Performance of 2B1Q transmission system for ISDN basic access

Based on extensive studies by the ANSI T1 Committee, the 2B1Q line code was chosen as the carriage mechanism for ISDN basic rate deployment. To explore the performance limits of this code, a system was built and tested. The system is described, and issues and performance measurement techniques are addressed. It is demonstrated from analysis of the measurement results, the loop loss distribution, and the worst-case crosstalk values that up to 98% of the North American nonloaded loops can be covered with adequate performance and noise margin