GPS – A Short Introduction
GPS, which stands for Global Positioning System, is a satellitenavigation system that can ascertain the latitude and longitude of a GPS receiver device on the Earth. The GPS consists of more than two dozen global positioning satellites orbiting the earth. Each satellite transmits radio signals, which can help determine the location, speed and direction of travel of users equipped with GPS receivers. To ensure that the whole world is covered by the constellation of the GPS satellites, they are so arranged that four satellites are positioned in each of six orbital planes.
A GPS tracking unit can determine the precise location of any individual or vehicle carrying the GPS receiver. Data about location and other aspects can be stored in various forms, depending on the type of tracking unit.
The location of the object or individual being tracked is often recorded at regular intervals. Recording of an object can take place within the GPS receiver unit, or can be transmitted to a central location such as a database, where it can be accessed either via mobile technology or over the internet. GPS tracking systems can typically be viewed in real-time and have a map in the background to display the current location of an object.
Three Types of GPS Tracking Units
GPS tracking units are divided into three categories, based on the techniques of data logging and retrieval.
A GPS data logger logs the position of the object at regular intervals and stores the information in flash-based memory. Data on the memory can be retrieved or transferred to other stores with the help of available USB connectivity. Such devices are suitable for long distance hikers and cycling enthusiasts, who can make use of the logging facility to chalk out future routes to be followed.
The GPS data pushers are popular for security purposes. This unit sends data from the device to a central database at regular intervals, updating information on location, direction, speed and distance.
Such devices are suited for monitoring fleets of trucks and delivery vehicles. Vehicles can be located instantly in order to carry out effective supervision and prevent theft.
Since it is easy to track movements of individuals or vehicles carrying valuable items, GPS data pushers are often used for spying.
A GPS data puller allows the user to ‘pull’ data from the receiver as frequently as needed. The device remains on at all times. Though it is not as commonly used as the pusher device, it is particularly useful for tracing stolen goods. A mobile phone with integrated GPS can reply to an SMS from the data puller. This technology finds use in situations where tracking is required to be done only rarely.
Counter Measures to GPS Tracking
The subject of GPS tracking has been hotly debated, because of the potential breaches of privacy.
There are not many counter measures that can be taken to guard against unwanted GPS tracking. One possible counter measure is jamming the GPS signal; however, this is illegal in many countries, because of the possibility of affecting a wide range of signals that might be legitimately used, as those used by aircraft. Another counter measure is to use a device that can ascertain when radio signals are being sent or if a GPS device is present on a person or asset. However, most cell phones and other consumer electronics usually include controls to disable the function of GPS tracking.