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 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: 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: 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.

Abstract: An apparatus for controlling an amplitude of a signal generated from a digitized sinusoid of rapidly and widely varying amplitude is described herein. The apparatus includes a two stage gain adjuster which produces a gain adjusted signal, a phase shifter which converts the gain adjusted signal into two gain adjusted output signals separated in phase by 90 degrees, a power estimation unit to estimate the power of the gain adjusted signal, and an adjusting unit to adjust a gain of the gain adjuster according to a power estimate from the power estimation unit and a desired output signal power.

Abstract: A method for reduces the sticking of proof masses in micro-electromechanical systems (MEMS) devices to sense plates in the MEMS device due to acceleration forces to which the MEMS device is subjected. The method includes determining a beginning of acceleration events which would cause proof masses to contact sense plates, reducing sense bias voltages to the sense plates, determining an end of the acceleration event, and increasing sense bias voltages to their former levels.

Abstract: A method for installation alignment of an inertial reference unit (IRU) with vehicle axes when the IRU is installed within the vehicle is provided. The vehicle axes include roll, pitch, and yaw axes. The method includes recording vehicle angular position data including roll and pitch, using an angular position measurement device with the vehicle being in a starting position, recording IRU data including roll and pitch, receiving measured nose plunge data, computing initial roll and pitch misalignment corrections, applying initial roll and pitch misalignment corrections to measured nose plunge data. A nose plunge yaw misalignment is determined using corrected nose plunge data and utilized to adjust the assumed heading reference.

Abstract: A phase processor is disclosed which is configured to receive processed radar return data from a left radar channel, a right radar channel, and an ambiguous radar channel. The phase processor comprises a plurality of phase detectors each with an input and a reference input. The phase detectors are configured to determine a phase difference between radar return data received at the input and radar return data received at the reference input.

Abstract: A filter, includes a first order band pass filter configured to process non-zero amplitude gated radar return samples and process a portion of received zero amplitude return samples. The filter also calculates past filter outputs based on filter outputs generated during previous non-zero gated radar return samples.