The rule-based approach, i.e. following electromagnetic interference standards, is the basic methodology assumed to result in electromagnetic compatible systems operating properly in their intended environment. For complex systems we need a smarter approach, based on assessing and controlling the electromagnetic risks. This risk-based approach is described, and applied to naval ships.

Software engineering borrowed modularity from hardware engineering. However, at that time their primary reason -module independence allowing abstraction and hierarchy -was less obvious to the hardware engineer. As hardware becomes more complex and faster, electromagnetic independence is at stake. The current boundary is a concept that allows the electromagnetic separation of modules at any level in the hardware platform within a system. Hence, it is a powerful tool to boost system reliability and maintainability.

Above deck, cables on naval ships are exposed to highintensity radiated fields and nuclear electromagnetic pulse (NEMP) that may cause conducted interference and generate electromagnetic fields that exceed the immunity levels of commercially available equipment above and below deck. Exposed cables, such as open power plugs or lighting cables, are modeled and characterized both as a monopole antenna perpendicular to the deck and as a transmission line, representing a cable close to the deck. The placement of an illuminated cable close to the deck is a good protection measure for long cables at low frequencies, which includes NEMP protection. The coupled pulse from a high-intensity NEMP illumination is not expected to cause damage on electric installations. It is shown that for exposed cable length of maximum 25 cm and not placed in the line of sight of transmitters above 400 MHz, no additional protection measures are needed.

IEC 60533 is a product standard that puts strict requirements on all equipment on board of ships. Except for dedicated bridge equipment, there are hardly any products available that comply. One aspect from this standard is the low emission limit for radio frequency protection of the maritime very high frequency radio telephony system. This limit appears not to be based on a minimum range to receive a distress call, but on the possibility of receiving the lowest possible signal in an assumed placement of equipment. An analysis of the standard and a reconstruction of their rationale have led to an alternative, functional requirement with proper rationale, which can give the system integrator more flexibility in choosing equipment. This novel risk-based approach results in the same objective, i.e., an interference-free environment. Measurements have been performed to demonstrate possible disturbance sources and to investigate the communication range.