Global Navigation Satellite System (GNSS) is the standard generic term for satellite navigation systems that provide autonomous geo-spatial positioning with global coverage. A GNSS allows small electronic receivers to determine their location (longitude, latitude, and altitude) to within a few metres using time signals transmitted along a line of sight by radio from satellites. Receivers on the ground with a fixed position can also be used to calculate the precise time as a reference for scientific experiments. GLONASS GLONASS (Russian ГЛОНАСС; ГЛОбальная НАвигационная Спутниковая Система; Globalnaya Navigatsionnaya Sputnikovaya Sistema. ... Surface mount electronic components Electronics is the study of the flow of charge through various materials and devices such as semiconductors, resistors, inductors, capacitors, nano-structures and vacuum tubes. ... Longitude is the east-west geographic coordinate measurement most commonly utilized in cartography and global navigation. ... This article is about the geographical term. ... Altitude is the elevation of an object from a known level or datum. ... This article is about the unit of length. ... A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day. ... When viewing a scene, as in optics, photography, or even hunting, the line of sight is the straight line between the observer and the target. ... This article is about artificial satellites. ...

As of 2007, the United States NAVSTAR Global Positioning System (GPS) is the only fully operational GNSS. The Russian GLONASS is a GNSS in the process of being restored to full operation. The European Union's Galileo positioning system is a next generation GNSS in the initial deployment phase, scheduled to be operational in 2013. China has indicated it may expand its regional Beidou navigation system into a global system. India's IRNSS, a next generation GNSS is in developmental phase and is scheduled to be operational around 2012. 2007 is a common year starting on Monday of the Gregorian calendar. ... GPS redirects here. ... GLONASS GLONASS (Russian ГЛОНАСС; ГЛОбальная НАвигационная Спутниковая Система; Globalnaya Navigatsionnaya Sputnikovaya Sistema. ... The Galileo positioning system is a planned Global Navigation Satellite System, to be built by the European Union (EU) and European Space Agency (ESA). ... The Beidou navigation system is a project by the Peoples Republic of China to develop an independent satellite navigation system. ... The Indian Regional Navigational Satellite System (IRNSS) is a proposed autonomous regional satellite navigation system to be constructed and controlled by the Indian government. ...

GNSS classification

GNSS that provide enhanced accuracy and integrity monitoring usable for civil navigation are classified as follows:^[1]

• GNSS-1 is the first generation system and is the combination of existing satellite navigation systems (GPS and GLONASS), with Satellite Based Augmentation Systems (SBAS) or Ground Based Augmentation Systems (GBAS). In the United States, the satellite based component is the Wide Area Augmentation System (WAAS), in Europe it is the European Geostationary Navigation Overlay Service (EGNOS), and in Japan it is the Multi-Functional Satellite Augmentation System (MSAS). Ground based augmentation is provided by systems like the Local Area Augmentation System (LAAS).

• GNSS-2 is the second generation of systems that independently provides a full civilian satellite navigation system, exemplified by the European Galileo positioning system. These systems will provide the accuracy and integrity monitoring necessary for civil navigation. This system consists of L1 and L2 frequencies for civil use and L5 for system integrity. Development is also in progress to provide GPS with civil use L2 and L5 frequencies, making it a GNSS-2 system.¹

• Core Satellite navigation systems, currently GPS, Galileo and GLONASS.
• Global Satellite Based Augmentation Systems (SBAS) such as Omnistar and StarFire.
• Regional SBAS including WAAS(US), EGNOS (EU), MSAS (Japan) and GAGAN (India).
• Regional Satellite Navigation Systems such a QZSS (Japan), IRNSS (India) and Beidou (China).
• Continental scale Ground Based Augmentation Systems (GBAS) for example the Australian GRAS and the US Department of Transportation National Differential GPS (DGPS) service.
• Regional scale GBAS such as CORS networks.
• Local GBAS typified by a single GPS reference station operating Real Time Kinematic (RTK) corrections.

