Abstract: An electronic system with real-time fault detection is provided. In one embodiment, the system includes analog circuitry, having a first input coupled to receive an input signal and a second input coupled to receive a test signal. The test signal is at an edge of a selected band that contains the input signal. The test signal is used to identify faults in the electronic system during operation of the electronic system. The electronic system further includes an analog to digital (A/D) converter coupled to an output of the analog circuitry. The A/D converter generates digitized spectrum. Digital circuitry is coupled to the output of the A/D converter. The digital circuitry processes the input signal from the band to provide an output for the system and processes the test signal to detect faults in the analog circuitry, the digital circuitry and the A/D converter.

Abstract: Systems and methods for receiving ADS-B messages in environments where multipath propagation corrupts the messages or blocks the reception of the messages. An exemplary system combines RF signal processing and digital signal processing techniques to make it possible to receive ADS-B messages in the presence of multipath reflections from nearby structures and/or farther out structures. The system uses an array of horizontally spaced antennas. The RF signals from the antennas are combined by the receiver so as to form a set of beams with different azimuth antenna patterns to increase the probability that the multipath does not combine destructively with the line-of-sight path in at least one of the beams. This effectively removes multipath reflections where the delay of the multipath relative to the line-of-sight path is less than 100-200 nanoseconds. The system is also configured to remove multipath reflections with greater delays relative to the line-of-sight path.

Abstract: One embodiment is directed towards an RF receiver for receiving a pulse-position modulated signal transmitted with a 1090 MHz ADS-B transmitter, wherein the pulse-position modulated signal is preceded by a preamble of 4 pulses that conform to an ADS-B protocol. The receiver can filter a digital sample stream with a filter matched to pulses in an earlier half of an expected preamble sequence to produce a first matched filter output sample stream. The receiver can also filter the digital sample stream with a filter matched to a pulses in a latter half of the expected preamble sequence to produce a second matched filter output sample stream. The receiver can determine that a sequence of pulses match the expected preamble sequence based on when the first matched filter output sample stream and the second matched filter output sample stream are above a minimum trigger level at the same time.

Abstract: A wideband multi-channel receiver comprises an antenna configured to receive a radio frequency band. A band-pass filter is in signal communication with the antenna, and a low-noise amplifier is in signal communication with the band-pass filter. A mixer is in signal communication with the low-noise amplifier and is configured to translate a radio frequency band to an intermediate frequency (IF) band. A tunable local oscillator is in signal communication with the mixer. At least one fixed-frequency notch filter is in signal communication with the mixer, with the notch filter configured to reject at least one interference signal in the IF band while passing remaining signals in the IF band. An analog-to-digital converter is in signal communication with the notch filter and is configured to convert the remaining signals in the IF band to digital signals.

Abstract: One embodiment is directed towards an RF receiver for receiving a pulse-position modulated signal transmitted with a 1090 MHz ADS-B transmitter, wherein the pulse-position modulated signal is preceded by a preamble of 4 pulses that conform to an ADS-B protocol. The receiver can filter a digital sample stream with a filter matched to pulses in an earlier half of an expected preamble sequence to produce a first matched filter output sample stream. The receiver can also filter the digital sample stream with a filter matched to a pulses in a latter half of the expected preamble sequence to produce a second matched filter output sample stream. The receiver can determine that a sequence of pulses match the expected preamble sequence based on when the first matched filter output sample stream and the second matched filter output sample stream are above a minimum trigger level at the same time.

Abstract: A wideband multi-channel receiver comprises an antenna configured to receive a radio frequency band comprising an aviation VHF communication band, an aviation VHF navigation band, an aviation L-band, or combinations thereof. A band-pass filter is in signal communication with the antenna, and a low-noise amplifier is in signal communication with the band-pass filter. A mixer is in signal communication with the low-noise amplifier and is configured to translate a radio frequency band to an intermediate frequency (IF) band. A tunable local oscillator is in signal communication with the mixer. At least one fixed-frequency notch filter is in signal communication with the mixer, with the notch filter configured to reject at least one interference signal in the IF band while passing remaining signals in the IF band. An analog-to-digital converter is in signal communication with the notch filter and is configured to convert the remaining signals in the IF band to digital signals.

