Abstract: Disclosed are various embodiments relating to a method and device for estimating the angle of a base station transmission beam by calculating the time difference between reception signals acquired through simultaneous beam sweeping to multiple antenna arrays.

Abstract: An electronic device (200,300) comprising an antenna arrangement with first and second antenna groups with first (122, 142) and a second (124, 144) radiation elements. The first and second radiation elements in each group have first and second respective polarizations and gain, and said groups also comprise a beam forming network (126, 146) connected to the radiation elements of the group and to an output selector (150). The beam forming network (126, 146) of each antenna group uses the radiation elements (122, 124; 142, 144) in the group to create a radiation pattern (127, 147) with a polarization which is a composite of the first and second polarizations of the elements in the group, so that a first (127) and a second (147) radiation pattern of composite polarization is created. The output selector (150) selects or combines signals received by the two antenna groups as its output.

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 base transceiver station (BTS) identifies the number of currently connected antenna units by receiving a signal to which 1 is added in each antenna unit via a signal line (16) connecting the antenna units (AU1 to AUn) in series. The target output power of each antenna unit, which is obtained by dividing the total target output power of the antenna units by the number of currently connected antenna units, is passed to each antenna unit via a signal line (14) connecting the antenna units in series. Each antenna unit controls the gain of a variable gain amplifier so that its output power becomes equal to the target output power.

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 system for receiving a satellite digital radio signal, the system comprising: a repeater having a unibody housing and an antenna disposed within the housing, the antenna being configured for receiving the satellite digital radio signal; a repeater circuit for receiving the satellite digital radio signal of the antenna, the repeater circuit being configured to condition and re-transmit the satellite digital radio signal as a first signal containing audio data capable of being transmitted through electrical wiring; a satellite digital radio signal receiver having a receiver circuit being configured to receive the first signal; and wherein the receiver circuit receives the first signal from a power cable of the satellite digital radio signal receiver.

Abstract: A wireless communication system, and method using multiple antennas, includes a base station that applies predetermined weight vectors to multi-user signals and transmits the multi-user signals through a plurality of transmission antennas, and a plurality of mobile stations that receive and process the multi-user signals, wherein each mobile station includes a signal reception unit that processes the multi-user signals, and a feedback signal generation unit that estimates channel characteristics, over which the multi-user signals have been transmitted, from the multi-user signals, classifies a plurality of weight vectors to be applied to the estimated channel characteristics into a plurality of sets such that vectors orthogonal to one another are classified into a single set, selects a set maximizing a transmission capacity from among the classified sets, and feeds back weight indexes of weight vectors included in the selected set and weighted channel information to the base station.

Abstract: A smart antenna apparatus including a receiving system, one or more beam analysis modules, a control channel monitoring module, a processing system, and a receiving beam switch is provided. The receiving system is operable to receive a plurality of uplink beams, each including traffic signals transmitted by a mobile station. The beam analysis modules are operable to analyze the uplink beams to determine one or more characteristics of each uplink beam. The control channel monitoring module is operable to monitor control channel signals being communicated from a base station transceiver. The control channel signals include synchronization signals. The processing system is operable to synchronize the smart antenna apparatus with the base station transceiver using the synchronization signals received by the control channel monitoring module.

Abstract: Methods and systems consistent with this invention receive a plurality of transmitted signals in a receiver having a plurality of receive elements, wherein each transmitted signal has a different spatial location. Such methods and systems receive the plurality of transmitted signals at the plurality of receive elements to form a plurality of receive element signals, form a combined signal derived from the plurality of receive element signals, and detect each of the plurality of transmitted signals from the combined signal by its different spatial location. To achieve this, methods and systems consistent with this invention generate a plurality of arbitrary phase modulation signals, and phase modulate each of the plurality of receive element signals with a different one of the phase modulation signals to form a plurality of phase modulated signals.

Abstract: A cosite interference rejection system allows cancellation of large interfering signals with an optical cancellation subsystem. The rejection system includes an interference subsystem coupled to a transmit system, where the interference subsystem weights a sampled transmit signal based on a feedback signal such that the weighted signal is out of phase with the sampled transmit signal. The optical cancellation subsystem is coupled to the interference subsystem and a receive antenna. The optical cancellation subsystem converts an optical signal into a desired receive signal based on an interfering coupled signal and the weighted signal. The weighted signal is therefore used to drive the optical cancellation subsystem. The rejection system further includes a feedback loop for providing the feedback signal to the interference subsystem based on the desired receive signal.

