CENELEC ETSI JWG on network EMC

1
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.

2
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.

3
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.

4
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.

5
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.

6
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.

7
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

8
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.

9
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.

10
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 common-mode current
  limit to field values?
• NB 30?

11
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
  non-harmonised 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.

12
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.

13
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.

14
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.