The present disclosure relates to a location determination system that includes acoustic transmitting devices (104), location tags (112), and a wireless mesh network (106), where the wireless mesh network uses battery-powered devices. A location tag receives acoustic signals (e.g., ultrasound signals) from an acoustic transmitting device. Clocks from members of the wireless mesh network are synchronized by observation of clock pairings, each clock pair formed by respective clocks in a transmitting device that transmits a message and a receiving device that receives the message. By analyzing the observed clock pairings, a best fit between the clock pairings may be determined. After selecting a reference clock, an acoustic transmission schedule may be propagated to the respective acoustic transmitting device.

Deployable navigation beacons can be deployed from a vehicle, such as an unmanned aerial vehicle (UAV), in an event of a loss of position or orientation of the vehicle. After deployment of the navigation beacons, the vehicle may detect locations of the navigation beacon, which may define a surface that may include surface features. The vehicle may then perform control operations based on the resolved locations. For example, UAV may maneuver to land proximate to the navigation beacons after resolving locations of the navigation beacons as a continuous surface. The navigation beacons may output a visual signal (e.g., a light), a auditory signal (e.g., a sound), and/or a radio signal. In some embodiments, each navigation beacon may include a different or unique signal.

An ultrasonic transmitter apparatus is configured to transmit an ultrasonic signal that communicates a binary identifier. The apparatus includes an ultrasound transmission system and is configured to transmit an ultrasonic signal that communicates the binary identifier according to an encoding in which each bit position in the binary identifier is associated with a respective pair of frequencies and with respective first and second time positions in the ultrasonic signal. The value of the bit position in the binary identifier determines which frequency of the pair of frequencies is transmitted at the first respective time position in the ultrasonic signal, with the other frequency of the pair of frequencies being transmitted at the second respective time position in the ultrasonic signal.

An apparatus and method for measuring a swimmer's speed and conveying the speed to the swimmer in real time includes a plurality of ultrasonic beacons each having a transducer configured to emit ultrasonic signals in a pool or other body of water within which the swimmer is swimming. A wearable, waterproof, ultrasonic receiver worn by the swimmer, receives the ultrasonic signals and generates corresponding signal data. The receiver's microcontroller captures and uses the signal data to calculate the swimmer's position and speed in real time, and conveys this information to a wearable, waterproof, user interface device worn by the swimmer, the user interface device including a near-eye display disposed on the swimmer's goggles.

The present disclosure relates to a location determination system that includes acoustic transmitting devices, location tags, and a wireless mesh network, where the wireless mesh network uses battery-powered devices. A location tag receives acoustic signals (e.g., ultrasound signals) from an acoustic transmitting device. Clocks from members of the wireless mesh network are synchronized by observation of clock pairings, each clock pair formed by respective clocks in a transmitting device that transmits a message and a receiving device that receives the message. By analyzing the observed clock pairings, a best fit between the clock pairings may be determined. After selecting a reference clock, an acoustic transmission schedule may be propagated to the respective acoustic transmitting device.

A water surface and underwater dual-purpose automatic positioning and tracking system and method, which belongs to the field of marine environment observation technologies. The positioning and tracking system includes: a rope winding and unwinding structure, arranged on a main hull structure; where the rope winding and unwinding structure includes a rope roller and a winding and unwinding rope wound around the rope roller; an auxiliary positioning remote control ship, located outside a main body of the main hull structure, where the auxiliary positioning remote control ship is in transmission and fixed connection with the winding and unwinding rope away from the rope roller; communication control units, arranged on the main hull structure and the auxiliary positioning remote control ship; and an automatic positioning tracker unit, arranged on the hull structure, where the automatic positioning tracker unit is in remote communication connection with the communication control units.

An electronic fish finder transducer lifting system includes a mechanical actuating device; a transducer lifting device; an electronic fish finder attachment member, rotatably connected to the transducer lifting device, configured to attach to an electronic fish finder; and a mechanical linkage, connected to the mechanical actuating device and the transducer lifting device, configured to transfer force, applied to the mechanical actuating device, to the transducer lifting device to lift a front portion of the transducer lifting device.

The invention provides a navigation device comprising a docking portion configured to securely adhere to a surface and a unit having at least one of a visual, an audio or tactile indicator. The present invention provides a device which the user attaches to a wall or door or ground surface entered on the way into a building. A number of fixed devices then assist the user to retrace their route out of the building. In addition, the device can be configured to transmit essential information to a user located outside the building. The devices can also be configured to form a novel navigation communication system.

A method and apparatus for locating a target in a venue is described. A backend controller activates transmitters in a venue to send burst signals using a double symmetry configuration formed of a plurality of separate transmitter groups. The backend controller activates the transmitters into a second, different configuration for bursting. The resulting location signal information from each configuration is obtained by the backend controller, which then more accurately determines the location of the target in the venue.

A water surface and underwater dual-purpose automatic positioning and tracking system and method, which belongs to the field of marine environment observation technologies. The positioning and tracking system includes: a rope winding and unwinding structure, arranged on a main hull structure; where the rope winding and unwinding structure includes a rope roller and a winding and unwinding rope wound around the rope roller; an auxiliary positioning remote control ship, located outside a main body of the main hull structure, where the auxiliary positioning remote control ship is in transmission and fixed connection with the winding and unwinding rope away from the rope roller; communication control units, arranged on the main hull structure and the auxiliary positioning remote control ship; and an automatic positioning tracker unit, arranged on the hull structure, where the automatic positioning tracker unit is in remote communication connection with the communication control units.