对于圆检测,许多研究人员已经运用参数分解和/或圆的一些几何性质,搞出了霍夫变换的变体以减少计算的复杂性。Yuen等人在1990年的论文中已经对圆的识别的集中霍夫变换的技术进行了比较研究。以参数分解为基础的方法通常是先检测圆心,然后确定半径。这样做的特点的其中之一是圆上一点的方向向量经过圆心(Davies, 1987a; Illingworth and Kittler, 1987). 叶等人在1992年的论文中用到一个性质:圆上两点的切线平行,那么这两点就是圆的直径的两个端点。上述方法需要有对干扰因素十分敏感的边缘等级线的梯度的信息(Davies, 1987b). 干扰因素对边的方向的作用通常要比对边的位置的作用大。不使用边缘方向信息的几种途径包括:陈和Siu(1990)提出了基于水平和垂直弦的中分线的快速椭圆检测法。同样,Ho和陈(1995)提出了一种使用全局几何对称性的快速检测圆的算法,通过水平和垂直对称轴计算出圆心。Sheu等人在1997年的论文中,在整个过程中运用了对称轴的信息来计算所有五个参数。 Goneid等人在1997年的论文中使用一维数组创建了弦的中分线法。Davies(1999)研究了一个用于椭圆的快速精确定位的简单的弦的中垂线法。 Ioannou 等人(1999年)的方法是基于垂径定理。Lei和王(1999)发现了对称轴,继而发现了几对交点是圆心的可选值的正交轴。其缺点是图像中的直线会让对称轴的检测更复杂。
对于圆检测,许多研究人员已经研究出使用改性羟色胺的方法分解参数和/或圆的一些几何性质,以减少复杂性。元朗等。 (1990年)已经进行了几羟色胺为基础的循环寻找技术的比较研究。参数分解为基础的方法通常是先从对检测中心的圆圈,然后确定半径。这些属性之一是正常的一个点上一圆通过圆(戴维斯,1987A的;伊林沃思和Kittler,1987)的中心通行证。业等。 (1992年)所使用的财产上的两个圆的切线平行是圆的直径的端点点。上述方法需要的边缘轮廓对噪声非常敏感(戴维斯,1987年b)梯度信息。关于边缘的方向等信息噪音é€一般大于边缘位置。有没有使用边缘方向信息的几种途径。陈和小(1990)提出了基于快速椭圆检测的水平和垂直平分弦。同样,何和陈(1995)提出了一种快速检测算法界使用一个全局的几何对称性。它计算出来的对称轴和垂直轴对称水平圆心。许等人。 (1997年),用于在整个过程中,信息对称轴计算所有五个参数。 Goneid等。 (1997年)制定的和弦二分法使用一维数组。戴维斯(1999)研究了椭圆形的快速精确定位的简单和弦二分法。约安努等人的方法。 (1999年)已在该行的财产垂直平分一圆的弦穿过其中心的基础。雷和黄(1999)检测,发现对称轴的交点的两个中心是正交轴对候选人。其缺点是图像中的直线可以使检测复杂的对称轴。
五.评议在这封信中,我们已经表明在对半双重WAGN单转播频道的转播做解码时,部分解码无法像全解码那样获得很多信息。我们的分析已经表明使用向前部分解码(PDF)可以提高前向全解码(CDF)的速度,最多可以提高八分之一。我们确定了在四种情景中,CDF速度会逐渐接近PDF的速度。 在本论文中得出PDF和CDF成乘法关系时 ,我们注意到绝对增长可能在高SNR架构中不受限。(我们已经在评议一表明绝对增长的上层范围是不受限制的)。因此在传输速度(和增长百分百相反)的绝对增长比系统复杂度更重要时,是可能在高SNT架构中引发PDF的。 这封信中的结果,为进一步比较这两种针对多址中继信道而调查当网络中有更多中继时比前向全解码计算更为复杂的前向部分解码是否更有利的策略提供了动力。 --真的不好翻译,关系很复杂,希望对你有帮助!!!
