![]() The designer of military electronic equipment has an abundance of guidance available for successfully meeting the EMC demands of the intended operating environments. Prior revision levels A-E may still be specified for testing. The current version is MIL‑STD‑461F (2007), and updates to it are in the planning stage. In 1999 the 461D and 462D standards were merged into one document, MIL‑STD‑461E. Subsequent revisions were designated B, C, and D. ![]() After revision, MIL‑STD‑461A was issued in August 1968. That program resulted in 1967 in military standards 461 (requirements), 462 (methods) and 463 (definitions and acronyms). In 1966, EMC personnel of the three military departments jointly drafted standards addressing the overall EMC needs of the Department of Defense. In 1960 the US Department of Defense enacted a comprehensive electromagnetic compatibility program that charged the military services to build EMC into all of their communications and electronics equipment. ![]() The differences made it quite expensive for a test lab or manufacturer to be fully equipped to test to all EMC specifications. Unfortunately, over this period of time, the various military EMC standards diverged from each other in test frequency ranges, limits and required test equipment. These specifications also detailed the test configurations and methods for demonstrating compliance. ![]() These specifications limited the levels of conducted and radiated emissions, and they set susceptibility levels which systems and equipment must reject. In the period 1950 – 1965, each major military agency imposed its own EMC specifications. In 1942 it was superseded by specification 71-1303, “Vehicular Radio Noise Suppression.” With the increased use of mobile military radio communications, SCL-49 became inadequate. It required shielding of the vehicle ignition system, regulator and generator. It was published by the US Army Signal Corps in 1934 as SCL-49, “Electrical Shielding and Radio Power Supply in Vehicles”. The first US military specification on EMC also addressed this problem. Reception was degraded by ignition noise and electrostatic buildup caused by non-conductive rubber tires. Test methods generally differ from their commercial counterparts in both setup and detail.ĮMC problems in commercial applications were first noted worldwide in the 1930s when early broadcast radios were being installed in automobiles. The operational performance of an equipment or subsystem shall not be degraded, nor shall it malfunction, when all of the units or devices in the equipment or subsystem are operating together at their designed levels of efficiency or their design capability.Īs we shall see, this is the modest starting point for military EMC, which extends to both lower and higher frequencies than most commercial EMC standards and to both lower emission limits and much higher susceptibility requirements. This is a basic requirement in military EMC standards for example, in MIL‑STD‑461F clause 4.2.3: The starting point for EMC is self-compatibility, where the final product or system does not interfere with its own operation. These provide the design guidance, along with competent engineering practices, for a cost-effective and robust military product design.Įlectromagnetic compatibility (EMC) requires the component, equipment or system to perform its designed functions without causing or suffering unacceptable degradation due to electromagnetic interference to or from other equipment. The full cycle of US military product development from environmental assessment, to definition of requirements, to test reports, is carefully spelled out in the relevant military standards or ancillary documents for the applicable physical and electromagnetic environments. Defining the gap between the commercial equipment’s environmental performance and its military expectations is a first step in determining its potential suitability. But many types of commercial equipment are unlikely to meet all military environmental requirements as manufactured, so some modification or re-design is usually needed. In order to expedite equipment availability and reduce cost, the acquisition of commercial-off-the-shelf (COTS) equipment for US military applications is an attractive consideration. Severe shock, vibration, heat, humidity and airborne contaminants are common in land, sea and air platforms.Ĭoupled with dense packaging, high-power radio and radar illumination, Hazards of Electromagnetic Radiation to Ordnance (HERO), and a possible electromagnetic pulse (EMP), the military equipment environmental requirements can be extreme indeed. The reliable operation of complex electronic communications, control and armament systems in extreme environments demands stringent design criteria and careful validation.
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