Conformity Magazine - July 2008 - (Page 24)

Measurements are currently being carried out to assess whether the pass/fail criteria produce similar results to those of CISPR 16-1-4 and IEC 61000-4-3 to determine if chambers that do meet the different acceptance criteria in these standards will also meet the newly introduced acceptance criteion in the future IEC 61000-4-22. The proposal is quite different and may require some comparisons with the methods called out in the established standards CISPR 16-1-4 and IEC 61000-4-3 to gain credibility. Now that we have introduced the methods of the CISPR 16 standards series and also IEC 61000-4-20, 21 and 22, we can introduce the proposed replacement for CISPR 13 and 22 that will be called CISPR 32: “EMC – Multimedia Equipment – Radio disturbance - characteristics - Limits and methods of measurement.” The document has been prepared by CISPR/I and is based on the current best practices for EMC measurements, rather than being based directly on those standards it is replacing. CISPR/I also states that the new standard has been prepared in accordance with the principle of equivalent protection of the radio spectrum rather than strict equivalence of test procedures and results and, as a consequence, the reader familiar with CISPR 13 and CISPR 22 may not find all of the tests described in those two documents carried forward to CISPR 32. One of the interesting points to note for anechoic chambers is the introduction of limitations in the size of the equipment that can be tested for a given distance. The maximum EUT sizes at 3m, 5m and 10m distances are respectively 1.5m, 2.5m and 5m. By restricting the EUT size per measurement distance, the anechoic chamber designs will become less diverse. However, it is unclear how chambers that already test EUTs beyond the proposed maximum dimensions will fit into this concept. The importance of this new document is that it is introducing the notion of alternative methods. We have previously discussed the future standard IEC 61000-4-22, introducing an alternative chamber verification method to the one described in CISPR 16-1-4, and CISPR 32 will allow this method to co-exist with TEM cell (IEC 61000-4-21) and mode-stirred/ reverberation chamber (IEC 61000-4-20) requirements as well as CISPR 16-1-4 SAC requirements. Of course, each method has its own well known advantages. GTEMs are very practical for small devices with simple cable setup and their correlation to OATS has been accepted by the FCC, although not worldwide. On the other hand, mode-stirred chambers lack directivity information, but provide significant improvement of emissions testing efficiency by avoiding cable manipulations and FARs simplify measurement setup. Some see this as technically unsound because there is not enough evidence so far that the methods provide equivalent protection while determining different measurements. As a result, there is still no consensus that the inclusion of different test methods can be a way forward for the industry. At the moment, the new standard is scheduled for publication in 2010. After its publication, it was determined that either CISPR 22 and CISPR 13 or CISPR 32 can be used for product testing until 2015. Conclusions The CISPR 16 basic standard series has been significantly revised and amended in recent years to accommodate new measurement methods and the evolution towards higher frequencies. One of these parts, CISPR 16-1-4, now includes chamber validation techniques below and above 1GHz that impact the design of anechoic chambers today. Meanwhile, another part, CISPR 16-2-3, is extending measurement methods above 1GHz that are introducing new challenges. CISPR subcommittees are trying to harmonize these methods between basic and product standards, such that the CISPR 16 standards series can become the single reference for test methods and chamber validation processes. However, with alternative methods such as TEM cell, FAR and mode-stirred chambers being proposed by the draft CISPR 32 standard, a better understanding and further investigation of the implications of alternative test methods in a single standard is required. Martin Wiles is a Senior RF Engineer at ETS‑Lindgren, and can be reached by e‑mail at martin.wiles@ets‑lindgren.com. The author would like to thank Mr. Werner Schaefer of CISCO Systems (USA) and Mr. Martin Alexander of NPL (UK) for their highly valued critical review of this article. Both are CISPR/A experts, and have made significant contributions to the development and progress of CISPR 16 over the last ten years. Figure 11: IEC 61000-4-22 FAR proposed volumetric method 2 Conformity JULy 2008

Table of Contents Feed for the Digital Edition of Conformity Magazine - July 2008

Conformity Magazine - July 2008 Contents Editor's Note FCC Adopts 6 Million Dollars in DTV Enforcement Orders Commission Enforcement Bureau Adopts V-Chip Consent Decree FDA Seeks 2 Million Dollars from Medical Device Manufacturer FDA Answers Questions About CFLs and UV Radiation EPA Issues Energy Star Specs for TV, Video Boxes Canada Unveils Sweeping Product Safety Legislation How the Evolution of CISPR Standards Continues to Shape the Requirements for Anechoic Chambers ESD Open Forum Reach Compliance for Non-EU Article Manufacturers The iNARTE Informer Preamplifier Considerations for Emission Measurement Systems Effective Shielding in Medical Electronics Applications Product News Focus On...Power Components Buyer's Guide Updated Standards List for the EU's ATEX Directive EOS/ESD Symposium Set for September CPSC Actions in the News Researchers Work to Develop Non-Flammable Batteries Safety Link Launches Redesigned, Enhanced Web Site IEC Standards Update UL Standards Update Product Reviews Telcordia Standards Update From Our "You Can't Make This Stuff Up" Department Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - July 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.