A method for positioning an underwater glider based on a virtual TDOA of a single beacon is provided. In the method, a positioning beacon periodically sends positioning messages, where the positioning message includes longitude, latitude and depth information of the positioning beacon; the underwater glider receives the positioning messages and records TOAs at which the positioning messages arrive at an acoustic positioning signal receiving module; and the underwater glider parses the positioning messages and stores positioning message data, creates virtual beacons based on beacon information and attitude information of the underwater glider, corrects the TOAs, and calculates a position of the underwater glider according to a TDOA algorithm. According to the method, the underwater glider passively listens to and receives the positioning messages without sending a positioning request to the positioning beacon, making the entire positioning process energy-saving with a certain degree of concealment.

A method for positioning an underwater glider based on a virtual TDOA of a single beacon is provided. In the method, a positioning beacon periodically sends positioning messages, where the positioning message includes longitude, latitude and depth information of the positioning beacon; the underwater glider receives the positioning messages and records TOAs at which the positioning messages arrive at an acoustic positioning signal receiving module; and the underwater glider parses the positioning messages and stores positioning message data, creates virtual beacons based on beacon information and attitude information of the underwater glider, corrects the TOAs, and calculates a position of the underwater glider according to a TDOA algorithm. According to the method, the underwater glider passively listens to and receives the positioning messages without sending a positioning request to the positioning beacon, making the entire positioning process energy-saving with a certain degree of concealment.

A practically implementable robust direction-of-arrival (DoA) estimation approach that is resistant to localization errors due to mobility, multipath reflections, impulsive noise, and multiple-access interference. As part of the disclosed invention the inventors consider infrastructure-less 3D localization of autonomous underwater vehicles (AUVs) with no GPS assistance and no availability of global clock synchronization. The proposed method can be extended to challenging communication environments and applied for the localization of assets/objects in space, underground, intrabody, underwater and other complex, challenging, congested and sometimes contested environments. Each AUV leverages known-location beacon signals to self-localize and can simultaneously report its sensor data and measurement location. The approach uses two known location beacon nodes, where the beacons are single-hydrophone acoustic nodes that are deployed at known locations and transmit time-domain coded signals in a spread-spectrum fashion.

An Automatic Identification System (AIS) for tracking a plurality of maritime vessels may include a ground AIS server and a constellation of Low-Earth Orbit (LEO) satellites in communication with the ground AIS server. Each LEO satellite may include an AIS payload configured to receive AIS messages from the plurality of maritime vessels and determine therefrom reported vessel position data, determine an actual frequency of arrival (FOA) for each of the AIS messages, determine an expected FOA for each of the AIS messages based upon the reported vessel position data for each AIS message, determine a potential spoofing maritime vessel based upon a difference between a corresponding expected FOA and actual FOA for a given AIS message, and send a potential spoof alert to the ground AIS server.

A processor enabled method in a mobile device includes configuring a WiFi radio controller of the mobile device with a WiFi service set identifier of a search detector and configuring a Bluetooth connection configuration of a search detector. The method also includes responsive to a rescue trigger, enabling the device to exit a low power mode while awaiting a connection attempt from a Bluetooth radio via the configured Bluetooth connection configuration. The method also includes upon receiving the connection attempt, powering up the WiFi radio and attempting to connect to the configured WiFi service set identifier.

Embodiments of the present invention provide a navigation system which, on the one hand, is arranged on sides of the underwater vehicle/AUV and, on the other hand, includes a surface transmitter as a counterpart. The two units communicate with each other such that the surface transmitter emits its signal directed to the position of the underwater vehicle and/or that the surface transmitter follows the underwater vehicle to improve the position determination capability.

A system and a method are disclosed for enabling seamlessly tracking a location of a water vessel by supplementing satellite data with mobile data location based on proximity of a water vessel to shore. The system receives a Global Positioning System (GPS) location of the water vessel, the GPS location of the water vessel based on using the satellite data of the water vessel. The system determines that the GPS location is within a threshold distance of a boundary. Responsive to determining that the GPS location is within the threshold distance of the boundary, the system initiates monitoring for a mobile signal emanating from a trajectory path of the water vessel. The system detects, during the monitoring, the mobile signal, the tracking the location of the water vessel based on mobile data of the mobile signal. The system provides the tracked location to a monitoring device.

This disclosure provides a data-driven approach to departure detection. In particular, the disclosed approach uses location data, such as GPS, which is readily available for many vessels globally and historically through the automatic identification system (AIS). The approach clusters this data and then constructs a convex hull around these clusters for each port to define a port area. A vessel is then determined as departed when it leaves that port area. Clustering is computationally efficient as a number of optimised algorithms exist, which means even a very large dataset like historical locations of thousands of vessels can be processed relatively quickly. Further, the departure detection enables accurate estimation of arrival times. Further, actions can be triggered by the departure determination, such as automatic control of cranes, trucks, trains and other port equipment.

A practically implementable robust direction-of-arrival (DoA) estimation approach that is resistant to localization errors due to mobility, multipath reflections, impulsive noise, and multiple-access interference. As part of the disclosed invention the inventors consider infrastructure-less 3D localization of autonomous underwater vehicles (AUVs) with no GPS assistance and no availability of global clock synchronization. The proposed method can be extended to challenging communication environments and applied for the localization of assets/objects in space, underground, intrabody, underwater and other complex, challenging, congested and sometimes contested environments. Each AUV leverages known-location beacon signals to self-localize and can simultaneously report its sensor data and measurement location. The approach uses two known location beacon nodes, where the beacons are single-hydrophone acoustic nodes that are deployed at known locations and transmit time-domain coded signals in a spread-spectrum fashion.

An underwater positioning system comprises a plurality of underwater beacons. A beacon, in response to a signal sent by an underwater vehicle, responds with a signal comprising one or more characteristics to identify the beacon. Components of an access algorithm are provided to the underwater vehicle. The access algorithm determines a location of the beacon based on the beacon's identity. A position of the vehicle is determined based at least in part on the location of the beacon.