KR102141735B1 - Laser transceiver using intruder detection and method for detecting intruder - Google Patents

Abstract

Disclosed are a laser transceiver and an intruder detection method used for intruder detection. The disclosed laser transceiver is a laser transceiver used to detect an intruder who invades a target object, and includes a laser transmitter that transmits a transmission signal to the laser transceiver A, wherein the laser transmitter generates a signal that generates a laser pulse signal of a single sideband. part; At least one filter unit including a capacitor that performs filtering on the laser pulse signal A of the generated single-sided band; And at least one laser diode that transmits a laser pulse signal of a single sideband output from the at least one filter unit, respectively, and the transmission signal is a signal output from the at least one laser diode.

Description

Laser transceiver using intruder detection and method for detecting intruder

Embodiments of the present invention relates to an intruder detection method using a laser having a false positive probability and a false positive probability and a laser transceiver performing the same.

In general, a laser generator is used to send a beam with sufficient power to be distinguished by a detector, and if the beam is completely turned on or off during the sampling period, an intruder can be detected by the detector. In particular, if the beam is sent with sufficient power to be distinguished by the detector, and if the beam does not reach the sensor completely because the line of sight is disturbed by the intruder during the sampling period, this problem becomes a detection problem solved in the communication field. However, an experienced intruder can easily fool such a system.

In the case of the prior art, in order to generally defend a target object (eg, a house, a military facility, etc.), a microwave transceiver that transmits and receives a microwave signal around the target object is placed like a fence, and the line of sight of the microwave signal by a specific target If this disturbance occurs, it is determined that there is an intruder when the amount of reduced energy of the received microwave signal is greater than a threshold.

This conventional technique is not effective in detecting intruders in some hazardous environments. For example, when defending a border, the probability of a false positive and a false positive of a detector must be zero. Otherwise, the erroneous alarm can lead to confusion, and if the intruder is not detected, some damage to the sentry or even life is lost. As another example, if the probability of false positives and false positives of a detector that keeps your home safe is high, you can put people inside your home at risk. Therefore, it is important to develop a detector with a false positive probability and a zero false detection probability.

In order to solve the problems of the prior art as described above, the present invention proposes a method for detecting an intruder using a laser having a false positive probability and a false detection probability of 0, and a laser transceiver performing the same.

Other objects of the present invention may be derived by those skilled in the art through the following examples.

According to a preferred embodiment of the present invention to achieve the above object, the laser transceiver used for detecting an intruder invading a target object, a laser transmitter for transmitting a transmission signal to the laser transceiver A; includes, but the laser The transmitter comprises: a signal generator for generating a laser pulse signal of a single-sided band; At least one filter unit including a capacitor that performs filtering on the laser pulse signal A of the generated single-sided band; And at least one laser diode that transmits a laser pulse signal of a single sideband output from each of the at least one filter unit, wherein the transmission signal is a signal output from the at least one laser diode. A transceiver is provided.

The signal generation unit may be connected in parallel with the capacitor included in the at least one filter unit and the at least one laser diode.

The laser transceiver further includes a receiving unit that receives a signal transmitted from the laser transceiver B and measures the SNR of the received signal to determine whether the intruder has invaded, but the transmitted signals have different phases. The branch includes a laser pulse signal of at least one single-sided band, and the received signal may include the transmitted signal, an additive Gaussian white noise signal, and a noise signal according to the disturbance of the intruder.

When the SNR measured in the received signal is equal to or less than a predetermined threshold, the receiver determines that the intruder has invaded, and the SNR can be expressed by the following equation.

Here, SNR(r) is the SNR for the received signal, R is the Fourier transform coefficient of the received signal, and E is the Fourier transform coefficient of the signal received by the receiver when R and the intruder do not invade. Difference vector, * means each complex number symbol.

