CDMA2000系统海域覆盖浅析

随着经济的发展,海域通信日益增多,沿海覆盖也是日益受到重视。从影响海域覆盖的因素、覆盖规划原则、天线选择、覆盖方案等方面介绍了cDMA无线网络的海域覆盖。     

CDMA近海海域覆盖解决方案

简述了近海海域覆盖的特点和必要性,并通过一个海域覆盖案例说明超远覆盖基站是一种经济实用的解决方式.     

WCDMA海域超远覆盖解决策略及其应用

结合中国联通漳州分公司2010年5月开展的WCDMA海域覆盖专项优化实例，从制约WCDMA超远距离覆盖的几个重要因素入手，提出了相应的解决方案，并通过应用效果分析进行了经验总结。     

CDMA网络海域覆盖分析研究

海域覆盖具有覆盖距离远的特点.通过对江苏海域CDMA网络覆盖仿真研究,出了一种海域网络的分层覆盖方法.结合实际网络特点,过网络仿真分析调整实际CDMA网络的工作参数,到指导实际网络的海域覆盖方法,用于网络的优化.     

CDMA网络海域覆盖工程方案探讨

文章简述在近海海域实施无线网络覆盖的必要性,通过理论分析、测试数据,结合在北方某市海域网络覆盖工程经验,提出一套工程实施方案以供探讨。     

CDMA网络海域覆盖工程方案探讨

简述在近海海域实施无线网络覆盖的必要性,通过理论分析、测试数据,结合笔者在北方某市海域网络覆盖工程经验,提出一套工程实施方案以供探讨。     

加装多层天线实现逻辑同扇区、同频率、分层覆盖

利用现有资源扫除“近站区”盲区、同时对农村或海域地区进行大范围的有效覆盖，以及当有WCDMA 3G用户（如384K）在线时如何避免其它用户的掉网。     

无线基站用于海域覆盖时出现的问题及其解决方法

首先提出了用GSM900无线基站在做近海海域覆盖时会出现的一些问题，并阐述了其原因：随后给出了处理这些问题的解决方案，最后提供了一个在实际工程中对某海域覆盖型基站的测试实例。     

CDMA网络海域覆盖分析研究

海域覆盖具有覆盖距离远、受海面情况影响大的特点。具有重要的经济和社会意义。通过对某省海域CDMA（CodeDivisionMultipleAccess．码分多址）网络实际信号的海测数据分析,结合各种情况下海域覆盖仿真分析研究,提出了一种海域网络的分层覆盖方法。通过规划合适的远近海域区域,结合远近海区域CDMA信号覆盖特点,在远近海采用最优化的网络组合,达到远海覆盖尽量远,近海完全覆盖。同时分析并调整实际CDMA网络的工参,得到指导实际网络的海域覆盖方法,应用于网络的建设和优化。     

理想情况下海域网络覆盖分析

海域覆盖具有覆盖距离远、受海面情况影响大的特点。通过对某省海域CDMA(码分多址)网络覆盖仿真研究,文章提出了一种海域网络的分层覆盖方法,通过规划合适的远近海域区域,结合远近海区域CDMA信号覆盖特点,在远近海采用最优化的网络组合,达到远海覆盖尽量远、近海完全覆盖。同时分析并调整实际CDMA网络的工程参数,得到指导实际网络的海域覆盖方法,应用于网络的优化。     

GPS海面散射信号探测技术研究

该文简述了利用GPS散射信号进行微波遥感的背景和优点,并从GPS海面散射信号极化特性、信号波动情况、波程差引起散射信号相对直射信号的码延迟以及由于海面粗糙度引起的散射信号相关功率扩散几个方面详细分析了海面散射GPS信号检测技术。给出了自行研制的延迟映射接收机的工作原理, 在天津近海进行了首次搭载飞行试验,数据分析结果与理论分析符合。     

智能化海豚动力电源设计

为解决对海洋探测和海洋环境污染实时监测的电源问题,通过把微型水力发电机系于海豚身上,随着海豚运动时海水的反作用力驱动水力机转动发电,经整流滤波稳压后给锂电池板充电,从而海洋探测和海洋环境污染监测时可以使仪器获得稳定的电源。利用压力传感器、单片机、电磁控制和无线传输网络,增加该智能化海豚动力电源的可靠性和实用性,实现对仪器的回收和避免仪器对海洋环境的污染。     

A fading reduction method for maritime satellite communications

A maritime satellite communication system has been established mainly for large vessels. In the near future it will be expected to service not only large vessels but also small ones. Studies on reducing the fading of the received signals have become very important because a compact antenna designed to be mounted on small vessels has a broad beamwidth which can be greatly influenced by reflected waves from the sea surface. A simple method and antenna equipment which can reduce the fading are proposed and, further, the effects by experiments are confirmed.     

