Desarrollo de un sistema para la transmisión de la ubicación de un teléfono inteligente hacia los servicios de emergencia por medio de tonos DTMF

Abstract

Obtaining the location of a user who calls emergency services is important in order

to give them the urgent care they need. The call originating from a mobile phone ma- kes discerning this information difficult. The user might not know his location or can’t

communicate it, because of their condition or due to the situation they’re in. Modern cellphones can obtain their position from the O.S.’s location services. Meanwhile, the

DTMF tone system assigns two sinusoidal audio signals to each digit of a phone key- pad; this is used to communicate with various automatic phone systems: to navigate

through menus, as well as to enter various information. In the present undergradua- te thesis project, a system is developed to transmit the geographic coordinates of a

mobile phone. The system consists of an Android application that obtains the location coordinates from the mobile phone’s O.S., encodes these with the use of DTMF tones, which are then played in the audio of the ongoing call. These tones are received by an electronic device that then decodes the tones to recover the original geographic coordinates of the user. The device displays the coordinates on a LCD screen, as well as transmits a URL with the coordinates to a computer, when the URL is clicked on, the location of the user is displayed in Google Maps. A series of trials are carried out under various mobile phone coverage levels, at three different locations. The results demonstrate that this system performs with a high degree of fidelity.