Phương pháp đo - kiểm tra truyền hình tương tự và số: Phần 1

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Phần 1 tài liệu Đo - Kiểm tra truyền hình tương tự và số trình bày các nội dung: Đo - Kiểm tra chất lượng truyền hình tương tự (đối tượng đo - Kiểm tra, hình ảnh và tín hiệu kiểm tra, các phương pháp đo - kiểm tra,...). Mời các bạn cùng tham khảo.

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Nội dung Text: Phương pháp đo - kiểm tra truyền hình tương tự và số: Phần 1

NGUYEN KIM SACH 4to • ► ■ ;; l i > 4 /+ * * ,^ o j - K I E i y i T R A T R U Y EN H IN H T U O N G T U it ii ’ ■ - V A S O u lu a llM _ nn'Xh W NrtOaOOW ..* H - S i sis ■' t in W IL C O X 10 nhA xuat ban khoa hoc VA KY THUAT
GS. TSKH. NGUYEN KIM SACH D O - K IE M T R A T R U Y E N H IN H T lfffN G T U V A S O (Measuring and Monitoring of Analog and Digital Television) C P N H A XUAT BAN K H O A H O C V A KY THUAT
MUC ■ LUC ■ Trang M UC L U C ............................................................................................................................................. 3 L(JI N O I D A U .................................................................................................................................... 17 Phan I DO-KIEM TRA CHAT LIK IN G TRUYEN HINH Tl/O NG TV Chuang 1. D O I TU O N G DO - K IE M TR A 21 1.1. M d d a u ............................................................................................................................21 1.2. C a c th 6 ng so chat lupng anh truyen h in h .............................................................22 1.2.1. Do choi va do ti/Ong p h a n ............................................................................ 22 1.2.2. Do ro ( n e t) ......................................................................................................... 23 1.2.3. Hinh anh co dien tfch Idn va do choi dong d e u .......................................24 1.2.4. M eo hinh h o c .....................................................................................................24 1.2.5. K hoang cach giCfa cac d o n g ........................ \ .............................................. 25 1.2.6. A nh phan xa (hinh b o n g ) ............................................................................... 25 1.2.7. N hieu va can n h ie u .......................................................................................... 25 1.2.8. D anh gia anh m a u ........................................................................................... 27 1.3. C a c thdng so tin hieu truye n h in h ........................................................................... 27 1.3.1. Tin hieu v id e o ....................................................................................................27 1.3.2. Tin hieu P A L ...................................................................................................... 27 1.3.3. Tin hieu N T S C ...................................................................................................28 Chircmg 2. H IN H AN H V A T IN H IE U K IE M TR A 29 2.1. Anh kiem t r a ...................................................................................................................29 2.1.1. A n h den tren nen trS n g ................................................................................... 29 2.1.2 A n h cac spc d e n -trS n g .................................................................................... 30 2.1.3. A nh ni/a den ntfa trS n g ................................................................................... 31 2.1.4. A nh kiem tra tan so trung b in h ..................................................................... 31 2.1.5. A nh kiem tra do ro d cac vung tan so khac n h a u .................................. 31
2.1. 6 . Anh kiem tra do rd theo chieu n g a n g ........................................................ 32 2.1.7. Anh kiem tra do on djnh cua m i/c d e n .............................*........................ 32 2.1. 8 . Anh kiem tra do tUOng p h a n ........................................................................ 33 2.1.9. Anh kiem tra tong h o p ................................................................................... 33 2.2. Tin hieu kiem tra .......................................................................................................... 35 2.2.1. Tin hieu kiem tra khdng ttf d o n g ................................................................. 35 2.2.2. Tin hieu kiem tra tu d o n g .............................................................................. 38 2.2.2.1. Tin hieu VITS dong 1 7 ....................................................................39 2 2 2 2 . Tin hieu VITS dong 1 8 ................................................................... 41 2.2.2.3. Tin hieu VITS dong 330 ................................................................ 43 2.2.2.4. Tin hieu VITS dong 331 ................................................................. 44 Chin mg 3. CAC PH l/O N C PHAP DO - K IK M TR A 45 3.1. PhifOng phap danh gia chu q u a n ............................................................................ 45 3.2. Phuong phap do-kiem tra cac th 6 ng so tin hieu video (danh gia khach q u a n )................................................................................................46 3.2.1. Cac dieu kien do thiet bi v id e o .....................................................................47 3.2.2. Do m ile tin hieu v id e o .....................................................................................47 3.2.3. Do dac trung tan s o ........................................................................................ 