Lesson 1 Analog and Digital Signal

1、專業(yè)英語通信類通信類為什么要學(xué)習(xí)這門課程？為什么要學(xué)習(xí)這門課程？ 與考研英語特點(diǎn)相似，復(fù)試 對(duì)讀研做科研有幫助，特別是圖像處理傳輸、光通信網(wǎng)絡(luò)方向等； 對(duì)工作有幫助 面臨畢業(yè)，你的選擇面臨畢業(yè)，你的選擇 考研，工作，出國？考研，工作，出國？課程關(guān)鍵詞課程關(guān)鍵詞 專業(yè)基礎(chǔ)專業(yè)基礎(chǔ)&英語基礎(chǔ)；英語基礎(chǔ)； 專業(yè)術(shù)語；專業(yè)術(shù)語； 長(zhǎng)難句長(zhǎng)難句 翻譯翻譯circuit周圍，巡回，繞行周圍，巡回，繞行電路電路bus公共汽車公共汽車總線，母線總線，母線short短的短的短路短路1.1.專業(yè)英語的特點(diǎn)專業(yè)英語的特點(diǎn)circuit周圍，巡回，繞行周圍，巡回，繞行電路電路bus公共汽車公共汽車總線，母線總

2、線，母線專業(yè)性：體現(xiàn)在它的特殊專業(yè)內(nèi)容和特殊專業(yè)專業(yè)性：體現(xiàn)在它的特殊專業(yè)內(nèi)容和特殊專業(yè)詞匯上詞匯上靈活性：體現(xiàn)在句子結(jié)構(gòu)和詞性的使用上。靈活性：體現(xiàn)在句子結(jié)構(gòu)和詞性的使用上。 如英語中的動(dòng)詞有的表示動(dòng)作，有的表示相對(duì)靜如英語中的動(dòng)詞有的表示動(dòng)作，有的表示相對(duì)靜止的狀態(tài)。止的狀態(tài)。short短的短的短路短路（1）TV differs from radio in that it sends and receives pictures.電視與無線電的區(qū)別在于電視能夠發(fā)送和接收?qǐng)D像。電視與無線電的區(qū)別在于電視能夠發(fā)送和接收?qǐng)D像。(表示狀態(tài)表示狀態(tài))（2）These two RF signals ar

3、e arranged to differ by a constant frequency.這兩個(gè)射頻信號(hào)用于找出一個(gè)固定頻率。這兩個(gè)射頻信號(hào)用于找出一個(gè)固定頻率。（表示動(dòng)作）（表示動(dòng)作）簡(jiǎn)明性：用盡可能少的單詞來清晰地表達(dá)原意簡(jiǎn)明性：用盡可能少的單詞來清晰地表達(dá)原意過去分詞短語可以取代被動(dòng)語態(tài)關(guān)系從句，現(xiàn)在分詞可以取過去分詞短語可以取代被動(dòng)語態(tài)關(guān)系從句，現(xiàn)在分詞可以取代主動(dòng)語態(tài)關(guān)系從句，如代主動(dòng)語態(tài)關(guān)系從句，如 In Britain electricity energy generated in power station is fed to the national Grid.不定式短語用以

4、替換表示目的、功能的從句，如不定式短語用以替換表示目的、功能的從句，如 The function of a fuse is to protect a circuit.常使用動(dòng)詞或名詞演化成的形容詞常使用動(dòng)詞或名詞演化成的形容詞(state-of-the-art最先進(jìn)的最先進(jìn)的)合成新詞多合成新詞多名詞性詞組多名詞性詞組多縮寫使用頻繁縮寫使用頻繁長(zhǎng)句多長(zhǎng)句多在說明書、手冊(cè)中廣泛使用祈使語句在說明書、手冊(cè)中廣泛使用祈使語句用虛擬語氣表達(dá)假設(shè)或建議用虛擬語氣表達(dá)假設(shè)或建議 (if.,或或surpose.)常用常用It句型結(jié)構(gòu)句型結(jié)構(gòu)被動(dòng)語態(tài)使用頻繁被動(dòng)語態(tài)使用頻繁 合成新詞Signal and Sy

