I.The communication capacity is increasing and the cost is obviously decreasing
II.The size and weight of satellites are increasing, the number of on-board transponders is increasing, and the antenna diameter of the earth station is reducing.
III.The development of micro earth station communication network can meet the needs of those who want to build their own satellite dedicated communication network. These private networks are generally distributed in remote areas, quite scattered, with less users and sparse routes.
I. VSAT communication is not affected by terrain and surface features, and is applicable to places where other communication means are difficult to reach.
II. The equipment installation is fast. When conditions are met, it takes 1-2 days to open a small station.
III. The communication quality is high. Various automatic error detection and correction functions are adopted in the network. The bit error rate is low. Under normal condition, it is less than 10-7.
IV. The advanced data processing technology, delay compensation and local polling (p011) function are used to shorten the system response time.
V. DAMA technology is adopted to make full use of the satellite channels.
VI. The VSAT terminal equipment has the ability to talk and adopts advanced voice processing technology to ensure voice quality.
Satellite communication is an extension of the development of microwave communication technology. The frequency band used is basically the same as that of terrestrial microwave. The C-band used in China is the same as that of terrestrial microwave relay system. In foreign countries, Ku band marine VSAT can not completely avoid the spectrum overlap with terrestrial microwave relay system from the perspective of development. Therefore, interference coordination between satellite communication and terrestrial microwave relay communication system is inevitable.
In the design of satellite communication, the best modulation mode and multiple access technology should be correctly selected. For the high-efficiency direct circuit, the medium rate data (IDR) plus digital multiplication equipment (DCME) is the best transmission mode.
