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. Beacons are scheduled to transmit independent of the location of listening devices in the system. Listening devices may receive multiple encoded radio frequency pulses (RF) prior to a single acoustic pulse, and then resolves which RF pulse corresponds to the acoustic pulse using triangulation techniques.

A range-finding and/or object-positioning system comprises one or more target devices; one or more reference devices communicating with said one or more target devices via one or more wireless signal sets, each wireless signal set comprising at least a first-speed signal having a first transmission speed and a second-speed signal having a second transmission speed, and the first transmission speed being higher than the second transmission speed; and at least one processing unit performing actions for determining at least one distance between one target device and one reference device based on the time difference between the receiving time of the first-speed signal and the receiving time of the second-speed signal of the wireless signal set communicated between said reference and target devices.

Provided is an ultrasonic-wave communication system where the influence of ambient noise and the Doppler effect are suppressed and where a user of a portable terminal is prevented from hearing unwanted sound. After performing encryption processing of predetermined information such as store information, a beacon 5 sends out predetermined-information-containing beacon information of one channel as ultrasonic waves into the salesroom 3 by combining a control carrier, a first carrier, and a second carrier in such a way that a first carrier signal and a second carrier signal are output between control carrier signals a number of times according to the predetermined information and that a state where the first carrier signal and/or the second carrier signal is output is maintained.

Systems and methods for identifying device location are provided. The method can include providing, by a mobile computing device, at least a first ultrasonic signal to a first and a second self-organizing beacon device. The method can include receiving, by the mobile computing device, a first radio frequency signal including the location of the first beacon device and a second radio frequency signal including the location of the second beacon device. The method can further include determining a first time-of-flight associated with the first beacon device and a second time-of-flight associated with the second beacon device. The method can include determining a location of the mobile computing device based at least in part on the first time-of-flight, the second time-of-flight, the location of the first beacon device, and the location of the second beacon device.

Systems and methods for identifying device location are provided. The method can include providing, by a mobile computing device, at least a first ultrasonic signal to a first and a second self-organizing beacon device. The method can include receiving, by the mobile computing device, a first radio frequency signal including the location of the first beacon device and a second radio frequency signal including the location of the second beacon device. The method can further include determining a first time-of-flight associated with the first beacon device and a second time-of-flight associated with the second beacon device. The method can include determining a location of the mobile computing device based at least in part on the first time-of-flight, the second time-of-flight, the location of the first beacon device, and the location of the second beacon device.

Examples of the disclosure relate to apparatus (101) for positioning mobile devices (105). The apparatus (101) comprises means for: obtaining a time of arrival of at least one audio signal (131) at a mobile device (105), wherein the audio signal (131) is generated with a photoacoustic effect; and using the time of the arrival of the audio signal (131) to estimate a location of the mobile device (105).