Abstract: A monopulse tracker includes multiple dual-axis monopulse antenna systems that are angled with respect to one another. The orientations of the monopulse antenna systems create a much larger field of view for the monopulse tracker to eliminate the need to steer the monopulse tracker. The monopulse tracker can be configured to estimate a position of an object based on tracking information received from more than one monopulse antenna system therefore increasing the accuracy of the estimated position. The multiple monopulse antenna systems can be arranged in a low-profile housing to facilitate use of the monopulse tracker on aircraft.

Abstract: The present disclosure relates to a radio altimeter including a path extending unit positioned in a signal transmission path or a signal reception path of the radio altimeter, wherein the path extending unit delays a signal received from the outside to reduce a dynamic range of the radio altimeter.

Abstract: The present invention regards a method of operation of a real aperture radar system for surveillance of the Earth's surface, said real aperture radar system being installed on a space vehicle/platform that moves in a direction of flight and comprising a transceiving antenna, or a transmitting antenna and a receiving antenna, which is/are electronically steerable. All the radar pulses are transmitted: with a predefined pulse repetition frequency and a predefined timing of the scanning cycle such that to guarantee a complete coverage of each of the N swaths parallelly to the direction of flight; and by using a frequency agility technique.

Abstract: A method for performing uplink transmission in a time domain transmission unit includes receiving, from a base station, hopping-mode information indicating whether a frequency hopping is an inter-slot hopping or an inter-subframe hopping and performing the uplink transmission using a resource block in the time domain transmission unit.

Abstract: An improved approach to direction finding using a super delta monopulse beamformer is disclosed. A super delta channel signal that includes direction finding information from two circular delta channels is formed and output by the super delta monopulse beamformer. This super delta channel signal uses only two channels, but is able to realize the accuracy of conventional three channel systems.

Abstract: An apparatus comprises a plurality of antenna elements, a plurality of digital signal processing devices for supplying phase-and-amplitude-weighted digital baseband signals, a beamforming processor for processing the weighted digital baseband signals to adaptively form a plurality of beam patterns for the antenna elements, a plurality of digital modulators for converting the digital baseband signals into intermediate frequency digital signals, and a modulator for modulating in-phase and quadrature components of the intermediate frequency digital signals to produce composite radio frequency output signals for the antenna elements. Receiving apparatus, and methods of transmitting and receiving a plurality of signals on a plurality of antenna elements are also provided.

Abstract: A proposed spread spectrum signal receiver includes a radio front-end unit and a processing unit. The radio front-end unit, in turn, has an antenna, a digitizing circuit and a primary buffer unit. The antenna is adapted to receive radio signals (SHF) from a plurality of signal sources, and the digitizing circuit is adapted to downconvert and filter the received signals (SHF), and generate sample values (SBP-D) thereof. The primary buffer unit is adapted to temporarily store the sample values (SBP-D) from the digitizing circuit and allow the processing unit to read out a first set of stored sample values (SBP-D) contemporaneously with the storing of a second set of sample values (SBP-D) in the primary buffer unit. The processing unit is adapted to receive the sample values (SBP-D) from the primary buffer unit, and based thereon, produce position/time related data (DPT).

Abstract: A surface acoustic wave (SAW) expander based transmitter and correlator based receiver comprises SAW devices that perform expander or correlator functions based on the types of signals inputted to the SAW devices. The SAW devices incorporate chirp with adaptive interference and programmable coding capabilities. The SAW devices and method of operating the devices allow the implementation of very low power radios that overcome problems with temperature drift, lithography constraints and interference and jamming suffered by prior art implementations.

Abstract: Disclosed is a spread spectrum clock generator which includes: a first delay control type oscillator that variably controls an oscillation period at a control period interval according to a control signal; a control circuit; a maximum modulation value determination circuit that determines a maximum modulation value from a predetermined value, a frequency control signal, and a given modulation degree setting signal; a modulation signal generation circuit that receives the maximum modulation value from the maximum modulation value determination circuit and generates a modulation control signal within the maximum modulation value; and a second delay control type oscillator that receives a value obtained by adding the modulation control signal from the modulation signal generation circuit to the frequency control signal as a control signal and variably controls the oscillation period of an output clock signal at the control period interval according to the control signal.

