噪声测试系统精度有源-无源联合测量评估方法

通过在无源器件后置有源增益器件提高被测件整体的增益,抑制系统中非零误差对噪声测试结果的影响;结合单一有源器件及级联有源-无源器件的2次噪声测试结果,采用噪声系数直减法,将系统测量评估精度的表征参数由噪声系数转化为级联无源器件的插损值;并以具有更高插损测量精度的矢量网络分析仪插损测试结果作为参考基准,定量评估噪声测试系统的精度.经与传统无源测量评估方法的实测对比验证得,在2~40 GHz频段内,所提方法对基于Y因子法的噪声测试系统的评估精度为–0.5~0.5 dB,对基于矢量冷源法的噪声测试系统的评估精度为–0.3~0.3 dB,评估精度波动范围均小于被测系统的2倍测试不确定度,较传统无源测量评估方法评估精度提升了3倍以上.

Outage performance of multihop free-space optical communication system over exponentiated Weibull fading channels with nonzero boresight pointing errors

The outage performance of the multihop free-space optical(FSO) communication system with decode-and-forward(DF) protocol is studied by considering the joint effects of nonzero boresight pointing errors and atmospheric turbulence modeled by exponentiated Weibull(EW) distribution. The closed-form analytical expression of outage probability is derived, and the results are validated through Monte Carlo simulation. Furthermore, the detailed analysis is provided to evaluate the impacts of turbulence strength, receiver aperture size, boresight displacement, beamwidth and number of relays on the outage performance for the studied system.