RE: R: R: Conducted Emissions on Telecom Ports
The defined I/O coupling methods for EN55022:1997 do not appear to accurately depict real-world shielding provided by twisted pair wiring, almost as if the test method were rigged against passing EMI with T-P cable. Considerable study went into development of twisted pair connectivity rules for each ANSI/IEEE 802.x LAN technology, emissions, immunity, cable grade etc., including coupling (remember TokenRing was 4 and 16 MHz, and Ethernet was 10 MHz so the harmonics were there). David __ Reply Separator _ Subject: Re: R: R: Conducted Emissions on Telecom Ports Author: Ken Javor SMTP:ken.ja...@emccompliance.com at ADEMCONET List-Post: emc-pstc@listserv.ieee.org Date:9/8/2000 5:31 PM The point is that RE/CE protect broadcast bands. Making an RE measurement (E or H field, regardless) from a LAN line a couple meters long is not representative of what you would measure if the LAN line were significantly longer, as it might be in situ. Therefore a CE measurement can be better correlated to predicted RE from a much longer line (at frequencies where the tested LAN line is electrically short. -- From: Paolo Roncone paolo.ronc...@compuprint.it To: 'Ken Javor' ken.ja...@emccompliance.com, 'Cortland Richmond' 72146@compuserve.com Cc: 'emc-p...@ieee.org' emc-p...@ieee.org Subject: R: R: Conducted Emissions on Telecom Ports Date: Fri, Sep 8, 2000, 3:51 AM Ken and Cortland and many others that entered this subject : First, radiated emissions are best measured with radiated (not conducted) measurements. There is a correlation between CM currents and RE but that's not all (resonances, cable layout etc. count a lot). Second, you say that CE are easier to measure than RE ? Agree if you talk about emissions on AC power cords (as per CISPR22 and FCC part 15). But for the new requirements on telecom ports, I suggest you to take a look at the new (3.ed.) CISPR22 or EN55022 (sec. 9.5 + annex C.1) and may be you change your opinion ! Radiated emissions above 30 MHz are already covered. If you wanna take care of lower frequencies ( 30 MHz) take a loop antenna (remember the old VDE rules ?) and measure radiated H-fields with your system in the same (typical) layout used for the higher frequencies (with whatever cables you specify, UTS, STP etc.). I am sure that is much quicker, easier and repeatable than all the nonsense (ISNs, CDNs, clamps, current probes, capacitive probes, ferrites, 150 ohm resistors, signal generators, impedance measurements, voltage measurements, current measurements and more) in the new CISPR22. As for the question of outside world, I think in this ever more connected world the border line between INSIDE and OUTSIDE is getting more and more blurred, BUT I also think that a line must be drawn by the standard bodies, otherwise it's gonna really get too much confusing (hope some CISPR/CENELEC member gets it). If we spill over the line (office, floor, building... whatever), emissions requirements are triggered. But within that line it's to be considered an intra-system (what's the system ? that's another good question to be settled) interference potential and the manufacturer should take care of it without need of enforcement because he has all the interest in making a product (system) that works properly and reliably. One last point: based on David Sterner's note, looks to me that North America has a pretty extensive Ethernet and-the-like network. I honestly don't know if the FCC has already enforced emission limits on LAN ports. Anyway, based on David's note looks like there are no complaits of interference with TV and telephones. And please note, this is the very bottom line of it. Emission limits should be intended to protect public services ... and physics works the same on both sides of the Atlantic... or not My personal opinion ... Paolo -Messaggio originale- Da: Ken Javor [SMTP:ken.ja...@emccompliance.com] Inviato: giovedì 7 settembre 2000 18.43 A: Paolo Roncone; 'eric.lif...@ni.com' Cc: 'emc-p...@ieee.org' Oggetto: Re: R: Conducted Emissions on Telecom Ports Although I don't work commercial EMC on a regular basis and I do not know over what frequency range the telecom port CE are controlled (I assume here 150 kHz - 30 MHz), I believe that there is a mistaken premise inherent in the comments to which I am responding. The purpose of controlling common mode CE on any port is not to protect equipment at the other end of the cable, or other co-sited cables, but rather to control radiated emissions in a frequency range in which CE are easier to measure than RE. In turn, the purpose of controlling RE is to protect broadcast radio reception. -- From: Paolo Roncone paolo.ronc...@compuprint.it To: 'eric.lif...@ni.com' eric.lif
