【正文】 noisy environments by choosing digita1 transmission.要是我們考慮二進(jìn)制傳輸，完整的信息總會通過簡單地檢測脈沖的有無獲得。但事實并不總是這樣。噪聲會以多種不同方式引入傳輸路徑。采樣。近年來，人們對這三個環(huán)節(jié)的實現(xiàn)提出了許多不同的方案，我們將對其中一些主要的方案進(jìn)行討論。只能刻錄一次的光盤設(shè)備叫WORM設(shè)備，是write once, read many的縮寫。數(shù)據(jù)通過指示存儲著數(shù)據(jù)的盤片表面，軌道和扇區(qū)來引用。這種情況叫做磁頭碰撞。當(dāng)盤片以通常為3600轉(zhuǎn)每分的速度高速旋轉(zhuǎn)時，讀寫頭移過盤片表面。在過去，標(biāo)準(zhǔn)存取時間為65毫秒，而現(xiàn)在的標(biāo)準(zhǔn)為低于7毫秒。Unit5 502At first, these disk drives used 14 inch disks, but now they use 5 1/4 inch, 3 1/2 inch,2 1/2 inch, and 1 4/5 inch contrast to the floppy disk drive, hard disk drives hold from 80 megabytes to gigabytes and terabytes of purchasing a hard disk, consider storage capacity and seek time, a measure of a hard disk’s access smaller the numbers, the faster the the past, 65 milliseconds was the standard access time, but today the standard is less than 7 ，這些磁盤驅(qū)動采用14英寸磁盤，但現(xiàn)在采用的是5 1/4英寸，2 1/2英寸和1 4/5直徑的磁盤。有過剩電子時材料被稱為n型；缺失軌道電子時材料被稱為p型。鑒于異性相吸，原子核和圍繞其旋轉(zhuǎn)的電子間的力阻止了電子飛離到空間中。一種元素的原子和另一種元素的原子的差別在于其原子核中的質(zhì)子數(shù)和中子數(shù)。其中92種元素是天然形成的，其他的則是人造的。由于這些原因，數(shù)字電平?jīng)]有明確的規(guī)定，將每個狀態(tài)定義為指定電平的電壓范圍，例如4177。1 V and 177。一組具有相同意義的比特叫做字節(jié)，詞，或代碼。重復(fù)這個步驟（下一列為9247。二進(jìn)制系統(tǒng)中每個數(shù)字表示二的冪系數(shù)，而十進(jìn)制中表示十的冪系數(shù)。第一篇：電子信息英語專業(yè)英語詞組專業(yè)英語b篇翻譯Translated by何瑩婷，版權(quán)沒有，翻印不究。例如，十進(jìn)制數(shù)19在二進(jìn)制中表示為10011因為 10011=124+023+022+121+120=16+0+0+2+1=19 general method for converting from a decimal to a binary number is indicated in Table procedure is the the decimal number(in this illustration, 19)on the extreme divide by 2 and place the quotient(9)to the left and indicate the remainder(1)directly below this process(for the next column 9247。2=4余1），直到商為0截止。例如，表示10個數(shù)字（0,1,2，...9）和26個英文字母要用到36種不同的1和0的組合。 V.每個實體器件樣本的參數(shù)(如晶體管的VCE1 V 和 177。每種元素都各有其自己的標(biāo)識，也就是說，元素的物理和化學(xué)特性是獨一無二的，一種元素也不可以用物理和化學(xué)手段再分成簡單的元素。宇宙中的所有元素，也就是說所有的物質(zhì)，都是由質(zhì)子，中子和電子組成的。38last para Impurities may be added to pure results in semiconductor materials, which may either have an excess of free electrons or a deficiency of orbital an excess of electrons is present we call the material Ntype。N型和P型半導(dǎo)體都由加工材料制成。與軟盤驅(qū)動截然不同的是，硬盤驅(qū)動保存著兆字節(jié)到千兆字節(jié)、萬兆字節(jié)的信息。503Storing data on hard disks is similar to storing data on order to read or write data on the surface of the spinning disk platter, the disk drives are designed with access arms, or actuators.[1] The access arms, or actuators, contain one or more read/write heads per disk the disk rotates at a high rate of speed, usually 3,600 revolution per minute, the read/write heads move across its read/write heads float on a cushion of air and do not actually touch the surface of the disk.