The Effects Of GaAs Materials And GaAs Devices Performance On The Small Receiving Systems Of Satellite Communication Station

With the development of the subject of semiconductor and microelectronics, the communication technology is changing quickly. Satellite communication possesses the function that is a farther communication distance, a large covered range and capacity of channel. Because of the improvement of materials and devices performance, the satellite communication has rapidly developed. The microwave or millimetre-wave communication represented by the satellite communication stimulate the improvement of semiconductor materials and devices. My subject is coming under the above conditions. The effects of semiconductor materials and devices are researched from the satellite communication system and the effects of each other. A new object is raised to semiconductor materials and its devices which can be obtained.Due to the good performance of GaAs devices of high frequency, high electron mobility and low noise, the high frequency devices are mostly made of GaAs materials now. Based on the many existing schemes of crystal growth, the LEG with magnetic field(M-LEC) is chosen as a manner of producing better quality crystal. The dislocation-free, low defects densities crystal are acquired, in which the impurities concentration is decreased, their distribution are uniform, and the GaAs crystal has high uniform and purity characteristics.Satellite communication is restricted by the power and the occupied frequency band width, so the improvement of the performance for receiving system is necessary. In this paper, three method are proposed. The two among them are that the higher information transmission data rate will be given in the increasement of the signal transmitted power, and another is got through the compression of video signal data rate. The main program is designed by Matlab language, others by C language. The simulation experiments are made in the Gaussian and Rayleigh channel. The first two methods use the advanced GaAs materials and devices to reduce the noise of receiving system. Without increasement of the transmitted power, the system margin gains 1 dB compared to the conventional project margin, the information rate can be increased 2 Mbps or more. The video would be impaired by the last method, but it can achieve the quality of PAL/NTSC program in existence, the data rate will be increased in 2 Mbps additionally.