Abstract: A radio signal processing system includes a first antenna; a second antenna; a first receiver communicatively coupled to the first antenna; a second receiver communicatively coupled to the second antenna; a first processing unit communicatively coupled to the first receiver and configured to receive a first signal from at least one of the first antenna and the second antenna when the system is operating in a first mode; a second processing unit communicatively coupled to the second receiver and configured to receive a second signal from the second antenna when the system is operating in a first mode; and wherein the first processing unit is further configured to receive a third signal from both the first antenna and the second antenna when the system is operating in a second mode.

Abstract: Systems and methods for the selection of antennas in aircraft navigation systems are provided. In one embodiment, a navigation receiver system for an aircraft comprises: a first aircraft antenna that receives transmitter signals from fixed-location ground transmitters and a second aircraft antenna that receives transmitter signals from the fixed-location ground transmitters, wherein the first aircraft antenna has a first gain pattern that is different from a second gain pattern of the second aircraft antenna; a switch coupled to a first receiver and the first and second aircraft antenna; and a switch controller coupled to the switch. The switch controller operates the switch to electrically couple the first receiver to either the first or second aircraft antenna based on a determination of whether the first gain pattern or the second gain pattern provides higher gain in a direction of a first fixed-location ground transmitter of the fixed-location ground transmitters.

Abstract: One embodiment is directed to an aircraft position report system. The system comprises a satellite, an aircraft position reporting receiver mounted on the satellite, an antenna element mounted on the satellite, and an antenna interface mounted on the satellite. The aircraft position reporting receiver receives aircraft position reports through the antenna element by associating a spot beam with a narrow coverage area. The aircraft position reports are derived from a signal produced by the antenna element. The antenna interface changes the narrow coverage area associated with the spot beam to receive aircraft position reports from a wide coverage region within a reporting period. In one exemplary embodiment, the antenna interface mechanically steers the spot beam for each receiver to one of the narrow coverage areas. In another exemplary embodiment, the antenna interface electronically steers the spot beam for each receiver to one of the narrow coverage areas.

Abstract: Systems and methods for receiving ADS-B messages in environments where multipath propagation corrupts the messages or blocks the reception of the messages. An exemplary system combines RF signal processing and digital signal processing techniques to make it possible to receive ADS-B messages in the presence of multipath reflections from nearby structures and/or farther out structures. The system uses an array of horizontally spaced antennas. The RF signals from the antennas are combined by the receiver so as to form a set of beams with different azimuth antenna patterns to increase the probability that the multipath does not combine destructively with the line-of-sight path in at least one of the beams. This effectively removes multipath reflections where the delay of the multipath relative to the line-of-sight path is less than 100-200 nanoseconds. The system is also configured to remove multipath reflections with greater delays relative to the line-of-sight path.

Abstract: A reconfigurable wireless modem adapter is provided. The reconfigurable wireless modem adapter includes a control board and a radio frequency switch. The control board includes at least two user-data interfaces for respective at least two modems, the modems including at least one diversity/multiple-input-multiple-output (MIMO) modem. The control board is configured to communicatively couple to at least one onboard system in a vehicle and to activate one of the at least one diversity/MIMO modem interfaced to one of the at least two user-data interfaces. The radio frequency switch is communicatively coupled to the control board via a modem-select interface and the selected one of the at least one diversity/MIMO modem. The radio frequency switch communicatively couples one of at least one diversity/MIMO antenna on the vehicle to the selected one of the at least one diversity/MIMO modem based on a control signal.

Abstract: A method includes selecting a first communications network from a plurality of communications networks based on one or more aircraft state inputs. The one or more aircraft state inputs include at least one of a flight phase, a flight event, an aircraft position, an aircraft trajectory, an aircraft state, and an aircraft distance from a ground station. The method further includes transmitting data over the first communication network. The method further includes selecting a second communications network from the plurality of communications networks based on a change in the one or more aircraft state inputs.

Abstract: A wideband multi-channel receiver comprises an antenna configured to receive a radio frequency band comprising an aviation VHF communication band, an aviation VHF navigation band, an aviation L-band, or combinations thereof. A band-pass filter is in signal communication with the antenna, and a low-noise amplifier is in signal communication with the band-pass filter. A mixer is in signal communication with the low-noise amplifier and is configured to translate a radio frequency band to an intermediate frequency (IF) band. A tunable local oscillator is in signal communication with the mixer. At least one fixed-frequency notch filter is in signal communication with the mixer, with the notch filter configured to reject at least one interference signal in the IF band while passing remaining signals in the IF band. An analog-to-digital converter is in signal communication with the notch filter and is configured to convert the remaining signals in the IF band to digital signals.

