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Waveforms for 1111000111

Short answer

NRZ-I: toggle at start of each 1, keep level for 0 (initial low). AMI: 0=0V; 1s alternate +V and -V starting +V. RZ: polar, return to zero mid-bit; 1 is +V half, 0 is -V half. Manchester: 1 low-to-high mid-bit, 0 high-to-low.

For a binary data sequence 1111000111 sketch (a) NRZ-I waveform, (b) AMI waveform, (c) RZ waveform and (d) Manchester waveform.

Bit stream: 1 1 1 1 0 0 0 1 1 1

Conventions used (state these in the exam, as books differ): level before the first bit is low (-V); NRZ-L/RZ: 1 = +V, 0 = -V (unipolar: 0 = 0 V); NRZ-I: a 1 toggles the level at the start of the bit, a 0 keeps it; RZ: the pulse returns to zero in the middle of the bit; Manchester: 1 = low-to-high and 0 = high-to-low transition at mid-bit; differential Manchester: always a mid-bit transition, an extra transition at the start of the bit for a 0 and none for a 1; AMI: 0 = 0 V, 1s alternate +V and -V starting with +V.

NRZ-I

      1   1   1   1   0   0   0   1   1   1  
+V   ----|   |---|               |---|   |---
 0       |   |   |               |   |   |   
-V       |---|   |---------------|   |---|

AMI

      1   1   1   1   0   0   0   1   1   1  
+V   ----|   |---|               |---|   |---
 0       |   |   |   |-----------|   |   |   
-V       |---|   |---|               |---|

RZ

      1   1   1   1   0   0   0   1   1   1  
+V   --| |-| |-| |-|             |-| |-| |-| 
 0     |-| |-| |-| |-| |-| |-| |-| |-| |-| |-
-V                   |-| |-| |-|

Manchester

      1   1   1   1   0   0   0   1   1   1  
+V     |-| |-| |-| |---| |-| |-|   |-| |-| |-
 0     | | | | | | |   | | | | |   | | | | | 
-V   --| |-| |-| |-|   |-| |-| |---| |-| |-|

AMI pulses: + - + - 0 0 0 + - + (the 1s alternate: + - + - then, after the zeros, + - +).

✓ Answer checked by Claude Sonnet 5.5

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