What is CISPR 32?
For a more complete version of this blog, see the article I wrote for Interference Technology at http://www.interferencetechnology.com/cispr-32-what-is-it-why-was-it-written-and-where-is-it-going/. The following is a summary of key parts of this article.
CISPR 32, “Electromagnetic compatibility of multimedia equipment – Emission requirements” was first published in 2012. This standard came about due to a major development in consumer electronics, the digital television receiver.
The CISPR is a special committee of the IEC. CISPR stands for the French words for the International Special Committee on Radio Interference. CISPR publishes a number of EMC standards used for a variety of product families. This article will discuss only a very small portion of the standards published by CISPR.
When digital television receivers were developed the manufacturers found that they now had two standards to deal with for emissions, whereas with analog television receivers they only had one CISPR standard. A digital television receiver has both a broadcast receiver and a computer in the same box. Hence, both CISPR 13 and CISPR 22 applied to the product. As the limits and test methods differed between the two standards each had to be addressed separately. Needless to say, this added time and cost to the qualification process. Managers don’t tend to look kindly on things that add time and cost to the development process, especially when they see no benefit. As a result, efforts began in CISPR to address this matter.
To create the new standards needed, CISPR/E (broadcast receiver standards) and CISPR/G (ITE standards) were merged in 2001, forming the new CISPR Subcommittee I (Electromagnetic compatibility of information technology equipment, multimedia equipment and receivers). CISPR/I initially had 4 working groups. WG1 was tasked with the maintenance and updating of CISPR 13 (emissions) and CISPR 20 (immunity) for broadcast receivers. WG3 was tasked with the maintenance and updating of CISPR 22 (emissions) and CISPR 24 (immunity) for ITE. WG2 was tasked with the creation of the new multimedia equipment emissions standard, CISPR 32 and WG4 was tasked with the creation of the new multimedia equipment immunity standard, CISPR 35. WG1 and WG3 were dissolved at the end of 2012 and any continuing work on the old standards was folded into WG2 for emissions and WG4 for immunity.
Writing the new standards was not simply a matter of merging two existing documents. It took CISPR/I 11 years to finally publish CISPR 32. CISPR 32, Edition 1.0 was published in January 2012.
CISPR 32:2012 (1st Edition)
While its structure is different, CISPR 32 more closely resembles CISPR 22 (ITE) than it does CISPR 13 (Broadcast receivers). The limits, for the most part, are those contained in CISPR 22. Power line and telecommunications port conducted emissions limits are specified over the same 150 kHz to 30 MHz range, measured using the same techniques and equipment as in CISPR 22 and using the same limits. Likewise, radiated emissions limits are specified over the same frequency range of 30 MHz to as high as 6 GHz, with the same measurement techniques as in CISPR 22 and, again, using the same limits. CISPR 32 also adds radiated emissions limits from FM receivers at the fundamental and harmonics of the local oscillator frequency. The first edition further changed from calling out specific conducted emissions requirements on telecommunications ports as called out in CISPR 22 to, instead, providing limits for “asymmetric mode conducted emissions” which are applicable to wired network ports, optical fiber ports with metallic shield or tension members and antenna ports. Additional limits are provided for “conducted differential voltage emissions” for TV broadcast receiver tuner ports with an accessible connector, RF modulator output ports and FM broadcast receiver tuner ports with an accessible connector. This final set of limits is only provided at class B levels.
Two corrigenda were issued for CISPR 32 shortly after it was published.
The first corrigenda issued for CISPR 32 made an editorial correction to the French version of the standard. The second corrigenda corrected the errors that had been introduced by the IEC Central Office when they created the published form of CISPR 32:2012. As a result, CISPR 32 had been amended twice by August 2012. When further additions were proposed for CISPR 32 they resulted in the 2nd Edition of the standard, rather than an amendment.
