– Self–Synchronisation: There is enough timing in-
formation built into the code so that bit synchronisers
can extract the timing or clock signal. A long series of binary 1’s or 0’s should not cause a problem in time
recovery
– Low Probability of Bit Error: Receivers can be
designed that will recover the binary data with a low
probability of bit error when the input data is corrupted
by noise or ISI
– A Spectrum that is Suitable for the Channel:
For example, if the channel is AC coupled, the PSD of
the line code signal should be negligible at frequencies
near 0. In addition, the signal bandwidth needs to be
sufficiently small compared to the channel bandwidth,so that ISI will not be a problem
– Transmission Bandwidth: This should be as small
as possible
– Error Detection Capability: It should be possible
to implement this feature easily by the addition of
channel encoders and decoders, or the feature should
be incorporated into the line code
February