Hello Paolo, Group, If any PC source creates a common mode current flowing through your LAN card, then into the UTP cable then this current will show up as "conducted emission". Its not the data that radiates, it's noise from the PC board. As soon as the LAN cable gets long enough, it will radiate : that's the outside world in my humble opinion.
Conducted emission does not have to stay conducted. This test is also to control low frequency ( < 30 Mhz) radiated emissions. STP will fix that, if the RJ connector permits the shield to connect VERY WELL to the LAN's card bracket AND the bracket is WELL inserted in WELL constructed PC enclosure. Three conditions, of which most often at least one fails to be fully compliant in many STP networks. The dataflow of a CAT5 UTP cable WILL NOT contribute to any interference. if it did so, the card would not work. Data will arrive too distorted at the other side. Not even if it is running close to other wiring. The twisting effect will compensate for every mutual coupling in neighboring cables. (unless a CM current exists !) How do you think ADSL modems work on ordinary (often unshielded) phone cables (not even CAT 5). Or just plain old ISDN data over miles of phone wire without radiating. UTP will often get interfered however due to CM capacitive 50/60 Hz coupling (E-field) This drives the receiver out of it's common mode range ( or if transformer coupled, the CMMRR of it is too bad, effectively transferring CM voltage into DM voltage). STP will help here too (but better/cheaper solutions exist : personal experience!). Modern 100 MHZ LAN data transfer over a 2 wire non coaxial cable is real high Tec. A friend of my replaced a 5 meter CAT5 cable by 1 meter of ordinary telephone cable (twisted) It did not work. To my opinion, STP is not necessary and is often erroneously prescribed: a waist of money. Regards, Gert Gremmen, (Ing) ce-test, qualified testing =============================================== Web presence http://www.cetest.nl CE-shop http://www.cetest.nl/ce_shop.htm /-/ Compliance testing is our core business /-/ =============================================== >>-----Original Message----- >>From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf >>Of Paolo Roncone >>Sent: Thursday, September 07, 2000 4:45 PM >>To: 'eric.lif...@ni.com' >>Cc: 'emc-p...@ieee.org' >>Subject: R: Conducted Emissions on Telecom Ports >> >> >> >>Hi Eric, >> >>I 100% agree with you. The scope of emissions standard should be >>to protect the "outside" (i.e. public) environment from >>interference. So only ports that connect to public telecom >>networks should be covered by the standard. The problem is (as >>pointed out in one of the previous notes) that the new CISPR22 / >>EN55022 standard clearly includes LAN ports in the definition of >>telecommunications ports (section 3.6) no matter if they connect >>to the "outside world" or not. >> >>Regards, >> >>Paolo Roncone >>Compuprint s.p.a. >>Italy >> >>-----Messaggio originale----- >>Da: eric.lif...@ni.com [SMTP:eric.lif...@ni.com] >>Inviato: mercoledì 6 settembre 2000 17.55 >>A: emc-p...@ieee.org >>Oggetto: Re: Conducted Emissions on Telecom Ports >> >> >>All, >> >>As a not-quite-outside-observer (strictly EN 55011 here) of this >>thread, it's >>not fun seeing LAN ports classified as telecom; IMO that's >>overkill for the >>folks using EN 55022. >> >>Up till now, I considered a port to be telecom only if it >>connects a client >>facility to a carrier's network (DSL, ISDN, T1 and so on). >> >>With repeaters every 5 meters, USB and 1394 can support a bus >>long enough to >>connect between adjacent buildings. So, I wonder if some fanatic >>will soon be >>promoting USB/1394 ports as telecom? >> >>If Chris is right, and the EN 55022 version of the old telecom >>port conducted >>emission standard was intended to protect other telecom signals >>in a bundle, >>then I would think that this test is clearly redundant to the >>immunity tests >>(61000-4-6 and -4-3) that offer the needed protection from the other end. >> >>Does this emission requirement appear to be a waste of time and >>money to anyone >>else? >> >>Regards, >>Eric Lifsey >>Compliance Manager >>National Instruments >> >> >> >> >> >> >>Please respond to "Chris Allen" <chris_al...