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MIL-STD-464B – A Review of the Latest Revisions to the Standard: Part 1

LATE-BREAKING NEWS UPDATE!

Due to problems in the digital publishing process, MIL-STD-464B 01 October 2010 is scrapped and MIL-STD-464C, release date 01 December 2010 will take its place. There are no technical changes from what are described in this three part article, but the replacement for MIL-STD-464A will be MIL-STD-464C. MIL-STD-464B dated 01 October 2010 will cease to exist.

As you read this article, MIL‑STD‑464B, “Electromagnetic Environmental Effects Requirements for Systems” is newly minted with an official release date likely to be 01 November 2010.

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VSWR and its Effects on Power Amplifiers

Voltage Standing Wave Ratio results from an impedance mismatch between a source (an amplifier) and a load (test application). This mismatch can influence the performance of the source.

MIL‑STD‑464 is the DoD top‑level E3 requirement set for procurement of complete or modified systems. “Systems” meaning an integrated platform of one type or another, such as a ground or air vehicle, a ship or submarine, a spacecraft or launch vehicle. Note that some systems can be parts of other systems, such as an F‑18 fighter aircraft that operates from an aircraft carrier.

MIL‑STD‑464B is the latest in a long line of standards that goes back to at least MIL‑I‑6051, “Interference Limits and Methods of Measurement; Aircraft Radio and Electronic Installations,” released in 1950. The ‑6051 series culminated in MIL‑E‑6051D, “Electromagnetic Compatibility Requirements, Systems,” released in 1967 and used until MIL‑STD‑464 replaced it in 1997.

The A & B revisions of MIL‑STD‑464 amend the original release but are evolutionary, not revolutionary changes. MIL‑STD‑464B has many changes, so many that the new Section 6.8, “Changes from Previous Issue” states, “Marginal notations are not used in the revision to identify changes with respect to the previous issue due to the extensiveness of the changes.” However, there are no major departures from MIL‑STD‑464A. There are some additional requirements and changes to environment definitions, but the overall standard has the same look and feel, and if readers have worked with MIL‑STD‑464A, they will be right at home with the “B” revision. In fact, the changes are subtle and buried enough that the point of this review is to flag things that might not leap out at the reader at first glance. This review functions as the non‑existent “marginal notations.”

Aside from the contractual aspect of being the E3 discipline procurement standard, the appendix of MIL‑STD‑464B continues to be where the really good lessons‑learned type information may be found. The appendix has been significantly revised. For each main body change identified in the article, the reader is well‑advised to seek out the corresponding Appendix section(s).

Fair Warning: What follows is intended to be a comprehensive aid to the user. Making this list a “page‑turner” was well beyond the author’s meager capabilities.
So, with no further ado, and coffee cups filled, we wade in.

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A very user‑friendly feature, non‑content‑related, is that the table of contents is hyperlinked to the various sections of the document. An electronic copy of the standard is more desirable than ever. There is no hyperlink between main body and appendix material yet – leaving the user community something to look forward to in revisions yet to come…

The major additions to this revision of the standard are the high power microwave (HPM) requirement and the new requirement on unintentional emissions, about which more later. The HPM requirement is described at an unclassified level, in keeping with the unlimited distribution status of MIL‑STD‑464. The HPM environment presented in the appendix represents known threats, not what might exist at some time in the future “if present trends continue.” A second addition is a requirement levied to limit interference from co‑located Army systems. The scenario that prompted this new requirement is the side‑by‑side juxtaposition of systems not previously expected to operate side‑by‑side, such as a ground vehicle parked immediately adjacent to a Tactical Operations Center (TOC) antenna installation, or perhaps two different vehicles very close to each other in a convoy. The requirement is that placement of the culprit‑victim pair of systems at one meter separation not cause unacceptable degradation to each other’s communication abilities. The requirement is verified by bringing antennas of the sort used by the victim platform within one meter of the culprit and measuring the antenna output with an appropriate spectrum analyzer or EMI receiver for comparison to the victim radio’s noise floor. The requirement verification is borrowed from the spectrum analyzer technique already used in MIL‑STD‑464 for verifying the compatibility of radio and antenna installations on the same platform.

And now, a section‑by‑section summary of changes. Only changed sections are listed. In the list that follows, the bold section number is for MIL‑STD‑464B. If the section number is the same as it was for MIL‑STD‑464A, then it only appears once. If the number is different, then the ‑464A number appears after it in parentheses.

Section 2.2.1 in the applicable documents section adds MIL‑STD‑1605(SH), Procedures for Conducting a Shipboard Electromagnetic Interference (EMI) Survey (Surface Ships)

Section 2.2.2 in the applicable documents section adds an HPM‑related Intel report: “Information Operations Capstone Threat Assessment Report (Latest Edition)”

Section 3 is definitions. This first installment includes all the new or changed definitions in Section 3. The next installment will continue on with Section 4, General Requirements, and Section 5, Detailed Requirements.”

