JP2001014561A - System for detecting dubious person - Google Patents

Abstract

PROBLEM TO BE SOLVED: To immediately detect that a dubious person intrudes into a warning area. SOLUTION: A plurality of sensors (1-1,... 1-n) which radiate radio waves of a prescribed frequency to specified spots (2-1,...2-n), receive reflected waves and detect a temporal displacement signal of an object in the spots according to the phase change of a received signal are arranged to cover a prescribed area. A device for recognition which detects the radio waves radiated from the sensors, modulates the waves with an ID signal and transmits them is attached to an optional place of an authorized person coming into/out of the area. Then, the sensors detect the temporal displacement signal and ID signal of an object within a spot and discriminate a dubious person according to the existence/absence of the displacement signal and the ID signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for discriminating an authorized person from a suspicious person, detecting that the suspicious person has entered the alert area, and issuing an alarm when necessary.

[0002]

2. Description of the Related Art Conventionally, surveillance cameras have been installed to check for suspicious persons or persons who have performed suspicious actions. However, it is almost impossible for a surveillance camera to immediately and accurately discriminate whether a person is a suspicious person in a place where many people enter and leave. for that reason,
In order to more reliably prevent suspicious persons from entering a place where a large number of people enter and exit, ID
And the ID is read by the reader installed at the gate.
There is known a system for reading wirelessly or the like and checking whether or not the user has a correct ID.

[0003]

However, in a system for checking an ID, it is necessary to limit the places where people enter and leave. However, in many cases, such a limitation is difficult. Not enough for security. Further, since it is necessary to be checked through the gate without fail, there is a possibility that the execution of the job may be hindered depending on the contents of work such as a cargo handling area. In recent years, there has been no end to the cases of poisoning and sewing needles, and there is a need for the construction of a security system that prevents such incidents from occurring in cargo handling areas where it has been difficult to prevent the entry of suspicious persons.

An object of the present invention is to solve the above-mentioned problem, and it is an object of the present invention to eliminate the necessity of providing a check gate or the like and to immediately detect a suspicious person who has entered the alert area.

[0005]

According to the present invention, there is provided a micro-beam detecting device for radiating a radio wave of a predetermined frequency to a specific spot, receiving a reflected wave, and detecting a temporal displacement signal of an object within the spot from a phase change of a received signal. A system in which a plurality of wave sensors are arranged, a predetermined area is covered by a plurality of specific spots, and a processing device is provided which takes in signals from the respective microwave sensors and processes the data, wherein any of an authorized person entering and exiting the predetermined area A recognition device attached to a location, which detects radio waves radiated from the microwave sensor, modulates the ID signal with an ID signal, and transmits the modulated signal as an authorized person recognition signal. It is characterized in that a displacement signal and an ID signal for authorization person recognition are detected. Further, the present invention detects the temporal displacement of the object by the microwave sensor, and when the ID signal is detected,
It is characterized in that it is determined to be an authorized person. Further, the present invention is characterized in that a temporal displacement of an object is detected by a microwave sensor, and when no ID signal is detected, the object is determined to be a suspicious individual. Further, the present invention is characterized in that when the temporal displacement of the object is not detected by the microwave sensor and the ID signal is detected, it is determined that the recognition device has been forgotten.

[0006]

Embodiments of the present invention will be described below. FIG. 1 is a diagram for explaining a warning spot in the present invention, FIG. 1 (a) is a diagram viewed three-dimensionally, and FIG. 1 (b).
FIG. 2 is a plan view of a warning spot, and FIG. 2 is a view for explaining a cap for an approver for discriminating whether a person is a suspicious person. FIG. 1 (a)
, The sensors 1-1 to 1-n are microwave sensors (details will be described later), and radiate radio waves from the antennas so as to cover the warning spots 2-1 to 2-n shown in FIG. Receiving the reflected wave, detecting the movement (displacement) of a person or a small animal in the alert spot from the phase shift of the reflected wave, and determining whether a recognition signal has been detected or not. Or discrimination. As a sensor, a visible light or infrared sensor must have a light receiving unit or a light emitting unit exposed due to its characteristics, and may be detected by an intentional intruder. On the other hand, a microwave sensor using radio waves can cover the surface with a dielectric, and can keep secret where the sensor is. Microwave sensors may be installed at appropriate positions such as a ceiling or a wall, and the warning spots may be slightly separated from each other or may partially overlap each other. The cost can be saved if no sensor is arranged in a portion that does not require vigilance. The radio wave used by the microwave sensor is within the range permitted by the Radio Law (for example, 30 MHz or more).
And with much lower output than mobile phones,
Electromagnetic noise, no impact on health.