如果你处理外文文献只是阅读理解仅供参考的话,一些在线翻译平台都是可以的,比如说谷歌百度有道qtrans,机翻用于理解是不成问题的,但是如果你是想翻译过来用到文章里面的话,还是需要译后处理一下的,如果你自己外文比较好的话完全可以自行加工一下,或者找一些专业人士和团队帮助一下会比较靠谱一些。希望对你有帮助~
“毕业论文”的英文:Graduation Dissertation
Dissertation 读法 英 [,dɪsə'teɪʃ(ə)n] 美 ['dɪsɚ'teʃən]
n. 论文,专题;学术演讲
短语:
1、academic dissertation 学位论文 ; 学术论文
2、Graduation Dissertation 毕业论文
3、Doctorate dissertation 博士论文
4、Dissertation Committee 论文委员会
5、dissertation topics 毕业论文题目
词义辨析:
article, paper,dissertation, essay, prose, thesis这组词都有“文章”的意思,其区别是:
1、article 多指在报刊、杂志上发表的非文艺性的文章,包括新闻报导、学术论文等。
2、paper 正式用词,多指在学术刊物上发表或在学术会议上宣读的专题论文,也指高等学校的学期论文,或学校里的作文练习。
3、dissertation 书面语用词,指独立研究后所写的较为详细的专题文章;也可指学位论文。
4、essay 指任何一种非小说性的,篇幅不长、结构简练的文章,如论说文、报道、评论、讽刺性杂文等。
5、prose 专指散文。
6、thesis 既可指毕业论文、学位论文,又可指一般的为阐述学术观点而写的论文。
例句:
1、Exploring "Trinity Working Mode" of Integrating Graduation Field Work, Graduation Dissertation and Employment on Graduation.
毕业实习、毕业论文与学生就业三位一体工作模式探索。
2、On Problems in Writing Graduation Dissertation
关于撰写毕业论文应该注意的问题。
毕业论文thesis[英][ˈθi:sɪs][美][ˈθisɪs]n.论文,毕业论文; 论点,论题; 命题; 复数:theses易混淆单词:THESIS例句: completed his doctorate in 1999 with his thesis on the technical subject of structural design. 1999年,朱竞翔获得博士学位,博士论文写的是结构设计的技术问题。 is a beguilingly simple thesis, one particularly attractive to the western business executives who have joinedthe china gold rush. 但这是一个具有欺性的简单论点,对参与中国淘金浪潮的西方企业高管尤其有吸引力。 have a grand new thesis of the emerging markets. 我们现在得出了一套全新的新兴市场理论。 question now is whether the overstretch thesis was wrong or simply premature. 目前问题是,过度扩张说是错误命题还是只是言之过早。 thesis is that women still do so badly at work mainly because we are not ambitious enough. 书的主题是:女性的工作表现仍如此糟糕,主要是因为我们不够有雄心。同义词:dissertation[英][ˌdɪsəˈteɪʃn][美][ˌdɪsərˈteɪʃn]n.专题论文,学位论文; 学术演讲; essay[英][ˈeseɪ][美][ˈɛsˌe, ɛˈse]n.散文; 随笔,杂记文; 尝试,企图; 试验; vt.尝试; 试验; 经常说的:English dissertation(英语论文)Graduation thesis(毕业论文)
你求翻译么是翻译哪种语言啊?这个没说清楚么怎么帮你翻译啊?一多汗的事情
论文(Paper)或:dissertation(论文)或:thesis(论文)经常说的:)~Englishdissertation(英语论文)Graduationthesis(毕业论文)
This paper is written from the job of Shenzhen Unicom WCDMA wireless network optimization. Do some theoretical analysis and practice verifications on the WCDMA network optimization .The paper consists of six parts. Part One gives a brief introduction to the WCDMA system and the significance of network optimization. Part Two gives introduction to Shenzhen Unicom's WCDMA network optimization project. Part Three introduces in detail on Shenzhen Unicom’s WCDMA network optimization process and methods. Introduced the principle and process of the single-point optimization and the cluster optimization. Part Four, Case introduced to Shenzhen Unicom’s WCDMA network optimization, single-station and cluster testing, analysis, improvement, optimize. The paper comes to the conclusion and prospects in the last part.不知道翻译的怎样,请高手赐教!
“毕业论文”用英文是dissertation dissertation[ˌdɪsəˈteɪʃn]n. 专题论文,学位论文;学术演讲 毕业论文; 博士论文; 论文; 学位论文 例句: was involved in writing his doctoral dissertation. 他在聚精会神地写他的博士论文.2. I have not yet footnoted my dissertation. 我还没有给我的论文加上脚注.3. I'm working my notes up into a dissertation. 我正在把我的笔记修改成论文.
