共查询到19条相似文献，搜索用时 125 毫秒
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无线数字遥测地震台网的信道测试 总被引：1，自引：0，他引：1
在无线数字遥测地震台网中,信道测试是台网传输的关键环节,关系到台网的运行率和地震信号的可用率,甚至整个台网建设的成败。信道测试有3方面的内容:中继站背景场强测试、子台信道储备测试和信道误码测试。经测试后得到各种参数柱状图,以此判断每个台站的信道质量情况,及时调整台网信道传输的设计方案,确保成功建成无线数字遥测地震台网。 相似文献
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介绍了超短波、微波扩频及卫星技术在数字遥测地震台网中的应用领域及优势,根据各频段无线电波的传播特点和数字遥测台及中继站数据复分复接技术要求,阐述了无线技术在数字遥测地震观测系统中实现的方式和步骤,并叙述了超短波及无线扩频技术在合肥数字遥测地震台网的应用以及在实施过程中需注意的几个技术环节. 相似文献
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Canopy宽带接入系统在龙滩水电工程数字遥测地震台网信道优化设计中的应用 总被引：1，自引：1，他引：1
采用Canopy无线宽带接入系统,优化龙滩水电站数字遥测地震台网信道建设方案.通过构建VPN网络,利用公共互联网资源,实现对边远山区水库遥测地震台站现场图像监控、设备远程管理等,提高台网维护工作效率. 相似文献
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余凤仙 《地震地磁观测与研究》1987,(2)
本文对苏南无线遥测地震台网信道特性存在的问题,提出了改进意见.对768发信机前置放大器积分电路参数进行了调整,从而改善了信道特性,在地震观测中这一改进是有成效的. 相似文献
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新疆乌鲁木齐区域数字遥测地震台网(以下简称区域台网)是在模拟遥测地震台网的基础上改造、扩建而成的。区域台网由数字汇集中心、4个中继站、12个遥测子台和9个准实时远程子台组成。中国地震局港震公司提供地震计、数据采集器和应用软件，新疆地震局与厂家共同研制无线同步传输设备。区域台网的技术系统采用了先进的数字地震观测技术，具有宽频带、大动态、高精度、高分辨率的特点，以无线实时传输台网为主，远程扩展子台为辅，构成了全国最大的省级台网。2001年4月22日，乌鲁木齐区域数字遥测地震台网通过了中国地震局专家组验收。 相似文献
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王翠芳 《地震地磁观测与研究》2003,24(5):112-115
引言 攀枝花地区被多个强震潜在震源区围限,是四川省地震多发区之一。为了快速准确地测定攀枝花及邻区可能发生的地震,在市政府的支持下,攀枝花数字遥测地震台网已经投入建设。 众所周知,一个地震台网的建成分为总体设计、野外勘选和安装调试3个阶段。其中野外勘选阶段又分为台基测试和无线信道测试(不包括有线传输)。无线信道测试的主要目的是摸清信道的主要状况,包括增益储备、路由中的阻挡情况,传输方向以及雷电袭击等情况,这将为今后设备选型和工作频段的选择提供强有力的设计依据。在信道测试中主要用信道误码来表征信道的主要状况。具… 相似文献
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The effects of the solar eclipse of March 29, 2006, in the signals of ULF radio stations, in the intensity of regular radio noise at frequencies of 0.3–10 kHz, and in the number of atmospherics received in Yakutsk mostly from the west have been considered. The observations were performed using a multichannel parallel analyzer-recorder (11 channels in the frequency band 0.47–8.7 kHz), one-point lightning direction and range finder (0.3–100 kHz), narrow-sector radio noise direction-finder (0.3–10 kHz), recorder of signals from VLF radio stations, and broadband radio noise recorder (0.3–100 kHz). A GPS clock was used to synchronize a recorder of signals from VLF radio stations. The effect was observed in radio signals, radio noise, and number of atmospherics from the direction 270° ± 20° counted off clockwise from the north during the last stage of the eclipse (～ 1100–1200 UT), when the lunar shadow approached the line of the nighttime terminator and obscured part of the signal propagation path. The effect was observed as an enhancement of the received signals by a factor of ～1.2, a factor of ～1.4 increase in the number of atmospherics, and a change in the radio station phase values. 相似文献
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我国近年水库地震监测综述 总被引：8，自引：4，他引：4
杨晓源 《地震地磁观测与研究》1999,20(2):3-15
在较完整地收集我国水库诱发地震震例的基础上,回顾了我国水库诱发地震监测的成长进步厍程。本文认为无线遥测组网和计算机实时处理方式是我国近年水库诱发地震监测的主流,数字化则是其发展方向。作者提出了按地震监测系统的主要特征。对水库地震监测台网分类划代方法,将我国已客在建的水库地震监测台网划分四代。本文较详细地介绍了近年建成投测的二滩,大桥、小浪底和李家峡等第三代水库遥测地震台网的基本情况。对正在设计建设 相似文献
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G. P. Chernov V. V. Fomichev Y. Yan B. Tan Ch. Tan Q. Fu 《Geomagnetism and Aeronomy》2017,57(6):738-751
The reason for the occurrence of different elements of the fine structure of solar radio bursts in the decimeter and centimeter wavelength ranges has been determined based on all available data from terrestrial and satellite observations. In some phenomena, fast pulsations, a zebra structre, fiber bursts, and spikes have been observed almost simultaneously. Two phenomena have been selected to show that the pulsations of radio emission are caused by particles accelerated in the magnetic reconnection region and that the zebra structure is excited in a source, such as a magnetic trap for fast particles. The complex combination of unusual fiber bursts, zebra structure, and spikes in the phenomenon on December 1, 2004, is associated with a single source, a magnetic island formed after a coronal mass ejection. 相似文献
