Re: [PSES] Calibration practice for EMI test transducers
Hello Gert, It was Ken Javor who was asking, but I will note that ETS-Lindgren probe documents specify an accuracy of +/- 2 dB transfer impedance, which for *formal* calibration requires as you say 0.5 dB accuracy. It also takes precision 50 Ohm test fixtures, better loads that I used, and a better instrument, too. Call my process a sanity check, adequate only to get an ad-hoc setup back to readings that more closely approximate what was seen at outside test houses. That's what the customer wanted. However, any deviation from a smooth response may be detected fairly easily, and if I saw a jog in a current probe function I would recommend replacement. I did recommend the customer get their analyzer and probe calibrated. Regards, Cortland Richmond KA5S On 12/6/2011 1:03 AM, ce-test, qualified testing bv - Gert Gremmen wrote: 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 athttp://www.ibiblio.org/e-notes/Splines/Lagrange.htm you can actually move the points on the latter page. Gert Gremmen - 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
Re: [PSES] USB powered Lithium Battery Charger
My bad, dc-only input not scoped for UL1310. Brian -Original Message- From: Brian Oconnell [mailto:oconne...@tamuracorp.com] Sent: Monday, December 05, 2011 2:23 PM To: 'IEEE PSES' Subject: RE: USB powered Lithium Battery Charger Messy answer to difficult question. I have had some interesting conversations with several different agency engineers; that is, no agreement; so just tell them which standard to use. USB cannot always be considered LPS IAW 60950/2.5, so would test as 'dc mains' device. Most NRTLs will gladly take your money and certify as an 'ITE Power Supply'. If any part of output power exposed to user, or if outputs of your charger must be class 2 - UL1310/CSA223, otherwise you could use UL1012 if you did not want to use 60950-1. Carefully read scope clause for 60335-2-29, may not be applicable to your device. Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Peter Merguerian Sent: Monday, December 05, 2011 1:24 PM To: IEEE PSES Subject: USB powered Lithium Battery Charger Dear All For a 5 vdc USB powered lithium battery charger, is iec 60950-1 the appropriate safety standard or iec 60335-2-29? The charger is intended to charge the battery located on a bicycle frame. Also, what are the applicable North American and EU standards applicable for this battery charger? Thanks, Peter - 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
[PSES] Average detector/s
Quasi-peak was fun, so now let's have fun with the Average detector/s, each and all of them ! For reference, EN 302 208-1, Sec. 8.3, 8.4, 8.5. Detection mode: Averaging Which averaging would this be? On the SA that I'm using, There is video averaging by reducing the VBW to something a lot smaller than RBW. There is EMI average detector, and There is average detector which has two modes, power and video. (one is the log of the average of power, the other is the average of the log of power.) And there is a multiple sweep averaging of the above. And there is adjusting the sweep time while averaging is turned on. And adjusting the span to be measured has an effect on the average measurement. Each can give a different result. So starting with the always correct answer in EMC, it depends, what are these dependencies? - 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
Re: [PSES] Average detector/s
For in-house pre-compliance testing, we use a VBW of 10Hz to approximate the time response of an AVG detector. Seems to work quite well. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: Bill Owsley wdows...@yahoo.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 09:15 AM Subject: [PSES] Average detector/s Quasi-peak was fun, so now let's have fun with the Average detector/s, each and all of them ! For reference, EN 302 208-1, Sec. 8.3, 8.4, 8.5. Detection mode: Averaging Which averaging would this be? On the SA that I'm using, There is video averaging by reducing the VBW to something a lot smaller than RBW. There is EMI average detector, and There is average detector which has two modes, power and video. (one is the log of the average of power, the other is the average of the log of power.) And there is a multiple sweep averaging of the above. And there is adjusting the sweep time while averaging is turned on. And adjusting the span to be measured has an effect on the average measurement. Each can give a different result. So starting with the always correct answer in EMC, it depends, what are these dependencies? __ 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 - 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
Re: [PSES] Calibration practice for EMI test transducers
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
[PSES] Product Safety Engineer Position in Frederick, MD
We are seeking candidates for Product Safety Engineer at our laboratory in Frederick, MD. Contact Mike Violette or Steve Ferguson ste...@wll.com. Job Description Senior-level experienced product safety engineer to help grow and develop our operations in Frederick, Maryland. • Support solving test-related problems • Support test planning activities • Review compliance test data • Perform duties of Compliance Engineer as required • Coordinate project equipment scheduling • Conduct Compliance Engineer training • Support clients on problem resolution • Generate quotes Desired Skills Experience minimum education requirement of B.S. in Electrical Engineering or equivalent Minimum of 5 years experience in Product Safety/Compliance Engineering Detailed knowledge of 61010, 60950 and related safety requirements, including IEC standards and the CB scheme Knowledge of ISO 17025 and third party safety agency test data acceptance programs Excellent communication skills and problem solving abilities A self-starter with the ability to work independently Company Description Electromagnetic Compatibility (EMC), Electromagnetic Interference (EMI), Radio Frequency (RF) and Product Safety testing, Environmental testing, and EMC compliance engineering. Expert and timely solutions for Product Testing and Approvals, Wireless Certification, Federal Communications Commission (FCC), Underwriters Laboratories (UL), CE Marking, Canadian Standards (CSA), ICES, RSS, TUV, and the CB Scheme. Our test lab locations in Maryland (Frederick and Gaithersburg) provide convenience to EMC, product safety and environmental customers throughout the East. Additional Information Posted: December 6, 2011 Type: Full-time Experience: Mid-Senior level Functions: Engineering Industries: Electrical/Electronic Manufacturing Compensation: Competitive, commensurate w/ experience Mike Violette Washington Laboratories American Certification Body mi...@wll.com +1 240 401 1388 - 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
