Điện tử - Viễn thông chuyên ngành Tiếng Anh: Phần 2

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Phần 2 của Tài liệu Tiếng Anh chuyên ngành Điện tử - Viễn thông gồm các nội dung từ unit 14 đến unit 20. Ngoài ra trong phần này còn cung cấp các bài kiểm tra giữa và cuối khoá học, các bài dịch mẫu cũng như phần giải đáp các bài tập của từng bài trong phần phụ lục giúp cho sinh viên tự đánh giá kết quả học tập của mình và tra cứu những đoạn dịch mẫu khi cần. Mời các bạn cùng tham khảo.

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Nội dung Text: Điện tử - Viễn thông chuyên ngành Tiếng Anh: Phần 2

Unit 14 COMPACT DISC A digital recording system, kn ow n as a co mpact disc (CD) system, was introduced in 1982. This uses a laser optical m e c h a n is m in w h ich a laser beam reads marks on the surface o f a specially prepared perspex disk. It gives near-perfect reproduction o f sound and the sound quality does not deteriorate with use. This breakthrough co mpletely replaced the grooved phono grap h record by the end o f the 20"' century. The C D differs from the standard phonograph record in two principal ways. The recorded signal on it is in PCM digital format and it is a grooveless, co ntactless system. Instead of a groove, a C D has a spiral track ma de o f a series o f "pits" o f different lengths. These pits represent the pulse code. The master disc for a C D is an optically flat glass disc co ated with a resist. The resist is a chemi cal that is impervious to an other chemical, called an etchant, which dissolves glass. The mast er is placed on a turntable. Abo ve it is a re co rdi ng head containing a laser. The digital signal to be recorded is fed to the laser, turning the laser on and off in respond to the binary on-o ff signal. W h e n the laser is on. it b u m s away a small am ount o f the resist on the disc. While the disc turns, the recording head moves across the disc, leaving a spiral track of elongated "burns" in the resist surface. After the recording is complete, the glass m a st er is placed in the c h e m i c a l etchant bath. This "developing" re moves glass only where the resist is burned away. The spiral track now contains a series o f small pits o f varying length and con stan t depth. The c om m e rc ia l C D ma ss produced from the m a st er is m a de from a clear plastic. It is about 0.05 inch (1.3 millimeters) thick. The spiral track of pits is on its top surface. This surface has a coating of al u m in u m so that it reflects light. In playing a CD, an e xtr e m el y fine laser b e am is focused on the spiral track from beneath the disc. As the disc turns in the C D player, the laser beam is focused on the pits (seen from below the disc as bumps). At the same time, the be am m ov e s from the center of the disc outward, following the spiral. Since there is no m e ch a ni c al contact with the disc, a C D player must keep the be am focused and follow the spiral by "watching" how the light is reflected from the C D and correcting its position as needed.
Unit 14 99 The laser beam is reflected from the bumps onto a photo detector. The photo detector sends out a signal whenever light hits it and remains off when there is not enough light. These ons and offs produce a digital signal that is the same as the original digital signal recorded on the CD. This signal is then decoded by a D/A converter into the original analogue signal. The analogue signal is amplified and converted to sound by loudspeakers. (Text taken from The N e w book o f p o p u la r s cience by Grolier International. Inc.) Words and expressions coat (v) phu, trang (len) depth (n) do sau elongate (v) keo dai, lam dai etchant (n) chat khac 3n mon extremely (adv) ci/c ky, het sire focus (v) lam hoi tu, dieu tieu groove (n/v) ranh, xe ranh imperious (adj) khong tham (nirdc), khong lot (qua) introduce (v) gidi thieu, dua vao sir dung perspex (n) nhiia pech-pech pit (n) vet ro principal (adj) chinh, chu yeu spiral (adj) (thuoc, co hinh) tron oc turntable (n) ban quay, ban xoay 1. M ain idea W hich sta tem en t best expresses the m ain idea o f the text? 1. Compact disk is a plastic disc for the reproduction of recorded sound. 2. The C D represents a technological advancement over the groove-and-stvlus m e ch a nis m o f the phonograph in that nothing actually touches the surface of the disc. 3. The CD is a digital recording system w'here data writing and reading is done using a laser beam. 2. Q u estion s A n sw e r th e fo llo w in g questions. 1. What is the recording me ch a nis m o f the compact disk?
