Crew Quarters (CQ) and Electromagnetic Interference (EMI) Measurement Facility combined impedance study

Abstract

This report documents an investigation into observed anomalous behavior associated with conducted susceptibility testing of Crew Quarters (CQ) hardware in the Johnson Space Center (JSC) Electromagnetic Interference (EMI) Measurement Facility, and the work accomplished to identify the source of the observed behavior. Investigation led to the conclusion that the hardware power input impedance was interacting with the facility power impedance leading to instability at the observed frequencies of susceptibility. Testing performed in other facilities did not demonstrate this same behavior, pointing back to the EMI Measurement Facility power as the location of the potential root cause. Ultimately, a Line Impedance Simulation Network (LISN) emulating the Station power bus impedance was inserted into the power circuit, and the anomalous behavior was eliminated from the measurements.