There is a phenomena that is sometimes seen during the Radiated Immunity Test (IEC61000-4-3) where the EUT will fail as the frequency changes to the next step but if you dwell on that frequency and turn the RF on and off it doesn't fail.
>From previous discussions on this email group some experts believe that >phenomena occurs because the Signal Generator glitches during a frequency or >power level change causing the failure which would be a false failure but >inherent to most such test equipment. Others believe that some electronics can >be more sensitive to a frequency change than a power level change and that the >failure is a real failure. I'm also learning that many test labs are coming up with their own test methods to improve the inherent uncertainties. Here are a few I'm aware of: 1. Level at each frequency using the forward power value with modulation turned off. Once leveled, turn modulation on for the dwell time. 2. Ramp down the power, change to the next frequency, then ramp it up to the value determined during calibration. 3. Reduce power by 5db, change to the next frequency, then increase power to cal value. 4. Reduce power by 5db, change frequency, read forward power value, calculate next power level and apply. I'm sure there are other methods being used. One downside to any method other than the straight forward "change frequency and power method", it adds time to the test. Customers don't like paying for extra lab time. Another issue is if a Customer fails at one lab and then goes to another lab, they may get different results if a different test method is being used. Finally, here are my questions. What test methods do you use in your lab or used by 3rd party labs that you go to? Is it common for labs to offer more than one test method depending on the pros and cons presented for each? Is there a preferred method being used? I apologize for bringing this subject up again, but I was hoping to get some updated perspective and latest opinions regarding this subject. I know every lab wants to do the best job possible and make improvements by varying the test method, but then you may introduce differences where you no longer correlate your results with other labs. I'm interested in hearing what others think on this topic. Thanks, The Other Brian ________________________________ LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - ---------------------------------------------------------------- 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://www.ieee-pses.org/list.html (including how to unsubscribe) 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>