In addition, according to another embodiment of the present invention, a method performed in a device including a processor and detecting an intruder invading a target object, comprising: measuring an SNR of a received signal for a signal transmitted from a laser transceiver B ; And determining that the intruder has invaded if the SNR is less than or equal to a preset threshold, wherein the transmitted signal includes at least one single-sideband laser pulse signal having a different phase, and the received The signal includes the transmitted signal, the additive Gaussian white noise signal and the noise signal according to the disturbance of the intruder, and the SNR is provided as an intruder detection method characterized in that it is expressed by the following equation.

Here, SNR(r) is the SNR for the received signal, R is the Fourier transform coefficient of the received signal, and E is the Fourier transform coefficient of the signal received by the receiver when R and the intruder do not invade. Difference vector, * means each complex number symbol.

According to the present invention, the computational complexity of intruder detection is linear with respect to the data size, can be implemented with a microprocessor, and has the advantages of false detection probability and zero detection probability.

In addition, it should be understood that the effects of the present invention are not limited to the above-described effects, and include all effects that can be deduced from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a diagram showing a schematic configuration of an intruder detection system 100 according to an embodiment of the present invention.
2 is a diagram showing a schematic configuration of each of a plurality of laser transceivers according to an embodiment of the present invention.
3 is a diagram showing a schematic configuration of a transmitting unit according to an embodiment of the present invention.
4 is a view showing a schematic configuration of a receiving unit according to an embodiment of the present invention.
5 to 7 are views for explaining the simulation of the present invention.
8 to 10 are diagrams for explaining an implementation example of the intruder detection system of the present invention.
11 is a flowchart illustrating a method of detecting an intruder according to an embodiment of the present invention.

As used herein, a singular expression includes a plural expression unless the context clearly indicates otherwise. In this specification, terms such as “consisting of” or “comprising” should not be construed as including all of the various components, or various steps described in the specification, among which some components or some steps are It may not be included, or it should be construed to further include additional components or steps. In addition, terms such as “... unit” and “module” described in the specification mean a unit that processes at least one function or operation, which may be implemented in hardware or software, or a combination of hardware and software. .

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram showing a schematic configuration of an intruder detection system 100 according to an embodiment of the present invention.

Referring to FIG. 1, a plurality of laser transceivers 120 are disposed around a target object 110 like a fence at specific intervals (for example, at 30 cm intervals), and adjacent signals transmitted from one laser transceiver 120 are adjacent to each other. It is received from the other laser transceiver 120, and the other laser transceiver 120 determines whether an intruder has invaded using the received signal.

That is, each of the plurality of laser transceivers 120 transmits or receives signals to other adjacent laser transceivers 120 in order to detect an intruder entering the boundary between two areas inside and outside the fence. The received laser transceiver 120 determines whether an intruder has invaded using the received signal.

2 is a diagram illustrating a schematic configuration of each of a plurality of laser transceivers 120 according to an embodiment of the present invention.

Referring to FIG. 2, each of the plurality of laser transceivers 120 may have the same structure, and includes a transmitter 210 and a receiver 220. At this time, as described above, the transmitter 210 performs a function of transmitting a signal to the laser transceiver A (for example, a laser transceiver adjacent to the left side of the laser transceiver 120), which is another adjacent laser transceiver, and the receiving unit ( 220) detects an intruder by receiving a signal transmitted from another adjacent laser transceiver, the laser transceiver B (for example, the laser transceiver adjacent to the right side of the laser transceiver 120).

At this time, the transmitter 210 transmits a transmission signal corresponding to an artificially generated single-sided band laser pulse signal, not a signal existing in nature, to the laser transceiver A. The laser transceiver A performs intruder detection based on the received signal. Then, the receiving unit 220 receives a received signal corresponding to the single-sided band laser pulse signal transmitted from the laser transceiver B, and the laser transceiver B determines whether an intruder has invaded using the received signal.

3 is a diagram showing a schematic configuration of a transmitter 210 according to an embodiment of the present invention.

Referring to (a) of FIG. 3, the transmitter 210 serves as a laser generator, and includes one signal generator 211, at least one filter unit 212, and at least one laser diode 213. It includes. And, Fig. 3 (b) shows the configuration of the transmission unit 210 when only one filter unit 212 and a laser diode 213 are present.