48 3.2.3.1. Do dac trung bien d o ....................................................................... 48 3.2.3.2. Do dac trung p h a ...............................................................................52 3.2.3.3. Quan he giQa dac trung tan so va x u n g .................................... 52 3.2.4. Do dac trung x u n g ........................................................................................... 58 3.2.4.1. Do thdi gian x u n g ..............................................................................59 3.2.4.2. Do thdi gian sudn xung len / x u o n g .............................................59 3.2.4.3. Do meo dinh xung va m eo dinh xung ci^c dai so vdi ta rn .... 62 3.2.4.4. Do thdi gian tru y e n ........................................................................... 64 3.2.4.5. Do jitte r................................................................................................. 65 3.2.5. Do bang tin hieu do “ S in 2 + xung chir nhat” .............................................. 66 3.2.5.1. D ac trung cua xung “ S in2" .............................................................. 66 3.2.5.2. D anh gia m eo tren tin hieu “sin 2 + xung chuf nhat” .................70 3 2 .5 .3 . Khuon do he so K ............................................................................. 72 3.2.5.4 Do dac trung bien do va pha trong dai tan tai m a u ................75 3.2.5.5. D anh gia m eo bang tin hieu sin 22 0 T ...........................................76 3.2.6. Do m eo phi t u y e n ............................................................................................. 80
MUC LUC 5 3.2.6.1. Do m eo phi tuyen tin hieu c h o i..................................................... 80 3 .2 . 6 .2. Do m eo phi tuyen tin hieu m a u ....................................................84 3.2.7. Do nhieu va can n h ie u ................................................................................... 8 8 3.2.7.1. Do n h ie u ........................................................................................ .■■■88 3.2.7.2. Do can n h ie u ..................................................................................... 95 3.2.8. Do phan xa va suy giam do khdng phoi hop trd k h a n g .......................97 3.2.8.1. Do do suy giam do khOng phoi hop trd khang bSng cap tre .......................................................................................98 3.2.8.2. Do suy giam kh&ng phoi hop trd khang bang mach cau do W h e a ts to n e ........................................................................................ 99 ChUamg 4. DO - KIEM TRA CAC I HIET BI TRUYEN HINH 101 4.1. D o -ki^m tra k§nh c a m e ra .......................................................................................101 4.1.1. M eo tuyen ti'nh va phi tu y e n ....................................................................... 102 4.1.2. Ti so tin hieu tr£n nhieu S /N ...................................................................... 102 4.1.3. Do m eo hinh hoc, meo phi tuyen m ach q u e t........................................102 4.1.4. Do do dong quy (c o n v e rg e n c e )................................................................ 104 4.1.5. Do can nhieu m ang dien ISn tin hieu v id e o ............................................106 4.2. Do C C D ........................................................................................................................ 108 4.2.1. Do nhay va dac trung chieu s a n g .............................................................108 4.2.2. Do phan g ia i................................................................................................... 109 4.2.3. TT so tin hieu trfen n h ie u ............................................................................... 1 10 4.2.4. M eo h]nh h o c .................................................................................................. 110 4.2.5. Q uan tfnh va do luu anh (la g ) .................................................................... 110 4.2.6. Do dong deu cua nen va “vet o ch a y” .................................................... 1 10 4.2.7. D a c trung p h o ..........:...................................................................................... 111 4.3. Do te le c in e .................................................................................................................. 112 4.4. D o -kiem tra V T R ........................................................................................................ 115 4.4.1. K iem tra so bo m ay ghi h in h ...................................................................... 116 4.4.2. Do m eo tuyen t fn h ......................................................................................... 1 1 7 4.4.3. M eo phi tu y e n ................................................................................................. 118 4.4.4. M eo hinh hoc va do khdng on djnh hinh a n h ........................................ 120 4.4.5. Do can nhieu va ti so S /N ............................................................................121 4.4.6. B ang kiem tra dien tC/ va bang d o ............................................................. 1 2 3 4.5. Do bo ma hoa P A L ......................................................................................................
