Abstract: 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 ½ 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.

Abstract: 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 ½ 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Methods (200, 300) for determining a reference signal (Vref). The methods involve (202, 204, 302, 304) sensing at a first location along the transmission media (108, 502) a first signal (Vf) propagated thereover in a forward direction and a second signal (Vr) 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 (206, 306) by adding the first and second signals together. A difference signal (D) is determined (208, 308) by subtracting the second signal from the first signal. Thereafter, a first exponentiation signal (ES) is determined (210, 310) using S. A second exponentiation signal (ED) is determined (212, 312) using D. The first exponentiation signal is subtracted (214, 314) from the second exponentiation signal to obtain a reference signal (Vref). Vref can be determined at any location along the transmission media.

Abstract: Systems (100) and methods (500) for method for providing a redundant or distinct transmission feature to a communication system (100). The methods involve (508) detecting if there is a communication system fault. If a communication system fault is detected (508:YES), then (512) a plurality of modified transmit signals are generated by combining a transmit signal with a plurality of complex weights (W1, W2, W3). The modified transmit signals are then (514) transmitted from a plurality of antenna elements (106a, 106b, 106c) of the communication system to an object of interest (108). If a communication systems fault is detected (508:NO), then (526) 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 (528) synchronously transmitted from the antenna elements.

Abstract: Predistorting an input signal prior to amplification in an RF power amplifier (206) 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 (224). After modification, each of the sub-bands are summed together to obtain a predistorted input signal for an RF power amplifier (206).

Abstract: 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.

Abstract: 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 (ftrue) 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 ftrue.

Abstract: 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.

Abstract: Methods for compensating for phase shifts of a communication signal. The methods involve determining a first reference signal (Vref-1) at a first location along a transmission path and a second reference signal (Vref-2) at a second location along the transmission path. Vref-2 is the same as Vref-1. At the first location, a first phase offset is determined using Vref-1 and a first communication signal. At the second location, a second phase offset is determined using Vref-2 and a second communication signal. A phase of a third communication signal is adjusted at the second location using the first and second phase offsets to obtain a modified communication signal. The first, second, and third communication signals are the same communication signal obtained at different locations along the transmission path.

Abstract: Systems comprising sensing devices (SD), a signal combiner (SC), signal subtractors (SS), and signal multipliers (SM). SD (116, 402, 504, 604, 620, 708a, 708b, 708c) senses at a first location along a transmission media (TM) a first signal (Vf) propagated over TM (100, 502, 602, 702, 1025) in a forward direction and a second signal (Vr) propagated over TM in a reverse direction opposed from the forward direction. SC (406, 508, 606, 806) computes a Sum signal (S) by adding Vf and Vr together. A first SS (408, 508, 606, 806) computes a Difference signal (D) by subtracting Vr from Vf. A first SM (410, 510, 608a, 808a) computes a first Exponentiation signal (ES) using S. A second SM (412, 512, 608b, 808b) computes a second Exponentiation signal (ED) using D. A second SS (414, 514, 614, 816) subtracts ES from ED to obtain a reference signal (Vref).

Abstract: 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.

Abstract: 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).

Abstract: 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.

Abstract: A system and method for model-based control of a the physical system, based on a computer simulation model approximating operating characteristics of at least a portion of the plurality of components and having one or more model parameters for adjusting a modeled operating characteristic of at least one of the plurality of components is provided. In the system and method at least one active input parameter for the physical system is generated based on current values for the model parameters and the computer simulation model and at least one measured system parameter value and at least one modeled system parameter value are obtained for measuring the performance of physical system responding to the active input parameter. The system and method also evaluate a difference between the measured system parameter value and the modeled system parameter value and update the current values for the model parameters to minimize the difference.

Abstract: Systems (100) and methods (500) for method for providing a redundant or distinct transmission feature to a communication system (100). The methods involve (508) detecting if there is a communication system fault. If a communication system fault is detected (508:YES), then (512) a plurality of modified transmit signals are generated by combining a transmit signal with a plurality of complex weights (W1, W2, W3). The modified transmit signals are then (514) transmitted from a plurality of antenna elements (106a, 106b, 106c) of the communication system to an object of interest (108). If a communication systems fault is detected (508:NO), then (526) 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 (528) synchronously transmitted from the antenna elements.

Abstract: Methods (200, 300) for determining a reference signal (Vref). The methods involve (202, 204, 302, 304) sensing at a first location along the transmission media (108, 502) a first signal (Vf) propagated thereover in a forward direction and a second signal (Vr) 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 (206, 306) by adding the first and second signals together. A difference signal (D) is determined (208, 308) by subtracting the second signal from the first signal. Thereafter, a first exponentiation signal (ES) is determined (210, 310) using S. A second exponentiation signal (ED) is determined (212, 312) using D. The first exponentiation signal is subtracted (214, 314) from the second exponentiation signal to obtain a reference signal (Vref). Vref can be determined at any location along the transmission media.