“论文”一词的英文表达很多,通常因场合、用处不同而有不同的表达,下面罗列了几种,请楼主斟酌一下那一种是适合自己。*dissertation(博士学位)论文,(专题)论文,学术演讲:长而正式的论文,尤指大学里由博士学位攻读者所写的论文;学位论*disquisition专题论文;专题演讲,专题讨论:关于一个论题的正式讨论,常为书面形式*thesis命题论文:尤指出于获得学位的研究需要而改进原来观点以作为研究成果的论文*discourse(学术)讨论,研讨用的论文*paper作业形式的,为达到某一目的或效果(如学位)而写的
“毕业论文”用英文怎么说? Graduation thesis 毕业论文 用英语怎么说? Graduation thesis 期末论文用英语怎么说? 期末论文: Final paper毕业论文用英语怎么说 一般用thesis 博士论文dissertation "结业论文" 用英语怎么说? 直接翻译的话就是graduation p亥per,平时我们也常用academic research paper. 论文里面英文翻译的论怎么翻译,比如论什么什么?这里的论怎么翻译?? Discussion on....或者Study on... 如: 论当代中国农民的平等权利。 Study on equal rights of peasants in china today. 浅谈日本、韩国、中国大陆、台湾小学实施英语教育的现况 Discussion on current implementation of english education罚in japan, korea, china and *** . 发表论文用英语怎么说 推荐用一般过去式(时) I published the paper/article/essay(推荐前2者) entitled(提名为) *** in the journal/periodical(2选1) ***. 其中,两部分***都需斜体表示(张伶俐无法显示) 供参 我想问一下,毕业论文后面写的已发表论文,状态里面,英文怎么表达?比如Accepted 等等。 10分 submitted: 就是这篇文章已经提交给期刊,但还没有得到任何答复,还完全有被拒收的可能; under review: 就是文章进入评审阶段,一般提交给期刊的文章先要经过期刊助手对文章结构,字数等技术性检查,合格的话才送交主编,由主编邀请评审专家初审。under review 表明主编已经将论文送审了,结果仍未知; major revision: 文章需要大改,一般情况下如果(2-3位中)1位评审专家对文章提出一些尖锐、负面的意见,而另几位的意见比较正面,则主编往往会要求作者进行大改动;至此,文章还是有被接受的可能,但要看改动后的文章是否让评审专家或主编满意; minor revision: 小改动,至此文章被接受的可能已经达90%,只需要对文中小的差错进行修改即可接受; accepted:完全接受,但离出版印刷发行还有段时间; early online (or online ready):已经完全定型的文章还需要排队印刷发行,这个过程有的期刊会很长,1-2年,early online 或 online ready 就是先将文章在网上发布出来,供读者阅读。这时的文章 doi 号码已经有,也可以引用,但还没有正式的卷号,期号及页码; published: 最后印刷出版了 写论文 英语怎么说 write thesis 一般指毕业论文 论文比赛用英语怎么说 小型的论文比赛:Thesis Contest 贰术论坛:Academic Forum
怎么方面的?经济学吗?
Since the electronic type electric energy meter from last centuries90 time rise in domestic shouldUse, now has more than 10 years of development history, but as a result of the technology, application of pushWide aspects, in the current market share is not high. Intelligent electricTable is based on this, in recent years before the development of practical function more richElectric energy meter, it has a series of advantages and functions, is the traditional induction meter can not beCompared to meters in the structure, principle and characteristicsPrincipleElectronic type intelligent electric meter, the electronic meter based on, in recent years the development ofLaunch high-tech products, its composition, working principle and the traditional inductive energyTable has the very big difference. Induction type meter is mainly composed of aluminum plate, current and voltage lineRing, permanent magnet and other elements, its working principle is mainly through the current coil andDynamic disks in induction vortex interaction for measurement. Electronic type intelligent electricTable is mainly composed of electronic components, its working principle is based on customer firstElectric voltage and current sampling in real time, and then use special electric energy meter IC, onSampling the voltage and current signals are processed and converted into electrical energy, and directly proportional to the pulseImpulse output, finally through the single chip to carry on processing, control, display for electric pulseQuantity and output. We usually get smart metering of electricity when the A / D converter byThe number of pulses called pulse constant, for intelligent electric meter, which is one less than theThe more important constant, because the A / D converter in unit time by the number of pulsesA how many, will directly decide the meter measuring accuracy. The intelligent meterMostly