Conformity Magazine - December 2008 - (Page 33)

In the past few years, the measurement standards have changed to make these 10-meter weather-protected OATS meet the same technical requirements of the 10-meter SAC. That is, both venues must comply with the volumetric normalized site attenuation acceptance criteria in order to be used for final acceptance testing of products with national regulations for allowed radiated interference signals. Thus, the weather-protected standard OATS must meet the same demanding technical requirements without the benefit of excluding ambient signals, which complicate the measurement process through the addition of external signals to the internally generated signals from the product under test. Of course, the 10-meter SAC allows the testing organization to concentrate on only the internally generated signals, since the shielded room portion of the SAC blocks out the ambient signals (usually licensed broadcast signals such as FM radio, VHF Television, cell phone signals, and UHF television signals). In reviewing the alternatives, a 10-meter horizontal antenna distance is clearly the technically superior alternative for physical reasons, and for consistency with national regulations on allowed electromagnetic emission levels. A SAC makes the most efficient use of the 10-meter measurement distance because of the lack of ambient signals in the SAC. Daniel D. Hoolihan is an independent consultant, and can be reached at d.hoolihan@ieee.org. References 1. CBEMA/ESC5/77/29 – Limits and Methods of Measurement of Electromagnetic Emanations from Electronic Data Processing Equipment and Office Equipment; 20 May 1977. Paul, Clayton, Introduction to Electromagnetic Compatibility; John Wiley & Sons, Inc.; Second Edition, 2006. Garn, H.J., Zink, E., and Kremser, R., “Problems with Radiated Emission Testing at 3-meter distance according to CISPR 11 and CISPR 22,” 1993 IEEE International Symposium on EMC. 2. 3. FAST Link www.conformity.com/2450 Your online source for product & service providers that will help your business grow Connecting Buyers and Sellers Conformity Online Buyer’s Guide ® Testing and Certification | EMI/RFI Shielding | Passive Electronic Certification Education and Professional Training & Resources | Test, Measurement and Monitoring Equipment Cabinets, Racks & Enclosures | Chambers, Shielding and Accessories | plus more www.conformitydirectory.com DeCember 2008 Conformity 33 http://www.conformity.com/2450 http://www.conformitydirectory.com http://www.conformitydirectory.com

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

Conformity Magazine - December 2008 Contents Editor's Note FCC Warns Regulatory Fee Payers About Potential "Phishing" Commission Prowls the Web to Enforce Its Regulations First DTV Rollout Initiated in Wilmington, NC New Standards List Released for the EU's Directive on the Safety of Toys ESD Association Call for Papers ESDA. JEDEC Announce Standards Development Cooperation Commission Releases Data on Local Telephone Competition The Future of ESD Testing ESD Open Forum Emerging Issues in Standards: China RoHS: One Year and Counting Challenges in Testing: Revisiting 10-Meter and 3-Meter Radiated Emission Measurements Design Fundamentals: Meeting the Shielding Challenges of Injection-Molded Plastics Focus On...Microwave Absorbers Buyer's Guide FDA Recalls Automated External Defibrillators FDA Revises Guidance on Medical Device Tracking Guidance Document Safety of Passive Implants Released FDA Offers Guidance on Marketing Diagnostic Ultrasound Systems EU Commission Issues Correction on Machinery Directive Standards Other CPSC Actions in the News Product Reviews IEC Standards Update UL Standards Update Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - December 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.