The signal generator 211 generates a laser pulse signal of a single sideband. Hereinafter, for convenience of description, the laser pulse signal of the single-sided band generated by the signal generator 211 will be referred to as “laser pulse signal A of the single-sided band”.

Each of the at least one filter unit 212 performs filtering (for example, LPF (Low Pass Filter) filtering) on the laser pulse signal A of the single-sided band generated by the signal generator 211, and includes a capacitor for this. do. That is, the capacitor performs a function of changing the phase of the laser pulse signal A of the single-sided band generated by the signal generator 211. In one example, the capacitor serves to push the phase of the laser pulse signal A. At this time, the capacities of the capacitors included in each of the at least one filter unit 212 may be different.

Each of the at least one laser diode 213 transmits the laser pulse signal A of the single-sided band output from the corresponding filter unit 212 to the laser transceiver A. Therefore, a single-sideband laser pulse signal having different phases can be transmitted to the laser transceiver A. In this case, the single-sideband laser pulse signals having different phases may be orthogonal sub-signals.

That is, according to the present invention, the transmission signal transmitted from the transmitter 210 corresponds to a laser pulse signal of at least one single-sided band that is a signal output from the at least one laser diode 213, which is not artificial in nature. Is a signal. Accordingly, the probability of false positives and false positives associated with detection of an intruder can be guaranteed to be “0” as described below using at least one single-sided laser pulse signal.

On the other hand, in the connection relationship of the transmitter 210, the signal generator 211 may be connected in parallel with each of the at least one capacitor and the at least one laser diode.

4 is a diagram showing a schematic configuration of a receiving unit 220 according to an embodiment of the present invention.

Referring to FIG. 4, the receiver 220 serves as a detector, and may include at least one photodiode 221 and one detector 222.

At least one photodiode 221 receives a signal generated and transmitted by the laser transceiver B. At this time, the received signal may be a laser pulse signal B of a single sideband including a server signal having at least one phase.

Then, the detection unit 222 measures the transmission power and the SNR (signal-to-noise ratio) of the received signal to determine whether the intruder has invaded.

Hereinafter, the operation of the receiver 220 will be described in more detail.

The receiver 220 receives a laser pulse signal of a single-sided band, which is a transmission signal transmitted from an adjacent laser transceiver. At this time, the received signal includes an additive Gaussian white noise signal (AGWN). In addition, when an intruder passes between two laser transceivers, a line-of-sight (LOS) of a signal transmitted and received by the laser transceiver by the intruder is lost, which causes another noise. That is, when there is no intruder, the received signal has only small dispersion AGWN, but when the intruder intrudes, it causes loss of LOS, and the received signal does not reach the laser transceiver that acts as a detector by the intruder and does not reach the AGWN Only exists. Therefore, the receiver 220 should recognize the loss of the LOS and the ASWM without confusion.

Meanwhile, the received signal received from the receiver 220 may include a transmitted signal, an additive Gaussian white noise signal, and a noise signal according to disturbance of an intruder, which is expressed as Equation 1 below. Can.

Here, r(t) is a received signal received from the receiver 220, s(t) is a transmitted signal transmitted from the laser transceiver B (corresponds to the laser pulse signal B of the single sideband), and n(t) is additive The Gaussian white noise signal (AGWN) and n _a (t) refer to noise signals generated by disturbance, respectively. And, N is the number of orthogonal sub-signals processed by the receiver 220, w _n is the frequency of each sub-signal, φ _n is the phase of each sub-signal, A _n (t) is the intensity of the sub-signal (amplitude) , X _n (t) is a Gaussian distribution with mean 0 and variance 1 X _n (t) to N(0, 1) random variable, Y _n (t) is Gaussian distribution with mean 0 and variance 1 Each means a random variable having Y _n (t) to N(0,1).

In the absence of an intruder, Y _n (t) is zero for time t, and the received signal r(t) has a Gaussian distribution with small variance as described above. However, if an intruder intrudes and interferes with the LOS, for every n and time t, each of A _n (t) is reduced and each Y _n (t) is added. That is, the transmission signal s(t) decreases and AGWN n(t) increases.

