Re: [PSES] Quasi-peak
In message 1322714376.48125.yahoomail...@web39604.mail.mud.yahoo.com, dated Wed, 30 Nov 2011, Bill Owsley wdows...@yahoo.com writes: Digital is a very narrow-band transmission and this spread spectrum, or FM signal seldom hits the receive freq That's a bit surprising. -- 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
Amund, A little work on Google(tm) finds many entries for the QP time constants. Here are URL's for two: Short form, a one page history by Ed Bronaugh: http://www.ieee.org/organizations/pubs/newsletters/emcs/summer01/pp.bronaugh.htm Time constants employed: http://www.scribd.com/doc/7118002/47/Detectors-time-constants (Fundamentals of Spectrum Analysis; Christoph Rauscher, Volker Janssen, and Roland Minihold) A spread spectrum clock places most of the clock energy outside the bandwidth of a measuring receiver, so it reads lower. Should a victim device have a wider bandwidth, it won't help the user! Cortland Richmond KA5S On 11/30/2011 2:11 PM, Amund Westin wrote: I tried to find some information on how the Quasi-Peak detetor works. How long time does it measure at each frequency, why does a spread spectrum clock solve emission problem, etc Anybody who knows where I can find it? B.r Amund - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
Hello Amund, Just to clarify one point, a spread spectrum clock is very different to a spread spectrum transmission scheme. Bluetooth is just one example of a spread spectrum transmission scheme where the modulated carrier ‘hops’ between frequency channels within a defined band. The receiver has to synchronously tune itself to the transmission frequency. Keeping with the Bluetooth example, simplistically there are 79 x 1MHz spaced bands between 2402 and 2480 MHz. During transmission, the carrier hops between these carrier frequencies, it connat stay at any one frequency for more than 400ms. Relevant to your question…. Spread spectrum clocks are used in digital systems to reduce emissions. It’s a little bit of a ‘cheat’ because the energy of the overall emissions is generally the same, but the narrowband levels measured by an averaging and/or integrating detectors (e.g. CISPR) are greatly reduced. Say you have a digital system clocking at 100MHz, you have potential narrowband emissions problems at 100MHz, harmonics thereof and any other frequencies divided down or synthesised up. If you ‘modulate’ your 100MHz clock by e.g. +/- 0.5% (99.5 – 100.5 MHz) you spread your emissions across a proportionate band. This band is generally much greater than the measurement bandwidth of measuring receivers. This is basically what happens to the emissions. | Narrowband Clock | || |- - - - - / \ - - - -- Limit |/ \ || | |/\ + | Spread Spectrum Clock | | |- - - - - - - - - -- Limit ||~~~| |/\ ||| + Hope this helps with spread spectrum clocks. - Original Message - From: Amund Westin Sent: 11/30/11 07:11 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Quasi-peak I tried to find some information on how the Quasi-Peak detetor works. How long time does it measure at each frequency, why does a spread spectrum clock solve emission problem, etc Anybody who knows where I can find it? B.r Amund - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org Da! vid 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] FCC Part 22/24/SAR testing
All Looking for a lab who can perform the following testing at short notice (location not important) * FCC Part 22: 850 MHz; GSM, GPRS, UMTS * FCC Part 24: 1900 MHz; GSM, GPRS, UMTS * FCC and EU SAR for quad band GSM/GPRS/UMTS Please contact me off line Regards Charlie Charlie Blackham Sulis Consultants Ltd Tel: +44 (0)7946 624317 Web: www.sulisconsultants.comhttp://www.sulisconsultants.com/ Registered in England and Wales, number 05466247 - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
Spread spectrum clocks work due to the measurement bandwidth of the receiver, so this effect holds for peak, quasi-peak, and average. Fundamentally, spread spectrum clocks do not solve emission problems. They just take the emitted energy and spread it over a wide bandwidth, wider than the measurement bandwidth, so that only a fraction of the energy falls within the measurement bandwidth. In effect, the measurement is fooled. In the real world, spread spectrum may or may not help reduce interference to communications systems. If the communications system is a fixed channel, narrow band system, then it may help. I say may because if the interference before spreading was in your desired channel, it will help. On the other hand, if you are using a near by channel, the interference without spreading would be rejected, but with spreading, some of the interference energy may now fall within your channel. Similarly for frequency hopping systems. Without spreading, the interference without spreading may make one channel unusable. With spreading, it will likely cause less severe problems on multiple channels. For non-hopping spread-spectrum communication systems (which are typically wide band), if all the interfering energy is contained within the channel, the fact that the interfering energy is spread or not makes no difference. Donald Borowski Schweitzer Engineering Labs Pullman, Washington, USA From: Jim Hulbert jim.hulb...@pb.com To: EMC-PSTC@LISTSERV.IEEE.ORG EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/01/2011 06:25 AM Subject:RE: [PSES] Quasi-peak Sent by:emc-p...@ieee.org It should be noted that quasi-peak is only specified up to 1 GHz. For emissions above 1 GHz, peak and average limits are defined and both must be met using peak and average detection receivers respectively. Don't think a spread spectrum clock helps much against a peak limit. Jim Hulbert From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Anthony Thomson Sent: Thursday, December 01, 2011 5:36 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak Hello Amund, Just to clarify one point, a spread spectrum clock is very different to a spread spectrum transmission scheme. Bluetooth is just one example of a spread spectrum transmission scheme where the modulated carrier ?hops? between frequency channels within a defined band. The receiver has to synchronously tune itself to the transmission frequency. Keeping with the Bluetooth example, simplistically there are 79 x 1MHz spaced bands between 2402 and 2480 MHz. During transmission, the carrier hops between these carrier frequencies, it connat stay at any one frequency for more than 400ms. Relevant to your question?. Spread spectrum clocks are used in digital systems to reduce emissions. It?s a little bit of a ?cheat? because the energy of the overall emissions is generally the same, but the narrowband levels measured by an averaging and/or integrating detectors (e.g. CISPR) are greatly reduced. Say you have a digital system clocking at 100MHz, you have potential narrowband emissions problems at 100MHz, harmonics thereof and any other frequencies divided down or synthesised up. If you ?modulate? your 100MHz clock by e.g. +/- 0.5% (99.5 ? 100.5 MHz) you spread your emissions across a proportionate band. This band is generally much greater than the measurement bandwidth of measuring receivers. This is basically what happens to the emissions. | Narrowband Clock | | | |- - - - - / \ - - - - - Limit | / \ | | | | / \ + | Spread Spectrum Clock | | |- - - - - - - - - - - Limit | |~~~| | / \ | | | + Hope this helps with spread spectrum clocks. - Original Message - From: Amund Westin Sent: 11/30/11 07:11 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Quasi-peak I tried to find some information on how the Quasi-Peak detetor works. How long time does it measure at each frequency, why does a spread spectrum clock solve emission problem, etc Anybody who knows where I can find it? B.r Amund - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:
