Reduction of nuisance alarms in exterior sensors using ESP

Rain has always been a big problem for outdoor intrusion systems, making it necessary to choose between nuisance alarms and poor detection. The author reports on extensive environmental tests and describes a signal processing technique called ESP (enhanced signature processing). This effort produced a detection improvement of approximately 10 dB while suppressing the effects of rain-induced noise by an additional 12 dB. The evaluation technique used to investigate rain characteristics utilized a video tape recorder in which various Doppler signals from a K-band monostatic sensor were recorded on the audio channel of a video tape recorder while the actual rainy scene was recorded as video. The recorded signals were processed in the laboratory, and appropriate circuitry was developed utilizing the recorded information during the design phase