Abstract: Channel quality can be detected accurately in a wireless transmission system such as an HSDPA method. In the case of estimating a channel quality of a signal transmitted by a Code Division Multiple Access method and of estimating the channel quality in a system having a synchronization channel not orthogonal to a channel receiving data, a noise component of a desired channel is estimated; degree of a noise component caused by the synchronization channel is estimated with respect to the estimated noise; and a channel quality of a receiving channel is detected based on the estimated degree of the noise component.

Abstract: A frequency hopping communications system is disclosed. A server is adapted to have one or more radio head interface modules and a call processing software module. The call processing software module performs modulation and demodulation of voice and data streams using one or more air interface standards. A radio head unit is coupled to the radio head interface module over one or more transport mediums and communicates with one or more subscriber units using the one or more air interface standards. The one or more radio head interface modules, are adapted to receive frequency channel hopping information, including a channel and a time to hop trigger, from the call processing software module for one or more of a plurality of communication channels.

Abstract: An apparatus and method for channel estimation and CP reconstruction in an OFDM-STBC mobile communication system are provided. An ISI canceller cancels ISI signal components from first and second received symbol sequences. A cyclicity restorer cancels ICI signal components from the ISI-cancelled first received symbol sequence and the ISI-cancelled second received symbol sequence. A recoverer acquires the recovered sequence estimates of the ICI-cancelled first received symbol sequence and the ICI-cancelled second received symbol sequence by decoding. The ICI cancellation of the ISI-cancelled first and second received symbol sequences and the ISI cancellation of the second received symbol sequence are iterated a predetermined number of times.

Abstract: A code division multiple access (CDMA) communication system using spread spectrum signaling over a communication bandwidth uses two different signal spectra generated using two different respective spreading code formats, such as NRZ code formatting and staggered Manchester code formatting, for respectively providing nonsplit spectra having a center peak and split spectra having a center null. The spectra are combined during transmission as a CDMA communication signal having a composite spectrum. The use of different code formats produces the composite spectrum of respective center peak and center null spectra that enables increased channel capacity.

Abstract: The invention provides an adaptive frequency hopping spread-spectrum (FHSS) transmission system and method, which efficiently utilizes available transmission bandwidth, whilst providing robustness to jamming techniques in wireless communication systems. The proposed technique operates by transmitting a wide-band signal over multiple, single-carrier, parallel transmission subbands, which may occupy non-contiguous frequency regions. The proposed scheme exhibits significant gain in error rate performance, as compared to a data rate equivalent single-subband system in the presence of signal jamming and/or interference without a reduction in the transmission data rate nor an increase in transmitter power. In addition, the proposed system and method are adaptive and enable more efficient use of the available bandwidth for communicating, thus increasing the overall bandwidth utilization of the system.

Abstract: A method and a standard radio wave receiver for receiving a plurality of standard radio waves respectively having signal configurations in accordance with respective specifications which define carrier channels and formats and for decoding time code signals carried by the standard radio waves. The method extracts at least part of a bit waveform common to the specifications as a extracted signal from a waveform of each of the time code signals given by each of the carrier channels, synchronizes bits to each of the time code signals in accordance with the extracted signal, determines an evaluation index indicating good or bad of a reception condition for each of the carrier channels from the bit waveform, and selects a single channel from the carrier channels in accordance with the evaluation index.

Abstract: An ultra wideband (UWB) receiver system operable to process a high order Gaussian pulse includes an integrator group, a correlator circuit and a comparator circuit. The integrator group includes an input coupled to receive the high order Gaussian pulse and an output coupled to the correlator circuit, the integrator group having two or more successively coupled integration stages, each integration stage operable to integrate, over a predefined time period, the signal received thereby, the integrator group operable to output, in response, a lower order Gaussian pulse. The correlator circuit is coupled to receive the lower order Gaussian pulse, and is operable to output a correlated output signal corresponding to the correlation between the lower order Gaussian pulse and a predefined reference signal.

