干扰条件下接收机减敏机理分析

为了揭示干扰条件下接收机灵敏度下降机理,通过分析接收机对干扰的响应,建立了接收机输入输出模型和输出信噪比模型。分析结果表明,当干扰信号及有用信号在接收机线性范围内时,接收机输出信噪比随着干扰信号增大由基本不受影响至线性下降,可用输入信噪比、输入干噪比、接收机噪声系数、选择性来评估;当干扰信号及有用信号超出线性范围或满足倒易混频条件时,因非线性效应或倒易混频接收机输出信噪比迅速下降。因此,非线性效应并非是引起接收机减敏的惟一原因。试验验证了其结论的正确性,为分析干扰条件下接收机信噪比等性能指标的方法指出了方向和技术途径。

Analysis of receiver desensitization mechanism in the presence of interference

With the responses of receivers to interferences analyzed,the input/output model and signal-to-noise ratio model of receivers were established in order to reveal the mechanism of receivers desensitization under interferences.The results show that the output SNRs of receivers are from influenced slightly decreased linearly with the increase of interferences while interferences and desired signals are within the linear ranges of receivers.In this case the output SNRs of receivers should be evaluated by input SNRs,input interference-to-noise ratios,noise figures and selectivities of receivers.The output SNRs of receivers deteriorate rapidly resulted from nonlinear effects or reciprocal mixing when interferences or desired signals are beyond the linear ranges or interferences meet the requirements of reciprocal mixing.It can be concluded that nonlinear effect is not the only reason for the desensitization of receivers.Test proved that the conclusion was correct.The result provides the guidance and the technical approach for analyzing the performances of receivers such as SNRs under interference.