Re: R: Conducted Emissions on Telecom Ports
Steve: Please tell me more about the immunity standards- they are non existent in Canada Ralph Cameron EMC Consulting and Suppression of Consumer Electronic Equipment (After sale) p.s Ever listen to the radio near some home treadmills? - Original Message - From: Steve Grobe ste...@transition.com To: ieee pstc list emc-p...@ieee.org Sent: Thursday, September 07, 2000 1:35 PM Subject: RE: R: Conducted Emissions on Telecom Ports Has anyone seen problems with ethernet and conducted emissions? I have a home office with 4 PCs networked with ethernet running over UTP and I haven't seen much of a problem. Granted, the longest cable run I have is to a file server in the basement (about 10 meters) but both my AM radio and my shortwave set seem to work just fine. The only thing I remember picking up is 20MHz on the shortwave set. (Most 10Mbit ethernet devices use a 20MHz clock.) At work we have both 10 and 100Mbit ethernet (150-200 nodes) and the AM reception is really bad but I attribute that to the building (big steel and brick box) more than noise as reception improves as you get closer to a window. I haven't tried the shortwave at work being that shortwave reception is usually bad during the day anyway. As far as telephone lines are concerned my ears don't pick up much noise above 19kHz. I would think anything else would be covered by immunity standards. Steve -Original Message- From: Cortland Richmond [mailto:72146@compuserve.com] Sent: Thursday, September 07, 2000 11:01 AM To: Paolo Roncone; ieee pstc list Subject: Re: R: Conducted Emissions on Telecom Ports Paolo Roncone wrote: 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. I disagree. The purpose of emissions standards is to prevent interference. Some are to similar functions, some are to other media. There is no interface for interference at which point the manufacturer may say: Interference when you use this isn't our problem. We may say: Use shielded cable, or Put a ferrite on your cable, but we can't evade the physical fact that it is our own equipment which is the source of interference, and the cable is its antenna. It does not matter that we do not own the cable; if you plug it in and there is interference, it is up to the people who made the equipment to see the interference reduced. There is no transfer of ownership for radio waves. Granted, to call a LAN cable telecommunications is a clumsy construction of the regulation. But those who grasp at that straw to save a few currency units will find themselves later regretting that they have done so. If you are beaten and robbed for a display of wealth, it is no use protesting that the money was counterfeit. Cortland Richmond (I speak for myself alone and not for my employer) == Original Message Follows Date: 07-Sep-00 07:48:16 MsgID: 1072-46656 ToID: 72146,373 From: Paolo Roncone INTERNET:paolo.ronc...@compuprint.it Subj: R: Conducted Emissions on Telecom Ports Chrg: $0.00 Imp: Norm Sens: StdReceipt: NoParts: 1 From: Paolo Roncone paolo.ronc...@compuprint.it Subject: R: Conducted Emissions on Telecom Ports Date: Thu, 7 Sep 2000 16:45:03 +0200 Reply-To: Paolo Roncone paolo.ronc...@compuprint.it 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
Re: R: R: Conducted Emissions on Telecom Ports
The point is that RE/CE protect broadcast bands. Making an RE measurement (E or H field, regardless) from a LAN line a couple meters long is not representative of what you would measure if the LAN line were significantly longer, as it might be in situ. Therefore a CE measurement can be better correlated to predicted RE from a much longer line (at frequencies where the tested LAN line is electrically short. -- From: Paolo Roncone paolo.ronc...@compuprint.it To: 'Ken Javor' ken.ja...@emccompliance.com, 'Cortland Richmond' 72146@compuserve.com Cc: 'emc-p...@ieee.org' emc-p...