- ( ) ( ).
- - ( 300 3400 ) , - .
n ( , );
n ( , ).
n .
- N , f0, 3f0, 5f0, 7f0,..., f0 = N/2. - 1/3, 1/5, 1/7,... f0. , 0, 7f0. 971 , , 300 . .
- fc fc+fm fc-fm, fm - , . fm . ( 2fm), , 2fm. 3100 / 2 =1550 .
- , , . .
(Quadrate Amplitude Modulation) - 8 4 . 32 .
, , , .
, .
:
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- ( , , );
- ( , , , , , );
- ;
- .
. NRZ (Non Retrurn to Zero). .
, , . , , . , . , . f0 = N /2.
. (Bipolar Alternate Mark Inversion, AMI), NRZ.
, , , . . , NRZ, , N/2. AMI , NRZ, , . , f0 N/4. , 3 , .
. (Non Return to Zero with ones Inverted, NRZI) , AMI, . , . , ( ).
AMI, NRZI . . , , .
, - . , .
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. , . .
, . , .
. , Ethernet, Token Ring.
. , . , . , . . , , , N, - N/2.
21Q. , . 00 - -2,5 , 01 - -0,833 , 11 - +0,833 , 10 - +2,5 . . , NRZ, , , AMI, NRZI, .
AMI, NRZI, 2B1Q, , , . .
, , , , .
4/5 4 5 . 16 32. 16, , (code violation). , . , .
, . , . , 8/6.
( 100 / 125 ). , , .
.
. ,
Bi = Ai xor Bi-3 xor Bi-5,
Bi , i- , Ai , i- , Bi-3 Bi-5 , .
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110110000001 110001101111, .
,
i = i xor Bi-3 xor Bi-5,
.
, .
Bipolar AMI :
B8ZS (Bipolar with 8-Zeros Substitution) , 8 .
V-1*-0-V-1*, V , , , , 1* - , , , . 8 2 , - . 8 . .
HDB3 . , V. V . , . , 000V, 1*00V.
, .