Abstract: The integrity of operation of a GPS precision aircraft approach and landing system may be compromised by error producing effects of reflected multipath signals. An integrity monitor antenna system as disclosed may utilize both attenuation and shadowing of reflected multipath GPS signals to achieve extreme multipath mitigation of the order of 50 dB suppression. An antenna with a right-hand circular polarization pattern having a sharp cut off at the horizon may provide 30 dB suppression of reflected multipath signals. A signal absorbent ground plane bed of defined dimensions may provide 20 dB attenuation of incident multipath signals. A signal/processor may be employed to derive position error data for integrity monitoring, based upon differentials between a known fixed location and a current GPS-indicated location. Communication of identification of a subset of particular GPS satellites for common usage may also reduce potential error levels.

Abstract: Accuracy of derivation of local corrections to GPS signals for use for aircraft landing guidance is subject to effects of reflected multipath signals. Antennas with a near-spherical antenna pattern of right-hand circular polarization, except within a downward cone, provide suppression of reflected multipath GPS signals incident from all azimuth angles and all relevant elevation angles. For such an antenna a cylindrical top assembly may include spaced conductive disks with intermediate exciter members excited at increments of 90 degree phase and surrounded by a dielectric ring. A cylindrical base assembly may include signal absorbent top and side wall portions and a bottom conductive disk and may alternatively include a signal absorbent inner wall portion.

Abstract: In the absence of centrifugal force produced during rotation of helicopter blades, damage may result if a blade is rotated upward by wind or other forces. Lock units removably appended between the rotor assembly and each blade pitch housing attached to a helicopter blade are usable to restrict upward rotation. A base portion of a lock unit may be configured to be held in position by a removable pin device. An extendible device extending from the base portion to a surface of a blade pitch housing can be adjusted to press the base portion back against a surface of the rotor assembly. The lock unit thereby restricts these surfaces of the blade pitch housing and rotor assembly from moving closer to each other and thereby restricts upward rotation of the blade pitch housing and its attached helicopter blade. The lock units are readily removable in preparation for returning a helicopter to active use.

Abstract: Vertical array antenna systems can provide broadband data link operation with reduction of susceptibility to low angle multipath effects, for communication during carrier landings by aircraft and other applications. In a relatively small package, an antenna system may include a stack of sub-arrays, each including four dipoles provided as configurations of downward and upward extending dipole arm members which are vertically separated by an annular slot excited by vertical probes. Excitation of the dipoles may be provided via excitation of the annular slot by the probes. Intercoupling-reduction disk units may be positioned between vertically adjacent sub-arrays. Pattern cutoff characteristics suitable for aircraft carrier landing operations (e.g., for reliable DGPS communications) at or near the horizon may be provided by excitation of individual sub-arrays at predetermined relative levels and with pattern phase reversal between lower and upper sub-arrays.

Abstract: An instrument landing system (ILS) provides signals in space receivable by an aircraft in flight to identify, for example, a point in space at which to start an approach along a glide slope path to a touchdown point on a runway. Atmospheric, ground and other conditions may cause transmission anomalies, so that the ILS signals identify a point in space displaced from its intended position. Systems and methods employed in flight use GPS or other positional data to determine the current displacement of such point, as identified by received ILS signals, from its intended position consistent with ILS specifications. In addition to reception and use of ILS and GPS signals, data on geographic runway location and correct ILS signal in space parameters is used for reference purposes in determining signal in space position discrepancies, glide slope path angular discrepancies, or both.

Abstract: An adaptive antenna system may be used with a GPS system to improve operation in the presence of interference signals. A resulting adapted antenna pattern will cause array pattern distortions affecting GPS satellite signals received at some signal arrival angles. By determining values of array factor distortions applicable to a GPS satellite signal received at a specific arrival angle via a specific adapted array pattern, a correction signal may be developed for use to mitigate the effect of the applicable array factor distortion. By use of satellite angle data, navigational data, or both, a predictive angle value of a future arrival angle of a satellite signal may be identified. By developing a correction signal applicable to that future arrival angle, corrections for arriving signals can be applied without reliance on stale values. Corrections may be made to the received satellite signal or may be supplied to the GPS system for corrective use during processing of the received signal.