Re: [PSES] Average detector/s
If video averaging is done with a log amplifier instead of linear, then a geometric mean is taken rather than an arithmetic mean, the latter being an average detector. Both means naturally yield the same output with a cw input, but as the variation in the averaged quantities gets greater (standard deviation increases) the difference between the two types of means gets larger and larger. Hence, for an intermittent broadband signal of high amplitude but very low duty cycle and duration, one would expect very different outputs when using the log display vs. linear. Ken Javor Phone: (256) 650-5261 From: ralph.mcdiar...@schneider-electric.com Date: Tue, 6 Dec 2011 11:15:40 -0800 To: Bill Owsley wdows...@yahoo.com Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Average detector/s For in-house pre-compliance testing, we use a VBW of 10Hz to approximate the time response of an AVG detector. Seems to work quite well. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: Bill Owsley wdows...@yahoo.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 09:15 AM Subject: [PSES] Average detector/s Quasi-peak was fun, so now let's have fun with the Average detector/s, each and all of them ! For reference, EN 302 208-1, Sec. 8.3, 8.4, 8.5. Detection mode: Averaging Which averaging would this be? On the SA that I'm using, There is video averaging by reducing the VBW to something a lot smaller than RBW. There is EMI average detector, and There is average detector which has two modes, power and video. (one is the log of the average of power, the other is the average of the log of power.) And there is a multiple sweep averaging of the above. And there is adjusting the sweep time while averaging is turned on. And adjusting the span to be measured has an effect on the average measurement. Each can give a different result. So starting with the always correct answer in EMC, it depends, what are these dependencies? __ 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 mailto:emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html 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/ http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net mailto:emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org mailto:mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org mailto:j.bac...@ieee.org David Heald dhe...@gmail.com mailto: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 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/
Re: [PSES] Average detector/s
Bill- Seeing as how I am seldom at a loss for words in technical matters, even when I am dead wrong, let me take a whack at this. So far as I know, the averaging is a 1 Hz post-detection filter (1 Hz video bandwidth), single pole, i.e., an RC filter with a 1 Hz corner frequency (or the digital equivalent). To do it right, the averaging should be done on a linear signal (e.g., on the detected signal BEFORE going through the log amp, not after. You could still display the results in a log display, so the log amp could be applied to the signal after the average filter. Side note: When measuring the average amplitude of Gaussian white noise, the narrow video filter needs to be before the log amp. If the filtering is done after the log amp, the noise power will read low by about 2.3 dB (if I remember correctly). This is because the statistics (distribution) of Gaussian noise are different from the statistics of the log of Gaussian noise. I don't recall if the meter is specified for average measurement, as it is for the quasi-peak measurement. Even if it is, I would think that the average signal is slow enough that the funky dynamics of the meter don't really come into play. Note: I use the phrase log amp because classical log amps are seldom used now. The log display in modern spectrum analyzers is generated using data from A/D converters, with the log function done in computer code. I suspect that your EMI average detector is a preset that gives you the 1 Hz post detection filter and then runs the signal to the log amp The multiple sweep average would probably give the same answer if the average were of the signal before the log amp, assuming that there are no amplitude variations in the signal with frequencies approaching 1 Hz from the high side. Of course, this is not how the standard is written. And if the signal does have amplitude variations approaching 1 Hz, then you will get different readings with the conventional average measurement. Also, one would need to carefully specify how the multisweep average is done. The usual algorithm is an exponentially decaying contribution from older sweeps, with the number of sweeps in the decay sequence usually set-able by the user. I am not exactly sure how one would go about selecting this to result in a response equivalent to a 1 Hz video filter. The sweep rate will be generally be reduced when the 1 Hz video filter is selected. Sweep rates are set by the spectrum analyzer to make sure that ALL the filters, both IF and post detection, have time to respond fully when sweeping through a signal. Donald Borowski Schweitzer Engineering Labs Pullman, Washington, USA From: Bill Owsley wdows...@yahoo.com To: EMC-PSTC@LISTSERV.IEEE.ORG EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 09:17 AM Subject:Average detector/s Sent by:emc-p...@ieee.org Quasi-peak was fun, so now let's have fun with the Average detector/s, each and all of them ! For reference, EN 302 208-1, Sec. 8.3, 8.4, 8.5. Detection mode: Averaging Which averaging would this be? On the SA that I'm using, There is video averaging by reducing the VBW to something a lot smaller than RBW. There is EMI average detector, and There is average detector which has two modes, power and video. (one is the log of the average of power, the other is the average of the log of power.) And there is a multiple sweep averaging of the above. And there is adjusting the sweep time while averaging is turned on. And adjusting the span to be measured has an effect on the average measurement. Each can give a different result. So starting with the always correct answer in EMC, it depends, what are these dependencies? - 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
Re: [PSES] Calibration practice for EMI test transducers