uses a A / D converter design principles, but also some manufacturersProduction of the multi-user centralized intelligent electric meter with multiple families sharing one A / D conversionDevice, so that the electric energy measurement can only use time-sharing queuing to, will cause the meterQuantity accuracy declines, it should pay attention to in design and type to the adoption of electronic integrated circuit design, coupled with a remote communicationFunction, can connect with computer and the software control, and therefore, inductiveTable, smart meter no matter whether in performance or function have a greatAdvantage.(1) power: due to the adoption of smart meters electronic components design, therefore aAs each power is only 016w ~017W left and right sides, for multi-user centralizedIntelligent electric meter, the average household power is smaller. While each inductionMeter power consumption is about 117w.(2) accuracy: Table error range,210 electric energy meter in5% ~ 400% calibration current range measurement error of + 2%, and the current generalAll applications are accurate grade 110 level, the error is smaller. Induction ammeterError range from + 186% to -517%, but due to mechanical wear thisTo overcome the defects, leading to the induction watthour meter walked more and more slowly, the final error more and moreLarge. The State Grid has the induction meter to undertake selectiving examination, the results found that more than 50%Induction type meter in use5 years later, the error will exceed the permissible range.(3), the frequency range of overload overload multiples: smart meters up to 6To 8 times, with a wide range of. At present 8to 10ratio table is more and moreMulti user choice, and some can even reach20rate in wide range. Working frequencyRate of wide, in the 40HZ ~ 1000HZ range. While induction meter overload timesCount as only 4 times, and the working frequency range is only 45~ 55HZ.(4): smart meters due to the use of electronic technology, can be achieved by phaseThe communication protocol with the computer networking, through software programming the hardwareControl and management. Therefore the intelligent meter not only has the characteristics of small size, but also with theRemote control ( remote meter reading, remote cutting-supplying electricity ), multi-rate, identification of malignant load, electricity anti-stealing electricity, prepaid expenses and other functions, and can pass on the control software ofWith the parameter modification, to meet the different requirements of control functions, and these functions onIn the traditional induction meter it is difficult or meter function applicationAccording to the design of some engineering examples, the different characteristics, different engineeringElectrical properties, different use place, how to reasonably choose different functional characteristics of intelligentMeter, make some of shallow discuss.分享到
通信技术论文范文篇二 浅析量子通信技术 【摘要】量子通信作为既新鲜又古老的话题,它具有严格的信息传输特性,目前已经取得突破性进展,被通信领域和官方机构广泛关注。本文结合量子,对量子通信技术以及发展进行了简单的探讨。 【关键词】量子;通信;技术;发展 对量子信息进行研究是将量子力学作为研究基础,根据量子并行、纠缠以及不可克隆特性,探索量子编码、计算、传输的可能性,以新途径、思路、概念打破原有的芯片极限。从本质来说:量子信息是在量子物理观念上引发的效应。它的优势完全来源于量子并行,量子纠缠中的相干叠加为量子通讯提供了依据,量子密码更多的取决于波包塌缩。理论上,量子通信能够实现通信过程,最初是通过光纤实现的,由于光纤会受到自身与地理条件限制,不能实现远距离通信,所以不利于全球化。到1993年,隐形传输方式被提出,通过创建脱离实物的量子通信,用量子态进行信息传输,这就是原则上不能破译的技术。但是,我们应该看到,受环境噪声影响,量子纠缠会随着传输距离的拉长效果变差。 一、量子通信技术 (一)量子通信定义 到目前为止,量子通信依然没有准确的定义。从物力角度来看,它可以被理解为物力权限下,通过量子效应进行性能较高的通信;从信息学来看,量子通信是在量子力学原理以及量子隐形传输中的特有属性,或者利用量子测量完成信息传输的过程。 