Abstract: Prior adaptive antenna systems can reduce effects of a jamming or interfering signal by reducing antenna gain in the direction of such signal. However, direction finding capability to enable location of the source of such signal in order to permit corrective or other action has not been available on an economical, low computational basis. Described systems and methods provide correlation matrix estimation to enable direction finding. In an embodiment, a beamformer unit derives an adaptive output signal with use of odd symmetry sequence perturbation signals and weighting signals developed with use of odd symmetry sequence perturbation signals. An extractor unit utilizes even symmetry sequence perturbation signals to process a form of the adaptive output signal, in derivation of output signals representative of a correlation matrix usable for direction finding.

Abstract: Swivel hook units are usable to position a fabric cover, such as a swimming pool cover. A base portion of unitary construction can be attached to a fabric cover via a strap sewn to the cover. A hook member is attached to the base portion via a fastener device which permits rotational displacement of the hook member to accommodate adjustment during installation. A single rivet-type fastener device may be employed. A swivel hook unit may have a flat bottom for placement against a fabric cover without protrusions which would facilitate abrasion of the cover fabric during use. A flexible member to restrain the hook member from unintended disconnection from an eyebolt may include an end section contour configuration to resist lateral displacement of the flexible member relative to the hook member.

Abstract: An automated seal selection, seal design, manufacturing, and post sales system allow a distributor or untrained user to select a replacement seal for a pump. The automated system designs and engineers the seal, whether standard or special, and creates all drawings, documentation, quotations, and other output forms. The automated system initiates selection from inventory or purchasing of materials to be used in the manufacturing operations, creates all manufacturing CNC programs for the components to be manufactured and downloads to CNC from manufacturing equipment. The system allows selection of a seal based upon a seal part number, or selection of a seal based upon the pump into which the seal will be installed and the operating conditions of the pump. The pump may be defined by searching through a database of existing pumps, or may be defined as a new pump if it is not in the pump database.

Abstract: Training sequences, for transmittal with an individual data packet via a wireless communication channel, enable estimation of the channel impulse response (CIR) to provide values usable for correction of multipath and other transmission disturbances with enhanced security and avoidance of complex processing. Training sequences employing several groupings of pseudonoise sequences enable a receiver to derive several observations of the CIR for each data packet received. Averaging of values of the several CIR estimations provides a CIR estimation of increased accuracy usable in determining coefficients to adjust taps of an adaptive equalizer for signal correction for the data of the packet. Training sequences with use of distinct pseudonoise sequences in several individual groupings enhance security, while simplifying processing by avoidance of necessity for multiplication or division of complex functions. Training sequences, systems and methods are described.

Abstract: A GPS antenna with anti-jam capabilities utilizes eight resonant loop radiator elements in a resonant exciter configuration to make available a primary and up to seven auxiliary antenna patterns usable with multi-pattern adaptive processing for anti-jam operation. Antennas as described enable desired radiation characteristics to be provided in a configuration of small size suitable for replacement of existing GPS aircraft antennas which lack anti-jam capabilities, in order to enable reliable GPS reception during airborne operations in the presence of interference or jamming. With enablement of multi-pattern adaptive processing, reduced-gain pattern notches or nulls may be employed to track and reduce the effect of incident signals which would otherwise jam or interfere with reception of GPS signals.

Abstract: Ground based GPS antennas for differential applications may be subject to intentional or other interference signals incident at low elevation angles. Described GPS antenna systems are usable to provide an antenna pattern having a vertically-steerable null. An array of vertically spaced radiator units having omnidirectional azimuth characteristics provides a primary reception pattern. Vertically intermixed radiator units employed on a separate or shared basis provide an auxiliary reception pattern. By subtractively combining the auxiliary pattern with the primary pattern and adjusting the relative signal level of the auxiliary pattern a vertically-steerable pattern null is provided. The antenna system may include an adaptive control system responsive to an antenna output signal to derive a steering signal to adjust the relative signal level of the auxiliary pattern to steer the vertically-steerable null to provide interference suppression. Antenna systems and methods are described.

Abstract: Channel impulse response estimation employs a training sequence to enable correction for multipath and other disturbances affecting a signal during transmission via a digital wireless communication channel. High-speed packet transmission rates, with a training sequence for each packet, are made possible by training sequence construction enabling fast algorithm processing of received signals for impulse response estimation. Upon reception, a Toeplitz-type mathematical representation is constructed based on transmitted and received versions of a training sequence. The Toeplitz-type representation may then be processed by application of fast algorithms, such as Levinson-type algorithms, to determine coefficients representative of the communication channel impulse response. These coefficients, applied to an adaptive equalizer type of filter, enable correction for signal disturbances incurred in transmission. Channel impulse response estimation methods and systems are described.

