Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. GPS satelliteEven fixed systems may use GPS, in order to get precise time. This antenna is mounted on the roof of a hut containing a scientific experiment needing precise timing.

Discover great deals on the many hard to find and one of a kind items available only on ebay!


This site contains sponsored affiliate links.

GPS

The Global Positioning System, usually called GPS (the US military refers to it as NAVSTAR GPS - Navigation Signal Timing and Ranging Global Positioning System), is the only operational satellite navigation system. more...

HomeHome
ComicsComics
ComputersComputers
ElectronicsElectronics
BlackberryBlackberry
BluetoothBluetooth
DVD PlayerDVD Player
GPSGPS
iPodiPod
Metal DetectorMetal Detector
mp3 Playermp3 Player
MoviesMovies
TelevisionTelevision
ToysToys
Video GamesVideo Games


For a list of other proposed and partially developed systems, including Russia's RONASS and Europe's Galileo, see satellite navigation system.

Satellite Navigation Systems can be used for determining one's precise location and providing a highly accurate time reference almost anywhere on Earth or in Earth orbit. The accuracy of the GPS signal itself is about 5 meters (16 ft) as of 2005 and has steadily improved over the last 15 years. Using differential GPS and other error-correcting techniques, the accuracy can be improved to about 1 cm (.4 in) over short distances.

The GPS system was designed by and is controlled by the United States Department of Defense and can be used by anyone, free of charge. The GPS system is divided into three segments: space, control and user. The space segment comprises the GPS satellite constellation of at least 24 satellites in an intermediate circular orbit (ICO) . The control segment comprises ground stations around the world that are responsible for monitoring the flight paths of the GPS satellites, synchronizing the satellites' onboard atomic clocks, and uploading data for transmission by the satellites. The user segment consists of GPS receivers used for both military and civilian applications. A GPS receiver decodes time signal transmissions from multiple satellites and calculates its position by trilateration.

Daily management of the GPS satellite constellation is conducted by the 2d Space Operations Squadron at Schriever Air Force Base. The cost of maintaining the system is approximately US$400 million per year, including the replacement of aging satellites. The first GPS satellite was launched in February 1978, and the most recent launch was in September 2005. The oldest GPS satellite still in operation was launched in February 1989.

Technical description

The system consists of a constellation of at least 24 satellites in 6 orbital planes. The GPS satellites were initially manufactured by Rockwell and now manufactured by Lockheed Martin. The first was launched in February 1978, and the most recent was launched September 25, 2005. Each satellite circles the Earth twice every day at an altitude of 20,200 kilometres (12,600 miles). The satellites carry atomic clocks and constantly broadcast the precise time according to their own clock, along with administrative information including the orbital elements of their own motion, as determined by a set of ground-based observatories.

The receiver does not need a precise clock, but does need a clock with good short-term stability and the ability to receive signals from four satellites in order to determine its own latitude, longitude, elevation, and the precise time. The receiver computes the distance to each of the four satellites from the difference between local time and the time the satellite signals were sent (this distance is called a pseudorange). It then decodes the satellites’ locations from their radio signals and an internal database. The receiver should now be located at the intersection of four spheres, one around each satellite, with a radius equal to the time delay between the satellite and the receiver multiplied by the speed of the radio signals. Because the receiver does not have a very precise clock it cannot compute the time delays. However, it can measure with high precision the differences between the times when the various messages were received and hence use multilateration to accurately locate itself. This yields 3 hyperboloids of revolution of two sheets, whose intersection point gives the precise location of the receiver. This is why at least four satellites are needed: fewer than 4 satellites yield 2 hyperboloids, whose intersection is a curve; it is impossible to know where the receiver is located along the curve without supplemental information, such as elevation. If elevation information is already known, only signals from three satellites are needed (the point is then defined as the intersection of two hyperboloids and an ellipsoid representing the Earth at this altitude).

Read more at Wikipedia.org


[List your site here Free!]

