Mobile Satcom Antenna
MOBILE SATCOM ANTENNA
The most important feature of mobile satcom antenna is that they can provide communication services between mobile users, such as vehicles, aircraft, ships, and even personal communication, and have the advantages of wider coverage area, not bound by geographical barriers and user movement restrictions, making fiber optic communication unparalleled, so they are increasingly valued and welcomed. With the continuous development of international communication satellites, especially since 1982, when the international mobile satellite officially provided commercial services, satellite mobile communication has attracted the keen interest and great attention of countries around the world, and the emergence of global personal communication services. What is the difference between mobile communication satellites and general communication satellites?
One is the same as the general communication satellite for geostationary orbit. Its typical representative is Inmarsat 3, which was used for communication during China's flood fighting in 1998. However, because of the long distance of communication, weak signal and large ground equipment, it can generally only be used for communication of large mobile users such as ships, aircraft and vehicles. Even the advanced portable ground terminal, before the call, but also to find the international mobile satellite, the call can not move. However, geostationary mobile communication satellites have been developed to provide services for personal cell phones, and the "Asia Cellular System" (ACeS), which lifted off in 2000, is the first one.
Another type is the low orbit mobile communication satellite system. It was conceived in the late 1980s and has become a hot spot for mobile communication satellite development. This is because of its low orbit, generally at an altitude of about 500~1500 km. This low-orbiting satellites because of the signal transmission route is short, so the signal attenuation loss is very small, the signal time delay is also very short, almost imperceptible, can get the most effective frequency multiplexing, and can achieve truly global coverage. This mobile communication satellite, the mass and volume are not large, so its development and production cycle is short, the development cost is lower than the large satellite.
Mobile communication satellite transmitting and receiving antenna size and transmitting power are generally high, and the use of rain attenuation and signal transmission loss of small L-band transmission signal, the purpose is to reduce the size of the ground user terminal, easy to carry, to ensure the quality of communication.
Mobile communication satellites can not only provide communication services for large mobile users, such as ships, aircraft and vehicles, but also enable personal cell phones to communicate directly with satellites, and the launched "Yi Xing" and "Global Star" are typical. In specific cases, they demonstrate the superiority that other communication systems do not have. For example, for the expedition to the polar regions, the "Yi Xing" cell phone can communicate with the country very easily, dwarfing other means of communication; in India and Taiwan, other means of communication were damaged by the earthquake, the "Yi Xing" cell phone can still In the case of earthquakes in India and Taiwan, where other means of communication were damaged, the "Essing" mobile phone still worked reliably to ensure communication with the outside world.
Mobile communication satellites are capable of providing direct voice communication services to users, but they cannot retransmit TV programs. The retransmission of TV programs is done by live TV satellites. Users can watch or listen to the programs transmitted by satellite directly, but generally only at a fixed location. Live TV satellites have become a hot topic of contemporary development. The characteristics of such satellites are roughly similar to those of mobile communication satellites, i.e., they transmit downlink signals at high power, have large solar arrays (guaranteed to provide power above the kilowatt level), high-precision orbit control and antenna pointing. All these are designed to reduce the burden on ground users and miniaturize their receiving terminals. In other words, it leaves the difficulties to the satellite and gives the convenience to the users.
Contemporary live TV satellites use digital video compression technology, thus greatly saving the band width and increasing the rate of transmitting video data. This satellite using digital video compression technology, can provide hundreds of television programs, families only need to install a diameter of 0.45 m antenna and receive decoder, you can watch high-quality satellite television programs directly on the TV set.