Abstract: Apparatus and methods of determining altitude information with a radar receiver with quadrature detection is provided. A method includes generating baseband frames. An oscillator signal is created within each of the baseband frames. A return of the oscillator signal is coupled to a first input of a mixer. Moreover, the oscillator signal is coupled to a second input of the mixer. A phase of the oscillator signal is selectively changed between two or more distinct values. Timing of the change being based at least in part on a baseband frame timing of the generated baseband frames. Samples of an output of the mixer are selectively collected further based at least in part on the baseband frame timing. The collected samples are processed to compute altitude information.

Abstract: Systems and methods of operating an interference prevention system in a radar altimeter are provided. A method includes generating integer values with at least one pseudorandom noise sequence generator. The generated integer values are used as indexes to select at least one of start frequencies and stop frequencies from at least one frequency table for frequency modulated continuous wave (FMCW) ramps for a generated radar signal. The selected at least one of the start frequencies and the stop frequencies is provided to a frequency synthesizer. The at least one of start frequencies and the stop frequencies are used in generating transmit frames of the radar signal with the frequency synthesizer.

Abstract: Apparatus and methods of determining altitude information with a radar receiver with quadrature detection is provided. A method includes generating baseband frames. An oscillator signal is created within each of the baseband frames. A return of the oscillator signal is coupled to a first input of a mixer. Moreover, the oscillator signal is coupled to a second input of the mixer. A phase of the oscillator signal is selectively changed between two or more distinct values. Timing of the change being based at least in part on a baseband frame timing of the generated baseband frames. Samples of an output of the mixer are selectively collected further based at least in part on the baseband frame timing. The collected samples are processed to compute altitude information.

Abstract: Systems and methods of operating an interference prevention system in a radar altimeter are provided. A method includes generating integer values with at least one pseudorandom noise sequence generator. The generated integer values are used as indexes to select at least one of start frequencies and stop frequencies from at least one frequency table for frequency modulated continuous wave (FMCW) ramps for a generated radar signal. The selected at least one of the start frequencies and the stop frequencies is provided to a frequency synthesizer. The at least one of start frequencies and the stop frequencies are used in generating transmit frames of the radar signal with the frequency synthesizer.

Abstract: A method and system for estimating velocity of an aircraft is provided. The method comprises transmitting a beam toward a surface from the aircraft using a Doppler beam sharpened radar altimeter, receiving a plurality of reflected signals that correspond to portions of the transmitted beam that are reflected by the surface, and forming a plurality of Doppler beams by filtering the received signals. A complex-valued array of range bin is computed with respect to frequency of the Doppler beams from at least one antenna aperture of the radar altimeter, and a range for each of the Doppler beams is estimated. A velocity vector magnitude for the aircraft is estimated by a curve fit of the range with respect to the frequency of the Doppler beams.

Abstract: Systems and methods for measuring velocity with a radar altimeter are provided. In at least one embodiment a method for measuring velocity magnitude of a platform in relation to a surface comprises transmitting a radar beam, wherein the radar beam is aimed toward a surface; receiving a plurality of reflected signals, wherein the plurality of reflected signals correspond to portions of the transmitted radar beam that are reflected by a plurality of portions of the surface; and applying Doppler filtering to the plurality of signals to form at least one Doppler beam. The method also comprises identifying range measurements within each Doppler beam in the at least one Doppler beam; and calculating the velocity magnitude based on the range measurements of the at least one Doppler beam.

Abstract: A method and system for estimating velocity of an aircraft is provided. The method comprises transmitting a beam toward a surface from the aircraft using a Doppler beam sharpened radar altimeter, receiving a plurality of reflected signals that correspond to portions of the transmitted beam that are reflected by the surface, and forming a plurality of Doppler beams by filtering the received signals. A complex-valued array of range bin is computed with respect to frequency of the Doppler beams from at least one antenna aperture of the radar altimeter, and a range for each of the Doppler beams is estimated. A velocity vector magnitude for the aircraft is estimated by a curve fit of the range with respect to the frequency of the Doppler beams.

Abstract: Systems and methods for using velocity measurements to adjust Doppler filter bandwidth are provided herein. In certain embodiments, a method for adjusting bandwidth for at least one Doppler filter in a Doppler beam sharpened radar altimeter comprises receiving a velocity measurement; adjusting the bandwidth of the at least one Doppler filter based on the velocity measurement; and transmitting a radar beam, wherein the radar beam is aimed toward a surface. The method further comprises receiving at least one reflected signal, wherein the at least one reflected signal is a reflection of the radar beam being reflected off of at least one portion of the surface; and filtering the at least one reflected signal with the at least one Doppler filter to form at least one Doppler beam.

Abstract: Systems and methods for using velocity measurements to adjust Doppler filter bandwidth are provided herein. In certain embodiments, a method for adjusting bandwidth for at least one Doppler filter in a Doppler beam sharpened radar altimeter comprises receiving a velocity measurement; adjusting the bandwidth of the at least one Doppler filter based on the velocity measurement; and transmitting a radar beam, wherein the radar beam is aimed toward a surface. The method further comprises receiving at least one reflected signal, wherein the at least one reflected signal is a reflection of the radar beam being reflected off of at least one portion of the surface; and filtering the at least one reflected signal with the at least one Doppler filter to form at least one Doppler beam.