Abstract: The invention concerns 2-oxo-1-pyrrolidine derivatives and a process for preparing them and their uses. The invention also concerns a process for preparing ?-ethyl-2-oxo-1-pyrrolidine acetamide derivatives from unsaturated 2-oxo-1-pyrrolidine derivatives. Particularly the invention concerns novel intermediates and their use in methods for the preparation of S-?-ethyl-2oxo-1-pyrrolidine acetamide.

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: With the object of accurately reproducing, by means of a small-scale circuit, differences in propagation delay at antennas of received signals that are received as input by way of each of a plurality of receivers, frequency data generator 6 supplies frequency data that contain a frequency component that is synchronized in common to the plurality of receivers 2-1 to 2-n. At receiver 2-n, local oscillation signal generator 3-n, which is represented by a D/A converter, generates a local oscillation signal from frequency data that have been synchronized in common. The passing phase of a received signal that is outputted from antenna 1-n by way of receiver 1-n is thus fixed, and as a result, the phase difference of received signals that are received by DSP 8 by way of the plurality of receivers 2-1 to 2-n becomes the propagation delay difference of the received signals.

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 method for reducing interference in a mobile network in which a node A proposes a wireless link with node B. The method includes: (a) determining an angle between an incoming link from a node C to node B and the proposed node A to node B link, wherein the incoming link and the proposed link utilize the same frequency; (b) utilizing a nominal center of a beam of the proposed link, estimate an effective gain at node B to admit interference from the direction of node A into the incoming link from node C; (c) estimating a carrier intensity arriving at node B from node C; (d) determining a ratio of arriving node C to node B carrier to potential interference from the proposed node A to node B link; and (e) conditioning establishment of the proposed node A to node B link upon the determined ratio.

Abstract: A signal detector is provided in which complex samples of a received signal are multiplied by data representative of a hypothesis, and the resulting product data is coherently integrated over a desired duration to provide correlation data representative of the level of correlation between the hypothesis and the signal. In one embodiment, the signal detector is part of a GPS receiver.

Abstract: The present invention relates to an adaptive algorithm and device for the same, for calculating a weight vector to be applied to an adaptive array antenna system, suggesting an adaptive algorithm suitable for calculating an autocovariance matrix of signal vectors of signals received from antennas before despreading in a known channel code, and an autocovariance matrix of signal vectors of signals received from antennas after being despread in the known channel code. Particularly, the calculation is carried out with the autocovariance matrix of the signal vector before the despread divided into diagonal components and non-diagonal components.

Abstract: Methods and systems consistent with this invention receive a plurality of transmitted signals in a receiver having a plurality of receive elements, wherein each transmitted signal has a different spatial location. Such methods and systems receive the plurality of transmitted signals at the plurality of receive elements to form a plurality of receive element signals, form a combined signal derived from the plurality of receive element signals, and detect each of the plurality of transmitted signals from the combined signal by its different spatial location. To achieve this, methods and systems consistent with this invention generate a plurality of arbitrary phase modulation signals, and phase modulate each of the plurality of receive element signals with a different one of the phase modulation signals to form a plurality of phase modulated signals.

Abstract: An adaptive beamforming method for an antenna array is provided in which an array output is calculated based on a weight vector w, which is determined from an eigenvector corresponding to a maximum eigenvalue&lgr; of a generalized eigenvalue problem consisting of autocovariance matrixes Rxx and Ryy of received signal vectors y and x, respectively. The present invention dramatically decreases the total computation requirements by omitting complex matrix operations from the weight vector calculation, thereby making it possible to reduce the weight vector calculation time so as to form the beam pattern for the array antenna system in real time.

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: A system and method for forming a beam and creating nulls. The inventive method combines frequency domain suppression technology for narrow-band jammer rejection with orthogonal weighting using Eigen analysis for jammer nulling and signal beam-forming for an array antenna system. The inventive system is adapted for use with an adaptive array antenna having a plurality of radiating elements. The system includes a frequency domain suppressor connected to the array antenna and an orthogonal weighting subsystem connected to the frequency domain suppressor. In the illustrative implementation, signals received by each radiating elements are processed by an analog front-end and digitized. The frequency domain suppressor includes a Fast Fourier transformer (FFT) and a frequency domain suppressor for each element in the array. The frequency domain suppressor further includes a threshold evaluator which reads the signals output by the FFT's and provides threshold controls to the spectral suppressors.

