Three-part Composition of China's Beidou Star
The BeiDou navigation and positioning system (referred to as the BeiDou system) consists of three parts: the space constellation, the ground control center system and the user terminals.
1. Space Constellation
The space segment of China's Compass/BeiDou navigation system (COMPASS) under construction is planned to consist of five geostationary orbit satellites and thirty non-geostationary orbit satellites, providing two
The space segment is planned to consist of five geostationary orbit satellites and thirty non-geostationary orbit satellites, providing two kinds of services, i.e. open service and authorized service. The satellites are located at a distance of 36,000 km from the ground, over the equator at longitudes 80 and 140 East, respectively, and carry out the task of relaying two-way radio signals between ground control centers and user terminals. There is also a backup satellite positioned over the equator at 115.5 East longitude. The satellite weighs 980kg and has a lifetime of not less than 8 years.
2、Ground Control Center System
The ground control center of BeiDou system includes the main control, orbit measurement station, altimetry station, correction station and calculation center, which is mainly used to measure and collect correction navigation and positioning parameters, complete orbit measurement and adjust the satellite's operation orbit, attitude, prepare ephemeris, form user positioning correction data and position the user, i.e., it is responsible for the transmission and reception of the radio signals as well as monitoring and managing the whole working system.
3、User equipment
According to the BeiDou user machine and the application of different environments and functions, usually BeiDou user machine has five types:
(1) Ordinary type. This type of user machine can only carry out positioning and point-to-point communication, suitable for general vehicles, ships and portable and other users of positioning and navigation applications, can receive and send positioning and communication information, and two-way communication with the central station and other user terminals.
(2) Communication type. Suitable for field operation, hydrological measurement, environmental testing and other types of data collection and data transmission users, can receive and send short messages, telegrams, and the central station and other user terminals for two-way or one-way communication.
(3) Timing type. It is suitable for users of timing, calibration, time synchronization, etc. It can provide time synchronization accuracy of tens of nanoseconds.
(4) Command type. Command-type user machine is for a certain number of users of the higher group management department used, in addition to all the functions of the ordinary user machine, but also be able to broadcast broadcast information and receive the center control system sent to the user's location of the communication information. Command-type user machine can be divided into one, two, three. Among them, the first level of command-type user machine, the user under the jurisdiction of the ordinary user machine; the second level of command-type user machine, the user under the jurisdiction of the first level of command machine users; three levels of command-type user machine, the user under the jurisdiction of the second level of command machine users.
(5) Multi-model user machine. This kind of user machine can receive Beidou satellite positioning and communication information, but also can use GPS system or GPS augmentation system navigation and positioning, suitable for users who have higher requirements for location information.
It can be seen that the global satellite communication system mainly involves three parts: the space segment, the ground segment and the user end. The space segment mainly includes satellite manufacturing and satellite launching, because it involves core technology and core interests, and is mainly invested by the state in the construction; while the ground segment contains a lot of content, including basic devices, terminals, base stations, etc., with high industrial value and certain high-tech content, which is the focus of the relevant enterprises' competition; and the user side is mainly some terminal services, such as navigation, measurement, timing and other applications. With the increasing level of terminal intelligence, the user side has penetrated into the daily life of everyone, such as we go out and open the Gaode search destination, similar demand in this area will be more and more, this piece of the market is full of imagination.
