Over the past couple of weeks, I have been looking at how Japan defines their terms of "necessary" and "occupied" bandwidth for intentional emitters. When I went to compare this with how the US military uses 461E to define these same concepts, I was surprised that there doesn't seem to be a technical definition in MIL-STD-461E. Method CE106, Paragraph 5.6.1 states "The transmit mode portion of this requirement is not applicable within the EUT necessary bandwidth and within ±5 percent of the fundamental frequency.". (Method RE103, Paragraph 5.17.1 is similar.) OK, so what is the "necessary" bandwidth? Is this the 99% energy content spectrum? Is it the -80 dBc points? Looking around at possibly "higher" levels of authority, I notice that the NTIA May 2004 edition of Manual of Regulations and Procedures for Federal Radio Frequency Management contains a definition. Paragraph 6.3.2 almost defines "necessary" bandwidth, but then refers you to Annex J. Annex J, Paragraph 2.1 provides formulae for a number of specific modulations, but it also includes "best technical information from other sources" and a reference to ITU-R SM.328-8 (1994) and SM.853 (1994). OK, I'm still reading this Annex J (and it's Table A formulae), but do you think that I have made a reasonable assumption in using NTIA definitions for MIL-STD-461E? Ed Price <mailto:[email protected]> [email protected] WB6WSN NARTE Certified EMC Engineer & Technician Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (FAX) Military & Avionics EMC Is Our Specialty
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