Abstract: An adaptive beamforming method for an antenna array is provided in which an array output is calculated based on a weight vector w, which is determined from an eigenvector corresponding to a maximum eigenvalue&lgr; of a generalized eigenvalue problem consisting of autocovariance matrixes Rxx and Ryy of received signal vectors y and x, respectively. The present invention dramatically decreases the total computation requirements by omitting complex matrix operations from the weight vector calculation, thereby making it possible to reduce the weight vector calculation time so as to form the beam pattern for the array antenna system in real time.

Abstract: A signal detector is provided in which complex samples of a received signal are multiplied by data representative of a hypothesis, and the resulting product data is coherently integrated over a desired duration to provide correlation data representative of the level of correlation between the hypothesis and the signal. In one embodiment, the signal detector is part of a GPS receiver.

Abstract: A nulling direct radiating array (30) that includes a main phased array (32) and a plurality of auxiliary arrays (70, 72, 74) symmetrically disposed about the main array (32). The main array (32) includes a plurality of antenna elements (34) and a beam forming system (56) that generates one or more channels made up of several pixel beams. The pixel beams from the main array (32) are connected to a nulling processor (108) along with the combined signal from the antenna elements (80) of the auxiliary arrays (70, 72, 74). An adaptive weighting network (112) and an adaptive weight generator (114) within the nulling processor (108) determine whether a jamming signal exists in the channel beam, and weight the pixel beams from the main array (32) accordingly to block the jamming signal. The auxiliary arrays (70, 72, 74) provide a wider beam aperture that is able to more narrowly define the null in the radiation pattern of the main array (32).

Abstract: Signals in the form of wave elements of one or more subscriber signals are received at a receiving device assigned a number Ka of receiving sensors and the direction of the signals is estimated. Ka received signals are received via the receiving sensors and are composed of at least one subscriber signal which has a transmitter-specific fine structure impressed on it. A kth subscriber signal, with k=1 . . . K, is transmitted by means of Kd wave elements whose directions of arrival at the receiving location differ. Channel impulse responses assigned to the Ka receiving sensors are determined from the received signals, and the direction of arrival of at least one wave element is determined from the channel impulse responses. The direction estimation can advantageously be used in mobile radio, radar, sonar or seismic measurement systems.

Abstract: An array antenna is composed of an antenna section, adaptive transmission sections 3−1 to 3−M, and a transmission antenna weight-producing section 4. The antenna section has antenna elements 2−11 to 2−MN arranged linearly on each of sides or sectors of M in a polygon. The adaptive transmission sections form a directional pattern having a gain in the direction of a desired signal for each sector and send a desired signal. The transmission antenna weight-producing section produces transmission antenna weights of M for each sector. A directional pattern having a high transmission gain roughly proportional to the number of antenna elements near a direction vertical to a straight line can be formed.

Abstract: By estimating the movement direction of a communication partner, the radiation pattern is forcibly rotated to thereby form a correct radiation pattern. Specifically, an apparatus of the present invention includes reception radiation pattern control section for providing a reception signal from an antenna with a first reception radiation pattern by a first control signal, radiation pattern control section for providing the abovementioned reception signal with a second reception radiation pattern by a second control signal based on an output of movement direction estimating section for estimating a movement direction of a transmitting side, and a reception signal processing system having multiplication section for multiplying the abovementioned reception signal by the first control signal and the second control signal.

Abstract: The object of the invention is to suppress relative power of grating lobes in electronic scanning radar apparatus. This radar apparatus is a radar apparatus comprising a transmitting antenna and a receiving antenna, the receiving antenna being an array antenna having a plurality of antenna elements, the radar apparatus being adapted to effect electronic scanning of an antenna beam of the receiving antenna, wherein each of the plurality of antenna elements is comprised of a plurality of elemental antennas, so as to have a predetermined directional pattern, and wherein a synthetic pattern of the directional pattern of each antenna element and a directional pattern of the transmitting antenna has a depressed shape of relative power at an angle where a grating lobe of the receiving antenna appears.

Abstract: A method for positioning plural electromagnetic sensors in an array including the steps of: (1) designating one of the two sensors of the plural sensors that are a greatest distance apart as a point of origin of a reference system, (2) encoding in genotype form, the coordinates of the sensors relative to the reference system, and (3) applying a genetic algorithm to the encoded genotypes to obtain a given phenotype associated with a desired pattern. The method can be applied to the optimization of antenna arrays, especially planar or linear arrays.

