Meeting EN55022:1997 conducted emissions does not protect the product
at the other end of the cabling. ANSI/IEEE 802.x and ISO/IEC 8803.x
physical layer definitions protect the other unit of a two-point link.
Compatibility testing performed by manufacturers assures both
interoperability and immunity from damage and bit errors.
1) Violating 802.x/8802.x to meet EN55022:1997 would reduce
interoperability and degrade performance. Passive filters can
introduce cable length sensitivities due to unbalanced reflections;
i.e. the link dies at specific cable lengths.
2) LAN transmission is digital and inherently immune to frequencies
below 100MHz. LAN packets incorporate error detection at the LINK
level, and more error detection at higher levels.
The best argument for conducted-emission rules is UTP parallelling
telephone modem cabling. Radiated emissions from the LAN cabling can
couple and potentially cause bit-errors in the modem data; and as you
pointed out, measuring RF radiation at these low frequencies (and
levels) is not practical.
I agree STP does not eliminate conducted emissions through the shield,
but shielding passes EN55022:1997 and is preferable to waiting until
CENELEC rescinds the requirement.
David
______________________________ Reply Separator
_________________________________
Subject: Re: R: Conducted Emissions on Telecom Ports
Author: "Ken Javor" <SMTP:ken.ja...@emccompliance.com> at ADEMCONET
List-Post: emc-pstc@listserv.ieee.org
Date: 9/7/2000 12:43 PM
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,
>> 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>
>> > >
>> > > -------------------------------------------
>
>
>
>
>
>
>
>
>
>
> -------------------------------------------
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