2_____________________________ Tieng A nh chuyen nganh Dien ttf - Vien thong 2. How does the C D represent the audio pattern? 3. What is special about the material with which the master disc is coated ? 4. A compact disk system called a contactless system. W h y ? 5. What is the function of the D/A converter? 3. U n d e r s t a n d i n g t h e pa s s a g e D ecide w hether the fo llo w in g statem ents are true or fa ls e (TIF) by referrin g to the in fo rm a tio n in the text. T h en m ake the necessary ch anges so th a t the fa lse statem ents becom e true. 1 The longer the C D is in use. the worse sound quality it produces. 2 The digital signal to be recorded determines the length o f the pits. 3 “ Developing” means burning away a small amount of the resist on the disc. 4 The C D player is to make sure the light beam falls on the right positions on the disk. 5 The photo detector sends out a signal whe nev er light hits a signal. 4. C o n t e x t u a l r e f e r e n c e W hat do the words in bold refer to? which (para 1) ....................................... It (para 1) ....................................... it (para 2) ....................................... it (para 5) ....................................... its (para 6) ....................................... 5. C o n t e n t re vie w F ill in the m issin g in fo rm a tio n in the fo llo w in g passage. While the phonogra ph record is an analogue recording system, the C D is i ( 1 ) ...........................one. The phonog ra ph disk uses the mechanical or analo gue meth transmitted to the C D by a (3) ........................... After cut by the laser, the d i A p
Unit 14 101 (4) in an etching chemical that eats away the areas (5) ........................... have been exposed to the laser beam and thus produces the ( 6 ) ........................... When the disc is inserted into a playback unit, a light beam from a low-intensity laser is alternately (7) ........................... by the pits and is "read" by an optical sensor. which ( 8 ) ........................... the varying intensities of light into digital signals. The digital signals are then converted into sound impulses. 6. English • V ietn am ese translation Translate th e fo llo w in g sentences into Vietnam ese, basing on the inform ation in the text. 1. The CD was a technological breakthrough in the latter half of the 20th century. Due to the use o f PCM and contactless principle, this kind of disk provided high durability and excellent sound quality, making it a perfect alternative for the groove record. 2. To play back the recording, the disk is made to revolve at a constant speed and a laser beam is directed at its surface. 7. V ietnam ese - E nglish translation Translate the fo llo w in g sentences into E nglish, basing on the info rm a tio n in the 1. O dia C D - R O M d un g mot ch um tia la-de cong suat thap de doc d u lieu da duoc ma hoa thanh so nhi phan. 2. Cac du- lieu nay trudc do da dupe ghi vao mot dia quang dudi dang cac vet rd li ti. 3. Cho tdi nay. dia CD da thay the hoan toan loai dia hat lam bang nhua vinyl thong thudng n h d chat lupng am thanh gan nhu hoan hao, do ben va do tin cay cao.