Re: [PSES] Quasi-peak
Tony: I don’t want to appear to be overly picky, but your diagrams don’t show “what happens to the emissions,” but rather show how the QP detector receiver “sees” the emissions. In a dithered, or frequency hopping clock, the clock hops to a frequency, dwells there for a short moment and then hops to a new, relatively far away frequency. If your receiver happens to be sitting right at say, 100 MHz, and the clock hops to 100 MHz, the receiver only has a short time (before the clock hops again) to indicate the amplitude of the signal. A peak detector will quickly charge and show the signal level, but a QP detector has a slower time constant, so it can’t get up to the full signal amplitude before the clock hops away from the receiver’s “view.” The clock’s amplitude doesn’t change or spread or in any way decrease; all the dithered clock does is hop and jump all over a range of frequencies. Ed Price ed.pr...@cubic.com blocked::mailto:ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military Avionics EMC Is Our Specialty From: Anthony Thomson [mailto:ton...@europe.com] Sent: Thursday, December 01, 2011 2:36 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak Hello Amund, Just to clarify one point, a spread spectrum clock is very different to a spread spectrum transmission scheme. Bluetooth is just one example of a spread spectrum transmission scheme where the modulated carrier ‘hops’ between frequency channels within a defined band. The receiver has to synchronously tune itself to the transmission frequency. Keeping with the Bluetooth example, simplistically there are 79 x 1MHz spaced bands between 2402 and 2480 MHz. During transmission, the carrier hops between these carrier frequencies, it connat stay at any one frequency for more than 400ms. Relevant to your question…. Spread spectrum clocks are used in digital systems to reduce emissions. It’s a little bit of a ‘cheat’ because the energy of the overall emissions is generally the same, but the narrowband levels measured by an averaging and/or integrating detectors (e.g. CISPR) are greatly reduced. Say you have a digital system clocking at 100MHz, you have potential narrowband emissions problems at 100MHz, harmonics thereof and any other frequencies divided down or synthesised up. If you ‘modulate’ your 100MHz clock by e.g. +/- 0.5% (99.5 – 100.5 MHz) you spread your emissions across a proportionate band. This band is generally much greater than the measurement bandwidth of measuring receivers. This is basically what happens to the emissions. | Narrowband Clock | | | |- - - - - / \ - - - - - Limit | / \ | | | | / \ + | Spread Spectrum Clock | | |- - - - - - - - - - - Limit | |~~~| | / \ | | | + - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
Ed- Given your scenario, you are right. However, in my experience of measuring radiated emissions of spread spectrum clocks, I have always noticed a decrease in not only the quasi-peak and average measurements, but the peak measurement as well. I think this may be due to the bandwidth of the spreading signal -- if it is wider bandwidth than the receiver bandwidth (120 kHz CISPR in my case), then there will be reduction in the peak as well. With a high bandwidth spreading signal, the RF will not spend enough time within the bandwidth of the receiver for the receiver to respond to the full amplitude of the signal. Donald Borowski EMC Compliance Engineer Schweitzer Engineering Labs Pullman, WA, USA From: Price, Edward ed.pr...@cubic.com To: don_borow...@selinc.com, EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/01/2011 08:06 AM Subject:RE: [PSES] Quasi-peak Don: I think that the ?spread spectrum clock? works because of both the receiver bandwidth and the detector function. For instance, imagine a pure CW clock signal, and it is being hopped around in 1 kHz steps, all in the range of 10 kHz. Now imagine that a receiver with a 1 MHz resolution bandwidth is watching that signal. The indicated amplitude will be the same with Peak, QP Average detectors. Because the hopping is always within the receiver bandwidth, the hopping has no effect. As the hopping stays within the receiver BW, each detector has plenty of time to reach the full amplitude of the signal. Now imagine that a hop starts well outside the RBW; the receiver sees nothing. Then the clock hops into the RBW, and each detector starts charging. Fifty microseconds later, the clock hops out of the RBW. You look at the three detectors, and the Peak reads, say 1.0. The QP might read 0.1, and the Average might read 0.0. The difference was all about how long the receiver had to observe the signal; all detectors ?saw? the same amplitude signal, but they could only report what their time constants allowed. Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military Avionics EMC Is Our Specialty -Original Message- From: don_borow...@selinc.com [mailto:don_borow...@selinc.com] Sent: Thursday, December 01, 2011 7:22 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak Spread spectrum clocks work due to the measurement bandwidth of the receiver, so this effect holds for peak, quasi-peak, and average. Donald Borowski Schweitzer Engineering Labs Pullman, Washington, USA - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
