Monday, July 12, 2010

EN 55013, QP vs RMS

An analog TV showing noise, on a channel with ...Image via Wikipedia
The EU Commission is holding off publication of the CENELEC standard, EN 55013: 2009, in the official journal, as a result of a negative opinion of the EMC CENELEC consultant.

Publication in the official journal is a required step for any standard to be considered a harmonized standard, for the purpose of conformity assessment, under new approach directives, in this case, the European EMC directive.

The published harmonized version, as of March 1, 2009, is EN 55013: 2001 +A2 2006.

The point of contention with EN 55013: 2009, is the introduction of an RMS average limit.

Traditionally, measurements are based on a Quasi Peak limit, and made using a “Quasi Peak” detector. Legitimate debates continue regarding the suitability of the specified Quasi Peak detector based system for high frequency measurements, or for gauging interference caused to modern digital systems. See Practical Paper “The Quasi-Peak Detector” By Edwin L. Bronaugh for more about the QP detector.

The consultant points out that the proposed RMS average limit offers a “major relaxation of the limits, up to 20dB”, and contends that protection of analog services will be significantly reduced.

The question that the commission is looking to answer now is what effect this limit change will have on equipment using analog technology, as it is assumed that newer digital equipment has a higher tolerance for increased interference levels.

The commission is seeking the EMC working group delegate’s input by August 23, 2010 on whether or not the new standard adequately protects the essential requirements of the EMC directive.

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