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 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: An antenna system is made up by a main antenna and a sub antenna which is adjacent the main antenna in a direction not perpendicular to the direction of beam scan of the main antenna and which has a beam axis coincident with a beam axis of the main antenna. Antenna beams of the antenna system are scanned by a scan device. Received signals of both the antennas are subjected to a multiplication process under phase coherent condition in a phase-coherent multiplying device. A signal corresponding to a maximum frequency component in the output signal of the phase-coherent multiplying device is output by a frequency discriminating device and then subjected to a signal conversion process in a signal converting device. Information about a radio wave source only in the direction of the antenna beams is thus obtained.

Abstract: A desired signal is received at first and second antennas. Output signals of the first and second antennas are orthogonal-detected by first and second signal conversion circuits and thereby converted into first and second baseband signals. A complex conjugation circuit generates a complex conjugation signal by calculating a complex conjugation of the second baseband signal. The first baseband signal and the complex conjugation signal are multiplied by a multiplier. A direction estimation circuit estimates a direction of the desired signal by effecting an inverse tangent calculation and an inverse cosine calculation on an output signal of the multiplier.

Abstract: Hard-wired analog adaptive cancellation for microwave receivers to cancel the interference generated by co-located transmitter employs a circuit having two or more quadrature taps on a delay line. The least and greatest delays provided by the delay line taps are selected so that the copies of the transmitted signals provided by the respective taps bracket the timing of the portion of the transmitted signal that leaks into the collocated receiver's input. Samples of received signals corrupted by interference from the transmitter are mixed with delayed samples of a transmission reference signal to develop a cancellation signal.

Abstract: An antenna system comprising two similar antennas with a monopulse feed system is scanned while transmitting in-phase radio waves from the two antennas. Reflected radio waves are received by the two antennas and fed to a hybrid circuit which in turn produces a sum signal .SIGMA. and a difference signal .increment.. After detection is performed by a detector, a signal processing unit performs double differential processing on the sum signal .SIGMA. and the differential signal .increment.. In this processing step, the sum signal is output only if the double differential coefficient of said sum signal is equal to or less than a predefined positive real number value and if the double differential coefficient of said difference signal is equal to or greater than a predefined negative real number value, and a zero signal is output in any other cases. Thus, the beam width of an antenna pattern is compressed without missing a necessary output signal.

Abstract: A technique for improving sidelobe canceller performance by blocking the canceller output signal upon sensing reduced main channel interference accompanied by an increased sidelobe canceller output. Two signal processing networks form the difference between successive output signals from a radar antenna and sidelobe canceller respectively. The difference signals are multiplied together and the product used to control passage and preclude utilization of the canceller output signal when reduced jamming interference occurs.

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: An antenna system comprises a main antenna for use of transmission and reception and a dedicated sub-antenna for use of reception. The antenna beam of the antenna system is scanned in the direction of a beam width to be compressed. Both received signals of the main antenna and the sub-antenna are fed to a signal processing circuit and a multiplying circuit, and converted to power signals and then multiplied each other. In this processing, only if the cosine value corresponding to the phase difference between the received power signals of the main antenna and the sub-antenna is positive, the multiplication between the received power signals is carried out and the result is further multiplied by the cosine value, and then the obtained signal is output as a final output signal.

Abstract: A multifunction antenna system is provided which has adaptive beam forming capabilities for transmitting and receiving signals having various beam patterns over a hemispherical field of view. The antenna system includes a beamformer having an array of N spiral arm elements for transmitting and receiving a radiating beam. N analytic voltage signals are produced by the N cylindrically symmetric spiral arm elements in relation to the radiating beam. A beam processor is further provided for selecting the appropriate combination of vector weight coefficients in response to input data. The beam processor loads the selected N vector weights into a vector weighter. In the transmit mode, the vector weighter multiplies the selected vector weights by an input signal to produce the N analytic signals which are then applied to the multiple arm spiral antenna and transmitted therefrom.

Abstract: A beam of a main antenna is scanned at a constant speed in the direction of compression of the beam width over the range of from (c-a) degree to (c+a) degree with an arbitrary angle c set as a reference angle, and a beam of a sub antenna is scanned by using a phase shifter at a constant speed in the direction of compression of the beam width over the range of from (c-b) degree to (c+b) degree where b represents an angle corresponding to the first zero point of a pattern of the sub antenna and larger than the 1/2 scan angle a of the main antenna. Received signals of both the antennas obtained by the beam scans are subjected to an in-phase multiplication process in a multiplying circuit for beam compression of the received pattern of the main antenna.

