Abstract: An apparatus for detecting the presence of ice includes a sensory circuit including a sensor operable to be coupled to a surface exposed to moisture. The sensory circuit is operable to create an electromagnetic standing wave. A heating element is coupled to the surface and a first transmission line. A first source is coupled to the first transmission line and is operable to inject a driving signal into the first transmission line, the driving signal being operable to drive the heating element. A mixing element is coupled to the sensory circuit and first transmission line and is operable to produce a mixed signal from the driving signal and a measure of the standing wave. A comparator is operable to compare at least one characteristic of the mixed signal with reference data for determining the presence of ice contacting the sensor.

Abstract: A method for navigating underwater is disclosed. The method uses a navigation system to project a first velocity measurement along one or more signal beams having a second velocity measurement, where the second velocity measurement is related to at least one of the one or more signal beams. The method determines a position and location of an object associated with the navigation system based on a prediction of at least the second velocity measurement, and the navigation system is adjusted to perform within a prescribed measurement range based on a covariance of the first and second velocity measurements. The performance adjustments made in determining the position and location of the object are operable independent of the navigation system maintaining each of the signal beams due to one or more external environmental conditions.

Abstract: A computer-implementable method of reducing bias instability in a fiber optic gyroscope includes receiving, with a computer, a first data set enabling the computer to generate a model of the gyroscope, including a light source, a photodetector, and a plurality of optical components and fiber sections coupling the light source to the photodetector, and a light signal to be propagated from the light source to the photodetector. The light signal has an associated wavelength spectrum. For each wavelength of the spectrum, the relative lightwave intensity reaching the photodetector is calculated. A signal-wave intensity and a spurious-wave intensity are determined from the calculated relative lightwave intensities. A scale factor is determined from the signal-wave intensity. The spurious-wave intensity is integrated over the wavelength spectrum of the light source to obtain a total spurious-wave intensity. A rate bias error is determined based on the total spurious-wave intensity and the scale factor.

Abstract: Systems and methods for ranging adjustments are provided. In one embodiment, a remote service unit comprises: a transceiver communicatively coupled with a host in a multi-point to point configuration, the transceiver configured to communicate with the host via an OFDM waveform; and a multi-carrier modem coupled to the transceiver and configured to demodulate downstream information data from the OFDM waveform, the multi-carrier modem further configured to modulate upstream information data onto the OFDM waveform. The multi-carrier modem modulates upstream information data onto distinct subcarriers of the OFDM waveform, the multi-carrier modem synchronized with the host so that upstream OFDM signals transmitted by the transceiver and other upstream OFDM signals received at the host unit combine to a unified OFDM waveform. The multi-carrier modem adjusts a round trip path delay between the remote service unit and the host based on a path delay correction received from the host unit.

Abstract: A method and system for autonomous tracking of a mobile target such as a ground vehicle by an unmanned aerial vehicle are provided. The method and system utilize an approach that tracks a mobile ground target by using a ground vehicle model with an ummanned aerial vehicle model, with velocity and acceleration constraints. These real-world constraints ensure that the method is applicable to a general class of unmanned aerial vehicles and ground targets. One or more sensors are employed on the unmanned aerial vehicle, with the sensors having at least one field-of-view sensing cone over the ground. A position and path of the mobile target are monitored through input from the sensors on the unmanned aerial vehicle. The method and system detect and estimate the position and path of the mobile target when the target is inside the field-of-view sensing cone.

Abstract: An electronic computing device including at least one processing unit that implements a specific fault signal upon experiencing an associated fault, a control unit that generates a specific recovery signal upon receiving the fault signal from the at least one processing unit, and at least one input memory unit. The recovery signal initiates specific recovery processes in the at least one processing unit. The input memory buffers input data signals input to the at least one processing unit that experienced the fault during the recovery period.

Abstract: A system and method for communication with an autonomous air vehicle are provided. The system comprises a steerable antenna array including a plurality of directional antenna elements each selectable to receive a video signal from the air vehicle. An antenna control unit is operatively coupled to the antenna elements and includes a magnetometer for determining an orientation for each of the antenna elements. A ground control station is in operative communication with the antenna array and comprises a ground data terminal in operative communication with the antenna control unit, and an operator control unit in operative communication with the data terminal and the antenna control unit. The operator control unit is configured to obtain positions of the air vehicle and the ground control station from the data terminal.

Abstract: An inertial measurement unit comprises a mounting plate with an opening therethrough, and a sensor assembly disposed in the opening of the mounting plate. Upper and lower support shells having shell flanges are attached to upper and lower surfaces of the mounting plate. The upper and lower support shells surround the sensor assembly. A plurality of gas bearing pads each extends through apertures in the upper and lower support shells. Upper and lower gas plenums have plenum flanges attached to the shell flanges of the upper and lower support shells, with the upper and lower gas plenums surrounding the upper and lower support shells. Pressure relief valves are coupled to the plenum flanges of the upper and lower gas plenums. The gas bearing pads and the sensor assembly are separated by a gap when pressurized gas is fed into the upper and lower gas plenums, thereby creating a gas bearing that allows the sensor assembly to be freely suspended and rotated in all directions.