Meanwhile, in order to distinguish the two cases, the sum of the powers of the sub-signals of the received signal r(t) may be used, and the receiver 220 may detect the intruder using the transmitted signal power and the SNR.

On the other hand, in the present invention, it is assumed that the intruder interferes with the loss of the rage by the ratio λ _t to the time domain according to the Poisson process. At this time, the average number of events in the time interval T is λ _t T. In addition, in the present invention, it is assumed that the intruder interferes with the LOS according to the Poisson process at a ratio λ _d for the frequency domain. If the total number of sub signals is N, the average number of distributed sub signals is λ _d N.

In order to detect such an abnormal phenomenon, it is necessary to divide the transmission signal into AGWN and abnormal noise, or recognize noise in the transmission signal. The waveform of the transmitted signal can provide many types of information including phase and frequency.

For the present invention, Monte Carlo simulation is used to estimate the parameters of the probability distribution. Then, the probability of false positives is calculated using the density function for the received signal mixed with AGWN, the probability of undetected is calculated using the density function for the signal mixed with AGWN, and the density of the noisy signal is calculated. Find the probability of detecting abnormal noise from the function.

At this time, the false positive problem may be hypothesis testing on test statistics, or hypothesis testing on the average power of the transmitted signal or the SNR and noise of the transmitted signal. These decision problems include hypothesis H ₀ in the absence of an intruder and hypothesis H ₁ in the presence of an intruder.

Observed received signal vector r=[r(0), r(1),… , r(T)] (T is a sampling period), the receiver 220 has a false positive probability (P(FA)=P(H ₁ |H ₀ )) and a false positive probability (P(Miss)=P Calculate test statistic γ(r) such that (H ₀ |H ₁ ) becomes 0. That is, P(γ(r)|H ₀ ) and P(γ(r)|H ₁ ) Calculate the test statistics γ(r) that sufficiently distinguish the probability distribution.

At this time, the threshold γ is defined, which can be expressed as Equation (2).

Here, P(FA) = P(γ(r) <γ| H ₀ ), P(Miss) = P(γ(r)> γ| H ₁ ), and the probability of detection is P(Detection) = P(γ (r) <γ|H ₁ ).

Regarding the test statistics γ(r), first, the average power of the received signal is used first. That is, a matched filter is used to estimate the average power of the transmission signal s(t) from the received signal r(t). The match filter can be used to maximize the SNR of the received signal, and is expressed by Equation 3 below.

Then, after the match filter H is applied to the Fourier transform coefficient F of the received signal r(t), only the real part of the complex number, which is the applied result, is used. At this time, in the case of a non-coherent receiver, the complex number has a non-zero imaginary part. Then, the real part of the complex number is divided by the sampling period T and the number N of sub-signals. Therefore, the test statistics are expressed as Equation 4 below.

)의 푸리에 변환 계수,

는 복소수의 실수 파트, *는 켤래 복소수의 기호,

는 두 벡터의 내적 연산을 각각 의미한다. Where F is the Fourier transform coefficient of the received signal r(t), S is the transmitted signal S(

) Fourier transform coefficient,

Is the real part of a complex number, * is the sign of a complex number,

Denotes the dot product operations of the two vectors, respectively.

In addition, a test statistic SNR as shown in Equation 5 below is used for comparison of noise and average power of the transmitted signal.

는 수신 신호 r(t)에 대한 푸리에 변환 계수 F와 송신 신호 s(t)에 대한 푸리에 변환 계수 S에 대한 차이 벡터, E는 송신 신호 s(t)의 에너지, N₀는 AGWN의 평균 전력, N_a는 교란으로 발생되는 잡음의 평균 전력, S(W)는 송신 신호 s(t)의 푸리에 변환을 각각 의미한다. Where S is the Fourier transform coefficient for the transmitted signal s(t),

Is the difference vector for the Fourier transform coefficient F for the received signal r(t) and the Fourier transform coefficient S for the transmitted signal s(t), E is the energy of the transmitted signal s(t), N ₀ is the average power of the AGWN, N _a is the average power of the noise generated by the disturbance, and S(W) means the Fourier transform of the transmission signal s(t), respectively.