Abstract: An antenna system including a sub antenna adjacent a main antenna in the direction where a beam width of the main antenna is to be compressed and a beam axis of the sub antenna is coincident with a beam axis of the main antenna. Antenna beams of the antenna system are scanned in the direction of compression of the beam width. Received signals of the main antenna and the sub antenna are subjected to a step of signal processing and multiplication process in a signal processing and multiplying circuit. In that step, only when the received pattern waveform of the main antenna and the received pattern waveform of the sub antenna are both at local maximum levels, the received signal of the sub antenna is output and subjected to the multiplication process for preventing the occurrence of distortion in the received pattern.

Abstract: A method for reducing side lobes wherein an antenna system comprises a main antenna and a sub antenna which does not have an isotropic antenna pattern in a direction (X direction) of an orientation of a side lobe of the main antenna to be reduced which is arranged in such a way that the sub antenna adjoins the main antenna in the direction (Y direction) perpendicular to the X direction and the beam axis of the sub antenna coincides with the beam axis of the main antenna; wherein an antenna beam of the antenna system is scanned in the X direction and a signal received with the main antenna is multiplied by a signal received with the sub antenna on the condition that phases of both signals coincide with each other.

Abstract: An antenna system comprises: a main antenna; a first sub antenna arranged in such a way that the first sub antenna adjoins the main antenna in the X direction which is the orientation of a beam width of the main antenna to be reduced and the beam axis of the first sub antenna coincides with the beam axis of the main antenna; and a second sub antenna arranged in such a way that the second sub antenna adjoins the main antenna in the Y direction perpendicular to the X direction and the beam axis of the second sub antenna coincides with the beam axis of the main antenna; wherein an antenna beam of the antenna system is scanned in a direction other than the X and Y direction and multiplication is carried out between a signal received with the main antenna and each signal received with each sub antenna on the condition that phases of these signals coincide with each other so that a two-dimensional reduction in a beam width is achieved.

Abstract: A spread-spectrum communication system uses a PN code which ensures that the side lobe of a self-correlation function represents zero on both parts of a sender and a receiver.

Abstract: To eliminate the complexity and the weight involved in the use of a Butler matrix, the present invention matrix antenna array uses a combination of processors and analog multipliers for weighting the signals, either to be transmitted or received, from the corresponding antenna element of the array. Since the analog multipliers are adaptable to operate in the microwave frequency, the control signals can be multiplied with the radar signal directly so that complexity of construction, bulkiness and heavy weight are eliminated from the matrix antenna array of the present invention.

Abstract: A communications satellite has several radiating elements connected respectively to the output ports of a hybrid matrix power amplifier the input ports of which are connected to respective output ports of a low level beam forming network. The low level beam forming network has input ports to which are applied individual beam signals and these are combined within the network to provide at the network output ports different component sums of the input signals. By selecting appropriate connections between the beam forming network and the hybrid matrix power amplifier on the one hand and between the hybrid matrix power amplifier and the radiating elements on the other hand, desired beam overlap and equal power amplifier loading can be achieved.

Abstract: A direction finding method and apparatus for a radio signal source, modulated by a digital information signal and existing in a heavy interference environment, is based on cyclic crosscorrelation. The direction finding technique exploits the second order periodicity of a transmitted signal having digital modulation, whereby the technique is immune to narrow-band interference. Radio frequency signals are received by two spaced antennas, and the signal of interest can be considered as a cyclostationary process. The signal time of arrival difference between the two antennas is determined using a cyclic crosscorrelation method. This is implemented by sending the electrical signals, developed by the antennas, through a variable delay device, then to a balanced mixer. The composite signal from the mixer is sent to a band-pass filter whose center frequency is equal to the baud rate of the signal of interest.

Abstract: A null processing receiver apparatus that receives and combines together a number of modulated information signals in such a fashion that an interference or jamming signal superimposed on each received signal is substantially eliminated from the combined signal. The apparatus first demodulates each received signal to baseband, to produce a primary demodulated signal and one or more auxiliary demodulated signals. The apparatus then appropriately weights the one or more auxiliary signals and sums together the weighted signals with the primary signal to produce a sum signal in which the interference is substantially nulled out. The weighting is based on a cross-correlation of the sum signal with the baseband signals themselves.