T1 information is transmitted as positive and negative marks which alternate. If an error occurs in a 0, converting it to a 1, there will be two consecutive 1s of identical polarity, which violates the polarity rule. The CSU can transmit and receive. They can store and display facility performance parameters, including error seconds, failed seconds, and bit error rate. If properly designed, a CSU can provide conversion between D4 alternate mark inversion and ESF signals.
Regenerative repeaters create brand new pulses to send along the line.
The repeater examines each pulse and decides if it is a binary one or zero. Repeaters are normally placed about one mile apart. This allows them to reliably regenerate the 1,544,000 pulses per second. Network master clocking provides a common master reference to all nodes attached to its network. This method requires reliable network transmission because failure of the master node results in the loss of the entire network.