THE HDSL ENVIRONMENT

This paper presents a tutorial on the physical environment in which high bit-rate digital subscriber line (HDSL) transceivers will have to evolve and succeed. Special attention is given to the most damaging impairments that are encountered in subscriber lines, such as propagation loss, linear distortion, crosstalk, bridged taps, and impulse noise. Somewhat less important impairments, such as change of gauge, temperature variation, and thermal noise, are also briefly described. Finally, the paper concludes with a discussion of the capacity of a twisted-pair channel in a crosstalk-dominated environment.