A Look At Smartphone GPS Tracking

Much of the discussion dealing with cell tracking, mobile GPS and cell 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 stands for Global Positioning System and is a system that is made up of 3 main segments: Space Segment, Control Segment and User Segment.

The GPS Space Segment made up of 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 make an orbit once every 12 hours. They are not geosynchronous, but rather move at over 7,000 mph. GPS satellites are solar powered but have battery backup 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 have a lifetime of about 10 years until all their fuel is exhausted.

GPS Satellites are not communications satellites. Geostationary or communications satellites are parked in space 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 equilibrium. 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 geo-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 earth-synchronous satellites are 10,000 miles further away they stay in place relative to the earth.

The GPS Control Segment made up of 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 functioning correctly and the data they send to earth is accurate.

The GPS User Segment is comprised of of GPS receivers taking the shape of mobile 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 it’s turned on because it must acquire some basic information in addition to capturing GPS satellite signals. This delay is sometimes caused when the GPS smartphone has been turned off for days or weeks, or has been transported a significant distance while turned off 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 acquire satellite signals and determine initial position faster.

Another method of calculating smartphone position is Triangulation or Mobile Location Services (MLS). Cell Tower Triangulation utilizes signal analysis data to compute the time it takes signals traveling from your smartphone to at least three cell towers to estimate position.

With Mobile Location Services (MLS), the GSM cellular network provider utilizes triangulation algorithms to compute the position of the mobile phone, its accuracy is proven to be less than than that of GPS. MLS is further impacted by the same issues as GPS in the sense of the barriers impeding signal strength and the density of GSM towers to assist in the triangulation calculation. In rural areas location accuracy may be off as much as a mile.

A Look At Smartphone GPS Tracking