What is the difference between Beidou navigation system and GPS
I believe most people know GPS, but some people may not know much about Beidou navigation system, this domestic navigation system , today we will talk about the difference between the two.
1. Coverage: Beidou Navigation System is a regional navigation system covering the territory of my country. The coverage is about 70??-140?? east longitude and 5??-55?? north latitude. GPS is an all-weather navigation system with global coverage. It can ensure that 6-9 satellites can be observed at any time and anywhere on the earth at the same time (actually, up to 11 satellites can be observed).
2. Number of satellites and orbit characteristics: Beidou Navigation System is to set 2 geostationary satellites on the earth’s equatorial plane with an equatorial angular distance of about 60??. GPS is to set 24 satellites on 6 orbital planes, the orbital equatorial inclination is 55??, and the orbital plane equatorial angle is 60??. Aviation satellites are in quasi-synchronous orbit, orbiting the earth in 11 hours and 58 minutes.
3. Positioning principle: Beidou navigation system is an active two-way ranging two-dimensional navigation. It is calculated by the ground center control system and provides users with three-dimensional positioning data. GPS is passive pseudo-code one-way ranging three-dimensional navigation. The user equipment independently solves its own 3D positioning data. This working principle of ‘Beidou-1’ brings two problems. One is that the radio concealment is lost while the user is positioning, which is quite unfavorable in the military. , at a disadvantage in terms of 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 25-100m to 12m, and the timing accuracy is about 20ns.
5. User capacity: Because the Beidou navigation system is an active two-way ranging inquiry-response system, the user equipment and the geostationary satellite must not only receive the inquiry signal of the ground central control system, but also require the user The equipment transmits the reply signal to the geostationary satellite, in this way, the user capacity of the system depends on the channel blocking rate allowed by the user, the rate of the inquiry signal and the user’s response frequency. Therefore, the user equipment capacity of Beidou navigation system is limited. GPS is a one-way ranging system. The user equipment can perform ranging and positioning as long as it receives the navigation message sent by the navigation satellite. Therefore, the capacity of the 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’ is obviously more dependent on the central control system A lot, because the location solving is done there and not by the user device. In order to make up for the vulnerability of this system, GPS is developing interstellar horizontal data link technology, so that the GPS satellites can operate independently if the main control station is destroyed. The ‘Beidou No. 1’ system has ruled out this possibility in principle. Once the central control system is damaged, the system cannot continue to work.
7. Real-time: The positioning application of ‘Beidou No. 1’ users 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 which time passes through geostationary satellites. Going back and forth, plus satellite forwarding and processing by the central control system, the time delay will be longer, so for high-speed moving objects, the positioning error will be increased. In addition, the ‘Beidou No. 1’ satellite navigation system also has some characteristics of its own, and the SMS communication function it has is not available in GPS.