Hi Ken,
>From your response, you probably don’t know Alvin very well if at all. You can say a lot of things about Alvin (and I probably have :-) ) but embarrassing the profession isn’t one of them. But backing off from the personal issues, your response didn’t really address the question of where the limits come from. Having participated in standards making committees, I would have to say that there is as much political posturing as engineering going on. I seriously doubt that there is any scientific investigation that points to 1, 3, 10 V/m providing adequate protection for certain environments. I always assumed that the standards committee picked these numbers because they looked good on a logarithmic chart. It would be informative if someone on the forum was actually a member of the original CISPR committee and could refute my [perhaps] jaded experience. …Marko ________________________________ From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Friday, October 30, 2009 11:22 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Where does 3V/m & 10V/m in RI come from? The only thing right about that post is the disclaimer, and that is only if you have an odd sense of humor. RE limits are set to protect broadcast radio reception, while RI/RS limits are set to bracket intentional transmitters. The margin between receivers and transmitters is between femto- and picowatt sensitivity and Watt or higher level transmission. If you make the apples to rocks comparison of RE to RI/RS limits the “margins” you come up with are on the order of 80 dB or higher. Is there another engineering discipline that enforces that sort of margin? Can you envision a bridge or building built with such margins? Would an airplane ever get built, much less leave the ground? And that Ares rocket that just launched successfully yesterday? What would lift-off look like with an 80 dB increase in mass, huh? Granted the previous post was in jest, but too many people take that sort of thing at face value. This is embarrassing to the profession. Ken Javor Phone: (256) 650-5261 ________________________________ From: "Ilarina, Alvin" <alvin.ilar...@plantronics.com> List-Post: emc-pstc@listserv.ieee.org List-Post: emc-pstc@listserv.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Fri, 30 Oct 2009 10:30:53 -0700 To: "Kunde, Brian" <brian_ku...@lecotc.com>, <EMC-PSTC@LISTSERV.IEEE.ORG> Conversation: Where does 3V/m & 10V/m in RI come from? Subject: RE: Where does 3V/m & 10V/m in RI come from? IIRC the radiated immunity limits are set at X dB of something above the emissions limits creating a guard band. The theory being that there is a built in tolerance between the allowable emissions in the field and the level at which equipment is supposed to begin to be susceptible. I think I heard this explanation off-line from one of the “old men of EMC” at one of our conferences/symposiums years ago. We were most likely consuming alcohol at the time. This might just be urban legend. Alvin Disclaimer: The contents reflect the opinion of the author and are meant for entertainment purposes only. ________________________________ From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] <mailto:emc-p...@ieee.org%5d> On Behalf Of Kunde, Brian Sent: Thursday, October 29, 2009 10:18 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Where does 3V/m & 10V/m in RI come from? Simple question, where does the 1V/m, 3V/m and 10V/m test levels come from in the Radiated Immunity standards such as IEC/EN61000-4-3? Is there some real-world rf source that correlates to these levels? Thanks for the history lesson. 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