Upset thresholds of various systems as measured by the R²SPG technique

The upset thresholds of five systems were determined using the Repetitive Random Square-wave Pulse Generator (R²SPG) technique. These systems included an AT class personal computer, a large digitally controlled communication system, a data display sub-system for a communication system, two radars and a point defense system. If the upset threshold was within the limits of the test program and the capabilities of the R²SPG, significant upsets generally required 3 to 10 Amperes, even in unhardened systems. “Snow” on visual displays occurred at smaller currents. As expected, some of the more modern systems had lower thresholds and more frequent upsets than older systems with less digital circuitry. However, some digital systems were found to be immune to upset of damage up to very high levels. None of the systems were damaged by the test. This tentatively confirms the statement that “upset occurs before damage.”