And similarly, not because of MU but because of 17025 or perhaps ISO 9000, I’ve seen test equipment that could easily have been calibrated in house, such as current probes, LISNs and a 41 inch rod antenna have to be sent to the calibration lab. This is totally unproductive, except for the calibration lab. And I would argue further that it is detrimental to the discipline, because if you do your own calibration, you understand better how things work.
Oh, and my favorite, the calibration of microwave horn antennas, whose properties are entirely set by their linear dimensions. The measurement or verification that their dimensions have not changed since their original acquisition is so much more accurate than the direct measurement of their gain. In fact any passive antenna used in the EMI measurement business can be easily checked visually for dimensional abnormalities, and those with a balun, such as a dipole, biconical or logperiodic can be checked for vswr using a directional coupler; no need for expensive and time consuming annual or semi-annual trips to a calibration facility. If it isn’t physically damaged, and the vswr meets original specs, meaning the balun is good, the antenna is good. Ken Javor Phone: (256) 650-5261 ________________________________ From: Cortland Richmond <[email protected]> Reply-To: <[email protected]> List-Post: [email protected] List-Post: [email protected] List-Post: [email protected] Date: Thu, 12 Aug 2010 07:24:17 -0400 To: emc-pstc <[email protected]> Subject: Re: Calibration supplier for signal generator with pulse modulation A tangential issue: those who rely on that algorithmic process often don't know why certain things are required and others left unsaid. I've see a manager forbid using a high-pass filter during CE testing because it appeared nowhere in a standard's setup drawings. Demonstration was required! Cortland KA5S ----- Original Message ----- From: Ken Javor <mailto:[email protected]> <mailto:[email protected]> To: Untitled <mailto:[email protected]> <mailto:[email protected]> Sent: 8/11/2010 1:04:51 PM Subject: Re: Calibration supplier for signal generator with pulse modulation Bingo. Clearly another driver for inserting MU where it doesn't belong is a desire to replace the need for competent personnel with an algorithmic process that works for any personnel. But the same personnel who don‚t know how to properly perform the test will also not know how to run the algorithm. Hence Mr. Walton‚s observations on how poorly MU is executed in reality. Ken Javor Phone: (256) 650-5261 ________________________________ From: Dennis Ward <[email protected]> Reply-To: <[email protected]> Date: Wed, 11 Aug 2010 09:50:21 -0700 To: <[email protected]>, <[email protected]>, <[email protected]> Subject: RE: Calibration supplier for signal generator with pulse modulation I think I would only add that while measurement uncertainties for EMC is nebulous at best, at the same time we do not want to get into the habit of a slam dunk mentality of Œoh, just a number, it doesn‚t matter.‰ That is why Derek‚s statement of „What‚s really needed is a competent individual with adequate equipment‰ is so important. Where electromagnetic compatibility is concerned, competence of the engineers doing the measurement is probably much more importa! nt than uncertainties. I know that one of the biggest benefits to testing in the radio approvals industry is competence of test personnel. Compliance does matter and the best way to keep unneeded uncertainties out of the EMC measurement industry, is to keep competence of test personnel in. Dennis Ward Director of Engineering American TCB Certification Resource for the Wireless Industry www.atcb.com <http://www.atcb.com/> <http://www.atcb.com/> 703-847-4700 fax 703-847-6888 direct - 703-880-4841 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ 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]> - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ 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]>
