Truyen hinh

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<ul><li> 1. 1. Nguyn tc thu pht 3 mu 2. Kho st tn hiu chi ER, EG, EB, EY, tn hiu mu </li></ul> <p> 2. 1.1.1. u l s khc bit? Tt c cc nguyn tc ca truyn hnh en trng u c tn dng truyn hnh mu im khc bit - Truyn hnh en trng: truyn i tn hiu chi,tn hiu ting v cc tn hiu ng b dng,mnh - Truyn hnh mu: ngoi 4 thng s trn cn phi truyn i cc thng s v mu sc ca tng im nh 3. 1.1.2. Cn thu nhng thng s no? Cc thng s v mu sc c xc nh r rng nu bit c cc t l pha trn R,G,B ca cc mu tng ng R,G,B (da vo nh lut v trn mu). R : chi G, : chi l cy B : chi lam 4. 1.1.3. Lm th no thu c cc thng s ? Phi chia ph ra lm 3 gii ph mu R,B,G v dng 3 n vidicon d o bin trung bnh ca 3 qung ph ring R ( chi ), G ( chi l cy), B ( chi lam) 5. 1.1.4. Qu trnh thu mu din ra nh th no? 6. 1.2.1. Nguyn l ti to nh mu C th ti to nh mu t 3 n hnh en trng vi cht ph gia c thm vo lp quang lm cho 1 n c th pht mu , 1 n pht mu xanh l v 1 n pht mu lam S dng cc thnh phn in p R,G,B iu khin cc n tng ng sau cho qua h thng lng knh gip nh sng t c 3 n n mt cng 1 lc 7. 1.2.1. Nguyn l ti to nh mu 8. 1.2.2. Qu trnh ti to nh mu din ra nh th no? 9. 1.2.2. Qu trnh ti to nh mu din ra nh th no? 10. 1.3.1. Ti sao phi m bo tng thch? c rt nhiu my thu hnh en trng tn ti trc + l do kinh t =&gt;yu cu: + my thu en trng: lun thu c en trng ngay c khi chng trnh pht l mu + my thu mu: thu mu khi chng trnh pht l mu v thu c en trng khi chng trnh pht en trng 11. 1.3.2. Lm th no m bo tng thch? Buc phi pht i thnh phn EY nh ca en trng, cng vi l ER-EY;EB-EY rng ca 1 knh truyn hnh mu phi bng rng ca 1 knh truyn hnh en trng bng cch ci tn hiu mu vo ph tn cao ca knh chi ri mi truyn i 12. 1.3.3. Ti sao phi ci tn hiu mu vo ph tn cao ca knh chi ri mi truyn i? Nng lng ca tn hiu chi ch yu tp trung vng tn thp nn cn dch tn hiu mu ln ph tn cao gim nhiu 13. 1.3.4. Ti sao khng truyn trc tip ER;EG;EB? Vic truyn trc tip ng thi cc tn hiu ER;EG;EB i hi di thng ca h thng truyn hnh qu rng khng tha mn yu cu kt hp C th ly ra ER,EG,EB t cc tn hiu hiu mu 14. Uv (en trng) Uv mu C1 C2 f(Hz) SMP FM m thanh FM m thanh f(Hz) EY EY 15. 2.1.1. Th no l m ha? L qu trnh to ra cc tn hiu EY;C1;C2 v chn C1;C2 vo cng 1 knh sng vi EY (mc ch nhm m bo tnh tng thch) C1: l ER-EY sau khi iu ch C2: l EB-EY sau khi iu ch 16. 2.1.2. M ha din ra nh th no? Mch ma trn iu ch fsc + Tn hiu truyn hnh mu EG EB EY ER Cng tr in p theo t l nh 17. 