipaths and is input to a Rake receiver, which proceeds to identify data.

Abstract: The invention relates to a method and to apparatus for determining incident received power or energy or other technical measurement values of at least one signal in at least in one predeterminable direction of observation, further to receiving equipment. The method of the invention allows unambiguously determining the received power or energy of a signal incident in a predeterminable direction of observation even when additional signals are simultaneously incident from other directions. The method of the invention can be implemented using a sensor or antenna array of unfilled aperture.

Abstract: Transmit adaptive phased array antenna system and receive adaptive phased array antenna system are disclosed which include a transmitter unit; a power divider unit which is connected to the transmitter unit, and when transmitting, divides computed weights; a receiver unit; an array antenna unit wherein multiple basic elements of antenna are spatially arrayed; a power feeder unit which, at the time of receiving, receives receive signal of the array antenna unit and changes amplitude and phase of the receive signal according to another control signal, and at the time of transmitting, receives divided signal from the power divider unit; a power combiner unit which sums receive signals, which are received from the power feeder unit, by using weights; an amplitude detector unit which checks the amplitude of the signals which are received from the power combiner unit, and transmits them to the receiver unit; a beam control unit which receives a portion of the amplitude of summed signals from the amplitude detector,

Abstract: Communications equipment for use in a combat vehicle with at least one transmitting antenna and at least one receiving antenna and with more communications terminals than transmitting antennas or receiving antennas. Control logic accordingly contains a signal-path matrix by which any communications terminal can be connected, depending on its operating state "transmit" or "receive", either to a transmitting antenna along a high-frequency transmission path that includes a power adder or to the receiving antenna along a high-frequency reception path that includes a level distributor.

Abstract: This invention provides a design technique of the array antenna, and a telecommunication system and method utilizing the array antenna for enhancing the communication quality and increasing the communication capacity by reducing the interfering signals and noises with the nice beam pattern. And, the design technique of the array antenna, and the telecommunication system and method utilizing the array antenna introduce a simplified computational technique for generating a nice beam pattern having its maximum gain along the direction of the wanted signal and maintaining the gain toward the direction of the interfering signals in as low a level as possible.

Abstract: This antenna array for base station for radiocommunication with mobiles comprises N first sensors, N being an integer greater than 2, arranged in such a way that the array exhibits substantially no ambiguity; an (N+1).sup.th sensor placed or contrived in such a way as to receive signals which are decorrelated from the previous ones; and a module for processing the signals received, making it possible to locate, in an explicit or implicit manner, a transmitting mobile from the signals received by the N sensors alone, and to combine these signals and the signals received by the (N+1).sup.th sensor so as to improve reception by effecting spatial or spatio-temporal diversity.

Abstract: The present invention provides a method, device, base station and subscriber unit for combining a plurality of antenna output signals to provide a combined data signal in a communication system where the antennas receive at least one user signal and where the at least one user signal contains pilot symbols and data symbols. The method includes the steps of: forming, in at least one communications receiver, a plurality of weighted antenna output signals, one for each antenna of a plurality of antennas, based on at least two covariance matrices and at least two steering vectors determined from the pilot symbols; and combining the weighted antenna output signals from the plurality of antennas to form the combined data signal.

Abstract: A complex multiplying section multiplies a receiving signal by a complex weighting factor of a weighting factor controlling section. The output is added by an adding circuit, and decoded by a decoding circuit so as to obtain a received signal. The weighting factor of the weighting factor controlling section is set using only the weighting factor calculated by a synchronous burst having a different unique word pattern. On one hand, it is assumed that an interference station having the same unique word pattern exists. Then, a decision feedback adaptive array antenna receiving circuit 400, which does not update the weighting factor using the unique word pattern, performs a signal reception. On the other hand, it is assumed that no interference station having the same unique word pattern exists. Then, the conventional decision feedback adaptive array antenna receiving circuit 500, which updates the weighting factor using the unique word pattern, performs a signal reception.

