Low-investment EMI pre-compliance for COTS technology insertion into submarine combat systems

A modern submarine’s combat system is largely dependent on commercial off the shelf (COTS) computer technology as a means of cheaply adopting the latest, high-performance, commercially developed and qualified systems to maintain capability. COTS technology is not normally designed for military use, nor is it necessarily compliant to military standards for electromagnetic interference (EMI), such as MIL-STD-461G. A gap analysis, based on a comparison of commercial and military EMI standards, showed that there is no guarantee of COTS EMI compliance to this military standard. Formal compliance testing at a certified test house is almost prohibitively expensive for purposes of early experimentation and component evaluation. This is due to the highly controlled, calibrated and specialist nature of such facilities. Because of this, they are normally only used for final compliance testing prior to acceptance of new designs into service. In order to reduce the risk of a compliance failure, pre-compliance testing should take place prior to and even during system design. Evidently, a need exists for a low-investment and practical test protocol to verify the EMI performance of such COTS equipment against the applicable military EMI standards. Background research was undertaken into the historical development of current commercial and military EMI standards, the trend and motivation for the use of COTS in the defence environment, as well as the mechanisms and theory of EMI design as applied to the submarine. This research was critical in the development of a gap analysis procedure as well as the development of low-cost and practical alternatives to formal EMI testing with simplified tests as pre-compliance test protocols