A system and methods for estimating the location of a mobile device are disclosed. In accordance with one embodiment, a mobile device receives, at a first time t.sub.1, a wireless electromagnetic signal, where the wireless electromagnetic signal comprises a first identifier that identifies a first beacon that transmitted the wireless electromagnetic signal. The mobile device receives, at a second time t.sub.2, t.sub.2>t.sub.1, an ultrasound signal lacking an identification of the source of the ultrasound signal. A time difference of arrival (TODA) t.sub.2t.sub.1 is compared to a maximum TDOA. A location of the mobile device is estimated based on the TDOA only when the TDOA is less than or equal to the maximum TDOA.

A transmitter is provided that is capable of communicating with a management apparatus via a network and is configured to output a plurality of sound waves in a plurality of different directions. The transmitter includes a memory storing a program, and a processor configured to execute the program to implement processes of outputting a first sound wave including first unique information in a first output direction of the plurality of different directions, outputting a second sound wave including second unique information that differs from the first unique information in a second output direction that differs from the first output direction, and individually controlling the first sound wave output by the first sound wave output unit and the second sound wave output by the second sound wave output unit based on a request from the management apparatus.

A system and method for determining a presence of a mobile device located in a predetermined detection zone within a vehicle may include a plurality of transmitters located within the vehicle, in which each of the plurality of transmitters is configured to transmit an acoustic signal into an acoustic environment within the vehicle, and in which each of the acoustic signals comprises at least one ultrasonic pulse, a mobile device configured to periodically record sounds in the acoustic environment, and a processor configured to determine that a periodically recorded sound by the mobile device comprises each of the acoustic signals transmitted by the plurality of transmitters, determine a location of the mobile device within the vehicle based on the acoustic signals recorded by the mobile device, and determine that the location of the mobile device matches the predetermined detection zone.

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).