Abstract: A method of reducing jamming in a global positioning system (GPS) satellite receiving system includes the steps of: a) selecting an initial weight value corresponding to each antenna element; b) selecting a weight adjustment scheme for adjusting the weights; c) measuring a power output from the antenna array; d) obtaining navigational data representing the orientation of the array; e) calculating for a gain of the antenna array corresponding each of the GPS satellites, using the navigational data to provide an indication of the orientation of the array relative to each GPS satellite; f) estimating a power level of a received signal corresponding to each GPS satellite; g) solving for the signal to noise ratio for each GPS satellite, using the estimated power level corresponding to each GPS satellite; h) iteratively and continuously adjusting the weights to obtain a greatest value of the signal to noise ratio; and i) continuously repeating steps (c) through (h).

Abstract: A system and method for RF autotracking multiple antennas to compensate for disturbances experienced by the antennas. The system and method uses two control algorithms implemented in fast and slow controllers and sums the result for each antenna that is tracked. One (fast) control algorithm corrects for rapid, common mode disturbances such as spacecraft motion disturbances, while the other (slow) control algorithm corrects for slower disturbances, such as thermal distortion, that do not affect all antennas in the same manner.

Abstract: Adaptive arrays with an automatic adaptive loop gain control to reduce the degradation in performance in reducing the effects of multipath and interference in communications receivers when the gain of any of the adaptive loops change with a change in the average level of any of the input signals of the adaptive array. As the input level of any of the input signals of the adaptive array changes, the associated adaptive loop gain control(s) reduces the change in the adaptive loop gain from the optimum gain value to improve adaptive array performance. When signal conditions and/or component configurations cause the levels of the input signals to be different from input to input of the adaptive array, the performance of the adaptive array is improved further by also equalizing the input signals.

Abstract: A phased array spread spectrum system for maximizing signal strength of a spread-spectrum signal with multipath through the use of receiving means, delaying means, combining means, despreading means, generating means, storing means and comparing means. The receiving means receives a plurality of spread-spectrum signals and a plurality of phased versions of the plurality of spread-spectrum signals. The delaying means delays the received plurality of spread-spectrum signals with respect to the plurality of phased versions of the plurality of spread-spectrum signals by a plurality of delays. The combining means combines the delayed spread-spectrum signals and the plurality of phased versions of the plurality of spread-spectrum signals as a plurality of combined signals. The despreading means despreads the plurality of combined signals as a plurality of despread signals. The generating means generates a plurality of magnitude values from the plurality of despread signals.

Abstract: RF signal nulling and loss of RF lock (i.e., loss of a communications or command link) is resolved by changing the phase of signals derived from first and second (+Z and -Z) antennas so that they add in phase instead of canceling. This is accomplished automatically by using a computer or processor to measure the RF signal level output by a receiver and change the phase of the incoming signal using a phase shifter to achieve the highest level. A squelch circuit in the receiver is used to determine the maximum obtainable RF signal level. The squelch level is compared in a computer to a threshold when the system looks for a higher squelch level. The phase of the phase shifter is changed using a computer to maximize the received signal level. A feedback loop from the receiver through the computer to the phase shifter provides a path to shift the phase of the incoming RF signal in one of the paths so the respective signals add instead of cancel, which eliminates the signal nulling problem.

Abstract: A method of stabilizing the action of a phased array antenna system in which the amplitudes and phases of signals applied to, or produced by, elements of the antenna are monitored, differences are detected and suitable weighting factors are determined and applied to remove the differences between the amplitudes and phases of the said signals.Transmitting and receiving antenna systems are described.

Abstract: A digital beam forming system includes an array of computing units (60-76) for weighting incoming signals and a plurality of summing processors (80-84) for generating output signals that represent weighted sums corresponding to rows within the array. The digital beam forming system can be incorporated in either a transmitter or receiver used in a radio frequency communications system.

Abstract: A digital beamforming network for transmitting a first number of digital information signal using a second number of antenna array elements is disclosed. Assemblers are used for assembling one information bit selected from each of the information signals into a bit vector. Digital processors have an input for the bit vector and a number of outputs equal to the second number of antenna elements and process the bit vector. Finally, modulation waveform generators coupled to each of the second number of outputs generate a signal for transmission by each antenna element.