Augmentation of a Global Navigation Satellite System (GNSS) is a method of improving system attributes such as accuracy, reliability, and availability through the integrated of external information into the calculation process. ... Augmentation of a Global Navigation Satellite System (GNSS) is a method of improving system attributes such as accuracy, reliability, and availability through the integrated of external information into the calculation process. ... WAAS System Overview The Wide Area Augmentation System (WAAS) is an extremely accurate navigation system developed for civil aviation by the Federal Aviation Administration (FAA), a division of the United States Department of Transportation (DOT). ... The European Geostationary Navigation Overlay Service (EGNOS) is a satellite navigation system under development by the European Space Agency, the European Commission and EUROCONTROL. It is intended to supplement the GPS and GLONASS systems by reporting on the reliability and accuracy of the signals. ... MTSAT are a series of weather and aviation control satellites. ... LAAS Architecture The Local Area Augmentation System (LAAS) is an all-weather landing system based on real-time differential correction of the GPS signal. ... GPS redirects here. ... StarFire is a wide-area Differential GPS system developed by John Deeres NavCom and Precision Farming groups. ... Differential Global Positioning System (DGPS) is an enhancement to Global Positioning System that uses a network of fixed ground based reference stations to broadcast the difference between the positions indicated by the satellite systems and the known fixed positions. ... Real Time Kinematic (RTK) land survey is based on a differential use of carrier phase measurements of the GPS, Glonass and/or Galileo signals where a single reference station provides the real-time corrections of even to a centimetre level of accuracy. ...

History and theory

Early predecessors were the ground based DECCA, LORAN and Omega systems, which used terrestrial longwave radio transmitters instead of satellites. These systems broadcast a radio pulse from a known "master" location, followed by repeated pulses from a number of "slave" stations. The delay between the reception and sending of the signal at the slaves was carefully controlled, allowing the receivers to compare the delay between reception and the delay between sending. From this the distance to each of the slaves could be determined, providing a fix. Decca Navigator Mk 12 The Decca Navigator System was a hyperbolic low frequency radio navigation system (also known as multilateration) that was first deployed during World War II when the Allied forces needed a system which could be used to achieve accurate landings. ... LORAN (LOng RAnge Navigation) is a terrestrial navigation system using low frequency radio transmitters that use the time interval between radio signals received from three or more stations to determine the position of a ship or aircraft. ... Omega is the name for the first truly global radionavigation system for aircraft operated by the United States of America in cooperation with six partner nations. ... This article does not cite any references or sources. ... In communications and information processing, a transmitter (sometimes abbreviated XMTR) is an object (source) which sends information to an observer (receiver). ... A position fix or simply a fix is a term used in position fixing in navigation to describe a position derived from measuring external reference points. ...

The first satellite navigation system was Transit, a system deployed by the US military in the 1960s. Transit's operation was based on the Doppler effect: the satellites traveled on well-known paths and broadcast their signals on a well known frequency. The received frequency will differ slightly from the broadcast frequency because of the movement of the satellite with respect to the receiver. By monitoring this frequency shift over a short time interval, the receiver can determine its location to one side or the other of the satellite, and several such measurements combined with a precise knowledge of the satellite's orbit can fix a particular position. Operational Transit satellite The TRANSIT system, also known as NAVSAT (for Navy Navigation Satellite System), was the first satellite navigation system to be used operationally. ... A source of waves moving to the left. ... For other uses, see Frequency (disambiguation). ...

Part of an orbiting satellite's broadcast included its precise orbital data. In order to ensure accuracy, the US Naval Observatory (USNO) continuously observed precisely the orbits of these satellites. As a satellite's orbit deviated, the USNO would send the updated information to the satellite. Subsequent broadcasts from an updated satellite would contain the most recent accurate information about its orbit. Aerial view of USNO. The United States Naval Observatory (USNO) is one of the oldest scientific agencies in the United States. ...

Modern systems are more direct. The satellite broadcasts a signal that contains the position of the satellite and the precise time the signal was transmitted. The position of the satellite is transmitted in a data message that is superimposed on a code that serves as a timing reference. The satellite uses an atomic clock to maintain synchronization of all the satellites in the constellation. The receiver compares the time of broadcast encoded in the transmission with the time of reception measured by an internal clock, thereby measuring the time-of-flight to the satellite. Several such measurements can be made at the same time to different satellites, allowing a continual fix to be generated in real time. “Nuclear Clock” redirects here. ...

Each distance measurement, regardless of the system being used, places the receiver on a spherical shell at the measured distance from the broadcaster. By taking several such measurements and then looking for a point where they meet, a fix is generated. However, in the case of fast-moving receivers, the position of the signal moves as signals are received from several satellites. In addition, the radio signals slow slightly as they pass through the ionosphere, and this slowing varies with the receiver's angle to the satellite, because that changes the distance through the ionosphere. The basic computation thus attempts to find the shortest directed line tangent to four oblate spherical shells centered on four satellites. Satellite navigation receivers reduce errors by using combinations of signals from multiple satellites and multiple correlators, and then using techniques such as Kalman filtering to combine the noisy, partial, and constantly changing data into a single estimate for position, time, and velocity. The Kalman filter is an efficient recursive filter that estimates the state of a dynamic system from a series of incomplete and noisy measurements. ...

