Types of Errors on a T1 link include the following:
• Bipolar Violation (BPV): Two consecutive pulses are received with the same polarity.
• Loss of Signal (LOS): No signal transitions on a T1 link within a certain time window.
• Loss of Frame (LOF): T1 frame out of synchronization. With or without LOS.
• Excessive Zeros (EXZ): Eight (8) consecutive zeros appear on the link.
• “1”s Density Violations: Violation to the “Ones Density Rule” which states that in every 24 bits of information to be transmitted, there must be at least three pulses and no more than 15 zeros may be transmitted consecutively. Similar to EXZ error.
• Incorrect Pulse Widths: The pulse widths at the output of the customer network channel terminating equipment are out of specifications.
• Incorrect Signal Levels: The pulse amplitudes at the output of the customer network channel terminating equipment are out of specifications.
Incorrect pulse width or incorrect pulse amplitude or both will cause the pulse template mask to be violated.