@ieee.org Subject: R: R: Conducted Emissions on Telecom Ports Date: Fri, Sep 8, 2000, 3:51 AM Ken and Cortland and many others that entered this subject : First, radiated emissions are best measured with radiated (not conducted) measurements. There is a correlation between CM currents and RE but that's not all (resonances, cable layout etc. count a lot). Second, you say that CE are easier to measure than RE ? Agree if you talk about emissions on AC power cords (as per CISPR22 and FCC part 15). But for the new requirements on telecom ports, I suggest you to take a look at the new (3.ed.) CISPR22 or EN55022 (sec. 9.5 + annex C.1) and may be you change your opinion ! Radiated emissions above 30 MHz are already covered. If you wanna take care of lower frequencies ( 30 MHz) take a loop antenna (remember the old VDE rules ?) and measure radiated H-fields with your system in the same (typical) layout used for the higher frequencies (with whatever cables you specify, UTS, STP etc.). I am sure that is much quicker, easier and repeatable than all the nonsense (ISNs, CDNs, clamps, current probes, capacitive probes, ferrites, 150 ohm resistors, signal generators, impedance measurements, voltage measurements, current measurements and more) in the new CISPR22. As for the question of outside world, I think in this ever more connected world the border line between INSIDE and OUTSIDE is getting more and more blurred, BUT I also think that a line must be drawn by the standard bodies, otherwise it's gonna really get too much confusing (hope some CISPR/CENELEC member gets it). If we spill over the line (office, floor, building... whatever), emissions requirements are triggered. But within that line it's to be considered an intra-system (what's the system ? that's another good question to be settled) interference potential and the manufacturer should take care of it without need of enforcement because he has all the interest in making a product (system) that works properly and reliably. One last point: based on David Sterner's note, looks to me that North America has a pretty extensive Ethernet and-the-like network. I honestly don't know if the FCC has already enforced emission limits on LAN ports. Anyway, based on David's note looks like there are no complaits of interference with TV and telephones. And please note, this is the very bottom line of it. Emission limits should be intended to protect public services ... and physics works the same on both sides of the Atlantic... or not My personal opinion ... Paolo -Messaggio originale- Da: Ken Javor [SMTP:ken.ja...@emccompliance.com] Inviato: giovedì 7 settembre 2000 18.43 A: Paolo Roncone; 'eric.lif...@ni.com' Cc: 'emc-p...@ieee.org' Oggetto: Re: R: Conducted Emissions on Telecom Ports Although I don't work commercial EMC on a regular basis and I do not know over what frequency range the telecom port CE are controlled (I assume here 150 kHz - 30 MHz), I believe that there is a mistaken premise inherent in the comments to which I am responding. The purpose of controlling common mode CE on any port is not to protect equipment at the other end of the cable, or other co-sited cables, but rather to control radiated emissions in a frequency range in which CE are easier to measure than RE. In turn, the purpose of controlling RE is to protect broadcast radio reception. -- From: Paolo Roncone paolo.ronc...@compuprint.it To: 'eric.lif...@ni.com' eric.lif...@ni.com Cc: 'emc-p...@ieee.org' emc-p...@ieee.org Subject: R: Conducted Emissions on Telecom Ports Date: Thu, Sep 7, 2000, 9:45 AM 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 --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail
RE: R: Conducted Emissions on Telecom Ports
Paolo, Physics does work the same on both side of the Atlantic, but human rationale does not necessarily! Tania Grant, tgr...@lucent.com Lucent Technologies, Switching Solutions Group Intelligent Network and Messaging Solutions -- From: Paolo Roncone[SMTP:paolo.ronc...@compuprint.it] Reply To: Paolo Roncone Sent: Friday, September 08, 2000 3:51 AM To: 'Ken Javor'; 'Cortland Richmond' Cc: 'emc-p...