An antenna receiver has antenna elements that are arranged in an array and spaced apart from each other at a distance greater than one-half wavelength of the highest operating frequency of a signal that is to be detected by the antenna receiver. The antenna receiver has geolocation logic that uses the inter-element phase difference measurements to obtain a location of the signal source. The change in the inter-element phase differences enables the elements to be spaced apart at great distances, which is beneficial for the physical construction of the platform, as the elements may be easily placed at convenient locations for conformal aerodynamic properties.

First information is obtained from a sensing device at a first time. The first information corresponds to a radio signal received at the device from a candidate location. The device is at a first location at the first time. Second information is obtained from the device at a second time. The second information corresponds to a radio signal received at the device from the candidate location. The device is at a second location at the second time. A system determines that a pattern is in each of the first and second information and determines relationships between the candidate location and the device at each first and second location. The system obtains inverses of the relationships and determines estimates of the received radio signals based on the information and inverses. The system measures or estimates energy emitted from the candidate location based on the estimates.

A location search method using a mobile device in multiple locations. In one embodiment of the method, the mobile device receives a first radio frequency (RF) signal transmitted by a first device while the mobile device is at a first geographical location. The mobile device receives a second RF signal transmitted by the first device while the mobile device is at a second geographical location, which is different from the first mobile device geographical location. The mobile device determines a geographical location of the first device based on the first RF signal, the second RF signal, the first mobile device geographical location, and the second mobile device geographical location.

A method of determining the location of the first object (10) may include receiving signals at a second object (20) from a plurality of measurement points (11) on the first object (10), estimating locations of the plurality of measurement points (11) on the first object (10), determining an estimate of a location of the first object (10), determining a first measurement of an orientation of the first object (10) based on the estimating of the locations of the plurality of measurement points (11) on the first object (10), and determining a second measurement of the orientation of the first object (10) based on measurements by an orientation sensor (12) on the first object (10). The method may include estimating an error of the estimate of the location of the first object (10) based on a difference between the first and second orientation measurements and adjusting a movement of the second object (20) based on the estimated error.

A mobile robot is configured for operation in a commercial or industrial setting, such as an office building or retail store. The robot can patrol one or more routes within a building, and can detect violations of security policies by objects, building infrastructure and security systems, or individuals. In response to the detected violations, the robot can perform one or more security operations. The robot can include a removable fabric panel, enabling sensors within the robot body to capture signals that propagate through the fabric. In addition, the robot can scan RFID tags of objects within an area, for instance coupled to store inventory. Likewise, the robot can generate or update one or more semantic maps for use by the robot in navigating an area and for measuring compliance with security policies.

Systems and methods for determining a physical location of a first Radio Frequency Identification (RFID) tag. The methods involve: analyzing timestamped tag read information acquired during multiple tag reads to determine a first physical location for the first RFID tag read by the mobile reader while moving through a facility; identifying second RFID tags from a plurality of RFID tags read by the mobile reader that are located in proximity to the first RFID tag and that are coupled to objects similar to an object to which the first RFID tag is coupled; selecting an RFID tag from the second RFID tags that has a first location confidence value associated therewith which is greater than second location confidence values associated with other RFID tags of the second RFID tags; and modifying the first physical location based on a second physical location at the time of reads, location of the RFID tag selected from the second RFID tags.

Disclosed is a technique that can provide one or more countermeasures against spoofers. A beamformer can control an antenna pattern of a CRPA to generate a survey beam. The survey beam is swept across space to determine a characteristic signature based on carrier-to-noise ratios (C/No) for particular space vehicle signals. Matching C/No signatures can be used to identify the existence of spoofers and invoke a countermeasure, such as nulling.

An illustrative embodiment disclosed herein is a method including estimating, by an endpoint, a first rate of change of a Doppler frequency offset during a downlink reception from a satellite associated with the Doppler frequency offset and applying, by the endpoint, a second rate of change of the Doppler frequency offset to an uplink transmission to the satellite. The second rate of change of the Doppler frequency offset compensates the first rate of change of the Doppler frequency offset.

An illustrative embodiment disclosed herein is a satellite including a transceiver, a first antenna, a second antenna, and a switch to enable only the first antenna by electrically coupling the first antenna to the transceiver responsive to a satellite constellation having less than a threshold number of satellites and enable only the second antenna by electrically coupling the second antenna to the transceiver responsive to the satellite constellation having greater than the threshold number of satellites.

An illustrative embodiment disclosed herein is a method including determining, by a location server, a satellite constellation, a location of a target endpoint, and a next available time of the target endpoint. The method further includes determining, by the location server, a plurality of candidate satellites based on the satellite constellation, the location of the target endpoint, and the next available time of the target endpoint. The method further includes instructing, by the location server, a ground station to broadcast a downlink signal to the plurality of candidate satellites.