This discussion has gone far a field from the original post. I¹m assuming some sort of scan has been run and a continuous sweep is available. The question is, how densely does that sweep need to be digitized? Not as a practical matter, but as a matter of compliance with standards or standard practice. What manner of antenna would have performance as cited below where at 100 MHz the antenna factor is 10 dB and at 120 MHz it is 12 dB, but at 110 MHz it could be 20 dB? Let¹s generalize the question to any closely spaced frequencies. Let¹s look at the types of antennas available. 30-200 MHz: A half-wave tuned dipole is nowhere near that sharp. Neither is a biconical. 200 1000 MHz: A half-wave tuned dipole is nowhere near that sharp. Neither is a logperiodic, log-spiral, nor a Yagi. 1 GHz+: Logperiodic, log-spiral nor pyramidal horns act the way surmised. My conclusion, and the point here is to invite discussion, not close it out, is that no test-type antenna is a high ³Q² device. Antennas can have arbitrarily high gains, depending on construction, but the high gain is a geometrical quality, not a high quality factor in the frequency domain. Ken Javor Phone: (256) 650-5261 From: ralph.mcdiar...@schneider-electric.com Date: Tue, 6 Dec 2011 11:25:43 -0800 To: ce-test, qualified testing bv - Gert Gremmen g.grem...@cetest.nl Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Calibration practice for EMI test transducers 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 http://terpconnect.umd.edu/~petersd/interp.html or at http://www.ibiblio.org/e-notes/Splines/Lagrange.htm 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 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 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/ http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott
Re: [PSES] Average detector/s
Yes, you need to put it in linear mode before making a true (arithmetic) average measurement. But just to discern whether a signal is BB or NB, averaging using the log amp works just fine. Ken Javor Phone: (256) 650-5261 From: ralph.mcdiar...@schneider-electric.com Date: Tue, 6 Dec 2011 14:05:00 -0800 To: Ken Javor ken.ja...@emccompliance.com Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Average detector/s The HP8568B we use here displays amplitude in 10dB increments, so I assume that means a log amplifier after the detector? (the amplifier driving the vert deflection responds to the logarithm of the signal level) _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: Ken Javor ken.ja...@emccompliance.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 01:45 PM Subject: Re: [PSES] Average detector/s If video averaging is done with a log amplifier instead of linear, then a geometric mean is taken rather than an arithmetic mean, the latter being an average detector. Both means naturally yield the same output with a cw input, but as the variation in the averaged quantities gets greater (standard deviation increases) the difference between the two types of means gets larger and larger. Hence, for an intermittent broadband signal of high amplitude but very low duty cycle and duration, one would expect very different outputs when using the log display vs. linear. Ken Javor Phone: (256) 650-5261 From: ralph.mcdiar...@schneider-electric.com Date: Tue, 6 Dec 2011 11:15:40 -0800 To: Bill Owsley wdows...@yahoo.com Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Average detector/s For in-house pre-compliance testing, we use a VBW of 10Hz to approximate the time response of an AVG detector. Seems to work quite well. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: Bill Owsley wdows...@yahoo.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 09:15 AM Subject: [PSES] Average detector/s Quasi-peak was fun, so now let's have fun with the Average detector/s, each and all of them ! For reference, EN 302 208-1, Sec. 8.3, 8.4, 8.5. Detection mode: Averaging Which averaging would this be? On the SA that I'm using, There is video averaging by reducing the VBW to something a lot smaller than RBW. There is EMI average detector, and There is average detector which has two modes, power and video. (one is the log of the average of power, the other is the average of the log of power.) And there is a multiple sweep averaging of the above. And there is adjusting the sweep time while averaging is turned on. And adjusting the span to be measured has an effect on the average measurement. Each can give a different result. So starting with the always correct answer in EMC, it depends, what are these dependencies? __ 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 mailto:emc-p...@ieee.org mailto:emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html http://www.ieee-pses.org/emc-pstc.html http://www.ieee-pses.org/emc-pstc.html 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/ http://product-compliance.oc.ieee.org/ http://product-compliance.oc.ieee.org/ http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ http://www.ieee-pses.org/ http://www.ieee-pses.org/ http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html http://listserv.ieee.org/request/user-guide.html http://listserv.ieee.org/request/user-guide.html http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html http://www.ieee-pses.org/listrules.html http://www.ieee-pses.org/listrules.html http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net mailto:emcp...@radiusnorth.net mailto:emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org mailto:mcantw...@ieee.org mailto:mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org mailto:j.bac...@ieee.org mailto:j.bac...@ieee.org David Heald
Re: [PSES] Average detector/s
Indeed it does. The measured signal in this particular case is broadband stuff of a modulated carrier. So far I can get a 20 dB spread when measuring the signal with all the different buttons and techniques available for average. And you know the limit falls right in the middle !! And the fingers start pointing... The instrument manual says the average detector finds the average of everything in each measuring window and reports that. instantaneous average ?!?! And then do a trace max hold on that, and it begins to look similar to peak. Now if I turn on averaging over time, for instance a running average of a 100 runs, The reported value settles down nicely. But, I suspect any interference has already happened. Or, If I slow the sweep time down, then the same settling occurs as each window is averaged during the measurement dwell and that number is reported. I have not found a reference to an averaging time. Is there one? From: Ken Javor ken.ja...