CISPR 32, 1st Edition, provided for performing radiated emissions testing at an Open Area Test Site (OATS), either with or without a weather protection cover, an RF semi-anechoic chamber or a Free Space OATS (FSOATS). Unlike CISPR 22, which provide guidance on testing of radiated emissions below 1000 MHz at distances other than 10 meters for certain class B devices, CISPR 32 explicitly provides limits at 3 meters, as well as limitations on the suitability of test sites chosen for these different measurement distances. It also limits the use of an FSOATS to testing at frequencies above 1 GHz.
CISPR 32:2015 (2nd Edition)
What was changed with the publication of CISPR 32, 2nd Edition, with it came out in March 2015? The 2nd Edition of CISPR 32 provides a number of clarifications, new test methods and guidance on testing additional product types.
CISPR 32, 2nd Edition, adds limits and other guidance for testing radiated emissions below 1 GHz in a Fully Anechoic Room (FAR). Limitations and clarifications for the use of a FAR for radiated emissions testing below 1 GHz are provided in Table A1.4 and include the limitation that this facility may only be used for testing table-top EUTs. The tables providing limits for radiated emissions were all amended to cover the different types of measurement facilities. Limits are now provided for an OATS/SAC at 10 or 3 meters and for a FAR at 10 or 3 meters, both for class A and class B equipment.
A new table, A.7, was added to provide requirements for outdoor units of home satellite receiving equipment. This table includes limits for radiated emissions over the frequency range of 30 MHz to 18 GHz, the only limits above 6 GHz in CISPR 32. A whole new annex, Annex H, was added as an informative annex to provide supporting information on the measurement of outdoor units of home satellite receiving systems.
Annex I was added as an informative annex to provide information on other test methods, such as the Gigahertz Transverse ElectroMagnetic (GTEM) chamber and a ReVerberation Chamber (RVC). Annex I points out that information on these two test facilities is provided for information purposes and that meeting the limits in Annex I does not constitute compliance with CISPR 32.
In addition, when CISPR 32, 2nd Edition, was published a number of the dated references in section 2 of the standard were updated, as well. New figures were added, definitions were updated and other changes made throughout the standard. These changes are far too numerous to detail in this article.
How do I know what has changed?
The IEC makes it easy to see what has changed when a new edition of a standard is published. For additional cost you can purchase the Redline Version of the standard which shows all the changes and additions in red ink. The IEC does facilitate multiple copy purchases by giving quantity discounts on the electronic versions. A 20 copy license, for example, may be purchased for the price of 4 individual copies. Plan your purchases accordingly.
What is coming in the future?
CISPR/I WG2 is looking at a number of potential updates and changes to CISPR 32 over the next number of years. CISPR/I/510/DC was published on June 26, 2015 based on issues discussed in the May 2015 meeting of CISPR/I WG2 and includes a number of items to be considered for future work on CISPR 32. During the meeting of CISPR SC I WG2 in Stresa, Italy on October 1 these possible areas for consideration were discussed. It is too early to speculate on when some of these changes may appear in CISPR 32, but consider that the stability date for CISPR 32 is 2018, so there shouldn’t be an amendment to the standard prior to that year.
Keep in mind that like all CISPR (for that matter, all IEC) documents, CISPR 32 is only so many words on paper. Unless and until a regulator adopts it into their national regulations it means nothing. For example, CISPR 32:2012 has been adopted in the EU as EN 55032:2012 and must be used in place of EN 55013 and/or EN 55022 for all products placed on the market in the EU (regardless of when first declared compliant with the EMC Directive) by March 5, 2017. As of the time of the writing of this blog, nothing has been said in the list of harmonized standards about EN 55032:2015, so we must wait and see about the new edition.
CISPR 32 is an important standard for manufacturers of multimedia equipment (including digital television receivers) and provides a unified approach for demonstrating a reasonable level of control of emissions from these products to product other users of the radio spectrum. Products already compliant with the requirements in CISPR 22 should see no impact on their design due to the switchover to CISPR 32 in the near future.