Abstract: A counting signal processing method for a fiber optic interferometric sensor including following steps is provided. An output intensity of the fiber optical interferometric sensor is converted into an electrical signal having the form V0+V1 cos ?(t). Then, the number of times N1 that the maximum peak values are greater than a first counting level S1 and the number of times N2 that the minimum peak values are smaller than a second counting level S2 within a specific period of time TC are counted. When the value of N1, N2 or (N1+N2) is greater than a threshold counting number Cth, a detectable induced signal occurring in a sensing area is inferred. Then, whether the detectable induced signals are caused by an intruder or otherwise is judged through an alarm identification logic, and an alarm device is triggered to send out an alarm according to the result of the judgment.

Abstract: A counting signal processing method for a fiber optic interferometric sensor including following steps is provided. An output intensity of the fiber optical interferometric sensor is converted into an electrical signal having the form V0+V1 cos ?(t). Then, the number of times N1 that the maximum peak values are greater than a first counting level S1 and the number of times N2 that the minimum peak values are smaller than a second counting level S2 within a specific period of time TC are counted. When the value of N1, N2 or (N1+N2) is greater than a threshold counting number Cth, a detectable induced signal occurring in a sensing area is inferred. Then, whether the detectable induced signals are caused by an intruder or otherwise is judged through an alarm identification logic, and an alarm device is triggered to send out an alarm according to the result of the judgment.

Abstract: A method of calibrating a three-axis magnetometer is provided. In accordance with the method, calibration is effected by first establishing a three-axis magnetic field simulator having a center position portion. Suitable measures are taken to substantially compensate for the earth's magnetic field at least at that center position portion. A three-axis magnetometer is then disposed in the magnetic field simulator and successively actuated in predetermined manner to generate a set of measured parameter values. The measured parameter values are normalized using a predetermined standard output factor, and a square pre-calibration matrix C is generated from the normalized measured parameter values. An inverse matrix operation is thereafter performed upon the pre-calibration matrix C to generate a square calibration matrix D having a plurality of coefficients respectively indicative of orthonormal compensation coefficients.