Abstract: A low range altimeter (LRA) may include a transmitter, a receiver, at least one antenna, an active leakage cancellation circuit, and a microcontroller unit (MCU). The transmitter may be configured to transmit a first signal (or transmitted signal) via the at least one antenna. The receiver may be configured to receive a second signal (or received signal) via the at least one antenna. The active leakage cancellation circuit may be configured to receive a portion of the transmitted signal from the transmitter, and may be configured to inject the portion of the transmitted signal into the receiver after an adjustment of the portion of the transmitted signal to reduce leakage observed in the received signal. The MCU may be coupled to the transmitter and the receiver, and may be configured to adjust the portion of the portion of the transmitted signal.

Abstract: A transmitter for an aircraft is disclosed. The transmitter comprises a first channel configured to transmit first radio frequency (RF) signals in a first direction and a second channel configured to transmit second RF signals in a second direction. A branchline coupler is communicatively coupled to the first channel and the second channel. The branchline coupler comprises one or more quarter wave transformers and a set of PIN diode switches configured to have a high impedance responsive to the transmitter being in an amplitude-based mode and a low impedance responsive to the transmitter being in a phase-based mode.

Abstract: A low range altimeter (LRA) may include a transmitter, a receiver, at least one antenna, an active leakage cancellation circuit, and a microcontroller unit (MCU). The transmitter may be configured to transmit a first signal (or transmitted signal) via the at least one antenna. The receiver may be configured to receive a second signal (or received signal) via the at least one antenna. The active leakage cancellation circuit may be configured to receive a portion of the transmitted signal from the transmitter, and may be configured to inject the portion of the transmitted signal into the receiver after an adjustment of the portion of the transmitted signal to reduce leakage observed in the received signal. The MCU may be coupled to the transmitter and the receiver, and may be configured to adjust the portion of the portion of the transmitted signal.

Abstract: An altimeter apparatus for an aircraft includes an altimeter circuit and can use a method of determining altitude. The method includes receiving a first signal in a first band via a first receive antenna, and receiving a second signal in a second band via a second receive antenna. The first band is a C-Band and the second band is at least one of a W-Band, Ku-Band, Ka-Band, V-band, or K-Band. The method also includes providing an altitude in response to the first signal or the second signal.

Abstract: An altimeter apparatus for external fuselage mounting for an aircraft includes an altimeter circuit and a chassis. The altimeter circuit is coupled to an antenna system. The altimeter circuit is configured to generate a first signal and transmit the first signal via the antenna system, receive a second signal via the antenna system, wherein the second signal is a reflected version of the first signal, and determine an altitude based on the first and second signals. The chassis is configured to contain the altimeter circuit and the antenna system, wherein the chassis is connected to a fuselage of the aircraft and is located outside of the aircraft.

Abstract: The present disclosure is directed to low range altimeter (LRA) antenna implementations that are resistant to signal degradation under critical weather conditions. An altimeter may include a first antenna communicatively coupled to a transmitter configured to transmit a ranging signal to a surface. The altimeter may further include a second antenna communicatively coupled to a receiver configured to receive at least a portion of the ranging signal reflected from the surface. Each of the first (transmitting) antenna and the second (receiving) antenna may include a driven element and at least one parasitic director element. In some embodiments, at least a portion of an aircraft surface may function as a parasitic reflector element in accordance with a Yagi-Uda array antenna topology.

Abstract: A multi-function avionics system that includes, but is not limited to, a combined traffic collision avoidance system (TCAS) and directional measuring equipment (DME) system that utilizes a multi-function directional antenna for both functions. The multi-function system utilizes the same directional antenna for TCAS and DME functions, which typically utilize the same communication frequency band. The multi-function antenna may include four antenna elements that discriminate the direction of the DME ground station squitter. The DME system establishes a bearing to the ground station from the squitter and uses this information to determine which directional beam to use for the DME interrogation. Directional DME interrogation reduces the power requirements relative to that required for omni-directional DME interrogation. The integration of DME and TCAS enables the removal of antennas and feeder cables from the aircraft, saving weight, drag and cost.

Abstract: A low drag TCAS antenna includes a plurality of broadband antenna elements in a housing having at least three fins. L band radios in the aircraft may utilize the broadband antenna elements, thereby reducing power consumption, cost and aerodynamic inefficiency due to a plurality of antennas protruding from the aircraft.

Abstract: A traffic collision avoidance system (TCAS) based navigation system including a TCAS equipped with a directional antenna, the TCAS configured to generate a RF transmission pattern at a selected frequency, the transmission pattern including a plurality of directional beams, receive a plurality of RF signals reflected from the ground across a selected frequency band, the selected frequency band including the selected frequency, and measure frequency differences between one or more beams of the plurality of RF beams and one or more beams of the plurality of RF signals reflected from the ground, and a computing systems in communication with the TCAS, the computing system configured to calculate a ground speed of the aircraft utilizing the measured frequency differences, calculate a drift angle of the aircraft utilizing the measured plurality of frequency differences, receive a heading reference of the aircraft, and determine an aircraft navigation parameter of the aircraft.

Abstract: A distance measuring, device including a lookup table storing values to calibrate a Class AB amplifier to produce a pulse pair with the desired characteristics. The distance measuring device analyzes the characteristics of the output signal and recursively adapts the values stored in a lookup table to force the output the power amplifier to meet the required performance characteristics.

Abstract: A first linearly polarized component of a signal is received. A second linearly polarized component of a signal is received, wherein the second linearly polarized signal component of a signal is orthogonal to the first linearly polarized component of a signal. The first linearly polarized component of a signal and the second linearly polarized component of a signal are down-converted to a lower frequency. A polarization correction is performed on the down-converted linearly polarized components.

Abstract: A method and apparatus for utilizing the distortion generated within a portion of a balanced amplifier to cancel the distortion generated within the whole balanced amplifier. Samples of the signal and distortion from part of the balanced amplifier are combined with a reference signal such that the two signals destructively combine leaving the distortion from the sampled part of the balanced amplifier. The gain and phase of the distortion is then adjusted so that when it is coupled into the input of the other part of the balanced amplifier the distortion generated by both parts of the balanced amplifier are cancelled.

Abstract: A method and apparatus for utilizing the distortion generated within a portion of a balanced amplifier to cancel the distortion generated within the whole balanced amplifier. Samples of the signal and distortion from part of the balanced amplifier are combined with a reference signal such that the two signals destructively combine leaving the distortion from the sampled part of the balanced amplifier. The gain and phase of the distortion is then adjusted so that when it is coupled into the input of the other part of the balanced amplifier the distortion generated by both parts of the balanced amplifier are cancelled.