@ieee.org' Subject: R: R: Conducted Emissions on Telecom Ports Ken and Cortland and many others that entered this subject : First, radiated emissions are best measured with radiated (not conducted) measurements. There is a correlation between CM currents and RE but that's not all (resonances, cable layout etc. count a lot). Second, you say that CE are easier to measure than RE ? Agree if you talk about emissions on AC power cords (as per CISPR22 and FCC part 15). But for the new requirements on telecom ports, I suggest you to take a look at the new (3.ed.) CISPR22 or EN55022 (sec. 9.5 + annex C.1) and may be you change your opinion ! Radiated emissions above 30 MHz are already covered. If you wanna take care of lower frequencies ( 30 MHz) take a loop antenna (remember the old VDE rules ?) and measure radiated H-fields with your system in the same (typical) layout used for the higher frequencies (with whatever cables you specify, UTS, STP etc.). I am sure that is much quicker, easier and repeatable than all the nonsense (ISNs, CDNs, clamps, current probes, capacitive probes, ferrites, 150 ohm resistors, signal generators, impedance measurements, voltage measurements, current measurements and more) in the new CISPR22. As for the question of outside world, I think in this ever more connected world the border line between INSIDE and OUTSIDE is getting more and more blurred, BUT I also think that a line must be drawn by the standard bodies, otherwise it's gonna really get too much confusing (hope some CISPR/CENELEC member gets it). If we spill over the line (office, floor, building... whatever), emissions requirements are triggered. But within that line it's to be considered an intra-system (what's the system ? that's another good question to be settled) interference potential and the manufacturer should take care of it without need of enforcement because he has all the interest in making a product (system) that works properly and reliably. One last point: based on David Sterner's note, looks to me that North America has a pretty extensive Ethernet and-the-like network. I honestly don't know if the FCC has already enforced emission limits on LAN ports. Anyway, based on David's note looks like there are no complaits of interference with TV and telephones. And please note, this is the very bottom line of it. Emission limits should be intended to protect public services ... and physics works the same on both sides of the Atlantic... or not My personal opinion ... Paolo -Messaggio originale- Da: Ken Javor [SMTP:ken.ja...@emccompliance.com] Inviato: giovedì 7 settembre 2000 18.43 A:Paolo Roncone; 'eric.lif...@ni.com' Cc: 'emc-p...@ieee.org' Oggetto: Re: R: Conducted Emissions on Telecom Ports Although I don't work commercial EMC on a regular basis and I do not know over what frequency range the telecom port CE are controlled (I assume here 150 kHz - 30 MHz), I believe that there is a mistaken premise inherent in the comments to which I am responding. The purpose of controlling common mode CE on any port is not to protect equipment at the other end of the cable, or other co-sited cables, but rather to control radiated emissions in a frequency range in which CE are easier to measure than RE. In turn, the purpose of controlling RE is to protect broadcast radio reception. -- From: Paolo Roncone paolo.ronc...@compuprint.it To: 'eric.lif...@ni.com' eric.lif...@ni.com Cc: 'emc-p...@ieee.org' emc-p...@ieee.org Subject: R: Conducted Emissions on Telecom Ports Date: Thu, Sep 7, 2000, 9:45 AM 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 --- 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
RE: R: R: Conducted Emissions on Telecom Ports
All, As Ghery reported before (lost in the recent threads, but copied below), the closely related issue cf definition creepage is being addressed by CISPR SC G and is already is CDV stage but not yet FDIS. If it isn't already too late, this might be the best or only opportunity we'll get for bring the issue up for discussion in a CISPR committee within the next couple of years. This would be the opportunity to bring together in some way (?) the designers of Ethernet and the CISPR committee, so whatever the outcome we can agree the issue was examined with due engineering dilligence. Regards, Eric Lifsey Please respond to Pettit, Ghery ghery.pet...@intel.com To: Eric Lifsey/AUS/NIC@NIC, emc-p...@ieee.org cc: Subject: RE: Conducted Emissions on Telecom Ports This sort of question has already come up in CISPR SC G (the owner of CISPR 22). There is a CDV (Committee Draft for Vote) being prepared that, if adopted as a Final Draft International Standard (FDIS), will put a halt to the definition creep that has been happening with this issue. The text doesn't get rid of LANs as a telecom port, but it does prevent administrations from calling things like RS-232 (yes, Australia has tried to justify this as a telecom port), USB, 1393, etc telecom ports. Nothing happens fast in the IEC, so don't hold your breath waiting for this change to happen, but we are working on it. When the CDV comes out there will be a voting period on it and if it passes, it will then be re-issued as an FDIS for final vote. I wouldn't expect any final action for at least a year or more. Ghery Pettit Intel Member, US CISPR G TAG --- 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
