In 2011 a PLT EMC standard known as prEN 50561-1 was proposed by CENELEC. The proposed PLT standard was rejected by a majority of the National Standards Committees (NCs) of the EU countries who approve all new standards. Many NCs made comments to help improve the proposed standard, some comments questioned the very high radio pollution levels that would be permitted from PLT devices. Other comments would have helped to improve the test methodology. Usually in these situations the CENELEC committee preparing the proposed standard would take note and make changes that reflect the comments with the aim of achieving full consensus of all stakeholders.
A revised version of the PLT standard is about to be circulated, to be voted on by the NCs. For all intents and purposes we believe it is identical to the previous rejected standard. The valuable and helpful comments from the NCs have essentially been ignored. Representatives of PLT manufacturers dominate the CENELEC Working Group 11 (WG11) that wrote the proposed standard. PLT manufacturers have been aggressively lobbying members of the NCs to approve the standard as it would provide a legal basis for high PLT emission levels.
The EU Commission’s EMC advisor who is responsible for ensuring that all EU EMC standards comply with the EMC Directive has stated that the proposed PLT standard does not meet the Essential Requirements of the EMC Directive and notified CENELEC. However, CENELEC has decided to ignore the advice of the EU EMC advisor and continue with putting the proposed PLT standard out for voting by the NCs.
Should prEN 50561-1 be voted through by the National Committees it risks meaning that manufacturers of virtually any new device or product will want to use the very high radio pollution levels allowed by prEN 50561-1, claiming it as a precedent. An example case being the invertors used to connect solar cells to the grid where a proposed standard will
allow pollution levels similar to PLT but at all frequencies so no amateur band notches (a “notch” is a range of frequencies where the transmit power of the PLT device is reduced). Other products that could take advantage of this precedent include LED lighting.
In effect, the proposed PLT standard will make the provisions of the EMC Directive irrelevant. It’s not just HF but higher radio frequencies too are at risk from what will be legally sanctioned pollution. Wireline services could also become victims, new high speed DSL technologies such as G.fast could also have issues due to PLT pollution being coupled from power cables to phone cables.
There is only a very short time window to take action to prevent what will be an EMC disaster, many National Committees will vote early, due to the summer vacations. It is absolutely critical that anyone who values unpolluted radio spectrum urgently takes the following actions;
- Contact your national amateur radio society and ask what they are doing.
- Find out who is on your NC, contact them and explain the situation, it is important that they understand that the proposed PLT standard sets a precedent and its approval could lead to widespread spectrum pollution.
- Get the word out, forward this statement to your local message boards and radio clubs.
- When you have a QSO ask other European amateurs if they have heard about this issue.
There is a great deal of “disinformation” being spread by PLT lobbyists, some of the statements that have been made are clarified below;
PLT claim: Notching will protect the Amateur Bands
Reality: The depth of the notch will depend on how linear the power network is. Resonances in cabling resulting in high voltage levels of the PLT signals combined with non-linear components in devices such as switched mode power supplies, can lead to the notches “filling in” with “hash” type noise which is difficult to identify as PLT.
PLT claim: Ratification of EN50561-1 will protect the Amateur Bands
Reality: In the same way that PLT manufacturers now flout EN55022 they will be able to flout EN50561-1. It is just that the motivation will be less – at least until the next scheme for increasing data rate comes along. The only aspects of the new Standard that can be verified in the field by National Enforcement Agencies (such as OFCOM in the UK) are the maximum transmit level and the positions of the Notching Band edges. Within the new Standard the maximum transmit level is set at a higher level than today’s typical PLT transmit power levels, and the notched frequencies follow today’s practice as set by long-standing commercial considerations.
PLT claim: EN 50561-1 will control PLT emissions, as there is currently no PLT standard.
Reality: PLT devices are covered by EN 55022 which is the EMC standard for IT equipment — this has been confirmed by the EU Commission.
PLT claim: PLT cannot work at EN 55022 levels.
Reality: PLT devices can work at EN 55022 levels in most situations. Running at high power ensures PLT works in the remaining 1% of “difficult” situations. Mesh networking can address almost all of these difficult situations. High levels of pollution could result in “spectrum cleansing” where other spectrum users abandon spectrum to PLT due to PLT
PLT claim: Dynamic notching will protect the broadcast bands.
Reality: Dynamic notching was committed to be implemented in Quarter 3 of 2010 by PLT manufacturers to PA Consulting. PA Consulting was researching PLT on behalf of the Ofcom (UK regulator). This failure to demonstrate dynamic notching in production units could mean that it doesn’t actually work in the real world. This may be confirmed by the fact that there is no requirement in EN50561-1 that dynamic notching work in the presence of any interference (PLT for example).
PLT claim: Power control will reduce PLT pollution levels.
Reality: Power control was committed to be implemented in Quarter 2 of 2010 by PLT manufacturers to PA Consulting which was researching PLT on behalf of the Ofcom (UK regulator). This function has yet to be seen in production devices. PA consulting based its conclusions and recommendations on this commitment and the failure to deliver on this commitment makes a significant difference in the report’s conclusions.
http://stakeholders.ofcom.org.uk/binaries/research/technology-research/pltreport.pdf Page 57
The power control requirement in EN50561-1 is specified using an unrealistic test situation.
Produced by the EMC Committee of RSGB 25 July 2012.
For more information contact the EMCC via the EMC pages of the RSGB website http://www.rsgb.org/emc/