Abstract: Process for estimating the correlation matrix of signals of unknown characteristics in an array of N sensors comprising the following steps:

Abstract: An adaptive antenna receiving apparatus includes (a) a plurality of antennas, (b) a plurality of adaptive receivers each of which receives signals received in the antennas, in an adaptive antenna pattern in an order in which the signals arrived at the antennas, (c) a plurality of initial receipt weight calculators each of which calculates an initial antenna pattern for each of the signals, and outputs the thus calculated initial antenna pattern to each of the adaptive receivers, (d) an adder which adds output signals transmitted from each of the adaptive receivers, to one another, and (e) a judge which symbol-judges an output signal transmitted from the adder, and transmits an output signal to each of the adaptive receivers.

Abstract: Signals received by antenna elements are respectively converted to lower frequency signals by the frequency converters. The lower frequency signals are then converted to the digital signals by A/D converters and supplied to a digital signal processing unit. The digital signal processing unit weights the digitized signals on the amplitude and the phase for each signal for optimally controlling the directivity. The weighted signals from the digital signal processing unit are converted to the analog signals by D/A converters and added by an adder. The added signal is then converted by a frequency converter to an original frequency of the received signals by the antenna elements.

Abstract: Calibration signals which were generated in a signal generator 107 for calibration and to which frequency conversion was applied in a radio transmitting section 108 for calibration are made to be power levels in power level variable circuits 109-1 to 109-N so that power levels of calibration signals extracted in a signal processing section 106 for calibration become constant, and are multiplied by signals received at antenna elements 102-1 to 102-N in multiplex circuits 103-1 to 103-N.

Abstract: A method for controlling an adaptive antenna array (50) is provided and includes receiving a plurality of signals, each signal including a series of signal data symbols (42) and signal non-data symbols (38, 40) divided into symbol transmission units with the signal non-data symbols (38, 40) disposed among the signal data symbols (42) in each unit and each signal related to the other signals of the plurality of signals as reflections of an original signal. The method also includes separating the signal non-data symbols (38, 40) from the signal data symbols (42), and comparing the signal non-data symbols (38, 40) to a set of known non-data symbols. The method further includes determining a set of weights according to the comparison of the signal non-data symbols (38, 40) to the set of known non-data symbols, the weights to be combined with the signal data values (42) to limit the effect of interference on the signal data symbols (42).

Abstract: A spread spectrum radio transmission digital mobile communication device having RAKE receiving functions. By adding an arrangement of an adaptive antenna to control directivity of a receiving antenna to the spread spectrum radio transmission digital mobile communication device, it is possible to decrease influence of a co-channel interference wave and influence of a delay wave having a delay time smaller than chip time width in a diffusion signal, as not achievable by RAKE receiving functions.

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: 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: A method and apparatus are provided for determining whether a signal received the main channel (2) of an antenna (1) was incident on the antenna (1) in a direction corresponding to a high gain main lobe. A sidelobe suppression signal is generated from signals received from a other channels at least some of which are derived from elements where output generates the main channel, the signal being categorized as originating from a direction corresponding to the high gain main lobe of the main channel by comparing the value of the signal received on the main channel with that of sidelobe suppression signal.

Abstract: A DSRC car-mounted equipment which prevents, in advance, inconvenience caused by disorder in the antenna unit of the car-mounted equipment.

Abstract: An intermediate-frequency signal is fed to a demodulated-signal processing circuit through a variable gain circuit, an active filter, and a limiter. An RSSI output signal responsive to a received signal level is obtained through a low-pass filter by detecting the output of each stage of the limiter at a detector and by summing the output of the detector at an adder. The linearity of the RSSI output signal responsive to the received signal level is improved by feeding, via a coefficient multiplier to the adder, the control signal of a level detector which detects the control signal of the variable gain circuit, which limits the signal input to the active filter.

Abstract: An adaptive transmission diversity apparatus utilizes a spread spectrum system, detects radiation patterns of direct and indirect waves, which have arrived in a time-shifted manner, by reception radiation pattern controllers. A transmission radiation pattern controller is utilized in accordance with a transmission radiation pattern. The transmission radiation pattern is determined by selecting a pattern from reception radiation patterns obtained by the reception radiation pattern controllers. This can ensure a higher transmission performance.

