基带成形滤波器的FPGA实现

针对数字化基带成形滤波的信号处理特点，将截短的基带波形进行二维分解，得到成形滤波器的多相结构。通过对多相结构的分析，给出了一种较为精简实用的基于滤波器系数查询表模式的FPGA实现结构，该结构具有实现简单、占用资源少等特点。仿真结果表明，该结构完全可以达到实际应用的要求。     

Public perception of scientific uncertainty in relation to food hazards

The research reported here aims to understand how people react to statements expressing risk uncertainty information in the context of a commonly experienced potential hazard, food related risks. Public perception of seriousness of risk for themselves, and for other people was examined for different types of uncertainty, for each of five different food hazards. The results indicated that participants responded to the different types of uncertainty in a uniform way, suggesting that perception of risk associated with uncertainty is not affected by the 'type' of uncertainty. The results further indicated that the seriousness of risk, in the presence of statements of uncertainty, was perceived to be greater for pesticides and genetic modification compared to BSE, high fat diets and Salmonella . It was argued that this could be due to the perceptions of low personal control, and high societal responsibility to protect people and societal control over exposure to the potential risks of pesticides and genetic modification. Under circumstances where people feel they have little personal control over their exposure to a particular hazard, and those social institutions that are perceived to be in control of protecting the public indicate that there is uncertainty associated with risk estimates, the hazard may appear to be 'out of control', which is associated with a perception of serious risk.     

可编程直接序列扩频通信系统的数字化实现

本文讨论了利用ASIC芯片和CPU实现直接序列扩频系统数字化的方法，阐述了各部分电路的设计思路，给出了系统总体框图及实验系统的信号波形。     

Concerning trust and information

Communication and the associated information exchanges are key drivers of the development of relationships and of the trust embedded within them. This paper considers the development of business relationships in terms of the continuing co-evolution of trust and information exchange and the issues associated with researching these processes. The interconnections of trust and information exchange are examined in a survey of business relationships involving information exchange (n = 355). Analysis of variance shows few, if any, of the aspects of the standard conceptualizations of information exchange are associated with increased levels of trust. It is information exchange norms that have the greatest (positive) association with the level of trust. These norms emerge as part of the long term co-production of the relationship itself. This has important managerial implications. We conclude there are few managerial actions involving managing communication that can “manufacture” trust and improve or develop relationships in the short term. The paper concludes with a discussion of alternative ways of envisaging communication and relationship management and the nature and future of research into the evolution of business relationships.     

阴影环境下陆地移动卫星信道的模型研究

陆地移动卫星信道通常用全阴影模型和部分阴影模型进行分析。本文利用全阴影模型的研究结论，就实际陆地移动卫星信道部分阴影模型的仿真问题，拟合了模型参数与卫星仰角之间的关系。通过统计特性的数值计算，验证了部分阴影模型与全阴影模型的一致性。     

Persistence and Change at the Top of the IT Sector

We use the DATAMATION index of the top 50 domestic IT companies (1975–1995) to track persistence and change at the top of the sector. The trends that we uncover are increasing instability, rejuvenation (declining average age of entrants coupled with increasing average age of quitters), democratization (diminishing revenue inequality at the top) and growing supply‐side intertwining of sub‐sectors and industries within IT due to diversification by long‐term survivors.     

一种利用短时DFT分析实现全数字2DPSK接收机解调的新算法

本文提出了一种简单而实用的利用短时DFT（ST-DFT）分析实现全数字2DPSK接收机的解调算法。该算法对由多谱勒效应引起的时变频率漂移具有鲁棒性。由于该算法是通过检测在载频处的瞬时能量谱的跳变来实现2DPSK信号的解调，所以该算法不需要进行专门的载波相位恢复、符号定时，且具有较好的抗噪性能，实现起来简单。     

直接数字频率合成技术实现调频

本文阐述了ＤＤＳ的基本原理，语音信号的采样，如何用ＤＤＳ实现调频，并提供了试验结果。     

Research and development policy in the USA: Implications for satellite communications

Research and development in fields as diverse as microelectronics and space vehicles have profoundly affected the technologies of information transmission, as well as the way in which government regulates the communications and information service industries. This article focuses on R&D policy in the USA, drawing from 1984 OTA reports. The article focuses briefly on industry and universities and at greater length on government actions and policies, indicating possible implications for communication satellites.     

山区超短波无线电通信链路的设计

叙述了山区超短波无线电通信电路设计的有关技术问题，给出了山峰绕射模式的传输损耗计算方法、绕射位置判断的方法及计算程序流程图，最后通过实例说明此方法的计算精度。