Samsung Galaxy S21 5G Unlocked G991U 128Gb Android Smartphone Very GoodSamsung Galaxy S21 5G Unlocked G991U 128Gb Android Smartphone Very Good $179.99 New ListingiPhone Xs - 64Gb - Unlocked (Read Description) Cj1021New ListingiPhone Xs - 64Gb - Unlocked (Read Description) Cj1021 $306.00
Celestron 93969 SkySync Gps AccessoryCelestron 93969 SkySync Gps Accessory $179.99 Garmin® - Gps- Portable Friction Mount - Nuvi & StreetPilot Mount 010-10908-00Garmin® - Gps- Portable Friction Mount - Nuvi & StreetPilot Mount 010-10908-00 $19.97
New ListingApple iPhone 15 - 128 Gb - Pink (T-Mobile) lockedNew ListingApple iPhone 15 - 128 Gb - Pink (T-Mobile) locked $250.00 New ListingGoogle Pixel 4 64Gb, White, UnlockedNew ListingGoogle Pixel 4 64Gb, White, Unlocked $119.95
Garmin Marine Gps Electronics Logo Black Distressed Hat Baseball Cap Adult SizeGarmin Marine Gps Electronics Logo Black Distressed Hat Baseball Cap Adult Size $25.99 New Automatic Gps | Toyota Prius Yaris | Electronic power steering controllerNew Automatic Gps | Toyota Prius Yaris | Electronic power steering controller $99.99
New ListingApple iPhone 13 - 128Gb - Midnight (Unlocked)New ListingApple iPhone 13 - 128Gb - Midnight (Unlocked) $349.99 Cobra Electronics Cdr 840-Cd Hd Dash Cam Camera w/Gps Camera & 8Gb Micro Sd CardCobra Electronics Cdr 840-Cd Hd Dash Cam Camera w/Gps Camera & 8Gb Micro Sd Card $12.99
New ListingApple Iphone Xr Yellow 64Gb Unlocked Nice Battery Health 96%New ListingApple Iphone Xr Yellow 64Gb Unlocked Nice Battery Health 96% $159.99 SparkFun Electronics Gps-16344 Gps-Rtk Dead Reckoning Breakout Zed-F9R (Qwiic)SparkFun Electronics Gps-16344 Gps-Rtk Dead Reckoning Breakout Zed-F9R (Qwiic) $302.64
New ListingTcl 30Xl 64Gb T701Dl (Tracfone) Gray (E-0263)New ListingTcl 30Xl 64Gb T701Dl (Tracfone) Gray (E-0263) $77.95 Umidigi A15C 8Gb+128Gb 5000mAh Nfc Smartphone Android 13 Unlocked Very GoodUmidigi A15C 8Gb+128Gb 5000mAh Nfc Smartphone Android 13 Unlocked Very Good $125.82 to
New ListingApple iPhone 6s - 32 Gb - Space Gray (Unlocked) 93% Battery HealthNew ListingApple iPhone 6s - 32 Gb - Space Gray (Unlocked) 93% Battery Health $34.97 New ListingOnePlus 6T - Dual Sim - Black - 128Gb -A6010 (Unlocked) Lifted BackNew ListingOnePlus 6T - Dual Sim - Black - 128Gb -A6010 (Unlocked) Lifted Back $59.95
ElectronicsElectronics $375.99 New ListingDefective - Samsung Galaxy S20 5G - 128Gb - Gray - Gsm Unlocked - 5605New ListingDefective - Samsung Galaxy S20 5G - 128Gb - Gray - Gsm Unlocked - 5605 $119.99
Ram Composite Mount for Fishfinder Marine Electronics Gps BracketsRam Composite Mount for Fishfinder Marine Electronics Gps Brackets $24.09 New ListingGoogle Pixel 4a - 128 Gb - Black (Unlocked) Used Great Condition!New ListingGoogle Pixel 4a - 128 Gb - Black (Unlocked) Used Great Condition! $80.00