RE: R: R: Conducted Emissions on Telecom Ports
Paolo, You bring up an interesting point about FCC. FCC recognizes CISPR 22:1985 is as an alternative test method. The 1985 version does not specify emissions on LAN or telco. FCC Part 68 specifies conducted emissions only on mains cables over 450kHz to 30MHz with slightly different limits. There seems to be considerable interest in requesting a review of the need for conducted emissions requirements for LANS, not to mention installation cost (STP cost differential, clumsy routing, earthing considerations). What is our next step to get a formal review? David __ Reply Separator _ Subject: R: R: Conducted Emissions on Telecom Ports Author: Paolo Roncone SMTP:paolo.ronc...@compuprint.it at ADEMCONET List-Post: emc-pstc@listserv.ieee.org Date:9/8/2000 6:51 AM Ken and Cortland and many others that entered this subject : First, radiated emissions are best measured with radiated (not conducted) measurements. There is a correlation between CM currents and RE but that's not all (resonances, cable layout etc. count a lot). Second, you say that CE are easier to measure than RE ? Agree if you talk about emissions on AC power cords (as per CISPR22 and FCC part 15). But for the new requirements on telecom ports, I suggest you to take a look at the new (3.ed.) CISPR22 or EN55022 (sec. 9.5 + annex C.1) and may be you change your opinion ! Radiated emissions above 30 MHz are already covered. If you wanna take care of lower frequencies ( 30 MHz) take a loop antenna (remember the old VDE rules ?) and measure radiated H-fields with your system in the same (typical) layout used for the higher frequencies (with whatever cables you specify, UTS, STP etc.). I am sure that is much quicker, easier and repeatable than all the nonsense (ISNs, CDNs, clamps, current probes, capacitive probes, ferrites, 150 ohm resistors, signal generators, impedance measurements, voltage measurements, current measurements and more) in the new CISPR22. As for the question of outside world, I think in this ever more connected world the border line between INSIDE and OUTSIDE is getting more and more blurred, BUT I also think that a line must be drawn by the standard bodies, otherwise it's gonna really get too much confusing (hope some CISPR/CENELEC member gets it). If we spill over the line (office, floor, building... whatever), emissions requirements are triggered. But within that line it's to be considered an intra-system (what's the system ? that's another good question to be settled) interference potential and the manufacturer should take care of it without need of enforcement because he has all the interest in making a product (system) that works properly and reliably. One last point: based on David Sterner's note, looks to me that North America has a pretty extensive Ethernet and-the-like network. I honestly don't know if the FCC has already enforced emission limits on LAN ports. Anyway, based on David's note looks like there are no complaits of interference with TV and telephones. And please note, this is the very bottom line of it. Emission limits should be intended to protect public services ... and physics works the same on both sides of the Atlantic... or not My personal opinion ... Paolo -Messaggio originale- Da: Ken Javor [SMTP:ken.ja...@emccompliance.com] Inviato: giovedì 7 settembre 2000 18.43 A: Paolo Roncone; 'eric.lif...@ni.com' Cc: 'emc-p...@ieee.org' Oggetto: Re: R: Conducted Emissions on Telecom Ports Although I don't work commercial EMC on a regular basis and I do not know over what frequency range the telecom port CE are controlled (I assume here 150 kHz - 30 MHz), I believe that there is a mistaken premise inherent in the comments to which I am responding. The purpose of controlling common mode CE on any port is not to protect equipment at the other end of the cable, or other co-sited cables, but rather to control radiated emissions in a frequency range in which CE are easier to measure than RE. In turn, the purpose of controlling RE is to protect broadcast radio reception. -- From: Paolo Roncone paolo.ronc...@compuprint.it To: 'eric.lif...@ni.com' eric.lif...@ni.com Cc: 'emc-p...@ieee.org' emc-p...@ieee.org Subject: R: Conducted Emissions on Telecom Ports Date: Thu, Sep 7, 2000, 9:45 AM 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