@eur.3com.com> >> >>To: "Pryor McGinnis" <c...@prodigy.net> >>cc: david_ster...@ademco.com, emc-p...@ieee.org, >> gary.mcintu...@worldwidepackets.com, "John Moore" >> <john_mo...@eur.3com.com> (bcc: Eric Lifsey/AUS/NIC) >> >>Subject: Re: Conducted Emissions on Telecom Ports >> >> >>Pryor, >> >>Unfortunately, I don't think the definition is in question. It >>specifically >>states, that for the purposes of the standard, LANs are to be >>considered as >>telecomms ports as per section 3.6. It probably would have been >>less ambiguous >>if the standard defined Telecomms ports as "Ports which are intended to be >>connected to the telecomms network OR LANs OR similar networks. >> >>As far as enforcement goes this will not change from the current method of >>enforcing compliance, primarily via the end user requesting DoCs and the >>relevent test data to back this document up. >> >>I believe the requirement goes back to a test that was performed >>under either >>VDE 0805 or 0806 (it was a long time ago that I had to perform >>the test). It was >>specifically aimed at unscreened cables over a certain length >>being placed in >>cable ducts and their impact on adjacent telecomms cables (if >>anybody remebers >>StarLan this was the product I was involved in). >> >>Chris. >> >> >> >> >> >>"Pryor McGinnis" <c...@prodigy.net> on 05/09/2000 20:54:51 >> >>Please respond to "Pryor McGinnis" <c...@prodigy.net> >> >>Sent by: "Pryor McGinnis" <c...@prodigy.net> >> >> >>To: david_ster...@ademco.com, emc-p...@ieee.org, >> gary.mcintu...@worldwidepackets.com >>cc: (Chris Allen/GB/3Com) >>Subject: Re: Conducted Emissions on Telecom Ports >> >> >>I do not disagree with the positions posted on this subject. My >>question is >>how does the EU interpret and enforce this requirement/definition. >> >>Pryor >> >>----- Original Message ----- >>From: <david_ster...@ademco.com> >>To: <emc-p...@ieee.org>; <gary.mcintu...@worldwidepackets.com> >>Sent: Tuesday, September 05, 2000 2:07 PM >>Subject: RE: Conducted Emissions on Telecom Ports >> >> >>> >>> LAN ports >>> Testing Conducted RF Emissions on LAN twisted-pair lines is almost >>> contrary to the intent of EN 55022 as Gary pointed out. Conducted >>> emissions is more appropriate for asynchronous analog lines. >>> >>> LAN transmissions are digital and synchronous (except >>maybe ATM); the >>> receiver part of the interface circuitry locks onto the >>frequency of >>> data, rejecting spurious frequencies. The signals are >>truely digital, >>> not analog as in a modem. >>> >>> Arcnet, Ethernet, and Fast Ethernet TP cabling links two points >>(node, >>> hub, switch, bridge) which digitally reconstitute the signal, >>> eliminating spurious cable frequencies. >>> >>> Token-Ring is peer-peer, usually through a passive hub. Each node >>> (peer) reconstitutes the signal as above. >>> >>> Ethernet, F-E and Token-Ring ANSI/IEEE or ISO/IEC physical layer >>> requirements define interfaces, cable lengths/type(s) and timing. >>> >>> Coax cable rules for Arcnet, 10Base2 Ethernet) permit connection to >>> multiple nodes but again, the digital nature of the signals and the >>> well-defined connectivity rules prevent problems. >>> >>> David >>> >>> >>> ______________________________ Reply Separator >>> _________________________________ >>> Subject: RE: Conducted Emissions on Telecom Ports >>> Author: "Gary McInturff" <SMTP:gary.mcintu...@worldwidepackets.com> at >>> ADEMCONET >>> Date: 9/5/2000 10:54 AM >>> >>> >>> Define telecom port. >>> A LAN port isn't neccessarily a LAN port. Ethernet ports do not >>> connect directly to the Telecommunications network - a >>necessary condition >>> before being a telecommunications port. LANS and MANS operate all of the >>> time without any use of any telecommunications equipment. Generally, >>> Ethernet or Fast Ethernet for short distances and Gig Ethernet >>for longer >>> distances. IF -- the telecommunications lines are needed there is some >>sort >>> of "bridge" that takes the ethernet and its digitized Voice >>over Internet >>> Protocol (Voip) and does all of the phone stuff and makes the actual >>> metallic connection. That "birdge" has the only >>telecommunication ports on >>> it. >>> Gary >>> >>> >>> -----Original Message----- >>> From: Pryor McGinnis [mailto:c...