6 0 0 - KIEM TRA TRUYEN HiNH TUONG TtfVA SO 4.6. B o-kidm tra thiet bj dudng tru y e n .........................................................................129 4.6.1. Kiem tra hieu qua hoat dong cua m ach 6 n dinh m dc d e n ............... 129 4.6.2. Kiem tra do suy hao khdng phoi hop trd k h a n g ................................... 130 4.6.3. Bo do tham thau tin hieu n g o a i................................................................. 130 4.6.4. Bo do tre .......................................................................................................... 131 Chuang 5. DO - KIEM TRA Dl/CJNG TRUYEN VA MAY PH AT HINH 133 5.1. Md d a u ........................................................................................................................ 133 5.2. B o -ki^m tra dudng truyen ngoai thdi gian phat h in h .......................................136 5.2.1. Xac djnh mdc tin hidu dudng tru y e n ....................................................... 137 5.5.2. Cac thdng so dudng truye n tin hieu v id e o .............................................137 5.3. Bo trong thdi gian truyen va phat h in h ................................................................ 148 5.3.1. PhUdng phap d o ............................................................................................148 5.3.2. Bo vdi cac tin hieu tr§n cac dong kiem t r a ........................................... 148 5.4. Bo-kid’ m tra may phat h in h .....................................................................................155 5.4.1. Md d a u .............................................................................................................155 5.4.2. B o-kiem t r a ..................................................................................................... 156 Chmmg 6. DO • KIEM TRA MAY THU HINH 159 6.1. Md d a u .........................................................................................................................159 6 .2 . C ac dieu kien do-kiem t r a ...................................................................................... 159 6.3. B o-kiem tra khai q u a t.............................................................................................. 162 6.4. B o-kiem tra m ay thu theo m ile tin hieu v a o ...................................................... 162 6.4.1. G idi thieu c h u n g ............................................................................................ 162 6.4.2. Bo do nhay kdnh v id e o ................................................................................ 163 6.4.3. Bo m dc tin hieu vao cOc d a i...................................................................... 165 6.4.4. Bo dac trung tTnh m ach A G C ..................................................................... 165 6.4.5. B o-kiem tra phoi hop trd khang tai dau vao m ay thu h in h ............... 166 6.5. Anh hudng cua tin hieu can n h ie u ........................................................................168 6.5.1. G idi th ie u ..........................................................................................................168 6.5.2. B o-kiem tra do chon lo c ............................................................................... 168 6.5.3. B o-kiem tra can n h ie u ..................................................................................172 6.5.4. B o-kiem tra can nhieu do dieu che c h e o ............................................... 172 6.5.5. B o-kiem tra can nhieu do dieu che qua l a i ............................................173 6.5.6. B o-kiem tra nhieu tu bdn trong m ay t h u .................................................174 6.5.7. B o-kiem tra can nhieu td nguon d ie n .......................................................174
MUC LUC 7 6 .6 . Do chat lupng d 6 ng bo va q u e t ........................................................................... 174 6 .6 . 1 . G idi th ie u ........................................................................................................ 174 6.6.2. D o -ki^m tra pham vi dong b o ................................................................... 6.6.3. D o-kiem tra dSc trung pha cua m ach quet d o n g ................................. 176 6.6.4. D o-kiem tra chat luqng cac dong xen k e ...............................................1 77 6.6.5. D o -ki^m tra do djch dong bo d o n g ..........................................................17 8 6 .6 .6 . Do m eo hinh h o c .......................................................................................... 179 6.6.7. D o-kiem tra sai so dong q u y ......................................................................183 6.7. D o -ki^m tra dac trung dien-quang (kin e sco p e )................................................ 183 6.7.1. G idi t h ie u .........................................................................................................183 6.7.2. D o -kiem tra do choi cue d a i....................................................................... 184 6.7.3. D o-kiem tra do tUOng phan cOc d a i..........................................................184 6.7.4. Do sai so cSn b&ng tr& ng............................................................................185 6.7.5. Do do tinh khiet cua anh s a n g .................................................................. 186 6 .8 . D o-kiem tra do trung th ^ c khdi phuc kSnh v id e o .............................................187 6.8.1. G idi t h ie u ......................................................................................................... 