Transcript Document

CENELEC ETSI JWG on network EMC
The JWG was set up before Mandate
M313 was issued in order to ensure an
even-handed treatment by the Technical
Committees of CENELEC and ETSI in
drafting emission limits for networks.
Later, the task of producing deliverables
for Mandate M313 was assigned to the
JWG.
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Initial goals for the JWG
Define a network and technology neutral
emission reference limit.
Devise conversion methods from the
reference limit to network or technology
specific requirements which could be
formulated in product standards.
Define a field measurement method with
associated limits.
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Membership of the JWG
Membership of the JWG has been open
to all interested parties who wish to
attend.
Outside of members nominated by the
Technical Committees of CENELEC and
ETSI, participants from CEPT, the EBU,
NATO, amateur radio and other groups
have attended JWG meetings.
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Technical problem areas
 Existing limits are designed for narrowband
sources of disturbance; broadband sources
have greater interference potential.
 Total disagreement on appropriate limits.
 Network radiation properties not well
researched.
 Power line transmission and unbalance
characteristics not well documented in
frequency range 150 kHz to 30 MHz.
 How to deal with safety and emergency
services.
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Initial work activity
Apply theoretical conversions and
compare different measurement methods
and limits in harmonised standards to
check for coherence.
Devise theoretical conversions between
network or equipment limits and field
limits for the frequency range 150 kHz to
30 MHz.
Analyse the results available of field
measurements of network radiation.
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Network radiation compliance
At issue is the implementation of new
broadband services on existing networks;
network transmission and radiation
characteristics are constants in the
equation.
The only way available to control network
radiation is to control the level of the
signals and disturbances injected into the
network. This can only be done in
modem specifications.
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The vexed question of limits
Radio users and some administrations:
Tighten existing limits by 30 dB
Telecom suppliers and operators and
some administrations: Continue to apply
existing limits
PLC suppliers and operators: Relax
existing limits by 30 dB
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Agreed in the JWG
The text of a draft network emission
standard has been agreed.
Compliance with this standard can be
shown by a number of independent
methods.
Resolution of the limits issue and need
for field limits under 30 MHz subject of a
questionnaire to the NSOs.
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Compliance options:
 Application of an appropriate harmonised
product emission standard that covers network
radiation aspects. The network also must meet
specified cable standard(s).
 Compliance with the common-mode current
limit.
 Compliance with field limits measured at 3 m in
the frequency range 150 kHz to 30 MHz.
 Compliance with radiated limits measured from
aircraft.
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The Questionnaire
The NSOs are asked:
Is there a need to define a magnetic field
limit under 30 MHz?
If yes should this limit be based on:
Conversion of the reference commonmode current limit to field values?
NB 30?
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Remaining difficulties
It is not clear how the JWG can give special
consideration to safety and emergency services
as required in the Mandate.
 Some of these services are on frequencies
harmonised within the EU, some are on nonharmonised frequencies. The JWG is likely to
seek clarification as to exactly which services
are to be given special consideration.
 There is no agreement to date as to which
specific measurement method is suitable for
PLC modems.
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Timetable
 A questionnaire dealing with limits and the need
for a field measurement option for frequencies
under 30 MHz has been sent to the National
Committees and ETSI members. Background
information and a list of safety and emergency
services have been attached to the
questionnaire.
 A finalised draft emission standard should be
sent for formal comment in March.
 The deadline for replies is in February 2004.
 A prEN for vote should be circulated in Autumn
2004.
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Results of measurements of emission
Measurements of emissions from
networks have been made.
The results of most of these are not in
the public domain and are therefore of no
help to the development of standards.
To be of use to standardisation the
results of measurements must document
injected levels in terms which relate to
the measurement methods defined in
standards.
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Immunity for networks
Development of immunity standard(s)
has been given a low priority.
The general opinion is that the immunity
of the network is determined by the
immunity of the equipment connected to
the network and there is therefore no
need for harmonised immunity standards
for networks.
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