本技术报告描述了一种线路中断检测功能，用于检测位于网络中的设备和客户安装（CI）之间的接入线路中断。该方法基于通过使用以20波特调制的BPSK（二进制相移键控）的40 Hz载波来维持CI和第一网络元件之间的同步。为了最大限度地提高安全性，载波采用255个伪随机序列中的一个进行数字编码。在安装时，第一个网元经过训练，只识别其中一个伪随机序列。

This Technical Report describes a Line Break Detection functionality to detect a break in an access line between equipment located in the network and the customer installation (CI). The methodology is based on maintaining synchronization between the CI and the first network element by using a 40 Hz carrier that is BPSK (binary phase-shift keying) modulated at 20 baud. For maximum security, the carrier is digitally encoded with one of 255 pseudo-random sequences. At the time of installation, the first network element is trained to recognize only one of these pseudo-random sequences.