Sufficient statistics are defined as a function of observations that can yield a likelihood ratio. The match filter is a sufficient statistic to estimate a parametric vector that is not definitively known in a linear model with AGWN. In other words, when the noise is AGWN, the output of the general match filter is sufficient statistics to calculate the previous distribution of the received signal r(t) and known θ.

In summary, the receiver 220 may determine that the intruder has intruded when the SNR measured in the received signal corresponding to the laser pulse signal B of at least one single-side band is equal to or less than a preset threshold. In one example, the threshold may be 20dB. In addition, the SNR may be expressed as Equation 6 based on Equation 5 above.

Here, SNR(r) is the SNR for the received signal r(t), R is the Fourier transform coefficient of the currently received received signal r(t), E is R, and if the intruder does not invade, it is received by the receiver 220 The difference vectors of the Fourier transform coefficients of the signal to be referred to respectively.

And, the present invention can provide excellent performance at a lower cost than the conventional by using the signal generator 212 and the beam generator and the laser diode for generating a low-cost single-sided band laser pulse signal. In particular, with regard to zone safety applications, the intruder detection system 100 of the present invention can be used with a video monitoring system.

Hereinafter, the simulation of the present invention will be described with reference to FIGS. 5 to 7.

Referring to the above drawings, in the case of this simulation, Monte Carlo simulation is performed using a Matlab program. In FIG. 5, each box shows the result obtained by repeating the experiment 10,000 times, and the number N of sub signals is 32 for each receiver. For simulation, we make the following assumptions. Disturbance by the intruder interferes with the transmitted signal according to the Poisson process. By the definition of the Poisson process, the probability of two or more events or disturbances occurring at the same time is almost zero. The sampling time interval (eg, 512 ms) is very short compared to the disturbance time (eg, about 250 ms) caused by the human hand. Therefore, the probability that two or more disturbances or events occur simultaneously during this sampling time interval is almost zero. The distance (e.g., 10 cm) between two laser emitters (i.e., the transmitter 210) transmitting a signal received by the detector (i.e., the receiver 220) is the body (e.g. , Hand) is relatively small compared to the size. Therefore, the probability of interference (or event) occurring more than once in this space is almost zero. The Poisson process is a calculation process in which the number of events occurring at independent time intervals has independent incremental characteristics. Therefore, it is assumed that an intrusion occurring at a sampling time interval of 512 ms is independent of other interventions occurring at the next sampling time interval even if the same intruder interferes. And, it is assumed that the interference of the sub-signals processed by one detector during a given time interval is independent of any other intervention of the sub-signals processed by other detectors, even if the same intruder interferes.

The Poisson process also has a fixed increase and decrease characteristic that the distribution of the number of events occurring at any time interval depends only on the length of the time interval. Since the disturbance rate for the sampling time interval is half of the total sampling time, λ _t =1/2, the average number of events for the sampling time is λ _t T = (1/2)T. The disturbance rate for the total number of sub-signals is assumed to be half of the total number of sub-signals or λ _d =1/2. Therefore, the average number of events for N sub-signals processed by one detector is λ _d N = (1/2)N.

If more than half of all sub-signals or the entire sampling period is disturbed, disturbance can be easily detected. Therefore, we use these assumptions to test cases that are relatively difficult to detect. The amplitude of AWGN has a Gaussian distribution with mean zero and variance 1, and the disturbance has a Gaussian distribution with the same parameters. The probability distribution of all received signals is a Lysian distribution.

If an intruder is present, there is no LOS, the amplitude of the received signal is zero, and only Gaussian noise reaches the detector. In this case, the Raysian distribution becomes the Rayleigh distribution. That is, if there is no LOS or P(γ(r)|H ₁ ), the power distribution is a Rayleigh distribution.

When LOS is present and the SNR is sufficiently greater than 1 (eg, SNR=5), the Lysian distribution becomes the Gaussian distribution. That is, if LOS is present or P(γ(r)|H0), the power distribution is a normal distribution.

