ADSL MODEM AND ITS COMMUNICATION METHOD

摘要

PURPOSE: To reduce the interference of an upstream signal with a downstream signal due to the skirt phenomenon, thereby enabling the long distant ADSL communication. CONSTITUTION: A center side transmits downstream signals using a designated carrier predetermined by communication standards when a hand shake procedure starts. If no line can be connected with a party's ADSL modem in the signal transmission using the designated carrier, it transmits downstream signals again using an alternate carrier shifted to the high frequency side about the designated carrier adjacent to a carrier used for the upstream. A remote side detects signals with the designated carrier predetermined by communication standards from the downstream when a hand shake procedure starts. If the signal with the designated carrier cannot be normally received within a specified time after starting the shake hand procedure, it detects signals with the alternate carrier after the carrier change in coincidence with the carrier change at the transmit side.