Fecha de publicación: 24/04/1991 Fuente: Wipo "Sensorization" In a defective sensor detection system for sensor arrays where signal response from a sensor is independent of sensor position in the array, the system is arranged to determine a mean square signal for each sensor and a system mean from these mean square signals, and to compare the system mean with each sensor mean square signal in turn, a differential above a pre-determined threshold being said to determine a defective or dead sensor. The system mean may be continuously re-determined. The sensors may be pyroelectric.