AUTHOR’S NOTE
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.
This is Part 2 of 3 parts of a review of the newly released MIL‑STD‑464C, “Electromagnetic Environmental Effects Requirements for Systems.” The following is a summary of Part 1 of the review, then on to new material.
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‑464C 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 & C revisions of MIL‑STD‑464 amend the original release but are evolutionary, not revolutionary changes. MIL‑STD‑464C 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 “C” 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‑464C 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).
Part 1 of the review gave a broad‑brush treatment to what was new in the standard, the high power microwave requirement and the co‑located systems compatibility requirement, and then went through Section 3 definitions and listed all the changes.
We pick up with changes to Section 4 and then move on to Section 5. This part of the review ends with Section 5.3, which is the electromagnetic environment tables. Part 3 will pick up where Part 2 leaves off, with Section 5.4, High Power Microwave.
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‑464C. 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 4.1, General Requirements, has been greatly expanded. The ‑464A and ‑464C versions are shown side‑by‑side in Table 1.
Table 1
Section 5.2 Intra‑system EMC adds this statement to the heritage ‑464A requirement: “For surface ships, MIL‑STD‑1605(SH) provides test methods used to verify compliance with the requirements of this standard for intra‑ and inter‑system EMC, hull generated intermodulation interference, and electrical bonding.” Stressing here what was mentioned earlier, the appendix to this section has much new information and some rearrangement.
Section 5.2.1 Hull‑generated intermodulation interference (IMI) contains a bit of a sleeper change: The requirement is changed from controlling IMI products of 19th order and higher (in ‑464A) to above the 19th order in ‑464C.
Section 5.2.2 Shipboard internal electromagnetic environment (EME) adds verbiage related to the use of wireless systems below decks, which is a growing trend. Such sources can be Wi‑Fi, RFID systems, handheld communications, and other low‑power transmitters. Also, the EME for non‑metallic ships has been raised to 50 V/m below 2 MHz, from a previous requirement of 10 V/m. The submarine EME above 30 MHz has been raised from a previous level of 5 V/m to 10 V/m in ‑464C.
Section 5.2.4 is a new section entitled, “Induced levels at antenna ports of antenna‑connected receivers.” This section basically brings an excellent verification technique that resided in the appendix in MIL‑STD‑464 and MIL‑STD‑464A into the requirements main body in MIL‑STD‑464C. Sections of the appendix that dealt with spectrum analyzer surveys of platform antennas in A5.2 have been moved to the A5.2.4 part of the appendix.
Section 5.3 External EME has updated tables and lots of new appendix material. The Table numbering scheme has changed from 1A, 1B, etc. to Roman numerals. Thus Tables 1A‑F in ‑464A now comprise Tables I‑VI in ‑464C. In general, changes to the table vary by frequency range. The changing entries reflect updates to MIL‑HDBK‑235 and are unclassified versions of detailed tables in that handbook. In the following annotated tables, the new ‑464C values are shown first, the old ‑464A values second, where different. Color coding: Red fill means level has increased. Yellow fill means change is less than 1 dB, either higher or lower, and blue highlight means ‑464C level is lower than for ‑464A. * means no emitters in that frequency range.
Color coding: Red fill means level has increased. Yellow fill means change is less than 1 dB, either higher or lower, and blue highlight means ‑464C level is lower than for ‑464A. * means no emitters in that frequency range.
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.