从量子基本理论来看,量子态是质子、中子、原子等粒子的具体状态,可以代表粒子旋转、能量、磁场和物理特性,它包含量子测不准原理和量子纠缠,同时也是现代物理学的重点。量子纠缠是来源一致的一对微观粒子在量子力学中的纠缠关系,同时这也是通过量子进行密码传递的基础。Heisenberg测不准原理作为力学基本原理,是同一时刻用相同精度对量子动量以及位置的测量,但是只能精确测定其中的一样结果。 (二)量子通信原理 量子通信素来具有速度快、容量大、保密性好等特征,它的过程就是量子力学原理的展现。从最典型的通信系统来说具体包含:量子态、量子测量容器与通道,拥有量子效应的有:原子、电子、光子等,它们都可以作为量子通信的信号。在这过程中,由于光信号拥有一定的传输性,所以常说的量子通信都是量子光通信。分发单光子作为实施量子通信空间的依据,利用空间技术能够实现空间量子的全球化通信,并且克服空间链路造成的距离局限。 利用纠缠量子中的隐形量子传输技术作为未来量子通信的核心,它的工作原理是:利用量子力学,由两个光子构成纠缠光子,不管它们在宇宙中距离多远,都不能分割状态。如果只是单独测量一个光子情况,可能会得到完全随机的测量结果;如果利用海森堡的测不准原理进行测量,只要测量一个光子状态,纵使它已经发生变化,另一个光子也会出现类似的变化,也就是塌缩。根据这一研究成果,Alice利用随机比特,随机转换已有的量子传输状态,在多次传输中,接受者利用量子信道接收;在对每个光子进行测量时,同时也随机改变了自己的基,一旦两人的基一样,一对互补随机数也就产生。如果此时窃听者窃听,就会破坏纠缠光子对,Alice与Bob也就发觉,所以运用这种方式进行通信是安全的。 (三)量子密码技术 从Heisenberg测不准原理我们可以知道,窃听不可能得到有效信息,与此同时,窃听量子信号也将会留下痕迹,让通信方察觉。密码技术通过这一原理判别是否存在有人窃取密码信息,保障密码安全。而密钥分配的基本原理则来源于偏振,在任意时刻,光子的偏振方向都拥有一定的随机性,所以需要在纠缠光子间分设偏振片。如果光子偏振片与偏振方向夹角较小时,通过滤光器偏振的几率很大,反之偏小。尤其是夹角为90度时,概率为0;夹角为45度时,概率是,夹角是0度时,概率就是1;然后利用公开渠道告诉对方旋转方式,将检测到的光子标记为1,没有检测到的填写0,而双方都能记录的二进制数列就是密码。对于半路监听的情况,在设置偏振片的同时,偏振方向的改变,这样就会让接受者与发送者数列出现差距。 (四)量子通信的安全性 从典型的数字通信来说:对信息逐比特,并且完全加密保护,这才是实质上的安全通信。但是它不能完全保障信息安全,在长度有限的密文理论中,经不住穷举法影响。同时,伪随机码的周期性,在重复使用密钥时,理论上能够被解码,只是周期越长,解码破译难度就会越大。如果将长度有限的随机码视为密钥,长期使用虽然也会具有周期特征,但是不能确保安全性。 从传统的通信保密系统来看,使用的是线路加密与终端加密整合的方式对其保护。电话保密网,是在话音终端上利用信息通信进行加密保护,而工作密钥则是伪随机码。 二、量子通信应用与发展 和传统通信相比,量子通信具有很多优势,它具有良好的抗干扰能力,并且不需要传统信道,量子密码安全性很高,一般不能被破译,线路时延接近0,所以具有很快的传输速度。目前,量子通信已经引起很多军方和国家政府的关注。因为它能建立起无法破译的系统,所以一直是日本、欧盟、美国科研机构发展与研究的内容。 在城域通信分发与生成系统中,通过互联量子路由器,不仅能为任意量子密码机构成量子密码,还能为成对通信保密机利用,它既能用于逐比特加密,也能非实时应用。在严格的专网安全通信中,通过以量子分发系统和密钥为支撑,在城域范畴,任何两个用户都能实现逐比特密钥量子加密通信,最后形成安全性有保障的通信系统。在广域高的通信网络中,受传输信道中的长度限制,它不可能直接创建出广域的通信网络。如果分段利用量子密钥进行实时加密,就能形成安全级别较高的广域通信。它的缺点是,不能全程端与端的加密,加密节点信息需要落地,所以存在安全隐患。目前,随着空间光信道量子通信的成熟,在天基平台建立好后,就能实施范围覆盖,从而拓展量子信道传输。在这过程中,一旦量子中继与存储取得突破,就能进一步拉长量子信道的输送距离,并且运用到更宽的领域。例如:在�潜安全系统中,深海潜艇与岸基指挥一直是公认的世界难题,只有运用甚长波进行系统通信,才能实现几百米水下通信,如果只是使用传统的加密方式,很难保障安全性,而利用量子隐形和存储将成为开辟潜通的新途径。 三、结束语 量子技术的应用与发展,作为现代科学与物理学的进步标志之一,它对人类发展以及科学建设都具有重要作用。因此,在实际工作中,必须充分利用通信技术,整合国内外发展经验,从各方面推进量子通信技术发展。 参考文献 [1]徐启建,金鑫,徐晓帆等.量子通信技术发展现状及应用前景分析[J].中国电子科学研究院学报,2009,4(5):491-497. [2]徐兵杰,刘文林,毛钧庆等.量子通信技术发展现状及面临的问题研究[J].通信技术,2014(5):463-468. [3]刘阳,缪蔚,殷浩等.通信保密技术的革命――量子保密通信技术综述[J].中国电子科学研究院学报,2012, 7(5):459-465. 看了“通信技术论文范文”的人还看: 1. 大学通信技术论文范文 2. 通信技术毕业论文范文 3. 通信技术论文范文 4. 关于通信工程论文范文 5. 大学通信技术论文范文(2)
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(二) 推荐方法 弦的特性在本节里,我们介绍圆心与其弦及弦上一点有关的特性。图1(a)显示一个圆圈与其弦AB。让P为圆圈内的一点,圆心为O,而AB是向θ方向经过P点的弦。以P 为中心的笛卡尔坐标系的四分之一圆周I 或II的端点定义为A,而B则定义为四分之一圆周III 或IV的端点。θ是由PX逆时针测量至AB的正角,θ ∈[0°, 180°]。同样地,φ是由PX逆时针测量至OP的正角。那么|AP|-|BP|=2|OP|cos(θ-φ). (1)下列的证明很直接。众所周知,任何圆周弦的垂直平分线都会经过圆心O(Rich, 1963)。以C作为AB的中心点,那么|AC|=|BC| and OC⊥AB.因此,|CP|=|OP|cos(θ-φ).|AP|-|BP|=(|AC|+|CP|)-(|BC|-|CP|)=2|CP|. 所以,|AP|-|BP|=2|OP|cos(θ-φ)图1(a)显示,O(xo,yo)与P(xp; yp)的坐标有下列的关系:xo=xp+acosφ,yo=yp-asinφ 而a=|OP|,yo方程里的减号反映在图像坐标系中,y值从上至下增加。如果我们有两条弦经过P点,可以从Eq. (1)直接得出两个方程,从中可解a 和 φ。 因此,可以从Eq. (2) 计算出(xo,yo)。具体细节在下一节展示。 圆心的计算考虑犹如图1(b)所示, A1B1 和A2B2两条弦是分别向θ1和θ2 方向 (θ1≠θ2)经过P (xp, yp)。以d1=|A1P|-|B1P| 及d2=|A2P|-|B2P|.那么从Eq.(1),d1=2acos(θ1-φ) 及d2=2acos(θ2-φ)将方程d1除以d2以及扩展余弦函数可解φ,我们得到...一堆公式(略)Eq. (4) 展示如何从两相交弦计算出圆心。具体地,如果圆周内有个P点被两条弦穿过,利用两弦所提供的d1, d2, θ1 及θ2,可以用Eq. (4) 计算出圆心位置。最简单的实例是θ1 = 0° 及θ2 = 90°。如果是那样,可以极易地显示θ1=0°横弦的中点是xo,θ2=90°竖弦的中点是yo。这个实例的计算精确,但由于只是使用竖横弦,这种计算方式可能不稳健。因此,本研究将使用随意产生方向的弦来配合Eq. (4)的计算。【英语牛人团】
“通信工程”译为Communication Engineering。
如要表达“我是通信工程专业的”之类的意思,可说:I major in Communication Engineering.
