A Short Intro To Mobile Phone GPS Tracking

Much of the discussion dealing with GPS tracking, mobile GPS and mobile phone track software could be helped by a GPS Satellite primer.

GPS satellites broadcast signals from space that GPS receivers utilize to provide three-dimensional location (latitude, longitude, and altitude) plus precise time. GPS is an acronym for Global Positioning System and is a network that is composed of 3 primary segments: Space Segment, Control Segment and User Segment.

The GPS Space Segment includes twenty-four to thirty-two satellites that orbit the earth at a height of about 12,000 miles. These satellites are referred to as the GPS Constellation, and they are orbiting once every 12 hours. They are not geosynchronous, they travel at over 7,000 mph. GPS satellites are solar powered but have battery reserve for when they are on the dark side of the earth. They are positioned so that there are at least 4 satellites ?visible? from any point on earth. Small rocket boosters on each satellite keep them properly positioned. The satellites last about ten years until all their fuel is exhausted.

GPS Satellites are not communications satellites. Geostationary or communications satellites are at a much higher orbit of about 22,300 miles above the equator. These satellites are used for weather forecasting, satellite TV, satellite radio and most other types of global communications. At exactly 22,000 miles above the equator, the earth’s gravitational force and centrifugal forces are canceled and are in balance. This is the ideal location to place a communications satellite. The earth rotates at about 1,000 miles an hour, and because of their high earth orbit the earth-synchronous satellites need to travel at about 7,000 mph to sustain position. This is just about the same speed as GPS satellites, but since geostationary satellites are 10,000 miles further away they don?t move relative to the earth.

The GPS Control Segment consists of Master Control Station, an Alternate Master Control Station, and numerous dedicated and shared Ground Antennas and Monitor Stations that work together to ensure the satellites are working to specification and the information they beam down to earth is accurate.

The GPS User Segment incorporates of GPS receivers taking the shape of devices and , laptops, in-car navigation devices and hand-held tracking units along with the people that use them, and the software applications that make them function.

GPS receivers, no matter whether inside of a cell phone, or simply a spucific Portable gps tracking system, calculate location by way of precisely timing the signals transferred by GPS satellites. This data provides the moment the message was transmitted, accurate orbital details (technically called the ephemeris), and also the general system health and determined orbits of all GPS satellites (technically referred to as the almanac).

Another way of determining device location is Triangulation or Mobile Location Services (MLS). Cell Tower Triangulation uses signal analysis data to calculate the time it takes signals to travel from the phone to a minimum of three cell towers to judge position.

With Mobile Location Services (MLS), the GSM cellular network provider uses triangulation techniques to determine the location of the device, its accuracy is proven to be much worse than that of GPS. MLS is further impacted by factors similar to GPS in the sense of the barriers impeding signal strength and the density of GSM towers to help in the triangulation calculation. In remote areas position accuracy may be off as much as a mile.

A Short Intro To Mobile Phone GPS Tracking