Digital subscriber line communicating system

摘要

A digital subscriber line communicating system for communicating between a transmitting side and a receiving side through a communication line, comprising a hyperframe counter for periodically counting a predetermined number of continuous transmitting data symbols constituting a hyperframe synchronized with a timing signal, and a decoder for discriminating, based on the count value of the hyperframe counter, whether a transmitting data symbol belongs to a FEXTR or a NEXTR. A sequencer is provided for initializing the status during an initialization period before starting usual communication. The initialization period includes an activation and acknowledgement sequence, a transceiver training sequence, a channel analysis sequence, and an exchange sequence. According to a single bitmap mode, the initialization is carried out by transmitting modulated symbols through only inside of said sliding window. According to a dual bitmap mode, the initialization except for an S/N measuring sequence in the channel analysis sequence is carried out by transmitting modulated symbols through only inside of said sliding window, and the S/N measuring sequence is carried out by transmitting modulated symbols through both inside and outside of said sliding window.