拓展资料:
通信工程,也称电信工程,是电子工程的一大重要分支,电子信息类子专业。
通信工程专业主要研究信号的产生、信息的传输、交换和处理,以及在计算机通信、数字通信、卫星通信、光纤通信、蜂窝通信、个人通信、平流层通信、多媒体技术、信息高速公路、数字程控交换等方面的理论和工程应用问题。
参考资料:百度百科-通信工程
基于WIN CE的ADSL线路参数研究ADSL line parameters research based on WIN CE CE (also known officially as Windows Embedded CE since version [2][3], and sometimes abbreviated WinCE) is a variation of Microsoft's Windows operating system for minimalistic computers and embedded systems. Windows CE is a distinctly different kernel, rather than a trimmed-down version of desktop Windows. It is not to be confused with Windows XP Embedded which is NT-based. It is supported on Intel x86 and compatibles, MIPS, ARM, and Hitachi SuperH CE is optimized for devices that have minimal storage—a Windows CE kernel may run in under a megabyte of memory. Devices are often configured without disk storage, and may be configured as a “closed” system that does not allow for end-user extension (for instance, it can be burned into ROM). Windows CE conforms to the definition of a real-time operating system, with a deterministic interrupt latency. It supports 256 priority levels and uses priority inheritance for dealing with priority inversion. The fundamental unit of execution is the thread. This helps to simplify the interface and improve execution has stated that the ‘CE’ is not an intentional initialism, but many people believe CE stands for ‘Consumer Electronics’ or ‘Compact Edition’; users often disparagingly called it “Wince”.[4] Microsoft says it implies a number of Windows CE design precepts, including “Compact, Connectable, Compatible, Companion, and Efficient.”[5] The first version, known during development under the codename “Pegasus”, featured a Windows-like GUI and a number of Microsoft's popular applications, all trimmed down for smaller storage, memory, and speed of the palmtops of the then, Windows CE has evolved into a component-based, embedded, real-time operating system. It is no longer targeted solely at hand-held computers. Many platforms have been based on the core Windows CE operating system, including Microsoft's AutoPC, Pocket PC 2000, Pocket PC 2002, Windows Mobile 2003, Windows Mobile 2003 SE, Windows Mobile , Windows Mobile 6, Smartphone 2002, Smartphone 2003 and many industrial devices and embedded systems. Windows CE even powered select games for the Sega Dreamcast, was the operating system of the controversial Gizmondo handheld, and can partially run on modified Microsoft Xbox game distinctive feature of Windows CE compared to other Microsoft operating systems is that large parts of it are offered in source code form. First, source code was offered to several vendors, so they could adjust it to their hardware. Then products like Platform Builder (an integrated environment for Windows CE OS image creation and integration, or customized operating system designs based on CE) offered several components in source code form to the general public. However, a number of core components that do not need adaptation to specific hardware environments (other than the CPU family) are still distributed in binary form toolsVisual StudioLate versions of Microsoft Visual Studio support projects for Windows CE / Windows Mobile, producing executable programs and platform images either as an emulator or attached by cable to an actual mobile device. A mobile device is not necessary to develop a CE program. The .NET Compact Framework supports a subset of the .NET Framework with projects in C# and , but not Managed C++.Platform BuilderThis programming tool is used for building the platform (BSP + Kernel), device drivers (shared source or custom made) and also the application. This is a one step environment to get the system up and running. One can also use Platform Builder to export an SDK (standard development kit) for the target microprocessor (SuperH, x86, MIPS, ARM etc.) to be used with another associated tool set named Visual C++ (eVC)The Embedded Visual C++ tool is for development of embedded application for Windows CE based devices. This tool can be used standalone using the SDK exported from Platform Builder or using the Platform Builder using the Platform Manager connectivity to Windows Mobile, Pocket PC, and SmartPhoneOften Windows CE, Windows Mobile, and Pocket PC are used interchangeably. This practice is not entirely accurate. Windows CE is a modular/componentized operating system that serves as the foundation of several classes of devices. Some of these modules provide subsets of other components' features (. varying levels of windowing support; DCOM vs COM), others which are mutually exclusive (Bitmap or TrueType font support), and others which add additional features to another component. One can buy a kit (the Platform Builder) which contains all these components and the tools with which to develop a custom platform. Applications such as Excel Mobile/Pocket Excel are not part of this kit. The older Handheld PC version of Pocket Word and several other older applications are included as samples, Mobile is best described as a subset of platforms based on a Windows CE underpinning. Currently, Pocket