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Thales Uses EMC Simulation To Reduce Testing Costs

Thales Technical Unit Control and Display Systems (CDS) uses electromagnetic compatibility (EMC) simulation to reduce testing costs on each new cockpit instrument. EMC is a major design challenge in cockpit instruments because they have a clear face which makes them difficult to shield. FLO/EMC electromagnetic simulation software from Flomerics enables Thales engineers to evaluate its products’ radiated emissions and susceptibility during the early design stages. “We use FLO/EMC to identify and fix EMC problems prior to the prototype stage, usually by improving the shielding,” said Julien Blanc, EMC specialist for Thales CDS. “As a result, this eliminates the need for late-stage design changes which in turn saves money by avoiding the need for modification of prototypes and additional testing.”

Thales is a leading international electronics and systems group that employs 60,000 people in 50 countries. Thales makes a wide range of cockpit and display systems for military and commercial aircraft. EMC is usually a major concern in the design of these systems. For example, engineers need to ensure that emissions from the display do not interfere with radio communications or radar-based collision detection systems. In the past, these concerns were addressed by building prototypes and testing them for EMC compliance. This often required expensive fixes on the existing design. In any case, the prototype had to be modified or re-built from scratch and the testing process had to be repeated. This was expensive and in some cases had an impact on the product launch date.

To improve the design process, Thales evaluated several different electromagnetic simulation methods. “We evaluated the major calculation methods and the leading software packages,” Blanc said. “We selected FLO/EMC because its predictions consistently matched our physical testing results and it is easy to use.” For example, in a recent experimental study, FLO/EMC predicted that radiated emissions at 160 MHz would be 33 dBmV/m in the far field and 95 dBmV in the near field. Actual measurements were 35 dBmV/m in the far field and 92 dBmV in the near field. FLO/EMC uses the Transmission Line Matrix (TLM) method for solving Maxwell’s equations, which solves for all frequencies of interest in a single calculation and therefore captures the full broadband response of the system in one simulation cycle.

In a recent application, calculated resonant frequencies for a cockpit instrument perfectly matched the test results for the same polarization. This insight quickly led to the design change of putting conductive material on vertical slits in the side cover of the cockpit instrument. Re-running the simulation showed that this solved the problem. The result was that the very first prototype met EMC specifications. “We have used FLO/EMC to simulate seven recent products and in each case we have found and fixed EMC problems in the qualification stage,” Blanc said. “Fixing problems in the early stages of the project is much less expensive because it avoids the need for building and testing additional prototypes to evaluate potential fixes.”

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