[2] The distance between the head and the surface varies from approximately ten to twenty millionths of an some form of contamination is introduced or if the alignment of the read/write heads is altered by something accidentally jarring the puter, the disk head can collide and damage the disk surface, causing a loss of event is known as a head of the time needed to repair the disk and to reconstruct the data that was lost, head crashes can be extremely costly to users in terms of both time and 。這些讀寫頭在高壓氣流上漂浮，移動時并不與盤片表面真正接觸。由于修復(fù)磁盤并重建數(shù)據(jù)需要一定的時間，磁頭碰撞會花費用戶相當(dāng)多的金錢和時間。516Most optical disks are prerecorded and cannot be modified by the disks are used for applications such as an auto parts catalog where the information is changed only occasionally, such as once a year, and a new updated optical disk is created.[3] Optical disk devices that provide for onetime recording are called WORM devices, an acronym for write once, read optical disk drives are just starting to be most mon erasable optical drives use magnetooptical technology, in which a magnetic field changes the polarity of a spot on the disk that has been heated by a laser.[4] 大多數(shù)光盤是事先錄好的，且不能被用戶修改?？刹翆懝獗P設(shè)備剛開始被使用。在這些討論中，我們會看到話路中的語音信號是如何轉(zhuǎn)換成一個幅值序列的，而每個幅值又被編碼，即以8位二進(jìn)制數(shù)的序列表示。672Digital transmission provides a powerful method for overing noisy can be introduced into transmission path in many different ways。也許是附近的閃電，汽車點火裝置的火花，或者是通信設(shè)備中熱的低電平噪聲。比如，從位于遙遠(yuǎn)太空中的衛(wèi)星接收到的信號極其微弱，其電平僅比噪聲稍高一點。相比之下，許多其他形式的傳輸系統(tǒng)利用被傳信號的波形或電平高低來傳送信息，而這些參數(shù)又極易受到傳輸路徑中噪聲和衰耗的影響。其實并不需要這樣，系統(tǒng)靠單一的編譯碼器（編碼器和其關(guān)聯(lián)的解碼器）運行，它有24，30,甚至120個單獨的信道。這個單元叫做時分多路器。 is the activity that makes the living environment more suitable for people,it is also the tool by which the technologies, manufacture ability, market needs and resources can be transferred into the useful results and ，也是一種可以將科學(xué)技術(shù)、制造能力、市場需求和資源轉(zhuǎn)換為有用的結(jié)果和產(chǎn)品的工具。設(shè)計是一種活動，它廣泛運用經(jīng)驗，知識，和技能，在一定的約束下，去尋找解決問題的最佳方法。8．Design is concerned with the whole process from identifying a problem, through to creating a solution and then testing ，解決方案以及對其試驗的整個過程密切相關(guān)。雖然紅色并非總是最惹人喜愛的顏色，但憑借紅色仍可喚起充滿激情的回應(yīng)。如果你在從事全球性的貿(mào)易，一定要充分調(diào)研自家品牌的色彩選擇，確保選用的顏色在國際市場上能夠準(zhǔn)確傳達(dá)品牌形象。特別是它的建筑藝術(shù)深深影響了西方建筑2000多年。三．，F(xiàn)PGA廣泛用于ASIC仿真、互聯(lián)邏輯集成，或者用作那些功能繁多、標(biāo)準(zhǔn)不斷變化的應(yīng)用的解決方案。SOC(System on Chip)is the product of digital application and the rapid development of microelectronics technology, and it is one of the main development directions of nextgeneration DSPbased integrates an application system on a single general, in order to meet the system performance requirements and improve power efficiency, DSP and MCU will be integrated to multiprocessor .“專用集成電路”不是微處理器這樣的通用芯片，而是一種為特殊用途設(shè)計的定制芯片。The generic term channel is normally used to denote a frequency in FDMA system,a time