187 6.8.2. Dung tin hieu “sin 22T + xung chuf nhat” de kiem tra k§nh c h o i....... 187 6.8.3. D ung tin hieu “sin 220T + xung chQ nha t” de kiem tra kenh m a u .....187 6.8.4. D ung tin hieu xung chuf nhat 50H z de kiem tra k§nh c h o i............... 188 6.8.5. D ung tin hieu xung chuf nhat 50H z de kiem tra k§nh m a u ................189 6 .8 .6 . Do m eo thanh phan m ot chieu cua tin hieu c h o i.................................189 6.8.7. Do m eo thanh phan m ot chieu trong kenh m a u ..................................190 6 .8 .8 . Do th d i gian tre giufa tin hieu choi va m a u .............................................191 6.8.9. Do m eo phi tuyen trong k£nh c h o i........................................................... 192 6.8.10. Do m eo phi tuyen trong k&nh m a u .........................................................193 Chuang 7. THIET BI DO ■ KIEM TRA 195 7.1. Md d a u ..........................................................................................................................195 7.2. G enerator tao dien ap s in ....................................................................................... 1 96 7.2.1. G enerator tao tin hieu video 10KHz 1 5 M H z.......................................196 7.2.2. G enerator cao tan dieu che v id e o ............................................................. 1 97 7.3. W obbu lator truye n h in h ........................................................................................... 1 93 7.3.1. W obbu lator cho v id e o ..................................................................................... gg 7.3.2. V ideo scope va thiet bj ph&n tich bien tan c u t ....................................... 1 9 9
8 0 0 - KlfiM TRA TRUYEN HiNH TUONG TUVA S6 7.4. G enerator tao tin hieu do v id e o ............................................................................ 200 7.4.1 NguySn ly tao cac tin hieu d o ....................................................................200 7.4.2. Nhom m ach tao tin hieu d o ........................................................................ 202 7.5. Generator tao anh kiem tra dien tuf...................................................................... 204 7.5.1. Mach dien tao anh kiem tra d e n -trS n g ....................................................204 7.5.2. Mach dien tao anh kiem tra van n a n g .................................................... 206 7.6. Generator tao cac sqc m a u ................................................................................... 207 7.6.1. Cac sqc m a u ................................................................................................. 207 7.6.2. Mach tao tin hieu cac sqc m a u ................................................................. 209 7.7. Generator tao n h ie u ................................................................................................ 210 7.8. Monitor va m ay thu kiem tra truyen h in h ........................................................... 210 7.8.1. M onitor m a u ........................................................................ ........................... 210 7.8.2. M ay thu kiem tra truyen h in h .....................................................................213 7.8.3. Mot so loai m onitor va m ay thu k ilm tra truyen h in h ......................... 214 7.9. May hien song truyen h in h .................................................................................... 217 7.9.1. M ay hien song kiem t r a .............................................................................. 218 7.9.2. Mach dien may hien song kiem tra ..........................................................220 7.9.3. Mach dien may hien song do truyen h in h ..............................................221 7.10. V ectorscope..............................................................................................................222 7.10.1. Nguy&n ly hoat d o n g .................................................................................222 7.10.2. Cac loai vectorscope va waveform m o n ito r........................................226 7 .1 1 . S e cam sco pe.............................................................................................................226 7.12. V 6 n ke chon Iqc.......................................................................................................228 7.13. Do n h ie u .................................................................................................................... 229 7.14. Thiet bi do meo vi s a i............................................................................................. 231 7.15. Cau do suy giam do kh 6 ng phoi hop trd k h a n g .............................................233 7.16. T hiet bi do dac trung d ie n -q u a n g ........................................................................234 Chucmg S. T I / DONG DO - K IE M I RA TR UYEN H IN H 239 8 . 1 . To dong phan tich dang tin h ie u ........................................................................... 239 8.1.1. Cac phuong phap do to dong true t ie p ................................................... 241 8.1.2. Bien doi tin hieu do qua A D C .................................................................... 246 8.2. Truyen dQ lieu do trong khoang cach x a ............................................................249 8.3. He thong do-tin h o c ...................................................................................................250 8.4. Bo thiet bj do chat lUOng video V M 700T (T e k tro n ix )....................................... 254 8.5. He thong do video VSA ( R & S ) .................................................................. 257
