Emc Design, Emc Tests, And Emc Testing In Relation To Cell Phones

By Author: convurgency
Total Articles: 16
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Networked telecommunications equipment falls under the GR-1089 regulations set forth by the industry in the United States. These regulations are in line with worldwide standards. Both wireline and wireless EMC products fall under these guides as has been the case for over a quarter of a century. New technology has required six updates to these regulations, with the latest one being released in May 2011. The new document covers NEBS criteria for Central Offices (COs), Electronic Equipment Enclosures (EEEs) and huts, Outside Plant (OSP) at Controlled Environmental Vaults (CEVs) equipment uncontrolled structures like cabinets, and network devices existing in consumer locations.

The latest document adds more data on wireless applications in its own appendix for easy reference, revises EMI radiated and magnetic emissions in section 3 to remove testing for below 30 MHz, condenses and simplifies Lightning and Power Fault criteria (section 4), updates Steady-state power induction criteria (section 5) with latest and edited figures, adds the new lightning requirements for equipment at cell sites, and revises the requirements ...
... for testing compatibility of dc power ports.

Because the very nature of telecommunications networks and equipment it is very likely to be exposed to a number of sources of electromagnetic fields. What the GR-1089 attempts to do is to give builders, designers, and system testers guidelines that avoid damage and malfunction of this vital service and the hardware components that are part of it due to natural and man made sources of this energy. Some causes to be warded against include lightening, 50/60-Hz commercial power fault conditions, Electrostatic Discharge, Electrical Fast Transient, EMI, operation in the dc differences, and operation in steady-state induced voltage situations.

Additionally one must take care to follow the enclosed guidelines that keep this equipment from becoming fire or electrical safety hazards when exposed to severe lightening or power fault conditions. This means including data on safe voltage levels for intentionally applied power, electrochemical corrosion effects, grounding methods, and dc power sources for both wireline systems and wireless ones. Wireless systems can provide both fixed and mobile services while being installed along side wirebased telecommunications or information technology networking devices.

This is actually but one tool used by PCB engineers who search for RF leakage within systems that are either being designed or are in use. In many cases this is unintended by both system designer and consumer. High speed, power, or density systems that are complex have more of a chance of this happening then simpler systems, but in today's communication environment one typically has little choice in meeting consumer demand. Another tool used is EMxpert. This tool provides a way to visualize root sources of EMC and EMI problems as the are located. Instead of using a chamber and testing for individual factors, this allows for greater insights to how the complete design may fail without needing to delay for chamber redesigns between possible solutions to the failure are addressed.

Using newer devices to assist in testing can reduce time to market factors by finding emissions sources in internal circuit boards, cables, connectors, and other things that might increase levels to an undesirable extent. Using spatial can and graphing abilities can provide maps of emission sources and current loops, displayed in real time. This is the kind of new innovative products that the field can use to enhance testing and bring new products to the market faster. Looking at immunity and susceptibility issues the same tool can reveal how injected RF signals interact with the device to reveal problems with high amplitude currents and your design. The data can be stored for convent analysis between different current flows as well.

Common mode currents are a prime cause of EMI emissions. Identifying these at the unexpected locations where they commonly crop up, like at 1/O cable couplings or connectors, is vital to reducing emissions early on in the design stage. Because common mode currents are hard to predict and have many causes yet are a major source of radiation being able to measure these currents in prototypes under construction is extremely useful. Tools like EMxpert allow and create visual maps of differential mode currents that may be coupling int connectors leading to common mode radiation so you can address it as it develops.

Because this is such a useful tool, one you can use to test switching mode power supply circuits, component shielding, antenna function and more. By using both GR-1089 and EMxpert in conjunction those who work in this field can easily test new equipment in the telecommunications field for compliance and function.

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