![]() Since most military ships have multiple communications and radar transmitters, the levels and frequencies can be much higher than for commercial ships.Ī classic tale of military EMC at sea was the sinking of the HMS Sheffield in the Falkland Islands War in 1982. ![]() Susceptibility concerns are also severe, and include RF and power disturbances. Ships with metal hulls have vastly different EMC concerns depending on whether the equipment is located above deck (outside) or below deck (inside.)įor both the military and commercial environment, emissions concerns are severe and are aimed at protecting communications and navigation receivers, including radar. Marine Based – These environments include large surface ships, submarines, and even smaller water craft. Nevertheless, commercial vehicular electronics can be expected to do fairly well in military environments, but may need some additional protection for radar and EMP.ĭue to their experience working with harsh environments, we’ve found that commercial vehicular EMC engineers often have a relatively easy time making the transition to military electronics. Military vehicles share these same concerns, but as with fixed systems, the frequencies and amplitudes may be well above commercial levels. The susceptibility concerns are also severe, and include RF, ESD, and a range of power transients and other power disturbances unique to vehicles. With secondary concerns for protecting land mobile VHF/UHF radios. The emissions concerns are severe, and usually aimed at protecting entertainment radios (AM/FM), Even for commercial vehicular electronics, these can be quite harsh. Mobile Land Based – These environments include cars, trucks, buses, etc. The little bit of good news is that commercial levels for ESD and power disturbances are often still adequate. Commercial susceptibility requirements may also be inadequate, due to radio and radar transmitters with higher radiated field levels, and EMP. Also, many military systems are designed to include protection against EMP (electromagnetic pulse) effects from nuclear weapons, which adds another level of complexity.Īs such, commercial emissions requirements may not be adequate to protect nearby military communications receivers, which can be much more sensitive that a television receiver. ![]() Due to radar systems, those frequencies can extend to 40 GHz or more, well above the typical 1-5GHz upper limits for commercial equipment. Both field levels and frequency ranges can be much higher than commercial environments. These same buildings on a military base, however, may pose much more severe conditions, particularly for radiated emissions and susceptibility. The susceptibility concerns are a bit more challenging, and include threats such as RF (radio frequency) energy from nearby hand held radio transmitters, human ESD (electrostatic discharge), and power disturbances such as lightning or EFT (electrical fast transients.) The emissions concerns are moderate, and are aimed at protecting nearby television receivers. As an aside, this is the primary EMC environment for most commercial electronics. For commercial electronics, these are considered relatively benign in terms of EMC. Here are some examples of five general environments and their associated threats, and how they contrast with nonmilitary environments.įixed Land Based – This environment includes residential and office buildings. These threats are typically more severe than in commercial environments. This leads to subsets of requirements, and even tailoring in select cases.įurthermore, military systems are often subjected to multiple threats. Fortunately, most systems only need to operate in selected environments, rather than in every potential situation. ![]() These can range from the arctic to the desert, and from the bottom of the ocean to outer space. Unlike commercial equipment, military systems may need to work in a wide range of environments. Multiple Environments with Multiple Threats In this article, we’ll explore some of the unique EMC challenges presented by military electronics, and how they differ from those of the commercial world. It can also lead to frustration to those wishing to use COTS (commercial off the shelf) equipment in military environments. This can lead to frustration for those moving into military EMC from other areas. The threat levels, and the resulting requirements, are usually more stringent than found in the commercial world.Īs a result, commercial design techniques are often woefully inadequate for military applications. Multiple environments combined with multiple threats lead to multiple requirements. Military EMC design can be particularly vexing.
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