On the detection of random broadband signals

One of the most critical problems in immunity testing is to detect the malfunctions of the equipment under test (EUT) when the susceptibility signals are injected into it. In most EMC specifications it is left to the test operator to decide whether the EUT is susceptible on the basis of examination of qualitative output parameters; even if quantitative data is available the pass/fail decision is still based upon purely deterministic considerations, which do not take into account possible degradations due to many factors such as test equipment random performance characteristics, equipment aging and the parameter spread of electronic components used in manufacturing processes. Statistical evaluations may be necessary to find out a suitable solution to this problem especially in the case of safety critical equipment and systems.