Digital multiplexed spacecraft communications and data handling subsystem

The NASA Standard Communication and Data Handling subsystem (C & DH) is the Multimission Module that provides a full telemetry and command link between the host spacecraft and the ground facility. The Module consists of standard components that perform the functions of communications with spacecraft subsystems, scientific instruments, sensors, and an onboard computer. A detailed description of the C & DH system is presented. This system demonstrated the viability of a microprocessor as the major control element in a spacecraft control and data handling system. It provides a method of replacing hardware elements without sacrificing performance and at the same time provides a highly programmable and versatile system capable of executing complex tasks.