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利用星上微波光子技术,将多个频段微波信号调制到光域,可解决数据在星上的高速处理和星间远距离传输等问题。当多频段微波信号进行光学调制时,交调失真是影响星上多频段微波信号光域传输性能的重要因素。研究了星上双频段、每个频段内2信道的微波信号光学调制方法,分别推导了Ku、Ka波段微波信号的输出信号噪声失真比(SNDR)和无杂散动态范围(SFDR)表达式,分析了各次谐波和各阶交调失真分量对链路性能的影响,获得了保证链路输出SNDR最优的最佳直流偏置相位和调制系数。利用OptiSystem软件建立了仿真模型,并进行了仿真验证。研究结果表明,Ku频段中非线性交调分量包括自频段三阶交调(IMD3)分量、频段间IMD3分量和频段间二阶交调(IMD2)分量;Ka频段中非线性交调分量包括自频段IMD3分量、Ku频段IMD2分量、Ku频段二次谐波(HD2)分量以及频段间IMD3分量。对于Ku频段信号,当调制系数和直流偏置相位分别为0.17和0.535π时,SNDR取得最优值21.50dB;对于Ka频段信号,调制系数和直流偏置相位分别为0.22和0.525π时,SNDR取得最优值15.32dB。
Using on-board microwave photon technology, the microwave signals in multiple frequency bands are modulated into the optical domain, which can solve the problems of high-speed processing of data on the satellite and long-distance transmission between stars. When multi-band microwave signals are modulated by optical signals, crosstalk is an important factor that affects the transmission performance of multi-band microwave signals in the optical domain. The optical modulation methods of microwave signals in dual frequency bands and two channels in each frequency band are studied. The expressions of the output signal noise distortion ratio (SNDR) and spurious free dynamic range (SFDR) of Ku and Ka waveband microwave signals are deduced. The influence of the harmonics and the crosstalk components of each link on the link performance is analyzed, and the optimal DC offset phase and modulation coefficient to ensure the optimal SNDR of the link output are obtained. The OptiSystem software is used to establish the simulation model and the simulation is carried out. The results show that the non-linear intermodulation components in the Ku band include the third-order intermodulation (IMD3) component in the frequency band, the IMD3 component in the frequency band and the second-order intermodulation (IMD2) component in the frequency band. Band IMD3 component, Ku band IMD2 component, Ku band second harmonic (HD2) component, and inter-band IMD3 component. For Ku-band signals, SNDR achieves an optimum of 21.50 dB for a modulation factor and DC offset phase of 0.17 and 0.535π, respectively. For a Ka-band signal, the modulation factor and DC offset phase are 0.22 and 0.525π, respectively. The SNDR Obtain the optimal value of 15.32dB.