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EMC & EMI Pre-compliance Testing

What is EMC and why is it important?

Electromagnetic compatibility (EMC) testing is a critical part of any product development journey. EMC is strictly regulated by development and production standards to ensure products’ safe operation next to other electronic devices. The fact is that all electronic devices emit electromagnetic waves while they operate. However, for some devices, it is an undesired byproduct. The emissions can come from many sources and can be strong enough to interfere with other electronic devices. Electromagnetic interference (EMI) is always an unwanted occurrence, whereas EMC is mandatory for all electronic products. EMC is especially important in areas where precise tasks are carried out or where even slight disturbances might cause serious consequences. The overall aim is to eliminate or reduce EMI below certain limits.

EMI: radiated & conducted emissions

EMI as an unwanted occurrence can be continuous, existing constantly in the background, or it can occur for a short period of time. When considering the way EMI is propagating from the source to the device affected by the noise, radiated and conducted emissions can be differentiated. Radiated emissions are emitted by a device, propagate over the air and can affect other devices. In comparison, conducted emissions propagate through electronic connections (e.g. cables) from one device to other directly connected devices.

EMC testing in the product development

As illustrated in the figure, pre-compliance and debugging tests should already be performed early in the development process in order to ensure that EMC standards are adhered to. Also, the possibility of having to redesign a product due to EMC testing failures shrinks. This contributes to meeting the development budget and time-to-market.

Basic EMI debugging process

In most cases, the development process turns out as a sequence of standard steps. Near-field measurements are used to localize the source of interference. After the noise source has been located, the behavior of the interference can be analyzed and corrective measures assessed. A final pre-compliance measurement is performed before going into the compliance stage. Each step requires continuous testing that can be performed by different types of test equipment. While pre-compliance, as well as debugging tests, are mostly done with the help of a spectrum analyzer respectively an oscilloscope, compliance tests are usually done with EMI receivers.  

Rohde & Schwarz is a high-tech company that thrives on innovation. To maintain its high quality standards, Rohde & Schwarz keeps almost the entire value chain within the company while the majority of products are developed in Germany. The Munich based technology group develops, produces and sells a wide range of electronic capital goods for industry and government customers with a focus on solutions that contribute to a safer and connected world.

16 Jan 2020, 9:45