Civil and military uses

Main article: GNSS applications

The original motivation for satellite navigation was for military applications. Satellite navigation allows for hitherto impossible precision in the delivery of weapons to targets, greatly increasing their lethality whilst reducing inadvertent casualties from mis-directed weapons. (See smart bomb). Satellite navigation also allows forces to be directed and to locate themselves more easily, reducing the fog of war. A Global Navigation Satellite System (GNSS) receiver, which may use the GPS, GLONASS, or Beidou system, is capable of being used in many applications. ... BOLT-117 laser guided bomb Precision-guided munitions (smart munitions or smart bombs) are self-guiding weapons intended to maximize damage to the target while minimizing collateral damage. Because the damage effects of an explosive weapon scale as a power law with distance, quite modest improvements in accuracy (and hence... The fog of war is a term used to describe the level of ambiguity in situational awareness experienced by participants in military operations. ...

Satellite navigation using a laptop and a GPS receiver

In these ways, satellite navigation can be regarded as a force multiplier. In particular, the ability to reduce unintended casualties has particular advantages for wars where public relations is an important aspect of warfare. For these reasons, a satellite navigation system is an essential asset for any aspiring military power. Satellite navigation. ... Satellite navigation. ... An ultraportable IBM X31 with 12 screen on an IBM T43 Thin & Light laptop with a 14 screen HCLs $329 miniature notebooks with 6 TFT touchscreens launched in India on January 29, 2008. ... Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ... A force multiplier is a military term referring to a factor that dramatically increases (hence multiplies) the combat effectiveness of a military force. ...

GNSS systems have a wide variety of uses:

• Navigation, ranging from personal hand-held devices for trekking, to devices fitted to cars, trucks, ships and aircraft
• Time transfer and synchronization
• Location-based services such as enhanced 911
• Surveying
• Entering data into a geographic information system
• Search and rescue
• Geophysical Sciences
• Tracking devices used in wildlife management

Note that the ability to supply satellite navigation signals is also the ability to deny their availability. The operator of a satellite navigation system potentially has the ability to degrade or eliminate satellite navigation services over any territory it desires. This article is about determination of position and direction on or above the surface of the earth. ... Time transfer describes methods for transferring reference clock synchronization from one point to another, often over long distances. ... Synchronization (or Sync) is a problem in timekeeping which requires the coordination of events to operate a system in unison. ... Location-based services (LBS) (or LoCation Services, LCS) are services developed and distributed by wireless carriers and their partners which provide information specific to a location. ... To meet Wikipedias quality standards and make it easier to understand, this article or section may require cleanup. ... Surveyor at work with a leveling instrument. ... GIS redirects here. ... Search and Rescue (acronym SAR) is an operation mounted by emergency services, often well-trained volunteers, to find someone believed to be in distress, lost, sick or injured either in a remote or difficult to access area, such as mountains, desert or forest (Wilderness search and rescue), or at sea...

Current global navigation systems

GPS

Main article: Global Positioning System

The United States' Global Positioning System (GPS), which as of 2007 is the only fully functional, fully available global navigation satellite system. It consists of up to 32 medium Earth orbit satellites in six different orbital planes, with the exact number of satellites varying as older satellites are retired and replaced. Operational since 1978 and globally available since 1994, GPS is currently the world's most utilized satellite navigation system.Currently it is widely used navigational system GPS redirects here. ... GPS redirects here. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... Intermediate circular orbit (ICO), also called medium earth orbit (MEO), is used by satellites between the altitudes of low earth orbit (up to 1400 km) and geostationary orbit (ca. ... The orbital plane is an astronomical concept. ...

GLONASS

Main article: GLONASS

The formerly Soviet, and now Russian, Global'naya Navigatsionnaya Sputnikovaya Sistema, or GLONASS, was a fully functional navigation constellation but since the collapse of the Soviet Union has fallen into disrepair, leading to gaps in coverage and only partial availability. The Russian Federation has pledged to restore it to full global availability by 2010 with the help of India, who is participating in the restoration project.^[2][3] GLONASS GLONASS (Russian ГЛОНАСС; ГЛОбальная НАвигационная Спутниковая Система; Globalnaya Navigatsionnaya Sputnikovaya Sistema. ... Soviet redirects here. ... GLONASS GLONASS (Russian ГЛОНАСС; ГЛОбальная НАвигационная Спутниковая Система; Globalnaya Navigatsionnaya Sputnikovaya Sistema. ...

