Encode 10010110001 with NRZ-L, NRZ-I, diff. Manchester

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

Polar NRZ-L

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

Polar NRZ-I

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

Differential Manchester

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

Rules used

• NRZ-L: level = bit value (1 = +V, 0 = -V).
• NRZ-I: the level changes at the start of every 1; it stays the same for a 0.
• Differential Manchester: there is always a transition in the middle of the bit (clock); a 0 has an extra transition at the start of the bit and a 1 has none.