Enhancing EMC Compliance Testing with a Versatile EMI Receiver

1. Introduction
2. Scanning the Regulatory Environment
3. Comparing Compliance and Pre-compliance Testing
4. Understanding the Value of EMI Testing
5. Examining the MXE EMI Receiver
6. Summary
7. Related Information

On the road from idea to product launch, numerous obstacles can cause a company to miss a window of opportunity in the marketplace. For new electrical and electronic products, one of the most serious obstacles can be electromagnetic compliance (EMC), which is subject to government regulation in most countries. Products must pass full compliance testing for every country in which they will be sold.

Because a final-article product must be checked, testing usually happens late in the development process. A failed test causes delays while time is spent finding and fixing problems, and then restarting the entire compliance-testing process. To help ensure success on the first try, many companies are revising their development process to include pre-compliance testing of electromagnetic interference (EMI). A useful best practice is to perform these checks at multiple stages: breadboard, lab prototype, production prototype and pilot run.

The Agilent N9038A MXE EMI receiver is designed for two groups: independent laboratories that perform compliance testing and companies with in-house labs that self-certify. More than just an EMI receiver, the MXE is an Agilent X-Series signal analyzer that runs a variety of measurement applications. As a result, the MXE complements the knowledge of test-lab engineers with capabilities that will help them show designers what's really happening inside their products. Product developers can use an Agilent X-Series signal analyzer equipped with the same EMC measurement application used in the MXE to perform pre-compliance measurements and then enter compliance testing with greater confidence.

The applicable agencies and regulations vary by country or region. For example, products sold in Europe must satisfy the European Norms (ENs), which are based on recommendations from the Comité International Spcial des Perturbations Radioélectriques (CISPR). This "special international committee on radio interference" was founded in 1934 and is part of the International Electrotechnical Commission (IEC). Regulatory agencies in many other regions use CISPR recommendations when enacting local requirements.

CISPR 16-1-1 is the recommendation specific to measurement receivers used for EMI compliance testing. It has been revised to include the use of commercial spectrum or signal analyzers for some EN tests. The analyzer must include the proper types of signal detectors, provide the necessary measurement bandwidths, and be capable of reaching the required input sensitivity. The MXE is fully compliant with CISPR 16-1-1 2010 and exceeds CISPR requirements with ±0.78 dB measurement accuracy. It also offers excellent input sensitivity—a key measure of receiver performance—with a displayed average noise level (DANL) of –163 dBm at 1 GHz.

Full compliance testing is typically performed at an accredited test lab—independent or in-house—staffed by trained engineers and technicians. The facility must include a qualified open-area test site (outdoor) or semi-anechoic chamber (indoor) as well as an antenna tower, a turntable and a receiver that complies with CISPR 16-1-1. As a result, these facilities are quite expensive and the cost of compliance testing is many times that of pre-compliance testing.

In pre-compliance testing, a manufacturer's engineers perform preliminary assessments in accordance with the relevant standards. Although the measurements provide an approximation of expected EMI performance, they offer meaningful reassurance regarding the likelihood of successful compliance testing.

EMI testing typically addresses both aspects of compliance: conducted and radiated emissions. Conducted emissions are unwanted signals that appear on the AC power line connected to the equipment under test (EUT). Radiated emissions occur as high-frequency signals that are broadcast into the surrounding air by the EUT.

Both types of emissions are becoming more prevalent as microprocessor clock speeds extend into the gigahertz range. Consequently, signal analyzers that measure into the radio frequency (RF) and microwave ranges are useful tools, especially when equipped with an EMI pre-compliance measurement application.

For test engineers, the MXE offers enhanced accuracy, repeatability and versatility. One of its key capabilities is seamless shifting between the EMI-receiver and spectrum-analyzer modes. This gives labs the flexibility to confidently test new products and new types of products. It also enables new services such as consulting, supported by the MXE's built-in EMI diagnostic tools.

The included EMC measurement application enables easy signal identification with signal traces, measurement lists, meters and search functionality. Another useful capability is the strip-chart display, which enables tracking and evaluation of signal trends over time (Figure 1).

The ability to seamlessly switch to spectrum analyzer mode using signal frequency coupling enables closer examination of signal details with tools such as marker functions, span zoom, zone span and spectrogram displays. In this mode, the MXE can also run Agilent X-Series measurement applications such as noise figure, phase noise and analog demodulation (as available). By enhancing the analysis of noncompliant emissions, these capabilities enable EMI test engineers and consultants to evaluate signal details and deliver new insights about the products they test.

Agilent solution partners already support the MXE in EMC applications: ETS-Lindgren, TDK RF Solutions, Inc. and TOYO Corp. can help our customers create new labs or enhance existing facilities. These solution partners can also provide turnkey solutions for systems, chambers, towers, antennas and more—including training, installation and support—all through a single point of contact.

Compliance testing becomes faster and simpler with the MXE and its built-in EMI testing routines. Labs can confidently handle any new product—or new type of product—that is brought in for compliance testing. For the organization, the flexibility of the MXE also opens the door to new service offerings.

Product developers can leverage the same EMC measurement application with an X-Series signal analyzer to quickly perform informative pre-compliance measurements and then get back to the task of completing the product. For the organization, this can result in a greater likelihood of meeting the window of opportunity for the new product.

Agilent Technologies Inc. (NYSE: A) is the world's premier measurement company and a technology leader in chemical analysis, life sciences, electronics and communications. The company's 18,500 employees serve customers in more than 100 countries. Agilent had net revenues of $5.4 billion in fiscal 2010. Information about Agilent is available at www.agilent.com.