Abstract: A computer system implements a process for gathering, synthesizing, and analyzing failure and other data relating to a pump, seal or other equipment. Data indicating the current state of the equipment may be gathered and verified prior to a failure occurring so that accurate information is available. After a failure or problem occurs, data about the system and the problem or failure can be methodically gathered to aid in the determination of the root cause of the failure. The data may be synthesized and an analysis performed to determine the cause or causes of the failure or problem. The system may suggest corrective actions and plans for implementing corrective action. Installation instructions, training and safety information can be provided to the user to ensure proper execution of the selected corrective action. A plant reliability manager also may monitor the progress and verify that installation, maintenance and failure correction are performed correctly.

Abstract: An automated seal selection, seal design, manufacturing, and post sales system allows a distributor or untrained user to select a replacement seal for a pump. The automated system designs and engineers the seal, whether standard or special, and creates all drawings, documentation, quotations, and other output forms. The automated system initiates selection from inventory or purchasing of materials to be used in the manufacturing operations, creates all manufacturing CNC programs for the components to be manufactured and downloads to CNC from manufacturing equipment. The system allows selection of a seal based upon a seal part number, or selection of a seal based upon the pump into which the seal will be installed and the operating conditions of the pump. The pump may be defined by searching through a database of existing pumps, or may be defined as a new pump if it is not in the pump database.

Abstract: A compact antenna includes a disk-type radiating element normal to a ground plane section. Each face of the radiating element may have a third-dimensional characteristic (e.g., a convex outer surface.) Dielectric material may be positioned on the ground plane forward of each face of the radiating element. In other configurations, the third-dimensional characteristic and dielectric material features may be used separately in antennas arranged to provide omnidirectional performance over a wide frequency bandwidth. An input/output port may be provided by a coaxial-type connector coupled to the radiating element.

Abstract: Dual-array two-port GPS antenna systems can provide horizon to zenith reception for differential GPS applications. On a single mast, an antenna system may include a lower array of sub-arrays (e.g., fifteen sub-arrays) to provide elevation coverage from horizon up to about 55 degrees elevation and an upper array of sub-arrays (e.g., three sub-arrays) to provide elevation angle coverage from zenith down to about 55 degrees elevation. Each sub-array may be of the same construction including four dipoles positioned at different azimuth locations and configured to provide a progressive-phase-omnidirectional (PPO) azimuth pattern suitable for reception of circularly polarized signals. In a particular embodiment the three sub-arrays of the upper array have PPO azimuth patterns with differing azimuth alignments and differing excitation values to provide a desired elevation angle coverage characteristic.

Abstract: Flat-plate antennas have a compact form by use of a folded path network construction whereby received signals are coupled through a unitary network structure to an adjacent signal processing unit. On a folded path basis, processed signals are then coupled back into the network structure, combined with other received processed signals and then passed out of the network structure to an adjacent signal port. The signal processing unit may provide either amplification, phase shifting, or both. By reciprocal operation a signal to be transmitted may be divided into sub-array components, processed (e.g., power amplified and phase shifted), further divided, and coupled to each slot radiating element (e.g., 256 slots) of an array of slot sub-arrays.

Abstract: Improved punch-through performance is provided for applications such as sum and difference mode processing for IFF and other applications. With an array including a row of elements, difference sidelobe levels are increased relative to sum sidelobe levels by independently controlling relative signal levels of difference mode signals provided from signals received by central elements of the array. By processing signals from central elements independently from processing of signals from outer elements of the array, difference mode signals derived from the central elements may be employed at higher signal levels in order to raise difference mode sidelobe levels to improve punch-through performance. Antenna systems and methods are described.

Abstract: An antenna system to enable satellite communication with a moving vehicle, such as an aircraft, includes an array formed by a group of subarrays. The array is positioned within a cavity and arranged to be mechanically tilted about a horizontal axis-of-rotation to provide elevation scanning of an antenna beam pattern (e.g., 20 to 90 degree elevation scan). The array, with the cavity, is mechanically rotated to provide azimuth scanning of the beam pattern (e.g., 360 degree azimuth scan). Each subarray may be a square flat-plate array having slot-type radiating elements (e.g., simple or crossed-slot elements). Equal excitation of the subarrays for receive or transmit may be provided by a feed configuration at the back of the array.