In FIG. 2, a recognition device 4 is attached to an approver's cap 3, which detects a detection radio wave 5 transmitted from a sensor and obtains information on an ID assigned to the approver, for example, an M-sequence. The signal is modulated by a code (or modulation of frequency assignment and amplitude modulation are also possible) and transmitted as a radio wave 6 for recognition. The recognition device 4 is an active reflector that amplifies the detected radio wave and retransmits it as a reflected wave. Since the detection radio wave is used as a carrier, a carrier oscillator is not necessary. For example, a planar antenna is used as an antenna for transmitting and receiving radio waves. In this case, the recognition device 4 is attached to the approver's hat. However, the present invention is not limited to this. A part of the uniform (belt, pocket, etc.), gloves, shoes, etc. You may make it attach to a place which does not get in the way.

FIG. 3 is a conceptual diagram of a suspicious individual detection system according to the present invention. The signals detected by the sensors 1-1 to 1-n are taken into a signal processing device (CPU) 10, where the information of the movement of a person or a small animal and the ID information of the radio wave for recognition are used to determine whether or not the person is a suspicious person. The determination is made, and the result is output to the display 11 and the alarm 12, and is transferred to the host computer 13. For example, a large number of people are moving in a cargo handling place or the like, and the movement of a person or a small animal in the alert spot is detected by each sensor, and the ID information of the radio wave for recognition is taken in at the same time. The signal processing device 10 includes, for example, a motion detection flag F1 (“1” when motion is detected, “0” otherwise) and an ID information detection flag F2 (“1” when correct ID information is detected). , And otherwise "0"), and when both the flag F1 and the flag F2 are "1", the authorized person, and when the flag F1 is "1" and the flag F2 is "0", the suspicious person (or Small animal), flag F1 is "0", flag F2
Is "1", it is determined that the authorized person's hat is left. The signal processing device 10 is a control panel or the like placed in an office or the like, and is centrally managed by the host computer 13. Of course, the signal processing device 10 itself may be used as a host computer for centralized management.

Next, the microwave sensor will be described. FIG. 4 is a block diagram showing an example of a circuit structure of a heterodyne-type transmitter and a receiver constituting a sensor. In the transmitter 20, the output of the high frequency (intermediate frequency) generator 21 is passed through a distributor / combiner 22 and an amplifier 23 to the mixer 2.
At 4, the signal is mixed with the output of the local oscillator 38, frequency-converted, supplied to the transmission coaxial cable 28 via the amplifier 25, the distributor / combiner 26, and the amplifier 27, and transmitted as a detection radio wave 5 from an antenna (not shown). Radiated, forming a vigilance spot. The reflected wave from the alert spot and the radio wave for recognition 6 are received by the receiver 30. The received signal on the receiving coaxial cable 37 passes through an amplifier 31, a subtractor 32 and an amplifier 33, is mixed with an output of a local oscillator 38 by a mixer 34, converted into an intermediate frequency, and passed through an amplifier 35 to a detector 3.
6 and a pair of detection outputs E ₁ having a phase difference of 90 °.
And it is converted to E _2. The branch output e _p of the distributor / synthesizer 26 in the transmitter is supplied to an unnecessary reflected wave canceling signal generator 39, and the output e _{q of the} generator 39 is subtracted by the subtractor 3 in the receiver.
2 is supplied. The branch output e _c of the distributor / combiner 22 in the transmitter is supplied to the detector 36.

FIG. 5 is a diagram showing the internal configuration of the detector.
Signal e _r from the amplifier 35 of the receiver 30 is 2 minutes,
One is supplied to the multiplier 361 as a multiplicand signal, and the other is supplied to the multiplier 362 as a multiplicand signal. Also,
The branch output e _c of the distributor / combiner 22 in the transmitter is also divided into two, one of which is supplied as it is to the multiplier 361 as the multiplier signal e _c , and the other is passed through the 90 ° phase shifter 363 and the multiplier 36.
It supplied as multiplier signal e _s to 2. Multipliers 361 and 3
The outputs synchronously detected at 62 are output from the low-pass filter 3 respectively.
64, 365, the quadrature component detection outputs E ₁ and E ₂
Becomes

FIG. 6 is a diagram showing the internal configuration of the unnecessary reflected wave canceling signal generator. Branch output e _p of the distributor / combiner 26 in the transmitter, the variable phase shifter 391 and the variable attenuator 392, phase and amplitude respectively is regulated, unnecessary reflected wave cancellation signal e _q.

