Communication satelliteLike an international messenger, as a radio communicationRepeater station。Collect various "letters" from the ground, and then "deliver" them to users in another place.Because it is "standing" at 36000kmhigh altitudeTherefore, its "delivery" coverage is particularly large, and one satellite can be responsible for 1/3 of the communication on the earth's surface.If onGeostationary orbitBy evenly placing three communication satellites on the, global communication can be realized except for the South and North Poles.
According to different tracks, it can be divided intoGeostationary orbitCommunication satellite, largeElliptical orbitCommunication satellites, medium orbit communication satellites, low orbit communication satellites, and other orbit satellites (such as communication satellites for equipment such as Mars rovers, lunar rovers, etc., in the orbit of the moon, Mars, or other celestial bodies[1]）。
2 Different service areas
According to different service areas, it can be divided intoIntelsat、Regional communication satelliteAnd domestic communication satellites, and communication satellites with other planet equipment[1]。
3 According to different purposes
It can be divided intoMilitary communication satellite、Civil communication satelliteAnd commercial communication satellites, other communication satellites[1]。
4 According to different types of communication services
OneGeostationary orbitCommunication satelliteIt can cover about 40% of the earth's surface, so that any ground, sea and air communication stations in the coverage area can communicate with each other at the same time.Three geostationary orbit communication satellites distributed at equal intervals over the equator can realize global communication except for parts of the polar regions.Communication satellite is one of the earliest and most widely used satellites in the world. The United States, the former Soviet Union/Russia, China and many other countries have launched communication satellites.
When the satellite receives a weak signal from a ground stationradioAfter the signal is sent, it will automatically turn it into a high-power signal, and then send it to another ground station, or to another communication satellite, and then send it to the ground station on the other side of the earth. In this way, we will receive the signal sent from far away.
The communication satellite generally adopts the geostationary orbit, which is located 35786 kilometers above the Earth's equator.In this orbit, the satellite rotates around the earth from west to east at a speed of 3075 meters per second, and the time of one round of the earth is 23 hours, 56 minutes and 4 seconds, which is just the same as the time of one round of the earth's rotation.Therefore, from the ground, the satellite seems to hang in the sky, which makes the work of the ground receiving station much more convenient.The antenna of the receiving station can be fixed at the satellite, and can communicate day and night without interruption. It is not necessary to "wiggle" around like tracking those moving satellites, making the communication time intermittent.Communication satellites have undertaken all intercontinental communication services and television transmission.
Communication satellite is one of the earliest and most widely used satellites in the world. Many countries have launched communication satellites.
On December 18, 1958, the United States successfully launched the world's firstCommunication satelliteThe Skoll.On April 6, 1965, the United States successfully launched the world's first practical geostationary communication satellite:International communicationsSatellite 1.So far, this type of satellite has developed to the eighth generation, and each generation has improved in size, weight, technicality, communication ability, satellite life, etc.
The communication satellite of the former Soviet Union was named "Lightning".Including Lightning 1, 2, 3, etc.Because of the vast territory of the former Soviet Union, most of the "Lightning" satellites are not in geostationary orbit, but in aEccentricityBigElliptical orbitOn.
China's first geostationary communication satellite was launched on April 8, 1984, and was named "Dongfanghong II". So far, five satellites have been successfully launched.These satellites have successively undertaken radio, television signal transmission, remote communication and other work, and played a huge role in national economic construction.
