Abstract
In this paper, we propose a perimeter intrusion detection system which uses Michelson interferometers. This system has four defense zone and each zone employs a specified wavelength to detect intrusion. The goal of this paper is trying to find the thresholds at different weathers and situations. We preset three thresholds to decide whether the disturbance is intrusion or not. When the disturbance occurs and the detected signal meets the conditions for intrusion, the proposed algorithm triggers an alarm. In other words, if we want to reduce false alarm rate effectively, we just need to preset the right thresholds at first.