Re: [PSES] Average detector/s
For EMI each frequency need to be averaged discretely. That means that time per frequency needs to allow for the filter to settle. Several standards (not on hand) have translated that to sweep times. They can be very slow rates in the hour ranges. Same for QP. Regards, Ing. Gert Gremmen, BSc g.grem...@cetest.nl mailto:g.grem...@cetest.nl www.cetest.nl Kiotoweg 363 3047 BG Rotterdam T 31(0)104152426 F 31(0)104154953 Before printing, think about the environment. Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens Bill Owsley Verzonden: Tuesday, December 06, 2011 11:23 PM Aan: Ken Javor; EMC-PSTC@LISTSERV.IEEE.ORG Onderwerp: 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. __ - 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 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/ can be used for graphics (in well-used formats
Re: [PSES] Average detector/s
Bill This is a RTTE Directive article 3.2 radio spectrum standards not an EMC standard The standard details many parameters such as RBW, VBW, Span and Sweep time for a number of the tests. The Average detector is the a power average detector. Where test signal do not have a 100% duty cycle, the average measurement should (typically) be performed for the on time of the signal. Regards Charlie From: Bill Owsley [mailto:wdows...@yahoo.com] Sent: 06 December 2011 17:14 To: EMC-PSTC@LISTSERV.IEEE.ORG 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 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.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.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 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
Yes, the log amp is after the detector. The real question, though, is where the video filter used for averaging is placed in the circuitry. If I am not mistaken, it is placed after the log amp when using the log vertical display. To get correct averaging for measurement, you need to select linear vertical display mode. Note: The HP8568B can also display in vertical increments of 5 dB, 2 dB, and 1 dB. I grew up as an engineer on the HP8568. I worked for HP (and Agilent) for 26 years. The HP8568 appeared about a year after I got to HP. I got one of the first units. I worked with both the A and B versions for almost my whole career there. Donald Borowski Schweitzer Engineering Labs Pullman, WA, USA From: ralph.mcdiar...@schneider-electric.com To: Ken Javor ken.ja...@emccompliance.com Cc: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/06/2011 09:18 PM Subject:Re: [PSES] Average detector/s Sent by:emc-p...@ieee.org 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
[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] 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] 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 dhe
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] 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
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] 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
