Brief introduction of positioning system

According to the definition of school-enterprise alliance of Internet of Things in China, obtaining location information through location system is an important research topic in the Internet of Things era. The challenges to positioning technology in the Internet of Things environment are mainly reflected in: accurate positioning in heterogeneous networks and changeable environments; Large-scale application; Location-based services; Information security and privacy protection brought by location information. Date of launch: number of rocket flights: satellite number: satellite type: launch site: June 65438 +20001October: Beidou-1A Beidou-1 xichang satellite launch center: June 65438+February 265438 +0 Beidou-1B2000. 8+0c February 3, 2007 Beidou-1d April 4, 2007 04: 001,the first Beidou navigation satellite 3A (M 1) of the Long March, Beidou II April 2009 15, and the second Beidou navigation satellite of the Long March. Kloc-0/)20 10, June 7, 20 10 8 1 05: 30, Long March 3A 126, the fifth Beidou navigation satellite (I1) 20/Kloc-. 20101218 04: 20 Long March 3A 136 Seventh Beidou navigation satellite (I2) 201/April10 04: 47/. 20 1 1 ninth Beidou navigation satellite (I4) 20 1 1 tenth Beidou navigation satellite (i5) at 05: 07 on July 27th. 20 12 at 0: 00 on February 25th 1 1 Beidou navigation satellite 2065438+at 4: 50 on April 30th, 2002 12, 13 Beidou navigation system networking satellites ("one arrow Fifteen Beidou navigation system networking satellites ("one arrow and two satellites") 20 12 65438+23: 33 Long March III C 170 The 16th Beidou navigation satellite global positioning system (GPS) is a new generation of space satellite navigation and positioning system jointly developed by the US army, navy and air force in the 1970s. Its main purpose is to provide real-time, all-weather and global navigation services for land, sea and air for information collection and nuclear explosion monitoring satellite positioning.

Some military applications, such as surveillance and emergency communication, are an important part of America's strategy of dominating the world. After more than 20 years of research and experiments, it cost 30 billion dollars. By March 1994, 24 GPS satellite constellations with global coverage of 98% had been deployed. The GPS global positioning system consists of three parts: the space part-GPS constellation; Ground control part-ground monitoring system; User equipment part -GPS signal receiver.

GPS positioning technology has the advantages of high precision, high efficiency and low cost, which makes it widely used in strengthening and establishing various geodetic control networks, as well as highway engineering survey and deformation measurement of large structures. GPS Navigator Simply put, GPS Navigator is a kind of automobile driving assistant equipment that can help users accurately locate their current position, calculate their journey according to the established destination, and guide users to their destination through map display and voice prompts.

It includes two important components: one is Global Positioning System (GPS). It consists of three parts: space satellite, ground monitoring and user receiving. In space, there are 24 satellites forming a distribution network, which are distributed in six quasi-synchronous orbits with an inclination of 55 degrees and a distance of 20,000 kilometers from the ground, and each orbit has 4 satellites. GPS satellites orbit the earth once every 12 hour, so that signals from 7 ~ 9 satellites can be received at any place on the earth at the same time. There are 1 master control stations and 5 monitoring stations on the ground, which are responsible for satellite monitoring, telemetry, tracking and control. They are responsible for observing each satellite and providing observation data to the main control station. After receiving the data, the main control station calculates the precise position of each satellite at each moment and transmits it to the satellite through three injection stations, and the satellite transmits these data to the receiving terminal equipment of the user through radio waves.

Note: The system was originally developed jointly by the US Army, Navy and Air Force in 1970s. Its main purpose is to provide real-time, all-weather and global navigation services for land, sea and air for some military purposes such as intelligence gathering, nuclear explosion monitoring and emergency communication, which is an important deployment of the US strategy of dominating the world. After more than 20 years of research and experiments, the GPS system cost 30 billion dollars. It was not until 65438+1March 1994 that 24 GPS satellite constellations with global coverage of 98% were officially laid out.

The second is the car navigation system. Only GPS system is not enough. It can only receive the data sent by GPS satellites and calculate the user's three-dimensional position, direction, moving speed and time, but has no path calculation ability. In order to realize the route navigation function, the GPS receiver in the user's hand also needs a set of perfect vehicle navigation system including hardware equipment, electronic map and navigation software.

The hardware of GPS navigator includes chip, antenna, processor, memory, screen, keys, speakers and other components. However, as far as the current situation is concerned, there is not much difference in hardware between GPS car navigators on the market, and the main difference is concentrated on the built-in software and maps. What needs to be reminded here is that people are always concerned about what kind of maps are pre-installed in the navigator, which actually confuses the difference between maps and software. The so-called map is actually just data, and software is a search engine. How can the huge data of various geographic information in the map be applied by users? How is it reflected in the navigation interface? This will be achieved by software. Therefore, the navigation map can not be separated from the support of software. Conversely, even the best software system is useless without detailed map data.

To sum up, a complete GPS car navigator consists of chip, antenna, processor, memory, display screen, speaker, buttons, extended function slot, electronic map and navigation software 10.

To judge the quality of GPS navigator, the number of GPS satellites that the navigator can receive and the ability of path planning are the key. The more effective satellites the navigator can receive, the stronger its current signal and the more stable the navigation work. If a navigator often fails to search for satellites or frequently interrupts signals during navigation, which affects the normal navigation work, then the quality of the navigator is not enough, let alone good or bad.