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The author:(作者)qqpublished in(发表于) 2015/6/19 12:27:24 The big China “precision“ cm-level GPS challenge，
In recent days, domestic navigation companies unistrong has announced the first homemade satellite base enhanced services systems China "precision" official services and global synchronization publication, with China "accuracy", This means that China's Beidou case users do not need to set up the base station, you can enjoy at any location the high precision of centimeter-level service.
Unistrong said, China "accuracy" is China's first cover star of global operations base enhanced services systems, construction of the system presented at the end of 2013, has full independent intellectual property rights and full control over not only break the technological monopoly and blockade of international business, guarantee security and autonomy of national geo-spatial information, also covering the technology of satellite navigation industry in China.
And high precision of the Big Dipper before cell phones became available when the message is triggered by a large number of concerns, China "precision" also carried the full pride, pride and power of dreams, however, cm-level positioning is implemented? Its relevance, what does?
Why we are excited about the "cm positioning"?
Want to answer this question, you need to first "China precision" positioning principle based on the Beidou navigation system is a brief introduction and reference to the Big Dipper, naturally and ultimately do with Pioneer GPS navigation and positioning technology.
First for said GPS of positioning principle, GPS system main by three part composition, respectively is space constellation (21 star work satellite and 3 star alternate satellite), and ground monitoring system and Terminal (GPS received device)--24 star satellite uniform distribution in 6 a track plane Shang, then through will track surface set into specific angle, guarantee has global any locations, and time and received device are can received to 4 star satellite of signal.
It is worth mentioning that, birth of the GPS positioning system was designed as a one-way transmission, namely terminals only accept and send the signal, and this leads to the question, because satellites only broadcast their location, and GPS can receive satellite data, the user is in the process of being identified? Requires the use of terminal equipment at this point coming from the signals received from GPS satellites and uses information to calculate three dimensional position and time of the user. Calculation jobs rely on, is the GPS chip and atomic clocks. Central role of GPS chip is read information from satellites and related operations, and atomic clock is to ensure time accuracy.
Because satellites broadcast their own position, will attach information issued by the device after receiving the information, and then after the current time minus the time multiplied by the speed of light, finally arrive at the Terminal and the distance. And even the smallest errors need to be multiplied by the speed of light, the end result will be poor far, therefore, atomic clocks in the positioning system is extremely important.
Beidou navigation system and GPS are broadly similar, from each of three components of GPS space segment, ground segment and user segment is composed of three parts. Among them, the space segment of the Beidou navigation system (plan) consists of 35 satellites, including 5 geostationary orbit satellites, 27 Earth orbiting satellites and 3 inclined geosynchronous orbit satellites, Beidou 11 satellites than GPS, then there is for satellite distribution, project cycle and meet the "receive" function and other factors.
There need to be clear is that the first generation of location belongs to the source location of the Beidou navigation system, less reliable, and now the second generation Beidou navigation system is passive location using GPS-like technology. And the advantage of having a number of satellites, the words "source" and "short communication" is not available in GPS function, the Beidou navigation system in positioning signals, precision and ease of use there are certain advantages, it is also the main reason that it can quickly catch up with GPS.
Having finished the explanation of principles of navigation, it's easy to understand, centimeter-level position is actually the embodiment of a breakthrough on the positioning accuracy, and higher positioning accuracy, it can apply to wider areas, greater practical value.
Centimeter-level positioning is how to achieve it?
From a technical point of view, the Beidou system was able to make the progress from meters to centimeters, "ground enhancement network" this system plays a key role.
The so-called "ground enhancement network" system, which is compatible with compass, GPS, GLONASS and other navigation system integrated service systems, benchmark consists of a series of ground satellite stations, received and processed by mobile communications, digital broadcasting, satellite and other means of advertisement and the corresponding terminals to improve positioning accuracy.
And many people may not be able to understand the concept of centimeter-level positioning is what? For example, when we look at Hollywood, see plane projection accurate shot shells into a room in the building, or even a chimney of the factory holes, rely on is cm-level even more accurate positioning technology to achieve.
And except war and defense field zhiwai, including fine agricultural, and disaster monitoring, and land water, and intelligent grid, and mobile communications, aspects, cm level positioning technology also promising, like wisdom city in the of key link--traffic, in has has cm level technology zhihou, on can in map Shang completely displayed actual walking route, on focus operation vehicles, and engineering vehicles, and big truck, and school car, for precise monitoring, on illegal overtaking, behavior for real-time intelligent of regulatory and so on.
For example, positioning technologies and information and weather after the link up, environmental protection, urban construction, when a building settlement or deformation, Beidou system can quickly detect sensor shift and change, automatic alarm, similar programme can also be used for emergency medical and other fields.
Cm-level position is not enough, the big challenge GPS and resistance road long
However, although after centimeter-level positioning in the implementation of the Big Dipper, in precision of GPS have gaps, but that does not mean that the former has challenged the latter's capital. First of all, centimeter position referred to above is the main way to rely on "ground enhancement network" to achieve, but site selection and construction of ground reference stations is limited, not how fast or how widespread coverage, and as a result, compared to the accuracy of the compass system for GPS, the actual benefits are limited.
And, Beidou system of started time too late, currently city accounted for rate only in 1% around, even has two-way communications of unique technology advantage and better of price, but wants to corners overtaking is hard, because technology Shang of behind is to beyond of, like above mentioned of GPS chip, earlier on has statistics pointed out that China satellite navigation chip market up to 95% of has was United States GPS chip occupation, Most domestic enterprises do not have the capacity to develop such multiple-mode navigation chip had become a major bottleneck in industrialization of Beidou satellite navigation applications, if you do not solve the problem, our navigation chip industry will continue to linger in the low value-added products, achieving compass and GPS navigation replaced United States planning for GPS navigation is also struggling – and that is the later of the helpless.
But conversely, Beidou system start time is short so far, far less than the GPS more than 20 years, but compared to Russia's Glonass and Europe's Galileo, compass system is still not small. More importantly, it is our own control, which means that in this area, China has no fear of United States monopoly – you know, United States at the time of the Gulf war put its European allies in the lurch and forced closure of GPS Service to Europe, and in modern warfare, if the loss of mastery of the positioning system, then it's basically meant to be trampled upon.
Sun Tzu said: the soldiers, an important affair of State, life and death, survival of the road, is overthrown.
That's why said "China precision" led a series of engineering and construction projects, both business needs and industry demand, but is due to national requirements.
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