大气信道中的大气湍流是影响无线激光通信系统性能的主要因素之一, 其引起的强度闪烁效应会对接收信号的提取和还原造成很大干扰。基于Gamma-Gamma概率分布的大气湍流信道统计模型, 研究了利用副载波相移键控(PSK)强度调制技术的大气光通信系统的误码特性; 推导了副载波二进制相移键控(BPSK)及开关键控(OOK)两种调制模式下的系统误码率表达式; 对在一定条件下的大气光通信系统, 比较了副载波BPSK和OOK两种调制模式的误码特性; 分析了链路特征、接收口径尺寸、通信波长和天顶角等因素对系统误码率的影响。结果表明, 增大接收孔径和通信波长都能有效地降低系统误码率, 而天顶角的增大则会使系统误码率增加, 副载波BPSK调制模式的误码特性要优于OOK调制模式的误码特性。

In atmospheric channel, atmospheric turbulence is one of the main factors that degrade the performance of atmospheric optical communication systems. Turbulence-induced intensity scintillation often reduces the capability of receiver to extract and recover information contained in the modulated optical wave. Based on the Gamma-Gamma distribution, the bit error rater (BER) performance of atmospheric optical communication system using subcarrier PSK intensity modulation is investigated. The bit error rate for turbulent channel is derived for subcarrier BPSK and OOK modulation schemes. Under some conditions, comparison is given about the BER performance of the above-mentioned two modulation schemes. The influences of link character, aperture diameter, wavelength and zenith angle on the BER are evaluated. Results show that the BER is effectively reduced by increasing aperture and wavelength and increases with increasing the zenith angle. It is also shown that the BER performance of systems employing subcarrier BPSK modulation is much better than that of compatible systems employing OOK modulation.