What is multilevel binary?
These codes use more than two signal levels. There are two coding schemes: Bipolar-AMI and Pseudoternary.
Which line encoding technique has twice its bandwidth?
The Manchester NRZ line code has the advantage of always having a 0 DC value, regardless of the data sequence, but it has twice the bandwidth of the unipolar NRZ or polar NRZ code because the pulses are half the width.