@emccompliance.com To: EMC-PSTC@LISTSERV.IEEE.ORG Sent: Tuesday, December 6, 2011 4:43 PM Subject: Re: [PSES] Average detector/s Re: [PSES] Average detector/s If video averaging is done with a log amplifier instead of linear, then a geometric mean is taken rather than an arithmetic mean, the latter being an average detector. Both means naturally yield the same output with a cw input, but as the variation in the averaged quantities gets greater (standard deviation increases) the difference between the two types of means gets larger and larger. Hence, for an intermittent broadband signal of high amplitude but very low duty cycle and duration, one would expect very different outputs when using the log display vs. linear. Ken Javor Phone: (256) 650-5261 From: ralph.mcdiar...@schneider-electric.com Date: Tue, 6 Dec 2011 11:15:40 -0800 To: Bill Owsley wdows...@yahoo.com Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Average detector/s For in-house pre-compliance testing, we use a VBW of 10Hz to approximate the time response of an AVG detector. Seems to work quite well. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From:Bill Owsley wdows...@yahoo.com To:EMC-PSTC@LISTSERV.IEEE.ORG Date:12/06/2011 09:15 AM Subject:[PSES] Average detector/s Quasi-peak was fun, so now let's have fun with the Average detector/s, each and all of them ! For reference, EN 302 208-1, Sec. 8.3, 8.4, 8.5. Detection mode: Averaging Which averaging would this be? On the SA that I'm using, There is video averaging by reducing the VBW to something a lot smaller than RBW. There is EMI average detector, and There is average detector which has two modes, power and video. (one is the log of the average of power, the other is the average of the log of power.) And there is a multiple sweep averaging of the above. And there is adjusting the sweep time while averaging is turned on. And adjusting the span to be measured has an effect on the average measurement. Each can give a different result. So starting with the always correct answer in EMC, it depends, what are these dependencies? __ 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.orgmailto:emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.htmlhttp://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/http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.htmlhttp://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.htmlhttp://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.netmailto:emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.orgmailto:mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.orgmailto:j.bac...@ieee.org David Heald dhe...@gmail.commailto: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
Re: [PSES] Average detector/s
It certainly makes sense that if filtering (1Hz) is done in the detector, then any log amplification done thereafter shouldn't affect averaging. A good explanation Don; even I was able to follow along. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: don_borow...@selinc.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 02:03 PM Subject: Re: [PSES] Average detector/s Bill- Seeing as how I am seldom at a loss for words in technical matters, even when I am dead wrong, let me take a whack at this. So far as I know, the averaging is a 1 Hz post-detection filter (1 Hz video bandwidth), single pole, i.e., an RC filter with a 1 Hz corner frequency (or the digital equivalent). To do it right, the averaging should be done on a linear signal (e.g., on the detected signal BEFORE going through the log amp, not after. You could still display the results in a log display, so the log amp could be applied to the signal after the average filter. Side note: When measuring the average amplitude of Gaussian white noise, the narrow video filter needs to be before the log amp. If the filtering is done after the log amp, the noise power will read low by about 2.3 dB (if I remember correctly). This is because the statistics (distribution) of Gaussian noise are different from the statistics of the log of Gaussian noise. I don't recall if the meter is specified for average measurement, as it is for the quasi-peak measurement. Even if it is, I would think that the average signal is slow enough that the funky dynamics of the meter don't really come into play. Note: I use the phrase log amp because classical log amps are seldom used now. The log display in modern spectrum analyzers is generated using data from A/D converters, with the log function done in computer code. I suspect that your EMI average detector is a preset that gives you the 1 Hz post detection filter and then runs the signal to the log amp The multiple sweep average would probably give the same answer if the average were of the signal before the log amp, assuming that there are no amplitude variations in the signal with frequencies approaching 1 Hz from the high side. Of course, this is not how the standard is written. And if the signal does have amplitude variations approaching 1 Hz, then you will get different readings with the conventional average measurement. Also, one would need to carefully specify how the multisweep average is done. The usual algorithm is an exponentially decaying contribution from older sweeps, with the number of sweeps in the decay sequence usually set-able by the user. I am not exactly sure how one would go about selecting this to result in a response equivalent to a 1 Hz video filter. The sweep rate will be generally be reduced when the 1 Hz video filter is selected. Sweep rates are set by the spectrum analyzer to make sure that ALL the filters, both IF and post detection, have time to respond fully when sweeping through a signal. Donald Borowski Schweitzer Engineering Labs Pullman, Washington, USA From: Bill Owsley wdows...@yahoo.com To: EMC-PSTC@LISTSERV.IEEE.ORG EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 09:17 AM Subject:Average detector/s Sent by:emc-p...@ieee.org Quasi-peak was fun, so now let's have fun with the Average detector/s, each and all of them ! For reference, EN 302 208-1, Sec. 8.3, 8.4, 8.5. Detection mode: Averaging Which averaging would this be? On the SA that I'm using, There is video averaging by reducing the VBW to something a lot smaller than RBW. There is EMI average detector, and There is average detector which has two modes, power and video. (one is the log of the average of power, the other is the average of the log of power.) And there is a multiple sweep averaging of the above. And there is adjusting the sweep time while averaging is turned on. And adjusting the span to be measured has an effect on the average measurement. Each can give a different result. So starting with the always correct answer in EMC, it depends, what are these dependencies? - 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
