INTRUSION DETECTION ALGORITHM WITH WIND REJECTION HEURISTIC

A method is provided for analyzing a monitoring signal from a sensing system to determine an alarm condition, where the monitoring signal is provided as a stream of digital values which are analyzed using a frequency-based transform to generate a set of transform coefficients which are compared to a set of envelope coefficients. The sensitivity of the analysis is automatically controlled to accommodate environmental noise on the fiber by increasing the envelope coefficients to make the analysis less sensitive at each cycle by adopting the larger value from the comparison and by decaying the envelope coefficients at each cycle over time to a smaller value down to a floor value.