In AMI coding, how are bits represented?

0 as 0; 1s alternate between +V and -V

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2075 Asoj (CS II) · 6 marks

Line coding 10110101 (polar NRZ, unipolar RZ, AMI, Manchester)

Short answer

For 10110101, Polar NRZ: +V,-V,+V,+V,-V,+V,-V,+V. Unipolar RZ: +V,0 for first half for 1s, else 0. AMI: +V,0,-V,+V,0,-V,0,+V. Manchester: +V,-V,-V,+V,+V,-V,+V,-V,-V,+V,+V,-V.

Represent binary sequence 10110101 in Polar NRZ, unipolar RZ, AMI and Manchester codes.

Conventions (bit period $T_b$ , amplitude $V$ ):

Polar NRZ: 1 → $+V$ , 0 → $-V$ for the whole bit.
Unipolar RZ: 1 → $+V$ for the first half bit then 0; 0 → 0.
AMI: 0 → 0; 1s alternate $+V$ , $-V$ (first 1 positive, full-width pulses; an RZ version with half-width pulses is also used).
Manchester: 1 → $+V$ then $-V$ ; 0 → $-V$ then $+V$ (transition at the middle of every bit).

Bit sequence: 1 0 1 1 0 1 0 1

bits  1   0   1   1   0   1   0   1  

Polar NRZ:
+V  |‾‾‾‾    ‾‾‾‾‾‾‾‾    ‾‾‾‾    ‾‾‾‾
 0  |
-V  |    ____        ____    ____

Unipolar RZ:
+V  |‾‾      ‾‾  ‾‾      ‾‾      ‾‾
 0  |  ------  --  ------  ------  --

AMI (bipolar NRZ):
+V  |‾‾‾‾        ‾‾‾‾            ‾‾‾‾
 0  |    ----        ----    ----
-V  |        ____        ____

Manchester:
+V  |‾‾    ‾‾‾‾  ‾‾    ‾‾‾‾    ‾‾‾‾
 0  |
-V  |  ____    __  ____    ____    __

Levels in each bit (a pair means first half, second half):

Code	1	0	1	1	0	1	0	1
Polar NRZ	+V	−V	+V	+V	−V	+V	−V	+V
Unipolar RZ	+V,0	0	+V,0	+V,0	0	+V,0	0	+V,0
AMI (bipolar NRZ)	+V	0	−V	+V	0	−V	0	+V
Manchester	+V,−V	−V,+V	+V,−V	+V,−V	−V,+V	+V,−V	−V,+V	+V,−V

Code	DC component	Clock content	Bandwidth (first null)
Polar NRZ	Yes (if 1s and 0s unequal)	Poor in long runs	$R_b$
Unipolar RZ	Yes	Good for 1s, none for 0s	$2R_b$
AMI	None	Poor for runs of 0s	$R_b$
Manchester	None	Excellent	$2R_b$

✓ Answer checked by Claude Opus 5.5 (high effort)

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