非同步衛星都普勒效應探討及載波回復器之研製

Abstract

本論文探討都普勒效應對非同步衛星的影響.吾人以中頻信號處理的方 式克服都普勒效應,以充分利用高頻積體電路的特性並提出兩段式補償法 還原載波信號.第一級先利用混波差頻大量降低都普勒頻偏再經第二級的 逆向調變和相位追蹤迴路回復信號載波 由模擬以及實驗的結果得知本方 法確實可以補償都普勒效應和還原調變信號中的載波成分進而改善接收信 號品質. In this thesis, the Doppler Effect of the nongeostationary satellite is investigated. A two-stage compensation method is proposed to recover the carrier frequency. In first stage, mixer at the front end is used to beat down greatly the Doppler shift. And in second stage, the reverse modulation andphase tracking loop are adopted to recover the signal carrier. All the processes are made in the intermediate frequency band to take the advantages of RF IC. Not only the simulation but also the experiments confirm that this methodcan indeed compensate the Doppler effect, as well as recover the carrier component of the modulated signal, and, thus, improve the performance of the receiver.