QPSK扩频信号I、Q正交性测量方法研究  

Study on I,Q Orthognality Measurement Method for QPSK Spread Spectrum Signals

作　　者：王缚鹏 何巍巍[1,2] 

机构地区：[1]河北省卫星导航技术与装备工程技术研究中心,河北石家庄050081 [2]武汉大学,湖北武汉430072

出　　处：《无线电工程》2014年第1期24-27,共4页Radio Engineering

基　　金：国家高技术研究发展计划("863"计划)资助项目(2012AA121802)

摘　　要：根据实际应用背景,针对四相相移键控(QPSK)调制扩频信号的特性,讨论了用扩频接收机进行I、Q两路信号正交性的测试方法。QPSK调制中,I、Q支路载波相位正交性能够有效反映发射信号质量。高信噪比下的信号正交性测试能够通过测量仪器完成。对于在轨卫星的下行扩频信号,接收信号信噪比较低,利用仪器无法测出正交性,因此提出一种利用扩频接收机对卫星下行信号进行接收处理,解扩后提取即时的I、Q支路载波相位计算其正交性的方法。实验结果表明,该方法可有效完成低信噪比情况下的扩频QPSK调制信号的正交性测试。Based on the practical application background,aiming at the characteristics of the QPSK modulated spread spectrum signal,the paper discusses the measuring method of its I, Q signals＇ orthogonality. The traditional method is based on the measuring equipment to measure the orthogunallity of the spread spectrum signal. However, for the down-link spread spectrum signal of the satellite in orbit,when the signal arrives at the earth, its power becomes too weak, and deeply hides inside the noise. It is impossible for the equipment to measure the I, Q signals＇ orthogoanlity precisely. Therefore, the paper propsoes a method of measuring I, Q signals＇ orthogonality for the QPSK modulated spread spectrum signals,based on the spread spectrum receiver. The receiver receives the QPSK spread spectrum signal,completes the capture tracking, at the same time measures the carrier phase for the I, Q signals individually. After subtracting their measured carrier phases,we can acquire the I, Q orthogonallity of the measured signals.

关 键 词：QPSK调制扩频信号 载波相位差 数字接收机 正交 

分 类 号：TN911.72[电子电信—通信与信息系统]