102 Tieng A n h chuyen nganh Dien tit - Vien thong 8. Bai djch th am khao OTa compact He thong ghi am so goi la he thong dia co mpact (CD) duoc dira vao sir dung tir nam 1982. He thong nay sir dung co cau quan g la-de trong do mot ch um tia la-de doc cac dau tren be mat cua mot loai dia lam bang chat deo pech-pech duoc xu ly mot cach dac biet. He thong tai tao am thanh gan nhu hoan hao, va chat luong am thanh khong hi suy giam trong qua trinh sir dung. C on g nghe co tfnh dot pha nay da thay the hoan loan c ho loai dia hat kieu xe ranh vao cuoi the ky XX. Dia C D khac vcri dia hat thong thudng d hai diem. Tin hieu du o c ghi tren dia la dang dieu che xung m a (PCM) va no la mot he thong kh ong xe ranh. kho ng tiep xuc. Thay the cho hinh thuc xe ranh, dia C D cd mot dudng tron oc tao bdi mot day cac vet rd cd do dai khac nhau. Cac vet rd dai dien cho xung ma. Dia chuan de san xuat dia C D la mot dia thuy tinh dat do phang q u a n g hoc. dupe phu mot ldp can quang. Chat can qu an g la mot loai hoa chat cd tinh chat tro doi vdi mot hoa chat khac, goi la chat khac an m o n cd kha nang hoa tan thuy tinh. Dia nay duoc dat tren mot ban quay. Phfa tren ban quay la mot dau ghi cd mot sung la-de. Tfn hieu so cdn ghi dupe cap tdi la-de, didu khien su dong m d cua la-de phu hop vdi cac trang thai d o n g / m o cua tfn hieu nhi phan. Khi c h u m la-de dong, no dot chay mot lupng nho chat can q ua ng tren dia. Khi dia quay, dau ghi di c hu ye n tren mat dia tao ra mot d u dn g hinh tron oc bao g om nhung vet c hay hinh thon dai tren b£ mat chat can quang. Sau khi hoan thanh viec ghi. ngudi ta dat phan thuy tinh cua dia vao be an mon hoa hoc. Chat boc taiy nay lam bong thuy tinh chi d nhung noi ldp can qua ng bi dot chay. Luc nay xuat hien du dng hinh tron oc gd m cac vet rd nhd cd do dai khac nhau nhung do sau nh u nhau. Dia C D thuong pham tao ra tu dia goc cd chat lieu lam bang chat d e o tr on g suot. Dia cd do day khoan g 0.05 inso (tuc khoang 1.3 mm). D u d n g hinh n o n oc ch ua cac Id nhd nam d mat tren cua dia. Be mat nay dupe phu bang nh om de phan xa anh sang. Khi doc dia CD. mot c h u m tia la-de cuc ma nh dupe hoi tu len du d n g hinh tron oc tir phfa dudi dia. Khi dia quay trong d CD. c h u m tia la-de hoi tu tren cac Id inhin tir dudi len giong nh u nhung cuc budu). Do ng thdi chu m tia di do ng tir tam dia ra ngoai theo d u dn g hinh tron oc. VI khong cd tiep xuc c o hoc vdi dia. 6 C D phai duy tri mi hoi tu churn tia va di theo d u d n g hinh tron oc bang cach “ theo d o i ” chiim tia du oc phan xa nhu the nao tir dia C D va dieu chinh vi tri ciia no khi can thiet.
Unit 14 103 C hu m la-de du gc phan xa tir cac bucru vao cac dau nhay quang. Dau nhay quang chuy en tin hieu ra ngoai bat cir luc nao anh sang tac dong vao no va bi ngat mach khi anh sang khong dii. Viec dong ngat nay ciia dau nhay quang se tao ra tin hieu so giong tfn hieu so ban dau da duoc ghi tren dia CD. Tiep theo. tfn hieu nay se duoc giai ma boi bo chuyen doi D/A thanh tfn hieu tuong tu ban dau. Tfn hieu tuong tu nay du oc khuech dai va duoc loa bien doi thanh am thanh.
Unit 15 HIGH-DEFINITION TELEVISION In the world, a race is on to produce a new generation o f television sets. In Europe, the term High-Definition Television ( H D T V ) is used. In the USA. such a television set is k n o w n as A dvanced Television (ATV). The Japanese, w ho were the first to start work on the new technology, in 1974, called their sy stem Hi-Vision. However, despite having different names, these new sets share certain features. High-definition television, HD TV , is a new format that promises to deliver a dramatically sharper picture than is offered by current television te chn ol ogy - free of static, the ghostlike double images, and the other forms o f interference that so frequently annoy today's television viewers. H D T V sets will also have the capacity to produce sound in digital stereo, with quality prevailing that o f today s most upscale compact-disc players. Despite the e norm ous promise o f this new format, H D T V still faces man\ difficulties before it replaces today's c o n ven tion a l T V sets. T he se difficulties include the technical challenges o f broadcasting an H D T V signal, the c o m p le x process of government regulation, and - not least by any m e a n s - acceptance o f the expensive new format by consumers. In a conventional television set. the picture consists of 625 lines, with a total of 12,000 dots. As a signal is broadcast to the set's receiver, the lines are scanned instantaneously and continually. In effect the television receives 30 pictures per second: the h u m a n eye interprets this stream as one continu ous image. In the cath ode- ray tube (CR T) inside a T V set, the signal reaches the picture tube in the form of an electron beam that is fired at a phos phor coating on the tube's surface. The screen then glows when struck by the electrons. Thus, the broadcast image is re-created with all its brightness and colour o f the original image. This 625-line signal is kn ow n as NTSC, after the National Television System Com mi tte e, which selected the formal as the U.S. standard in television's early stage o f de vel opm ent in the early 1950s. The prob lem w ith NTSC and other conventional formats is that the line structure re mains too evident on the television screen.