PC (now called Windows Mobile Classic), SmartPhone (Windows Mobile Standard), and PocketPC Phone Edition (Windows Mobile Professional) are the three main platforms under the Windows Mobile umbrella. Each platform utilizes different components of Windows CE, as well as supplemental features and applications suited for their respective PC and Windows Mobile is a Microsoft-defined custom platform for general PDA use, and consists of a Microsoft-defined set of minimum profiles (Professional Edition, Premium Edition) of software and hardware that is supported. The rules for manufacturing a Pocket PC device are stricter than those for producing a custom Windows CE-based platform. The defining characteristics of the Pocket PC are the digitizer as the primary Human Interface Device and its extremely portable SmartPhone platform is a feature rich OS and interface for cellular phone handsets. SmartPhone offers productivity features to business users, such as email, as well as multimedia capabilities for consumers. The SmartPhone interface relies heavily on joystick navigation and PhonePad input. Devices running SmartPhone do not include a touchscreen interface. SmartPhone devices generally resemble other cellular handset form factors, whereas most Phone Edition devices use a PDA form factor with a larger Mobile 5 supports USB and new devices running this OS will also conform to the USB Mass Storage Class, meaning the storage on PPC can be accessed from any USB-equipped PC, without requiring any extra software, except requiring a compliant host. In other words, you can use it as a flash productsCompetitors to consumer CE based PDA platforms like Pocket PC – the main application of Windows CE – are Java, Symbian OS, Palm OS, iPhone OS and Linux based packages like Qtopia Embedded Linux environment from Trolltech, Convergent Linux Platform from a La Mobile, and Access Linux Platform from Orange and secondary usage of CE is in devices in need of graphical user interfaces, (point of sale terminals, media centers, web tablets, thin clients) as the main selling point CE is the look and feel being similar to desktop Windows. The competition is Windows XP, Linux and graphical packages for simpler embedded operating an RTOS, Windows CE is also theoretically a competitor to any realtime operating system in the embedded space, like VxWorks, ITRON or eCos. The dominating method, however, of mixing Windows look and feel with realtime on the same hardware, is to run double operating systems using some virtualization technology, like TRANGO Hypervisor from TRANGO Virtual Processors or Intime from TenAsys in the case of Windows, and OS Ware from VirtualLogix, Padded Cell from Green Hills Software, OKL4 from Open Kernel Labs, TRANGO Hypervisor from TRANGO Virtual Processors, RTS Hypervisor from Real-Time Systems or PikeOS from Sysgo, in case of the Digital Subscriber Line (ADSL) is a form of DSL, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide. It does this by utilizing frequencies that are not used by a voice telephone call. A splitter - or microfilter - allows a single telephone connection to be used for both ADSL service and voice calls at the same time. Because phone lines vary in quality and were not originally engineered with DSL in mind, it can generally only be used over short distances, typically less than 3mi ( km) [William Stallings' book].At the telephone exchange the line generally terminates at a DSLAM where another frequency splitter separates the voice band signal for the conventional phone network. Data carried by the ADSL is typically routed over the telephone company's data network and eventually reaches a conventional internet network. In the UK under British Telecom the data network in question is its ATM network which in turn sends it to its IP network IP distinguishing characteristic of ADSL over other forms of DSL is that the volume of data flow is greater in one direction than the other, . it is asymmetric. Providers usually market ADSL as a service for consumers to connect to the Internet in a relatively passive mode: able to use the higher speed direction for the "download" from the Internet but not needing to run servers that would require high speed in the other are both technical and marketing reasons why ADSL is in many places the most common type offered to home users. On the technical side, there is likely to be more crosstalk from other circuits at the DSLAM end (where the wires from many local loops are close to each other) than at the customer premises. Thus the upload signal is weakest at the noisiest part of the local loop, while the download signal is strongest at the noisiest part of the local loop. It therefore makes technical sense to have the DSLAM transmit at a higher bit rate than does the modem on the customer end. Since the typical home user in fact does prefer a higher download speed, the telephone companies chose to make a virtue out of necessity, hence ADSL. On the marketing side, limiting upload speeds limits the attractiveness of this service to business customers, often causing them to purchase