Global Navigation Satellite System
GNSS or Global Navigation Satellite System, positioning using a satellite pseudoranges , ephemeris, satellite launch time outlook measurements to be, but you must also know the user clock error . GNSS is a space-based radionavigation and navigation system capable of providing users with all-weather 3D coordinates and velocity and time information anywhere on the Earth’s surface or in near-Earth space. Therefore, the popular point that if you want to know in addition to latitude and longitude also want to know the height, then, must receive four satellites in order to accurately locate. Heathrow to Gatwick
Global Navigation Satellite System
Satellite navigation and positioning technology has basically replaced the ground-based radio navigation, the traditional geodesy and astronomical navigation and positioning technology, and to promote the geodesy and navigation and positioning of the new field of development. Today, the GNSS system is not only the national security and economic infrastructure, but also reflects an important symbol of modern great power status and the country’s comprehensive national strength. Because of its political, economic, military and other aspects of great significance, the world’s major military powers and economies are competing to develop an independent satellite navigation system. April 14, 2007, China successfully launched the first Beidou satellite, marking the world’s fourth GNSS system into a substantive operational phase, estimated that by 2020 the United States GPS, Russia GLANESS, the EU GALILEO and China Compass Navigation systems and other four GNSS systems will be completed or completed modernization. In addition to these four major global system, including the regional system and enhance system in which regional system Japan’s QZSS and India IRNSS, enhance system are the United States WASS , Japan MSAS , the EU’s EGNOS , Indian GAGAN and Niger Niger NIG-GOMSAT-1 and the like. The next few years, satellite navigation systems will enter a new stage. Users will face four major global systems nearly 100 satellite navigation satellite coexistence and mutual compatibility of the situation. Rich navigation information can improve the usability, accuracy, completeness and reliability of satellite navigation users, but at the same time have to face the frequency resource competition, satellite navigation market competition, time and frequency competition and compatibility and interoperability disputes many problems. Hyperopia Definition
Global Navigation Satellite System
GPS is in the United States naval navigation satellite system developed on the basis of the radio navigation and positioning system. With the omnipotent, global, all-weather, continuous and real-time navigation, positioning and timing functions, can provide users with precise three-dimensional coordinates, speed and time. Today, there are 31 GPS satellites in orbit, including 10 GPS-2A satellites, 12 GPS-2R satellites, and 9 modernized GPS-2R-M and GPS-2F satellites with M-code signals. According to the GPS modernization plan, the United States in 2011 to promote the GPS replacement process.GPS-2F satellite is the second generation of GPS to the third generation of GPS transition of the last model, will further enable GPS to provide a higher positioning accuracy. Plecffy
With the level of technology advances, wireless communication technology and the Global Positioning System (GPS) technology is increasingly used in all aspects of daily life begins. Wireless communication (GSM) and DGPS play an important role in all aspects of security monitoring and maintenance. GSM-based wireless communication network coveringa wide range of data has been destroyed, the good lunch, and low cost. Separate GPS systems , vehicles and personnel to complete the GSM system to monitor vehicle and personnel location information sent by mobile phone users wireless positioning satellite communication links.
GLONASS is the second generation of military satellite navigation system independently developed and controlled by the former Soviet Union Ministry of Defense. This system is the second global satellite navigation system after GPS. GLONASS system consists of satellites, ground control station and user equipment, three parts, the system consists of 21 stars and three backup stars, composed of three orbital plane, each orbital surface has eight satellites, the track height of 10,000 9000 Km, the operating cycle of 11 hours and 15 minutes. GLONASS system in the 20th century, 70 years began to develop, in 1984 launched the first satellite orbit. However, due to lack of space funding, the system part of the satellite was aging, the most serious had only six satellites in December 2003, by the Russian Applied Mechanics Research and Production Corporation developed a new generation of satellites delivered to the Federal Space Agency and the Department of Defense trial, Preparing Glonass for a comprehensive 2008 update. On the technical side, anti-interference ability GLONASS system better than GPS, but the single point positioning accuracy of less than the GPS system . In 2004, India and Russia signed the “long-term cooperation agreement on the peaceful use of Russian GNSS”, formally joined the GLONASS system, plans to jointly launch 18 navigation satellites. The project began operation in 1976, 1995, the entire system is built and running. With the disintegration of the Soviet Union, GLONASS system is also unsustainable, to April 2002, the system only eight satellites can run. Since August 2001, Russia began to plan to resume and GLONASS modernization after the economic recovery GLONASS navigation constellation after 10 years of paralysis after the end of 2011, the end of the system-wide operation.On December 25, Russia with proton -K rocket launched three GLONASS-M satellites make satellite system GLONASS number reached 17.
The Galileo Satellite Navigation System (GALILEO) is a global satellite navigation and positioning system developed and built by the European Union. The program was published by the European Commission in February 1992 and is co-located with ESA. The system consists of 30 satellites, of which 27 stars, three backup stars. Satellite orbit height of 23616km, located in the three inclination of 56 ° orbital plane. In October 2012, the Galileo Global Satellite Navigation System, the second batch of two satellites successfully launched into space, the space has four formal Galileo satellites, can form a network, the initial realization of the ground precise positioning function GALILEO system is the world’s first A civilian-based global navigation satellite positioning system, put into operation, the global users will use multi-standard receiver, get more navigation and positioning of satellite signals, which will greatly improve the navigation positioning accuracy.
Compass satellite navigation system (BDS)
Compass satellite navigation system (BDS) is China’s independent research and development, independent operation of the global satellite navigation system. The system is divided into two generations, namely the Beidou generation and the Beidou second generation system. China’s last century 80’s decision to build the Big Dipper system, in 2003, Beidou satellite navigation verification system built. The system consists of four geosynchronous orbit satellites, the ground control part and the user terminal three parts.
Factors Affecting Global Navigation Satellite Positioning Accuracy
GPS there are three parts of the error:
The first part is all GPS receivers have, such as satellite clock error, ephemeris error, ionospheric error, troposphericerrors, etc., the error can be completely eliminated using differential technology;
The second part is the propagation delay error, the error can be largely eliminated, mainly depends on the distance between the reference receiver and the user receiver;
The third part is the error inherent in all GPS receivers, such as channel delay, multi-path effects , internal noise, the error can not be eliminated