Re: R: Conducted Emissions on Telecom Ports
Ken, that is not what Mike is saying. Mike's statment was to the effect that if the noise can get out of the EUT then noise from another source can get in. A point of exit can also be a point of entry for EMI. This applies to all types of launching mechanisms, not just cables. Also, just because a piece of equipemnt is passing CE or any emissions does not guarrenty that it will not cause a problem with other equipment. Coupling between adjacent cabling can cause EMC issues even if both unit pass CE. Primarily, all emissions limits, CE and RE, exist to provide a level of protection for communitcations over the air. Equipment protection is secondary. Keeping equipment clean at the source goes a long way to protect it from outside influences. Guy Story, KC5GOI Compliance Technician Interphase Corporation Dallas Texas phone: 214.654.5161 fax: 214.654.5406 - Original Message - From: Ken Javor ken.ja...@emccompliance.com To: michael.sundst...@nokia.com; paolo.ronc...@compuprint.it; eric.lif...@ni.com Cc: emc-p...@ieee.org Sent: Thursday, September 07, 2000 10:17 PM Subject: Re: R: Conducted Emissions on Telecom Ports So you are saying that an emission limit was imposed to improve immunity of the self-same equipment? I have to go on record disagreeing with that interpretation. As for protection of nearby circuits, my guess is that if you calculate coupling from a cable just meeting your telecom port CE limit to an adjacent cable, you will find that even common mode coupling is orders of magnitude below the intentional signal carried in the adjacent victim cable. I say this in full ignorance of just what that CE limit is, since I know that a CE limit designed to protect against rfi will more than protect against cable-to-cable coupling. -- From: michael.sundst...@nokia.com To: ken.ja...@emccompliance.com, paolo.ronc...@compuprint.it, eric.lif...@ni.com Cc: emc-p...@ieee.org Subject: RE: R: Conducted Emissions on Telecom Ports Date: Thu, Sep 7, 2000, 5:01 PM Actually it's to reduce interference to one's own equipment, (if it emits it - it's also susceptible to it). It also has the effect of reducing interference to other near by equipment. Michael Sundstrom Nokia Mobile Phones, PCC EMC Technician cube 4E : 390B phone: 972-374-1462 mobile: 817-917-5021 michael.sundst...@nokia.com amateur call: KB5UKT --- 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
R: R: Conducted Emissions on Telecom Ports
Ken and Cortland and many others that entered this subject : First, radiated emissions are best measured with radiated (not conducted) measurements. There is a correlation between CM currents and RE but that's not all (resonances, cable layout etc. count a lot). Second, you say that CE are easier to measure than RE ? Agree if you talk about emissions on AC power cords (as per CISPR22 and FCC part 15). But for the new requirements on telecom ports, I suggest you to take a look at the new (3.ed.) CISPR22 or EN55022 (sec. 9.5 + annex C.1) and may be you change your opinion ! Radiated emissions above 30 MHz are already covered. If you wanna take care of lower frequencies ( 30 MHz) take a loop antenna (remember the old VDE rules ?) and measure radiated H-fields with your system in the same (typical) layout used for the higher frequencies (with whatever cables you specify, UTS, STP etc.). I am sure that is much quicker, easier and repeatable than all the nonsense (ISNs, CDNs, clamps, current probes, capacitive probes, ferrites, 150 ohm resistors, signal generators, impedance measurements, voltage measurements, current measurements and more) in the new CISPR22. As for the question of outside world, I think in this ever more connected world the border line between INSIDE and OUTSIDE is getting more and more blurred, BUT I also think that a line must be drawn by the standard bodies, otherwise it's gonna really get too much confusing (hope some CISPR/CENELEC member gets it). If we spill over the line (office, floor, building... whatever), emissions requirements are triggered. But within that line it's to be considered an intra-system (what's the system ? that's another good question to be settled) interference