MUC LUC 9 Phan I I BO-KIEM TRA TRUYEN HINH SO C huang 9. CO SO TRIJYf’N HINH SO VA VAN DE DO - KIEM TRA 261 9.1. M d d a u .........................................................................................................................261 9.2. Co sd ve s o ................................................................................................................ 261 9.2.1. Tin hieu thanh phan va tin hieu t 6 ng hpp ............................................ 261 9.2.2. Lay m au va lupng td h o a ............................................................................262 9.2.3. C ac tiSu chuan video s o ............................................................................. 263 9.2.3.1. Parallel com ponent digital (tin hieu thanh phan 267 so song s o n g ) .................................................................................264 9.2.3.2. Parallel com posite digital (tin hieu tong hpp so' song s o n g ) ............................................................................ * ..2 6 5 9.2.3.3. Tin hieu so com ponent, m an hinh rong 1 6 :9 ......................... 267 9.2.4. Video so noi tie p ............................................................................................ 267 9.2.5. Bien doi toe do va djnh d a n g .....................................................................269 9.3. A udio s d .......................................................................................................................270 9.3.1. D inh dang dQ lieu audio theo A E S /E B U ..................................................270 9.3.2. N hung a u d io ...................................................................... ............................ 272 9.3.3. K hong gian dQ lieu p h u ................................................................................ 272 9.3.4. T ao dinh dang dQ lieu p h u ..........................................................................274 9.3.5. A udio nhung c 0 b a n ...................................................................................... 275 9.3.6. A udio nhung md r o n g ...................................................................................276 9.3.7. Kich th u d c buffer cua m ay t h u ...................................................................278 9.3.8. Tao audio theo A E S /E B U ........................................................................... 280 9.4. He thong phan cQ ng................................................................................................. 280 9.4.1. C a p .....................................................................................................................280 9.4.2. O noi (c o n n e c to r)........................................................................................... 281 9.4.3. Patch panels (pand m a n g ).......................................................................... 281 9.4.4. T h ie t bj dau c u o i.............................................................................................281 9 .4 .5 . Cap va connector cho audio s d .................................................................282 9.4.6. Phan phoi tin hieu, tao lai xung dong h o ................................................282 9.4.7. Phan thdi gian cho he th o n g .......................................................................283 9.5. Kiem tra va d o .............................................................................................................285 9.6. Do tin hieu so noi tie p ............................................................................................... 287 9.6.1. Do dang s o n g ..................................................................................................287 9.6.2. Do thdi gian tin hieu video sd noi tie p .................................................. 289
10 DO - KIEM TRA TRUYEN HINH TlfONG T l/V A SO 9.7. Dinh nghla va tach lo i...............................................................................................291 9.7.1. Dinh nghla sai s o ...........................................................................................292 9.7.2. Dinh lapng sai s o ...........................................................................................293 9.7.3. C ac he thong truye n dan video so trong s tu d io ................................... 294 9.7.4 Do B E R .............................................................................................................297 9.7.5. Phuong phap do sai so trong truye n h in h .............................................. 298 9.7.6. D q bao he th o n g ............................................................................................ 299 9.8. Hieu Qng jitter va d o .................................................................................................301 9.8.1. Jitter trong cac tin hieu so noi tie p ........................................................... 301 9.8.2. Do jitte r .............................................................................................................304 9.9. Kiem tra he th o n g ......................................................................................................306 9.9.1. Kiem tra kich hoat (stress te s tin g )........................................................... 306 9.9.2. Mien ki£m tra SDI (SDI C heck F ie ld )...................................................... 307 9.9.3. NRZI xao tr o n .................................................................................................307 9.9.4. Tin hieu "ben h” , m ien ki£m tra S D I.......................................................... 309 Chitamg 10. DINH NGHIA, KHAI NIEM CAC THONG SO DO - KIEM TRA SO 311 10.1. Gidi th ie u ................................................................................................................... 311 10.2. M ot so dinh nghia .................................................................................................. 311 10.2.1. Goi truyen ro n g ............................................................................................ 311 10.2.2. Vecto l o i ........................................................................................................ 312 10.2.2.1. So sanh M ER va E V M ............................................................... 313 10.2.2.2. Ket luan ve MER va E V M ......................................................... 314 10.3. D ac tinh ky thuat cua tin hieu do 6 bo dieu che D V B -T .............................. 314 10.3.1. G idi th ie u ....................................................................................................... 314 10.3.2. Tin hieu ngo v a o .......................................................................................... 