Well , 300 meters with that limit is ridiculous, and 30 meters I am sure sure the ITE device will pass. You must be intentional
radiator to get a field strength like that a 30 meters. As for most of the spectrum you are in the close field range, the intensity of the field will decay with the inverse square or inverse third power of the distance, so measuring distance is of utmost importance. I have been carrying out the tests at 1 meter and at 3 meters on ordinary equipment such as GPS receivers and associated equipment, and even on CRT displays. I never got even close to the limit. To see any signal one has to put the equipment within the loop. Most peculiar is that there is no requirement for orientation of the loop. Gert Gremmen Van: [email protected] [mailto:[email protected]] Namens Bill Owsley Verzonden: donderdag 16 oktober 2008 17:46 Aan: [email protected]; Amund Westin Onderwerp: RE: IEC 60945 & computer equipment onboard ships The FCC measuring distance for radiated emissions in that freq range is 300 meters and 30 meters. As usual, other measuring distances are allowed and corrections made to either move the limit to the measured distance or move measurement to the limit distance. There are certain advantages hidden within the correction process. - Bill Indecision may or may not be the problem. --- On Thu, 10/16/08, Amund Westin <[email protected]> wrote: From: Amund Westin <[email protected]> Subject: RE: IEC 60945 & computer equipment onboard ships To: [email protected] Date: Thursday, October 16, 2008, 11:11 AM I thought that the default measuring distance was 3 meter, even in the 150kHz – 30MHz band. Fra: [email protected] [mailto:[email protected]] På vegne av Gert Gremmen Sendt: 16. oktober 2008 15:44 Til: [email protected] Emne: RE: IEC 60945 & computer equipment onboard ships The limit of 24 dBuV QP should be measured with a bandwidth of 9 kHz, a combination that is not too common (I mean QP and 9 kHz BW)in measuring receivers but the newest. Alternately 30 dBuV peak may be applied, and then 9 (10) kHz is a normal setting. 60945 also requires 1-2 GHz emission testing with a BW of 120 kHz, where normal EMC standards require 1 MHz bandwidth. As a last pitfall, magnetic emissions are required from 150 KHz to 30 MHz, this requires a 60 cm loop. Fortunately (!!?!!) the standard has no test set-up requirements for this test set up, nor test distance is specified. BTW if someone has some reference sources to this rather old test method (60 cm loop: history, calibration or other), I would be obliged if he would share this with the list. Regards, Ing. Gert Gremmen ce-test, qualified testing bv Van: [email protected] [mailto:[email protected]] Namens Amund Westin Verzonden: Thursday, October 16, 2008 2:45 PM Aan: [email protected] Onderwerp: RE: IEC 60945 & computer equipment onboard ships >From IEC60945 scope: This standard specifies minimum performance requirements, methods of testing and required test results for general requirements which can be applied to those characteristics common to all equipment described hereunder: c) for EMC only, all other bridge-mounted equipment, equipment in close proximity to receiving antennas, and equipment capable of interfering with safe navigation of the ship and with radio-communications (see IMO Resolution A.813). So, ITE placed on bridge is basically covered by the standard. Be aware that radiated emission in the band 156-165MHz has a limit of 24dBuV/m. A lot of equipment fails at that point. #Amund Fra: [email protected] [mailto:[email protected]] På vegne av [email protected] Sendt: 16. oktober 2008 13:09 Til: [email protected] Emne: IEC 60945 & computer equipment onboard ships Does anybody have any experience with EMC testing to IEC 60945 ? The scope of the standard mentions that EMC requirements apply to ‘all other equipment’ (ie non-navigational or radio communication equipment). Does this cover computer equipment and if so is 60945 more onerous than CISPR 22/24 used for ITE ? The scope also mentions that radio equipment and navigation equipment be type-approved by national administrations . I presume that computing equipment not part of radio/navigation equipment does not require type approval but would be interested in hearing your thoughts on this also. Thanks for your help Brian McAuliffe Dell Products Europe - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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