Of the new technologies of satellite communications systems - satellite communications, optical comm - News - Business News

Satellite Communicate Communication technology can not satisfy the cause of more rapid development of this, scientists need to constantly look at improving the technical means of satellite communications, the use of lasers into high-tech satellite communications is a developing trend. Present, the carrier is a microwave satellite communications, data transmission rate of 50 megabytes per second, very difficult to achieve than the above, mainly due to communication satellite antenna can not accommodate the large volume, while the future of satellite communications data rate requirements of work in each seconds to several hundred, the number of Gigabit, therefore, can only be achieved by a laser communication, as in outer space laser communication, the impact of the atmosphere can not give full play to its advantages. According to expert estimates, the ratio of satellite laser communications Microwave communication Data transmission rate of a magnitude of the case, the ante nna aperture size of a comparable decrease the number of satellite microwave communications class. Therefore, future laser communication between satellites is very promising. Global communications in order to solve the "double jump" method of satellite communication signal delay caused by the malpractice of "inter-satellite laser link" technology, from communications satellite laser communications between the methods used will get unexpected advantage. Experts estimated that in ideal circumstances, the use of laser for vector space radio communications, if the bandwidth is 4 kHz telephone channels, can accommodate 10 billion, then Road; if color TV Bandwidth of 10 MHz, you can also send l000 million program without any interference. The reason is: the laser frequency pure, highly concentrated energy, a very fine beam, the wavelength in the microwave to IR Between, therefore, unique to the high laser intensity, high color, high coherence and high directivity, and many other f eatures, for inter-satellite communication link, you can get larger, narrower beam, higher gain faster and stronger anti-interference and confidentiality of a series of advantages and better, so that the development of space laser communications satellites as the best carrier. United States is currently under study results show that the use of "Rb Glass Laser "and" GaAs lasers, "the most appropriate inter-satellite link applications. Their light technology is simple, free from the receiver signal phase effects, and long working life, high reliability, its comprehensive performance is better than other lasers. Satellite laser communications major technical problem is how accurately high-data-rate transmission. Currently being tested in the satellite laser communication data rates between 100 to 1000 Mbps communications over distances up to 70,000 km. Between terrestrial and satellite laser communications will be the impact of the atmosphere and clouds, and satellite than to f ace the impact of satellite on the ground is even more serious. The solution, first using multiple ground stations to improve the cloud-free laser Launch Probability; second is the use of aircraft receiving ground station signal, and then fly to the clouds, the beginning and in the flight laser communication between satellites. Satellite laser communication information transmission process is generally: from low-orbit satellite data relay the information transmitted to the satellite ground station or data transmission; or according to the location of low-orbit satellites, by the second laser communication transfer to another line of satellite data relay, the last, then the data transmission to ground stations. This transfer case of synchronous satellite orbit, you can use two-synchronous communications satellite to achieve the East, the communication between the Western Hemisphere. Massachusetts Institute of Technology and the McDonnell Douglas Aircraft Company are working o n the technical means of satellite laser communications, and has achieved some success. Some of the data rate is already 100 ~ 200 Mbps, inter-satellite distance of 72,000 km. Germany is also designing a satellite laser communication systems, data rate at 100 Mbps, communication distance of 73,000 km. In addition, a variety of satellite communication systems using geostationary orbit satellites, satellite ground distance and weak signal from passing, and then transferred by each transfer, so that the number of waves back and forth to 4, will be a delay. 1 second, the inconvenience to the voice communication. In recent years, proposed the development of the international community of small low-orbit satellites, can use different orbit satellites relay the signal ground users, the general altitude of 1000 km. As low orbit, satellites and ground equipment can simplify the user, this LEO satellite communication system can be used for internal communication system, but also with the increase in the number of satellites used for global communications. Of course, such a system there are many technical problems. One of them is to make between any two points on Earth users can in constant motion between the satellite and the satellite communications link established, it must be resolved between the satellite and the satellite signal transmission and distribution of satellite technology to automatically deal with the problem. In short, the future of satellite communications systems technology will further the development of communication satellites will further expand the scope of application, the prospects are very bright. [Key words]: Satellite Communications Optical Communication GSM Comment Large In Small

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