Abstract: GNSS receivers and methods of determining a current receiver state of a GNSS receiver are provided. The method includes receiving positioning signals from a plurality of satellites; generating a plurality of correlation grids from the received positioning signals, where each correlation grid is associated with a respective one of the plurality of satellites; estimating a probability distribution of the current receiver state from the plurality of correlation grids; and determining a maximum likelihood estimate of the current receiver state from the estimated probability distribution.

Abstract: A method of determining the proximity of a first device to a second device, the method comprising, at the second device: receiving a first packet having a first payload and a first lifetime value, the first lifetime value being such so as to cause a device receiving the first packet to not retransmit the first payload; and generating, in dependence on the first packet, a second packet having a second payload and a second lifetime value, the second payload being indicative of the proximity of the first device to the second device and the second lifetime value being such as to cause a device receiving the second packet to retransmit the second payload.

Abstract: A communication device configured to form a cluster with one or more other communication devices in its vicinity, monitor the presence, in the cluster, of those other communication devices and provide information about the presence, in the cluster, of the other communication devices to another device.

Abstract: A method and apparatus for harvesting information from a plurality of radio frequency (RF) sources. In one example, a collector device receives RF signals from the RF sources to produce the harvesting information. The collector device also determines environmental context information describing a physical environment of the collector device as the RF signals were being received, and a position of the collector device where the RF signals where received. The collector device then associates the environmental context information with the harvesting information and the position, and transmits the harvesting information and position with the associated environmental context information to a server device. The server device may then compute positioning information biased to different environmental contexts. This biased positioning information may then be utilized by other collector devices having similar environmental contexts to better estimate their respective locations.

Abstract: GNSS receivers and methods of determining a current receiver state of a GNSS receiver are provided. The method includes receiving positioning signals from a plurality of satellites; generating a plurality of correlation grids from the received positioning signals, where each correlation grid is associated with a respective one of the plurality of satellites; estimating a probability distribution of the current receiver state from the plurality of correlation grids; and determining a maximum likelihood estimate of the current receiver state from the estimated probability distribution.

Abstract: A method for tracking collector devices in an indoor area associated with imaging devices and RF signal sources covering the area includes generating aspects of a plurality of coarse position tracks of the collector devices based on RF signal measurements obtained by the collector devices from the RF signal sources. Imaging devices capture image frames of the collector devices in the indoor area which are then processed in order to determine aspects of a plurality of fine position tracks of the collector devices. The server and the collector device communicate with each other and match aspects of at least one of the fine position tracks to the aspects of the coarse position track of the communicating collector device in order to determine the precise location of the collector device in the indoor area.

Abstract: A system for location based security which includes a plurality of receivers. Each of the receivers determines limes of arrival of received time varying signals. The system also includes a server in communication with the receivers and a mobile device. The server receives the times of arrival from the receivers, and times of arrival of the time varying signals determined by the mobile device. The server determines a location of the mobile device based on the times of arrival. The server may then authorize the mobile device to perform secure communication over the secure communication network when the location of the mobile device is determined to be in an authorized communication area defined based on the Limes of arrival received from the receivers.

Abstract: GNSS receivers and methods of determining a current receiver state of a GNSS receiver are provided. The method includes receiving positioning signals from a plurality of satellites; generating a plurality of correlation grids from the received positioning signals, where each correlation grid is associated with a respective one of the plurality of satellites; estimating a probability distribution of the current receiver state from the plurality of correlation grids; and determining a maximum likelihood estimate of the current receiver state from the estimated probability distribution.

Abstract: A method for detecting a collector device in an indoor area associated with imaging devices covering the area includes a plurality of collector devices emitting markers to the imaging devices coupled to a server. The imaging devices capture the images of the collector devices including the markers. The images are processed in order to determine the current positions of the collector devices corresponding to the markers. The server and the collector device communicate with each other and match a current position corresponding to the collector device among the plurality of collector devices.

