L波段有源冷噪声源研究

本文介绍了有源冷噪声源的应用背景及发展现状。根据微波场效应晶体管常温下输出稳定低噪声的特性，以Avago公司的两种典型pHEMT晶体管为核心器件进行了ADS仿真设计，研制出两款有源冷噪声源。给出了对设计的两款器件的技术指标进行验证的L波段周期定标辐射计设计框图。仿真结果表明，以pHEMT型晶体管为核心器件设计成的L波段有源冷噪声源能输出稳定低噪声。

A Novel Transmission Scheme of HF Time Signals based on #br# Spread Spectrum System and its Feasibility Analysis

The application of spread spectrum signal in HF time service system will help to improve the quality of time service.Considering the complexity of HF channel and the limitation of system bandwidth,this paper proposes a novel scheme to transmit HF time signal based on the relative time interval between two spread spectrum signals,and analyses its feasibility.The basic technical ideas of the scheme is expounded,and then theoretical analysis is carried out to verify that compared with the conventional scheme,the proposed scheme can significantly reduce the probability of the time signal detection error of the receiver.Compared with the conventional scheme,the proposed scheme is better realized to coordinate the compatible transmission of the two HF time signals of UTC and UT1,and provide an effective way for the further research of HF time signal modulation technology based on spread spectrum system.