09-15 7 Series Gps Navigation Electronic Audio Media Control Switch Factory Oem09-15 7 Series Gps Navigation Electronic Audio Media Control Switch Factory Oem $210.41 New ListingiPhone 12 64 Gb T-MobileNew ListingiPhone 12 64 Gb T-Mobile $199.00
New ListingApple iPhone 11 Pro - 256 Gb - Gray (Unlocked) (Single Sim)New ListingApple iPhone 11 Pro - 256 Gb - Gray (Unlocked) (Single Sim) $240.00 New ListingLot Of 10 Samsung Galaxy S5 S6 S7 Phones And 1 Motorola Phone Mix ConditionNew ListingLot Of 10 Samsung Galaxy S5 S6 S7 Phones And 1 Motorola Phone Mix Condition $350.00
Garmin Marine Gps Electronics Logo Embroidered Snapback Cap Black Hat Adult SizeGarmin Marine Gps Electronics Logo Embroidered Snapback Cap Black Hat Adult Size $15.95 International EleCtronics Nmea Buffer Zh 17 Gps MultiplexerInternational EleCtronics Nmea Buffer Zh 17 Gps Multiplexer $287.00
Bushnell Gps Ion Edge Golf Watch 36,000+ Courses loaded, Bluetooth, 15hr BatteryBushnell Gps Ion Edge Golf Watch 36,000+ Courses loaded, Bluetooth, 15hr Battery $149.99 Dragy Gps Performance Box Drg70 - V2 Updated HardwareDragy Gps Performance Box Drg70 - V2 Updated Hardware $159.00
New ListingNew Samsung Galaxy Note20 Ultra 5G In Mystic White Sealed In The BoxNew ListingNew Samsung Galaxy Note20 Ultra 5G In Mystic White Sealed In The Box $349.99 Dual Xgps160 SkyPro Bluetooth Gps Receiver for Mobile Devices with GlonassDual Xgps160 SkyPro Bluetooth Gps Receiver for Mobile Devices with Glonass $164.99
New ListingApple iPhone Xr A1984 6.1" 64Gb Black At&T!New ListingApple iPhone Xr A1984 6.1" 64Gb Black At&T! $40.00 Garmin Marq Adventurer Gps Sport Watch for Rugged Exploration 010-02006-26Garmin Marq Adventurer Gps Sport Watch for Rugged Exploration 010-02006-26 $699.99
Garmin Gpsmap 65S Outdoor Gps with Compass and Altimeter 010-02451-10Garmin Gpsmap 65S Outdoor Gps with Compass and Altimeter 010-02451-10 $359.99 Veethree Electronics Gps Receiver Nmea0183Veethree Electronics Gps Receiver Nmea0183 $79.00
New ListingSamsung Galaxy A13 5G 64Gb Sm-S136Dl (Tracfone) Black (E-0288)New ListingSamsung Galaxy A13 5G 64Gb Sm-S136Dl (Tracfone) Black (E-0288) $32.95 Molle Compact Pouch Polyester Compass Gps Electronics Phone Hiking PouchesMolle Compact Pouch Polyester Compass Gps Electronics Phone Hiking Pouches $12.99
New ListingSamsung Galaxy A21 32Gb Sm-A215U (Unknown) Black (E-0202)New ListingSamsung Galaxy A21 32Gb Sm-A215U (Unknown) Black (E-0202) $64.95 Apple iPhone 13 A2482 128Gb Network Unlocked Very Good ConditionApple iPhone 13 A2482 128Gb Network Unlocked Very Good Condition $384.00
New ListingSamsung Galaxy A11 - Sm-A115U1 - 32Gb - Black (Factory Unlocked) Tested & WorksNew ListingSamsung Galaxy A11 - Sm-A115U1 - 32Gb - Black (Factory Unlocked) Tested & Works $44.95 Apple iPhone 13 Pro Max A2484 128Gb Network Unlocked Very GoodApple iPhone 13 Pro Max A2484 128Gb Network Unlocked Very Good $569.00