5(a) shows and gives the power distribution of the match-matched filtered signal. 5( b) shows the SNR distribution of the received signal. The sample sizes of the box pairs are 512, 256, 128 and 64 respectively.

Each pair of boxes shows the distribution of test statistics with and without intruders for various sample sizes T. The first box of each pair of boxes shows the distribution of statistics (or power or SNR) for the presence of intruders or P=(γ(r)|H ₁ ). The second upper limb shows the distribution for P=(γ(r)|H ₁ ) in the absence of an intruder. The Shapiro-Wilk test confirms that each probability distribution of the test metric for P(γ(r)|H ₀ ) is a normal distribution.

The quantile-quantile plot shown in FIG. 6(a) shows the power distribution of the match filtered signal for sample size 512, in the case of an intruder or P(Power|H ₁ ). The quantile-quantile plot shown in (b) of FIG. 6 includes a Gaussian distribution and shows the power distribution of the match filtered signal for sample size 512, in the absence of an intruder or P(Power|H ₀ ).

The quantile-quantile plot shown in FIG. 7(a) shows that the SNR distribution when the sample size is 256 when there is an intruder deviates from the normal distribution. 7B shows the SNR distribution for the normal distribution P (SNR | H ₀ ).

On the other hand, Table 1 below shows thresholds for discrimination to make the false positive probability P(FA) and the false positive probability P(Miss) substantially zero. In addition, the maximum value of the statistical γ(r) is presented in case of disturbance. Table 1 further shows the parameters of the normal distribution for P(γ(r)|H ₀ ). At this time, it was found that the average power of the match-filtered signal is sufficient statistics for a large sample size 512.

Meanwhile, an implementation example of the intruder detection system 100 will be described below.

Unlike the conventional radar system, in the case of the waveform of the intruder detection system 100 of the present invention, since the reflected laser signal is not used, there is no Doppler shift in the incident laser signal. Therefore, we can transmit waveforms that cannot be generated by disturbances with as much power as possible. At this time, since the plurality of laser transceivers 120 use an inexpensive controller and hardware, processing complexity and hardware are limited. In particular, the low cost laser used cannot turn off in less than 8 milliseconds. It uses the analog output of the Arduino controller to shape the waveform of the laser signal. A low cost laser diode flashes the 650nm laser signal every 128ms. In order to generate a waveform as shown in FIG. 8, the laser diode is turned on at the beginning of each blink period (128 ms period), and the laser diode is turned off for 8 ms at 120 ms. In addition, a capacitor of 470uF that can be used up to a voltage of 10V is used.

Therefore, the received signal is modified as shown in equation (7).

Here, we use complex notation. In addition, the imaginary part of the complex number is the Hilbert transform of the real part.

Fig. 9 shows the power spectrum of the received signal. As shown in Fig. 9, the Fourier transform coefficient is zero for a positive frequency. The Fourier transform coefficient c (n) obtained by applying the FFT to the received signal is expressed by Equation 8 below.

At this time, for the transmitted waveform, Equation (5) was used to calculate SNRs with and without disturbances. As shown in Fig. 10, in the case of the present invention, we obtained experimental results consistent with the data in Fig. 5(b). The maximum SNR with disturbance is 14.49 dB lower than the minimum SNR with no disturbance. Each box in FIG. 10 shows the results obtained by repeating the experiment 100 times. The received signal has a sample size of 512.

11 is a flowchart illustrating a method of detecting an intruder according to an embodiment of the present invention. At this time, the above-described method may be performed in a receiving device through a processor. Hereinafter, the process performed for each step will be described in detail.

First, in step 1110, a signal transmitted from a laser transmitter is received. At this time, the transmitted signal includes laser pulse signals of at least one single-sided band having different phases.

Next, in step 1120, the SNR of the received signal is measured.

At this time, the received signal includes a transmission signal, an additive Gaussian white noise signal, and a noise signal according to an intruder's disturbance.

Subsequently, in step 1130, if the SNR is equal to or less than a preset threshold, it is determined that the intruder has invaded.