U nit 15 105 HD TV cam eras and receivers work by increasing the amount o f video information in the picture - supplying roughly five times as muc h information as NTSC. Instead ol the conventional 30 pictures per second of today's standard. H DTV operates at nearly 60 pictures - nearly one billion bits of information - per second. More information means a much sharper image. Instead of 625 lines, an HD picture consists of 1.250 lines and is co mpo sed o f four times as ma ny dots. With HDTV, the picture ma tches the clarity and resolution o f the 35-millimeter film images seen in movie theaters. H DTV de signers also intend to copy the screen d i m e n s i o n of a movie theater. Until the arrival of television, most Hollywood movies were made in a square format, with an aspect ratio o f 4 to 3. meaning four units of width to three of height. In the mid 1950s, when television threatened to keep moviegoers at home. Hollywood hit on a new attraction: the wide-screen format that more closely mimics a hum an s field of vision. HDTV developers are basing their hopes on this more visually pleasing format, which is closer to a movie screen's aspect ratio of 16 to 9. Experts point out that the HDTV picture can be m u c h bigger without becomi ng coarse, employing five times the information in the picture and five times the resolution, with the acc om pa nim e nt of digital sound. (Text taken from The N e w hook o f p o p u la r s cience by Grolier International. Inc.) Words and expressions acceptance (n) s i/tie p nhan, chap nhan accompaniment (n) s ird i kern, dong hanh brightness (n) do sang challenge (n) thach thuc clarity (n) s i/s a n g sua, ro rang coarse (adj) tho, tho rap conventional (adj) (thuoc) thong thudng, thong dung dimension (n) kfch thudc, chieu evident (adj) hien nhien, ro ret field of vision trudng nhin instantaneously (adv) (mot cach) tdc thdi prevail (v) thinh hanh, sanh ngang vai promise (v) hda, hda hen ratio (n) ti le resolution (n) do phan giai roughly (adv) xap xi, i/dc chimg sharp (adj) sac net, sac nhon
106 Tieng A nh chuyen nganh Dien tu - Vien thong 1. M a i n idea W hich sta tem en t best expresses the m ain idea o f the text? W hy did yo u elim inate the other choices? 1. HDTV will gradually replace conventional TV sets. 2. H DTV has several advantages over t o d a y ’s TV sets. 3. HDTV provides more realistic pictures than are offered by present televisions. 2. Q u e s t i o n s A n sw e r the fo llo w in g questions. 1.What in existing televisions does not please T V viewers? 2. What ma kes up a complete image as it is seen on TV screen by viewers? 3. What section of the picture tube is hit by the electron beam ? 4. How is the TV image made sharper? 5. What feature do the designers think might be the attraction of H D T V 1 3. U n d ersta n d in g the passage D ecide w h eth er the fo llo w in g statem ents are true or fa lse (TIF) by referring to the in fo rm a tio n in th e text. T hen m ake the necessary changes so that the false statem ents becom e true. 1 ..... H D T V will be equipped w ith more than one sound track. 2 ......H DTV makers feel sure that consumers will readily accept the new product. 3 ..... An H D T V picture is ma de up o f 46.00 0 dots. 4 ..... The H D T V s cr ee n 's aspect ratio is exactly 16: 9. 5 ..... The resolution of H D T V is higher than that of ordinary sets. 4. V ocabulary 1. As used in paragraph 2. prevailing can be best replaced b\ A. more valuable than