Abstract: A monitoring system and methods are provided for a distributed and recoverable digital control system. The monitoring system generally comprises two independent monitoring planes within the control system. The first monitoring plane is internal to the computing units in the control system, and the second monitoring plane is external to the computing units. The internal first monitoring plane includes two in-line monitors. The first internal monitor is a self-checking, lock-step-processing monitor with integrated rapid recovery capability. The second internal monitor includes one or more reasonableness monitors, which compare actual effector position with commanded effector position. The external second monitor plane includes two monitors. The first external monitor includes a pre-recovery computing monitor, and the second external monitor includes a post recovery computing monitor. Various methods for implementing the monitoring functions are also disclosed.

Abstract: A open access signal distribution system in which a variety of wireless voice, data and other services and applications are supported. The open access systems makes use of a distributed Radio Frequency (RF) distribution network and associated network entities that enable the system operator to employ a wireless infrastructure network that may be easily shared among multiple wireless service providers in a given community. The open access system provides the ability for such operators and service providers to share the infrastructure regardless of the specific RF air interface or other signal formatting and/or managing messaging formats that such operators choose to deploy.

Abstract: An optical device, such as an interference mirror of the type which can be incorporated into ring laser gyros. One embodiment is an interference mirror having at least one layer formed from a matrix of material consisting of ZrO2 and about 2-15 weight percent of Al2O3.

Abstract: An environmentally hardened architecture comprises a hybrid processor, a high speed bus having environmentally-sensitive interfaces, an environmentally hardened bus having environmentally-hardened interfaces, and an environmentally-hardened processor communicatively coupled to an environmentally-sensitive interface of the high speed bus and communicatively coupled to an environmentally-hardened interface of the environmentally hardened bus. The hybrid processor includes an environmentally-hardened processing section and an environmentally-sensitive processing section. At least one environmentally-sensitive interface is configured to pass data to and from the environmentally-sensitive processing section and another environmentally-sensitive interface is configured to pass data to and from the environmentally-hardened processing section of the hybrid processor. An environmentally-hardened interface is configured to pass data to and from the environmentally-hardened processing section of the hybrid processor.

Abstract: A communication system is provided. The communication system comprises a remote transmitter, at least one central unit, and M number of nodes distributed in a coverage area to form a distributed array antenna in order to receive signals from the at least one remote transmitter and retransmit the received signals to the at least one central unit such that when combined the retransmitted signals form a composite signal with a signal-to-noise ratio (SNR) array gain of approximately M and the time to receive the retransmitted signals at the at least one central unit is increased by an inflation rate of approximately M or less.

Abstract: Systems and methods for OFDM tone allocation are provided. In one embodiment, an end-user communication device comprises: a first remote unit for communicating with a host unit using orthogonal frequency division multiplexing (OFDM), the host unit communicatively coupled to a plurality of remote units in a multipoint-to-point configuration, wherein OFDM waveform from distinct remote units of the plurality of remote units combine to a unified OFDM waveform at the host unit. The first remote unit is configured to transmit up to a plurality of tones, the up to a plurality of tones modulated with upstream information using OFDM. The first remote unit is configured to determine when bandwidth is needed for upstream transmission to the host unit. The first remote unit is configured to transmit a request for bandwidth to the host unit on a first tone of the plurality of tones, wherein access to the first tone is contention-based.

Abstract: Apparatus is provided for a fiber optic gyro. The fiber optic gyro includes a ring resonator having first and second counter-propagating directions. The ring resonator includes a coil having an axis and an optical fiber having a hollow core. The ring resonator is configured to produce a first resonance frequency when a first light beam circulates through the hollow core in the first counter-propagating direction and produce a second resonance frequency when a second light beam circulates through the hollow core in the second counter-propagating direction. A difference between the resonance frequencies indicates a rotation rate of the fiber optic gyro about the axis.

Abstract: Embodiments of the present invention pertain generally to methods and systems of processing a global positioning satellite (GPS) signal. More particularly, embodiments of the present invention provide an improved discriminator function that utilizes the early, prompt, and late correlator values. For example, the improved discriminator function may be normalized based on all three of the early, prompt, and late correlator values. The improved discriminator function behaves linearly across a prescribed region whose width depends on the separation between correlators.

Abstract: A method and system for context sensitive navigation of an aircraft is provided. The method comprises obtaining data for use at takeoff, enroute, or at a destination, and interpreting the data to infer conditions during takeoff, enroute, or at the destination. One or more viable flight plans are determined based on the conditions during takeoff, enroute, or at the destination. The one or more viable flight plans are then presented to a pilot for optional selection. When there is more than one viable flight plan, a prioritized selectable list of flight plans is presented to the pilot.

Abstract: Message translation systems and methods are provided. In one embodiment, a method for translating messages comprises reading a first sequence of one or more message elements from a first interface, wherein the message elements are structured based on a first protocol; converging on a message mapping node based on the first sequence of one or more message elements, wherein the message mapping node is defined by a protocol metadata schema; performing one or more conversion operations on the first sequence of one or more message elements to construct a second sequence of one or more message elements, wherein the one or more conversion operations are based on the message mapping node; and writing the second sequence of one or more message elements to a second interface.

Abstract: A method for assembling a hermetically sealed package to contain a MEMS die and the hermetically sealed package are presented. The method includes selectively applying a glass mixture to a dome. The dome is heated to a first temperature sufficient to flow the glass mixture. The dome is pressed into contact with a carrier containing the MEMS device, the pressing being maintained at a pressure and for a temporal interval sufficient to flow the glass mixture onto the carrier. The dome is cooled while maintaining contact with the carrier, to a second temperature sufficient to allow the glass mixture to harden into a glass frit thereby to seal the carrier to the dome. The glass frit has a seal width.