Here, the operation of the circuits shown in FIGS. 4 to 6, particularly the operation of the receiver will be described. In general, the transmission signal e _T and the reception signal e _R are: e _T = a _T cos ω ₀ t (1) e _R = a _R cos ω ₀ (t−τ) (2) a _T , a _R : constant ω ₀ : angle The frequency = 2πf ₀ f ₀ can be represented by, for example, 1200 MHz t: time τ = 2R / VR R: distance to reflector V: radio wave speed

[0013] For simplicity of explanation, the subtracter 32 is assuming no received signal e _r input to the detector 36 is converted to an intermediate _{frequency, e r = a r cosω (} t-τ) ( 3) ω: Intermediate angular frequency after frequency conversion = 2πff f can be represented by, for example, a formula of 10 MHz.

On the other hand, the signal is branched by the distributor / combiner 22.
Part of transmission signal e_cIs e_c= A_ccosωt (4). The multiplier 361 calculates e_cAnd e_r
Multiplied by e_c× e_r= A_mcosωtcosω (t−τ) = (1/2) a_m{Cosω (2t−τ) + cosωτ} (5) a_m= A_r× a_c Also, e_cIs shifted by 90 °_sAnd e_rAnd the multiplier
362 multiplied by e_s× e_r= (1/2) a_m{Sin ω (2t−τ) + sin ωτ} (6) In the expressions (5) and (6), when the right side is expanded
The first term has twice the frequency of the radiated radio wave, but the second term
Is constant when the reflector is a stationary object,
Even in the case of a moving body, the frequency of the change is
Extremely low. Therefore, the outputs of these multipliers are
And through low-pass filters 364 and 365, equation (5) and
And the component corresponding to the first term on the right side of equation (6) is removed,
Detection output E ₁And E_TwoIs E₁= (1/2) a_mcosωτ (7) E_Two= (1/2) a_msinωτ (8).

The above description is for any one reflected wave. Therefore, the phase of the reflected wave from a moving object to be detected, for example, a living body (the time required for a radio wave to return) is _denoted by τ ₀ , obstacles other than, i.e., if the representative phase of the reflected wave from the stationary object in tau _n, the detection output E ₁ and E _{2, E 1 = (1/2) a} m cosωτ 0 + (1/2) a _{m 'cosωτ n (9) E} 2 = (1/2) a m sinωτ 0 + (1/2) a m' should be sinωτ _n (10).

The second term on the right-hand side of the above two equations is noise, which is irrelevant to the object to be detected. However, usually, a _m '
Is significantly larger than a _m, so
The term, that is, the signal corresponding to the detection target is buried in the noise, and sufficient sensitivity cannot be obtained. Therefore, a subtractor 52 and an unnecessary reflected wave canceling signal generator 39 (FIG. 4) are provided. The phase and amplitude of the branched output e _p of the distributor / combiner 26, the variable phase shifter 391 and variable attenuator 392 (FIG. 6), was adjusted to them and cheek equal major component of the received signal from the amplifier 31 , Is supplied to a subtractor 32, and subtracted from the received signal from the amplifier 31. Actually, while monitoring the output of the subtractor 32 with a level meter or the like, the variable phase shifter 391 and the variable attenuator 392 may be adjusted so as to minimize the output. As a result, the amplitude of the second term on the right side of the equations (9) and (10) can be reduced to such an extent that detection processing for the first term described below is not hindered.

The distance between the moving object to be detected and the antenna depends on the movement of the moving object, for example, the respiration of a living body,
It slightly fluctuates according to the heartbeat, the movement of each part of the body, and the like, and as a result, the phase τ ₀ of the reflected wave from the object fluctuates. Therefore, the moving object to be detected can be detected by examining the change in the expressions (9) and / or (10). If the average value of the distance to the detection target is represented by R ₀ and the variation is represented by r, Here, since 2ω / V and R ₀ are constant, (2ω / V
V) If R ₀ = A, 2ω / V = B, then equation (9) and (1
Equation (0) can be rewritten as follows. However, the remainder of the unnecessary reflected wave signal reduced as described above is represented by {E ₁ }
Expressed in E _2, the _{E 1 = (1/2) a m} cos (A + Br) + △ E 1 E 2 = (1/2) a m sin (A + Br) + △ E 2.