2.2.1. Gii m din ra nh th no? Mch ma trnTch sng Lc di Tn hiu hnh mu EG EB EY ER -EY Ti CRT Tch tn hiu mang mu cao tn ra khi t/h chi 18. Trong vic chn tn hiu mu vo tn hiu chi c 1 vng tn s tn ti c t/h chi v cc t/h mu=&gt; xuyn ln Vn chn sng mang mu v phng php iu ch ntn gim thiu ti a xuyn ln c quy nh bi cc h mu(NTSC;PAL,SECAM). Tuy nhin khng c h no t u im tuyt i nn c 3 h vn cng tn ti Uv mu C1 C2 f(Hz) SMP FM m thanh EY 19. 2.4.1. Mi quan h gia EY;ER;EG;EB Trong tt c h mu tn hi chi lun c xc nh bng biu thc EY=0.3ER+0.59EG+0.11EB 20. 2.4.2. Ti sao c c biu thc EY=0.3ER+0.59EG+0.11EB Do cm gic v chi 100% ca mt c s tham gia ca 30% nh sng ; 59% nh sng l cy; 11% ca nh sng lam nhy ca vidicon cng c ch to sn ging y nh nhy ca mt ngi c tin tc ca nh mu khi to hnh en trng camera mu 3 thnh phn R;B;G c tch ring v vy mun c chi phi nhp chung chng theo t ln trn 21. 2.4.3. Kho st tn hiu chi EY Sc Thnh phn EY=0.3ER+0.59EG+0.11EB Lam(B) R=0,G=0 EY=0.30+0.590+0.111=11% (R) G=0,B=0 EY=0.31+0.590+0.110=30% L cy(G) R=0,B=0 EY=0.30+0.591+0.110=59% L(C) G+B; G=1;B=1 EY=0.30+0.591+0.111=70% Vng(Y) G+R; G=1; R=1 EY=0.31+0.591+0.110=89% Trng(W) R+B+G; R,G,B=1 EY=0.31+0.591+0.111=100% Tm(M) R+B; R=1;B=1 EY=0.31+0.590+0.111=41% 22. 2.5.1. S lin quan gia tn hiu mu vi t l pha trn c bn ER EY =ER - 0.3ER - 0.59EG - 0.11EB = 0.7ER - 0.59EG - 0.11EB EG EY = - 0.3ER + 0.41EG 0.11EB EB EY = - 0.3ER 0.59EG + 0.89EB 23. 2.5.2. in p chun ca 8 sc mu(EY=100%) ER(V) EG(V) EB(V) EY(V) ER-EY (V) EG-EY (V) EB-EY (V) Trng 1 1 1 1 1 0 0 Vng 1 1 0 0.886 0.114 0.114 - 0.861 L 0 1 1 0.701 - 0.701 0.299 0.299 Lc 0 1 0 0.587 - 0.587 0.413 - 0.587 Ta 1 0 1 0.413 0.587 - 0.413 0.587 1 0 0 0.299 0.701 - 0.299 - 0.299 Lam 0 0 1 0.114 -0.114 - 0.114 0.866 en 0 0 0 0 0 0 0 24. 2.5.3. in p chun ca 8 sc mu(EY=75%) ER(V) EG(V) EB(V) EY(V) ER-EY (V) EG-EY (V) EB-EY (V) Trng 1 1 1 1 0 0 0 Vng 0.75 0.75 0 0.664 0.086 0.086 - 0.684 L 0 0.75 0.75 0.526 - 0.526 0.024 0.224 Lc 0 0.75 0 0.440 - 0.440 0.310 0.440 Ta 0.75 0 0.75 0.310 0.440 -0.310 0.440 0.75 0 0 0.224 0.526 - 0.224 - 0.224 Lam 0 0 0.75 0.086 - 0.086 - 0.086 0.664 en 0 0 0 0 0 0 0 25. 2.5.4. Ti sao khng la chn EG-EY? - Vi cng sng chun EG-EY c qung bin thin b nht(thng tin khng r rng) - Di thng ca EG-EY ln hn 2 tn hiu cn li gy kh truyn ti hn - C th ly ra EG-EY t 2 tn hiu kia c c EG-EY bn thu EG-EY=-0.518(ER-EY)-0.186(EB-EY) 26. 2.5.5. Biu din mu theo ta mu sc? Y R M B C G -0.89 -0.59 -0.3 0.7 0.890.59 0.11 0.59 -0.11 -0.59 -0.7 ER-EY EB-EY W 0.3 </p>