Re: [PSES] Calibration practice for EMI test transducers
Original post answer from here - COST. From: Ken Javor ken.ja...@emccompliance.com To: EMC-PSTC@LISTSERV.IEEE.ORG Sent: Tuesday, December 6, 2011 5:11 PM Subject: Re: [PSES] Calibration practice for EMI test transducers Re: [PSES] Calibration practice for EMI test transducers This discussion has gone far a field from the original post. I’m assuming some sort of scan has been run and a continuous sweep is available. The question is, how densely does that sweep need to be digitized? Not as a practical matter, but as a matter of compliance with standards or standard practice. What manner of antenna would have performance as cited below where at 100 MHz the antenna factor is 10 dB and at 120 MHz it is 12 dB, but at 110 MHz it could be 20 dB? Let’s generalize the question to any closely spaced frequencies. Let’s look at the types of antennas available. 30-200 MHz: A half-wave tuned dipole is nowhere near that sharp. Neither is a biconical. 200 – 1000 MHz: A half-wave tuned dipole is nowhere near that sharp. Neither is a logperiodic, log-spiral, nor a Yagi. 1 GHz+: Logperiodic, log-spiral nor pyramidal horns act the way surmised. My conclusion, and the point here is to invite discussion, not close it out, is that no test-type antenna is a high “Q” device. Antennas can have arbitrarily high gains, depending on construction, but the high gain is a geometrical quality, not a high quality factor in the frequency domain. Ken Javor Phone: (256) 650-5261 From: ralph.mcdiar...@schneider-electric.com Date: Tue, 6 Dec 2011 11:25:43 -0800 To: ce-test, qualified testing bv - Gert Gremmen g.grem...@cetest.nl Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Calibration practice for EMI test transducers 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.htmlhttp://terpconnect.umd.edu/~petersd/interp.html or at http://www.ibiblio.org/e-notes/Splines/Lagrange.htmhttp://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.orgmailto: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.htmlhttp://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at
Re: [PSES] Average detector/s
Here is an excerpt from an old (~1983) H.P. RF measurement presentation by Siegfried Linkwitz and Al Wilcox. // Average detection is provided in the spectrum analyzer by use of the video bandwidth filters. Video (post detection) filtering provides averaging of the higher frequency components (such as noise) at the output of the envelope detector. When the video filter bandwidth is narrower than the resolution bandwidth, averaging occurs. Narrowband (e.g., CW) signals amplitudes are not affected by video filtering. For a true average, the video BW must be less than the lowest pulse repetition frequency (PRF), the frequency sweep must be slow enough to let the filters charge completely, and the spectrum analyzer must be in the linear amplitude display mode. When the analyzer is in the log amplitude display mode, video filtering greatly reduces the amplitude of impulsive and random broadband signals. This is useful for measuring lower level narrowband signals in the presence of higher level impulsive signals. The amplitude of the narrowband signal is unaffected and it will show on the display well above the broadband signals. // Perhaps another piece of the puzzle falls into place? -Bob Sykes From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Bill Owsley Sent: Tuesday, December 06, 2011 5:23 PM To: Ken Javor; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Average detector/s Indeed it does. The measured signal in this particular case is broadband stuff of a modulated carrier. So far I can get a 20 dB spread when measuring the signal with all the different buttons and techniques available for average. And you know the limit falls right in the middle !! And the fingers start pointing... The instrument manual says the average detector finds the average of everything in each measuring window and reports that. instantaneous average ?!?! And then do a trace max hold on that, and it begins to look similar to peak. Now if I turn on averaging over time, for instance a running average of a 100 runs, The reported value settles down nicely. But, I suspect any interference has already happened. Or, If I slow the sweep time down, then the same settling occurs as each window is averaged during the measurement dwell and that number is reported. I have not found a reference to an averaging time. Is there one? From: Ken Javor ken.ja...@emccompliance.com To: EMC-PSTC@LISTSERV.IEEE.ORG Sent: Tuesday, December 6, 2011 4:43 PM Subject: Re: [PSES] Average detector/s If video averaging is done with a log amplifier instead of linear, then a geometric mean is taken rather than an arithmetic mean, the latter being an average detector. Both means naturally yield the same output with a cw input, but as the variation in the averaged quantities gets greater (standard deviation increases) the difference between the two types of means gets larger and larger. Hence, for an intermittent broadband signal of high amplitude but very low duty cycle and duration, one would expect very different outputs when using the log display vs. linear. Ken Javor Phone: (256) 650-5261 From: ralph.mcdiar...@schneider-electric.com Date: Tue, 6 Dec 2011 11:15:40 -0800 To: Bill Owsley wdows...@yahoo.com Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Average detector/s For in-house pre-compliance testing, we use a VBW of 10Hz to approximate the time response of an AVG detector. Seems to work quite well. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: Bill Owsley wdows...@yahoo.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 09:15 AM Subject: [PSES] Average detector/s Quasi-peak was fun, so now let's have fun with the Average detector/s, each and all of them ! For reference, EN 302 208-1, Sec. 8.3, 8.4, 8.5. Detection mode: Averaging Which averaging would this be? On the SA that I'm using, There is video averaging by reducing the VBW to something a lot smaller than RBW. There is EMI average detector, and There is average detector which has two modes, power and video. (one is the log of the average of power, the other is the average of the log of power.) And there is a multiple sweep averaging of the above. And there is adjusting the sweep time while averaging is turned on. And adjusting the span to be measured has an effect on the average measurement. Each can give a different result. So starting with the always correct answer in EMC, it depends, what are these dependencies? __ This email has been scanned by the Symantec Email Security.cloud service.
