Harris Corporation

Specialized Arrays, Inc.

G Patrick Martin

Kathleen Marie Minear

Christopher Douglas Moffatt

James G Tonti

William C Adams, Jr

Edward Ray Beadle

John Fitzgerald Dishman

Mark Larry Goldstein

Richard John Nink

John Roach

H Richard Phelan

Allan V Dianic

Lynda Margaret Ralston

James Tonti

The present technology describes a widely-spaced antenna radar array for Space Domain Awareness capable of object detection, characterization, imaging and, if unfriendly, threat mitigation. It features (1) very high angular resolution due to the very wide spacing of the sensors, enabling the detection of baseball size objects in GSO, (2) operation at high frequencies enabling characterization of smaller objects because of the ability to mitigate tropospheric effects, (3) operation at varied frequencies enabling threat mitigation and imaging, (4) immediate orbit determination in a single pass without the need for long-arc tracking due to the wide spacing and high precision angle of arrival (AOA) and (5) mitigation of grating lobes caused by the sparse antenna configuration, enabling the sensors to be placed at great distances.

System and method for space domain awareness using a sparse widely-spaced radar aperture

The trirectangular tetrahedron array provides nearly constant gain over a hemisphere, by adaptively combining signals from elements, having substantially cosine-squared power patterns, on orthogonal faces. By using a deterministic aperiodic lattice, the array can use higher gain elements rather than lower gain elements for traditional wide-scan phased arrays. Thus, the number of elements needed can be reduced by more than a factor of two. Importantly, element spacing is increased with this design, thus lowering mutual coupling and the associated potential for scan blindness. Higher gain elements require spacing exceeding &#xbd; wavelength can have grating lobes. This is addressed with an aperiodic lattice designed to ensure that no grating lobe can form. By connecting two trirectangular tetrahedrons by their bases and mounting on an air/space-based platform, nearly spherical coverage with constant gain results.

Tetrahedral array for constant gain hemispherical coverage

A system and method for operating a communications or radar system wherein the system is a closed-loop coherent transmit array consisting of a plurality of antenna elements that may be widely-spaced, many wavelengths apart, an array control system, and a remote receiver that can feedback a measure of the transmit performance, and is a cooperative receiver, a bent-pipe, or a reflector. The method involves generation of weights which are applied to the array transmit signals based on feed-back data from a remote receiver compensating for at least one: circuit, propagation, and polarization phase errors. The method correlates feedback performance changes with transmit weight perturbations, enabling maximization of transmitted power delivered to the remote receiver. The method further involves an optimization control process that can be coordinated, with systematic weight perturbations and adjustment, or which can be operated asynchronously and autonomously, nevertheless achieving maximization of the received signal power.

System and method for widely-spaced coherent transmit arraying using a remote receiver

A system for detection and orbit determination of Earth orbiting objects includes a first plurality of sensors including at least one first antenna. The at least one first antenna is configured to point in a stare mode to broadcast a first detection signal at an angular region centered on an equatorial plane to maximize detection of orbiting objects regardless of altitude, grade, or inclination. The first antenna may be configured to stare at a low inclination angle, and may be configured to stare at one of due east and due west along the equator.

System and method for detection and orbit determination of earth orbiting objects

Systems () and methods () for method for providing a redundant or distinct transmission feature to a communication system (). The methods involve () detecting if there is a communication system fault. If a communication system fault is detected (:YES), then () a plurality of modified transmit signals are generated by combining a transmit signal with a plurality of complex weights (W, W, W). The modified transmit signals are then () transmitted from a plurality of antenna elements () of the communication system to an object of interest (). If a communication systems fault is detected (:NO), then () a plurality of redundant or distinct transmit signals are generated by combining the transmit signal with a plurality of first orthogonal or approximately orthogonal numerical sequences. The redundant or distinct transmit signals can then be () synchronously transmitted from the antenna elements.

Code division multiple access based contingency transmission

Methods () for determining a reference signal (V). The methods involve () sensing at a first location along the transmission media () a first signal (V) propagated thereover in a forward direction and a second signal (V) propagated thereover in a reverse direction opposed from the forward direction. The second signal being a reflected version of the first signal. A sum signal (S) is determined () by adding the first and second signals together. A difference signal (D) is determined () by subtracting the second signal from the first signal. Thereafter, a first exponentiation signal (E) is determined () using S. A second exponentiation signal (E) is determined () using D. The first exponentiation signal is subtracted () from the second exponentiation signal to obtain a reference signal (V). Vcan be determined at any location along the transmission media. Vcan be used to control the phases and/or amplitudes of communication signals.