Abstract: A method of controlling an array antenna having a plurality of antenna elements for providing antenna output signals by receiving TDMA burst signals. The method includes a step of estimating a DOA of incident signal based upon the antenna output signals, a step of calculating weights with reference to the estimated DOA, a step of multiplying the antenna output signals by the calculated weights, respectively, and a step of summing the multiplied antenna output signals. The estimating step includes a first step of calculating a phase difference between the output signals of the two antenna elements during burst, a second step of calculating a phase difference between the output signals of the two antenna elements during an interval of bursts, and a third step of calculating a difference between the calculated phase differences.

Abstract: A communication interference detection method determines the direction toward a source of interference by combining interference signals from a sweeping directional antenna with communication signals from an omni antenna while measuring and recording power, frequency spectra, and interference-to-signal ratio over a wide range of conditions using a spectrum analyzer and power meter and communication receivers. The method can be used in the field to locate interfering sources which might interference with the reception of communication signals such as Global Position System (GPS) communication signals.

Abstract: The method consists in estimating the matrix of correlation R.sub.XX of the signals received on a set of N reception sensors, computing the reverse correlation matrix R.sub.XX.sup.-n, computing vectors of intercorrelation r.sub.Xd between the signals received on the set of the N sensors and a known replica signal d(k), computing a criterion of synchronization in calculating the products of the conjugate, transposed intercorrection vectors R.sub.XX.sup.-n and of the matrix of the intercorrelation vector r.sub.Xdi and comparing the value of the criterion obtained with a determined threshold value 1 to place the synchronization on the sample for which the value of the criteria exceeds the threshold value .eta.. To estimate the Doppler shift the synchronization sequence is subdivided into a determined number of sections of symbols to carry out fast Fourier transform computations on determined intercorrelation vectors in each section.

Abstract: An adaptive transmitting antenna includes an array of antenna elements having respective weighing coefficients to respectively transmit components of a transmit signal which reduces locally reflective multipath signals received by the transmitting antenna to sample respective reflective components which are summed and cross correlated to a time delayed transmit signal to produce a correlated output indicative of the reflective signal strength. The correlated output is minimized by adjusting the weighing coefficients so that the transmit signal has reduced multipath distortions. The adaptive technique is well suited for mobile telephone transmitters moving about objects tending to reflect and distort transmitted signals.

Abstract: A high gain Cassegrain reflector antenna system is disclosed for use in a RF signal receiving application. In one embodiment of the invention the antenna is a single parabolic reflector antenna having a plurality of feeds, while in another embodiment the RF signal is received by a number of parabolic reflector antennas. Each received RF signal component is separately amplified to produce corresponding individual amplified signals which are then summed to produce a summation signal. A phase difference between the summation signal and each individual amplified signal is determined, and each individual amplified signal is then phase adjusted until it is in a substantially coherent phase relationship with the summation signal. The phase adjustment compensates for phase displacement errors occurring due to, by example, an effective sector displacement error of a primary reflector of the Cassegrain antenna assembly.

Abstract: A beam electronically steers, in real time, a multielement sensor array at radio frequencies. A sensor array is configured in one embodiment with orthogonal loops and orthogonal dipole elements. Each loop and dipole combination generates a polarized output signal which is routed, via a connection matrix, to an equal number of signal splitters. The resulting modal patterns are then routed to networks having quad hybrids and digitally user-controllable vector modulators. The signals outputted from the quad hybrids and the vector modulators of each of the networks are inputted to separate combiners. The signals outputted from the separate combiners of the networks are then recombined in combiners. The signals outputted from these combiners define the azimuth around the Z-axis, the elevation around the Y-axis, and the elevation around the X-axis, respectively.

