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see navigation satellitenavigation satellite,
artificial satellite designed expressly to aid the navigation of sea and air traffic. Early navigation satellites, from the Transit series launched in 1960 to the U.S. navy's Navigation Satellite System, relied on the Doppler shift.
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See global positioning system.



Abbr. for “gallons per second.”



(1) (General Print Server) An IBM mainframe feature that lets TN3270 clients access LPD/LPR printers via the SNA/VTAM network. See TN3270 and VTAM.

(2) (Global Positioning System) A satellite-based radio navigation system run by the U.S. Department of Defense, officially known as NAVSTAR GPS (see also GLONASS, Galileo and Beidou). Created for the military, the GPS system is not only used by consumers, but in numerous industries, including agriculture, oil, gas, mining and construction.

For consumers, it means no more asking directions when GPS receivers are built into vehicles (see in-dash navigation) or into mobile units that can be taken anywhere (see portable GPS, CarPlay and Android Auto).

Three or Four Satellite Signals Required
The GPS system was designed so that signals from at least four satellites would be on the horizon at all times, sufficient for the GPS receiver to compute the current latitude, longitude and elevation anywhere on earth to within a range of 15 to 70 feet (see latitude). If signals from only three satellites are received, the location can be derived, but not elevation. If less than three, the system cannot compute its current location unless it is tied to the speed of the vehicle (see in-dash navigation).

The Satellite System
In six different orbits approximately 12,500 miles above the earth, the system's 24 medium-earth orbit (MEO) satellites circle the earth every 12 hours. They constantly transmit their current time based on atomic clocks and current location on two frequencies in the L-band labeled L1 (1575.2 MHz) and L2 (1227.6 MHz). Most receivers pick up L1, while more advanced receivers pick up both signals for greater accuracy by determining and removing ionospheric delays.

A GPS receiver calculates the distance to the satellites by comparing the times the transmitted signals were sent with the times received. By knowing the precise locations of the satellites at any given moment, the receiver uses trilateration, the navigation technique of ship captains for centuries, to pinpoint its own location. See triangulation.

First launched in 1978, GPS satellites have been replaced several times with newer models. There are also numerous government and commercial monitoring networks around the world that use earth-based reference stations to improve accuracy. For example, in agriculture, such systems enable farm equipment to automatically plant ultra-precise rows of crops within inches (see GPS augmentation system). See social navigation, vehicle tracking, reality view, GPS augmentation system, mobile positioning, LORAN, MEO, GNSS, Galileo and geocaching.

An Early Car System
In 1996, Sony's NVX-F160 was one of the first vehicle GPS navigation systems. It could direct you to the nearest restaurant, hotel or other point of interest. (Image courtesy of Sony Corporation.)

GPS in the Woods
Portable navigation systems work anywhere. The flat object pointing up at the top of this unit is the antenna. See portable GPS.

GPS on a Laptop
The Delorme Street Atlas offers extensive details including satellites in range (#15 just lost signal), elevation (Elv), azimuth (Az) and signal-to-noise ratio (dB). NET means: N=navigation satellite, E=ephemeris data available and T=being tracked (yellow object on dashboard is the GPS antenna).

GPS on a Laptop
The Delorme Street Atlas offers extensive details including satellites in range (#15 just lost signal), elevation (Elv), azimuth (Az) and signal-to-noise ratio (dB). NET means: N=navigation satellite, E=ephemeris data available and T=being tracked (yellow object on dashboard is the GPS antenna).
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Many runners find that the newer model GPS units regularly deliver distances within .
It was Jenn's inquiry that led to my early spring stomp in the woods and to changes at AMERICAN FORESTS as the organization realizes the benefits GPS coordinates can offer.
Would you want a dime-size computer chip implanted under your skin that uses GPS to track your travels?
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Matthew Phillips, SVP of CSR's Mobile Handset Connectivity strategic business unit, commented, "At $5-$10, current GPS solutions are too expensive and just not practical for mainstream cellphone applications" Phillips continued, "There are also performance restrictions in terms of both handset and network that have meant that the technology is not appropriate for the mobile platform.
The "Global Positioning Services: Emerging Technological Trends" report provides an in-depth vision of the market scenario and the varied application growth opportunities influenced by the technological advancement in the field of GPS services.
Commenting on this innovative combined offer, Philippe Guillemette, Wavecom Vice President of Marketing and CTO said, "We see the demand for combining GPS with cellular wireless technology increasing exponentially for a wide variety of applications.
BENDIGO, Australia -- AutoFarm([R]), the leader in GPS precision farming, today announced it has finalised a strategic investment in gps-Ag([R]).
The Hybrid Positioning Module is the product of intense, dedicated work to develop and refine TV-positioning technology and then to tightly integrate it with a world-class Assisted GPS solution from Global Locate," commented Rosum CEO Skip Speaks.