New ListingFair Kyocera DuraForce Pro 2 E6910 64Gb Black (Verizon Only) See Notes Free ShipNew ListingFair Kyocera DuraForce Pro 2 E6910 64Gb Black (Verizon Only) See Notes Free Ship $33.99 Usgi Military Electronics Nylon Carrying Padded Case Gps Radio Receiver Plgr-96Usgi Military Electronics Nylon Carrying Padded Case Gps Radio Receiver Plgr-96 $24.99
Dual Electronics Xgps150A Multipurpose Portable Universal Bluetooth Gps Recei.Dual Electronics Xgps150A Multipurpose Portable Universal Bluetooth Gps Recei. $98.74 New ListingApple iPhone 13 Pro - 128 Gb - Green (Unlocked) (Single Sim)New ListingApple iPhone 13 Pro - 128 Gb - Green (Unlocked) (Single Sim) $400.00
New ListingApple iPhone 12 - 64 Gb - Black- *For Parts Only*New ListingApple iPhone 12 - 64 Gb - Black- *For Parts Only* $100.00 Apple iPhone 14, 128Gb, Network Unlocked - Excellent ConditionApple iPhone 14, 128Gb, Network Unlocked - Excellent Condition $484.00
New ListingApple iPhone 13 Pro Max Spectrum - Bad Lcd - CrackedNew ListingApple iPhone 13 Pro Max Spectrum - Bad Lcd - Cracked $249.00 Apple iPhone 14 128Gb Network Unlocked Very Good ConditionApple iPhone 14 128Gb Network Unlocked Very Good Condition $454.00
Bushnell BackTrack Mini Gps NavigationBushnell BackTrack Mini Gps Navigation $62.50 New ListingGoogle Pixel 7 - 128 Gb - Black (Unlocked) (Dual Sim (Sim + eSim)New ListingGoogle Pixel 7 - 128 Gb - Black (Unlocked) (Dual Sim (Sim + eSim) $75.00
Electronic Tablet Device Holder Gps Mount for Polaris Rzr Xp 1000 Turbo 2019-23Electronic Tablet Device Holder Gps Mount for Polaris Rzr Xp 1000 Turbo 2019-23 $48.96 New ListingApple iPhone 7 - 32 Gb - Silver (Unlocked) (Single Sim)New ListingApple iPhone 7 - 32 Gb - Silver (Unlocked) (Single Sim) $49.95
New ListingOnePlus 6 - 8Gb 128Gb - Black (Unlocked) (Dual Sim) SmartphoneNew ListingOnePlus 6 - 8Gb 128Gb - Black (Unlocked) (Dual Sim) Smartphone $74.95 New ListingApple iPhone 11 - 128 Gb - Black (Unlocked)New ListingApple iPhone 11 - 128 Gb - Black (Unlocked) $100.00
New ListingDual Electronics Xgps150A Multipurpose Portable Universal Bluetooth Gps Recei.New ListingDual Electronics Xgps150A Multipurpose Portable Universal Bluetooth Gps Recei. $149.47 New ListingFactory Unlocked Apple iPhone 12 128Gb Purple Mjn23Ll/ANew ListingFactory Unlocked Apple iPhone 12 128Gb Purple Mjn23Ll/A $294.99
Samsung Galaxy S21 5G Unlocked G991U 128Gb Android Smartphone ExcellentSamsung Galaxy S21 5G Unlocked G991U 128Gb Android Smartphone Excellent $189.99 Ram Composite Mount for Fishfinder Marine Electronics Gps Gimbal BracketsRam Composite Mount for Fishfinder Marine Electronics Gps Gimbal Brackets $33.99
Click to see more GPS items at www.ebay.com
Prices current as of last update, 07/15/24 4:14pm.

Home Contact Resources Exchange Links ebay