Don: I think that the spread spectrum clock works because of both the receiver bandwidth and the detector function. For instance, imagine a pure CW clock signal, and it is being hopped around in 1 kHz steps, all in the range of 10 kHz. Now imagine that a receiver with a 1 MHz resolution bandwidth is watching that signal. The indicated amplitude will be the same with Peak, QP Average detectors. Because the hopping is always within the receiver bandwidth, the hopping has no effect. As the hopping stays within the receiver BW, each detector has plenty of time to reach the full amplitude of the signal. Now imagine that a hop starts well outside the RBW; the receiver sees nothing. Then the clock hops into the RBW, and each detector starts charging. Fifty microseconds later, the clock hops out of the RBW. You look at the three detectors, and the Peak reads, say 1.0. The QP might read 0.1, and the Average might read 0.0. The difference was all about how long the receiver had to observe the signal; all detectors saw the same amplitude signal, but they could only report what their time constants allowed. Ed Price ed.pr...@cubic.com blocked::mailto:ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military Avionics EMC Is Our Specialty -Original Message- From: don_borow...@selinc.com [mailto:don_borow...@selinc.com] Sent: Thursday, December 01, 2011 7:22 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak Spread spectrum clocks work due to the measurement bandwidth of the receiver, so this effect holds for peak, quasi-peak, and average. Donald Borowski Schweitzer Engineering Labs Pullman, Washington, USA - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
Good stuff, this empirical experience. But the question remains - does this spread-spectrum stuff, for a comparative power level, increase or decrease interference with my master-blaster 5000 remote toilet controller? One member said that it only will affect stuff that is very close to the operating freq and that the most digital receivers would not see it. But EMC amateurs such as me need MOAR empirical experience from Don and Ed and et al. For my employer's products, I am more concerned about customer complaints than demonstrated margin from some fantastical limit line in an EMC standard. Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of don_borow...@selinc.com Sent: Thursday, December 01, 2011 8:58 AM To: Price, Edward Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Quasi-peak Ed- Given your scenario, you are right. However, in my experience of measuring radiated emissions of spread spectrum clocks, I have always noticed a decrease in not only the quasi-peak and average measurements, but the peak measurement as well. I think this may be due to the bandwidth of the spreading signal -- if it is wider bandwidth than the receiver bandwidth (120 kHz CISPR in my case), then there will be reduction in the peak as well. With a high bandwidth spreading signal, the RF will not spend enough time within the bandwidth of the receiver for the receiver to respond to the full amplitude of the signal. Donald Borowski EMC Compliance Engineer Schweitzer Engineering Labs Pullman, WA, USA From: Price, Edward ed.pr...@cubic.com To: don_borow...@selinc.com, EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/01/2011 08:06 AM Subject:RE: [PSES] Quasi-peak Don: I think that the ?spread spectrum clock? works because of both the receiver bandwidth and the detector function. For instance, imagine a pure CW clock signal, and it is being hopped around in 1 kHz steps, all in the range of 10 kHz. Now imagine that a receiver with a 1 MHz resolution bandwidth is watching that signal. The indicated amplitude will be the same with Peak, QP Average detectors. Because the hopping is always within the receiver bandwidth, the hopping has no effect. As the hopping stays within the receiver BW, each detector has plenty of time to reach the full amplitude of the signal. Now imagine that a hop starts well outside the RBW; the receiver sees nothing. Then the clock hops into the RBW, and each detector starts charging. Fifty microseconds later, the clock hops out of the RBW. You look at the three detectors, and the Peak reads, say 1.0. The QP might read 0.1, and the Average might read 0.0. The difference was all about how long the receiver had to observe the signal; all detectors ?saw? the same amplitude signal, but they could only report what their time constants allowed. Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military Avionics EMC Is Our Specialty -Original Message- From: don_borow...@selinc.com [mailto:don_borow...@selinc.com] Sent: Thursday, December 01, 2011 7:22 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak Spread spectrum clocks work due to the measurement bandwidth of the receiver, so this effect holds for peak, quasi-peak, and average. Donald Borowski Schweitzer Engineering Labs Pullman, Washington, USA - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
The QP detector has 2 tasks: 1. Mimic the response of a standard AM receiver IF band filter (4 kHz or so) to short impulses (1 mS) (while the meas rec. uses a 120 kHz filter) 2. Hold the response to increase the measurement result when short pulses repeat Gert Gremmen Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens Price, Edward Verzonden: donderdag 1 december 2011 16:45 Aan: Anthony Thomson; EMC-PSTC@LISTSERV.IEEE.ORG Onderwerp: RE: [PSES] Quasi-peak Tony: I don’t want to appear to be overly picky, but your diagrams don’t show “what happens to the emissions,” but rather show how the QP detector receiver “sees” the emissions. In a dithered, or frequency hopping clock, the clock hops to a frequency, dwells there for a short moment and then hops to a new, relatively far away frequency. If your receiver happens to be sitting right at say, 100 MHz, and the clock hops to 100 MHz, the receiver only has a short time (before the clock hops again) to indicate the amplitude of the signal. A peak detector will quickly charge and show the signal level, but a QP detector has a slower time constant, so it can’t get up to the full signal amplitude before the clock hops away from the receiver’s “view.” The clock’s amplitude doesn’t change or spread or in any way decrease; all the dithered clock does is hop and jump all over a range of frequencies. Ed Price ed.pr...@cubic.com blocked::mailto:ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military Avionics EMC Is Our Specialty From: Anthony Thomson [mailto:ton...@europe.com] Sent: Thursday, December 01, 2011 2:36 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak Hello Amund, Just to clarify one point, a spread spectrum clock is very different to a spread spectrum transmission scheme. Bluetooth is just one example of a spread spectrum transmission scheme where the modulated carrier ‘hops’ between frequency channels within a defined band. The receiver has to synchronously tune itself to the transmission frequency. Keeping with the Bluetooth example, simplistically there are 79 x 1MHz spaced bands between 2402 and 2480 MHz. During transmission, the carrier hops between these carrier frequencies, it connat stay at any one frequency for more than 400ms. Relevant to your question…. Spread spectrum clocks are used in digital systems to reduce emissions. It’s a little bit of a ‘cheat’ because the energy of the overall emissions is generally the same, but the narrowband levels measured by an averaging and/or integrating detectors (e.g. CISPR) are greatly reduced. Say you have a digital system clocking at 100MHz, you have potential narrowband emissions problems at 100MHz, harmonics thereof and any other frequencies divided down or synthesised up. If you ‘modulate’ your 100MHz clock by e.g. +/- 0.5% (99.5 – 100.5 MHz) you spread your emissions across a proportionate band. This band is generally much greater than the measurement bandwidth of measuring receivers. This is basically what happens to the emissions. | Narrowband Clock | | | |- - - - - / \ - - - - - Limit | / \ | | | | / \ + | Spread Spectrum Clock | | |- - - - - - - - - - - Limit | |~~~| | / \ | | | + - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell
