There is provided a navigation system, comprising: a buoy on a water surface movably anchored to a bottom; a plurality of at least three transmitters fixed to the bottom or at different positions in the water for transmitting signals to specify the positions; a receiver, being disposed with the buoy, configured to receive signals transmitted by the plurality of transmitters; a signal processor, being disposed with the buoy, configured to specify the position of the buoy, based on the signals received by the receiver, and generate a navigation signal indicating the position of the buoy, and a radio, being disposed with the buoy, configured to transmit the navigation signal generated in the signal processor wirelessly, the navigation signal being receivable by a radio in a mobile body.

Described is an improved active-beacon/passive-listener time difference of arrival navigation system that relies on the multiple beacons to transmit uncoded acoustic pulses of a same frequency that propagate in the system at a same time for high-speed device tracking. Listening devices may receive multiple encoded radio frequency pulses (RF) prior to a single acoustic pulse, and then resolve which RF pulse corresponds to the acoustic pulse using triangulation techniques.

A method comprising: receiving a reference time delay between a first reference signal emitted by a first speaker and a second reference signal emitted by a second speaker, each recorded by a microphone having a target position; using the microphone positioned at an actual position, recording a first sound signal emitted by the first speaker and a second sound signal emitted by the second speaker; determining an actual time delay between the first and second sound signals; comparing the actual time delay to the reference time delay; determining a match or a mismatch between the actual position and the target position for the given microphone; and outputting an indication of the match/mismatch.

An AR/VR input device include a processor(s), an internal measurement unit (IMU), and a plurality of sensors configured to detect emissions received from a plurality of remote emitters. The processor(s) can be configured to: determine a time-of-flight (TOF) of the detected emissions, determine a first estimate of a position and orientation of the input device based on the TOF of a subset of the detected emissions and the particular locations of each of the plurality of sensors on the input device that are detecting the detected emissions, determine a second estimate of the position and orientation of the input device based on the measured acceleration and velocity from the IMU, and continuously update a calculated position and orientation of the input device within the AR/VR environment in real-time based on a Beyesian estimation (e.g., Extended Kalman filter) that utilizes the first estimate and second estimate.

A leaky-wave antenna for fluid environments includes a waveguide cavity defined by a waveguide wall. The waveguide cavity is filled with a waveguide fluid. The waveguide walls are made of either an anisotropic material that utilize one of orthotropic stiffness of the anisotropic material to control mode conversion, a band gap material to approximate an acoustically rigid boundary, and a combination of the two materials.

A leaky-wave antenna for fluid environments includes a waveguide cavity defined by a waveguide wall. The waveguide cavity is filled with a waveguide fluid. The waveguide walls are made of either an anisotropic material that utilize one of orthotropic stiffness of the anisotropic material to control mode conversion, a band gap material to approximate an acoustically rigid boundary, and a combination of the two materials.

A method for finding door location in an automated way based on observations of people that are equipped with a device whose position is determined acoustically. By observing positioning transitions across internal structures such as walls, the location of doors can be automatically identified.

A method for finding door location in an automated way based on observations of people that are equipped with a device whose position is determined acoustically. By observing positioning transitions across internal structures such as walls, the location of doors can be automatically identified.

In a positioning system, a plurality of transmitter units (2, 3, 4, 5) transmit respective transmitter-specific identification signals at intervals, which are received at a mobile receiver unit (7). A processing system (7; 9) identifies the transmitter unit that transmitted each received identification signal, and, for each signal, determines range data from time of arrival data and determines distance data from Doppler shift information. The range data and distance data are compared to determine range error data. A position estimate for the mobile receiver unit (7) is determined by solving an optimisation problem using range estimates determined for the plurality of transmitter units, weighted in dependence on the range error data.

In a positioning system, a plurality of transmitter units (2, 3, 4, 5) transmit respective transmitter-specific identification signals at intervals, which are received at a mobile receiver unit (7). A processing system (7; 9) identifies the transmitter unit that transmitted each received identification signal, and, for each signal, determines range data from time of arrival data and determines distance data from Doppler shift information. The range data and distance data are compared to determine range error data. A position estimate for the mobile receiver unit (7) is determined by solving an optimisation problem using range estimates determined for the plurality of transmitter units, weighted in dependence on the range error data.