Method for detecting an object motion
The invention relates to security methods, while protecting against false activations, and it relates to a method for detecting a motion of objects that utilizes a passive infrared sensor. The invention may be used for security alarm systems. A method for detecting an object motion is proposed, the method comprising: detecting a motion within sensitivity areas of at least two pyrosensors and generating a signal from said pyrosensors.
1 . A method for detecting an object motion, the method comprising:
detecting a motion within sensitivity areas of at least two pyrosensors and generating a signal from the at least two pyrosensors, wherein the at least two pyrosensors are arranged one on top of another,
then, measuring an intensity of the signal by determining a change rate of the signal within a measurement period of 150 ms at most from each pyrosensor of the at least two pyrosensors, particularly, building a function of the signal change rate at a number of measurements of at least 32 for said measurement period,
comparing the measurement data of a derived function curve to thresholds, if the thresholds are exceeded by at least 3%, comparing forms of the curves from the at least two pyrosensors by means of a Pearson correlation coefficient,
if a similarity extent between the forms of the signals is lower than a reference value, dividing the signals into at least 8 spectral components in a form of sinusoidal functions and comparing them between each other and to the reference values by:
establishing a similarity percentage between each spectral component of each signal and the reference ones by determining a common fraction of area of two spectral distributions, wherein one distribution is a preset reference one, while another one is received from the signal; comparing the determined similarity percentage to the threshold;
determining a similarity percentage between each spectral component of the signals by determining a common fraction of area of two spectral distributions, wherein one distribution belongs to the signal from one pyrosensor of the at least two pyrosensors, while another one is received from the signal of another pyrosensor of the at least two pyrosensors; comparing the determined similarity percentage to the thresholds, and
if the similarity percentage is at least 25%, forming an object motion detection signal.
2 . The method for detecting the object motion of claim 1 , wherein the measurement period is between 50 and 150 ms from each pyrosensor of the at least two pyrosensors.
3 . The method for detecting the object motion of claim 1 , wherein the signal change rate function is built at the number of measurements of 64.