KR20040011691A - Intrusion sensing and intrusion object discriminating method using an optical fiber - Google Patents

Abstract

PURPOSE: A method for sensing an invasion and a method for classifying an invading object by using an optical fiber are provided, which is applied to various industry fields by identifying the invading object into a person or vehicle. CONSTITUTION: A method for sensing an invasion by using an optical fiber includes: a first step(S1) of converting the signal sensed at the monitoring system into a digital signal; and a second step(S10) of determining whether the invasion is occurred or not in response to the summation value by summing(S5-S9) all of the sample data while sliding the time window for the converted digital signal sample data.

Description

Intrusion sensing and intrusion object discriminating method using an optical fiber}

The present invention relates to a method for intrusion detection and intrusion object discrimination in an intrusion monitoring system using optical fibers. More particularly, the present invention relates to a method of receiving a detection signal in a sliding window method in a window in a time domain. Detects the presence of intrusion through the amplitude (power) of the signals, and performs the Four Fourier Transform (FFT) on the signals in the latitude, depending on the number of changes in magnitude (positive slope) in the frequency component. The present invention relates to a method of distinguishing an invasive object (a person and a vehicle).

Conventionally, intrusion surveillance systems have been developed that detect intrusions using optical fibers. Such a system is used merely for detecting an intrusion, and does not detect what kind of an intruded object is.

Therefore, the development of a method that can detect the type of intrusion object in the intrusion monitoring system using the optical fiber is desired.

The present invention was developed to meet the above-described prior art requirements, and an object thereof is to provide an intrusion detection and intrusion object discrimination method using an optical fiber that can distinguish whether a detected object is a person or a vehicle. .

In order to achieve the above object, the intrusion detection method using the optical fiber according to the present invention includes a first step of converting a signal sensed by the monitoring system into a digital signal in the monitoring system using the optical fiber; And sliding the time window of a predetermined size with respect to the changed digital signal sample data by sliding all the sample data in the time window, and determining whether there is an intrusion according to the sum value. It is done.

In order to achieve the above object, intrusion object classification method using the optical fiber according to the present invention, if it is determined that the intrusion by the above-described intrusion detection method, FFT (Fast Fourier) for all the sample data in the time window A third step of performing a transform; And a fourth step of counting a positive slope with respect to the FFT-converted data and classifying the invasive object based on the number of counts.

The third step may include: a third step of obtaining a sum value of all sample data for a predetermined number of time windows while moving the time window by one sample data; Step 3-2 of selecting a maximum value from the sum values obtained in step 3-1 and the sum values obtained in step 2; And performing an FFT on all sample data in the time window corresponding to the selected maximum value.

In the fourth step, when the count is greater than a predetermined value, the intrusion object is classified as a vehicle, and when the count is less than or equal to a predetermined value, the intrusion object is classified as a person.

In the present invention configured as described above, when the intrusion object is detected in the optical fiber, a change in the optical signal occurs according to the signal processing to distinguish whether the intrusion and the intrusion object. First, the electrical signal due to the change of the optical signal is continuously sampled, and the magnitude of the sampled signals is summed over a predetermined time window to determine whether an invasion occurs. The time window is positioned when the sum of the sample data amplitudes is maximized so that such a valid signal (intrusion signal) can be completely included. In this case, a fast fourier transform (FFT) is performed on the sampling signal to count the number of times the sampling signal increases, and when the number is greater than or equal to a predetermined threshold, the sensing object is determined as a vehicle. Judge as a person.

1 is a view schematically showing a system to which intrusion detection and intrusion object discrimination methods using optical fibers according to the present invention are applied;

2 is a flow chart of the intrusion detection and intrusion object identification method using the optical fiber according to the present invention;

3 is a detection waveform diagram of a person in the time domain detected by the method according to the present invention;

4 is a sensing waveform diagram of a vehicle in a time domain detected by the method according to the present invention;

5 is a waveform diagram of a person and a vehicle in a frequency domain after FFT conversion of a sense waveform in the method according to the present invention;

6 is a view showing the number of changes in the inclination of the person and the vehicle in the frequency domain of the detection signal in the method according to the present invention.