(Section 3.1) The MIL‑STD‑464A definition “Above Deck: An area on ships, which is directly exposed to the external electromagnetic environment, and is not considered to be below deck as defined herein,” is replaced by the more general Section 3.27 “Topside Area” definition in Section 3.27: “All shipboard areas continuously exposed to the external electromagnetic environment, such as the main deck and above, catwalks, and those exposed portions of gallery decks.”

Section 3.4 (3.5) The definition of Electromagnetic Environmental Effects is expanded to include electronic protection, HPM, and ultra‑wideband devices.

Section 3.5 is new: a definition for HERO Safe Ordnance: “Any ordnance item that is sufficiently shielded or otherwise so protected that all electrically initiated devices (EIDs) contained by the item are immune to adverse effects (safety or reliability) when the item is employed in the radio frequency environment delineated in MIL‑STD‑464. The general hazards of electromagnetic radiation to ordnance requirements defined in the hazards from electromagnetic radiation manuals must still be observed. Note: Percussion‑initiated ordnance have no HERO requirements.

Section 3.6 is new: a definition for HERO Susceptible Ordnance: “Any ordnance item containing electro‑explosive devices proven by test or analysis to be adversely affected by radio frequency energy to the point that the safety and/
or reliability of the system is in jeopardy when the system is employed in the radio frequency environment delineated in MIL‑STD‑464.

Section 3.7 is new: a definition for HERO Unsafe Ordnance: “Any ordnance item containing electrically initiated devices that have not been classified as HERO SAFE or HERO SUSCEPTIBLE ordnance as a result of a hazard of electromagnetic radiation to ordnance (HERO) analysis or test. Additionally, any ordnance item containing electrically initiated devices (including those previously classified as HERO SAFE or HERO SUSCEPTIBLE ordnance) that has its internal wiring exposed; when tests are being conducted on that item that result in additional electrical connections to the item; when electrically initiated devices having exposed wire leads are present and handled or loaded in any but the tested condition; when the item is being assembled or disassembled; or when such ordnance items are damaged causing exposure of internal wiring or components or destroying engineered HERO protective devices.”

Section 3.8 is new: a definition for HPM: “A radio frequency environment produced by microwave sources (weapon) capable of emitting high power or high energy densities. The HPM operating frequencies are typically between 100 MHz and 35 GHz, but may include other frequencies as technology evolves. The source may produce microwaves in the form of a single pulse, repetitive pulses, pulses of more complex modulation, or continuous wave (CW) emissions.”

Section 3.18 is new: a definition for platform: “ A mobile or fixed installation such as a ship, aircraft, ground vehicles and shelters, launch‑space vehicles, shore or ground station. For the purposes of this standard, a platform is considered a system.”

Section 3.19 (3.15) adds a sentence at the end of the definition of Safety Critical: “A term also used when a failure or malfunction of a system or subsystem can cause death or serious injury to personnel.”

Section 3.20 is new: a definition for Shielded Area: “An area not directly exposed to EM energy. This includes shielded spaces, compartments and rooms; areas inside the hull and superstructure of metallic hull ships; areas inside metallic shelters, a metallic enclosure or a metallic mast; and areas in screen rooms on nonmetallic hull ships.”

Section 3.21 is new: a definition for Spectrum‑dependent systems: “All electronic systems, subsystems, devices, and/or equipment that depend on the use of the spectrum to properly accomplish their function(s) without regard to how they were
acquired (full acquisition, rapid acquisition, Joint Concept Technology Demonstration, etc.) or procured (commercial off‑the‑shelf, government off‑the‑shelf, non‑developmental items, etc.).

Section 3.23 is new: a definition for Subsystem: “A portion of a system containing two or more integrated components that, while not completely performing the specific function of a system, may be isolated for design, test, or maintenance. Either of the following are considered subsystems for the purpose of establishing EMC requirements. In either case, the devices or equipments may be physically separated when in operation and will be installed in fixed or mobile stations, vehicles, or systems.

a. A collection of devices or equipments designed and integrated to function as a single entity but wherein no device or equipment is required to function as an individual device or equipment.

b. A collection of equipment and subsystems designed and integrated to function as a major subdivision of a system and to perform an operational function or functions. Some activities consider these collections as systems; however, as noted above, they will be considered as subsystems.

Section 3.24 is new: a definition for System: “A composite of equipment, subsystems, skilled personnel, and techniques capable of performing or supporting a defined operational role. A complete system includes related facilities, equipment, subsystems, materials, services, and personnel required for its operation to the degree that it can be considered self‑sufficient within its operational or support environment. See 3.18.”  favicon

Ken Javor has worked in the EMC industry for thirty years. He is a consultant to government and industry, runs a pre-compliance EMI test facility, and curates the Museum of EMC Antiquities, a collection of radios and instruments that were important in the development of the discipline, as well as a library of important documentation. Mr. Javor is an industry representative to the Tri-Service Working Groups that write MIL-STD-464 and MIL-STD-461. He has published numerous papers and is the author of a handbook on EMI requirements and test methods. Mr. Javor can be contacted at ken.javor@emccompliance.com.

 

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