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ModulatorModulator

nn

cuadraturcuadratur

(I)(I)

Sistemul PAL utilizeaz semnale diferende culoare comprimate:

EU = kB EB-Y = 0,494

EB-Y

EV = kR ER-Y = 0,877 ER-Y

MAPS

MAPS

Oscilator

EV

EU

EVcosSPt

cosSPt

sinSPt

EUsinSPt

EC

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ModulatorModulator

nn

cuadraturcuadratur

(II)(II)

EC = EVcosSPt + EUsinSPt

= |EC|sin(SPt + C)

EU

|EC|

EV

C

2V

2UC EEE +=

U

VC

E

Etg =

saturaia culorii nuana culorii

alb

albastrunegru

verderou

LUMINAN

SATURAIE

NUAN

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PrincipiulPrincipiul

PALPAL (Phase Alternation Line)(Phase Alternation Line)

U

ECV

C U

ECV

C UEC

V

C

EC(n,)

U

ECV

C+

EC(n,)

EC

U

V

C U

EC

*

V

-C U

EC

*

V

-C

EC*(n+1,)

U

V

C-

EC**(n+1,)

linie n

linie n+1

iniial emisie canal cu eroare

de faz

recepie

C+

EC(n,)

U

V

C-

EC**(n+1,)

~2EC

ntrziere

TH

ECEC

n+1

n

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ModelulModelul color standard:color standard: saturasaturaieie 75%75%

(I)(I)

n sistemul PAL se limiteaz saturaia

maxim a culorii la 75%

amplitudinea vrf la vrf a semnalului EC(EY+|EC|,EY-|EC|) este limitat la:

1 = nivelul de alb

- 0,25 = jumtate din amplitudinea impulsului

de sincronizare

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ModelulModelul color standard:color standard: saturasaturaieie 75%75%

(II)(II)

Exemplu: Saturaie 100 %

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ModelulModelul color standard:color standard: saturasaturaieie 75%75%

(II(IIII))

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ModelulModelul color standard:color standard: saturasaturaieie 75%75%

((VIVI))

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LiniaLinia TV PALTV PAL

0,7V

0,3V

1VVV

UVF

EY

SC

SH

EY+EC

EY-EC

1

1,001,000,88

0,75

0,690,43

0,320,06 0

-0,13

-0,25-0,25

00,090,22

0,310,44

0,530,66

EY nivelul de griEC QAM peste nivelul de griSC burst fSC

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SpectrulSpectrul PAL (PAL (ntrentreesereesere 3/4)3/4)

Y

EU

EV

CEU+EV EU+EV EU+EV

EU+EVEU+EVY Y YEV EV EV

(k-1)fH kfH (k+1)fH

(k-1)fH kfH (k+1)fH

fSC4,43MHz

fH/2fH/2

fH3/4fH

283fH

discretkfH

identickfH

PAL: TV=2TH kfH/2

identickfH/2

fSC=(283+3/4)fH

ntreesere

3/4

f

f

f

f

f

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CodorulCodorul PALPAL

matrice

de codare

R

G

B

ntrziere

V

U

MODV

MODU

1

2

180

90

OSCfSC

(8/1135) timer

impuls

cos SPt

sin SPt

K

St S

SVCC

P

EC

EYEY

EV

EU

2fH

FTJ

FTJ

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DecodorulDecodorul PALPAL

ER

EG

EB

ntrziere

DEMOD

matrice

180

90burst

4,43 MHz

2EVcos SCt

sin SCt

SVCCPAL

EYEY

EV

EUDEMODsepararecomponente

2EUsin SCt

cos SCt

FTB

4,43EC

90

270

Rejecie

FTJ

FTJ

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SeparareaSepararea componentelorcomponentelordede culoareculoare

(I)(I)

2*+1,3+2*,...

2*-1,3-2*,...

demodulatoarentrziereTH= 64s

1

2

amplificatorcu ieire nantifaz

1

1

2*

1

2*

3

2*

3

4*

3

4*

EC:1,2*,3,4*,...

-+

EC= EVcos SPt + EUsin SPt

EC*= -EVcos SCt + EUsin SCt

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SeparareaSepararea componentelorcomponentelordede culoareculoare

(II)(II)

1 EC+EC* =

= EVcosSCt + EUsinSCt - EVcosSCt + EUsinSCt =2EUsin SCt

2 EC*-EC == -EVcosSCt + EUsinSCt - EVcosSCt - EUsinSCt

= -2EVcos SCt

EC-EC* =

= EVcosSCt + EUsinSCt + EVcosSCt - EUsinSCt

= 2EVcos SCt