Unit 15 107 B. better than C. sharper than D. worse than 2. As used in paragraph 3, conventional can be best replaced by A. existing B. invented C. modern D. upgraded 3. As used in paragraph 4, the phrase is fir e d at can be best replaced by A. burns B. is heated C. is emitted D. hits 4. As used paragraph 5, roughly can be best replaced by A. generally B. exactly C. approximately D. basically 5. As used in paragraph 6. d im ension can be best replaced bv A. area B. line C. size D. d ia m e te r 5. C ontent review F ill in th e m issin g in fo rm a tio n in the fo llo w in g passage. HDTV, this term refers to any system yielding significantly greater picture resolution than ( 1 ) ..................... of the ordinary 625-line screen. Conventional television transmits signals in analog (2 ).....................—i.e.. as a series ol waves that can reproduce the original images and sounds captured by cameras and microphones: these waves are then (3 ) ..................... and amplified within the television set. Digital H D T V systems, by contrast, transmit pictures and ( 4 ).....................in the form of (5)....................... d a ta —i.e., in
108 Tieng A nh chuyen nganh Dien tit - Vien thong the 0's and l's of the binary co mputer code. Digital H DTV can provide wide-screen (6 )..................... which are sharper, clearer and sound with very little ( 7 ) ..................... or other imperfections. Perhaps more importantly, digital (8 ).....................would potentially be able to send, store, and manipulate images as well as receive them, thereby merging the functions of the television set with those of a small computer. 6. English - V ietnam ese translation Translate the fo llo w in g sentences into Vietnam ese, basing on the in fo rm a tio n in the text. 1. A television's audiovisual signal begins with the conversion of an image and accompan ying sound into an electronic code by a television camera. 2. The reason why a wider range of frequencies can be used to transmit each HDTV channel is that these frequencies are higher than those c o m m o n ly used at present. 7. V ietnam ese - E nglish translation Translate the follow ing sentences into English, basing on the inform ation in the text. 1. Hien nay trien vong phat trien HDTV da kha quan hon nhieu so voi vai nam trudc day. 2. Mac du co nhieu uu diem so voi truyen hinh thong thuong. qua trinh chuyen sang truyen hinh co do net cao con gap phai nhieu kho khan, m a truoc het la gia thanh con qua cao. S. Bai dich tham khao Truyen hinh do net cao Tren the gidi hien dang dien ra cuoc chay dua ve che tao mot the he m a \ thu hinh moi. Tai chau Au. ngudi ta dung thuat ngu High-Defimtion Television ( H D T \ - Truyen hinh do net cao). Tai My. loai may thu hinh nay duoc goi la Advanced Television
