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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.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006


McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


Abbr. for “gallons per second.”
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.


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(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). Originally created for the military, today, GPS receivers are built into all smartphones and millions of cars and trucks. See in-dash navigation, CarPlay, Android Auto and portable GPS.

GPS vs. the "Nav"
Technically, the GPS is the satellite system, whereas a "navigation" system or "nav" is the GPS receiver that picks up the signals. In practice, most people refer to their navs as their GPS.

Three or Four Signals Are Required
At least four satellites are on the horizon at all times, which is sufficient to compute the current latitude, longitude and elevation anywhere on earth to within 15 to 70 feet (see latitude). If only three signals are present due to interference, elevation cannot be derived. If fewer than three, the location cannot be computed unless the nav is built into the vehicle and interfaces with the speedometer (see in-dash navigation).

The Satellite System
In six different orbits approximately 12,500 miles above the earth, 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 (L1: 1575.2 MHz; L2: 1227.6 MHz). Most navs pick up L1, while more advanced receivers pick up both for greater accuracy.

The nav 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 nav computes the current coordinates using trilateration, a method similar to how ship captains navigated for centuries (see triangulation).

First Launched in 1978
In this decades-old system, satellites are periodically replaced. In addition, worldwide government and commercial monitoring networks use earth stations to improve accuracy; for example, enabling farm equipment to plant ultra-precise rows of crops (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 Nav
In 1996, Sony's NVX-F160 was one of the first vehicle navigation systems, and it was able to find the nearest restaurant and hotel. (Image courtesy of Sony Corporation.)

GPS in the Woods
Portable navigation works everywhere. The flat object pointing up is the antenna. See portable GPS.

Navigation App in 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).

Navigation App in 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).

It Doesn't Get Better Than This
Tesla's navigation system is unlike any other. The 17" touchscreen displays more map area than any other nav screen.
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References in periodicals archive ?
Here WeGo (which was originally developed for the Windows Phone platform by Nokia) is a free app that offers turn-by-turn directions for drivers, pedestrians, cyclists and public transit riders.
Though the convenience and pure aesthetics, relying on turn-by-turn directions, coming from a built-in seven-inch display is an addition we can only welcome.
Mixer drivers can then follow voice-guided, turn-by-turn directions to maneuver around road delays, helping them travel to job sites on time.
Sat-nav firm Garmin has made a portable head-up display ( HUD) for cars that projects turn-by-turn directions on to a vehicle's windscreen.
When turn-by-turn directions are announced, the smartphone will automatically fade out any music from the phone.
The ISOLynx controller also features FieldLynx telematics remote monitoring, diagnostics, and fleet management, including turn-by-turn directions and wireless data transfer in real time.
Waze is a community-based traffic and navigation app that uses the data of other Waze users to identify slow spots and accidents, while providing you with audible turn-by-turn directions to avoid them.
Apple launched a new version of Maps last week, and the latest version was built from the "ground up," to include new features such as turn-by-turn directions, voice integration, and vector-based maps, Cook said.
Also, the app will give you turn-by-turn directions to the gas station so you wonOt waste petrol driving around looking for a reasonably priced station.
Include offerings that complement the wayfinding function, such as store descriptions, hours of operation, or printable turn-by-turn directions.
In driving mode, the unit works like a regular, windshield-mounted automotive GPS with spoken turn-by-turn directions. But when you go off the beaten path, the Nuvi 500 seamlessly turns into a backcountry navigator complete with pre-loaded U.S.
Many have experienced turn-by-turn directions given by the navigation system and found it as a very useful tool to save time and increase efficiency.