potential and the manufacturer should take care of it without need of enforcement because he has all the interest in making a product (system) that works properly and reliably. One last point: based on David Sterner's note, looks to me that North America has a pretty extensive Ethernet and-the-like network. I honestly don't know if the FCC has already enforced emission limits on LAN ports. Anyway, based on David's note looks like there are no complaits of interference with TV and telephones. And please note, this is the very bottom line of it. Emission limits should be intended to protect public services ... and physics works the same on both sides of the Atlantic... or not My personal opinion ... Paolo -Messaggio originale- Da: Ken Javor [SMTP:ken.ja...@emccompliance.com] Inviato:giovedì 7 settembre 2000 18.43 A: Paolo Roncone; 'eric.lif...@ni.com' Cc: 'emc-p...@ieee.org' Oggetto:Re: R: Conducted Emissions on Telecom Ports Although I don't work commercial EMC on a regular basis and I do not know over what frequency range the telecom port CE are controlled (I assume here 150 kHz - 30 MHz), I believe that there is a mistaken premise inherent in the comments to which I am responding. The purpose of controlling common mode CE on any port is not to protect equipment at the other end of the cable, or other co-sited cables, but rather to control radiated emissions in a frequency range in which CE are easier to measure than RE. In turn, the purpose of controlling RE is to protect broadcast radio reception. -- From: Paolo Roncone paolo.ronc...@compuprint.it To: 'eric.lif...@ni.com' eric.lif...@ni.com Cc: 'emc-p...@ieee.org' emc-p...@ieee.org Subject: R: Conducted Emissions on Telecom Ports Date: Thu, Sep 7, 2000, 9:45 AM 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 --- 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
RE: R: Conducted Emissions on Telecom Ports
Actually it's to reduce interference to one's own equipment, (if it emits it - it's also susceptible to it). It also has the effect of reducing interference to other near by equipment. Michael Sundstrom Nokia Mobile Phones, PCC EMC Technician cube 4E : 390B phone: 972-374-1462 mobile: 817-917-5021 michael.sundst...@nokia.com amateur call: KB5UKT -Original Message- From: EXT Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Thursday, September 07, 2000 11:43 AM To: Paolo Roncone; 'eric.lif...@ni.com' Cc: 'emc-p...@ieee.org' Subject: Re: R: Conducted Emissions on Telecom Ports Although I don't work commercial EMC on a regular basis and I do not know over what frequency range the telecom port CE are controlled (I assume here 150 kHz - 30 MHz), I believe that there is a mistaken premise inherent in the comments to which I am responding. The purpose of controlling common mode CE on any port is not to protect equipment at the other end of the cable, or other co-sited cables, but rather to control radiated emissions in a frequency range in which CE are easier to measure than RE. In turn, the purpose of controlling RE is to protect broadcast radio reception. -- From: Paolo Roncone paolo.ronc...@compuprint.it To: 'eric.lif...@ni.com' eric.lif...@ni.com Cc: 'emc-p...@ieee.org' emc-p...@ieee.org Subject: R: Conducted Emissions on Telecom Ports Date: Thu, Sep 7, 2000, 9:45 AM 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
RE: R: Conducted Emissions on Telecom Ports
Has anyone seen problems with ethernet and conducted emissions? I have a home office with 4 PCs networked with ethernet running over UTP and I haven't seen much of a problem. Granted, the longest cable run I have is to a file server in the basement (about 10 meters) but both my AM radio and my shortwave set seem to work just fine. The only thing I remember picking up is 20MHz on the shortwave set. (Most 10Mbit ethernet devices use a 20MHz clock.) At work we have both 10 and 100Mbit ethernet (150-200 nodes) and the AM reception is really bad but I attribute that to the building (big steel and brick box) more than noise as reception improves as you get closer to a window. I haven't tried the shortwave at work being that shortwave reception is usually bad during the day anyway. As far as telephone lines are concerned my ears don't pick up much noise above 19kHz. I would think anything else would be covered by immunity standards. Steve -Original Message- From: Cortland Richmond [mailto:72146@compuserve.com] Sent: Thursday, September 07, 