Abstract: A two-axis magnetic field sensor includes a substrate, a first sensor having at least one magnetoresistive element formed of GMR material on the substrate has a free layer having an easy axis of effective anisotropy field in a first direction. The first sensor is sensitive to magnetic field components perpendicular to the first direction. A current is caused to flow through the first sensor and variations in the resistivity of the first sensor due to the first magnetic field components are sensed. A second sensor having at least one magnetoresistive element formed of GMR material on the substrate has a free layer having an easy axis of effective anisotropy field in a direction substantially perpendicular to the first direction. The second sensor is sensitive to second magnetic field components perpendicular to its easy axis of effective anisotropy. A current is caused to flow through the second sensor and variations in the resistivity of the second sensor due to second magnetic field components are sensed.

Abstract: An integrated magnetic field sensing device includes at least two magnetoresistive elements which are biased in a first direction by an integral conductor and are sensitive to magnetic field components in a direction perpendicular to the first direction. The sensitivity of the device to a magnetic field is adjustable and is related to the level of the bias current. In a current measuring application, two of the magnetic field sensing devices are mounted on opposite sides of and perpendicular to a conductor carrying a current to be measured. In a portable current measuring apparatus, two of the magnetic field sensors are mounted in a housing that assists in locating the magnetic field sensors relative to the conductor carrying the current to be measured.

Abstract: A method for determining heave and heave rate for a vessel is described. The vessel includes an inertial navigation system (INS), and sensors for the INS being located at a point A of the vessel, the vessel having a zero heave reference point B, and the described method provides heave and heave rate at a point C of the vessel. The method includes determining reference coordinates for points A, B, and C of the vessel, generating a velocity signal representative of a velocity at a point on the vessel, generating a heave rate signal based upon the velocity signal, and generating a heave based upon the heave rate signal.

Abstract: A unit is configured to provide acceleration, velocity, and position information for one or more points on a vehicle. The unit includes an integrated global positioning satellite system (GPS)/inertial navigation system (INS) and at least one remote velocity sensor. The remote velocity sensors include three orthogonal accelerometers and a digital signal processor configured to receive signals from the accelerometers. The remote velocity sensors are mounted at points on the vehicle where acceleration, velocity and position are to be determined. Data from the sensors is slaved to data from the integrated GPS/INS, and the unit is configured to transform data from the sensors to a navigation frame utilizing a sensor frame to navigation frame attitude matrix.

Abstract: A method for determining compensation coefficients for accelerometers which exhibit bias transients is described. The method comprises estimating bias accumulation from measured accelerometer outputs, determining a corrected accelerometer output, and determining the compensation coefficients for the accelerometer.

Abstract: A method for reducing effects of common mode oscillations between two respective proof masses in micro-electromechanical systems (MEMS) devices is described. The MEMS devices also include a motor pickoff comb, a sense plate, and a motor drive comb for each proof mass. The method includes amplifying signals received from respective motor pickoff combs, inverting the amplified signal from one of the motor pickoff combs, and generating a difference signal between the inverted, amplified signal from one pickoff comb, and the non-inverted, amplified signal from the other pickoff comb. The method also includes inputting the difference signal into a control loop and generating motor drive signals for respective motor drive combs with the control loop.

Abstract: A method for testing radar system performance is disclosed which utilizes radar data test points in a radar data file. The method includes interpolating GPS data from a flight test to provide a GPS data point for every radar data test point, generating body coordinate values for every point in a corresponding digital elevation map (DEM) file using the interpolated GPS data, and applying a bounding function around at least a portion of the body coordinate values generated from the DEM file at a given time. The method also includes determining which body coordinate value generated from the DEM file is closest a current GPS data point for the given time and comparing the determined body coordinate value to the radar data test points at the given time.

Abstract: A method for synchronizing nodes in a network is described that utilizes an interactive convergence technique. The technique utilizes communications protocol IEEE 1394 to broadcast each node's clock value to the other nodes in the network. Each node applies a voting algorithm to the set of broadcasted clock values to determine a voted clock value and each node's clock is set to that voted clock value. When a node's clock value is close in value to another node, those nodes are considered to be synchronized. The set of clock values to be used to determine the voted clock value consists of those nodes that are synchronized. The technique is implemented on hardware separate from the node's hardware and can be implemented on a field programmable gate array.

Abstract: A method for controlling bow in wafers which utilize doped layers is described. The method includes depositing a silicon-germanium layer onto a substrate, depositing an undoped buffer layer onto the silicon-germanium layer, and depositing a silicon-baron layer onto the undoped layer.

