Disclosed are a system for identifying the position of mobile object, comprising a positioning module, a set of beacons and processor configured to determine the position of the positioning module based on the data gathered from the interaction between the positioning module and each one of the set of beacons. More specifically, the limited area positioning system utilizes signal emitted from the positioning module and the signals emitted from the each of the beacons in response to the signal from the positioning module. Using the signals transmitted from the positioning module and the beacons, at least three circles can be formed, and the limited area positioning system determines the intersecting point of those three circles as the position of the positioning module.

A communication device including a clock, a memory, and at least one processor is disclosed. The at least one processor is configured to execute instructions stored in the memory that cause the at least one processor to perform operations including receiving at least one message from a second communication device of a plurality of communication devices over a preconfigured time duration, determining a first local time of the clock of the communication device at which the at least one message from the second communication device is received, and determining a sync-time of the second communication device based on the at least one message from the second communication device. The operations include mapping the sync-time of the second communication device based on the first local time and the determined sync-time of the second communication device and adjusting a sync-time of the communication device based on the second local time.

A communication device including a clock, a memory, and at least one processor is disclosed. The at least one processor is configured to execute instructions stored in the memory that cause the at least one processor to perform operations including receiving at least one message from a second communication device of a plurality of communication devices over a preconfigured time duration, determining a first local time of the clock of the communication device at which the at least one message from the second communication device is received, and determining a sync-time of the second communication device based on the at least one message from the second communication device. The operations include mapping the sync-time of the second communication device based on the first local time and the determined sync-time of the second communication device and adjusting a sync-time of the communication device based on the second local time.

An electronic apparatus connectable to an external electronic apparatus includes a wireless communicator configured to receive a wireless signal from the external electronic apparatus; a sound wave receiver configured to receive a sound wave signal from the external electronic apparatus; and a controller configured to, based on an initial distance between the external electronic apparatus and the electronic apparatus measured by using the wireless signal and the sound wave signal, measure a propagation constant between the external electronic apparatus and the electronic apparatus, and when the initial distance between the external electronic apparatus and the electronic apparatus is changed to a first distance, measure the first distance based on the propagation constant.

An electronic apparatus connectable to an external electronic apparatus includes a wireless communicator configured to receive a wireless signal from the external electronic apparatus; a sound wave receiver configured to receive a sound wave signal from the external electronic apparatus; and a controller configured to, based on an initial distance between the external electronic apparatus and the electronic apparatus measured by using the wireless signal and the sound wave signal, measure a propagation constant between the external electronic apparatus and the electronic apparatus, and when the initial distance between the external electronic apparatus and the electronic apparatus is changed to a first distance, measure the first distance based on the propagation constant.

An indoor location system has acoustic wave emitters, electromagnetic emitters, and a mobile device. Each acoustic wave emitter is configured to emit an acoustic wave having an acoustic wave frequency and wavelength, and an electromagnetic signal that includes electromagnetic emitter data related to that electromagnetic emitter and data indicative of a frequency and/or wavelength of an acoustic wave emitted by the acoustic wave emitter that is associated with that electromagnetic emitter. The mobile device is configured to detect the acoustic waves and to receive the electromagnetic signals, and to determine the frequency and/or wavelength of the detected acoustic wave and to compare the determined acoustic wave frequency and/or wavelength with the data included in each received electromagnetic signal, thereby to determine which received electromagnetic emitter data was included in the electromagnetic signal which also included the data indicative of the frequency and/or wavelength of the detected acoustic wave.

An indoor location system has acoustic wave emitters, electromagnetic emitters, and a mobile device. Each acoustic wave emitter is configured to emit an acoustic wave having an acoustic wave frequency and wavelength, and an electromagnetic signal that includes electromagnetic emitter data related to that electromagnetic emitter and data indicative of a frequency and/or wavelength of an acoustic wave emitted by the acoustic wave emitter that is associated with that electromagnetic emitter. The mobile device is configured to detect the acoustic waves and to receive the electromagnetic signals, and to determine the frequency and/or wavelength of the detected acoustic wave and to compare the determined acoustic wave frequency and/or wavelength with the data included in each received electromagnetic signal, thereby to determine which received electromagnetic emitter data was included in the electromagnetic signal which also included the data indicative of the frequency and/or wavelength of the detected acoustic wave.

A method for testing a structure includes steps of: identifying a three-dimensional position of a surface of the structure relative to a reference frame; transmitting laser light from an output of a transmitter onto the surface of the structure to form ultrasonic waves in the structure and to detect a response to the ultrasonic waves; based on the three-dimensional position of the surface, moving the laser light over the structure along a scan path so that the output of the transmitter is located at a constant offset distance from the surface and that the laser light, transmitted from the output of the transmitter, is directed onto the surface at a constant angle of projection; and based on the response to the ultrasonic waves, determining whether an inconsistency is present in the structure.

A method includes recording a first timestamp of a detection with a first sensor array of a first physical property of an event; determining a direction of the event, based on the detection with the first sensor array; recording a second timestamp of a detection with a second sensor array of a second physical property of the event; determining a distance of the event from the first and second sensor arrays, based on the first timestamp and the second timestamp; determining the event, based on the first physical property and the second physical property; and taking an action based on the event.

A method includes recording a first timestamp of a detection with a first sensor array of a first physical property of an event; determining a direction of the event, based on the detection with the first sensor array; recording a second timestamp of a detection with a second sensor array of a second physical property of the event; determining a distance of the event from the first and second sensor arrays, based on the first timestamp and the second timestamp; determining the event, based on the first physical property and the second physical property; and taking an action based on the event.