Re: [PSES] Quasi-peak
We used this technique in house for awhile before it went public. http://glendash.com/Dash_of_EMC/Shiver_Me_Timers/Shiver_Me_Timers.htm And had it reviewed by the FCC since the peak levels hardly moved but the QP could be induced to move down a lot. The original QP was based on a needle meter swinging coil thingy from the Simpson days and the human perceived annoyance factor during reception. The term spread spectrum was used describe what happened to the spectrum on an analyzer. Conveniently, the competition took it to mean frequency hopping, and tried to implement that, and found a lot of new problems. Communications frequency hops. SSCG does a smooth frequency variation within the intended parameters. The so-called jitter was calculated in femto-seconds, smaller than any of the other tolerances. so for the master-blaster digital receive, When the planets and stars align and if it misses a bit during reception and the transmitter does not push the button again, yes the toilet won't flush. Turn on error detection and correction and try again. Don't use it, just get a better EMC design. - Bill From: Brian Oconnell oconne...@tamuracorp.com To: EMC-PSTC@LISTSERV.IEEE.ORG Sent: Thursday, December 1, 2011 12:22 PM Subject: RE: [PSES] Quasi-peak Good stuff, this empirical experience. But the question remains - does this spread-spectrum stuff, for a comparative power level, increase or decrease interference with my master-blaster 5000 remote toilet controller? One member said that it only will affect stuff that is very close to the operating freq and that the most digital receivers would not see it. But EMC amateurs such as me need MOAR empirical experience from Don and Ed and et al. For my employer's products, I am more concerned about customer complaints than demonstrated margin from some fantastical limit line in an EMC standard. Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of don_borow...@selinc.com Sent: Thursday, December 01, 2011 8:58 AM To: Price, Edward Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Quasi-peak Ed- Given your scenario, you are right. However, in my experience of measuring radiated emissions of spread spectrum clocks, I have always noticed a decrease in not only the quasi-peak and average measurements, but the peak measurement as well. I think this may be due to the bandwidth of the spreading signal -- if it is wider bandwidth than the receiver bandwidth (120 kHz CISPR in my case), then there will be reduction in the peak as well. With a high bandwidth spreading signal, the RF will not spend enough time within the bandwidth of the receiver for the receiver to respond to the full amplitude of the signal. Donald Borowski EMC Compliance Engineer Schweitzer Engineering Labs Pullman, WA, USA From: Price, Edward ed.pr...@cubic.com To: don_borow...@selinc.com, EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/01/2011 08:06 AM Subject: RE: [PSES] Quasi-peak Don: I think that the ?spread spectrum clock? works because of both the receiver bandwidth and the detector function. For instance, imagine a pure CW clock signal, and it is being hopped around in 1 kHz steps, all in the range of 10 kHz. Now imagine that a receiver with a 1 MHz resolution bandwidth is watching that signal. The indicated amplitude will be the same with Peak, QP Average detectors. Because the hopping is always within the receiver bandwidth, the hopping has no effect. As the hopping stays within the receiver BW, each detector has plenty of time to reach the full amplitude of the signal. Now imagine that a hop starts well outside the RBW; the receiver sees nothing. Then the clock hops into the RBW, and each detector starts charging. Fifty microseconds later, the clock hops out of the RBW. You look at the three detectors, and the Peak reads, say 1.0. The QP might read 0.1, and the Average might read 0.0. The difference was all about how long the receiver had to observe the signal; all detectors ?saw? the same amplitude signal, but they could only report what their time constants allowed. Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military Avionics EMC Is Our Specialty -Original Message- From: don_borow...@selinc.com [mailto:don_borow...@selinc.com] Sent: Thursday, December 01, 2011 7:22 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak Spread spectrum clocks work due to the measurement bandwidth of the receiver, so this effect holds for peak, quasi-peak, and average. Donald Borowski Schweitzer Engineering Labs Pullman, Washington, USA - 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
Re: [PSES] Quasi-peak
Brian- I think the answer is (as it is in so many cases): it depends. Look at my reply to Jim Hulbert for some examples of how 'it depends'. As far as digital receivers, they will see interference from both CW and spread spectrum clocks. But the effects can be anything from negligible to stopping communications. For direct-sequence spread spectrum systems (e.g., CDMA cell phones), interference from either type of clock will be the same, assuming the total power is the same and the interfering signal is fully contained within the bandwidth of the receiver. An interesting example is CDMA, where the base station controls the power level of all the cell phones it is talking with so that at the base station all the cell phone signals it receives run at a standard bit error rate, about 1 in 100. If some interference comes along in the channel that increases the bit error rate, the base station will command the cell phones to increase power to get the bit error rate back down to about 1 in 100. (BTW, CDMA can run up to 30 cell phones in the same channel, with all the phones are transmitting continuously on the same frequency. The system is able to sort them all out, but that is another lengthy conversation). So the effect of any given spread-spectrum clock on any given remote toilet controller radio depends on the characteristics of both the spread-spectrum clock and the radio system. There ain't no easy answers to it all. All that is for sure is that spread-spectrum 'fools' the emissions measurement, which is looking for a certain amount of power (average or quasi-peak) within a given bandwidth, rather than total emitted power. The standards committees are well aware of what is going on and have been dancing around the issue for decades. I think there is movement towards looking at total emitted power, especially as EMC receivers progress to using wide total bandwidth FFT-based measurements. Donald Borowski EMC Compliance Engineer Schweitzer Engineering Labs Pullman, WA, USA From: Brian Oconnell oconne...