Bandpass Sampling Techniques for Nonlinear Communication Channels

• Main Authors: Hai-Hsing Lin, 林海興
• Other Authors: Ching-Hsiang Tseng
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/34884872417021683909

碩士 === 國立海洋大學 === 電機工程學系 === 90 === Much attention has been given to satellite communications in recent years. Owing to the growing demand for high-efficiency data transmission and the power-limited nature of satellite communications, it is very important to make the best use of the limit power and bandwidth of a satellite to ensure efficient transmission. For a digital satellite system, operating the power amplifier of the satellite at or near the saturation point provides the most effective use of the power. However, due to the nonlinear characteristics of the power amplifier at its saturation point, the satellite communication channel is generally considered as a nonlinear channel. For a communication channel, an input signal often has bandpass characteristic. In this situation, if the communication system is nonlinear, the output signal could be a bandpass signal with multiple frequency bands. For sampling bandpass signals with multiple frequency bands, the result developed by previous researchers only applies to nonlinear systems up to the third order. This limits its application to nonlinear systems with a higher order. Take the satellite communication channel as an example, earlier research indicates that it can be described by a fifth-order Volterra series. For this kind of application, bandpass sampling techniques for nonlinear systems up to the fifth order will be appreciated. In this thesis, we develop bandpass sampling criteria for nonlinear systems up to the fifth order, and verify the accuracy of the bandpass sampling criteria by computer simulation. By choosing an appropriate sampling frequency using the developed bandpass sampling criteria, we can avoid the aliasing effect when taking samples of the output of fifth order nonlinear systems.