Patent ID: 7375817

Claim:
A counting signal processing method for a fiber optic interferometric sensor suitable for processing an output intensity of a fiber optic interferometric sensor, the counting signal processing method comprising the steps of: converting the output intensity into an electrical signal having the form V 0 +V 1 cos ψ(t), wherein V 0 is the DC value of the electrical signal and V 1 is the amplitude of the electrical signal; counting the number of times N 1 of maximum peak values higher than a first counting level S 1 and the number of times N 2 of minimum peak values lower than a second counting level S 2 within a specific time period T C ; when the value of (N 1 +N 2 ), N 2 or N 1 is greater than a threshold counting number C th , judging a detectable induced signal has occurred within a sensing area of the fiber optic interferometric sensor; and judging if the detectable induced signals are caused by an intruder using an alarm identification logic and controlling an alarm apparatus to issue an alarm signal according to result of the judgment.