3_RC_DISCRETIZAREA VOCII.pdf
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Transcript of 3_RC_DISCRETIZAREA VOCII.pdf
![Page 1: 3_RC_DISCRETIZAREA VOCII.pdf](https://reader034.fdocuments.net/reader034/viewer/2022051620/55cf9bb4550346d033a71274/html5/thumbnails/1.jpg)
Reprezentarea în domeniul timp a principiului esantionării
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Reprezentarea în domeniul frecvenţă a principiului eşantionării
f
s(t)
f
E(t)
f
sE(t)
fM
fE 2.fE
fM fE - fM fE +fM
![Page 3: 3_RC_DISCRETIZAREA VOCII.pdf](https://reader034.fdocuments.net/reader034/viewer/2022051620/55cf9bb4550346d033a71274/html5/thumbnails/3.jpg)
Transmisie cu eşantionare
EŞATIONARELinie (km)FTJ
4KHzFTJ
4KHzSREFĂCUT
RECEPŢIEEMISIE
SANALOG
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Semnale de eşantionare pentru multiplexarea în timp
E1
t
E2
t
E3
t
![Page 5: 3_RC_DISCRETIZAREA VOCII.pdf](https://reader034.fdocuments.net/reader034/viewer/2022051620/55cf9bb4550346d033a71274/html5/thumbnails/5.jpg)
Principiul transmiterii semnalelor multiplexate în timp
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Principiul discretizării semnalelor Tr
epte
de
cuan
tizar
e
1 2 3 4 5 6 7 8 9 10 11
10987654321
Sem
nalu
leşa
ntio
nat
şi c
uant
izat
Momente de eşantionare
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Caractristica de cuantizare uniformă Zgomotul de cuantizare
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Cuantizare uniformăZgomot de cuantizare
Niveluri de cuantizare
Ieşire numerică
Intrare analogică
Zgomot de cuantizare
1 / 2
-1 / 2
0.5 1.5 2.5 3.5 4.5
5
4
3
2
1
Niveluri de decizie
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Niveluri de cuantizare
Ieşire numerică
Intrare analogică
Zgomot de cuantizare
1 / 2
-1 / 2
1 2 3 4 5
1.5
0.5
Niveluri de decizie
2.5
3.5
4.5
Cuantizare uniformăZgomot de cuantizare
![Page 10: 3_RC_DISCRETIZAREA VOCII.pdf](https://reader034.fdocuments.net/reader034/viewer/2022051620/55cf9bb4550346d033a71274/html5/thumbnails/10.jpg)
Caracteristica de cuantizare neuniformăZgomotul de cuantizare
Ieşire numerică
Intrare analogică
Zgomot de cuantizare
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Principiul compresiei
Ieşire numerică
Intrare analogică
LINIAR
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CAN cu compresie
![Page 13: 3_RC_DISCRETIZAREA VOCII.pdf](https://reader034.fdocuments.net/reader034/viewer/2022051620/55cf9bb4550346d033a71274/html5/thumbnails/13.jpg)
Legea de compresie A
0 2-52-42-3 2-2 2-1 1
1/8
2/8
3/8
4/8
5/8
6/8
7/8
1
0 2-7 2-6 2-5
0
1
2
3
4
5
6
7
0
1
2
Intrare analogică
Ieşire numerică
1/8
2/8
3/8
0÷15
![Page 14: 3_RC_DISCRETIZAREA VOCII.pdf](https://reader034.fdocuments.net/reader034/viewer/2022051620/55cf9bb4550346d033a71274/html5/thumbnails/14.jpg)
Transmisia cu compandare
CANcompresie
CNAexpandare
Y
numeric
z=x
analog
x
analog
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Principiul transmisiei cu compandare
Ux
Y
COMPRESIE
EXPANDARE
UZ=UX
TRANSMISIE Y
Ux – analogic iniţialY – numeric comprimatUz – analogic refăcut
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Compresie + expandare analogice
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Compresie + expandare numerice
Y
8 biţi
z=xxCompresie
cu LUT
XEMISIE RECEPŢIE
CAN12 biţi
ZExpandare cu LUT
CNA12 biţi
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Compandare direct în CNA/CAN (CODEC)
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CNA cu expandare
>>16I0 η
>>8I0 v1
>>4I0 v2
>>2I0 v3
>>I0 v4
>>0.5I0
l1l2/l3 UCNA
UCNA
UCNA+
l1l2l3
l1/l2l3
l1/l2/l3
/l1l2l3
/l1l2/l3
/l1/l2
20
2-1
2-2
2-3
2-4
2-5
2-6
s
I
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Legea de compresie A
0 2-52-42-3 2-2 2-1 1
1/8
2/8
3/8
4/8
5/8
6/8
7/8
1
0 2-7 2-6 2-5
0
1
2
3
4
5
6
7
0
1
2
Intrare analogică
Ieşire numerică
1/8
2/8
3/8
0÷15
![Page 21: 3_RC_DISCRETIZAREA VOCII.pdf](https://reader034.fdocuments.net/reader034/viewer/2022051620/55cf9bb4550346d033a71274/html5/thumbnails/21.jpg)
CAN cu compresie
+-
+-
+-
+-
20
2-1
2-2
2-3
sUCNA
k1
k2
k3
k4
>>16I0
>>8I0
>>4I0
>>2I0
>>I0
η
v1
v2
v3
v4
UX
I
l1