Cell Phone GPS Tracking Introduction

Mobile phone GPS is what consumers generally think of whenever investigating tracking cell phones. GPS (Global Positioning System) using satellites is the most well known and more accurate way of tracking. However, GPS needs satellites to be in direct line of site from the handset. It doesn’t work as well indoors or in dense metropolitan areas. If the cell phone is inside a structure, for example your school, restaurant, or often sitting in an automobile the signals may not reach the smartphone. Occasionally heavy cloud cover and dense foliage impedes with reception. Some cell phones can preserve the last identified GPS position, others may not.

A lot of the discussion surrounding cell 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 determine three-dimensional location (latitude, longitude, and altitude) plus precise time. GPS is an acronym for Global Positioning System and is a network that is made up of 3 main segments: Space Segment, Control Segment and User Segment.

The GPS Space Segment consists of twenty-four to thirty-two satellites that orbit the earth in medium earth orbit MEO. These satellites are also known as as the GPS Constellation, and they make an orbit once every 12 hours. They are not parked over one spot, they travel at over 7,000 mph. GPS satellites are solar powered but have battery reserve for when they are in the earth?s shadow. They are placed 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 runs out.

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 offset and are in equilibrium. This is the ideal location to park a stationary satellite. The earth rotates at about 1,000 miles an hour, and because of their high earth orbit the geo-synchronous satellites need to travel at about 7,000 mph to keep position. This is approximately 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 incorporates Master Control Station, an Alternate Master Control Station, and a host of dedicated and shared Ground Antennas and Monitor Stations that work together to ensure the satellites are working to specification and the information they send to earth is accurate.

The GPS User Segment consists of of GPS receivers taking the shape of cell phones 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 often take a long time to become ready to use after being turned on because it must acquire some basic information in addition to capturing GPS satellite signals. This delay is sometimes caused if the GPS cell phone has been turned off for days or weeks, or has been transported a far distance while unused for. The GPS must update its almanac and ephemeris data and store it in memory. The GPS almanac is a set of data that every GPS satellite transmits. When a GPS receiver has current almanac data in memory, it can capture satellite signals and calculate initial location more quickly.

Another way of determining cell phone position is Triangulation or Mobile Location Services (MLS). Cell Tower Triangulation uses signal analysis data to determine the time it takes signals traveling from your cellular phone to no less than 3 cell towers to calculate position.

With Mobile Location Services (MLS), the GSM cell network provider utilizes triangulation algorithms to compute the position of the smartphone, its accuracy is proven to be much worse than that of GPS. MLS is further affected by factors similar to GPS in the sense of the barriers affecting 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.

Cell Phone GPS Tracking Introduction