There are a whole lot of benefits possible around location based services on mobile phones. Before we go on to understand sample of such services and the benefits let’s first understand how the location of a mobile device is detected. Currently, there are two ways in which location of the mobile phone is established: A-GPS vs GPS GPS stands for Global Positioning System. Standalone/autonomous GPS operation uses radio signals from satellites, therefore, a GPS device communicates with 4 or more satellites to determine its exact location coordinates (latitude and longitude) anywhere on Earth. It works in any weather as long as the device has a clear line of sight to the satellites. A-GPS stands for assisted global positioning system, while just regular GPS is non-assisted. GPS satellites circle the earth twice a day in an orbit. These satellites continuously send information to the earth via radio waves. Messages transmitted by the satellites include (a) the time the message was transmitted, (b) the ephemeris or the information about the orbit, and (c) the almanac or the health and rough orbits of all the satellites. GPS receivers use these signals by calculating the time at which the signals were sent by the satellites and time at which they were received on Earth. Once the GPS receiver knows the position of at least four satellites and the transmit time of each (this is called time to first fix, TTFF), it is able to lock its own location. This method of computing is called trilateration. This initial TTFF is often called a cold start, it can take anywhere from 30 seconds to a couple of minutes to acquire a signal. That time is dependent on ones’ location, amount of […]
