GPS: Global Positioning System – A system that collects data from several stationary satellites positioned in Earth's orbit to provide you with information for different end uses, including tracking of any object, aiding the user with navigation to any place, or to measure and map any area. What started as a system for helping US defense now extends into almost every field of life. This includes gaming (Geocache: a treasure hunt using GPS. The link takes you to an article that describes the game). Read our Bright Hub article for information on how GPS operates.
GNSS: Global Navigation Satellite Systems - A system of satellites, interlinked to provide continuous signals containing data about longitude, latitude, elevation (compared to sea-level) and time. A GNSS system also sends out other information as well, such as "ionosphere disturbance co-efficient" to enable GPS units calculate and present GPS users with better accuracy of GPS. At the moment, the only fully-functional GNSS is NAVSTAR, developed by US Defense. Other countries also have their own GNSS but they are still in the process of completion. Read our Bright Hub article for more details on GNSS.
GPS Unit: Any device capable of receiving GPS data to track your location, traffic information, help navigate to a particular place, or virtually anything involving distance and mapping. A GPS unit can be a standalone device, part of your cell phone, or incorporated into your palmtops. The main components of the GPS unit are the GPS antenna, GPS signal receiver, GPS signal processor, and finally the GPS display (OSD – On Screen Display). For more details on components of a GPS unit, click here.
1D: One Dimensional – A GPS unit that can receive data only about one of the following three: longitude, latitude, or elevation. As such, no commercial GPS unit employs 1D as the information is not enough to allow you to use your GPS unit. There is use in a research setting.
2D: Two Dimensional – A GPS unit that can receive data only about longitude and latitude. Such devices are used in areas that do not require enhanced accuracy of GPS. One example of such device is a GPS unit used to watch a stationary object for security purposes. If the object is moved, the unit triggers an alarm, announcing attempted theft of the object.
3D: Three Dimensional – GPS units capable of receiving just enough data to track any object. The three planes represent longitude, latitude, and elevation (compared to sea-level). However, the data is not as accurate while moving because it takes time for the signal to reach the GPS unit. If it is moving, the data your unit gets may be a few inches/miles behind depending upon the speed at which the GPS unit is moving.
4D: Four Dimensional – The most common (commercial) GPS units used as GPS technology. These commercially available devices can receive the time of signal along with the data received under 3D. The satellite sending the 3D data includes a time-stamp on the signal so that your unit can offer precise information for almost any purpose: tracking moving objects, navigation, and mapping.
L1, L2, and L2C: The frequencies on which, the GPS system sends data to GPS units. The L1 frequency is for civilians while L2 is reserved for defense only. The L2 frequency employs high encryption in addition to extra information to compute enhanced accuracy of GPS. As the need for precise calculations picked up in different fields of science, the US Defense system allowed a part of L2 signal for civilians (L2C). Most of the commercial GPS units are now using L2C for operations for reducing GPS error possibilities and increasing the accuracy of GPS. General L1 frequency offers two types of signals: C/A Code and P Code Signals.
The C/A (Coarse Acquisition Code) is slightly less strong than the P Code (Precision Code). The commercial GPS units in the market may use both C/A and P Codes to check the difference in measurements and thereby offer you enhanced precision of GPS. The difference in C/A and P Code can be further understood upon studying this summary.
L1C (enhanced L1 signal code for civilians) is yet another signal type in the works and is due in 2013. The L1C is the brainchild of GALILEO, the European GNSS. Codes for processing GPS signals are developed by GPS vendors and this determines the cost of the GPS units.
The next page deals with GPS acronym meanings encountered in the GPS technology ads that mention accuracy of GPS and GPS safety standards.
