Return-to-zero (RZ) line coding

Return-to-zero (RZ) describes a line code used in telecommunications signals in which the signal drops (returns) to zero between each pulse. This takes place even if a number of consecutive 0's or 1's occur in the signal. The signal is self-clocking.It suffers from using twice the bandwidth to achieve the same data-rate as compared to non-return-to-zero format.