Unit 15 109 - Truydn hinh tien tie'n). Ngudi Nhat Ban, nhung ngudi dau tien nghien curu phat trien cong nghe mdi nay vao nam 1974, goi he thong cua minh la Hi-Vision. Tuy nhien. du cd nhung ten goi khac nhau cac may thu hinh loai nay deu mang nhung dac tinh giong nhau. Truyen hinh do net cao, HD TV, la mot phuong thuc truyen hinh mdi hua hen mang lai hinh anh cuc ky sSc net so vdi cong nghe truvdn hinh thong dun g hien nay. Cong nghe truyen hinh mdi me nay khac phuc duoc nhung hien tupng dien tinh. hinh hinh kep bong ma. cung nhu cac loai nhidu khac gay kho chiu cho ngudi xem. May thu hinh HDTV cung se cd kha nang tao ra am thanh stereo so, vdi chat lupng sanh ngang vdi cac dau dTa CD tot nhat hien nay. Mac du cd nhurng hura hen cua mot loai hinh truv^n hinh mdi. HDTV van ddi mat vdi nhieu kho khan trudc khi thay the cho cac may thu hinh thong thudng hien nay. Nhung kho khan nay bao gom nhung thach thurc \'6 mat ky thuat phat tin hieu HDTV, qua trinh dieu chinh chinh sach phuc tap cua cac chinh phu. va - mot phan khong kern phan quan trong - su chap nhan gia thanh cao doi vdi loai truyen hinh nay cua khach hang. Trong m a y thu hinh thong thudng, mdi khung hinh cd cau tao gd m 625 dong, vdi tdng so 12.000 diem. Khi tin hieu dupe truyen tdi ma y thu, cac dong dupe quet gan nhu tire thdi va lien tuc. M a y thu hinh nhan dupe 30 hinh anh/s. mat ngudi cam nhan dong hinh anh nay nhu la mot hinh anh lien tuc. Trong ong tia ca-tot (CRT) dat ben trong may thu hinh, tin hieu den den hinh dudi dang mot chum electron chieu len ldp phu phdt-pho tren mat trong cua den hinh. Man hinh sang len khi cac dien tu va vao. Do do. hinh anh truyen hinh dupe tai tao vdi do sang va mau sac giong nhu hinh anh ban dau. Tin hieu 625 do ng nay dupe goi la NTSC, ten vie't tat cua Uy ban He thong TruyC'n hinh Qudc gia. la c o q uan da chon loai hinh nay lam tieu chuan quoc gia cua My nga \ trong giai doan phat tri£n dau tien vao dau nhung nam 1950. Van de ton tai cua truyen hinh NTSC va cac loai hinh truyen hinh thong thudng khac la d cho cau true do ng van con hien qua rd tren m a n hinh. May q ua y ca -m e- ra va ma y thu hinh H DTV hoat dong bang cach tang lupng thong tin video tren hinh anh - cung cap mot lupng thong tin ldn gap 5 lan so vdi truven hinh NTSC. Th ay c ho toe do 30 hinh/s theo tieu chuain thong thudng hien nay. HDTV hoat dong d toe do gan 60 hinh/s. nghTa la gan mot tv bit thong tin/s. T h o n g tin nhiC; u hon dong nghia vdi hinh anh sac net hon. Thay cho khuon hinh 625 dong, khuon hinh HD cd cau tao g d m 1.250 dong va cd so diem nhieu gap bon lan. Vdi HD TV , khuon hinh nay dat du p e do rd va do phan giai cua hinh anh phim 35-m m chieu trong cac rap chieu bong. Cac nha thiet ke H D TV cung dang d u dinh sao chep kfch thudc man anh cua cac rap chieu bong. Tr ud c khi truyen hinh xuat hien. phan ldn cac bo phim lam tai Hd-li-iit
110 Tieng A nh chuyen nganh Dien tu - Vien thong deu dupe san xuat theo khuon hinh vuong. vcri ti le 4:3. nghTa la bon don vi chieu rong ung vdi ba don vi chidu cao. Vao giura nhurng nam 1950. khi truyen hinh tro thanh moi de doa giu chan khan gia xem rap d nha. cac nha lam phim Ho-li-ut lai tao ra duoc mo« sue hap dan mdi. bang viec dua ra loai man anh rong giong vdi trudng nhin cua con ngudi. Cac nha che tao H DTV hien dang dat hy vong vao l o a i' m a n anh xem de chiu hon. vdi tv le 16:9 nay. Cac chuyen gia chi ra rang, hinh anh H D TV nc c o k i c h thuos. ldn hon nhieu ma khong he bi kem chat lupng khi su dung luong t h o n g tin Ion g a p nam lan tren mot khuon hinh va do net cao hon nam lan. kem theo viec ap du ng am thanh k\ thuat so.
