幅相不平衡误差对KBR系统测距精度影响分析

摘要

K band ranging system is one of the key equipment of the gravity satellite using low-low satellite to satellite technique. Its performance directly affects the Earth′s gravity measurements , and the amplitude and phase unbalance error induced by quadrature downconversion has an non-negligible impact on KBR′s ranging accuracy. In order to obtain the impact of amplitude and phase unbalance error on ranging accuracy, the article analyzed the transmission of amplitude and phase unbalance error in KBR, and established KBR′s amplitude and phase unbalance error simulation model using MATLAB. Quantitative relationship between amplitude and phase unbalance error and KBR system ranging accuracy is obtained by simulation results and theoretical analysis. In KBR system designing , phase jitter unbalanced error should be controlled within 1 in degree , fixed phase imbalance error should be controlled within 5 in degrees, amplitude jitter unbalanced error should be controlled within 0.5 in dB, and fixed amplitude imbalance controlled within 0.5 in dB.%K频段微波测距(KBR)系统是低-低卫星跟踪卫星(SST-LL)重力测量卫星的关键载荷之一,其性能直接影响地球重力场空间变化率的测定结果,而KBR系统中正交下变频过程引入的幅相不平衡误差对系统测距精度有着重要影响.针对幅相不平衡误差对KBR系统测距精度的影响,通过分析幅相不平衡误差在KBR系统中的传递过程,并结合MATLAB软件建立了KBR幅相不平衡误差仿真模型,理论分析和仿真结果互相验证得出幅相不平衡误差与系统测距精度之间的定量关系.建议KBR系统设计中:1δ相位抖动不平衡控制在1度以内,固定相位不平衡控制在5度以内,1δ幅度抖动不平衡控制在0.5 dB以内,固定幅度不平衡控制在0.5 dB以内.