Requiring the unintentional limits for intentional radiators to be lower reduces the chance intermod products being radiated.
Mark S. Luksich DMTS - Regulatory Engineering Office: 631-738-5134 Mobile: 631-827-9385 Fax: 631-738-3776 e-mail: mark.luks...@motorola.com From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Haynes, Tim (SELEX GALILEO, UK) Sent: Wednesday, January 07, 2009 5:59 AM To: Andrew McCallum; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: FCC Part 15.109 and 15.209 Radiated emission limits Hi Andy, In the UK it is the same. Developers of radio equipment are required to suppress the harmonic and spurious radiated emission levels to a level lower than the general radiate emission limits given for domestic environments [for most of the spectrum, this is true - there are some exceptions] The only reason I have ever been given, is that radio designers have (or should have) the knowledge and test equipment to achieve these levels AND because the equipment is likely to be connected to an antenna mounted at a reasonable height above ground. The general requirement is applied to non-radio equipment, where the designer might not have the knowledge or the equipment to achieve the lower levels. Since the equipment is likely to be used at a normal height, not normally connected to an antenna and normally used inside a building [a lot of generalisation on my part here] the permitted levels will actually have a lower risk of causing interference to radio systems. I do not know if the same logic has been applied in America but it might have been. Regards Tim ************************ Tim Haynes A1N10 Electromagnetic Engineering Specialist SELEX Sensors and Airborne Systems 300 Capability Green Luton LU1 3PG ( Tel : +44 (0)1582 886239 7 Fax : +44 (0)1582 795863 ) Mob : +44 (0)7703 559 310 * E-mail : tim.hay...@selexgalileo.com P Please consider the environment before printing this email. There are 10 types of people in the world-those who understand binary and those who don't. J. Paxman ________________________________ From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Andrew McCallum Sent: Wednesday, January 07, 2009 10:44 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: FCC Part 15.109 and 15.209 Radiated emission limits *** WARNING *** This mail has originated outside your organization, either from an external partner or the Global Internet. Keep this in mind if you answer this message. Happy new year all Can anyone explain why an unintentional radiator is allowed to have higher emission limits than an intentional radiator. By design you would hope that spurious emissions from an intentional radiator would be lower but why have two different limits? Any help much appreciated. regards Andy ________________________________ Confidentiality: This e-mail and its attachments are intended for the addressees only (or people authorised to receive them on their behalf) and may be confidential or privileged. 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