卫星接收机非线性故障建模与仿真
Modeling and Simulation of Nonlinear Faults in Satellite Receivers
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摘要: 非线性效应导致接收机设备故障以及性能降级一直是卫星通信系统面临的重要挑战。针对这一问题,本文提出了一种基于行为模型的接收机非线性故障分析方法。首先推导分析滤波器内反射干扰在幅频响应上的表现形式,以此构建滤波器故障描述模型。其次利用幅相转换关系对Saleh模型系数进行修正,建立表征放大器在过饱和点下不同程度的非线性故障模型。然后针对相位噪声相关性对振荡器频率稳定性的影响,利用一阶自回归模型表征在不同相关性相位噪声下,振荡器内存在的非线性故障。最后将滤波器、功率放大器和振荡器的故障模型级联,建立接收机射频前端整体的非线性故障模型,并通过星座图、功率谱以及电路仿真三方面对模型进行仿真分析和验证。实验结果表明,本文建立的故障行为模型能有效表征接收机射频前端存在的非线性故障。Abstract: Receiver equipment failure and performance degradation caused by nonlinear effects have always been important challenges faced by satellite communication systems. In response to this problem, this paper proposes a nonlinear receiver failure analysis method based on behavioral models. Firstly, this paper derived and analyzed the manifestation of the reflection interference in the filter on the amplitude-frequency response, so as to construct the fault description model of the filter. Secondly, the coefficients of the Saleh model were corrected by the amplitude-phase conversion relationship, and the nonlinear distortion model that characterizes the amplifier in different degrees under the oversaturation point was established. Then, in view of the influence of phase noise correlation on oscillator frequency stability, a first-order autoregressive model was used to characterize the nonlinear faults in the oscillator under different phase noises with different correlations. Finally, the fault models of the filter, power amplifier and oscillator were cascaded to establish the overall nonlinear fault model of the receiver RF front end, and the model was simulated, analyzed and verified through three aspects: constellation diagram, power spectrum and circuit simulation. The experimental results show that the fault behavior model established in this paper can effectively characterize the nonlinear faults in the radio frequency front end of the receiver.