Re: [PSES] Average detector/s
I don¹t know what it is, but would expect the definition of the average detector, meaning the time constant, is in CISRR 16-1. Ken Javor Phone: (256) 650-5261 From: Bill Owsley wdows...@yahoo.com Reply-To: Bill Owsley wdows...@yahoo.com Date: Tue, 6 Dec 2011 14:23:20 -0800 (PST) To: Ken Javor ken.ja...@emccompliance.com, EMC-PSTC@LISTSERV.IEEE.ORG EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Average detector/s Indeed it does. The measured signal in this particular case is broadband stuff of a modulated carrier. So far I can get a 20 dB spread when measuring the signal with all the different buttons and techniques available for average. And you know the limit falls right in the middle !! And the fingers start pointing... The instrument manual says the average detector finds the average of everything in each measuring window and reports that. instantaneous average ?!?! And then do a trace max hold on that, and it begins to look similar to peak. Now if I turn on averaging over time, for instance a running average of a 100 runs, The reported value settles down nicely. But, I suspect any interference has already happened. Or, If I slow the sweep time down, then the same settling occurs as each window is averaged during the measurement dwell and that number is reported. I have not found a reference to an averaging time. Is there one? From: Ken Javor ken.ja...@emccompliance.com To: EMC-PSTC@LISTSERV.IEEE.ORG Sent: Tuesday, December 6, 2011 4:43 PM Subject: Re: [PSES] Average detector/s Re: [PSES] Average detector/s If video averaging is done with a log amplifier instead of linear, then a geometric mean is taken rather than an arithmetic mean, the latter being an average detector. Both means naturally yield the same output with a cw input, but as the variation in the averaged quantities gets greater (standard deviation increases) the difference between the two types of means gets larger and larger. Hence, for an intermittent broadband signal of high amplitude but very low duty cycle and duration, one would expect very different outputs when using the log display vs. linear. Ken Javor Phone: (256) 650-5261 From: ralph.mcdiar...@schneider-electric.com Date: Tue, 6 Dec 2011 11:15:40 -0800 To: Bill Owsley wdows...@yahoo.com Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Average detector/s For in-house pre-compliance testing, we use a VBW of 10Hz to approximate the time response of an AVG detector. Seems to work quite well. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: Bill Owsley wdows...@yahoo.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 09:15 AM Subject: [PSES] Average detector/s Quasi-peak was fun, so now let's have fun with the Average detector/s, each and all of them ! For reference, EN 302 208-1, Sec. 8.3, 8.4, 8.5. Detection mode: Averaging Which averaging would this be? On the SA that I'm using, There is video averaging by reducing the VBW to something a lot smaller than RBW. There is EMI average detector, and There is average detector which has two modes, power and video. (one is the log of the average of power, the other is the average of the log of power.) And there is a multiple sweep averaging of the above. And there is adjusting the sweep time while averaging is turned on. And adjusting the span to be measured has an effect on the average measurement. Each can give a different result. So starting with the always correct answer in EMC, it depends, what are these dependencies? __ 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 mailto:emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html 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/ http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net mailto:emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org mailto:mcantw...@ieee.org For policy questions, send
[PSES] NOM-121 approved labs
Opportunity to share: Regarding NOM-121, what labs are have been approved? I am looking for the names of labs that could do Wi-Fi product testing that is acceptable to COFETEL. Regards W. Richard Gartman, MS, CSP Product Stewardship Manager Texas Instruments, Education Technology 12500 TI Boulevard, Dallas, TX 75243 Office: 972-917-1636 Email: rgart...@ti.commailto:rgart...@ti.com www.education.ti.com/us/productstewardshiphttp://education.ti.com/us/productstewardship www.ti.com/ccrhttp://www.ti.com/ccr Please consider the environment before printing this email. There is only one earth - don't waste it.http://education.ti.com/us/productstewardship Car racing also prepares you for and expects you to live in the moment - perspective comes before and after the race. Preparation equals success.http://education.ti.com/us/productstewardship - 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
Re: [PSES] NOM-121 approved labs
HI Richard, UL CCS in Fremont, CA has an MRA in place with a Certification Body in Mexico. The MRA has been notified to COFETEL and our testing is accepted. Happy Holidays, Barbara __ Barbara L. Judge, Vice President UL CCS Manager, Strategic Planning and Development UL Verification Services, WiSE Business Sector TCB and CAB 47173 Benicia Street Fremont, CA 94538 Direct (510) 771-1104 Main: (510) 771-1000 Fax: (510) 661-0888 barbara.ju...@ccsemc.com BLOCKED::mailto:barbara.ju...@ccsemc.com - For more information about UL, its Marks, and its services for EMC, quality registrations and product certifications for global markets, please access our web sites at http://www.ul.com http://www.ul.com/ and http://www.ulc.ca http://www.ulc.ca/ or contact your local sales representative. -- * Internet E-mail Confidentiality Disclaimer ** This e-mail message may contain privileged or confidential information. If you are not the intended recipient, you may not disclose, use, disseminate, distribute, copy or rely upon this message or attachment in any way. If you received this e-mail message in error, please return by forwarding the message and its attachments to the sender. UL and its affiliates do not accept liability for any errors, omissions, corruption or virus in the contents of this message or any attachments. * From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Gartman, Richard Sent: Tuesday, December 06, 2011 3:08 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: NOM-121 approved labs Opportunity to share: Regarding NOM-121, what labs are have been approved? I am looking for the names of labs that could do Wi-Fi product testing that is acceptable to COFETEL. Regards W. Richard Gartman, MS, CSP Product Stewardship Manager Texas Instruments, Education Technology 12500 TI Boulevard, Dallas, TX 75243 Office: 972-917-1636 Email: rgart...@ti.com mailto:rgart...@ti.com www.education.ti.com/us/productstewardship http://education.ti.com/us/productstewardship www.ti.com/ccr http://www.ti.com/ccr Please consider the environment before printing this email. There is only one earth - don't waste it. http://education.ti.com/us/productstewardship Car racing also prepares you for and expects you to live in the moment - perspective comes before and after the race. Preparation equals success. http://education.ti.com/us/productstewardship - 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