Proposed global navigation systems

Compass

Main article: COMPASS navigation system

China has indicated they intend to expand their regional navigation system, called Beidou or Big Dipper, into a global navigation system; a program that has been called Compass in China's official news agency Xinhua. The Compass system is proposed to utilize 30 medium Earth orbit satellites and five geostationary satellites. Having announced they are willing to cooperate with other countries in Compass's creation, it is unclear how this proposed program impacts China's commitment to the international Galileo position system. The COMPASS system (also known as Beidou-2) is a project by China to develop an independent satellite navigation system. ... Front gate of the main building of Xinhua News Agency in Beijing For other uses, see Xinhua (disambiguation). ... Intermediate circular orbit (ICO), also called medium earth orbit (MEO), is used by satellites between the altitudes of low earth orbit (up to 1400 km) and geostationary orbit (ca. ...

DORIS

Main article: DORIS (geodesy)

Doppler Orbitography and Radio-positioning Integrated by Satellite (DORIS) is a French precision system.^[4] navigation system Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) is a french satellite system used for the determination of satellite orbis (e. ...

Galileo

Main article: Galileo (satellite navigation)

The European Union and European Space Agency agreed on March 2002 to introduce their own alternative to GPS, called the Galileo positioning system. At a cost of about GBP £2.4 billion,^[5] the system is scheduled to be working from 2012. The first experimental satellite was launched on 28 December 2005. Galileo is expected to be compatible with the modernized GPS system. The receivers will be able to combine the signals from both Galileo and GPS satellites to greatly increase the accuracy. ESA redirects here. ... The Galileo positioning system is a planned Global Navigation Satellite System, to be built by the European Union (EU) and European Space Agency (ESA). ... GBP redirects here. ... is the 362nd day of the year (363rd in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... The United States Global Positioning System (GPS), having reached Fully Operational Capability on July 17, 1995[1] completed its original design goals. ...

IRNSS

Main article: Indian Regional Navigational Satellite System

The Indian Regional Navigational Satellite System (IRNSS) is a proposed autonomous regional satellite navigation system to be constructed and controlled by the Indian government. It is intended to provide an absolute position accuracy of better than 20 meters throughout India and within a region extending approximately 1,500 to 2,000 km around it. A goal of complete Indian control has been stated, with the space segment, ground segment and user receivers all being built in India. The government approved the project in May 2006, with the intention it be implemented within six to seven years. The Indian Regional Navigational Satellite System (IRNSS) is a proposed autonomous regional satellite navigation system to be constructed and controlled by the Indian government. ... ...

QZSS

Main article: Quasi-Zenith Satellite System

The Quasi-Zenith Satellite System (QZSS), is a proposed three-satellite regional time transfer system and enhancement for GPS covering Japan. The first satellite is scheduled to be launched in 2008.^[6] There are very few or no other articles that link to this one. ... Time transfer describes methods for transferring reference clock synchronization from one point to another, often over long distances. ... GPS redirects here. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance with the Gregorian calendar. ...

GNSS Augmentation

Main article: GNSS Augmentation

GNSS Augmentation involves using external information, often integrated into the calculation process, to improve the accuracy, availability, or reliability of the satellite navigation signal. There are many such systems in place and they are generally named or described based on how the GNSS sensor receives the information. Some systems transmit additional information about sources of error (such as clock drift, ephemeris, or ionospheric delay), others provide direct measurements of how much the signal was off in the past, while a third group provide additional navigational or vehicle information to be integrated in the calculation process. Augmentation of a Global Navigation Satellite System (GNSS) or Blended navigation is a method of improving the navigation systems attributes, such as accuracy, reliability, and availability, through the integration of external information into the calculation process. ...

