Digital communication device

#The present invention relates to a digital communication device. More particularly, this invention relates to a digital communication device such as an xDSL communication modem or an xDSL communication device, which, when receiving data, optimally corrects transmission path characteristics comprising noise transmitted from multiple half-duplex communication devices, transmitting via a half-duplex transmission path.

#Recently, an ADSL (Asymmetric Digital Subscriber Line) communication system, an HDSL (High-rate Digital Subscriber Line) communication system, an xDSL communication device system such as an SDSL, which perform high-speed digital transmission of several megabits/second using an existing copper cable for telephone, are attracting attention as cable digital communication systems. The xDSL communication system used in these is known as a DMT (Discrete MultiTone) variable demodulation system. This system is standardized in T1.413 of ANSI and elsewhere.

#In this digital communications system, when an xDSL transmission path and an ISDN transmission path of an ISDN communications system, which is a half-duplex communications system, are adjacent to each another when for instance they are converged together or the like in a midway collection guide, an xDSL transmission along the xDSL transmission path is affected by interference noise from other circuits such as the ISDN transmission path, leading to problems such as a loss of speed. Various countermeasures have been adopted.

#FIG. 1 shows the outline and the like of a digital communication system for which a digital communication device of the present invention is used;

#FIG. 2 shows a constitution of a receiver system of an ADSL remote terminal end transceiver unit (ATU-R) 14 according to a first embodiment of the digital communications device of the present invention;

#FIGS. 3(a) to (d) show the change and the like of the amount of error when carrying out coefficient training with a TEQ and an FEQ while switching between a NEXT noise and a FEXT noise according to the first embodiment;

#A first embodiment of a digital communication device of the present invention will be explained below referring to the drawings.

#In the following embodiment, a half-duplex communication device at the end applying interference noise is assumed to perform TCM-ISDN communication in which time-division half-duplex communication are transmitted along a half-duplex transmission path. As a result, the digital communication device at the end applying interference noise is assumed to perform ADSL communications, which is a type of xDSL communications system.

#FIG. 1 shows a summary of a digital communications system using a digital communications device of the present invention.