D4 Digital Channel Bank Family: Digital terminal physical design

This article describes the physical design of the D4 and related SLC™-96 subscriber loop carrier system digital terminals. A detailed description of the bay, channel bank, and plug-in designs is also included, along with other very important considerations such as thermal design, manufacturability, and the effective use of hybrid integrated circuit technology. The D4 was designed as a system that was significantly smaller, used less power, and had a lower cost than previous digital terminals. These objectives were realized by using the latest technology and the optimal physical design format. Since these are relatively high-production terminals, the basic design has been aggressively reduced in cost and has proliferated with expanding D4 and SLC-96 subscriber loop carrier terminal capabilities, lightguide applications, and the use of the D4 hardware in other systems.