What kinds of military satellites can be divided into? What are their main functions?

Military satellites can be generally divided into image photography satellites, navigation and positioning satellites, missile early warning satellites, military communication satellites and electronic eavesdropping satellites according to their uses.

1, image photography satellite

LaCrosse radar image reconnaissance satellite. In addition, commercial EOSAT, Landsat and French SPOT satellites are also used for military purposes.

2. Navigation and positioning satellites

There are two GPS systems, one is C/A code, and the positioning accuracy is specified as 100m. It is reported that the actual achievable accuracy of this code is 35m, which is close to the military requirements, so it is reduced to 100 m for commercial use. The other is P code, which is specially used in military affairs, and its positioning accuracy is 18m.

3. Missile early warning satellite

The early warning satellite in the United States is called DSP (Defense Support Program). The satellite weighs 900 kilograms and is located in a fixed-point orbit above the equator. Large infrared telescopes are used to detect infrared signals emitted by missiles. By analyzing the strength of these signals and the difference with the cold background of the earth, the model of the missile is identified, and these signals are sent to the ballistic missile early warning system on the ground to calculate the impact point of the missile.

4. Military communication satellites

Satellites have anti-jamming and anti-jamming measures. There are two kinds of antennas on the satellite, one is multi-beam antenna, which has the ability to receive 6 1 beam; The other is two receiving antennas, 19 beam. The waveform of the antenna is controlled by the ground, and the coverage area of the satellite can be selected. The working life of the satellite is 10 year.

There is a cross communication link between satellites in the constellation (frequency band 60GHz), which reduces the dependence on ground stations; Without the support of the ground station, the communication network can work independently for half a year. In order to strengthen the anti-jamming ability, Milstar has taken measures in frequency band selection and antenna design, which greatly improved the performance.

5. Electronic eavesdropping on satellites

Both the United States and the former Soviet Union have developed and deployed electronic eavesdropping satellite systems. The main function of electronic eavesdropping satellite is to collect the information of ground radar system, monitor the telemetry information of missile test, and judge the performance of missile. It can also eavesdrop on the enemy's operational commands and passwords in combat. Because electronic eavesdropping on satellites is a highly confidential plan, there is little public information.

Baidu Encyclopedia-Military Satellite