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This paper presents improvements to the global D8 (GD8) method for calculating single flow directions in a grid digital elevation model. Flow directions computed from grid digital elevation models serve as the foundation for much of the analysis and modeling of hydrological processes that are driven by topographic gradients. The literature includes both single flow direction methods, where flow goes to only one downslope cell, and multiple flow direction methods that apportion flow among multiple downslope cells. Among single flow direction methods, the standard D8 method, in which the flow direction is set based on the steepest local slope, results in bias on surfaces that do not align with the grid directions. Efforts to address this problem have led to the development of extended methods that account for elevation values further upslope in determining flow directions. We have identified discrepancies in one such method, GD8, and have examined ways to resolve these discrepancies. An improvement to GD8, named iGD8, is presented that allows replacing a reference cell from which path deviations are accumulated and that considers horizontal path deviation rather than global slope as a flow direction criterion. The improved method is found to be effective in resolving the problems encountered with GD8 and to be more efficient than a previously proposed alternative method (least transversal deviation (LTD) based D8, namely D8‐LTD) that uses recursive searching for the largest upstream area when multiple flow paths converge. The proposed improved GD8 method offers the opportunity for improved analysis and modeling of topographically driven hydrological processes by providing better foundational flow directions for these analyses. 相似文献
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Angles of arrival of HF mesosphere radar echoes 总被引：1，自引：0，他引：1
A. N. Karashtin Yu. V. Shlyugaev V. I. Abramov V. V. Bychkov G. P. Komrakov 《Geomagnetism and Aeronomy》2007,47(2):244-250
The distribution of the angles of arrival of mesosphere radio echoes has been obtained and studied. Special attention has been paid to the region of altitudes in the vicinity of the mesopause. It has been indicated that the angle of arrival distribution in this region has a maximum near the direction toward the zenith and is anisotropic. At the same time, the average intensity of radio echoes substantially exceeds the background level for any angles of arrival. 相似文献
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叙述了遥测地震台网联网中使用的有线、无线电VHF和UHF地震信号及数字数据的传递技术原理及其方法。 相似文献
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Large water utilities adopt various levels of automation involving digital computer technology and modern instrumentation that provide the capability of controlling most operations in the water treatment and distribution system. One of the major components of water system automation is telemetering of information to and from a central control centre.Most water utility systems currently use leased telephone lines for telemetry requirement. An alternative approach is microwave telemetry. Concern about recent increases in leased-line tariff rates, the apparent tendency for further increases, and the degree of service provided by local telephone systems led to a study which showed that overall water distribution system telemetry cost can be minimized by adopting a hybrid telemetry system composed of both radio links and telephone links.A need arises to determine the transmission links for which each alternative method is economically more suitable. This paper presents an interactive computer program which performs an economic analysis of the transmission links in a water distribution system to determine the hybrid configuration of radio and leased phone lines that provide the most cost-effective telemetry system. A typical phone tariff structure is presented. The set of input variables can be altered interactively, and the effect of the change on system telemetry cost can be examined, allowing a resolution of a series of ‘what if’ questions of interest to a water utility manager. A case example is presented. 相似文献
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768无线地震遥测设备是为在电信传输地震台网的网点间不易架设明线,或线路容量不足的场合使用而专门设计的,当然,也可用于受大地震破坏的现场.该设备是由一对超短波发射机与接收机构成,采用二次调频.它既可直接与单分向短周期地震计连接传输0.5HZ-25HZ 的地震模拟信号,也可直接与专门设计的多路数字前兆遥测设备配合使用传输0.2HZ-20HZ 的 CHDB4码（相容高密度二进制码）.因而可用来传输地电、地磁、地应力、地倾斜等多种地球物理量.该仪器自1977年7月起先后在北京、上海、天津台网进行了实地传输试验,其后又在昆明地震台网使用了一年多.结果表明,该仪器轻便、灵活、稳定、可靠,有较强的抗干扰性.当天线架设高度足够时,最远传输距离可达115公里. 相似文献