The DRUH is a positioning and orienting sub-system for use on weapon and target systems. Electronic odometer (VMS) signals and GPS position and time data may optionally aid it. The DRUH may be used in a variety of host system configurations. Figure 5 shows the DRUH integrated with a host computer, VMS and GPS receiver. Figure 6 shows a configuration using a Control and Display Unit (CDU) operator interface and no VMS or GPS aiding.

The DRUH covered by this specification is military unique. It is mounted to the gun trunnion of the M109A6 Self-Propelled Howitzer and must operate through the extreme levels of gunfire shock. it also must operate after exposure to the nuclear, biological and chemical warfare environments and subsequent decontamination. Commercial inertial navigation systems are not designed to withstand such extreme environmental conditions and would experience catastrophic failure. The DRUH is used by multiple host systems and has extensive electronic data interchange requirements. There is no commercial specification or standard covering the command and message formats.