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模拟移动电话“大哥大”在我国已风行多年,1995年以来,性能更为优越的数字移动电话“全球通”在我国又崭露头角,本文就“全球通”的制式网号,加密方式,服务功能主拨打方式等,进行了综合阐述。 相似文献
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我国的全球通数字移动电话用户日前可以使用中国电信、中国联通和吉通三家公司的试验IP业务拨打IP电话,这将为全球通数字移动电话用户提供更多的资费选择权利和更优质的服务。全球通移动电话用户可以接拨打当地普通市话方式,拨打相应IP电话接人号,按IP电话卡使用操作说明使用业务。移动网对移动用户拨户拨打IP电话按拨打当地普通市话收取通话费。移动电话计费系统从IP电话系统播放提示音开始计费,无论电话是否接通,从用户听到IP系统提示音即开始计取移动电话通话费。我国“全球通”可以拨打IP电话@陈金岭 相似文献
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<正> “全球通”是指GSM全球数字移动电话系统。GSM是全球数宇移动通信系统的缩写。GSM的最大特点是容易实现国内和国际漫游。持有全球通数字移动电话的用户可以携带着自己的手机到外地甚至外国打电话。目前中国电信的“全球通”网络已发展成为29个省、市、自治区联网全自动漫游的数字移动通信网络。持有全球通数字移动电话的用户可以携带着自己的手机到这些具有全自动漫游的数字移动通信网络的地区使用;持有全球通国际呼叫功能手机的用户,携带手机到达与我国联网的国家或地区后,只需打开手机电源,自动扫网到出现对方国家(地区)网络代码,经用户确认后,即可随意在当地使用中国电信的“全球通”手机了。可见,使用“全球通”手机是非常方便的。那么使用 相似文献
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“全球通”GSM数字通信系统综述杨清爽“全球通”是中国邮电GSM数字式移动电话系统的别称,它是国际上90年代广泛使用的最先进的通信系统,“全球通”采用GSM制式,GSM是!987年欧共体将欧洲开发的八种数字蜂窝系统制式统一的泛欧制式。目前.我国各省已... 相似文献
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随着新世纪信息时代的到来,手机将不再是简单的通话工具,它除了为人们提供高清晰的通话质量之外,更可以为人们提供“移动上网与传真”、“中文短信息”、“全球通信息广播”、“掌上可视移动电话”等各种新的信息功能。移动上网与传真当你需要用“全球通”移动上网时,应配有以下几种设备:“全球通”数字手机、由手机供应商提供的专用数据传真 相似文献
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80年代,许多具有革命性意义的电子产品为芯片制造商提供了新的发展机遇。进入90年代以后,越来越多的数字化产品的面市加速了整机便携性的提高。本文以蜂窝电话为例阐述了微电子技术在此进程中所起的重要作用。 相似文献
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《Spectrum, IEEE》2000,37(8):35-41
Proponents of personal digital assistants (PDA) say that it will be these hand-held units that tie the on-the-go executive of the future to the Internet. However, looking just as strong is the other big contender for providing wireless Internet access-the next generation cell phone. This article discusses the capabilities and drawbacks of the latest generation of PDAs using the Bluetooth and Wireless Application Protocol networking technologies. The article also discusses the latest cellular phone technology performing similar functions to PDAs. The cost of connecting a PDA to the Internet is also discussed 相似文献
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Taeyoung Yang Davis W. Stutzman W. Minh-Chau Huynh 《Antennas and Propagation Magazine, IEEE》2008,50(3):51-65
With the introduction of digital cellular phones, hearing-aid users have experienced a severe buzzing noise caused by the interaction between digital cellular phones and hearing aids. The cellular-phone industry, the hearing-aid industry, and consumers have been seeking a solution for the interference issue. Efforts reported in the literature have focused on measurements, modeling, and evaluation of interference and RF emission, but not on methods to solve the problem. In this paper, we focus on the causes of the interference and an understanding of the problem. We also present a method to reduce near-field electromagnetic energy around a cellular phone, mitigating the interference between cellular phones and hearing aids. The theoretical investigation of both the radiation mechanisms and fundamental limits on antennas suggested that a low-g antenna, such as an ultra-wideband antenna, could reduce the near-field intensity. Simulations and measurements were performed at 900 and 1880 MHz, using both low- and high-Q test antennas mounted on a mock cellular phone. The results showed that the peak electric and magnetic near-field strengths of the low-g test antenna were lower than those of a high-Q test antenna by at least 5 dBV/m and 4 dBA/m, respectively. The improvement in the near-field performance for the low-g antenna was without any sacrifice in far-field performance. Furthermore, in the presence of a human head, the simulation results showed that the radiation efficiency of the low-Q test antenna was better than that of the high-Q test antenna. 相似文献
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数字移动通信体制的新动向—扩频码分多址(SS/CDMA) 总被引:3,自引:0,他引:3
本文主要讨论数字移动通信中扩频码分多址技术,介绍了国外关于CDMA数字移动通信研究的动态,阐明了CDMA体制的优越之处,分析了CDMA的关键技术,并就我国数字移动通信体制提出建议。 相似文献
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Explosive growth of the cellular phone industry in Malaysia has been witnessed in the 1990s. Eight nationwide cellular phone operators with different technology bases exist in a single market. This article provides an overview of the telecommunications industry, especially the cellular phone sector, and also the activities on IMT-2000 in Malaysia 相似文献
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介绍了模拟和数字通信回路兼收的市话电缆内线对间的串音特性,日本NTT公司对市话电缆承载数字传输能力的调查测试情况,并作了分析。 相似文献
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本文采用OMA DRM标准,以PKI安全体系为基础,采用HTTP和ROAP作为传输协议,设计出一个在手机上使用的,基于智能卡的数字版权保护系统。用户通过使用该系统,可以在手机上有偿地使用各种数字资源,随时随地享受网络带来的方便与快捷。 相似文献
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The design and experimental results of a 2.7 V 50 MHz switched-capacitor DS modulator in a 0.35 μm BiCMOS process are presented. The circuit is targeted for the IF section of a radio receiver in a GSM cellular phone. It combines frequency downconversion with analogue to digital conversion by directly sampling an input signal from an IF of 50 MHz. The measured peak signal-to-noise ratio for a 100 kHz bandwidth is 81 dB with a 53 MHz blocking signal and the measured IIP3 for IF input is +36.9 dBV 相似文献
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本文提出一种基于二维码的网络流媒体播放系统.通过手机摄像头读取二维码信息,直接连接流媒体信息进行播放,该系统方便实用,具有较高的应用价值. 相似文献