摘要
在卫星数据传输过程中,正交相移键控(QPSK)信号受卫星转发器行波管放大器(TWTA)的AM/AM和AM/PM特性的影响产生畸变,严重影响传输质量。为了解决这个问题,该文研究TWTA的AM/PM变换特性对QPSK调制信号的影响,从理论上推导了存在AM/PM特性的QPSK调制误码率(BER)公式。结合计算机仿真探讨了在TWTA不同的工作点上,AM/PM变换对采用QPSK调制的300Mb/s数据流带来的影响,仿真结果与理论分析趋于一致。最后提出一种相位补偿法来消除AM/PM特性的影响。仿真结果表明经相位补偿后误码率有很大程度的改善。
Travel wave transfer amplifiers (TWTA) in satellites possess amplitude modulation (AM) compression and AM to phase modulation (PM) conversion. For quaternary phase shift keying (QPSK) signals, the AM to PM characteristics strongly influence the data transition quality. This article presents a function for the influence of the bit error rate (BER) on the AM to PM conversion for QPSK modulation. Simulated BER are presented for 300 Mb/s QPSK signals for various TWTA working points. Compensation of the demodulation carrier phase in the receiving terminal is an efficient way to improve AM to PM conversion. Simulations show that the transmission quality is significantly improved.
出处
《清华大学学报(自然科学版)》
EI
CAS
CSCD
北大核心
2008年第4期502-505,共4页
Journal of Tsinghua University(Science and Technology)
基金
清华-高通联合研究基金项目