With every passing year the amount and complexity of electronic equipment aboard modern navy vessels increases. It is important that this equipment, including systems such as communications, radar, navigation, weapons control and electronic warfare, don't interact with each other or the environment in ways that cause equipment failures, damage or radiation hazards to personnel, ordnance or fuel. Similarly, navy vessels have an ever increasing need to maximize their survivability by ensuring that their signatures, both radar cross section (RCS) and infrared (IR), are as small as possible.
It is preferable that these issues are identified during development as it is much cheaper and quicker to make changes during the design phase than after the ship is constructed. This is also the case when new equipment is added or a ship receives some modifications or undergoes a refit.
Throughout its life a naval vessel will undergo many changes and supposedly similar vessels will actually end up with quite different electromagnetic configurations and signatures. Keeping track of all these changes and understanding the resulting differences in performance and capabilities is a complex task. The probabilities of success and survival of any mission are increased by being able to identify the ship or ships which provide the closest match to the specific mission requirements.