Yet how far would you take that argument? If it's say 11.1db at 110MHz and 11.5dB at 112MHz, would you still worry about factor at 111MHz? At some point surly this all becomes rather silly. _____________________________________________________________________________________
Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: "ce-test, qualified testing bv - Gert Gremmen" <g.grem...@cetest.nl> To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/05/2011 10:06 PM Subject: Re: [PSES] Calibration practice for EMI test transducers If at 100 MHz your sensor indicates during calibration 10 dB and at 120 MHz 12 dB, how are you going to know the value at 110 MHz. It maight be 20 as well as 0 dB, you don't not know as you did not measure/ calibrate. This requires some knowledge about the behavior of the sensor, and the 1/BW is and indication of that. There is another aspect in EMI measurements. As the measuring receiver interpolates between the calibrated samples, the max interpolation error (lin interpolation) is 50% of the vertical differences between calibration points. If the measuring receiver is +/- 0.5 dB you should register a calibration each time the difference between previous and current sample is 0.5 dB. Then the total error will be slightly more than 0.5 dB. There are more sophisticated interpolation methods such as cubic spline and polynomial interpolation, and the error item is subject to higher mathematics..... Play with it at: http://terpconnect.umd.edu/~petersd/interp.html or at http://www.ibiblio.org/e-notes/Splines/Lagrange.htm you can actually move the points on the latter page. Gert Gremmen -----Oorspronkelijk bericht----- Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens Cortland Richmond Verzonden: dinsdag 6 december 2011 3:01 Aan: emc-p...@ieee.org Onderwerp: RE: Calibration practice for EMI test transducers I recently had occasion to verify on an 8591EM generic factors for an EMCO current clamp during pretest, and used its tracking generator to see if with a short wire the result was a straight line on the screen. That simply called for paying attention to 1/BW. Cortland KA5S On 12/5/2011 5:33 PM, Ken Javor wrote: If an antenna, current probe or other transducer is going to be calibrated over its frequency range of operation, what determines the step sizes between measured frequencies, or if swept, what determines the density of test points reported? - ---------------------------------------------------------------- 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 <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. 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 <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com> - ---------------------------------------------------------------- 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 <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. 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 <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com> ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. ______________________________________________________________________ - ---------------------------------------------------------------- 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 <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. 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 <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