However, since R ₀ is about several meters and r is at most about several cm, | A | ≫ | B
r | a and, therefore, the following approximate expression _{E 1 ≒ (1/2) a m} {cosA-BrsinA} + △ E 1 (11) E 2 = (1/2) a m {sinA + BrcosA} + △ E 2 (12) holds.

When the right-hand side of these two equations is expanded, the first and third terms are constant, that is, DC components, and thus can be removed by a high-pass filter.
The change in the reflected wave signal indicated by the term, that is, the movement of the moving object to be detected can be detected. Here, the reason for generating the detection outputs E ₁ and E ₂ having phases different from each other by 90 degrees will be explained.
In OSA, when A i.e. (2ω / V) R ₀ is close to an integral multiple of π because the sinA ≒ 0, becomes impossible detection by E _1, | cos A | since the ≒ 1, E ₂ Is the maximum, and A is π
When it is close to an integral multiple of / 2, cosA ≒ 0, so that detection by E ₂ becomes impossible, but | sinA | ≒
Since the 1, the sensitivity of detection by E ₁ becomes maximum. Therefore, regardless of the value of A, a situation in which detection is not possible can be avoided.

FIG. 7 is a diagram showing an example of a circuit for detecting a moving object from the detection outputs E ₁ and E ₂ . The high-pass filters 40 and 41 remove DC components from the detection outputs E ₁ and E ₂ , respectively. As a result, only the signals corresponding to the second term on the right side of the equations (11) and (12) are amplified by the amplifiers 42 and 43.
Amplified by The amplified output is converted into a digital signal by A / D converters 44 and 45, respectively, and then supplied to an arithmetic operation circuit 46, where equations (11) and (12)
Is calculated, and the result is subjected to spectrum analysis by the fast Fourier transformer 47, and a signal corresponding to the displacement r is obtained from the obtained power spectrum.

Next, the discrimination of the approver will be described. FIG. 8 is a diagram showing the circuit configuration of the recognition device provided in the authorizer's hat. The detection radio wave received by the receiving antenna 52 is amplified by the amplifier 53, multiplied by the ID signal stored in the ROM 50 by the mixer 51, and radiated as a recognition radio wave from the antenna 55 via the amplifier 54. Now, the gains of the amplifiers 53 and 54 are G ₁ and G ₂ , and the ID signal is m
When the radio wave radiated from the microwave sensor is represented by (t) and has the angular frequency ω ₀ as shown in the equation (1),
The radio wave for recognition e _D reflected from the recognition device and received by the microwave sensor is given by e _D = kG ₁ G ₂ m (t−τ / 2) cosω ₀ (t−τ−τ ′) (13) expressed. Here, τ ′ is a system time delay. Then, if it is converted into the intermediate frequency ω in the sensor,
Focusing only on the cos component of the output of the detector 36 (FIG. 4), e _c × e _D = k′G ₁ G ₂ m (t−τ / 2) cosωtcosω (t−τ−τ ′) (14) , The output E of the low-pass filter 364 or 365
_{3, E 3 = (k'G 1 G} 2/2) m (t-τ / 2) cosω (τ + τ ') becomes (15). _{(K'G 1 G 2/2)} , cosω (τ + τ ')
Can be regarded as constant, so that a signal corresponding to the ID signal m (t−τ / 2) is obtained. On the other hand, the output E _{4 in} the case of a signal of a person having no ID is given by m (t−τ /
2) corresponds to _{= 1, E 4 = (k'G} 1 G 2/2) cosω (τ + τ ') is expressed as (16), (11), as in the case of (12), a low pass filter Only a displacement signal can be obtained by passing through. In this way, it is possible to discriminate whether or not the person is an authorized person.