@tamuracorp.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/01/2011 09:25 AM Subject:RE: [PSES] Quasi-peak Sent by:emc-p...@ieee.org Good stuff, this empirical experience. But the question remains - does this spread-spectrum stuff, for a comparative power level, increase or decrease interference with my master-blaster 5000 remote toilet controller? One member said that it only will affect stuff that is very close to the operating freq and that the most digital receivers would not see it. But EMC amateurs such as me need MOAR empirical experience from Don and Ed and et al. For my employer's products, I am more concerned about customer complaints than demonstrated margin from some fantastical limit line in an EMC standard. Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of don_borow...@selinc.com Sent: Thursday, December 01, 2011 8:58 AM To: Price, Edward Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Quasi-peak Ed- Given your scenario, you are right. However, in my experience of measuring radiated emissions of spread spectrum clocks, I have always noticed a decrease in not only the quasi-peak and average measurements, but the peak measurement as well. I think this may be due to the bandwidth of the spreading signal -- if it is wider bandwidth than the receiver bandwidth (120 kHz CISPR in my case), then there will be reduction in the peak as well. With a high bandwidth spreading signal, the RF will not spend enough time within the bandwidth of the receiver for the receiver to respond to the full amplitude of the signal. Donald Borowski EMC Compliance Engineer Schweitzer Engineering Labs Pullman, WA, USA From: Price, Edward ed.pr...@cubic.com To: don_borow...@selinc.com, EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/01/2011 08:06 AM Subject:RE: [PSES] Quasi-peak Don: I think that the ?spread spectrum clock? works because of both the receiver bandwidth and the detector function. For instance, imagine a pure CW clock signal, and it is being hopped around in 1 kHz steps, all in the range of 10 kHz. Now imagine that a receiver with a 1 MHz resolution bandwidth is watching that signal. The indicated amplitude will be the same with Peak, QP Average detectors. Because the hopping is always within the receiver bandwidth, the hopping has no effect. As the hopping stays within the receiver BW, each detector has plenty of time to reach the full amplitude of the signal. Now imagine that a hop starts well outside the RBW; the receiver sees nothing. Then the clock hops into the RBW, and each detector starts charging. Fifty microseconds later, the clock hops out of the RBW. You look at the three detectors, and the Peak reads, say 1.0. The QP might read 0.1, and the Average might read 0.0. The difference was all about how long the receiver had to observe the signal; all detectors ?saw? the same amplitude
Re: [PSES] Quasi-peak
In message 2b83256001484461b5f6adf4c41df...@tamuracorp.com, dated Thu, 1 Dec 2011, Brian Oconnell oconne...@tamuracorp.com writes: But the question remains - does this spread-spectrum stuff, for a comparative power level, increase or decrease interference with my master-blaster 5000 remote toilet controller? As is very common with such EMC questions, the answer is a definite 'maybe'. Closely define the environment, separation and the immunity characteristics of your robot loo and you may get a slightly more definite 'maybe'. -- 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
Richard Schultz (of ANSI C63) always told me there were 3 answer to any EMC question asking about 'if' it will affect something? YES NO MAYBE I'd guess Mr. Schultz knew enough to say that! Michael Sundstrom OHD / TREQ Dallas Electronic Lab Analyst, EMC Lead 2170 French Settlement Rd, Suite B Dallas, Texas 75212 (214) 579 6312 (940) 390 3644c KB5UKT Albert Einstein once said, The definition of insanity is doing the same thing over and over again and expecting different results. -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Thursday, December 01, 2011 12:22 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak In message 2b83256001484461b5f6adf4c41df...@tamuracorp.com, dated Thu, 1 Dec 2011, Brian Oconnell oconne...@tamuracorp.com writes: But the question remains - does this spread-spectrum stuff, for a comparative power level, increase or decrease interference with my master-blaster 5000 remote toilet controller? As is very common with such EMC questions, the answer is a definite 'maybe'. Closely define the environment, separation and the immunity characteristics of your robot loo and you may get a slightly more definite 'maybe'. -- 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
Todd Hubing would add one more - It depends. Ghery S. Pettit -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Sundstrom, Michael Sent: Thursday, December 01, 2011 10:56 AM To: John Woodgate; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Quasi-peak Richard Schultz (of ANSI C63) always told me there were 3 answer to any EMC question asking about 'if' it will affect something? YES NO MAYBE I'd guess Mr. Schultz knew enough to say that! Michael Sundstrom OHD / TREQ Dallas Electronic Lab Analyst, EMC Lead 2170 French Settlement Rd, Suite B Dallas, Texas 75212 (214) 579 6312 (940) 390 3644c KB5UKT Albert Einstein once said, The definition of insanity is doing the same thing over and over again and expecting different results. -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Thursday, December 01, 2011 12:22 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak In message 2b83256001484461b5f6adf4c41df...@tamuracorp.com, dated Thu, 1 Dec 2011, Brian Oconnell oconne...@tamuracorp.com writes: But the question remains - does this spread-spectrum stuff, for a comparative power level, increase or decrease interference with my master-blaster 5000 remote toilet controller? As is very common with such EMC questions, the answer is a definite 'maybe'. Closely define the environment, separation and the immunity characteristics of your robot loo and you may get a slightly more definite 'maybe'. -- 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