Language focus 5 NOUN CLAUSE 1. Definition Cac loai menh d6 hoat dong nhirdanh tir duoc goi la menh de danh tir (noun clause). \ 7 du I The op erator k n o w s what the ta rg et’s velocity is. what the ta rg e t’s velocity is co chuc nang giong nhu mot danh tir. tra loi cho cau hoi what d o es the op e ra to r know ? 2 . Structure 1. Trat tir tir trong cac me nh de danh tu la trat tu cua cau khang dinh. Khi lap mot menh de da nh tu, ta nen tao ra mot cau hoi, sau do chuyen cau hoi nay thanh dang cau k h i n g dinh va g iu lai dai tir nghi van lam lien tu noi hai me nh de. W h-q u estio n w ord (w ho. what, when...) + S + V (+...) 17 du 2 H o w m a n y lim itations does the vacuum tube h a v e ? We sh o u ld f i n d out how m a n y lim itations the vacuum tube has. 2. Neu cau hoi lap ra ma khong co dai tir nghi van (yes/no question), thi ta dung i f hoac w h eth er de lam lien tu noi hai me nh de. • if/w h eth er + S + V (+...) Vi du 3 Are they in terested in the p o w e r gain o f the am plifiers '.' We don't kn o w if/w h eth e r they are interested in the pow er gain o f the am plifiers. 3. Khi m e n h de danh tir la chu ngir trong cau va la mot loi nhan dinh (khong lien quan den hai loai cau hoi ke’ tren, thi men h d£ du a c bat dau bang that (that clause) • that + S + V7 (+ ...) \ 7 du 4 T hat the in ca n d escen t lam p has three elem ents, the envelope, the fila m e n t , a n d th e vacuum is a necessity. 4. Khi m e n h de th a t clause khong phai la chu ngu. ta co the luac bo that.
112 Tieng A nh chuyen nganh Dien ti/ - Vien thong \ i du 5 Edison discovered (that) the heat o f the filam ent caused the electrons to be freed from the solid matter o f the filam ent. 5. Doi vai nhung cau true that clause qua dai ta co the du ng chu ngur gia It trong mot cau true men vai y nghTa tuang duang. • It + to be + Adjective / \ o u n + that-clause \ i du ft That you must have oxygen f o r fire to exist was logical It w as logical that you must have oxygen f o r fire to exist 6. Qu a \ e m xet vai tro cua men h de danh tu. ta co the co nhun g phucmg an dich sao cho co the lam noi bat me nh de nh u la mot danh tu nhu sau: ( \ 7 du 3) C h u n g roi k ho ng b iet lieu ho cd q u a n lam d e n d o k h u e c h dat dong h a y khong. i\ i du 4 1 Viec m ot bong scji dot cd dii ba yeu rd. vo chifa. sen nung. va m di trudng chan khdng. la mdi dieu bar budc (plidi cot. i\ i du 5 1 Edison da p h d t hien ra rang nhiet cua sen nung Id nguxen nhan la n ; clu> cac dien nr dirge giai p h o n g ra khoi sen nung the ran.
L an guage focus 5 11:i 2. H o w arc electronic com po nents c o n n e c te d ? The circuit dia gram of an electronic device shows... 3. Wliat is the value o f each co m po n en t ? The circuit diagram of an electronic device shows... 4. Is the signal reflected sim ilar to the one which has been tr a n sm itte d /’ The c om par at or of a radar system tells... 5. H o w d o es a signal vary with tim e ? An oscilloscope shows... B. Use that clause to jo in the fo llo w in g groups o f statem ents to m ake longer sentences. T h e b eg in n in g o f each new sentence has been given. E.g: Edison's d e a fn ess p r o v id e d the m otivation fo r m an x o f his inventions. This was possible. It was possible that Edison's deafness provided the motivation for ma nv of his inventions. 1. So m u c h of the rapid development of electrical devices took place during the 19"' century. This fact is quite remarkable. It is ................................................................................................................................................... 2. Edison would be able to prevent the light bulb from overheating. Edison hoped this. It i s ..................................................................................................................................................... 3. Edison would invent a safe and inexpensive electric light. Edison a nno un ce d this. lull son ...........................................................................................................
