无源探测接收系统设计中的非线性分析

Analysis of Nonlinearity in Passive Coherent Receiving System

摘要:

在多频探测环境下,无源探测接收系统的输出端将产生由于互调和交调而导致的虚假干扰。文中首先给出了两种实际工程上可行的测试方法；并探讨了非线性失真产生的机理及其对整个接收系统所产生的影响,对三阶互调、三阶截点和1 dB压缩点三个衡量接收机线性度的指标作了全面分析；最后研究了系统的三阶截点与各模块的三阶截点、增益以及接收机各级的选择性等指标间的关系。

Abstract:

The mathematics of three-order inter-modulation (IM) was surveyed in a dedicated passive receiver system. The worst case IM was a third-order effect occurring in amplifiers and mixers. The false alarm caused by IM in multi-frequencies background was pointed out, and two kinds of available linearity test method was presented. A thorough analysis of three order IM, three order intercept point and 1dB compressive point was explored, and then relationships between them were discussed in greater detail. Their advantages of Low noise and high burnout resistance were contrasted with the problems of conversion gain and high-required local oscillator. The influences of each receiver modules on system’s three-order intercept point power levels were discussed in the end.