The most common signal formats are as follows:
- Non-Return-to-Zero (NRZ)
- Delayed Non-Return-to-Zero (DNRZ)
- Return-to-Zero (RZ)
- Return-to-One (R1)
For NRZ the waveform switches to a “1” and stays at that value until the next cycle boundary, when a valid bit occurs in the cycle. For DNRZ Similar to NRZ, the waveform switches to a “1” after a specified delay time, when a valid bit occurs in the cycle. For RZ the waveform switches to a “1,” then back to a “0” within the same cycle, when a valid bit occurs in the cycle. R1 assumes the cycle begins with a “1”, then switches to a “0” when the
bit is valid, then switches back to a “1” before the cycle ends.