5、stem 信號(hào)與系統(tǒng) Digital Signal Processing 數(shù)字信號(hào)處理 Electronic Design Automation 電子設(shè)計(jì)自動(dòng)化 縮寫 LED（Light Emitting Diode 發(fā)光二極管） LCD（Liquid Crystal Display 液晶顯示器） ATM（Asynchronous Transfer Mode 異步傳輸模式） WLAN（Wireless Local Area Network無線局域網(wǎng)） PTN (Packet Transport Network 分組傳送網(wǎng)） 祈使句 Turn on your computer and monit

6、or. Do not store CF cards in hot ,dusty or humid places.考核方式考核方式 上課內(nèi)容：上課內(nèi)容：1、3、4、5單元單元 閉卷：閉卷：100分分 題型：專業(yè)詞匯題型：專業(yè)詞匯翻譯翻譯（英譯漢、漢譯（英譯漢、漢譯英）；長(zhǎng)難句英）；長(zhǎng)難句翻譯翻譯（英譯漢）（英譯漢） 成績(jī)構(gòu)成：平時(shí)成績(jī)構(gòu)成：平時(shí)*30%+考試考試*70% 平時(shí)成績(jī)由作業(yè)、出勤、課堂提問等環(huán)平時(shí)成績(jī)由作業(yè)、出勤、課堂提問等環(huán)節(jié)給出節(jié)給出 考試前不劃重點(diǎn)、考點(diǎn)范圍，只回答同考試前不劃重點(diǎn)、考點(diǎn)范圍，只回答同學(xué)具體提出的問題學(xué)具體提出的問題Lesson 1 Analog and Dig

7、ital Signal專業(yè)知識(shí)回顧 模擬信號(hào)、離散信號(hào)、數(shù)字信號(hào)模擬信號(hào)、離散信號(hào)、數(shù)字信號(hào) 數(shù)字信號(hào)數(shù)字信號(hào)VSVS模擬信號(hào)模擬信號(hào) 模數(shù)轉(zhuǎn)換模數(shù)轉(zhuǎn)換Lesson 1 Analog and Digital Signal How is the sound recorded in the computer? And how is the sound in the computer broadcasted? As everyone knows, vibrating of the substance causes the sound. We often record the sound by com

8、puters, and hear the amplified sound from the radios, computers and other electric devices. Then, how does the sound go into the electric system? And how can the sound in the electric systems be broadcast 播送，廣播 vibrating of the substance 物體的震動(dòng) amplified 放大的 transformed 傳輸 analog quantity 模擬量 digital

9、 quantity 數(shù)字量 a discrete set of 一組離散的 quantitatively 定量地 occur in nature 在自然界存在Lesson 1 Analog and Digital SignalLesson 1 Analog and Digital Signaltransformed and be heard again? 1. What is an analog quantity-a temperature line An analog quantity is one having continuous values. A digital quantity i

10、s one having a discrete set of values. Most things that can be measured quantitatively occur in nature in analog form. For example, the air temperature changes over a continuous range of values. During a given day,the temperature does not go from, say, 70。to 71。Lesson 1 Analog and Digital Signalinst

11、antaneously; it takes on all the infinite valuesin between. If you graphed the temperature on a typical summer day, you would have a smooth, continuous curve in Fig.1-2. Other examples of analog quantities are time,pressure, distance, and sound, as shown in Fig.1-3. Several kinds of analog signals,

12、as shown in Fig.1-4. Lesson 1 Analog and Digital Signal instantaneously 瞬間 takes on 原意為“占據(jù)” it takes on all the infinite values in between. 在這個(gè)范圍內(nèi)連續(xù)變化。 graphed 繪制圖形 curve 曲線Lesson 1 Analog and Digital Signal 2. What is a digital quantity-still a temperatureline Rather than graphing the temperature o