Abstract: A method is presented for packet detection and symbol boundary location using a two-step sign correlation procedure. When the correlation crosses a threshold, a packet detection signal is generated to initiate processing of downstream blocks, and a symbol boundary location signal is generated for use in aligning data during processing.

Abstract: The invention relates to a spread-signal multiplexing circuit for frequency-multiplexing a plurality of spread signals that were generated in parallel according to the SSMA scheme. An object of the invention is to adapt to various degrees of multiplicity and to keep the SN ratio and the power efficiency high. To this end, a spread-signal multiplexing circuit of the invention comprises an amplitude monitoring part for multiplexing a plurality of spread signals and determining amplitude of a resulting signal in time-series order; a delaying part for delaying the spread signals in parallel by a time that is equal to a propagation delay time of the amplitude monitoring part; and a multiplexing part for generating a multiplexed signal by multiplexing the delayed spread signals while weighting the delayed spread signals in parallel using weights that are smaller as an average value of the determined amplitude is larger.

Abstract: In the method of processing signals, multi-path signals are received, channel estimates for the received multi-path signals are determined, and a combining operation is applied to the multi-path signals, the combining operation being a function of a correlation matrix of the received multi-path signals, a correlation matrix of estimates for channels of the received multi-path signals, a cross-correlation matrix of the channels and channel estimates for the received multi-path signals, and the channel estimates.

Abstract: A method of generating a composite signal includes the steps of: (a) generating a plurality of sub-carriers, each sub-carrier having a different frequency position in a frequency spectrum; (b) generating a plurality of codes; and (c) forming a plurality of code combinations from the plurality of codes generated in step (b). The method also includes the steps of (d) first modulating each sub-carrier using a respective one of the code combinations formed in step (c) to form a plurality of modulated sub-carriers; and (e) second modulating in-phase and quadrature components of a base carrier using the plurality of modulated sub-carriers to form the composite signal having multiple carriers. The composite signal is a constant envelope signal, and a single sideband signal.

Abstract: A method estimates a time of arrival of a signal received in a wireless communication system. An energy in a frame of a received signal is measured to determine a block in the frame, the block representing a coarse time of arrival of the received signal. Multiple time-delayed versions of a template signal are combined with the block of the received signal to select a particular template signal. The particular template signal identifies a particular chip representing a fine time of arrival of the received signal.

Abstract: The number of times for averaging operation for averaging a correlation value of a received signal and a reference signal is properly controlled. When the correlation value is not averaged, since a lower limit value TH_A of a correlation level of a distribution of timings of which a path exists is larger than an upper limit value TH_B of a correlation level of a distribution of timings of which a path does not exist, the correlation value of a path is hidden by noise. Since the averaging operation is repeated until the relation of TH_A>TH_B is satisfied, the averaging operation is stopped when the relation is satisfied. The TH_A and TH_B are decided in accordance with RSCP and ISCP of a pilot channel and RSSI of a received base band signal.

Abstract: A method of Partial Parallel Interference Cancellation (PPIC) is provided for recursively eliminating the Multiple Access Interference from a received signal. Such method is to use a recursion way to eliminate all the Multiple Access Interference (MAI) one by one from the received signal. Moreover, the present invention is to take the output of the pre-stage as the input of the present stage with the recursion method so that we can use only one operating circuit to obtain the function the MAI eliminating.

Abstract: In a method for tracking a radar target the imaginary part of the complex elevation error signal is utilized and the value of the complex elevation error signal is calculated for a plurality of frequencies in a repeated sequence. The value change between the different frequencies is used for determining the position within an unambiguous interval and the values calculated at the zero crossing are utilized as measure of the inclination which in turn is compared with inclinations calculated for zero crossings in a general case, whereby a single-valued (unambiguous) interval and position can be determined and thereby the associated elevation angle or target height can be calculated. The method is specifically useful for tracking at low height where multi-path propagation poses a problem in tracking according to known methods.