Abstract: A high capacity broadband base station employs a wideband radio and phased array processing subsystem. This phased array antenna subsystem contains multiple sets or pairs of alternating receive only and transmit/receive elements distributed in a two dimensional spatial array. Each digital wideband radio performs both receive and transmit channel signal processing. In the receive direction, the digital representation of the entire spectrum for each antenna element is divided into channels for the particular waveform of interest. For a 5 MHz PCS GSM, the digital wideband radio separates twenty-four carriers into twenty-four (200 KHz wide) data streams, each of which is representative of a respective channel, and couples each channel to a digital signal processor. In the transmit direction, the radio combines the digital representations of the twenty-four individual channels supplied by the DSP into a single wideband channel for transmission.

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 nulling system (28) for nulling a jamming signal having a multibeam antenna (48), a correlator (72), and antenna pattern calculator (94), a sequential updater (90) and a beamformer (70) is provided. The multibeam antenna (48) includes a plurality of antenna elements (50) and is operable to receive the plurality of signals. The correlator (72) is operable to receive at least one sample signal from one of the antenna elements (50) and a composite signal from the plurality of antenna elements (50). The correlator (72) determines a cross-correlation of the sample signal and the composite signal. The antenna pattern calculator (94) calculates a difference in pattern magnitude of an adapted antenna pattern and a quiescent antenna pattern of the multibeam antenna (48). The sequential updater (90) sequentially calculates a new weight for each of the antenna elements (50) based upon an existing weight of each antenna element (50), the cross-correlation and the difference in pattern magnitude.

Abstract: The present invention provides a spread spectrum radio transmission digital mobile communication device having RAKE receiving functions and capable of decreasing influence of a delay wave having a delay time smaller than chip time width of a diffusion signal.

Abstract: A radar apparatus provided with a sidelobe blanking circuit. The apparatus includes a directive antenna with a main receiver, and an auxiliary antenna with an auxiliary receiver. The apparatus also has a differential antenna with a differential receiver. Comparators compare the outputs of the auxiliary receiver and the differential receiver. Blanking does not occur when the output of the main receiver is larger than both other output signals.

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: 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: Without use of separate auxiliary antennas, adaptive nulling automatically reduces jamming or other interference affecting a radar or IFF system. A primary beam forming network utilizes four-port directional coupler devices, each having an ancillary port which would have been resistively terminated in the absence of the invention. Signals from ancillary ports are coupled to an auxiliary beam forming network to form auxiliary beam patterns which are orthogonal to and track steered main beam patterns. Auxiliary signals are received via the auxiliary beam patterns. Least mean square (LMS) control loops operate on a feedback basis to derive weighted auxiliary signals responsive to jamming signals. The weighted auxiliary signals are combined with the primary received signals (which may be sum and difference signals) in reverse polarity, so as to be additively destructive of the jamming signals. Multiple LMS control loops enable nulling of jamming signals simultaneously in sum and difference channels.

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: 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 CMA-based antenna system is disclosed which shows an improved receiving performance by reducing phase differences in the received signals which have been weighted. The CMA-based antenna system comprises a plurality of antenna, weight circuits, an adder, an error detector and a synthesis controller. The synthesis controller controls the weight circuits so as not only to make the adder output at a preset level but also to cause any differences among the weight circuit outputs not to increase. In order to cope with an error of symbol synchronization and a delayed wave, the CMA-based antenna system may further have a kind of equalizer inserted before the weight circuit in each antenna circuit.

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: 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 method for effecting a wireless exchange of data between a stationary station and transmitter/receivers on board objects, particularly vehicles moving relative to the stationary station. The reception profiles of an antenna array having a plurality of receiving antennas is directed electronically onto an object. The transmitter/receivers on the object transmit, in response to the received signal, an answer signal having the same carrier frequency as the signal received and having a level which is proportional to the level of the signal received. In the antenna array, a transmitting antenna is associated with each receiving antenna, and the transmitting antenna sends out signals having a transmission profile which corresponds to the reception profile of the receiving antenna. The damping factors of transmission profile and reception profile are thereby multiplied by each so that two relatively simple circuits are necessary in order to achieve a desired high side-lobe damping.

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 wideband, wide angle sidelobe cancellation array system is disclosed. The system includes a main array formed of a plurality of regularly spaced elements, and an auxiliary array formed of two auxiliary antenna elements spaced from the outermost elements of the main array a distance equal to one-half the spacing of the main array elements. The received signals from the main array elements are combined to form a main array signal. The contributions from the auxiliary array elements are combined to form an auxiliary array signal. The two array signals have a good amplitude and phase match over a wide frequency and angle range. The main array and auxiliary array signals are then combined to form a system array signal wherein the sidelobe energy in the main array signal has been substantially cancelled. The system can be made an adaptive one by the addition of adaptive RF phase and amplitude weighting to the auxiliary array signal prior to combining with the main array signal.

