1. Cover

Beidou positioning system is a regional navigation system covering China. The coverage range passes about 70 ° 140 ° east, and 5 ° 55 ° north latitude. GPS is a global all -weather positioning system. It can ensure that 6-9 satellites can be observed at any place and time on the earth (in fact, at most 11).

2. Number of satellites and track characteristics

The Beidou positioning system is about 60 ° of setting two Earth synchronous satellite satellites on the earth equatorial plane. GPS is set up 24 satellites on the 6 rail planes. The orbital equatorial angle is 55 °, and the equatorial angle of the orbit surface is 60 °. The satellite is aimed at the same track, 11 hours and 58 minutes around the earth.

3. Positioning principle

Beidou positioning system is a active two -way ranging two -dimensional navigation. The ground center control system is solved for the user's three -dimensional positioning data. The GPS positioning system is a passive pseudo -code unilateral ranging three -dimensional navigation. User device independently solve its own three -dimensional positioning data. The working principle of "Beidou" brings two aspects of the problem. One is that the user positioning loses the hiddenness of radio while positioning. This is quite unfavorable in military. On the other hand, because the equipment must include the transmitter, it is The price and power consumption are in an unfavorable position.

4. Positioning accuracy

The three -dimensional positioning accuracy of the Beidou positioning system is about tens of meters, and the time accuracy is about 100ns. GPS 3D positioning accuracy P code currently increases from 16m to 6m, C/A code currently increases from 25-100m to 12m, and the time accuracy is about 20ns a few days ago.

5. User capacity

Because the Beidou Positioning System is a active two-way ranging inquiry-response system, the user equipment and the earth synchronous satellite must not only receive the inquiry signal of the ground center control system, but also require the user device to launch a signal of the synchronous satellite. The user capacity depends on the channel blockage rate of the user, inquiring the signal rate, and the user's response frequency. Therefore, the user equipment capacity of the Beidou positioning system is limited. GPS is a one -way ranging system. As long as the user device receives the navigation electrical text issued by the navigation satellite, the ranging positioning can be performed. Therefore, the user equipment capacity of the GPS positioning is unlimited.

6. Survival ability

Like all positioning satellite systems, the "Beidou" is based on the work of the central control system and satellite, but the "Beidou" on the central control system is significantly much larger, because the positioning solution is not done by the user's device. In order to make up for this systemic damage, GPS is developing interstellar horizontal data chain technology, so that the GPS satellite can operate independently after the main control station is destroyed. The "Beidou" system eliminates this possibility in principle. Once the central control system is damaged, the system cannot continue to work.

7. Real -time

Beidou users' positioning applications should be sent back to the central control system. The center control system solves the user's three -dimensional location data and then sends it back to the user. Time delay is even longer, so for high -speed exercise, the positioning error has increased.

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