Abstract: This radar receiver, in particular for a radar having an antenna with beam forming through computation, comprises essentially means for matched filtering having a bandwidth B, means for amplitude and phase detection, and means for analog-to-digital conversion, and is such that said means for analog-to-digital conversion work on the intermediate-frequency signals, at a frequency much higher than said intermediate frequency. The receiver can be fully constructed in gallium arsenide technology.

Abstract: The radar system includes a sum and difference network coupled to a conventional monopulse type antenna. The difference signals or error signals are applied into a modulator in space quadrature with electrical vectors in a direction transverse to the direction of propagation polarized at right angles to each other. A rotating magnetic field in the modulator causes any energy that is in line with this field to be continually rotated and applied to a coupler that is sensitive. During search the shutter is closed so that only unmodulated sum energy is passed through the circulator to the receiving unit. For tracking the shutter is opened and the reflecting post is positioned to reflect a selected portion of the error signal energy and pass a selected portion of the sum signal energy, both of which are absorbed in the isolator. The system provides a simplified selection of the lobing frequency by controlling the velocity of the rotating magnetic field at the modulator.

Abstract: A monopulse receiver includes a monopulse antenna and arithmetic unit for providing a monopulse sum signal, S, an azimuth difference signal, y, and an elevation difference signal, p, an imbalance correction circuit to provide a first composite signal defined as (y+jp) and a second composite signal defined as (y-jp), wherein j is an indicator of being in quadrature with the monopulse sum signal, and for interleaving the first and the second composite signal for providing a composite difference signal, D, and a combiner for providing a third composite signal defined as [S+D] and a fourth composite signal defined as [S-D].

Abstract: A method and a device which make it possible, simultaneously and in a perfectly identical manner, to process n analog signals (E.sub.1, E.sub.2 . . . ) of short duration. The device comprises n processing channels (V.sub.1, V.sub.2, . . . ) each receiving an analog signal and each possessing in series, a processing circuit (11, 12; 21, 22; . . . ) for frequency transfer (F.sub.1, F.sub.2, . . . ), and a delay circuit .tau..sub.1, .tau..sub.2, . . . (13, 23, . . . ) respectively. A set of switches (C.sub.1, C.sub.2, . . . , C'.sub.1, C'.sub.2, . . . ) interconnect the inputs and outputs of the various elementary processing channels (V.sub.1, V.sub.2, . . . ) in order to pass each signal through all the n elementary channels (V.sub.1, V.sub.2, . . . ) successively and sequentially, for a processing cycle. This permits the fine analysis of the echo signals received from a target consisting of several bright points, by a pulse compression radar.

Abstract: The isolation of mainbeam and sidelobe jamming signals from the desired signal being relayed by microwave communication links is accomplished by an antijamming antenna comprising a flat radome, a curved reflector and a transmit dipole. Positioned adjacent the dipole is a monopulse feed and comparator for main-beam jammers (dual-plane monopulse, multi-mode multilayer feed). Also forming part of the integrated antenna are auxiliary units for near-sidelobe and far-sidelobe jammers. An alternative embodiment includes a Cassegrain grating sub-reflector. Since the direction of the desired incoming signal in microwave communication links is precisely known, the antijamming antenna uses azimuth and elevation monopulse to make a spatial distinction between the desired incoming signal and the jamming signals.

Abstract: A monopulse receiver, wherein a desired wide dynamic range is achieved for range gated monopulse sum and difference signals, is shown to incorporate: (a) a multiplexer for time-multiplexing such signals; (b) a first and a second receiver channel responsive to the time-multiplexed signals, each such channel having a dynamic range less than the desired wide dynamic range and greater than one-half the desired wide dynamic range, the gains in such channels being offset so that together such channels have the desired dynamic range; (c) a first and a second sampler and analog-to-digital converter, respectively, responsive to the signals out of the first and the second receiver channel, for producing digital words indicative of the amplitude of each component signal in the time-multiplexed signals; and (d) logic and control means for forming bytes from predetermined portions of each one of the digital words and for selecting the byte indicative of the amplitude of each component signal.