Correlation of timing jitter and the re-emission spectrum in radiated immunity testing of digital hardware

The emission spectrum of digital hardware under the influence of an external threat field contains information about the interaction of the threat energy with the digital signals in the system. We present measurements showing how the characteristics of the reemission spectrum from a simple circuit may be correlated with variations in the timings of logic transitions within the circuit. This provides a direct link between the re-emission spectrum and dynamic failures in digital hardware and may therefore form the basis of an immunity measurement or diagnostic technique for digital equipment.