Examples of augmentation systems include the Wide Area Augmentation System, the European Geostationary Navigation Overlay Service, the Multi-functional Satellite Augmentation System, Differential GPS, and Inertial Navigation Systems. WAAS System Overview The Wide Area Augmentation System (WAAS) is an extremely accurate navigation system developed for civil aviation by the Federal Aviation Administration (FAA), a division of the United States Department of Transportation (DOT). ... The European Geostationary Navigation Overlay Service (EGNOS) is a satellite navigation system under development by the European Space Agency, the European Commission and EUROCONTROL. It is intended to supplement the GPS and GLONASS systems by reporting on the reliability and accuracy of the signals. ... Multi-functional Satellite Augmentation System (MSAS) is a Satellite Based Augmentation System, i. ... Differential Global Positioning System (DGPS) is an enhancement to Global Positioning System that uses a network of fixed ground based reference stations to broadcast the difference between the positions indicated by the satellite systems and the known fixed positions. ... An inertial navigation system measures the position and altitude of a vehicle by measuring the accelerations and rotations applied to the systems inertial frame. ...

Topics to be covered

• Differential satellite navigation
• GNSS reflectometry
• Phase-counting differential satellite navigation
• Trends within GNSS

GNSS reflectometry involves making measurements from the reflections from the Earth of navigation signals from Global Navigation Satellite Systems such as GPS. It is also known as GPS reflectometry. ... GNSS - Global Navigation Satellite System In 1994 in a meeting of the ECAC, a satellite strategy was approved, with as targets: - firstly developing items for an European supplement on the current satellite systems, now called GNSS-1 - secondly designing and defining future satellite systems for civil use (called GNSS-2...

See also

• Differential GPS
• Global Positioning System
• Galileo (satellite navigation)
• GLONASS
• Wide Area Augmentation System
• European Geostationary Navigation Overlay Service
• GNSS reflectometry
• GPS and Geo Augmented Navigation
• SIGI
• RAIM

Differential Global Positioning System (DGPS) is an enhancement to Global Positioning System that uses a network of fixed ground based reference stations to broadcast the difference between the positions indicated by the satellite systems and the known fixed positions. ... GPS redirects here. ... GLONASS GLONASS (Russian ГЛОНАСС; ГЛОбальная НАвигационная Спутниковая Система; Globalnaya Navigatsionnaya Sputnikovaya Sistema. ... WAAS System Overview The Wide Area Augmentation System (WAAS) is an extremely accurate navigation system developed for civil aviation by the Federal Aviation Administration (FAA), a division of the United States Department of Transportation (DOT). ... The European Geostationary Navigation Overlay Service (EGNOS) is a satellite navigation system under development by the European Space Agency, the European Commission and EUROCONTROL. It is intended to supplement the GPS and GLONASS systems by reporting on the reliability and accuracy of the signals. ... GNSS reflectometry involves making measurements from the reflections from the Earth of navigation signals from Global Navigation Satellite Systems such as GPS. It is also known as GPS reflectometry. ... The GPS Aided Geo Augmented Navigation or GPS and Geo Augmented Navigation system (GAGAN) is a planned implementation of a Satellite Based Augmentation System (SBAS) by the Indian government. ... In Norse Mythology, Sigi is a one of the sons of Odin. ... Raum the Old. ...

External links

Information on specific GNSS systems

• ESA information on EGNOS
• Information on the Beidou system
• German Federal Waterways Administration Traffic Technologies Centre Information on GPS / DGPS

Organizations related to GNSS

• United Nations International Committee on Global Navigation Satellite Systems (ICG)
• Korean GNSS Technology Council (GTC)
• Institute of Navigation (ION) GNSS Meetings
• The International GNSS Service (IGS), formerly the International GPS Service
• International Global Navigation Satellite Systems Society Inc (IGNSS)
• International Earth Rotation and Reference Systems Service (IERS) International GNSS Service (IGS)
• UNAVCO GNSS Modernization
• Asia-Pacific Economic Cooperation (APEC) GNSS Implementation Team
• Fédération Aéronautique Internationale (FAI) GNSS Flight Recorder Approval Committee (GFAC)

Supportative or illustrative sites

• GPS and GLONASS Simulation (Java_applet) Simulation and graphical depiction of the motion of space vehicles, including DOP computation.

A Java applet is an applet delivered in the form of Java bytecode. ... This article pertains to the Global Positioning System. ...

References

1. ^ http://www.ifatca.org/docs/gnss.pdf IFATCA - A Beginner’s Guide to GNSS in Europe
2. ^ India signs GLONASS agreement
3. ^ India, Russia Agree On Joint Development Of Future Glonas Navigation System
4. ^ DORIS information page
5. ^ BBC - Galileo
6. ^ Japan Seeking 13 Percent Budget Hike for Space Activities