Abstract: In some examples, a system is configured to mount on a first vehicle. The system include an antenna configured to transmit a first surveillance message by forming an omni-directional beam. The antenna is also configured to receive a second surveillance message from a second vehicle during a first time period. The antenna is further configured to receive a third surveillance message from a third vehicle during a second time period, where the first and second time periods at least partially overlap in time. The system also includes processing circuitry configured to demodulate the second surveillance message by forming a first beam and demodulate the third surveillance message by forming a second beam. The second beam is different than the first beam, and the first beam is simultaneous with the second beam.

Abstract: In some examples, a system is configured to mount on a first vehicle. The system include an antenna configured to transmit a first surveillance message by forming an omni-directional beam. The antenna is also configured to receive a second surveillance message from a second vehicle during a first time period. The antenna is further configured to receive a third surveillance message from a third vehicle during a second time period, where the first and second time periods at least partially overlap in time. The system also includes processing circuitry configured to demodulate the second surveillance message by forming a first beam and demodulate the third surveillance message by forming a second beam. The second beam is different than the first beam, and the first beam is simultaneous with the second beam.

Abstract: Described herein is a calibration circuit for a multiple element antenna with two or more antenna transmit and receive elements. In some examples the multi-element antenna may also include a beamforming network that combine the multiple antenna radiating element inputs and outputs with controlled phase and amplitude relationships such that spatial beams can be formed by varying the phase and amplitudes of two or more signals applied to antenna input ports for the antenna. The calibration circuit of this disclosure may be used to obtain data to determine phase and amplitude offsets induced by the combined transmission elements, and any phase and amplitude offsets induced by the transmitter or receiver circuitry. The determined phase and amplitude offsets may then be removed from received signal measurements and compensated for in transmit signal generation.

Abstract: Described herein is a calibration circuit for a multiple element antenna with two or more antenna transmit and receive elements. In some examples the multi-element antenna may also include a beamforming network that combine the multiple antenna radiating element inputs and outputs with controlled phase and amplitude relationships such that spatial beams can be formed by varying the phase and amplitudes of two or more signals applied to antenna input ports for the antenna. The calibration circuit of this disclosure may be used to obtain data to determine phase and amplitude offsets induced by the combined transmission elements, and any phase and amplitude offsets induced by the transmitter or receiver circuitry. The determined phase and amplitude offsets may then be removed from received signal measurements and compensated for in transmit signal generation.

Abstract: Systems and methods for calculating coherent bearing that allow one to reduce the number of TCAS antenna elements. In one embodiment, the bearing calculation takes into account signal-to-noise ratio (SNR) difference experienced from top and bottom antennas mounted on a vehicle.

Abstract: Systems and methods for improving bearing availability and accuracy in a traffic collision-avoidance system (TCAS). In an exemplary method, if only a single phase-difference value is received for one of two two-element antennas, a processor determines an expected maximum antenna element phase-difference value for the elements of the two-element antenna that did not receive a phase-difference value for a target signal source; estimates a phase-difference value for the two-element antenna that did not include a phase-difference value, based on the expected maximum antenna element phase-difference value and a previously determined predicted bearing value; and calculates bearing based on the estimated phase-difference value and a phase-difference value received from the other two-element antenna.

Abstract: Systems and methods for improving bearing initialization for a pair of two-element antennas. An exemplary system includes two-element antennas mounted on the bottom and top of an aircraft fuselage, an output device, and a processing device. The processing device receives phase-difference information based on phase of signals received at each element of a two-element antenna, determines if the received phase-difference information is within a predefined low-confidence region, and initializes bearing if the phase-difference information is not within the low-confidence region or the phase-difference information from a predefined number of consecutively received signals meets a predefined consistency requirement.

Abstract: A two-element array antenna system includes a first antenna element and a second antenna element. A transmitting, receiving, and processing (TRP) system is coupled to the first and second antenna elements via, respectively, a single first transmission element and a single second transmission element. The first and second transmission elements have respective transmit-path and receive-path functionality. The TRP system is configured to determine an amplitude offset and phase offset associated with the transmit-path functionality of the first and second transmission elements, and, based on data obtained during the determination of amplitude offset and phase offset associated with the transmit-path functionality of the first and second transmission elements, determine an amplitude offset and phase offset associated with the receive-path functionality of the first and second transmission elements.

Abstract: Systems and methods for improving bearing availability and accuracy in a traffic collision-avoidance system (TCAS). In an exemplary method, if only a single phase-difference value is received for one of two two-element antennas, a processor determines an expected maximum antenna element phase-difference value for the elements of the two-element antenna that did not receive a phase-difference value for a target signal source; estimates a phase-difference value for the two-element antenna that did not include a phase-difference value, based on the expected maximum antenna element phase-difference value and a previously determined predicted bearing value; and calculates bearing based on the estimated phase-difference value and a phase-difference value received from the other two-element antenna.

Abstract: Systems and methods for improving bearing initialization for a pair of two-element antennas. An exemplary system includes two-element antennas mounted on the bottom and top of an aircraft fuselage, an output device, and a processing device. The processing device receives phase-difference information based on phase of signals received at each element of a two-element antenna, determines if the received phase-difference information is within a predefined low-confidence region, and initializes bearing if the phase-difference information is not within the low-confidence region or the phase-difference information from a predefined number of consecutively received signals meets a predefined consistency requirement.

Abstract: Systems and methods for calculating coherent bearing that allow one to reduce the number of TCAS antenna elements. In one embodiment, the bearing calculation takes into account signal-to-noise ratio (SNR) difference experienced from top and bottom antennas mounted on a vehicle.

Abstract: A two-element array antenna system includes a first antenna element and a second antenna element. A transmitting, receiving, and processing (TRP) system is coupled to the first and second antenna elements via, respectively, a single first transmission element and a single second transmission element. The first and second transmission elements have respective transmit-path and receive-path functionality. The TRP system is configured to determine an amplitude offset and phase offset associated with the transmit-path functionality of the first and second transmission elements, and, based on data obtained during the determination of amplitude offset and phase offset associated with the transmit-path functionality of the first and second transmission elements, determine an amplitude offset and phase offset associated with the receive-path functionality of the first and second transmission elements.