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 underwater communications network may include spaced apart nodes on a bottom of a body of water. The underwater communications network may also include fiber optic cabling connecting the spaced apart nodes. Each node may include a frame, a node short-range navigation device carried by the frame, and an unmanned underwater vehicle (UUV) carried by the frame after delivering a fiber optic cable along a navigation path from an adjacent node. The UUV may be configured to cooperate with the node short-range navigation device during an end portion of the navigation path adjacent the frame.

An underwater communications network may include spaced apart nodes on a bottom of a body of water. The underwater communications network may also include fiber optic cabling connecting the spaced apart nodes. Each node may include a frame, a node short-range navigation device carried by the frame, and an unmanned underwater vehicle (UUV) carried by the frame after delivering a fiber optic cable along a navigation path from an adjacent node. The UUV may be configured to cooperate with the node short-range navigation device during an end portion of the navigation path adjacent the frame.

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.

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 location position system can include a plurality of beacons arranged a grid formation divided into a plurality of sub-grids. A mobile computing device can implement a location position application and can receive a radio signal from a particular beacon of the plurality of beacons. The radio signal can comprise a data component uniquely identifying the particular beacon, which can be used to identify a particular sub-grid of the plurality of sub-grids. An audio signal can be received from each of a set of sub-grid beacons associated with the particular sub-grid. Each audio signal can: (i) have a frequency in the frequency range of 16 kHz to 24 kHz and a transmission delay from a reference time, (ii) lack any additional identifying data, and (iii) be separately transmitted from the radio signal transmitted by the particular beacon. The mobile computing device can determine its position based on the received audio signals.

A location position system can include a plurality of beacons arranged a grid formation divided into a plurality of sub-grids. A mobile computing device can implement a location position application and can receive a radio signal from a particular beacon of the plurality of beacons. The radio signal can comprise a data component uniquely identifying the particular beacon, which can be used to identify a particular sub-grid of the plurality of sub-grids. An audio signal can be received from each of a set of sub-grid beacons associated with the particular sub-grid. Each audio signal can: (i) have a frequency in the frequency range of 16 kHz to 24 kHz and a transmission delay from a reference time, (ii) lack any additional identifying data, and (iii) be separately transmitted from the radio signal transmitted by the particular beacon. The mobile computing device can determine its position based on the received audio signals.

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 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 focus controlling component is configured to control a focus of a laser beam that passes through water and induces plasmas that emit signals. The focus of the laser beam is controlled such that the signals emitted by the induced plasmas interfere to form a combined signal that propagates in a desired direction.