@prodigy.net] >>> Sent: Thursday, August 31, 2000 6:24 AM >>> To: Pettit, Ghery; david_ster...@ademco.com; emc-p...@ieee.org >>> Subject: Re: Conducted Emissions on Telecom Ports >>> >>> >>> >>> Confusing isn't? >>> >>> ----- Original Message ----- >>> From: Pettit, Ghery <ghery.pet...@intel.com> >>> To: <david_ster...@ademco.com>; <emc-p...@ieee.org>; <c...@prodigy.net> >>> Sent: Wednesday, August 30, 2000 5:40 PM >>> Subject: RE: Conducted Emissions on Telecom Ports >>> >>> >>> > Actually, it's August 1, 2001 as posted in the OJ on January 25th of >>this >>> > year. You've got 1 less month to start testing to the new standard. >>> > >>> > Ghery Pettit >>> > Intel >>> > >>> > >>> > -----Original Message----- >>> > From: david_ster...@ademco.com [mailto:david_ster...@ademco.com] >>> > Sent: Wednesday, August 30, 2000 2:04 PM >>> > To: emc-p...@ieee.org; c...@prodigy.net >>> > Subject: RE: Conducted Emissions on Telecom Ports >>> > >>> > >>> > >>> > The date of withdrawal of EN 55022:1998 is September 1, >>2001. Look >>> at >>> > the NIC manual's DofC --- the mfgr. may not be declaring >>compliance >>> to >>> > conducted emissions yet. >>> > >>> > >>> > ______________________________ Reply Separator >>> > _________________________________ >>> > Subject: Re: Conducted Emissions on Telecom Ports >>> > Author: "Pryor McGinnis" <SMTP:c...@prodigy.net> at ADEMCONET >>> > Date: 8/30/2000 10:31 AM >>> > >>> > >>> > Hello All, >>> > >>> > The question originated from a manufacturer of LAN boards who sells to >>end >>> >>> > users and to manufacturer's who integrate the LAN boards into end >>> products. >>> > >>> > I advised the LAN board manufacturer that conducted emissions would be >>> > required (with boards installed in typical host) on all LAN >>boards sold >>to >>> >>> > end users and manufacturers of products that integrated LAN boards >>should >>> > test the ports for conducted emission in their end product. The LAN >>board >>> >>> > manufacturer questioned double testing of the LAN boards. His concern >>is >>> > that boards that pass CE in a typical host may not pass in another >>> > manufacturer's end product (rub of the green). The LAN Board >>> manufacturer >>> > ask for second opinions. >>> > >>> > Many thanks for your answers. >>> > >>> > Best Regards, >>> > Pryor >>> > >>> > > -----Original Message----- >>> > > From: Pryor McGinnis [SMTP:c...@prodigy.net] >>> > > Sent: Tuesday, August 29, 2000 12:35 PM >>> > > To: emc-pstc >>> > > Subject: Conducted Emissions on Telecom Ports >>> > > >>> > > Below is a message from a non emc-pstc member. >>> > > >>> > > If a manufacturer purchases LAN boards which have been tested for >>> > > conducted emissions in a host, is the manufacturer required >>to retest >>> the >>> > > LAN Ports for conducted emissions if the manufacturer sells his >>product >>> > with >>> > > the LAN board installed? >>> > > >>> > > I am very interested in your comments. >>> > > >>> > > >>> > > Best Regards, >>> > > Pryor McGinnis >>> > > c...@prodigy.net <mailto:c...@prodigy.net> >>> > > www.ctl-lab.com <http://www.ctl-lab.com> >>> > > >>> > > ------------------------------------------- >> >> >> >> >> >> >> >> >> >> >>------------------------------------------- >>This message is from the IEEE EMC Society Product Safety >>Technical Committee emc-pstc discussion list. >> >>To cancel your subscription, send mail to: >> majord...@ieee.org >>with the single line: >> unsubscribe emc-pstc >> >>For help, send mail to the list administrators: >> Jim Bacher: jim_bac...@mail.monarch.com >> Michael Garretson: pstc_ad...@garretson.org >> >>For policy questions, send mail to: >> Richard Nute: ri...@ieee.org >> >> >>------------------------------------------- >>This message is from the IEEE EMC Society Product Safety >>Technical Committee emc-pstc discussion list. >> >>To cancel your subscription, send mail to: >> majord...@ieee.org >>with the single line: >> unsubscribe emc-pstc >> >>For help, send mail to the list administrators: >> Jim Bacher: jim_bac...@mail.monarch.com >> Michael Garretson: pstc_ad...@garretson.org >> >>For policy questions, send mail to: >> Richard Nute: ri...@ieee.org >> >>
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