Aireon LLC

Exelis Inc.

Michael A Garcia

John M Dolan

Robert P Mueller

Boris Veytsman

John W Lambert

Jay Minnix

James Stafford

Antonio Scarciglia

Andrew Hoag

Eric Innis

John Dolan

Robert Mueller

In one implementation, a method includes receiving versions of a message from a first satellite-based receiver and a second satellite-based receiver that both received a radio frequency ('RF') transmission of the message, the message comprising a self-reported position of a transmitter of the message. The method also includes determining a time difference between a first arrival time of the RF transmission of the message at the first satellite-based receiver and a second arrival time of the RF transmission of the message at the second satellite-based receiver. The method further includes determining a measure of the likelihood that the self-reported position of the transmitter is valid based on the time difference between the first and second arrival times. The method still further includes transmitting an indication of the measure of the likelihood that the self-reported position is valid.

Position validation

In one implementation, first and second messages are received that include encoded position information for a transmitter. It is determined that both were received within some time of a previous message and that the second message was received within some time of the first message. A first location of the transmitter is determined based on the encoded position in the first message and the previously determined location. A second location of the transmitter is determined based on the encoded position in the second message and the previously determined location. It also is determined that the first and second locations are within a threshold distance. An updated second location of the transmitter is determined based on the encoded position information in the second message and the first location. A determination is made that the second location and the updated second location are within a threshold distance.

Decoding position information

In one implementation, a method includes receiving a number of instances of a message that includes a self-reported position of a transmitter of the message from a corresponding number of satellite-based receivers that each received an RF transmission of an instance of the message. The method also includes determining the number of satellite-based receivers that received an instance of the message and selecting a validation technique based on the number of satellite-based receivers that received an instance of the message. If the number of satellite-based receivers that received an instance of the message is one, a propagation-based validation technique is selected. The method further includes determining a measure of the likelihood that the self-reported position of the transmitter is valid using the selected validation technique, and transmitting an indication of the measure of the likelihood that the self-reported position is valid.

Kinematics-augmented position validation

In one implementation, a method includes receiving simulated RF transmission data indicative of anticipated RF transmissions from a plurality of transmitters, wherein individual anticipated RF transmissions carry corresponding messages, and simulated position data indicative of an anticipated position of each of the plurality of transmitters. The method further includes modeling characteristics of a communications channel expected between a satellite-based receiver and at least some of the transmitters, wherein the satellite-based receiver is configured to define one or more beams for receiving anticipated RF transmissions. The method additionally includes determining a likelihood of the receiver successfully extracting one or more components of a message from one of the anticipated RF transmissions based on at least the simulated RF transmission data, the simulated position data, and the modeled characteristics of the communications channel.

Simulating reception of transmissions

In one implementation, a pair of messages are received from one or more space-based receivers that each received the pair of messages. The pair of messages comprise encoded position information of a transmitter, and a plurality of candidate locations for the transmitter is determined therefrom. A location of the transmitter is determined by eliminating candidate locations until only one remains. In particular, each candidate location that is not within a coverage area of each of the space-based receivers is eliminated, and each candidate location that is not within a predetermined distance of at least one previous candidate location is eliminated. In addition, it is determined that the remaining candidate location is within the coverage area of each of the space-based receivers as well as within the predetermined distance of at least one previous candidate location. Upon determining the location of the transmitter, it is transmitted to a subscriber system.

Decoding position information in space-based systems

In one implementation, satellite coverage provisioning for a service area may be performed by updating power consumption states for satellites in a constellation of satellites and determining whether each satellite of the constellation is required to be in the minimal power consumption mode based on its updated power consumption state. For satellites that are not required to be in the minimal power consumption mode, a power consumption score may be calculated and these satellites may be sorted according to their respective power consumption scores. Based on the sorted order, it may be determined whether at least some of these satellites can be put into a reduced power consumption mode based on their respective power consumption scores and coverage of the service area. Then it may be determined if each of the satellites that are in the reduced power consumption mode can be put into the minimal power consumption mode.

Provisioning satellite coverage

In one implementation, a method for scheduling beams of an antenna on a satellite during a defined time period includes calculating a beam score for each beam based on the expected gain of the beam and determining that the number of beams having non-zero beam scores during the defined time period is less than a threshold value. In addition, the method also includes accessing a set of beam weights for each of multiple different candidate beam patterns, and, for each set of weights, multiplying individual beam weights by corresponding beam scores, and generating a candidate beam pattern score by calculating a sum of the products of the beam weights and corresponding beam scores. The method further includes comparing the candidate beam pattern scores, selecting a particular one of the candidate beam patterns, and scheduling the selected beam pattern for the defined time period.

Scheduling beams of a satelite antenna

A technique for reducing altitude error involves determining a corrected altitude for an aircraft using forecast atmospheric pressure data available, for example, from a weather forecasting service. The forecast atmospheric pressure data includes, for a number of points in time and for a number of geographic locations, a set of pressure levels and corresponding altitude values. Altitude correction data is periodically calculated from the forecast atmospheric pressure data for each of a number of geographic grid points. Upon receiving aircraft position information and an aircraft altitude measurement for an aircraft, one or more of the geographic grid points corresponding to the aircraft position are identified, and a corrected altitude of the aircraft is determined based on the altitude correction data of the one or more geographic grid points.

Reduction of altitude error using forecasted atmospheric pressure data

A computer simulates flight routes for simulated airborne transmitters across a spatial region divided into unit area tiles and over time based on actual aircraft flight plan data. The computer determines transmitter counts per tile per time interval based on the flight routes and assigns transmit parameters, including transmit message rates, to the transmitters. The computer determines transmit message rates per tile based on the transmitter counts and the transmit parameters. The computer generates, for a simulated receiver, an antenna pattern covering at least some of the tiles, and converts the transmit message rates of the covered tiles to a total effective receive message rate of interfering messages at the receiver. The computer determines a probability of successful detection of a desired message among the interfering messages at the receiver based on the effective receive message rate.

Co-channel interference model and use thereof to evaluate performance of a receiver

A technique for determining the position of a mobile device includes receiving messages from respective mobile reference devices. Each of the messages is broadcast beginning at one of several predetermined message start opportunity (MSO) times that have known timings relative to a reference time. Each of the messages contains a MSO value identifying the MSO time at which transmission of the message started. The MSO value is used to determine the time of transmission of each of the messages received at the mobile device, and the position of the mobile device is determined via multi-lateration. According to another approach, the mobile device receives a set of ADS-B messages from a respective set of mobile reference devices. The time of transmission of each of the ADS-B messages is supplied in the ADS-B message itself or in a subsequent message and used to determine the position of the mobile device.

Determination of state vector, timing, and navigation quality metrics from reception of ADS-B transmissions

A technique for determining the position of a mobile device includes receiving at the mobile device a set of time-slotted messages from a respective set of reference devices. Each of the time-slotted messages contains a slot ID indicating the assigned time slot in which it was broadcast. The slot ID is used to determine the time of transmission of each of the time-slotted messages received at the mobile device, and the position of the mobile device is determined via multi-lateration based on the time of flight of the time-slotted messages and known positions of the reference devices. According to another approach, the mobile device receives a set of ADS-B messages from a respective set of SBS ground stations. The time of transmission of each of the ADS-B messages is supplied in the ADS-B message itself or in a subsequent message and used to determined the position of the mobile device.

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Ashburn, VA, United States of America

Michael A Garcia