314 10.3.3. Cac mode d o ................................................................................................ 315 10.3.4. Cac diem d o ..................................................................................................316 10.3.5. Dinh dang file doi vdi xen ke dQ lieu gia la p .......................................316 10.4. Cdng suat RF/IF (“song m a n g ").......................................................................... 320 10.5. MQc n h ie u ...................................................................................................................321 10.6. Nang lUpng tr§n bit (E b) ......................................................................................... 321 10.7. TT so C/N va Eb/N 0 ................................................................................................... 322 10.8. Cac phep do thtfc t e ................................................................................................322 10.9. Xac suat loi cua Q A M ............................................................................................. 325
muuLUC 10.10. X ac suat loi cua Q P S K .......................................................................................326 10.11. Xac suS't loi sau giai ma V ite rb i....................................................................... 327 10.12. Xac suat loi sau giai ma R S ............................................................................. 327 10.13. BER Lfng vdi gia trj C/N doi vdi D V B -C .......................................................... 328 10.14. BER tUdng Cfng C/N trong D V B -S ....................................................................329 10.15. C ong nhieu vao tin h ie u ......................................................................................330 10.16. Ijd c lUdng biSn nhieu NM (Noise Margin) bang phUOng phap 331 p h ^n ti'ch thong k 6 tr£n chom s a o .................................................................. 331 10.17. Do nhieu pha RF dung m ay phan ti'ch ph
12 OO - KIEM TRA TRUYEN HINH Tl/ONG TU VA SO 11.2. NguySn tSc kiem tra v id e o ....................................................................................352 1 1 .2.1. C ac Idp ch ifc n a n g ...................................................................................... 352 11.2.2. C hat lUdng v id e e ..........................................................................................355 11.3. K ilm tra chat Iddng a n h ....................................................................................... 357 11.3.1. K i^m tra chu q u a n ...................................................................................... 357 11.3.2. K iim tra khach q u a n .................................................................................. 359 1 1 .3.3. Ap dung he thong H V S ..............................................................................361 11.3.4. Tiep can he thong kiem tra khach q u a n .............................................. 363 11.4. Thiet bi do chat lupng a n h ....................................................................................365 Chuomg 12. CAC THONG SO DO - K IK M TRA HE THONG DVB-C/-S/-T 367 12.1. He thong D V B ......................................................................................................... 367 12.2. Do va phan ti'ch dong truyen M P E G -2 ..............................................................369 12.2.1. Md d a u ...........................................................................................................369 12.2.2. Cac th 6 ng so danh g i a ..............................................................................369 12.3. Cac th 6 ng so d o -k ilm tra trong D V B-S va D V B -C .......................................376 12.3.1. Kha nang he th o n g ..................................................................................... 376 12.3.2. Kha nang dudng tru y e n ............................................................................ 377 12.3.3. BER trudc bo giai ma R e e d -S o lo m o n ...................................................377 12.3.4. Ghi chep cac stf kien l o i ........................................................................... 378 12.3.5. Do trupt jitter va do chinh xac xung dong ho sym bol ..................... 379 12.3.6. C dng suat tin hieu R F /IF ........................................................................... 379 12.3.7. C dng suat n h ie u .......................................................................................... 380 12.3.8. Dem so bit loi sau bo giai ma R e ed -S o lo m o n .................................... 380 12.3.9. Phan ti'ch tin hieu I Q ................................................. \ ................................380 12.3.9.1. Md d a u .............................................................................................380 12.3.9.2. Ti so loi dieu che MER (m odulation error ra tio ).................. 381 12.3.9.3. Loi m uc tieu he thong STE (S ystem T arget E rro r)............382 12.3.9.4. T rie t song m ang CS (carrier s u p p re s s in g ).......................... 383 12.3.9.5. M at can bang bien do A l (am p litud e im b a la n c e )................383 12.3.9.6. Loi vuong pha QE (Q ua dra ture E rro r)................................... 384 12.3.9.7. Loi d u th i/a m uc tiSu RTA (R esidual T arget E rro r)............ 385 12.3.9.8. Can nhieu li§n ket C l (C ohe re nt in te rfe re r)........................ 385 12.3.9.9. T ru p t pha PJ (phase jitte r)...............................................’ .........386 12.3.10. Can nhieu (In te rfe re n c e )..........................................................................387
