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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.
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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.
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.
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.
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.
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.
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.
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
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.
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.
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?
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.
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.
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.
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.
