Lessons learned from MARECS and ECS EMC system tests

The advantages to spacecraft EMC control of comparing cable-coupled emission levels, measured by test probes mounted on the cable harnesses of MARECS and ECS with predictions obtained by SEMCAP modelling are shown. The use of simple tests and deductions to investigate discrepancies is advocated. The MARECS-ECS experience enabled common resistance coupling to be determined and showed that misleading effects of high background emissions were probably due to Earth loops in the test configuration. It highlighted difficulties in interpreting measurements made by photographic recording of spectrum analyzer displays, and underlined the logical implications of the variability of the bundle-shielding effect on the EMC validation of sister spacecraft.