Abstract: Systems and methods for load aware radar altimeters are provided. In one embodiment, a method for a load aware radar altimeter comprises: transmitting from a radar altimeter on an aircraft at least one RF radar pulse having a frequency of f0; receiving a first return RF signal from a signal modifying target device attached to a load suspended below the aircraft, wherein the first return signal is a modified version of the at least one RF radar pulse; calculating a range from the aircraft to the signal modifying target device as a function of a propagation delay between transmitting the at least one RF radar pulse and receiving the first return RF signal; and desensitizing the radar altimeter to return RF signals having a frequency of f0 within a load window calculated as a function of the range from the aircraft to the signal modifying target device.

Abstract: Systems and methods for measuring velocity with a radar altimeter are provided. In at least one embodiment a method for measuring velocity magnitude of a platform in relation to a surface comprises transmitting a radar beam, wherein the radar beam is aimed toward a surface; receiving a plurality of reflected signals, wherein the plurality of reflected signals correspond to portions of the transmitted radar beam that are reflected by a plurality of portions of the surface; and applying Doppler filtering to the plurality of signals to form at least one Doppler beam. The method also comprises identifying range measurements within each Doppler beam in the at least one Doppler beam; and calculating the velocity magnitude based on the range measurements of the at least one Doppler beam.

Abstract: A method for distinguishing a signal of interest from one or more interference signals in a received analog signal comprises receiving an analog signal at a radio front end, and transmitting the received analog signal to an analog-to-digital converter to sample data in the received analog signal and output a digital signal. A sub-channel Fast Fourier Transform (FFT) is performed on the digital signal, and sub-channel FFT bin magnitudes are averaged over a set period of time to determine a shape of the received signal. The shape of the received signal is compared to one or more signal reference patterns by computing a metric for the shape of the received signal, and computing a metric for the one more signal reference patterns. The computed metrics are then compared to a predetermined threshold value to determine the presence, or lack thereof, of a signal of interest in the received signal.

Abstract: A method for distinguishing a signal of interest from one or more interference signals in a received analog signal comprises receiving an analog signal at a radio front end, and transmitting the received analog signal to an analog-to-digital converter to sample data in the received analog signal and output a digital signal. A sub-channel Fast Fourier Transform (FFT) is performed on the digital signal, and sub-channel FFT bin magnitudes are averaged over a set period of time to determine a shape of the received signal. The shape of the received signal is compared to one or more signal reference patterns by computing a metric for the shape of the received signal, and computing a metric for the one more signal reference patterns. The computed metrics are then compared to a predetermined threshold value to determine the presence, or lack thereof, of a signal of interest in the received signal.

Abstract: A method is disclosed for operating an engine with a first cylinder providing a net flow of gases from the intake to the exhaust while combusting; and a second cylinder providing a net flow of gases from the exhaust to the intake. Both the first and second cylinders may carry out combustion during such operation.

Abstract: A method for operating a multi-stroke homogeneous charge compression ignition engine is described. The method includes late intake valve opening (LIVO) and also cycling air and fuel charge from the cylinder back into the intake manifold during a compression stroke to mix the air and fuel charge for later reintroduction and combustion.

Abstract: A method is disclosed for operating an engine with a first cylinder providing a net flow of gases from the intake to the exhaust while combusting; and a second cylinder providing a net flow of gases from the exhaust to the intake. Both the first and second cylinders may carry out combustion during such operation.

Abstract: A method of operating an engine is provided. The engine includes operating a cylinder with net exhaust flow from the exhaust manifold, through the cylinder, to the intake manifold. Concurrently, another cylinder may operate to carry out combustion with net flow from the intake to the exhaust. In this way, exhaust in the intake manifold may be adjusted by varying valve operation of the first cylinder.

Abstract: A system for controlling a multiple cylinder internal combustion engine having a plurality of cylinders with electronically actuated valves (EVA) is presented. The system is designed to improve the torque delivery of an EVA engine that operates a portion of cylinders in an HCCI combustion mode.

Abstract: A method is disclosed for operating an engine with a first cylinder providing a net flow of gases from the intake to the exhaust while combusting; and a second cylinder providing a net flow of gases from the exhaust to the intake. Both the first and second cylinders may carry out combustion during such operation.

Abstract: Magnetically responsive particles can include two or more magnetically responsive layers (“MRL”). As such, the particles can have the following: a polymeric core; a first magnetically responsive layer (“MRL”) on the core; a first polymeric layer bound to the first MRL; a second MRL layer bound to the first polymeric layer; and a second polymeric layer bound to the second MRL. The particles can have a faster magnetic response time compared to a similar particle having only a single MRL, which can be at least 25% faster. Also, the particle can have a magnetic squareness of less than about 0.1. Preferably, the particle can have negligible residual magnetism after being exposed to a magnetic field sufficient for the particle to respond thereto. Further, the particle can be colloidally stable in water at concentrations from about 0.1 to 10 grams of particle per 100 milliliters of water.