What satellites are there? What's the use?

1, meteorological satellite:

It is used to monitor the meteorological information of the cloud and provide the latest meteorological situation and long-term meteorological analysis. There are two series of meteorological satellites in China: polar orbit and static. Polar-orbiting satellites fly around the north and south poles and cross the equator for about 102 minutes at a time, with an orbital height of about 830 kilometers.

The satellite passes through the same place, so it is also called "near-polar sun synchronous orbit". Its advantage is that it can be observed anywhere in the world, mainly used for weather forecasting, ecology, environmental monitoring and climate change research. Military satellite: mainly used for military purposes and monitoring important military targets.

2. Communication satellites:

Mainly used for civil use, providing various communication purposes, such as TV broadcasting, IP communication network, telephone network, etc. Communication satellites adopt a series of new technologies such as Ka-band, laser communication and electric propulsion, and the total communication capacity exceeds 20 megabits per second.

Thus, it exceeds the total capacity of all communication satellites previously developed in China, indicating that China's satellite communication has entered the Qualcomm era, realizing the real broadband application of autonomous communication satellites, and filling the gap of China's resource satellites in this field: mainly used for resource exploration, etc.

3. LEO satellites:

LEO satellites have an orbital altitude of 200-2000 kilometers, and satellites within this altitude range are LEO satellites.

Generally, it is a large satellite system composed of multiple satellites, which can process real-time information and realize functions such as communication, remote sensing and navigation. The group benefit of constellation scale may exceed that of large satellites with comprehensive functions and outstanding performance.

LEO satellites are also used for mobile phone communication. Satellite orbit height is low, transmission delay is short and path loss is small. The communication system composed of multiple satellites can achieve real global coverage, and frequency reuse is more effective.

Technologies such as cellular communication, multiple access, spot beam and frequency reuse also provide technical support for LEO satellite mobile communication. LEO satellite is the latest and most promising satellite mobile communication system.

4. Military satellites:

It can provide accurate position, speed and time information for ground vehicles, planes, surface ships, ground troops and even individual soldiers, and can accurately guide missiles and artillery shells, greatly improving the use efficiency of weapons.

Military satellites are required to be fast, accurate, confidential, continuous and flexible, so advanced technologies such as adaptive antenna zeroing, on-board processing and inter-satellite link are often used to improve reliability, survivability and anti-interference ability, reduce dependence on ground stations, and play a key role in large-capacity and fast information transmission required by operations.

5. Resource satellites:

Earth resources satellite is a kind of "sun synchronous satellite" with medium altitude, with perigee of 905 km and apogee of 9 18 km, so its orbit is close to circular; Cycle once every 103.267 minutes, from north to south and from south to north. The earth turns 14 times a week, and takes a photo every 25 seconds.

There are two kinds of "photographic" instruments (called sensors) on the earth resources satellite. One is an inverse beam tube TV camera, which is similar to a TV camera; The other is a multispectral scanner, which can separate and record the electromagnetic waves reflected from the ground according to their wavelengths.

The optical signals received by these instruments are converted into voltage signals and recorded on magnetic tapes. When the satellite passes over the ground receiving station, the ground station records the voltage signal sent back by it with magnetic tape, and then it is processed by computer to become an optical signal and re-imaged on the photosensitive material. This is a satellite photo.

Baidu Encyclopedia-Meteorological Satellite

Baidu encyclopedia-communication satellite

Baidu Encyclopedia-LEO Satellite System

Baidu Encyclopedia-Military Satellite

Baidu Encyclopedia-Resource Satellite