Abstract: A phase array spread spectrum system for maximizing signal strength of a spread-spectrum signal with multipath through the use of receiving means, delaying means, combining means, despreading means, generating means, storing means and comparing means. The receiving means receives a plurality of spread-spectrum signals and a plurality of phased versions of the plurality of spread-spectrum signals. The delaying means delays the received plurality of spread-spectrum signals with respect to the plurality of phased versions of the plurality of spread-spectrum signals by a plurality of delays. The combining means combines the delayed spread-spectrum signals and the plurality of phased versions of the plurality of spread-spectrum signals as a plurality of combined signals. The despreading means despreads the plurality of combined signals as a plurality of despread signals. The generating means generates a plurality of magnitude values from the plurality of despread signals.

Abstract: A phased array spread spectrum system for maximizing signal strength of a spread-spectrum signal with multipath through the use of receiving means, delaying means, combining means, despreading means, generating means, storing means and comparing means. The receiving means receives a plurality of spread-spectrum signals and a plurality of phased versions of the plurality of spread-spectrum signals. The delaying means delays the received plurality of spread-spectrum signals with respect to the plurality of phased versions of the plurality of spread-spectrum signals by a plurality of delays. The combining means combines the delayed spread-spectrum signals and the plurality of phased versions of the plurality of spread-spectrum signals as a plurality of combined signals. The despreading means despreads the plurality of combined signals as a plurality of despread signals. The generating means generates a plurality of magnitude values from the plurality of despread signals.

Abstract: Adaptive arrays with an adaptive loop gain control to reduce the degradation in performance in reducing the effects of multipath and interference in communications receivers when the gain of the adaptive loops change with a change in the input signal level of the adaptive array. As the input signal level to the adaptive array changes, the adaptive loop gain control reduces the change in the adaptive loop gain to improve adaptive array performance.

Abstract: An adaptive nulling communication system for nulling undesired signals from communication signals in multiple separate and distinct coverage areas is disclosed. The adaptive nulling communication system includes a phased array antenna having multiple receiving elements to form a single aperture for receiving multiple signals. A first set of beam forming networks coupled to the phased array antenna forms the multiple separate and distinct coverage areas. A distribution network coupled to the first set of beam forming networks distributes the signals received from these coverage areas. A nulling processor having a second beam forming network coupled to the distribution network weights and adjusts the second beam forming network in response to the undesired signals to null these undesired signals from the communication signals.

Abstract: HF aerials for ship-shore communications consist of spaced dipole arrays. By appropriate adaptive phasing very high gain HF aerials are formed. On transmission a feedback signal is required from the receiver, otherwise similar algorithms are used to control the beamforming. A random phase algorithm has been devised for the phases applied to the array aerials, operating in four tranches of 100 iteration steps with progressively reduced maximum phase variation. The initial step has a phase variation in the range .+-.180.degree.. The algorithm has the advantage that there is a high probability that a relatively high gain beam will be immediately formed in the required direction and thus the system can quickly settle towards a direction where the signal is weak. When in the transmit mode the receiver returns a signal to the transmitter giving the step number of the random phases which gives the maximum received signal.

Abstract: The invention relates to apparatus for reducing the masking effect in the doppler frequency domain of wind sheared clutter upon the radar returns of moving targets. The invention consists in forming two beams from the elements of a radar antenna array by means of adjustable complex weights which are then summed. One of the two beams is then delayed by a predetermined amount and added algebraically to the other beam to form a composite beam containing a narrow trough-like depression in beam angle/doppler frequency space. Means are then provided for adjusting the weights to bring coincidence between the depression and the clutter to cause attenuation of the clutter with a minimum reduction in the usable doppler frequency domain.

Abstract: A method and apparatus are provided for filtering noise from a plurality of input signals in a sensor system. One first main input signal and several first auxiliary input signals are obtained and interior weights corresponding to the first main and auxiliary signals are determined. Thereafter, equivalent linear weights corresponding to the interior weights are determined and the equivalent linear weights are applied to second main and auxiliary input signals to filter the second main and auxiliary signals and produce one final output signal. Alternatively, the first input signals can be a subset of the second input signals such that a large set of input signals can be filtered by calculating weighting factors from a subset thereof.

