Ed's interpretation is the same as mine. Necessary bandwidth is defined by the radio performance specification - it is the higher authority. And clearly the necessary bandwidth is the -80 dBc bandwidth, because that is the limit, except at the second and third harmonic, where there is possible relief depending on the output power. -- Ken Javor
Phone: (256) 650-5261 From: "Price, Ed" <[email protected]> List-Post: [email protected] Date: Fri, 10 Aug 2007 21:19:41 -0700 To: "IEEE EMC Discussion Group" <[email protected]> Subject: MIL-STD-461E Necessary Bandwidth 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 [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 - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________ - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