Abstract: Apparatus for calculating the position of a receiver in dependence on the time it takes signalling events to travel from a plurality of satellites to the receiver, obtains an indication of a transit time for a signalling event to travel from each satellite to the receiver, and forms an indication of an expected transit time for a signalling event to travel from the satellite to the receiver. The obtained indication of the transit time and the indication of the expected transit time for each non-reference satellite are compared with the obtained indication of the transit time and the indication of the expected transit time for the reference satellite to form residuals that are representative of a combined error in those indications of expected transit time; and the position of the receiver is calculate without calculating the integer ambiguities in the obtained transit times, in dependence on the residuals.

Abstract: A system for location based security which includes a plurality of receivers. Each of the receivers determines times of arrival of received time varying signals. The system also includes a server in communication with the receivers and a mobile device. The server receives the times of arrival from the receivers, and times of arrival of the time varying signals determined by the mobile device. The server determines a location of the mobile device based on the times of arrival. The server may then authorize the mobile device to perform secure communication over the secure communication network when the location of the mobile device is determined to be in an authorized communication area defined based on the times of arrival received from the receivers.

Abstract: A system and method for determining locations of a plurality of radio frequency (RF) signal sources. The method includes receiving RF signals from the RF signal sources, and determining locations of the RF signal sources based on the received RF signals. The method also includes determining an anchor having an absolute location identified by map data, and then adjusting the determined locations of the RF signal sources based on the anchor.

Abstract: Apparatus for calculating the location of a receiver by means of a location algorithm that generates a receiver location in dependence on signalling events received by that receiver from a set of satellites, the apparatus being arranged to select, from a constellation of satellites visible to the receiver, the set of satellites to use in the location algorithm in dependence on an effect that it is estimated using that set of satellites will have on the capability of the location algorithm to generate an accurate location for the receiver.

Abstract: A system and method which identifies locations associated with radio-frequency (RF) signal sources in an area, includes receiving multiple measurement sets from a plurality of collector devices. The collector devices obtain contemporaneous information on characteristics of the signal sources and absolute and/or relative location information of the collectors. These measurement sets are processed to discover positioning data for the RF signal sources that may be used to determine locations of devices in the area that are configured to receive or monitor the RF signals.

Abstract: A method of determining the proximity of a first device to a second device, the method comprising, at the second device: receiving a first packet having a first payload and a first lifetime value, the first lifetime value being such so as to cause a device receiving the first packet to not retransmit the first payload; and generating, in dependence on the first packet, a second packet having a second payload and a second lifetime value, the second payload being indicative of the proximity of the first device to the second device and the second lifetime value being such as to cause a device receiving the second packet to retransmit the second payload.

Abstract: A communication device configured to form a cluster with one or more other communication devices in its vicinity, monitor the presence, in the cluster, of those other communication devices and provide information about the presence, in the cluster, of the other communication devices to another device.

Abstract: Apparatus for calculating the location of a receiver in a satellite navigation system, the apparatus being arranged to calculate a location of the receiver by means of an algorithm that utilizes an estimate of receiver location and/or an estimate of absolute time, the apparatus being arranged to perform the calculation in such a way as to extend a convergence zone within which the algorithm is capable of generating the correct location for the receiver despite an error in the estimate(s).

Abstract: An apparatus for determining a location of a receiver by using signals received by the receiver from a number of satellites, the apparatus being configured to, when the receiver has been unable to decode a time-of-transmission from the satellite signals, determine a location for the receiver by use of an algorithm that takes an estimate of the location of the receiver as an input, and, when an estimate of the location of the receiver is unavailable, determine an approximate location of the receiver in dependence on the satellite signals and input that approximate location into the algorithm as the estimate of the location of the receiver.

Abstract: A system and method for determining locations of a plurality of radio frequency (RF) signal sources. The method includes receiving RF signals from the RF signal sources, and determining locations of the RF signal sources based on the received RF signals. The method also includes determining an anchor having an absolute location identified by map data, and then adjusting the determined locations of the RF signal sources based on the anchor.

Abstract: A method for detecting a collector device in an indoor area associated with imaging devices covering the area includes a plurality of collector devices emitting markers to the imaging devices coupled to a server. The imaging devices capture the images of the collector devices including the markers. The images are processed in order to determine the current positions of the collector devices corresponding to the markers. The server and the collector device communicate with each other and match a current position corresponding to the collector device among the plurality of collector devices.