摘 要:Galileo/GPS偽衛(wèi)星系統(tǒng)對載波頻率的性能有著很高的要求,提出了采用PLL技術和DDS技術結合應用的方法來設計Galileo/GPS高精度偽衛(wèi)星頻率合成器的設計方案,E1/L1波段載波頻率經過二次混頻后輸出。混頻模塊通過ADS仿真,輸出的載波頻率能滿足系統(tǒng)雜散抑制指標。最后基于此頻率合成器方案制作PCB板且經過調試,E1/L1波段載波頻率的各項指標符合設計要求。關鍵詞:Galileo/GPS偽衛(wèi)星; ADS; 雜散; 載波頻率; 混頻模塊
中圖分類號:TN911文獻標識碼:A
文章編號:1004-373X(2010)15-0085-03
Design and Realization of Carrier Frequency at Galileo E1/GPS L1 Band
LUO Wan-hui, ZHANG Fu-hong, ZHU Huai-huan
(School of Communication Engineering, Hangzhou Dianzi University, Hangzhou 310018, China)
Abstract: A design scheme that adopts PLL and DDS technologies to design Galileo/GPS high-precision pseudolite frequency synthesizer is proposed since Galileo/GPS pseudolite system has a very high demand to carrier frequancy. E1/L1 band carrier frequency is outputted after the second mixing. ADS simulation of mixing module indicates that the output carrier frequency can satisfy the stray suppression index of system. The PCB board was made according to the scheme of the frequency synthesizer and debugged. The testing results show that each index of E1/L1-band carrier frequency meets the design requirements.Keywords: Galileo/GPS pseudolite; ADS; stray suppression index;carrier frequency; mixing module
收稿日期:2010-03-23
0 引 言
Galileo計劃是由EC(歐盟委員會)和ESA(歐洲空間局)共同發(fā)起并組織實施的歐洲民用衛(wèi)星導航計劃,旨在建立歐洲自主、獨立的民用全球衛(wèi)星導航定位系統(tǒng),它與國際上現有的全球衛(wèi)星導航定位系統(tǒng)相比,具有更佳的覆蓋率和更高的精度和可靠性,并且能夠與其他兩個導航系統(tǒng)——GPS和GLONASS兼容[1]。
根據Galileo/GPS高精度偽衛(wèi)星的功能需求,本文給出的頻率合成器需要合成Galileo E1,Galileo E5,GPS L1三個波段的載波、子載波參考時鐘、偽碼參考時鐘和DAC參考時鐘,其中Galileo的E1和GPS的L1中心頻率重疊,使其在一個寬頻帶內有最大的兼容性和共用性,在這種寬帶溢出并重疊應用下,它能保證精密的電離層補償。E1~L1段信號中心頻率為1 575.42 MHz(能夠模擬高動態(tài)情形下的多普勒頻移)
1 頻率合成器總體方案介紹
本文的頻率合成器要求頻率較高,且模擬多普勒頻移時需要很高的頻率分辨率和快速的頻率跳變,如果單獨采用鎖相環(huán)來完成,為得到高的頻率分辨率,則必然需要很大的N值,這不利于低相噪、低雜散的目的。……