March 2015

This article shows how electromagnetic simulation tools can be used to investigate effects of high-speed signals in cable harnesses in a vehicle: cross talk, radiation and interference with a receiving antenna. Results are presented for two types of digital sequences and compared with standards. Cable shielding is designed to be adequate without adding unnecessary weight.

Intentional RF transmitting devices seem to be everywhere. Smart phones, tablets and similar devices provide the ability for users to be connected to the internet any time, from any location using nearly any device. Other than the Boundary Waters Canoe Area Wilderness and the inner canyon of the Grand Canyon, it may be difficult to find any location without WiFi available.

Ethernet’s success in the marketplace is undeniable, and market-driven standardization has been instrumental in its success. It’s a cycle of synergistic innovation and market growth that has been spinning for decades. Ethernet has become entwined with almost every pattern and process of every-day life around the world. Whether a personal computer (PC) has a direct connection to a router or an indirect connection through a “Wi-Fi®” access point, it is highly likely that Ethernet is providing the connection to the Internet.

Sooner or later, anyone involved with EMI will be involved in troubleshooting an EMI problem, wherever it may surface. Most commonly, the problems will be uncovered during EMI testing, generally very late in the product design cycle, resulting in costly patches and schedule delays. It is best if preliminary EMI testing is done early in the design stage - EMI problems can be uncovered early enough that corrective action can be done in a timely fashion, ideally at the circuit board level. On the back end, EMI problems are often encountered in the field - perhaps because the environment is harsher than that expected by the regulatory agencies or because of an installation problem.

Up until now there’s been much emphasis on designing to make a product “idiot proof”. This has provided some benefit, but what Usability Engineering is reminding us is that it is the designers who are sometimes viewed as idiots by the users. It is the users who are the experts (in usability).