Abstract: A reconfigurable wireless modem adapter is provided. The reconfigurable wireless modem adapter includes a control board and a radio frequency switch. The control board includes at least two user-data interfaces for respective at least two modems, the modems including at least one diversity/multiple-input-multiple-output (MIMO) modem. The control board is configured to communicatively couple to at least one onboard system in a vehicle and to activate one of the at least one diversity/MIMO modem interfaced to one of the at least two user-data interfaces. The radio frequency switch is communicatively coupled to the control board via a modem-select interface and the selected one of the at least one diversity/MIMO modem. The radio frequency switch communicatively couples one of at least one diversity/MIMO antenna on the vehicle to the selected one of the at least one diversity/MIMO modem based on a control signal.

Abstract: A reconfigurable radio communications system is disclosed. The system comprises a digital data bus, a control bus, and first and second reconfigurable radio communication units responsive to the digital data bus and the control bus. Each of the first and second reconfigurable radio communication units further include a first and a second multifunction radio transceiver, with the first reconfigurable radio communication unit responsive to at least a first antenna, and the second reconfigurable radio communication unit responsive to at least a second antenna. Each of the first and the second multifunction radio transceivers of the first and the second reconfigurable radio communication units are operable to simultaneously transmit and receive data on at least two separate channels from different frequency bands.

Abstract: A reconfigurable radio communication subsystem is provided comprising a first radio communication unit communicatively coupled to a first antenna and a second antenna, and a second radio communication unit communicatively coupled to a third antenna and the first or second antenna. The first, second, and third antennas are operable in a first frequency band. The subsystem includes a first antenna subsystem coupled to the first radio communication unit and a fourth antenna operable in a second frequency band, and a second antenna subsystem coupled to the second radio communication unit and the fourth antenna. The first and second radio communication units include reconfigurable voice/data functions operating in the first frequency band, voice/data functions operating in the second frequency band, and a radio communications system management function. Cross-connecting buses couple the first radio communication unit and the second radio communication unit.

Abstract: An apparatus for transmitting and receiving multiple radio frequencies simultaneously over a single antenna is provided. The apparatus comprises a transmitter signal combining apparatus configured to communicatively couple with a plurality of transmitters, wherein the transmitter signal combining apparatus is configured to output a transmission signal based on any signals received from the plurality of transmitters. The apparatus also includes at least one transmit/receive signal duplexer coupled to the transmitter signal combining apparatus and configured to provide the transmission signal to an antenna, wherein the antenna receives an incoming radio frequency (RF) signal. Additionally, the apparatus includes a signal separation apparatus coupled to the at least one transmit/receive signal duplexer and configured to receive the incoming RF signal and provide the incoming RF signal to at least one receiver.

Abstract: A method includes selecting a first communications network from a plurality of communications networks based on one or more aircraft state inputs. The one or more aircraft state inputs include at least one of a flight phase, a flight event, an aircraft position, an aircraft trajectory, an aircraft state, and an aircraft distance from a ground station. The method further includes transmitting data over the first communication network. The method further includes selecting a second communications network from the plurality of communications networks based on a change in the one or more aircraft state inputs.

Abstract: A method for routing aircraft data link messages over a plurality of communications networks is disclosed. The method assigns at least one data link message routing service for an aircraft having a first message processing application based on prescribed criteria, the prescribed criteria comprising preferred networks of the plurality of communications networks. As a first preferred communications network becomes available, the method selects a first message route from the assigned routing service and transmits each of the data link messages on the first message route while the first message route satisfies the prescribed criteria. When the prescribed criteria changes over a plurality of flight phases of the aircraft, the method reassigns the at least one data link message route to continue data link message transmissions to and from the aircraft based on the latest prescribed criteria.

Abstract: A reconfigurable radio communication subsystem is provided comprising a first radio communication unit communicatively coupled to a first antenna and a second antenna, and a second radio communication unit communicatively coupled to a third antenna and the first or second antenna. The first, second, and third antennas are operable in a first frequency band. The subsystem includes a first antenna subsystem coupled to the first radio communication unit and a fourth antenna operable in a second frequency band, and a second antenna subsystem coupled to the second radio communication unit and the fourth antenna. The first and second radio communication units include reconfigurable voice/data functions operating in the first frequency band, voice/data functions operating in the second frequency band, and a radio communications system management function. Cross-connecting buses couple the first radio communication unit and the second radio communication unit.