114 Tieng A nh chuyen nganh Dien ttf - Vien thong 4. At the time Edison ex perimented on the incandescent lamp he did not understand Oh m' s law. This is surprising. It is..................................................................................................................................................... 5. Edison effect was explained by the thermionic emission o f electrons from the hot to the cold electrode. Scientists later determined this. Scientists
Unit 16 TELECOMMUNICATIONS SYSTEM The technology o f telecommunications has continued to advance rapidly ever since the invention of telegraph and telephone systems that revolutionized the means of commu nic ati ons about a century ago. Today, the electrical telecom mun ic at ion s system is regarded as the most economical means available for transmitting voice, facsimile, data, radio, or television signals. The most c o m m o n ly used te lecommunications system is a telephony com mun ic ati ons system where men are information sources as well as users, and telephones used as transmitters/receivers. Currently, the ma chine-run information a nnouncem ent service, characterized by the machine acting as information source and men serving as users, is in high de mand. In addition, machi ne- to -ma chi ne com mun ic ati ons such as data communicati ons are now in service. Co mm un icat io ns carried out through the interface between men and machines, and between machines, as in the case of the conventional methods, are expected to be come more popular. Toget he r with the conventional telecommunications services based on the telephone and telegraph systems independently run through the utilization o f the subscriber telephone network, an increasing numb er of highly sophisticated and powerful me an s such as data and video c om mu nic ati on s are being installed and operated. Digital transmission is employed in the te lecomm unication s system in order to achieve high reliability and because the cost of digital sw itching systems is muc h lower than the cost of analog systems. In order to use digital transmission, the analog signals must be subjected to a process of analog-to-digital conversion. (In data transmission this step is bypa ssed because the signals are already in digital form; most television, radio, and voice com mu nic ati on, however, use the analog system and must be digitized). In the earl) part of the 1960s, PCM (Pulse Code Modulation) metho d was successfully com me rci ali ze d, thus providing that digital transmission method was far more e co nomi cal than conventional analogue transmission method. Ever since, the digital switching systems run on the digital transmission system have been installed and operated widely.
116 Tieng A nh chuyen nganh Dien tu - Vien thong Researchers and engineers in the advanced countries are working hard to develop this type of digital c om mu nic ati ons network. Also available is the ISDN t Integrated Services Digital Network) where integrated services are provided with digitalized terminals. In addition, as the types of te le communications services offered become more varied, a wide range of terminal types, one of the three important parts of telecommunications network, namely, terminal, transmission, and switching facilities, are now used widely. Most existing public terminals are designed to be easily operated as much as possible, however some of them, called integrated terminals, are equipped with advanced features used for special services. Consequently, the formats of using c om mu nic ati ons will become more diversified, and also the efforts to develop technology adequate for those purposes will be made. (Text adapted from G eneral Introduction oj T elecom m unication T h e o ry by LG Information & C om m unications. Ltd. i Words and expressions advanced (adj) tien tien, phat trien characterize (v) bieu thi dac diem, dac trirng (cho) cost (n) gia thanh diversified (adj) phong phu, da dang effort (n) no li/c telecom m unications (nganh) vien thong facility (n) phi/dng tien facsimile (n) may fax feature (n) tinh nang interface (n.v) giao dien integrated tich hop, lien ket PCM (Pulse Code Modulation) dieu che xung ma regard (v) ~ as coi, cho (... la) reliability (n) do tin cay, tinh tin cay revolutionize (v) cach mang hoa sophisticated (adj) phuc tap, tinh vi terminal (n) (thiet bi) dau cuoi 1. M a i n idea W hich sta tem en t best expresses the m ain idea o f the text? W hy did yo u elim inatt the other ch o ices? 1. Terminals, transmission lines, and switching facilities are the three mosi import an c om pon ent s of a te le co mm un icat io n system.
Unit 16 117 2. A typical telecommunication system based on the telephony system is capable of transmitting various kinds of information and speech. 3. Based on the telephony system, a typical te le communication system, which is now in the process o f digitalization, is capable of transmitting diversified types of information. 2. Q uestions A n sw er the fo llo w in g questions. 1. What were the first devices used in telecommunication? 2. What is a typical telecommunication system capable of doing? 3. Why is digital transmission to be more widely used in telecommunication systems ,) 4. What is meant by PCM ? What is its function? 5. What characteristic of the ISDN is mentioned in the text? 3. U n d ersta n d in g the passage Decide w h eth er th e fo llo w in g statem ents are true or fa lse (TIF) by referring to the info rm a tio n in th e text. T hen m ake the necessary changes so that the fa lse statem ents becom e true. 1 In the telephony com mun icati on system, men are considered both information sources and users. 2 An increasing n um be r o f powerful means o f video and data c o m m un ic at io n are being installed and operated. 3 In data transmission, signals must be converted into the digital form before transmission. 4 W ith the introduction of PCM method, costs of transmission were greatly reduced. 5 Transmission lines are the most important component of a telecommunication svstem.