D2 channel bank: Physical design and introductory program

The D2 Channel Bank is designed to provide simplified engineering, installation, and maintenance. Integral voice-frequency alarm and access are provided in a packaged shop-wired frame with a centralized built-in test capability to facilitate initial line-up, testing, and trouble shooting. Circuits are implemented with discrete components and with thin-film and silicon-integrated circuits. Low cost, reliable assembly and wiring techniques are employed. The frame organization and circuit partitioning provide a functional arrangement of circuits with good electrical isolation between critical multiplexing and coding functions. An introductory program and an on-going reliability program have demonstrated the adequacy of both equipment and documentation. In the first 21 months of operation, approximately 3 percent of the circuit packs shipped have failed in initial line-up or in-service. This compares favorably with the performance of similar systems, and recent design modifications are expected to result in substantial improvements.