It seems that almost everyone has heard of GPS (Global Positioning System) in one form or another. The most well known GPS device is the car navigation system that shows and tells the driver through voice commands how to get to their desired pre-programmed destination. But if you’re wondering how these little technological wonders work then you’ve come to the right place.
A GPS receiver is an electronic device that uses the Global Positioning System to determine its exact location on earth with pin-point accuracy. This system is made up of the three parts; 27 satellites that send out continuous positioning signals, ground stations around the world that help synchronize the satellites, and various types of GPS receivers.
In this article we’re going to concentrate on how a GPS receiver works within this system since it’s the piece of the GPS puzzle that keeps you from getting lost. Its main function is to calculate its position on the earth using the signals that it receives from the satellite system.
To do this the receiver needs to lock onto the signals of at least 3 satellites. Once 3 or more satellites have been detected it then needs to determine the distance between the satellites and the distance between itself and each satellite. It then uses the basic math principles of triangulation or trilateration to compute its location on the earth’s surface.
The signals a GPS receiver uses to figure its location are radio signals transmitted by the satellites. These radio signals have three bits of information embedded in them; ephemeris data, almanac data, and a pseudorandom code. Using this information the GPS unit is able to triangulate its position and report that back to its user.
Accuracy is another question many first time users wonder about. The good news is GPS receivers are very accurate with the ability to pin-point your location to within a radius of 20 meters. There are ways to increase accuracy through the use of DGPS (Differential GPS) and WAAS (Wide Are Augmentation System) which can get within 3 meters of accuracy. Units with these two features normally cost more but the increase in accuracy can be well worth the cost.
There are many factors that can and do affect how accurately a GPS unit reports its position. These include:
1. The number of visible satellites
2. Signal delays caused as they pass through the earths atmosphere
3. Signals bouncing off of objects
4. Inaccurate clock in the GPS unit
5. Ephemeris errors
6. Satellites in poor positions
7. Satellite signals that are blocked because of terrain or manmade features
GPS is a great technology that has found its way into many everyday applications. Depending on your needs for keeping track of where you are there is sure to be a GPS receiver that fits the bill.
By: Andrew Bicknell
Posts Tagged ‘Electronic Device’
GPS Auto Tracker, Keeping Track of Your Vehicles
October 2nd, 2009
A GPS auto tracker system is an electronic device installed within or on a vehicle to enable the owner or a third party to track the vehicle’s location, speed, direction and disposition. GPS auto tracker systems use Global Positioning System (GPS) modules located within the electronic device for accurate location of the vehicle. Many systems also combine a communications component such as cellular or satellite transmitters to communicate the vehicles location. speed and direction to a remote user. The Gps auto tracker information is then viewed on electronic maps via the Internet or on your computer.
The shipping industry is the largest user of GPS auto tracker systems. Many large shipping companies with large fleets of vehicles needed a vehicle tracking gps system to determine the location of each vehicle was at any given time. GPS auto tracker systems are becoming more common and can be found in consumers vehicles as driver surveilance and performance units as well as vehicle theft and retrieval devices. Police can follow the signal emitted by the tracking system to locate a stolen vehicle. In addition parents can determine if their sons or daughters are driving in a responsible manner. In addition there is also a new line of GPS Auto Tracker systems that are used to keep track of a childs where abouts even if they are out of the vehicle.
GPS auto tracker systems are now using a type of automatic vehicle location (AVL) to allow for easy location of the vehicle. The GPS satellite system was built and is maintained by government and is available at no cost to civilians. This makes vehicle tracking gps technology very inexpensive. Other older AVL systems do not require the antenna to be in direct line of sight with the sky. Older ground based systems such as LORAN and LoJack tracking units use radio frequency (RF) transmitters which will transmit through walls, garages, or buildings. Police vehicles around the world have a form of AVL tracking as standard equipment in their units.
Standard GPS auto tracker systems charge the user a monthly fee for a package that includes the hardware, installation and download or mapping as part of the tracking service. Passive GPS auto tracker units are paid for upon installation and will continue to work for the life of the vehicle. Active GPS auto tracker systems as well as the ground based cell phone and Loran systems provide real time data. A commercial fleet manager may want 5 minute updates, telling whether a vehicle is on route or off, engine status, brake status, container status as well as vehicle speed and direction. Newer smaller and more efficient GPS auto tracker units are becoming available to the consumer market. It will be just a matter of time before every vehicle on the road will have the hardware necessary for GPS Auto Tracker Systems.
By: Jim Kesel