Re: [PSES] Average detector/s
This is how CISPR16-1 writes about it: 6.4.1 Amplitude relationship Up to 1 000 MHz, the average detector is defined as follows: (linear average): the response of the measuring receiver to pulses of repetition rate nHz and impulse area of 1,4/n mVs at 50 ohm source impedance, shall be equal to the response of an unmodulated sine-wave signal at the tuned frequency having an rms value of 2 mV [66 dB(μV)]. A tolerance of 2,5 dB/–0,5 dB is permitted on the sine-wave voltage level. Note the fairly generous tolerance for the sinewave reference level. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: Ken Javor ken.ja...@emccompliance.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 02:56 PM Subject: Re: [PSES] Average detector/s I don’t know what it is, but would expect the definition of the average detector, meaning the time constant, is in CISRR 16-1. Ken Javor Phone: (256) 650-5261 From: Bill Owsley wdows...@yahoo.com Reply-To: Bill Owsley wdows...@yahoo.com Date: Tue, 6 Dec 2011 14:23:20 -0800 (PST) To: Ken Javor ken.ja...@emccompliance.com, EMC-PSTC@LISTSERV.IEEE.ORG EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Average detector/s Indeed it does. The measured signal in this particular case is broadband stuff of a modulated carrier. So far I can get a 20 dB spread when measuring the signal with all the different buttons and techniques available for average. And you know the limit falls right in the middle !! And the fingers start pointing... The instrument manual says the average detector finds the average of everything in each measuring window and reports that. instantaneous average ?!?! And then do a trace max hold on that, and it begins to look similar to peak. Now if I turn on averaging over time, for instance a running average of a 100 runs, The reported value settles down nicely. But, I suspect any interference has already happened. Or, If I slow the sweep time down, then the same settling occurs as each window is averaged during the measurement dwell and that number is reported. I have not found a reference to an averaging time. Is there one? From: Ken Javor ken.ja...@emccompliance.com To: EMC-PSTC@LISTSERV.IEEE.ORG Sent: Tuesday, December 6, 2011 4:43 PM Subject: Re: [PSES] Average detector/s Re: [PSES] Average detector/s If video averaging is done with a log amplifier instead of linear, then a geometric mean is taken rather than an arithmetic mean, the latter being an average detector. Both means naturally yield the same output with a cw input, but as the variation in the averaged quantities gets greater (standard deviation increases) the difference between the two types of means gets larger and larger. Hence, for an intermittent broadband signal of high amplitude but very low duty cycle and duration, one would expect very different outputs when using the log display vs. linear. Ken Javor Phone: (256) 650-5261 From: ralph.mcdiar...@schneider-electric.com Date: Tue, 6 Dec 2011 11:15:40 -0800 To: Bill Owsley wdows...@yahoo.com Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Average detector/s For in-house pre-compliance testing, we use a VBW of 10Hz to approximate the time response of an AVG detector. Seems to work quite well. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: Bill Owsley wdows...@yahoo.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 09:15 AM Subject: [PSES] Average detector/s Quasi-peak was fun, so now let's have fun with the Average detector/s, each and all of them ! For reference, EN 302 208-1, Sec. 8.3, 8.4, 8.5. Detection mode: Averaging Which averaging would this be? On the SA that I'm using, There is video averaging by reducing the VBW to something a lot smaller than RBW. There is EMI average detector, and There is average detector which has two modes, power and video. (one is the log of the average of power, the other is the average of the log of power.) And there is a multiple sweep averaging of the above. And there is adjusting the sweep time while averaging is turned on. And adjusting the span to be measured has an effect on the average measurement. Each can give a different result. So starting with the always correct answer in EMC, it depends, what are these dependencies? __ This email has been scanned by the Symantec Email Security.cloud service. __ - This message is from the IEEE Product Safety Engineering Society
Re: [PSES] Calibration practice for EMI test transducers
We might *like* measuring antennas to be low-Q, but remember the bicon shorting bars that were added some years ago? The skeleton bicons lacking them inserted a rather sharp notch that had to be accounted for in transducer tables. Baluns might go off from impact damage, too. And so on. I gave an ebay 50 MHz comb good past 2 GHz to a former employer who later gave all their own EMC lab gear to an NRTL. But you still have to check. For that matter, I've seen coax factors programmed with GAIN at a narrow range at microwave frequencies; that was caused by reflection from a crimped cable*. So we do need to be able to spot them. *This was due to the ignorance of operators collecting the data, IMO. I spoke to them and likely, they won't do it again. But they believed the SA/TG reading because they didn't know what they were measuring. That's another thread. Though the sweep may be continuous, if you can read amplitude only by marking pixels, you need to insure .5 BW or less per pixel. That's straight sampling theory, right? If your analyzer has a 1024 pixel wide screen you can't SEE less than about .1% of the scan width and can rely on less. Does it matter? Often it doesn't. Fun, isn't it? Cortland KA5S On 12/6/2011 5:11 PM, Ken Javor wrote: This discussion has gone far a field from the original post. I'm assuming some sort of scan has been run and a continuous sweep is available. The question is, how densely does that sweep need to be digitized? Not as a practical matter, but as a matter of compliance with standards or standard practice. What manner of antenna would have performance as cited below where at 100 MHz the antenna factor is 10 dB and at 120 MHz it is 12 dB, but at 110 MHz it could be 20 dB? Let's generalize the question to any closely spaced frequencies. Let's look at the types of antennas available. 30-200 MHz: A half-wave tuned dipole is nowhere near that sharp. Neither is a biconical. 200 -- 1000 MHz: A half-wave tuned dipole is nowhere near that sharp. Neither is a logperiodic, log-spiral, nor a Yagi. 1 GHz+: Logperiodic, log-spiral nor pyramidal horns act the way surmised. My conclusion, and the point here is to invite discussion, not close it out, is that no test-type antenna is a high Q device. Antennas can have arbitrarily high gains, depending on construction, but the high gain is a geometrical quality, not a high quality factor in the frequency domain. - 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