higher cost Digital Signal 1 services instead. In this fashion, it segments the digital communications market between business and home usersHow ADSL worksOn the wireCurrently, most ADSL communication is full duplex. Full duplex ADSL communication is usually achieved on a wire pair by either frequency division duplex (FDD), echo canceling duplex (ECD), or time division duplexing (TDD). FDM uses two separate frequency bands, referred to as the upstream and downstream bands. The upstream band is used for communication from the end user to the telephone central office. The downstream band is used for communicating from the central office to the end user. With standard ADSL (annex A), the band from kHz to 138 kHz is used for upstream communication, while 138 kHz – 1104 kHz is used for downstream communication. Each of these is further divided into smaller frequency channels of kHz. During initial training, the ADSL modem tests which of the available channels have an acceptable signal-to-noise ratio. The distance from the telephone exchange, noise on the copper wire, or interference from AM radio stations may introduce errors on some frequencies. By keeping the channels small, a high error rate on one frequency thus need not render the line unusable: the channel will not be used, merely resulting in reduced throughput on an otherwise functional ADSL may support usage of higher frequencies as a proprietary extension to the standard. However, this requires matching vendor-supplied equipment on both ends of the line, and will likely result in crosstalk issues that affect other lines in the same is a direct relationship between the number of channels available and the throughput capacity of the ADSL connection. The exact data capacity per channel depends on the modulation method used.[edit] ModulationADSL initially existed in two flavours (similar to VDSL), namely CAP and DMT. CAP was the de facto standard for ADSL deployments up until 1996, deployed in 90 percent of ADSL installs at the time. However, DMT was chosen for the first ITU-T ADSL standards, and (also called and respectively). Therefore all modern installations of ADSL are based on the DMT modulation J and M shift the upstream/downstream frequency split up to 276 kHz (from 138 kHz used in the commonly deployed annex A) in order to boost upstream rates. Additionally, the "all-digital-loop" variants of ADSL2 and ADSL2+ (annexes I and J) support an extra 256 kbit/s of upstream if the bandwidth normally used for POTS voice calls is allocated for ADSL the ADSL access utilizes the MHz band, ADSL2+ utilizes the MHz downstream and upstream rates displayed are theoretical maxima. Note also that because Digital subscriber line access multiplexers and ADSL modems may have been implemented based on differing or incomplete standards some manufacturers may advertise different speeds. For example, Ericsson has several devices that support non-standard upstream speeds of up to 2 Mbit/s in ADSL2 and ADSL2+.[edit] Installation issuesDue to the way it uses the frequency spectrum, ADSL deployment presents some issues. It is necessary to install appropriate frequency filters at the customer's premises, to avoid interferences with the voice service, while at the same time taking care to keep a clean signal level for the ADSL the early days of DSL, installation required a technician to visit the premises. A splitter was installed near the demarcation point, from which a dedicated data line was installed. This way, the DSL signal is separated earlier and is not attenuated inside the customer premises. However, this procedure is costly, and also caused problems with customers complaining about having to wait for the technician to perform the installation. As a result, many DSL vendors started offering a self-install option, in which they ship equipment and instructions to the customer. Instead of separating the DSL signal at the demarcation point, the opposite is done: the DSL signal is "filtered off" at each phone outlet by use of a low pass filter, also known as microfilter. This method does not require any rewiring inside the customer side effect of the move to the self-install model is that the DSL signal can be degraded, especially if more than 5 voiceband devices are connected to the line. The DSL signal is now present on all telephone wiring in the building, causing attenuation and echo. A way to circumvent this is to go back to the original model, and install one filter upstream from all telephone jacks in the building, except for the jack to which the DSL modem will be connected. Since this requires wiring changes by the customer and may not work on some household telephone wiring, it is rarely done. It is usually much easier to install filters at each telephone jack that is in use.
英文应该是Communication engineering。
通信工程专业主要做:研究信号的产生、信息的传输、交换和处理,以及在计算机通信、光纤通信、无线通信、交换与通信网等方面的理论和工程应用问题。就业方向有通信技术研发人员,通信产品销售人员,电信运营商工作人员等。
扩展资料
通信工程(也作电信工程,旧称远距离通信工程、弱电工程)是电子工程的一个重要分支,电子信息类子专业,同时也是其中一个基础学科。该学科关注的是通信过程中的信息传输和信号处理的原理和应用。本专业学习通信技术、通信系统和通信网等方面的知识,能在通信领域中从事研究、设计、制造、运营及在国民经济各部门和国防工业中从事开发、应用通信技术与设备。
参考资料通信工程_百度百科