Polarimetric measurements of sea surface brightness temperaturesusing an aircraft K-band radiometer

Presents the first experimental evidence that the polarimetric brightness temperatures of sea surfaces are sensitive to ocean wind direction in the incidence angle range of 30 to 50°. The experimental data were collected by a K-band (19.35 GHz) polarimetric wind radiometer (WINDRAD) mounted on the NASA DC-8 aircraft. A set of aircraft radiometer flights was successfully completed in November 1993. The authors performed circle flights over National Data Buoy Center (NDBC) moored buoys deployed off the northern California coast, which provided ocean wind measurements. The results indicate that passive polarimetric radiometry has a strong potential for global ocean wind speed and direction measurements from space     

Effect of realistic sea surface movements in achieving full‐view coverage camera sensor network

In stationary camera sensor networks (CSNs), when the deployment characteristics and sensing models are defined, the coverage can be deduced and remain unchanged over time. However, in the maritime environment, the rough and random sea condition can move CSN from the initial location. We envisage that camera sensors are mounted on quasi‐mobile platforms such as buoys. Hence, it is important to understand the effect of realistic sea surface movements in achieving full‐view coverage because in full‐view coverage, target's facing direction is taken into account to judge whether a target is guaranteed to be captured because image shot at the frontal viewpoint of a given target considerably increases the possibility to detect and recognize the target. To accurately emulate the maritime environment, the movement of the buoy, which is attached with a cable that is nailed at the sea floor, has been characterized based on the sea wave that is created by the wind, and it is limited by the cable. The average percentage of full‐view coverage has been evaluated based on different parameters such as equilateral triangle grid length, sensing radius of camera, wind speed and wave height. Furthermore, a method to improve the target detection and recognition has been proposed in the presence of poor link quality using cooperative transmission with low power consumption. In some parameter scenario, the cooperative transmission method has achieved around 70% improvement in the average percentage of full‐view coverage of a given target and total reduction of around 13% for the total transmission power P_Total(Q). Copyright © 2015 John Wiley & Sons, Ltd.     

A Shipborne Antenna for Maritime Satellite Communications

From a cost effectiveness point of view, the shipborne antenna is usually considered the most critical component in a shipborne terminal for maritime satellite communications (MARSAT). For possible use in such a system, a high gain autotrack antenna has been developed. The antenna utilizes a combined electronical and mechanical beam steering realized with two planar phased arrays mounted on a mechanical axis. The antenna system is designed for unmanned operation, utilizing an automatic search-and-track mode. After acquisition of a beacon signal from the satellite, a monopulse track mode keeps the antenna pointing position locked, to the direction of incident beacon signal, irrespective of the motions of the ship. Attention has been paid to multipath effects that may occur, in particular reflections from the surface of the sea. This paper is concerned with the design background and the development of the antenna system.     

一种新体制的高频地波雷达设计与实现

传统高频地波雷达接收机与天线阵列由长电缆连接,存在成本高、架设难、不易维护等问题。本文提出了一种新体制的高频地波雷达系统,该系统将多通道接收机分为多个装配在接收机天线附近的独立的单通道接收单元,接收单元与天线之间采用短电缆连接模式,各个接收单元之间通过GPS/北斗进行时钟同步,通过无线方式进行参数配置和数据传输。在完成单通道接收单元设计与实现后,通过闭环实验和海边现场实验对整个新系统进行了检测,得到了稳定的海洋回波,证明了新体制雷达系统的可行性。     

劈刀安装长度对引线键合强度影响的实验研究

在超声引线键合中引线键合质量受到多种因素的影响。该文通过实验,观察了超声引线键合过程中不同劈刀安装长度对引线键合质量形成的影响,同时对引线键合过程中换能系统电流、电压及功率进行了分析,发现不同劈刀安装长度会导致引线键合质量、电流及功率较为明显的变化。该实验的结果可为实际引线键合中劈刀安装长度的选择提供参考。     

Hardware-In-the-Loop test rig for the ISWEC wave energy system

The Hardware-In-the-Loop (HIL) simulation is a powerful mean to reduce costs in the design and manufacturing process of an engineering system. HIL techniques allow to use real components inside a simulation of a mathematical model. In this work such techniques are used on the ISWEC wave energy system. ISWEC (Inertial Sea Wave Energy Converter) converts sea waves energy to electric energy by means of the gyroscopic effects produced by a spinning flywheel. The peculiarity of the system lays in the fact that all the moving parts needed to produce energy are sealed inside a hull and therefore protected from the aggressive ocean climate. During the research process on the ISWEC, the gyroscope and the electric generator have been manufactured and mounted on a test rig able to simulate the wave actions on the hull of ISWEC. Those real parts of the system have been replaced inside the full mathematical model of ISWEC. Such HIL system is validated against real wave tank tests carried out at the INSEAN in Rome. The HIL simulations proved to reproduce the real behavior in water waves of ISWEC with errors as small as the 10%.     

透射电镜数字成像系列装置的设计

目的：探讨不同类型透射电镜数字成像装置设计方案,以实现更好性能.方法：分析现有不同类型透射电镜数字成像装置产品或设计的结构特征及其存在的主要问题,构思新的解决方案.结果：提出了包括侧装透镜、侧装光纤、底装透镜和底装光纤耦合型四种基本类型透射电镜数字成像装置新的设计方案,研制了底装大视野透镜耦合型样机并用于实际工作.结论：新的底装透镜耦合型成像装置结构独特,特别适合需要大视野的生命科学和医学等领域.