Abstract: A system for automatically forming a receive beam being positioned in the direction of a corresponding incoming signal, the system having a known signal corresponding to the incoming signal. The system comprises a plurality, M, of channels, each of the channels collecting the incoming signal and generating a plurality, L, of incoming complex data samples for the incoming signal and a plurality, L, of known complex data samples for the known signal. The system also includes severaly digital beamforming means for forming the receive beam.

Abstract: A phased array spread spectrum system for maximizing signal strength of a spread-spectrum signal with multipath. A received spread-spectrum signal is delayed with respect to a phased version of the spread-spectrum signal. The delayed spread-spectrum signal is combined with the phased version of the spread-spectrum signal. A magnitude value of the combined signal is compared with a previous-magnitude value. The delay is adjusted in response to the comparison.

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: An apparatus and method of using spatial nulling in antenna electronics to protect against interference signals. Nulling is achieved by computing and adjusting the computed complex weights values of "n" channels through the use of dithering of interfering signals of having power levels thereby allowing nulling of "n" minus one number of interfering signal. sources.

Abstract: A system for cancelling jammer signals entering the mainlobe of a monopulse adar and providing target locations with respect to the jammer position comprising for a sequential lobing embodiment: measuring the angular position of the jammer in the radar's mainlobe via the use of monopulse sum and difference signals, pointing the radar antenna so that the jammer is positioned within the 3 dB points of the mainlobe of the monopulse antenna, converting the sum and difference echo signals received with the antenna in this position from the next radar transmission into a second set sum and difference signals, applying this second set of sum and second set of difference signals to the inputs of an adaptive canceller to cancel the jamming signal therein and storing these signals in time sequential order, changing the orientation of the radar antenna by a small arbitrary elevation angle, converting the sum and difference echo signals received with the antenna in this new position from a third radar transmission into a

Abstract: A system for processing modulated signals received, together with at least one interference signal, by an array of antenna elements in a communications receiver. The method of the invention includes demodulating the received signals, and processing the demodulated signals to produce an output signal that is substantially free of any interference signals, while at the same time effectively steering the antenna pattern produced by the array of elements, to move any spurious nulls in the pattern away from a source of information signals. This results in avoidance of any cycle slipping problems that might otherwise arise in receiver tracking control loops, and has the added benefit of significantly improving performance as measured by the signal-to-noise ratio.

Abstract: A beamformer for a main antenna and a plurality of auxiliary antennas converts the main and each of the auxiliary signals to digital form. Each of the real and auxiliary digital signals is applied to a pair of real multipliers, in which multiplication by beamforming weights is performed, to produce one weighted real main signal, one weighted imaginary main signal, and a plurality of weighted real and weighted imaginary auxiliary signals. The weighted real main and auxiliary signals are summed together by a cascade of summers, and the weighted imaginary main and auxiliary signals are likewise summed together by another summed cascade. A digital product detector is connected to the output of each summer cascade. The first digital product detector produces in-phase and quadrature components of real detected signals, and the second digital product detector produces in-phase and quadrature components of imaginary detected signals.

Abstract: An interference signal suppression system and method that suppresses coherent jamming signals. The system comprises first and second receiving antennas that are physically separated from each other to generate non-coherent received signals of interest. The antennas are positioned to receive communication signals that are jammed with coherent energy. The separation distance is typically 40 to 50 wavelengths of the non-coherent scattered wave radio frequency signals. Phase and amplitude adjustment circuitry is provided that alters the phase and amplitude of the received signals such that the coherent received signals are balanced and out-of-phase. These signal are then summed in a summing circuit and the output of this circuit generates signals wherein the coherent signals are nulled and the non-coherent signals are detectable. The signal suppression system and method is independent of the direction of arrival of the coherent signals, which overcomes limitations of conventional techniques.

Abstract: An adaptive array antenna having a plurality of antenna elements (1-1 through 1-N), related weight circuits (4-1 through 4-N) for weighting amplitude and phase of receive signal by each antenna element, and a combiner (5) for combining weighed signals, has a plurality of antenna beams at the same time by determining weights of said weight circuits, so that a plurality of receive signals due to multipath transmission are received for obtaining high receive level while avoiding multipath interference.