, Y 0, q' Y 1, q' , Y 2, q' Y 3, q' . , . . , . Y 0, q' Y 1, q' . , , . , 16-QAM Y 2, q' Y 3, q' .
-2 |
-2 |
Im (Ż) Y 1, q ¢ Y 3, q ¢ |
) 16-QAM a=2 |
Re (Ż) Y 0, q ¢ Y 2, q ¢ |
-4 |
-4 |
-4 |
-4 |
Im (Ż) Y 1, q ¢ Y 3, q ¢ |
) 16-QAM a=4 |
Re (Ż) Y 0, q ¢ Y 2, q ¢ |
-6 |
-6 |
-2 |
-2 |
.2.4. 16-QAM: a=2; a=4
2.3. OFDM
OFDM .
DVB-T , . , , - , , , . OFDM. , .
. (QPSK QAM) () , Re{ Ċ }= CI, , Im{ Ċ }= CQ. . , CI, CQ, .
. , , . , ( , ) . , , , , .
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|
( , ), k fk, Ck, Ck , fk:
Sk (t)=Re{ Ck exp(j 2 pfkt)}=Re{ Ck exp(j 2p kt / TU)}. ( 2.1 )
fk k - 1/ TU, , . OFDM, , , :
S (t)=S Sk (t) = SRe{ Ck exp(j 2p kt / TU)}, ( 2.2)
k k min k max.
, . , t nT ( T , n ):
S (nT)= Sn = Re{S Ck exp(j 2p knT / TU)}. (2.3)
(2.3) :
Xn = S Xk exp(j 2p kn / N). (2. 4 )
, Xn nT Xk ( N ( ), , k 0 (N 1). , , .
, (2.3) (2.4) , OFDM . , OFDM , N = TU / T OFDM 0 (N 1), . , (, ).
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OFDM ? , , . , , OFDM . OFDM (, ), OFDM . , . , ( ), . OFDM, , DVB-T, OFDM.
TU / N = T ( N ), (2.3), DVB-T. 1/ T . , T. DVB-T, 8 , 1/ T =64/7 . - .
DVB-T 8 , . . 7 8 . ( ), 7/8 . 6 (13,5´8192)/(858´19) .
, , . ( SQ (t), SI (t) S (t)):
SCk exp(j 2p fkt)= SI (t)+ jSQ (t).
F 0 ( ), ( 90). OFDM, F 0. , :
S 0(t)= SI (t)cos(2p F 0 t) SQ (t)sin(2p F 0 t)=
S{ CIk (t)cos[2p(fk + F 0) t ] cQk (t)sin[2p(fk + F 0) t ]}
OFDM (.2.5).
F 0 |
90 |
∑ |
S 0 |
SQ |
SI |
CK |
.2.5. OFDM
2.4. OFDM
OFDM (.2.6). , , OFDM , , , .
|
|
f |
60 |
40 |
20 |
8 |
4 |
, |
8 k |
2 k |
f fc |
1/ TU |
.2.6. OFDM
( TU /4, fc )
, OFDM (7,608258 2 k 7,611607 8 k) . .
2.5.
, . , , , , , , , , . ( ), . .
. , , , , (.2.7). , , . . , , ( - 0 ). , .
-, , OFDM. , . COFDM , . , , , . OFDM , .
2.6. DVB-T
, DVB-T, .2.1 (, , ). , , 1512 2k 6048 8k. "" . , , , RS, 6,75 (RS=1512/224 = 6048/896 = 6,75 = 6,75 /).
|
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OFDM |
.2.7.
c OFDM
2.1. DVB-T
8k | 2k | |
Tu, | ||
Tg, | 224, 112, 56, 28 | 56, 28, 14, 7 |
, | ||
, | 7,61 | 7,61 |
QPSK, 16-QAM, 64-QAM | QPSK, 16-QAM, 64-QAM | |
1/2, 2/3, 3/4, 5/6, 7/8 | 1/2, 2/3, 3/4, 5/6, 7/8 |
3. | DVB- |
3.1. DVB-T
3.2.
3.3.
3.4.
3.5.
3.1. DVB-T
. 3.1 DVB-T.
:
- MPEG-2 DVB CODICO -1000 - 2 .;
- MPEG-2 DVB CODICO RTM-3800;
- CODICO N-4000.
, :
- - ;
- - 2 .
( ) .3.2.
MPEG-2 DVB .
. MPEG-2
MPEG-2
.3.1. DVB-T
, , ASI-DVB . . COFDM .
G-2 EN 301.192 Internet - Internet .
IP MPEG-2 DVB , , -, IP-DVB . 48- () . , , . , :
- ( 30...40/, , MMDS, DVB-T);
- ( PID);
- ;
- ;
- ;
- .
MUX 1 RTM-3600 |
ASI |
1 E-1X00 |
V |
A |
A |
ASI 1 |
2 E-1X00 |
V |
A |
A |
ASI 2 |
IP-DVB IGW-600 |
ASI 3 |
ASI 4 |
ASI 5 |
ASI 6 |
ASI 7 |
ASI 8 |
Internet |
Internet |
Internet |
DVB-T |
SetTopBox |
.3.2. ( )
Fast Ethernet 100BaseT. DVB-ASI, , .
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MPEG-2 DVB MPEG-2/DVB, . , , , .
IGW-600 SCOPUS Network Technologies.
- IP- DVB . IGW-600 10/100BaseT , ( , , Internet), , , . IGW-600 DVB-ASI DVB ( SCPC) ( MCPC).
IGW-600 DVB EN 301 192 :
- IP-multicast ;
- , ;
- ;
- TCP/IP DVB ;
- 8192 PID ;
- 10000 ;
- ;
- .
CCU (Central Configuration Unit) , Windows NT. , , - , - . CCU IGW-600 , .
Internet , . , . USB .
3.2.
DVB-T :
DVB ( , , , , , ..);
( SFN MFN , , , CR Δ, , ..);