Well, he might, maybe not -Original Message- From: Pettit, Ghery [mailto:ghery.pet...@intel.com] Sent: Thursday, December 01, 2011 11:19 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak Todd Hubing would add one more - It depends. Ghery S. Pettit -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Sundstrom, Michael Sent: Thursday, December 01, 2011 10:56 AM To: John Woodgate; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Quasi-peak Richard Schultz (of ANSI C63) always told me there were 3 answer to any EMC question asking about 'if' it will affect something? YES NO MAYBE I'd guess Mr. Schultz knew enough to say that! Michael Sundstrom OHD / TREQ Dallas Electronic Lab Analyst, EMC Lead 2170 French Settlement Rd, Suite B Dallas, Texas 75212 (214) 579 6312 (940) 390 3644c KB5UKT Albert Einstein once said, The definition of insanity is doing the same thing over and over again and expecting different results. -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Thursday, December 01, 2011 12:22 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak In message 2b83256001484461b5f6adf4c41df...@tamuracorp.com, dated Thu, 1 Dec 2011, Brian Oconnell oconne...@tamuracorp.com writes: But the question remains - does this spread-spectrum stuff, for a comparative power level, increase or decrease interference with my master-blaster 5000 remote toilet controller? As is very common with such EMC questions, the answer is a definite 'maybe'. Closely define the environment, separation and the immunity characteristics of your robot loo and you may get a slightly more definite 'maybe'. -- 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For
Re: [PSES] Quasi-peak
In message 1abb0f6ff6cb7545adad042f566d5f4449101...@sv-mailbox01.ohdc.com, dated Thu, 1 Dec 2011, Sundstrom, Michael michael_sundst...@overheaddoor.com writes: Richard Schultz (of ANSI C63) always told me there were 3 answer to any EMC question asking about 'if' it will affect something? YES NO MAYBE But Albert clearly never did any EMC testing: Albert Einstein once said, The definition of insanity is doing the same thing over and over again and expecting different results. We are all insane. QED! -- 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
But Albert was a Theoretician, not an Experimentalist. Doing the same thing over over may be boring, but every so often, something truly weird does happen, and these are the moments that illuminate (or incinerate). Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military Avionics EMC Is Our Specialty -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Thursday, December 01, 2011 11:15 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak In message 1abb0f6ff6cb7545adad042f566d5f4449101...@sv-mailbox01.ohdc.com, dated Thu, 1 Dec 2011, Sundstrom, Michael michael_sundst...@overheaddoor.com writes: Richard Schultz (of ANSI C63) always told me there were 3 answer to any EMC question asking about 'if' it will affect something? YES NO MAYBE But Albert clearly never did any EMC testing: Albert Einstein once said, The definition of insanity is doing the same thing over and over again and expecting different results. We are all insane. QED! -- 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
Brian: Wow, you want a practical answer!! Well, in my experience of doing susceptibility on a lot of military systems (where the comm links are almost always encrypted digital bit streams), I find that the default 1 kHz 50% duty cycle (square wave) is a good choice for modulation. One of our data links might be running in Ku-band, with a 20 MB stream. We might have frames of data that are a millisecond long, with each frame consisting of words which are in turn composed of bits. The time slot of each bit is used as a place-holder for either a 1 or a ) logic bit. If we have a word that is supposed to be say 100111110, and we drop our test signal onto this bit stream, the link receiver might see 1. This is not what was sent, and would cause an error to be declared for the word. If there is no provision for error correction or redundancy, then this bad data could do most anything, from causing one tiny anomaly to crashing the whole system. All you have to do is drop some energy at the moment that 0's are happening, and the receiver reads them as 1's. When you manage to create interference, the threshold is very sharp. The digital channel doesn't degrade gracefully, but rather collapses precipitously. Ed Price ed.pr...@cubic.com blocked::mailto:ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military Avionics EMC Is Our Specialty -Original Message- From: Brian Oconnell [mailto:oconne...@tamuracorp.com] Sent: Thursday, December 01, 2011 9:22 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak Good stuff, this empirical experience. But the question remains - does this spread-spectrum stuff, for a comparative power level, increase or decrease interference with my master-blaster 5000 remote toilet controller? One member said that it only will affect stuff that is very close to the operating freq and that the most digital receivers would not see it. But EMC amateurs such as me need MOAR empirical experience from Don and Ed and et al. For my employer's products, I am more concerned about customer complaints than demonstrated margin from some fantastical limit line in an EMC standard. Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of don_borow...@selinc.com Sent: Thursday, December 01, 2011 8:58 AM To: Price, Edward Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Quasi-peak Ed- Given your scenario, you are right. However, in my experience of measuring radiated emissions of spread spectrum clocks, I have always noticed a decrease in not only the quasi-peak and average measurements, but the peak measurement as well. I think this may be due to the bandwidth of the spreading signal -- if it is wider bandwidth than the receiver bandwidth (120 kHz CISPR in my case), then there will be reduction in the peak as well. With a high bandwidth spreading signal, the RF will not spend enough time within the bandwidth of the receiver for the receiver to respond to the full amplitude of the signal. Donald Borowski EMC Compliance Engineer Schweitzer Engineering Labs Pullman, WA, USA From: Price, Edward ed.pr...@cubic.com To: don_borow...@selinc.com, EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/01/2011 08:06 AM Subject:RE: [PSES] Quasi-peak Don: I think that the ?spread spectrum clock? works because of both the receiver bandwidth and the detector function. For instance, imagine a pure CW clock signal, and it is being hopped around in 1 kHz steps, all in the range of 10 kHz. Now imagine that a receiver with a 1 MHz resolution bandwidth is watching that signal. The indicated amplitude will be the same with Peak, QP Average detectors. Because the hopping is always within the receiver bandwidth, the hopping has no effect. As the hopping stays within the receiver BW, each detector has plenty of time to reach the full amplitude of the signal. Now imagine that a hop starts well outside the RBW; the receiver sees nothing. Then the clock hops into the RBW, and each detector starts charging. Fifty microseconds later, the clock hops out of the RBW. You look at the three detectors, and the Peak reads, say 1.0. The QP might read 0.1, and the Average might read 0.0. The difference was all about how long the receiver had to observe the signal; all detectors ?saw? the same amplitude signal, but they could only report what their time constants allowed. Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military Avionics EMC Is Our Specialty -Original Message- From: don_borow...@selinc.com [mailto:don_borow...@selinc.com]