Abstract: Methods and apparatus for electrostatically pumping fluids without passing the fluids through the electric field of the pump are contemplated. Electrostatic forces are preferably used to move the diaphragms in one direction, while elastic and/or other restorative forces are used to move the diaphragms back to their original un-activated positions. In some embodiments, this may allow fluid to be pumped without passing the fluid between actuating electrodes. This may be particularly useful when the fluids have dielectric, conductive, polar or other qualities that may affect traditional electrostatic pump performance. Pumps having various elementary cells are contemplated, including two-celled pumps disposed within a single chamber and pumps having greater numbers of cells wherein each cell is disposed within a different chamber.

Abstract: An antenna is described which includes first, second, and third conductive layers and a first and second laminate to separate the layers. The laminates are configured with plated through holes to provide contact between the first and third layers, the holes defining antenna cavities, the second conductive layers being the antenna. A plurality of slots in the first conductive layer align within the defined antenna cavities, further defining the antenna cavities for the second conductive layer.

Abstract: A method for simulating a Doppler signal under stationary conditions is described. The method includes sampling a radar return signal at an integer multiple of the return signal frequency plus a fraction of the return signal period and generating a base band signal from the samples.

Abstract: A radar altimeter is described which includes a transmitter for transmitting a radar signal, a receiver for receiving the reflected radar signal, and at least one antenna coupled to one or both of the transmitter and receiver. The altimeter also includes a forward facing millimeter wave (MMW) antenna configured to move in a scanning motion and a frequency up/down converter coupled to the MMW antenna, the transmitter, and the receiver, and a radar signal processor. The converter up converts a frequency received from the transmitter to a MMW frequency for transmission through the MMW antenna, and down converts frequencies received to a radar frequency which are output to the receiver. The radar signal processor controls scanning motion of the MMW antenna, processes signals received at the antenna for a portion of the scanning motion, and processes signals received at the MMW antenna for other portions of the scanning motion.

Abstract: Methods for attaching two wafers are presented along with devices resulting from such methods. In one illustrative embodiment, a first wafer is provided having pillars for conducting an electric signal. The wafer also includes an electronic device such as an inductor or capacitor that may in some instances consume relatively large amounts of space. The first wafer is bonded to a second wafer so that a circuit on the second wafer may be electrically connected to the electronic device of the first wafer.

Abstract: A method of determining a target location from a vehicle is described. The method includes identifying the target utilizing a video system, determining an angular location vector to the target with respect to the vehicle, determining a position of the vehicle utilizing a digital terrain elevation map and precision radar altimeter, calculating a location where the angular location vector would intersect with the digital terrain elevation map, and generating a target position based on vehicle position and the location of the intersection of the angular location vector and digital terrain elevation map.

Abstract: A method for testing a radar system utilizing flight test radar data is described. The method includes time synchronizing measured radar data with a GPS based time marker, storing at least a portion of the time synchronized radar data, storing the GPS data, processing the stored GPS data to correspond with a physical position of an antenna which received the radar data, providing a radar model, and comparing the processed radar model data to the stored radar data.

Abstract: A method for reducing effects of terrain return fading due to summation of out of phase radar returns in determining locations of radar targets is described. The method comprises determining an interferometric angle, &PHgr;, to a radar target based on at least one radar return and filtering the interferometric angle, &PHgr;, by adjusting an effect of terrain features contributing to the interferometric angle, &PHgr;, proportionally to a degree of radar return fading resulting from the terrain features of the radar targets. A corrected interferometric angle, &PHgr;out., is then provided, based at least in part on the filtering.

Abstract: An in-phase/quadrature component (IQ) mixer is configured to reject returns from a negative doppler shift swath in order to mitigate corruption of returns of a positive doppler shift swath. The mixer includes a sample delay element which produces a quadrature component from the in-phase component of an input signal. Further included are a plurality of mixer elements, a plurality of low pass filters, a plurality of decimators, and a plurality of all pass filters which act upon both the in-phase and quadrature components of the input signal. Also, a subtraction element is included which is configured to subtract the filtered and down sampled quadrature component from the filtered and down sampled in-phase component.

Abstract: A method for suppressing ground return radar fading in a radar altimeter is described. The method includes providing a radar gate width which corresponds to an area that is smaller than an antenna illumination area being impinged by transmissions of the radar altimeter, dithering the radar gate viewing area within the antenna illumination area being impinged by transmissions of the radar altimeter, and taking radar return samples with the radar altimeter.

Abstract: An apparatus for calibrating a radar altimeter is described. The altimeter provides an angle to a target based on radar energy received at right, left, and ambiguous antennas. The apparatus comprises a turntable on which the radar is mounted, a turntable controller which controls positioning of the radar altimeter, a radar energy source receiving transmit signals from the radar altimeter, a reflector, and a calibration unit. The reflector reflects and collimates radar energy from the radar source towards the radar altimeter. The calibration unit receives an angle from the controller indicative of a position of the radar altimeter with respect to the collimated radar energy and a measured angle from the radar altimeter. The calibration unit calculates a correction based on differences between the angle received from the turntable and the measured angle received from the altimeter and provides the calibration correction to the altimeter.