13、n a continuous basis, suppose you just take a temperature reading every hour. Now you havesampled values representing the temperature at discrete points in time (every hour) over a 24-hour period, as indicated in Fig.1-5. You haveeffectively converted an analog quantity to a formthat can now be digi

14、tized by representing each sampled value by a digital code. It is important on a continuous basis 在連續(xù)的基礎(chǔ)上 sampled values 采樣值 in time 及時(shí)，準(zhǔn)時(shí)，這里翻譯成定時(shí)也可以 indicated 表示 digitized 數(shù)字化Lesson 1 Analog and Digital SignalLesson 1 Analog and Digital Signalto realize that Fig.1-5 itself is not the digital repres

15、entation of the analog quantity. Each value represented by a dot can be digitized by representing it as a digital code thatconsists of a series of 1s an 0s. Digital representation has certain advantagesover analog representation in electronics applications. For one thing, digital data can be process

16、ed and transmitted more efficiently and reliably than analog data. Also, digital data has a great advantage when storage is necessary. consists of 由組成 has certain advantages over 有一定的優(yōu)勢(shì) applications 應(yīng)用 processed 處理 transmitted 傳輸 efficiently 有效地 efficiency 有效性 reliably 可靠地 reliability 可靠性Lesson 1 An

17、alog and Digital SignalLesson 1 Analog and Digital SignalFor example, music when converted to digital form can be stored more compactly and reproduced with greater accuracy and clarity than is possible when it is in analog form. Noise(unwanted voltage fluctuations) does not affectdigital data nearly

18、 as much as it does analog signals. Several kinds of digital signals, as shown in Fig.1-6. music when converted to digital form can be stored more compactly and reproduced with greater accuracy and clarity than is possible when it is in analog form.Lesson 1 Analog and Digital Signal 相對(duì)于模擬形式，如果我們把音樂轉(zhuǎn)

19、換成數(shù)字形式，存儲(chǔ)的時(shí)候可以更好地壓縮，而且重現(xiàn)聲音時(shí)，也更加精確和清晰。back fluctuations 波動(dòng)Noise (unwanted voltage fluctuations) does not affect digital data nearly as much as it does analog signals.notnearly as much as 遠(yuǎn)遠(yuǎn)不如數(shù)字信號(hào)受到的噪聲影響遠(yuǎn)遠(yuǎn)不如模擬信號(hào)大。backLesson 1 Analog and Digital SignalLesson 1 Analog and Digital Signal3. An example of

20、analog system-a speaker A public address system, used to amplify sound so that it can be heard by a large audience, is one simple example of an application of analog electronics. The basic diagram in Fig.1-8 illustrates that sound waves,which are analog in nature, are picked up by amicrophone and co

21、nverted to a small analog voltage called the audio signal. This voltage varies continuously as the volume and frequency of the sound changes and is applied address 講話，這里翻譯為廣播 A public address system 公共廣播系統(tǒng) audience 聽眾 illustrates 說明 picked up 采集 voltage 電壓 audio signal 音頻信號(hào) volume 音量 frequency 頻率Les

22、son 1 Analog and Digital SignalLesson 1 Analog and Digital Signalto the input of a linear amplifier. The output of the amplifier, which is an increased reproductionof input voltage, goes to the speaker (s). The speaker changes the amplified audio signal back to sound waves that have a much greater v

23、olumethan the original sound waves picked up by the microphone. 4. An example of analog and digital system-also a speaker The basic block diagram in Fig.1-9 illustratesa system using digital and analog methods. next a linear amplifier 線性放大器 an increased reproduction of input voltage 輸入電壓的放大量 origina

24、l 原始的，最初的 block diagram 框圖Lesson 1 Analog and Digital SignalLesson 1 Analog and Digital Signal The compact disk (CD) player is an example of a system in which both digital and analog circuits are used. The simplified block diagram inFig.1-9 illustrates the basic principle. Music in digital form is stored on the compact disk. A la