Re: [PSES] Quasi-peak
Gracefully degradation is a term often associated with software systems. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: Price, Edward ed.pr...@cubic.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/01/2011 12:00 PM Subject: Re: [PSES] Quasi-peak Brian: Wow, you want a practical answer!! Well, in my experience of doing susceptibility on a lot of military systems (where the comm links are almost always encrypted digital bit streams), I find that the default 1 kHz 50% duty cycle (square wave) is a good choice for modulation. One of our data links might be running in Ku-band, with a 20 MB stream. We might have frames of data that are a millisecond long, with each frame consisting of words which are in turn composed of bits. The time slot of each bit is used as a “place-holder” for either a 1 or a ) logic bit. If we have a word that is supposed to be say 100111110, and we drop our test signal onto this bit stream, the link receiver might see 1. This is not what was sent, and would cause an error to be declared for the word. If there is no provision for error correction or redundancy, then this bad data could do most anything, from causing one tiny anomaly to crashing the whole system. All you have to do is drop some energy at the moment that 0’s are happening, and the receiver reads them as 1’s. When you manage to create interference, the threshold is very sharp. The digital channel doesn’t degrade gracefully, but rather collapses precipitously. Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military Avionics EMC Is Our Specialty -Original Message- From: Brian Oconnell [mailto:oconne...@tamuracorp.com] Sent: Thursday, December 01, 2011 9:22 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak Good stuff, this empirical experience. But the question remains - does this spread-spectrum stuff, for a comparative power level, increase or decrease interference with my master-blaster 5000 remote toilet controller? One member said that it only will affect stuff that is very close to the operating freq and that the most digital receivers would not see it. But EMC amateurs such as me need MOAR empirical experience from Don and Ed and et al. For my employer's products, I am more concerned about customer complaints than demonstrated margin from some fantastical limit line in an EMC standard. Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of don_borow...@selinc.com Sent: Thursday, December 01, 2011 8:58 AM To: Price, Edward Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Quasi-peak Ed- Given your scenario, you are right. However, in my experience of measuring radiated emissions of spread spectrum clocks, I have always noticed a decrease in not only the quasi-peak and average measurements, but the peak measurement as well. I think this may be due to the bandwidth of the spreading signal -- if it is wider bandwidth than the receiver bandwidth (120 kHz CISPR in my case), then there will be reduction in the peak as well. With a high bandwidth spreading signal, the RF will not spend enough time within the bandwidth of the receiver for the receiver to respond to the full amplitude of the signal. Donald Borowski EMC Compliance Engineer Schweitzer Engineering Labs Pullman, WA, USA From: Price, Edward ed.pr...@cubic.com To: don_borow...@selinc.com, EMC-PSTC@LISTSERV.IEEE.ORG Date: 12/01/2011 08:06 AM Subject:RE: [PSES] Quasi-peak Don: I think that the ?spread spectrum clock? works because of both the receiver bandwidth and the detector function. For instance, imagine a pure CW clock signal, and it is being hopped around in 1 kHz steps, all in the range of 10 kHz. Now imagine that a receiver with a 1 MHz resolution bandwidth is watching that signal. The indicated amplitude will be the same with Peak, QP Average detectors. Because the hopping is always within the receiver bandwidth, the hopping has no effect. As the hopping stays within the receiver BW, each detector has plenty of time to reach the full amplitude of the signal. Now imagine that a hop starts well outside the RBW; the receiver sees nothing. Then the clock hops into the RBW, and each detector starts charging. Fifty microseconds later, the clock hops out of the RBW. You look at the three detectors, and the Peak reads, say 1.0. The QP might read 0.1, and the Average might read 0.0. The difference was all about how long the receiver had to observe the signal; all detectors ?saw? the same amplitude signal, but they could only report what their time constants
Re: [PSES] Quasi-peak
And by response do you mean the time-constant used in a typical AM receiver AVC? . _ 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: 12/01/2011 09:58 AM Subject: Re: [PSES] Quasi-peak The QP detector has 2 tasks: 1. Mimic the response of a standard AM receiver IF band filter (4 kHz or so) to short impulses (1 mS) (while the meas rec. uses a 120 kHz filter) 2. Hold the response to increase the measurement result when short pulses repeat Gert Gremmen Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens Price, Edward Verzonden: donderdag 1 december 2011 16:45 Aan: Anthony Thomson; EMC-PSTC@LISTSERV.IEEE.ORG Onderwerp: RE: [PSES] Quasi-peak Tony: I don’t want to appear to be overly picky, but your diagrams don’t show “what happens to the emissions,” but rather show how the QP detector receiver “sees” the emissions. In a dithered, or frequency hopping clock, the clock hops to a frequency, dwells there for a short moment and then hops to a new, relatively far away frequency. If your receiver happens to be sitting right at say, 100 MHz, and the clock hops to 100 MHz, the receiver only has a short time (before the clock hops again) to indicate the amplitude of the signal. A peak detector will quickly charge and show the signal level, but a QP detector has a slower time constant, so it can’t get up to the full signal amplitude before the clock hops away from the receiver’s “view.” The clock’s amplitude doesn’t change or spread or in any way decrease; all the dithered clock does is hop and jump all over a range of frequencies. Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military Avionics EMC Is Our Specialty From: Anthony Thomson [mailto:ton...