Re: [PSES] Calibration practice for EMI test transducers
In message cb03ef45.c9421%ken.ja...@emccompliance.com, dated Tue, 6 Dec 2011, Ken Javor ken.ja...@emccompliance.com writes: Antennas can have arbitrarily high gains, depending on construction, but the high gain is a geometrical quality, not a high quality factor in the frequency domain. True for electric antennas, I think, but not for magnetic. Tuned loops and ferrite-rod antennas can have high Q. CISPR 16 includes at least one magnetic antenna, although it may well not be high Q. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK Some people who are peeling the finch of the financial crisis are thinking of biting a rook. - 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
Re: [PSES] Average detector/s
The HP8568B we use here displays amplitude in 10dB increments, so I assume that means a log amplifier after the detector? (the amplifier driving the vert deflection responds to the logarithm of the signal level) _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: Ken Javor ken.ja...@emccompliance.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 01:45 PM Subject: Re: [PSES] Average detector/s If video averaging is done with a log amplifier instead of linear, then a geometric mean is taken rather than an arithmetic mean, the latter being an average detector. Both means naturally yield the same output with a cw input, but as the variation in the averaged quantities gets greater (standard deviation increases) the difference between the two types of means gets larger and larger. Hence, for an intermittent broadband signal of high amplitude but very low duty cycle and duration, one would expect very different outputs when using the log display vs. linear. Ken Javor Phone: (256) 650-5261 From: ralph.mcdiar...@schneider-electric.com Date: Tue, 6 Dec 2011 11:15:40 -0800 To: Bill Owsley wdows...@yahoo.com Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Average detector/s For in-house pre-compliance testing, we use a VBW of 10Hz to approximate the time response of an AVG detector. Seems to work quite well. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: Bill Owsley wdows...@yahoo.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 09:15 AM Subject: [PSES] Average detector/s Quasi-peak was fun, so now let's have fun with the Average detector/s, each and all of them ! For reference, EN 302 208-1, Sec. 8.3, 8.4, 8.5. Detection mode: Averaging Which averaging would this be? On the SA that I'm using, There is video averaging by reducing the VBW to something a lot smaller than RBW. There is EMI average detector, and There is average detector which has two modes, power and video. (one is the log of the average of power, the other is the average of the log of power.) And there is a multiple sweep averaging of the above. And there is adjusting the sweep time while averaging is turned on. And adjusting the span to be measured has an effect on the average measurement. Each can give a different result. So starting with the always correct answer in EMC, it depends, what are these dependencies? __ 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 mailto:emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html 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/ http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net mailto:emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org mailto:mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org mailto:j.bac...@ieee.org David Heald dhe...@gmail.com mailto: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,
Re: [PSES] Calibration practice for EMI test transducers
I sure hope that standard practice and practicality (pardon me) go hand-in-hand. If not, the committees members need to give their head a shake. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: Ken Javor ken.ja...@emccompliance.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 02:14 PM Subject: Re: [PSES] Calibration practice for EMI test transducers This discussion has gone far a field from the original post. I’m assuming some sort of scan has been run and a continuous sweep is available. The question is, how densely does that sweep need to be digitized? Not as a practical matter, but as a matter of compliance with standards or standard practice. What manner of antenna would have performance as cited below where at 100 MHz the antenna factor is 10 dB and at 120 MHz it is 12 dB, but at 110 MHz it could be 20 dB? Let’s generalize the question to any closely spaced frequencies. Let’s look at the types of antennas available. 30-200 MHz: A half-wave tuned dipole is nowhere near that sharp. Neither is a biconical. 200 – 1000 MHz: A half-wave tuned dipole is nowhere near that sharp. Neither is a logperiodic, log-spiral, nor a Yagi. 1 GHz+: Logperiodic, log-spiral nor pyramidal horns act the way surmised. My conclusion, and the point here is to invite discussion, not close it out, is that no test-type antenna is a high “Q” device. Antennas can have arbitrarily high gains, depending on construction, but the high gain is a geometrical quality, not a high quality factor in the frequency domain. Ken Javor Phone: (256) 650-5261 From: ralph.mcdiar...@schneider-electric.com Date: Tue, 6 Dec 2011 11:25:43 -0800 To: ce-test, qualified testing bv - Gert Gremmen g.grem...@cetest.nl Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Calibration practice for EMI test transducers 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 http://terpconnect.umd.edu/~petersd/interp.html or at http://www.ibiblio.org/e-notes/Splines/Lagrange.htm 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 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
Re: [PSES] NOM-121 approved labs
Richard, UL CCS, Cetecom and NTS (soon to be certified) - all three California labs Peter Merguerian pe...@goglobalcompliance.com (408) 931-3303 www.goglobalcompliance.com Sent from my iPhone On Dec 6, 2011, at 3:08 PM, Gartman, Richard rgart...@ti.com wrote: Opportunity to share: Regarding NOM-121, what labs are have been approved? I am looking for the names of labs that could do Wi-Fi product testing that is acceptable to COFETEL. Regards W. Richard Gartman, MS, CSP Product Stewardship Manager Texas Instruments, Education Technology 12500 TI Boulevard, Dallas, TX 75243 Office: 972-917-1636 Email: rgart...@ti.com www.education.ti.com/us/productstewardship www.ti.com/ccr Please consider the environment before printing this email. There is only one earth - don't waste it. Car racing also prepares you for and expects you to live in the moment – perspective comes before and after the race. Preparation equals success. - 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