12.4. C ac thdng s 6 do dung ridng cho cap quang (D V B -C ).................................388 12.4.1. Bidn bao ve nhieu (noise m a rg in ).......................................................... 388 12.4.2. J d c luqng bidn n h ie u ................................................................................. 388 12.4.3. Kiem tra bidn chat lupng tin h ie u ........................................................... 388 12.4.4. Do suy giam nhieu tuong duong END (E quivalent N oise D e gra dation )...............................................................389 12.4.5. Do gia trj BER Lfng vdi Eb/N 0 ...................................................................390 12.4.6. N hieu pha cua song mang R F ................................................................ 391 12.4.7. D ap dng bidn do, pha va xung cua kdnh tru y e n ............................... 391 12.4.8. SQ p ha t xa ngoai dai th d n g ...................................................................... 391 12.5. C ac thdng sd do dung ridng cho ve tinh ( D V B -S ) ........................................392 12.5.1. BER trUdc khi giai ma V ite rb i...................................................................392 12.5.2. Do BER dng vdi Eb/N 0 ...............................................................................392 12.5.3. Pho IF ..:..........................................................................................................393 12.6. C a c thdng so do dung cho he thdng tru ye n hinh sd m at dat (D V B -T ).... 393 12.6.1. Do chinh xa c tan sd R F ............................................................................ 395 12.6.2. Tfnh chon Iq c ................................................................................................396 12.6.3. Pham vi tQ dong dieu khien tan sd (A F C )........................................... 396 12.6.4. N h ieu pha cua cac bo dao dong n o i..................................................... 396 12.6.5. C o n g suat tin hieu R F /IF ........................................................................... 397 12.6.6. C o n g suat n h ie u .......................................................................................... 398 12.6.7. Pho RF va I F ................................................................................................ 398 12.6.8. Do nhay m ay thu / dai dong doi vdi kenh G a u s s ia n ........................ 399 12.6.9. Do suy giam nhidu tUdng duong (E N D )............................................... 399 12.6.10. D a c trung tuyen tinh (suy giam v a i) .................................................... 399 12.6.11. H ieu su a t ve cdng s u a t............................................................................400 12.6.12. Can nhieu lien ket (C oherent In te rfe re r)............................................ 400 12-.6.13. Do BER dng vdi gia trj C/N bang cach thay doi cd n g su a t m ay p h a t ..................................................................................400 12.6.14. BER dng vdi gia trj C/N bang cdch thay doi cdng suat nhieu G a u s s ia n ...................................................................................................... 401 12.6.15. BER trUdc bo giai ma V ite rb i................................................................. 401 12.6.16. BER trade bo giai ma R e e d -S o lo m o n ................................................ 4 0 2
12.6.17. BER sau bo giai ma R e e d -S o lo m o n ................................................... 403 12.6.18. Phan ti'ch tin hieu I Q .................................................................................403 12.6.18.1. Md d a u .......................................................................................... 403 12.6.18.2. TT so loi dieu che M E R .............................................................404 12.6.18.3. Loi m uc tifeu he thong S T E .................................................... 405 12.6.18.4. Triet song m ang C S ..................................................................406 12.6.18.5. Mat can bang bi§n do A l ......................................................... 406 12.6.18.6. Loi vudng pha Q E ..................................................................... 407 12.6.18.7. TrUpt pha P J ............................................................................... 407 12.6.19. Tre toan bo tin hieu OSD (O verall Signal D e la y)............................. 409 12.6.20. Do cudng do tru d n g ..................................................................................409 12.6.21. Do dap lin g xung cua k& n h .................................................................... 411 Chtf
P 1.1.5. Q uet xen ke (i) so vdi q ue t lign tu c ( p ) ................................................ 428 P 1.1.6 . Tach fram e que t liSn t u c .......................................................................... 428 P 1.1.7. C ac dinh dang tin hieu truye n hinh so hien n a y ................................428 P 1.2. C ac dinh dang nen dung 6 s tu d io ..................................................................... 436 P 1.2.1. M JPEG va M P E G ...................................................................................... 436 P 1.2.2. Dinh dang nen D V ...................................................................................... 436 P 1.2.3. D olby E audio nen dung cho s tu d io ...................................................... 436 P 1.3. N en audio va video s o ..........................................................................................437 P 1.3.1. Nen video M P E G -2 ....................................................................................437 P 1.3.2. Nen D V ..........................................................................................................444 P 1.3.3. Nen M P E G -4 ................................................................................................445 P 1.3.4. N en audio bang M P E G ............................................................................ 446 Phu lu c 2. DO - K IE M TR A TR UYEN H IN H SO 455 P 11.1. C ac Idp th i/ nghiem v id e o .................................................................................. 