Methods for determining a reference signal at any location along a transmission media

Predistorting an input signal prior to amplification in an RF power amplifier () includes isolating a plurality sub-band signals, each representing a portion of the input signal s(t). The method includes independently modifying an amplitude and a phase of each of the plurality of sub-band signals. The modification of the amplitude and/or phase is performed using a set of signal weighting parameters (weights) w and W, controlling linear and nonlinear modifications respectively, which are determined in an adaptive process by an adaptive controller (). After modification, each of the sub-bands are summed together to obtain a predistorted input signal for an RF power amplifier ().

Linearization of RF power amplifiers using an adaptive subband predistorter

Systems and methods for operating a communications system. The methods involve computing one or more complex weights to be applied to transmit signals and receive signals by beamformers. The complex weights are based at least on configuration data for the communications system. The methods also involve applying a first plurality of weight corrections to the complex weights based on phasing errors occurring in a communication path inclusive of a control system and antenna elements. The methods further involve applying a second plurality of weight corrections to the complex weights based on phase differences at the antenna elements relative to a reference location for the receive signals.

Compensation of beamforming errors in a communications system having widely spaced antenna elements

A method for correcting transmission phasing errors in an plurality of antenna elements is provided. The method includes receiving at least a first signal having a first frequency at the plurality of antenna elements at an angle of arrival (AOA). The method also includes identifying an actual fractional wavelength value (f) for the first signal received with respect to a reference location for at least one of the plurality of antenna elements, obtaining a estimated phase propagation of the first signal at the one of the plurality of antenna elements relative to the reference location based at least on configuration data for plurality of antenna elements, and updating the configuration data associated with the AOA for the one of the plurality of antenna elements based on the estimated phase propagation and f.

Systems and methods for compensating for transmission phasing errors in a communications system using a receive signal

A method for operating a communications system is provided. The method includes receiving a plurality of signals at a plurality of antenna elements, the plurality of signals arriving at the array of antenna elements at a plurality of angles of arrival (AOAs) with respect to a reference location. The method also includes calculating a plurality of differential distance vectors between the plurality of antenna elements and the reference location, each of the plurality of differential distance vectors associated with one of the plurality of AOAs and at least one of the pluralities of signals. The method further includes obtaining a plurality of actual phase center locations for the plurality of antenna elements based on the plurality of differential distance vectors and the plurality of AOAs and providing a correction to configuration data for the array of antenna elements based at least on the plurality of actual phase center locations.

Systems and methods for determining element phase center locations for an array of antenna elements

RF amplifier system () incorporating feedforward linearization. The system includes a digital waveform source () generating digital data s(t) representative of at least one analog signal. The system also includes a feedforward linearization circuit for reducing a distortion of an RF power amplifier (). The feedforward linearization circuit includes a differential amplifier () arranged for generating an error signal. The error signal is determined based on a difference between the distorted RF output signal and an analog RF reference signal () generated from the digital data.

Feedforward linearization of RF power amplifiers

Method for accurately measuring hearing loss includes the steps of selecting a series of audio tones within the normal range of hearing () and then measuring a relative sensitivity of a test subject with respect to the ability to hear each of the audio tones, exclusive of the effects of tinnitus. () The relative sensitivity of the test subject to hear the tones can be measured by determining () for each tone an intensity necessary for the test subject to hear the tones at a subjectively equal loudness level which is selected to exceed a perceived level of noise attributable to tinnitus for the test subject.

High fidelity hearing restoration

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

All digital phased array using space/time cascaded processing

Blind source separation (BSS) of statistically independent signals with low signal-to-noise plus interference ratios under a narrowband assumption utilizes cumulants in conjunction with spectral estimation of the signal subspace to perform the blind separation. The BSS technique utilizes a higher-order statistical method, specifically fourth-order cumulants, with the generalized eigen analysis of a matrix-pencil to blindly separate a linear mixture of unknown, statistically independent, stationary narrowband signals at a low signal-to-noise plus interference ratio having the capability to separate signals in spatially and/or temporally correlated Gaussian noise. This BSS provides the ability to blindly separate signals in situations where no second-order technique has been found to perform the blind separation satisfactorily, for example, at a low signal-to-noise ratio when the number of sources equals the number of sensors or when the noise is spatially and temporally colored.

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Merritt Island, FL, United States of America

G Patrick Martin