At this time, the SNR may be expressed as Equation 6 above.

So far, embodiments of the intruder detection method according to the present invention have been described, and the configuration of the intruder detection system 100 described with reference to FIGS. 1 to 10 can be applied to the present embodiment as it is. Accordingly, a more detailed description will be omitted.

In addition, embodiments of the present invention may be implemented in the form of program instructions that can be executed through various computer means and can be recorded in computer readable media. The computer-readable medium may include program instructions, data files, data structures, or the like alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the present invention, or may be known and available to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs, DVDs, and magnetic media such as floptical disks. Examples of program instructions, such as magneto-optical, and ROM, RAM, flash memory, etc., can be executed by a computer using an interpreter as well as machine code such as those produced by a compiler. Contains high-level language codes. The hardware device described above may be configured to operate as one or more software modules to perform the operation of one embodiment of the present invention, and vice versa.

As described above, in the present invention, it has been described by specific matters such as specific components, etc. and limited embodiments and drawings, which are provided to help the overall understanding of the present invention, but the present invention is not limited to the above embodiments, Those skilled in the art to which the present invention pertains can make various modifications and variations from these descriptions. Therefore, the spirit of the present invention should not be limited to the described embodiments, and should not be determined, and all claims that are equivalent or equivalent to the scope of the claims as well as the claims described below will be included in the scope of the spirit of the invention. .

Claims (5)

In the laser transceiver used to detect intruders invading the target object,
A laser transmitter for transmitting a transmission signal to the laser transceiver A; And
Includes a; receiving unit for receiving a signal transmitted from the laser transceiver B, and measuring the SNR for the received signal to determine whether the intruder has invaded or not;
The laser transmission unit, a signal generator for generating a laser pulse signal of a single-sided band; At least one filter unit including a capacitor that performs filtering on the laser pulse signal of the generated single-sided band; And at least one laser diode that transmits a laser pulse signal of a single sideband output from the at least one filter unit, respectively.
The transmission signal is a signal output from the at least one laser diode,
The signal transmitted from the laser transceiver B includes at least one laser pulse signal of a single sideband having a different phase, and the received signal is in the disturbance of the transmitted signal, the additive Gaussian white noise signal, and the intruder. Noise signal,
When the SNR measured in the received signal is equal to or less than a preset threshold, it is determined that the intruder has intruded.
The SNR is expressed by the following equation,
The receiving unit calculates test statistics such that the false positive probability and the false positive probability are zero,
A match filter is applied to the Fourier transform coefficient of the received signal in relation to the test statistics,
The following equation is expressed based on a test statistic SNR used for comparing the average power of the transmitted signal and the noise signal.

Here, SNR(r) is the SNR for the received signal, R is the Fourier transform coefficient of the received signal, and E is the Fourier transform coefficient of the signal received by the receiver when R and the intruder do not invade. Difference vector, * means each complex number symbol. According to claim 1,
The signal generator is a laser transceiver, characterized in that connected to the capacitor and the at least one laser diode included in the at least one filter unit in parallel. delete delete A method for detecting an intruder that is performed on a device including a processor and intrudes into a target object,
Measuring the SNR of the received signal with respect to the signal transmitted from the laser transmitter; And
Including when the SNR is below a predetermined threshold value, determining that the intruder has invaded;
The transmitted signal includes a laser pulse signal of at least one single-sided band having different phases, and the received signal includes the transmitted signal, an additive Gaussian white noise signal, and a noise signal according to the disturbance of the intruder. Includes,
The SNR is expressed by the following equation,
The device calculates test statistics such that the false positive probability and the false positive probability are zero,
A match filter is applied to the Fourier transform coefficient of the received signal in relation to the test statistics,
Equation below is an intruder detection method characterized in that it is expressed based on the test statistics SNR used to compare the average power of the transmitted signal and the noise signal.

Here, SNR(r) is the SNR for the received signal, R is the Fourier transform coefficient of the received signal, and E is the difference vector between the R and the Fourier transform coefficient of the received signal when the intruder does not invade. , * Means each complex number symbol.

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