单工无线呼叫系统探析

本设计使用模拟调频技术,在20MHz-30MHz频段上实现了话筒输入和线路输入语音信号的小功率远距离单工发送和接收.数据通信采用FSK调制方式,主、从机可实现智能控制通信,可连接多达236个从站,构成一点对多点的单工无线呼叫系统.从站号码可任意改变,主站可拨号选呼和对全部从站群呼,在语音通信同时可传送数据信息,使用液晶显示英文和汉字短信及站号信息,系统发射功率小于20mW,发射距离大于3m.     

单工无线发射系统的设计

设计了一种单工无线发射系统,详细介绍了系统的总体设计思路、硬件设计、抗干扰措施以及软件实现,具有通信距离远、抗干扰能力强的特点。实现了点对点、点对多点的无线呼叫、无线通话及点对点短信发送乃至点对多点的短信群发功能。     

无线病房呼叫系统设计与实现

为解决传统有线病房呼叫系统布线复杂、维修不便且明线不雅观等问题,设计了一种具有无线通信功能的病房呼叫系统。系统以单片机为核心,采用无线收发模块NRF2401和语音模块YY01,实现了病患与医务人员之间信息传输与反馈的功能,同时可将呼叫信息存储在监控计算机上,以便于信息管理。结果表明,系统配置灵活、功能可扩展、价格低廉,具有良好的可操作性。     

FFSK短信接收机的设计

本设计利用TK868G信道机和单片机做一个单工无线短信接收机,利用电脑串口显示汉字。设计的短信接收机可以通过串口接收PC机f发送的命令来调节各项指标,并且伴有指示灯显示。     

利用教育技术提供英语语言输入环境

校园无线听音系统方式 我们坚持在课堂上用英语组织教学,用英语讲解教学内容,尽量做到用英语教英语.在课外,充分利用校园无线听音系统为学生提供良好的英语语言输入环境.我校于1999年购置了3套校园无线听音系统,包括3个不同频率的发射机和学生人手一个的外语学习机(耳机).高中3个年级各备1套.     

911在行动

美国国家紧急数字协会的统计表明,美国每年的移动电话911呼叫超过5000万。但是,与可追踪的911陆地固定电话呼叫不同,无线呼叫并没有为紧急呼叫中心的操作员提供相关位置的信息,这使得紧急援助人员很难快速作出反应。为了避免此类延误,FCC启动了一项计划,该计划要求到2005年无线运营商(CARRIER)必须为紧急呼叫中心提供呼叫者的地理坐标、回呼号码以及接收到呼叫的天线或者塔的方位信息。专家估计,美国6000多家紧急呼叫中心要更新适用于无线运营商所使用的两种定位方法——手机支持的全球定位系统和基于网络的塔定位——所需要的技术恐怕…     

基于脑机接口技术的病房呼叫系统研究

针对有肢体障碍但大脑思维正常的患者,特别是重症患者使用病房呼叫系统不便的问题,提出了一种基于脑机接口技术的病房呼叫系统.该系统通过提取被试的脑电信号并进行处理来实现对病房呼叫系统按键开关的控制,当陪护人员不在病房时,一旦出现紧急情况,患者可以通过大脑想象手的运动来控制呼叫系统,达到自救目的.     

基于ZigBee技术的老年求助呼叫系统的设计

设计一种基于ZigBee技术的老年无线求助呼叫系统。利用美国TI公司的CC2530芯片完成系统中协调器、呼叫器和应答器的硬件设计,软件设计采用TI的Z-stack协议栈及IAR开发工具,在ZigBee协议的基础上完成各模块上的应用程序设计。     

多输入多输出无线光通信系统中的自适应调制技术（英文）

在基于强度调制、直接检测的多输入多输出无线光通信系统中,为了保证发射信号非负特性,提出一种基于直流偏置的自适应调制技术,并且利用奇异值分解将多输入多输出信道转换为并行信道.此外,提出一种基于QR分解、逐次干扰消除的自适应调制技术.在目标误比特率性能条件下,利用QR分解、逐次干扰消除的特性将多输入多输出信道等效为并行信道.根据最大化可达速率的优化目标,最优地给各个子信道分配功率.仿真结果表明所提出的2种自适应调制方法在保证误比特率性能和平均发射光功率恒定的前提下,有效地提高了系统的传输速率.这2种自适应调制技术在利用多输入多输出技术空分复用增益的同时,进一步提高了无线光通信系统的频谱利用率.     

基于MIMO-OFDM的无线通信系统在煤炭矿井中的应用

我国是世界上煤炭开采大国,由于煤炭开采环境的特殊性,矿井下的无线通信环境与地面的无线通信环境相差甚远,若直接将用于广阔空间的无线通信技术应用到煤炭矿井中会产生无线信号的多径衰落等不可预期的问题,严重影响矿井下的无线通信质量.本文首先从理论上分析了煤炭矿井中多径无线信道的复杂性,并采用瑞利多径信道模型对其进行仿真建模.采用无线通信中多输入多输出技术(MIMO)和正交频分复用技术(OFDM),设计了一套基于MIMO-OFDM的矿井无线通信系统,以减少多径衰落现象对无线信号的消极影响.最后通过MATLAB软件对该系统进行仿真分析,实验结果证明本系统具有抗多径衰减的功能.     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.     

团图为数的图中的闭团贯数

Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F.     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

Social and Cultural Influence on Word Meaning

Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language.     

汉字倒说

汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.