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.

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.

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.

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.

A method is provided for localizing an underwater vehicle using acoustic ranging. The method includes receiving, using an acoustic receiver, a time series signal based on one or more acoustic signals transmitted from an acoustic source having a known location; determining a travel time of the waveform from the known location of the acoustic source to the acoustic receiver; and determining a range of the underwater vehicle with respect to the acoustic source based on the travel time of the waveform and a sound speed field taken along a ray trajectory extending from the known location of the acoustic source and intersecting with the acoustic receiver at an expected arrival time and depth of the acoustic signal at the underwater vehicle.

Systems and methods for driver identification using vehicle approach vectors are disclosed. An example disclosed vehicle includes a plurality of beacons configured to connect to a first mobile device and a second mobile device. The example vehicle also includes a plurality of ultrasonic sensors. The example vehicle includes a driver identifier configured to predict trajectories for the first and second mobile devices based on information received from the plurality of beacons and the plurality of ultrasonic sensors, and determine which one of the mobile devices is associated with a driver based on the predicted trajectories.

Systems and methods for driver identification using vehicle approach vectors are disclosed. An example disclosed vehicle includes a plurality of beacons configured to connect to a first mobile device and a second mobile device. The example vehicle also includes a plurality of ultrasonic sensors. The example vehicle includes a driver identifier configured to predict trajectories for the first and second mobile devices based on information received from the plurality of beacons and the plurality of ultrasonic sensors, and determine which one of the mobile devices is associated with a driver based on the predicted trajectories.

The present disclosure provides techniques for improving IMU-based gesture detection by a device using ultrasonic Doppler. A method may include detecting the onset of a gesture at a first device based on motion data obtained from an IMU of the first device. An indication of the detection of the onset of the gesture may be provided to a second device. Next, a first audio signal may be received from the second device. As a result, the gesture may be identified based on the motion data and the received first audio signal. In some cases, a first token encoded within the first audio signal may be decoded and the first token may be provided to a third coordinating device. A confirmation message may be received from the third coordinating device based on the first token provided and identifying the gesture may be further based on the confirmation message.

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.