Wednesday, December 18, 2002

Electromagnetic Interference

As electronics become faster and smaller, they become more prone to electromagnetic (EM) interference. At the same time, the proliferation of wireless connections, everything from mobile phones to 802.11/Wi-Fi networks, and other electronic devices is increasing the number potential interference sources. Though EM interference's potential for causing malfunctions and accidents is bad enough, it could be even more devastating if criminals, terrorists, or other malicious parties use it to deliberately disrupt or destroy electronic systems. In Japan in 1998, a group of criminals instructed a pachinko machine (a mixture between slot machine and pinball) to dispense cash using a high energy radio-frequency device, while in Russia a thief robbed a jewelry store by using a similar device to bypass the alarm. Such interference-generating gadgets can be built from off-the-shelf components like microwave tubes, banks of capacitors (for building up high voltages) and antennas (for directing and concentrating the transmitted energy). Depending on the power and patterns of the emissions, the damage can range from temporary hiccups to total circuit burnout. Militaries around the world have started to integrate the potential threat of EM interference into the design of new devices. A few simple design changes to protect from EM interference could include adding more space between etched lines on a circuit board and more insulation around wires and critical circuits -- this has the secondary benefit of reducing the device's own EM emissions. The design changes proposed here might slightly increase the overall size of the device, but smaller is not always better in electronics.

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