Comparison between the most popular Beidou navigat

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Comparison between Beidou navigation system and GPS system

1. Coverage: Beidou navigation system is a regional navigation system covering China. The coverage is about 70 ° to 140 ° east longitude and 5 ° to 55 ° north latitude. GPS is an all-weather navigation system covering the whole world. It can ensure that satellites can be observed at any place and at any time on the earth (in fact, up to 11 satellites can be observed)

2. Number of satellites and orbital characteristics: the Beidou navigation system sets two geosynchronous satellites on the equatorial plane of the earth, with an equatorial angular distance of about 60 °. GPS sets 24 satellites on 6 orbital planes, with an equatorial inclination of 55 ° and an equatorial angle of 60 °. The aeronautical satellite is in a quasi synchronous orbit, orbiting the earth for 11 hours and 58 minutes

3. Positioning principle: Beidou navigation system is an active two-way ranging two-dimensional navigation. The ground center control system is used to solve the three-dimensional positioning data for users. GPS is a passive pseudo-random code one-way ranging three-dimensional navigation. The user equipment solves its own three-dimensional positioning data independently. The working principle of "Beidou-1" brings two problems. One is that the user location loses radio concealment at the same time, which is quite disadvantageous in military affairs. On the other hand, because the equipment must include a transmitter, it is disadvantageous in volume, weight, price and power consumption

4. Positioning accuracy: the three-dimensional positioning accuracy of Beidou navigation system is about tens of meters, and the timing accuracy is about 100ns. GPS three-dimensional positioning accuracy P code has been increased from 16m to 6m, c/a code has been increased from m to 12M, and the timing accuracy is about 20ns a few days ago

5. User capacity: as the Beidou navigation system is an active two-way ranging interrogation response system, the user equipment and the geosynchronous satellite not only receive the interrogation signal of the ground central control system, but also require the user equipment to transmit the response signal to the geosynchronous satellite. In this way, the user capacity of the system depends on the channel blocking rate allowed by the user, but attention should be paid to the interrogation signal rate and the user's response frequency. Therefore, the user equipment capacity of Beidou navigation system is limited. GPS is a one-way ranging system. As long as the user equipment receives the navigation message sent by the navigation satellite, it can carry out ranging and positioning. Therefore, the capacity of GPS user equipment is unlimited

6. Survivability: like all navigation and positioning satellite systems, "Beidou-1" is based on the work of the central control system and satellites, but "Beidou-1" obviously depends much more on the central control system, because the positioning solution is there rather than by user equipment. In order to make up for the vulnerability of this system. 6. It is not allowed to disassemble integrated circuits and printed boards with electricity. GPS is developing the interstellar horizontal data link technology, so that GPS satellites can operate independently in case of the destruction of the master control station. The "Beidou-1" system eliminates this possibility in principle. Once the central control system is damaged, the system cannot continue to work

7. Real time: the positioning application of the "Beidou-1" user should be sent back to the central control system. The central control system calculates the user's three-dimensional position data and then sends it back to the user. During this period, it needs to go back and forth through the geostationary satellite. With the satellite forwarding, the processing time delay of the central control system is longer. Therefore, for high-speed moving bodies, the positioning error is increased. In addition, the "Beidou-1" satellite navigation system also has some own characteristics,

1 "Beidou" has dual functions of positioning and communication, and its short message communication function is not available in GPS

2. "Beidou" positioning accuracy is 1.2m

3 The terminal price of "Beidou" is about 20000 yuan

4 The receiving terminal does not need to be laid. According to its conversion principle, it is divided into 2-ary slope method, integration method, parallel comparison method, voltage 1 frequency conversion method and successive comparison method, and other ground base stations

5 Ships in the disaster center can send messages in one second

although GPS has been widely used, it is by no means perfect

1. Its scale and cost are too large for other countries to follow. The space agencies of Russia and Europe are typical examples

2. GPS can only be used as navigation, but it can't realize communication function, so it can't meet the growing needs of users. If you only rely on GPS, it is easy to be controlled by others. "?? The application business of satellite positioning system in this field has just begun. Before that, some civil pilot projects have been carried out for more than a year.

when GPS in the United States was just used, it was much more expensive than "Beidou-1". In the early 1980s and early 1990s, when people were using GPS system, the cheapest GPS receiver cost tens of thousands of dollars, hundreds of thousands of dollars, two sets. The price of Beidou's current user terminal is higher than that of the low-end GPS. Now the price of GPS navigation system is generally several thousand yuan, and the price of high-precision GPS ranges from tens of thousands to hundreds of thousands of yuan. At present, the user terminal of Beidou is about 20000 yuan

another problem is that its uses and characteristics are different. GPS solves the problem of where I am located, such as in the desert and on the sea. Beidou not only solves the problem of where I am, it also solves the problem of where you are here. The user terminal of Beidou actually has the function of sending and receiving, while GPS only has the function of receiving. It knows the location through receiving, while Beidou has the function of sending and receiving. Its positioning needs to be transmitted and then get the location. At the same time, its location may be transmitted to you or to people who care about you, In fact, Beidou is a device with dual functions of positioning and communication. It is different in user groups and reception occasions

ps: when Beidou demonstrated that year, a researcher from the Institute of Seismology of the State Seismological Bureau issued a demonstration report on this issue. Beidou system will become a lifeline project, that is, some projects related to human survival activities. For example, after a major earthquake, all our wired systems may lose their functions, while Beidou system, as a satellite monitoring system, can have timely location reports, It can also communicate, such as the tsunami, which is actually caused by the earthquake. Beidou is right or wrong to go to the rescue. There are oscilloscope tube type flash detectors in front of and behind the display, storage oscilloscope tube type flash detectors and so on, which are often useful. It can send the location and relevant information related to the location in time, and we can send the information to the relevant departments. In fact, the price is related to the number of users. Compared with 10000 or 100000 users, the cost of user terminals will be very different. Now the main cost is in the user terminals. Beidou user terminals just said that there are both revenue and revenue. With the development of user business, the cost will surely fall. Therefore, "Beidou" is the potential of the civilian "Beidou 1". It is mainly in the integrated field of positioning and communication. The fields that need this integrated function will be fully applied. Now there are only customers who need positioning, and the need for Beidou is not urgent. However, for users who need both location and position transmission, Beidou satellite navigation and positioning system is very useful

the positioning accuracy of Beidou is equivalent to that of GPS, which is generally about 1.2 meters. According to the regulations, at present, the Beidou navigation system is open for use in China

ps: the handset of Beidou double star positioning and navigation system has been distributed to the border grass-roots company and has been widely used. (end)

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