采用卫星QPSK调制方式在高斯信道中传输地震数据的性能分析

为了获得卫星通信系统传输地震数据的误码率,借助MATLAB软件仿真地震数据在高斯信道中的传输过程,建立卫星调制方式模型和高斯信道模型,使地震数据经过所建立的模型处理后,得到不同信噪比情况下的误码率。并分析卫星通信系统使用QPSK调制方式调制、传输地震数据对信号传送的影响。最后采用蒙特卡罗法仿真获取准确误码率曲线,为使用...     

厦门市地震应急指挥系统建设及思考

介绍厦门市地震应急指挥系统在视频图像、应急通信、应急指挥软件等方面的建设,并对系统中存在的不足进行讨论,对厦门市今后的地震应急指挥建设做进一步思考.     

基于WINSOCK的网络实时通信系统的实现

介召了在VB6.0环境下,运用Winsock控件和TCP协议进行实时通信编程、TCP协议连接过程、信息加密与解密和软件设计部分介绍等.     

Research and Application of Cosmic-ray Fast Neutron Method to Measure Soil Moisture in the Field

It is very difficult to measure large region soil moisture. In recent years, measurement of surface soil moisture by the cosmic ray fast neutron probe has gradually attracted more attention. By this passive, non-invasive and intermediate scale measurement, soil moisture at a horizontal scale of around 300 m can be observed, which makes this method available to fill the gap between little scale of traditional point measurement and large scale of remote sensing in the measurement of soil moisture. In this paper, Cosmic-ray Soil Moisture Observing System (COSMOS) and Wireless Sensor Network (WSN) were used to observe field soil moisture in Zhangye Oasis. The results of the COSMOS soil moisture well reflected the variation trend of soil moisture at the field scale. There were some regular changes with the cosmic ray soil moisture during the irrigation period. Combined with irrigation data in cosmic-ray probe footprint, a bimodal change was showed in the cosmic-ray soil moisture figure during irrigation period. This was because that the order of irrigation of the three communities was different in cosmic-ray probe footprint. WSN data were used to validate this result and we found that root-mean-square error between cosmic-ray soil moisture and SoilNET average soil moisture was very large during irrigation periods because of the impact of cosmic-ray measurement theory. While root-mean-square error would decrease from 0.037 m³/m³ to 0.028 m³/m³ after we eliminated the data in irrigation period. So COSMOS can be used to measure field soil moisture under high heterogeneity condition and provide truly ground data for the validation of remote sensing     

声学地层剖面野外数据采集几个关键问题的解决

针对目前国内几款通用的声学地层剖面野外数据采集商业软件,分析探讨了国外软件在数据采集与存储中存在的几个关键缺陷,如GPS滞后、强能量反射同相轴相位与极性改变、深水数据采集存储等严重缺陷。为解决上述缺陷,作者以ChirpⅢ硬件系统为基础,分析国外商业软件缺陷产生的原因,并通过自主研发,提出了解决这些缺陷的方法。经野外实际工作测试,证实了文中所提方法的正确性与可靠性。     

Low complexity adaptive equalizers for underwater acoustic communications

Interference signals due to scattering from surface and reflecting from bottom is one of the most important problems of reliable communications in shallow water channels. To solve this problem, one of the best suggested ways is to use adaptive equalizers. Convergence rate and misadjustment error in adaptive algorithms play important roles in adaptive equalizer performance. In this paper, affine projection algorithm （APA）, selective regressor APA（SR-APA）, family of selective partial update （SPU） algorithms, family of set-membership （SM） algorithms and selective partial update selective regressor APA （SPU-SR-APA） are compared with conventional algorithms such as the least mean square （LMS） in underwater acoustic communications. We apply experimental data from the Strait of Hormuz for demonstrating the efficiency of the proposed methods over shallow water channel. We observe that the values of the steady-state mean square error （MSE） of SR-APA, SPU-APA0 SPU-normalized least mean square （SPU-NLMS）, SPU-SR-APA0 SM-APA and SM-NLMS algorithms decrease in comparison with the LMS algorithm. Also these algorithms have better convergence rates than LMS type algorithm.     

基于测向测时差云闪定位精度分析及布局优化

针对多站雷电定位系统中的云闪定位问题,建立4站云闪辐射源定位模型。根据探测站探测的云闪电磁波到达的时间和角度信息,结合无源定位理论中的测向测时差定位法,给出云闪定位计算方法和精度评定。利用Maltab,仿真探测站不同布站方式下的云闪定位误差分布情况。通过对比研究,得出最优布站形式,并对最优布站形式的精度影响因素进行分析。结果表明,布站形式、基线长度、探测站高度等因素均可对云闪定位精度产生影响。     

Social participation and social capital with equity and efficiency: An approach from central-place theory

A great deal of attention has been paid to the efficiency of the analysis of sustainable urban and regional growth. This includes social participation and social capital, which require a consideration of equity. In this paper, an approach from central-place theory for sustainable urban and regional growth is examined, taking into consideration relevant variables such as ageing, social interaction and accessibility. A lack of consideration of equity could cause several social exclusion problems, and these problems could develop into spatial consumer exclusion. Solutions for these problems would not only improve equity but also efficiency, and the outcome would addresses the necessity of an alternative spatial formation based on a wider-regional rural central-place system according to given economic, social and spatial configurations.     

无线数字测图程序设计中的关键技术

在数字化测图软件中,对数据进行属性拓展和添加连接关系并对图面进行美观,是软件的主体机构,但如何将野外碎步点实时展绘到测图软件里形成空间属性数据,是关系到成图质量的关键.本文就如何在数字测图的过程中通过无线传输技术通讯全站仪,将全站仪传回的数据进行分析、验证,实时将所测点位展绘到测图软件中的关键技术进行讨论.     

北斗二代系统在测试场超视距通信指挥中的应用

为解决测试场试验中区域跨度大、精度要求高、目标批数多、超视距数据实时传输困难等难题,提出了利用北斗二代系统短报文通信功能进行超视距简短通信指挥。从通信技术指标、工作方式等方面介绍了北斗二代系统的通信技术特点,对北斗二代系统短报文通信与测试场传统通信方式进行了比较,最后,重点介绍了应用北斗二代系统在测试场进行超视距通信的设计方案,该方案在试验中得到了实际应用。