2000 11:01 AM To: Paolo Roncone; ieee pstc list Subject: Re: R: Conducted Emissions on Telecom Ports Paolo Roncone wrote: 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. I disagree. The purpose of emissions standards is to prevent interference. Some are to similar functions, some are to other media. There is no interface for interference at which point the manufacturer may say: Interference when you use this isn't our problem. We may say: Use shielded cable, or Put a ferrite on your cable, but we can't evade the physical fact that it is our own equipment which is the source of interference, and the cable is its antenna. It does not matter that we do not own the cable; if you plug it in and there is interference, it is up to the people who made the equipment to see the interference reduced. There is no transfer of ownership for radio waves. Granted, to call a LAN cable telecommunications is a clumsy construction of the regulation. But those who grasp at that straw to save a few currency units will find themselves later regretting that they have done so. If you are beaten and robbed for a display of wealth, it is no use protesting that the money was counterfeit. Cortland Richmond (I speak for myself alone and not for my employer) == Original Message Follows Date: 07-Sep-00 07:48:16 MsgID: 1072-46656 ToID: 72146,373 From: Paolo Roncone INTERNET:paolo.ronc...@compuprint.it Subj: R: Conducted Emissions on Telecom Ports Chrg: $0.00 Imp: Norm Sens: StdReceipt: NoParts: 1 From: Paolo Roncone paolo.ronc...@compuprint.it Subject: R: Conducted Emissions on Telecom Ports List-Post: emc-pstc@listserv.ieee.org Date: Thu, 7 Sep 2000 16:45:03 +0200 Reply-To: Paolo Roncone paolo.ronc...@compuprint.it 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
Re: R: Conducted Emissions on Telecom Ports
Although I don't work commercial EMC on a regular basis and I do not know over what frequency range the telecom port CE are controlled (I assume here 150 kHz - 30 MHz), I believe that there is a mistaken premise inherent in the comments to which I am responding. The purpose of controlling common mode CE on any port is not to protect equipment at the other end of the cable, or other co-sited cables, but rather to control radiated emissions in a frequency range in which CE are easier to measure than RE. In turn, the purpose of controlling RE is to protect broadcast radio reception. -- From: Paolo Roncone paolo.ronc...@compuprint.it To: 'eric.lif...@ni.com' eric.lif...@ni.com Cc: 'emc-p...@ieee.org' emc-p...@ieee.org Subject: R: Conducted Emissions on Telecom Ports Date: Thu, Sep 7, 2000, 9:45 AM 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
Re: R: Conducted Emissions on Telecom Ports
Paolo Roncone wrote: 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. I disagree. The purpose of emissions standards is to prevent interference. Some are to similar functions, some are to other media. There is no interface for interference at which point the manufacturer may say: Interference when you use this isn't our problem. We may say: Use shielded cable, or Put a ferrite on your cable, but we can't evade the physical fact that it is our own equipment which is the source of interference, and the cable is its antenna. It does not matter that we do not own the cable; if you plug it in and there is interference, it is up to the people who made the equipment to see the interference reduced. There is no transfer of ownership for radio waves. Granted, to call a LAN cable telecommunications is a clumsy construction of the regulation. But those who grasp at that straw to save a few currency units will find themselves later regretting that they have done so. If you are beaten and robbed for a display of wealth, it is no use protesting that the money was counterfeit. Cortland Richmond (I speak for myself alone and not for my employer) == Original Message Follows Date: 07-Sep-00 07:48:16 MsgID: 1072-46656 ToID: 72146,373 From: Paolo Roncone INTERNET:paolo.ronc...@compuprint.it Subj: R: Conducted Emissions on Telecom Ports Chrg: $0.00 Imp: Norm Sens: StdReceipt: NoParts: 1 From: Paolo Roncone paolo.ronc...@compuprint.it Subject: R: Conducted Emissions on Telecom Ports List-Post: emc-pstc@listserv.ieee.org Date: Thu, 7 Sep 2000 16:45:03 +0200 Reply-To: Paolo Roncone paolo.ronc...@compuprint.it 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
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