** Explanation of symbols for main parts of drawings **

110: optical fiber 120: light source generator

121: laser diode 122: laser diode driver

123: laser diode stabilization circuit

130: reflection mirror 140: light branch

160: optical isolator 170: space filter

180: light receiving unit 181: photodiode

190: analog signal processing unit 200: analog / digital conversion unit

210: central processing unit

Hereinafter, an intrusion detection and distinguishing method using an optical fiber according to an embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a view schematically showing an example of a system to which an intrusion detection and discrimination method using an optical fiber according to the present invention is applied.

As shown in the figure, the intrusion monitoring system using the optical fiber, the optical fiber 110 having a certain length and embedded or embedded in the boundary of the monitoring area to serve as an optical path medium and a sensor; A light source generator 120 for generating a coherent optical signal and allowing the generated light to enter through one end 111 of the optical fiber 110; In order to reflect the optical signal transmitted forward through the optical fiber 110 and exited through the other end 112 of the optical fiber 110 to the reverse direction of the transmission direction, that is, to one end 111 of the optical fiber 110, A high reflecting optical fiber mirror 130 serving as a reflecting means provided so that a reflecting surface is in contact with the light emitting surface of the other end 112 of the optical fiber 110; The optical signal incident through one end 111 of the optical fiber 110 and forward-transmitted into the optical fiber 100 proceeds as it is, and the optical signal reflected by the optical fiber mirror 130 and transmitted backward is transmitted to the auxiliary optical fiber 150. An optical splitter 140 composed of an optical coupler or a beam splitter in order to branch-transmit to the side); An auxiliary optical fiber 150 serving as a path medium and / or a sensor for transmitting a reverse optical signal branched by the optical branch 140; An optical isolator (160) installed at a portion of the optical fiber (110) between the light source generator (120) and the optical branch (140) to block the progress of the reverse optical signal; A spatial filter 170 for filtering the optical signal emitted through the terminal 151 of the auxiliary optical fiber 150; An optical receiver 180 which receives the optical signal emitted through the terminal 151 of the auxiliary optical fiber 150 and passes through the spatial filter 170 and converts the optical signal into an electrical signal; An analog signal processor (190) for amplifying the electrical signal converted by the optical receiver (180); An analog / digital converter 200 for converting the analog signal amplified by the analog signal processor 190 into a digital signal; And a central processing unit 210 that detects an intrusion using the output digital signal of the analog / digital conversion unit 200 and determines whether the detected intruder is a person or a vehicle by an algorithm.

The central processing unit 210 may be configured using a microprocessor or a digital signal processor. In addition, the central processing unit 210, under the control of the central processing unit 210, LED driving unit 220 for displaying the result of intrusion detection and the distinction of the intrusion object (person or vehicle) through the LED 240 And a speaker driver 230 for sounding through the speaker 250.

In addition, a commercial personal computer 270 is connected to the central processing unit 210 through an interface 260, so that the intrusion detection result and the distinction result of the intrusion object (person or vehicle) can be displayed on the monitor. In addition, the detection result and the distinguishing result may be stored in a database by time zone.

In addition, the function of the central processing unit 210 may be performed in a commercial computer. In this case, the components 210, 220, 230, 240, and 250 may be removed, and the output of the analog / digital converter 200 may be transmitted through the interface 260. What is necessary is just to input into the personal computer 270.

The light source generator 120 includes a laser diode 121, a laser diode (LD) driver 122 for driving coherent light by driving the laser diode 121, and the laser diode 121. It consists of a laser diode (LD) stabilization circuit unit 123 for maintaining a stable operation of the light receiving unit 180 is composed of one or more photodiode (PD) (181) for receiving a laser light signal.

Next, the operation of the system will be described.

First, coherent light from the laser diode 121 driven by the LD driver 122 is incident through one end 111 of the optical fiber 110. Light incident on the optical fiber 110 is forwarded through the optical isolate 160 and the optical coupler 140 and then through the optical fiber 110 serving as a sensor, and the forwarded light is transmitted to the optical fiber. It encounters the reflective surface of the high reflectance optical fiber mirror 130 at the end cross section of 110, where most of the light is reflected in the opposite direction to the incident direction. The reflected light travels back through the optical fiber 110 to reach the optical coupler 140 and then is branch-delivered to the auxiliary optical fiber 150 by the optical coupler 140. The optical signal that reaches the terminal 151 of the auxiliary optical fiber 150 is emitted and passed through the spatial filter unit 170, and then received by the photodiode 181 of the optical receiver 180.

