Choosing Military Or COTS Components?

Sept. 16, 2011
Designers of defense electronic systems must seek out commercial-off-the-shelf (COTS) components when practicalnot only to save money and avoid obsolescence, but also to integrate the latest technologies available.

ECONOMIC CONDITIONS can assert influence over electronic design strategies. At one time, the US government steered clear of commercial components or software in electronic defense systems. But with trying economic times comes a willingness to use commercial-off-the-shelf (COTS) components and software in military systems.

COTS components are considered an alternative to "one-off" components or subsystems that have been custom designed and built for specific military needs, typified by nonrecurring-engineering (NRE) costs that would drive up the cost of such a custom component. Some of these custom components, such as detector-log-video-amplifiers (DLVAs) and phase shifters built to a specific package requirement, have been built by mid-sized to smaller electronic component manufacturers, and the fear on the part of the military has always been to lose a source of a component that might not be easily duplicated elsewhere. Thus, there was the push to use hardware and software that might essentially be the same as versions sold to the general public.

A document released by the US Department of Defense (DoD) in 2000, "Commercial Item Acquisition: Considerations and Lessons Learned," spelled out the reasoning behind adopting commercial technology for defense-related systems (DoD Directive 5000.1): "Expanding the use of commercial items in DoD systems offers the DoD opportunities for reduced cycle time, faster insertion of new technology, lower life cycle costs, greater reliability and availability, and support from a more robust industrial base." Traditionally, commercial markets for electronic components have been orders of magnitude larger than military markets for similar components. A concern long faced by military system designers and integrators is that specialized, largely custom electronic components may not be available if the supplier of those parts is not diversified enoughi.e., also competing in commercial marketsto weather difficult economic times.

Similarly, that same year the US Air Force published "Ensuring Successful Implementations of Commercial Items in Air Force Systems" (available for download), which compared commercial and COTS items as defined by Federal Acquisition Regulation (FAR) and how COTS components could be put to optimum use in US Air Force Systems. It also differentiated commercial and COTS components, with a commercial item defined as one that may require modifications for use by the military, and a COTS item defined as one that can be sold for use without internal modifications.

For all its apparent benefits, the use of COTS components in military systems does have a downside. For one thing, when using COTS parts, there is the need to meet commercial regulatory requirements, such as for compliance or compatibility with the Restriction of Hazardous Substances (RoHS) directive to eliminate hazardous substances from electronic products and electronic-product manufacturing. This may require the use of halogen-free printed-circuit boards (PCBs), for example, or circuit materials capable of withstanding the higher temperatures used for lead-free solders. In addition, the short product cycles of commercial end products can limit the practical availability of COTS parts, since the larger commercial markets will dictate the need for those component parts more than smaller, specialized military markets. In some cases, government programs relied on commercial or COTS parts based on a strong commercial market. When the commercial markets faded, and the COTS components were considered obsolete, custom replacements were needed for the COTS parts.

Military standard (MIL-STD) documents can serve as guidelines for system integrators considering COTS components for a platform. Whether military-grade or COTS, a component must nonetheless comply with the conditions of screening and testing detailed in such documents as MIL-STD-883 for a wide range of environmental and mechanical conditions. Many tests have been designed to emulate the extreme conditions that an electronic system might face on land, sea, and in the air, no matter if the system contains military-grade or COTS components.

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