@europe.com] Sent: Thursday, December 01, 2011 2:36 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak Hello Amund, Just to clarify one point, a spread spectrum clock is very different to a spread spectrum transmission scheme. Bluetooth is just one example of a spread spectrum transmission scheme where the modulated carrier ‘hops’ between frequency channels within a defined band. The receiver has to synchronously tune itself to the transmission frequency. Keeping with the Bluetooth example, simplistically there are 79 x 1MHz spaced bands between 2402 and 2480 MHz. During transmission, the carrier hops between these carrier frequencies, it connat stay at any one frequency for more than 400ms. Relevant to your question…. Spread spectrum clocks are used in digital systems to reduce emissions. It’s a little bit of a ‘cheat’ because the energy of the overall emissions is generally the same, but the narrowband levels measured by an averaging and/or integrating detectors (e.g. CISPR) are greatly reduced. Say you have a digital system clocking at 100MHz, you have potential narrowband emissions problems at 100MHz, harmonics thereof and any other frequencies divided down or synthesised up. If you ‘modulate’ your 100MHz clock by e.g. +/- 0.5% (99.5 – 100.5 MHz) you spread your emissions across a proportionate band. This band is generally much greater than the measurement bandwidth of measuring receivers. This is basically what happens to the emissions. | Narrowband Clock | | | |- - - - - / \ - - - - - Limit | / \ | | | | / \ + | Spread Spectrum Clock | | |- - - - - - - - - - - Limit | |~~~| | / \ | | | + - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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
[PSES] compliance dogs
None of this happened at my place of employment. But it did happen somewhere. Rated PG-13. Manager - bad! very bad compliance dog! Compliance Engineer - woof? M - sit compliance guy, sit CE - grrr M - down boy, I said sit CE - w M - now roll over and put your paw on the report CE - grrr M - down boy, I said release to production Ce - groll M - ok then, off the furniture and out to the back yard CE - whimperrr M - tell HR to go to the pound and find another dog CE - holoaoohhooo M - and have HR shut up that compliance dog before the neighbors complain HR - meow M - there you are - and clean up the big pile of doo-doo on the lab floor HR - hss M - shut up and get these doggie obedience problems fixed HR - meh ROORWR HSS M - geez these cats are worse than the dogs. will have to try goldfish fish - bloop bloop M - get out of that bowl and onto the bench fish - leap...splat M - do not just flop around, get the type and EMC tests done fish - flop flop bleep M - HR, do something about the fish's failure to perform HR - pounce...eat...meow M - geez you just consumed the latest worker HR - meoo? M - will have to let the compliance dog back in; come here boy. now dog. CE - woof woof slobber M - you are making a mess, get to work CE - woof, hump hump hump M - get off of my leg you degenerate compliance dog! - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
Actually there are FIVE: YES NO MAYBE DON'T KNOW DON'T CARE John Shinn, Ph.D., PE -Original Message- From: Sundstrom, Michael Sent: Thursday, December 01, 2011 10:55 AM To: John Woodgate ; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Quasi-peak Richard Schultz (of ANSI C63) always told me there were 3 answer to any EMC question asking about 'if' it will affect something? YES NO MAYBE I'd guess Mr. Schultz knew enough to say that! Michael Sundstrom OHD / TREQ Dallas Electronic Lab Analyst, EMC Lead 2170 French Settlement Rd, Suite B Dallas, Texas 75212 (214) 579 6312 (940) 390 3644c KB5UKT Albert Einstein once said, The definition of insanity is doing the same thing over and over again and expecting different results. -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Thursday, December 01, 2011 12:22 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak In message 2b83256001484461b5f6adf4c41df...@tamuracorp.com, dated Thu, 1 Dec 2011, Brian Oconnell oconne...@tamuracorp.com writes: But the question remains - does this spread-spectrum stuff, for a comparative power level, increase or decrease interference with my master-blaster 5000 remote toilet controller? As is very common with such EMC questions, the answer is a definite 'maybe'. Closely define the environment, separation and the immunity characteristics of your robot loo and you may get a slightly more definite 'maybe'. -- 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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] Quasi-peak
Maybe Six!! YES NO MAYBE DON'T KNOW DON'T CARE How much money left in the budget? Ed Price ed.pr...@cubic.com blocked::mailto:ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military Avionics EMC Is Our Specialty -Original Message- From: John Shinn [mailto:jmsh...@pacbell.net] Sent: Thursday, December 01, 2011 4:56 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak Actually there are FIVE: YES NO MAYBE DON'T KNOW DON'T CARE John Shinn, Ph.D., PE -Original Message- From: Sundstrom, Michael Sent: Thursday, December 01, 2011 10:55 AM To: John Woodgate ; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Quasi-peak Richard Schultz (of ANSI C63) always told me there were 3 answer to any EMC question asking about 'if' it will affect something? YES NO MAYBE I'd guess Mr. Schultz knew enough to say that! Michael Sundstrom OHD / TREQ Dallas Electronic Lab Analyst, EMC Lead 2170 French Settlement Rd, Suite B Dallas, Texas 75212 (214) 579 6312 (940) 390 3644c KB5UKT Albert Einstein once said, The definition of insanity is doing the same thing over and over again and expecting different results. -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Thursday, December 01, 2011 12:22 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Quasi-peak In message 2b83256001484461b5f6adf4c41df...@tamuracorp.com, dated Thu, 1 Dec 2011, Brian Oconnell oconne...@tamuracorp.com writes: But the question remains - does this spread-spectrum stuff, for a comparative power level, increase or decrease interference with my master-blaster 5000 remote toilet controller? As is very common with such EMC questions, the answer is a definite 'maybe'. Closely define the environment, separation and the immunity characteristics of your robot loo and you may get a slightly more definite 'maybe'. -- 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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
[PSES] Latest Technical Tidbit - heat sink tines and EMC
Hi All, Here is my latest technical article: Technical Tidbit - December 2011 Measuring the Resonant Frequencies Of Heat Sink Tines (Your heat sink can be the source of high frequency EMC emissions!) This month's Technical Tidbit describes a method for measuring the resonant frequencies of heat sink tines. Abstract:Heat sinks on ICs can be a source of emissions at high frequencies in the multi-GHz range. A method of identifying high risk frequencies by measuring the resonant frequencies of the heat sink tines is discussed. The link is: http://emcesd.com/tt2011/tt120111.htm Doug -- --- ___ _ Doug Smith \ / ) P.O. Box 1457 = Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-( ) | o |Email: d...@dsmith.org \ _ /]\ _ / Website: http://www.dsmith.org --- - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas 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