The optical signal received by the photodiode 181 of the optical receiver 180 is converted into an electrical signal through a preamplifier (not shown) and amplified by the analog signal processor 190, and the amplified analog signal is The analog / digital conversion unit 200 converts the digital signal into a digital signal at a speed of 10 kHz, for example, and detects an intrusion in the central processing unit 210 using the converted digital signal, and determines whether the intrusion object is a person or a vehicle. Will be distinguished.

In addition, the LD stabilization circuit unit 123 monitors the output from the laser diode 121 so that light of a certain wavelength and size is always output from the laser diode 121. The optical isolator 160 prevents the light reflected from the mirror 130 and transmitted in the reverse direction from being fed back to the laser diode 121. The shielding part 240 using an external protective material such as a copper tube that can surround the optical fiber 110 and the auxiliary optical fiber 150 is a part of the optical fiber 110 in contact with the laser diode 121, the light receiving part 180 A portion of the auxiliary optical fiber 150 in contact with the photodiode 181, and a portion of the auxiliary optical fiber 150 located inside the building or not in the monitoring area are blocked from being transmitted to the optical fibers 110 and 150 by external pressure or vibration. .

The optical fiber 110 is embedded in the basement of the place where you want to monitor the intruder to a depth of several centimeters or tens of centimeters depending on the monitoring area conditions, or installed in the fence and the optical fiber 110 is pressed by the vibration or pressure when the intruder invades When the light is reflected by the inner wall of the optical fiber 110 and changes the phase of the light traveling or going straight, the speckle pattern is changed, and thus the amount of light received through the photodiode 181 of the light receiving unit 180 is changed. The change and the received light signal is amplified by the analog signal processing unit 190 is input to the central processing unit 210 through the analog / digital changing unit 200.

The central processing unit 210 controls the LED driver 220 to display the result of the intrusion detection and intrusion object (person or vehicle) according to the algorithm described with reference to FIG. The speaker driving unit 230 is controlled to be pronounced through the speaker 250. In addition, the CPU 210 transmits the sensing result and the distinguishing result to the personal computer 270 through the interface 260, and the personal computer 270 displays the sensing result and the distinguishing result on a monitor. At the same time, the database is stored.

2 is a flowchart of a method for detecting and distinguishing intrusion using an optical fiber according to the present invention.

The CPU 210 detects an intrusion using the flowchart shown in FIG. 2 and distinguishes whether the intrusion object is a person or a vehicle.

In other words, the presence or absence of intrusion (or detection) and the distinction of the object are performed in a digital signal processing algorithm using a sliding time window method. The sliding time window method is a method of sliding while keeping the window window at a constant size. The sliding time window used in the algorithm is sized to include a signal measured after intrusion (or detection).

Accordingly, first, the number of samplings corresponding to the time window size of the digital signal converted into the digital signal at a rate of 10 kHz by the analog / digital converter 200 is set to n. Then, to add while sliding the amplitude (power) magnitude of the n samples, the i th sample which is the sum start sample is set as the first sampled sample, and the n th sample which is the sum end sample is set as the n th sample (step S1). .

Thereafter, the sizes of these sample data are summed in a time window set to n samples for the i th sample data to the N th sample data (steps S2 to S3).

Subsequently, the sum value P _sum of the summed sample data in the time window is compared with the intrusion (or detection) signal threshold value P _th (step S4).

If the sum value P _sum of the sample data is larger than P _th , it is determined that an intrusion (or detection) has occurred.

In this case, the i-th sample, which is the sum start sample, is set as the (i + 1) -th sampled sample, and the N-th sample, which is the summation end sample, is set so that the sliding time window is in a position where the intrusion (or detection) signal can be completely included. Set the (N + 1) th sample and slide the time window by one sample while adding the magnitude values of the sampling signals in each time window to the t time windows to add the sum of the sample data of each time window (P _{sum_1} , P _{sum_2} , ..., P _{sum_t} ) is obtained (steps S5 to S9).

Thereafter, a maximum value is selected from the sum values P _sum , P _{sum_1} , P _{sum_2} ,..., And P _{sum_t} of the obtained sample data of each time window (step S10).

