高频电压测量中检波效率的线性化处理

通过对高频检波器的分析,论述高频检波效率的非线性特性及高频电压测量中检波的线性化处理问题,提出高频检波效率的数学模型,指出解决高频电压较精确测量的途径。

门限检测电路的实用化设计

门限检测电路是对整机系统及其重要单元电路进行故障自动检测和处理的关键部件。在对门限检测电路工作原理进行了简单分析的基础上,提出了门限检测电路的一些设计要点。按照这些设计要点,讨论了对复杂多变的射频、微波信号进行处理的基本原则,详细分析了影响检波器检波效率的各种原因,简述了在当前高频、微波通讯系统中获得广泛应用的门限检测电路的实用化设计方法。

关于6J1的电路改进和安装调试时几个必须注意的问题——教学随笔

美音牌6J1晶体管收音机是我校为学生实验而采购的机型之一。本机系便携式六晶体管中波段调幅广播收音机,电路由硅、锗管混合组成,变频、中放基极偏流采用稳压电路装置供给,降压性能良好,具有较高的灵敏度和选择性（灵敏度不劣于1 mv/m、选择性≥20dB）,造型新颖,美观大方,音质优美,结构简单,便于初学者学习、安装和调试.但是笔者从理论和实验两方面发现该机在电路设计方面的一点不足之处,以致影响了整机性能和技术指标。如图（1）所示,电阻 R7、R8、R9和电容 C8组成自动增益控制电路,电阻 R7又和 R4、R8、R9组成中放管 G2的偏置电路,同时给检波二级管

Trading volume and returns relationship in SET50 index futures market

This study investigates the relationship between trading volume and returns in SET50 index Futures market in the period from April 2006 to December 2008 using 653 observations. From previous studies, we include three methodologies namely the GARCH model, the Generalized Method of Moments （GMM） to estimate systems of equations and the Granger causality test to investigate the relationship more thoroughly. In addition, we introduce the lagged volume as a new explanatory variable in the GARCH model. Overall, the results show the significant contemporaneous and dynamic relationships between trading volume and returns volatility which support the sequential information arrival hypothesis and imply some degree of market inefficiency. The results from this study also show that past information of trading volume can be used to improve the prediction of price volatility. Therefore, regulators and traders could include past information of trading volume of SET50 index futures in tracking and monitoring the market volatility level and the investment risk in order to make a timely decision.