455 P 11.1.1. D jnh nghla chat lupng v id e o ...................................................................455 P 11.1.2. Tin hieu va chat lupng a n h ..................................................................... 455 P 11.1.3. Do chat luo'ng a n h ..................................................................................... 456 P II.2. C ac phUdng phap Test (chat lupng tin hieu) truyen th o n g ....................... 456 P 11.2.1. C ac yeu to anh hudng l§n chat lupng v id e o ......................................456 P II.2.2. S uy giam chat lupng do n e n ...................................................................457 P II.2.3. Do chat lupng a n h ..................................................................................... 457 P II.2.4. C a c Idp do khach q u a n ............................................................................458 P 11.2.5. N guon day d u ..............................................................................................458 P II.2 . 6 . T ach dac tr u n g ........................................................................................... 458 P II.2.7. T ach A rtifa c t................................................................................................ 459 P II.2 . 8 . M SE (sai so trung binh binh p h U d n g ).................................................. 459 P II.2.9. PhUdng phap PQR (P icture Q uality R a tin g )......................................459 P 11.2.10. JND (Just N oticeable D ifferences - sd chenh lech vi/a m di nhan b ie t)......................................................460 P 11.2.11. He thdng ph&n tfch chat lupng anh PQA 2 0 0 ................................. 461 P 11.2.12. Phuong phap PQM (P icture Q uality M e a su re m e n ts)................... 465 P 11.2.13. Kiem tra Q oS (Q uality of Service) theo chuong trin h ....................466
16 P II.3. P h^n ti'ch Protocol M P E G ...................................................................................467 P 11.3.1. Phan ti'ch thdi gian tri hoan M T S .......................................................... 467 P II.3.2. Bo giai ma m uc ti£u cua he t h o n g ...................................................... 471 P II.4. Kiem tra D V B ......................................................................................................... 472 P II.5. G enerator M T S ......................................................................................................473 c A c c h i T t i k n g a n h v i e t t A t ....................................................................................... 475 r A l LIE U T H A M K H A o 479
LOI NOI DAU C ung vdi sd phat trien nhanh chong cua cac he thong truyen hinh, cdng nghe do-kiem tra chuydn dun g truyen hinh cung dupe phat trien. T hdi lUdng cac chUOng trinh truye n hinh dUdc phat song ngay cang tang (18 -s- 2 0 gid / ngay) doi hoi phai co cac phUOng phap td don g do-kie m tra he thong truyen hinh ngay trong thdi gian phat hinh (vf du VITS - Video Insertion Test Signal). B e danh gia chat lUdng he thdng truyen hinh (td khctu san xu a t chUOng trinh, truyen dan den phat song trdn m at dat va qua ve tinh), can phai co cac phuong phap do-kiem tra (do-kiem tra chu quan va khach quan) va he thdng cac th ie t bj do phu hop cho truye n hinh tuong td va sd. C ac phep do-kiem tra tru ye n hinh tuong tp co con sd dung dude cho viec do-kiem tra truyen hinh sd hay khong ? C ac loai thiet bj do-kie m tra hien dai ngay nay da dat den m dc do nao ? Q uyen “D o -kie m tra truyen hinh tuong tp va sd" se giai dap m ot phan noi dung cua cac van de trdn. Tai lieu gom 2 phan vdi 13 chuong va phan phu luc (phu luc 1 va 2 tom ludc bang hinh anh ve tru ye n hinh so, van de do-kiem tra sd): P h an 1. B o -kie m tra truye n hinh tuong td Chu'dng 1: D oi tUOng do-kie m tra Chuang 2: Hinh anh va tin hieu kiem tra Chu'dng 3: C a c phuong phap do-kiem tra Chu’d ng 4: B o -k ie m tra cac thiet bj truyen hinh Chuang 5: B o -k ie m tra dudng truyen va m ay phat hinh ChUdng 6: B o -k ie m tra m ay thu hinh Chu’d ng 7: T h ie t bj do kiem tra ChUdng 8: Td don g do-kie m tra truyen hinh P h a n 2. B o -k ie m tra truye n hinh so ChUdng 9: Co sd tru ye n hinh sd va an 1e do-kie m tra ChUdng 10: B |nh nghTa, khai niem cac thdng sd do -kie m tra sd Chu'dng 11: B o chat lu'dng hinh anh trong cac he thdng truye n hinh sd Chu'dng' 12: C a c thdng sd do-kiem tra trong he thdng D V B -C /-S /-T Chu'dng 13: C a c th ie t bi do-kie m tra truyen hinh so.
18 Tai lieu chuye n khao nay co the giup ban doc tim hieu, nghign cu u va ung dung do-kiem tra truyen hinh (tuong to va so), n thich hop cho ky sU. can bo ky thuat, smh vien nganh D ien tu - Vien thong, dac biet la cac ky su lam viec trong nganh Truyen hinh - Vien thOng. Tuy da co nhieu co g^ng, song chac chan cuon sach van con co th ie u sot C h iin g t 6 i mong ban doc dong gop y kien. Thu gOp y xin gCfi ve Nha xuat ban KH&KT, 70 Tran Hung Dao. Ha Noi. TP. Ho C h i Mmh, Ngay 1 thang 10 ndm 2002 T a c gi£
DO - KIEM TRA CHAT Ll/ONG ■ TRUYEN HINH TUONG TU ■
Chuang I DOI TUONG D O - KIEM TRA 1.1. M d €>AU C h at iifpng hinh anh va am thanh tai m ay thu hinh phu thuoc vao chat lupng ky th u a t cua he thong thiet bj truye n hinh t i/ cam era, VTR, dung hinh, th ie t bj truye n dan, m ay phat hinh cho den m ay thu hinh. D o-kiem tra (m easurem ent-m onitoring) cho phep danh gia dupe chat lupng hoat dong cua toan bo he thong thiet bi truyen hinh. Trong trUOng hQD giam chat lUQng (co m eo), do-kiem tra se cho phep xac djnh dU0c cac sai lech (hoac hu hong) cu the? cua ti/ng khAu th ie t bi, do do kjp th d i hieu chinh, thay the th ie t bi de dam bao chat lupng hinh anh va Sm thanh. C a c phuong phap do-kie m tra thiet bj truyen hinh dua tr§n dac trung cua tin hieu truye n hinh. Tin hieu truye n hinh la loai tin hieu khong doi xUng (ky thuat tuong tu), bao gom thanh phan xoay chieu va m ot chieu. Tin hieu hinh (video) thudng khdng phai la dang sin, pho tan cua no dupe gidi han, phu thuoc logi ti