Since the size of the time window is constant, when the sum of sample data in the time window has the maximum value after the intrusion (or detection) occurs, it is determined that the window is in a position capable of completely including the intrusion (or detection) signal. It is to. In the time domain, the detection signals of the person and the vehicle have speed and appearance characteristics, and as shown in FIGS. 3 and 4, the person has one large waveform and the vehicle has two large waveforms. However, these external features seen in the time domain cannot be used as a determinant of an algorithm that can clearly distinguish two signals. This is because the shape of these signals is not constant and varies with time and place.

Subsequently, an FFT (Fast Fourier Transform) is performed on all sample data in the time window corresponding to the selected maximum value (step S11) to convert the signal in the time domain into a signal in the frequency domain to obtain signals of human and vehicle. Find the property and use it as a judgment factor.

FIG. 5 shows the signals of the person and the vehicle in the frequency domain after taking the FFT, and through these diagrams, the characteristics of the two signals, which are the core of the algorithm of FIG. 2, can be found. The number of positive slope changes (the positive slope change when the magnitude of the i + 1th signal is large by comparing the magnitude of the i-th sampling signal with the magnitude of the i + 1th sampling signal) is larger than that of the positive slope.

Using this characteristic, after performing the FFT on the signal, the number of positive slopes is counted in the signals in the frequency domain (step S11 ′), and the number of slope changes STN is the slope change count threshold STN _th (for example, If larger than 4 times, the intruder is a vehicle and if the number of times is less than the threshold value, it is judged as a person (steps S12 to S14).

6, when the intruder is a human, the positive slope appears once at the point A in the signals of the frequency domain in the time window, whereas when the intruder is a vehicle, the positive slope is at the points B1 to B11. Many will appear.

On the other hand, if the sum value (P _sum ) of the sample data is less than P _th in step S4 described above, it is determined that no intrusion (or detection) has occurred, and in step S15, the i th sample, which is the sum start sample, is determined as (i + 1). After setting the N th sample, the N th sample which is the summation end sample, and the (N + 1) th sample, the time window is slid by one sample, and the above steps S2 to S4 are repeated.

The present invention configured as described above is not only intrusion monitoring but also other application fields, for example, if a person accidentally steps on a detection line at a driver's license test site, it does not affect the judgment system at all, and a signal is sent to the judgment system only when a vehicle is detected. It can be used in various ways by expanding the field of industrial use such as being delivered.

On the other hand, the present invention is not limited to the above-described typical preferred embodiment, it can be carried out in various ways without departing from the gist of the present invention various modifications, changes, substitutions or additions in the art Anyone who has this can easily understand it. If the implementation by such improvement, change, replacement or addition falls within the scope of the appended claims, the technical idea should also be regarded as belonging to the present invention.

As described in detail above, according to the present invention, as well as the presence or absence of an intrusion (or detection) object, the intrusion (or detection) object can be applied to various industrial fields as it is distinguished from a person or a vehicle. For example, it detects only the course deviation of the vehicle while preventing errors caused by the intrusion monitoring system of the unmanned security system, the course deviation detection of the vehicle at the driver's license examination center, and the detection of the course deviation sensor due to the carelessness of a person at the driver's license examination ground. It is a useful invention that can be used as a system, a foot switch in a door, and the like.

Claims (4)

In the monitoring system using the optical fiber, A first step of converting the signal detected by the surveillance system into a digital signal; And sliding the time window of a predetermined size with respect to the changed digital signal sample data by sliding all the sample data in the time window, and determining whether there is an intrusion according to the sum value. Intrusion detection method using optical fiber. A third step of performing a Fast Fourier Transform (FFT) on all sample data in the time window when it is determined that the intrusion is made by the method defined in claim 1; And a fourth step of counting a positive slope with respect to the FFT-converted data and classifying the intruder based on the number of counts thereof. The method of claim 2, The third step may include: a third step of obtaining a sum value of all sample data for a predetermined number of time windows while moving the time window by one sample data; Step 3-2 of selecting a maximum value from the sum values obtained in step 3-1 and the sum values obtained in step 2; And performing a third to third FFT on all sample data in the time window corresponding to the selected maximum value. The method of claim 2 or 3, In the fourth step, the intrusion object is classified as a vehicle when the count is greater than a predetermined value, and the intrusion object is classified as a person when the count is less than a predetermined value.