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: A digital signal processing method and apparatus for beam forming utilizes an N-element phased array antenna (1). For transmit side beam forming of an agile beam to be steered in a direction between three adjacent orthogonal beams three copies of complex envelope samples for the required beam signal are generated, separately weighted in amplitude and phase (4) and fed into an N-part inverse FFT processor (3) via three input ports (7a, 7b and 7c) which correspond to the three adjacent orthogonal beams, and inverse Fast Fourier Transformed therein into the required beam as a weighted combination of the three adjacent orthogonal beams for passage to the elements (2) of the phased array antenna (1).

Abstract: A radar interference circuit which rejects both continuous noise and shorulse interference signals. A plurality of omni-directional antennas are placed around the main directional radar antenna and connected in differing sets to a plurality of canceller means to each of which the main antenna signal is also connected. The canceller means for each set of three Omnis and the main antenna cancels out the white-noise interference received by that group of antennas. The outputs of the plurality of canceller means are then taken in different sets of two each, subtracted and compared to a threshold signal. If one or more comparator outputs are above the threshold, signifying that the antenna pulse signal is being received through the sidelobes of the antenna patterns, the outputs of these comparators will be a one signal and the OR gate, to which the comparator outputs are fed, will provide an output to blank the radar.

Abstract: A sidelobe canceler includes a main antenna, an array of sub-antennas, a subtractor having a first input connected to the main antenna, a main-array processor and M sub-array processors. The main-array processor multiplies the outputs of the sub-antennas with weight coefficients using correlations between the sub-antenna outputs and the subtractor output and combines the multiplied signals into a signal, which is coupled to the second input of the subtractor. The signal-to-noise ratio of the subtractor output is maximized by an adaptive matched filter. Each sub-array processor multiplies the sub-antenna outputs with weight coefficients using correlations between the sub-antenna outputs and a decision signal. The multiplied signals are summed to produce an output of each sub-array processor, which is combined with the outputs of the other sub-array processors into a first diversity-combined signal, the latter being combined with the matched filter output to produce a second diversity-combined signal.

Abstract: The disclosure relates to methods and apparatus for facilitating the accurate measurement of Doppler frequency shift induced on a one-way-propagated signal wave either by deliberate on-platform controlled actual or simulated motion of a receiving antenna means, or by relative motion between transmitting and receiving platforms, or by both. The methods and apparatus of this invention are directed to the suppression of identifiable components of a composite modulation process on a sinusoidal carrier, for the purpose of retaining, for separate detection, measurement or transmission, the result of any of the aforementioned frequency-shift inducing processes.

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: An improvement in monopulse radar achieves nulling of multiple mainlobe jammers while maintaining the angle measurement accuracy of the monopulse ratio by using multiple simultaneous beams, thereby obtaining the additional degrees of freedom necessary for cancelling more than one mainlobe jammer (MLJ). The beams are placed one null beamwidth apart in order to maintain orthogonality. The MLJs are nulled in the orthogonal direction of the angle estimate giving undistorted monopulse ratios.

Abstract: In a sidelobe canceller, a main channel multiplier (11) operates on the baseband output signal of a main antenna (10) with a weight signal to produce a weighted main channel signal. The baseband output signals of auxiliary antennas (16.sub.1 .about.16.sub.n) are adaptively weighted so that the auxiliary antennas have a first directivity pattern (44) whose main lobe oriented toward an undesired signal and summed together to produce a first sum signal (y.sub.s), and further adaptively weighted so that the auxiliary antennas have a second directivity pattern (45) whose main lobe is oriented toward a desired signal, and summed together to produce a second sum signal (y.sub.d). The second sum signal (y.sub.d) is summed with the weighted main channel signal to produce a diversity combined signal (y.sub.c), and the first sum signal (y.sub.s) is subtracted from the diversity combined signal (y.sub.c) to produce a sidelobe cancelled signal (y.sub.z).

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 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: Apparatus for electronically steering a null in a total radiation-reception pattern provided by a set of angularly disposed (preferably substantially-orthogonally-positioned RF) antennae, uses: first and second N-bit binary attenuator subsystems for modifying the amplitude of a signal provided by an associated one of the pair of antennae, responsive to an associated one of first and second control data signals; a set of look-up tables, receiving null-angle input data, provide the first and second signals as the sine and cosine, respectively, of the input null-angle; and the output of the first and second attenuator means are then combined to provide an output signal in which contributions arriving at the set of antennae substantially at the null angle are substantially reduced. The signal combiner may include at least one polarity reversal circuit, possibly including a transformer and/or switch means, to accommodate nulling to all four quadrants of a full circular response pattern.