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自由空间光通信中,为了兼备自带符号同步和调制符号长度固定等优点,提出了一种新的光标识双幅度脉冲位置调制方法(FDAPPM),分析了它的符号结构,传输速率和湍流信道中的差错性能。采用最大似然检测时,推导出高信噪比时FDAPPM误码率的简单近似值表达式,并给出系统的分集级数和调制增益。最后与OOK、PPM、FDPIM和FDAPIM等方法进行比较。结果表明:在相同的湍流条件下,FDAPPM的传输速率和差错性能均优于FDPIM和FDAPIM;相对于PPM系统,其传输速率高,不需要符号同步,接收器复杂度大为简化;且符号长度固定,不会引起调制器等待或缓冲器溢出。
In free-space optical communication, a novel method of dual amplitude pulse position modulation (FDAPPM) for light identification is proposed in order to combine the advantages of self-contained symbol synchronization and constant length of modulation symbols, and its symbol structure, transmission rate and turbulence channel In the error performance. When maximum likelihood detection is adopted, a simple approximation expression of FDAPPM bit error rate at high signal-to-noise ratio is derived and the system diversity order and modulation gain are given. Finally, compared with OOK, PPM, FDPIM and FDAPIM methods. The results show that the transmission rate and error performance of FDAPPM are better than that of FDPIM and FDAPIM under the same turbulent flow conditions. Compared with PPM system, the transmission rate of FDAPPM is high, the symbol synchronization is not needed and the receiver complexity is greatly simplified. Fixed, will not cause the modulator to wait or buffer overflow.