Heterodyne System Performance with Amplitude-modulated Sinewave Inputs in Radar and Binary Communication Applications

• Main Authors: Cheng, Kung-Chih, 鄭光志
• Other Authors: Rainfield Y. Yen
• Format: Others
• Language: zh-TW
• Published: 1991
• Online Access: http://ndltd.ncl.edu.tw/handle/44591762463002036096

碩士 === 淡江大學 === 資訊工程研究所 === 79 === 　　In the conventional heterodyne detection system, either for radar applications (CW or pulsed radar), or for binary communication purposes ( ASK, FSK, PSK, etc) , the transmitted signals are in the form of sinuoidal wave and the mostly encountersed noise is the white Gussian noise. Theoretical treatments consider the sinewave signal to be of constant amplitude. 　　However, when the signal travels through the turbulent atmosphere, not only it will be pertubed by the noise, its constant amplitude feature could also be perturbed. Therefore, it is likely that the signal is an amplitude-modulated sinewave rather than constant amplitude. The result is that the incoming signal becomes a narrowband random process. 　　In this paper, we assume the signal to be a narrowband Gaussian process in a white Gaussian noise environment. We consider two application areas: one for rafar applications; one for binary communications. With detailed signal analysis, we then evaluate the performances. for these applications. Comparisons are made between the cases of constant amplitude and modulated amplitude. 　　As expected, the performance in modulated-amplitude case is degraded as compared to the constant-amplitude case, either for radar applications or for binary communications.