FIG. 9 is a diagram for explaining another modulation method in the recognition device. In this example, the detection radio wave is modulated by changing the gain of the amplifier 56 based on the ID data stored in the ROM 50. Figure 8 shows the discrimination of the licensee
Is the same as

FIG. 10 is a diagram showing a circuit configuration for detecting displacement and discriminating an approver using homodyne detection. FIG.
In the above, the heterodyne method is used for the microwave sensor, but the present invention may use the homodyne method. In addition,
For convenience, the description will be omitted with the frequency conversion part omitted. The output of the high-frequency oscillator 61 is amplified by the amplifier 62 and
, And a reflected wave is received by the antenna 65.
The signal amplified by the amplifier 66 and the signal from the directional coupler 63 are shifted from each other by λ / 8 on the waveguide, that is, 9
Mixing and detection are performed by the diodes D at the positions where the phases are shifted by 0 °, respectively.
_1, and outputs the E _2. This output corresponds to the output in FIG. 4. Even if this circuit is used, a displacement signal and an approver discrimination signal can be similarly obtained.

Note that the present invention is not limited to the above example, and various modifications are possible. For example, a simulated ID signal is superimposed on a transmission wave, and the operation of the sensor can be checked based on whether or not the simulated ID signal can be decoded from the received signal. In addition, the location of the person having the ID can be known in spot units, and the movement information of the person can be recorded. If there is no displacement signal and only the ID signal can be obtained, it can be used as a countermeasure for forgetting the authorized person's hat. In addition, by communicating with the host computer, it is possible to obtain information on the presence or absence of people at the required places when necessary, and by linking with a surveillance camera, it is possible to immediately monitor the site when an abnormality occurs It is. Further, a sensor for identifying an authorized person may be provided in each microwave sensor separately from the microwave sensor.

[0025]

As described above, according to the present invention, it is possible to discriminate an authorized person from a suspicious person by using a simple device, and immediately detect that the suspicious person has entered a security spot, and Since there is no possibility that the intruder can intentionally detect the sensor installation position, it is possible to exert a great effect in preventing a suspicious person from entering a place where a large number of people enter and exit, such as a cargo handling area.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a warning spot according to the present invention.

FIG. 2 is a diagram illustrating an authorized person hat for discriminating whether a person is a suspicious person or not.

FIG. 3 is a conceptual diagram of a suspicious person detection system of the present invention.

FIG. 4 is a block diagram showing an example of a circuit structure of a heterodyne transmitter and a receiver.

FIG. 5 is a diagram showing an internal configuration of a detector.

FIG. 6 is a diagram showing an internal configuration of an unnecessary reflected wave canceling signal generator.

FIG. 7 is a diagram showing an example of a circuit for detecting a moving object from a detection output.

FIG. 8 is a diagram showing a circuit configuration of a recognition device provided in a cap for an approver.

FIG. 9 is a diagram illustrating another modulation method in the recognition device.

FIG. 10 is a diagram showing a circuit configuration using a homodyne detection method.

[Explanation of symbols]

1-1 to 1-n ... microwave sensor, 2-1 to 2-n ...
Warning spot, 10 ... Signal processing device, 11 ... Display, 1
2 ... Alarm, 13 ... Host computer, 20 ... Transmitter, 21 ... High frequency generator, 22, 26 ... Distributor / combiner,
24, 34 ... mixer, 23, 25, 27, 31, 33,
35 amplifier, 28 transmission coaxial cable, 30 receiver 32, subtractor 32, 36 detector, 37 reception coaxial cable 38 local oscillator 39 unnecessary reflected wave canceling signal generator 39 361, 362 multipliers, 364, 3
65 low-pass filter, 391 variable phase shifter, 392 variable attenuator 392, 40, 41 high-pass filter, 42, 4
3 amplifier, 44, 45 A / D converter, 46 arithmetic circuit, 47 fast Fourier converter, 50 ROM, 5
1: Mixer, 52: Receiving antenna, 53, 54, 56 ...
Amplifier, 55 antenna, 61 high frequency oscillator, 62,
66 ... amplifier, 63 ... directional coupler, 64, 65 ... antenna.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masayuki Nagatsuka 5-19-21 Komaoka, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture F-term in Daiwa Electric Industry Co., Ltd. 5C084 AA02 AA07 AA08 AA16 AA19 BB31 CC16 CC26 DD08 EE10 FF27 GG03 GG07 GG09 GG13 GG20 GG24 GG37 GG38 GG42 GG43 GG52 GG56 GG57 GG73 GG74 GG75 HH01 HH10 5J070 AB16 AB20 AC02 AD02 AE09 AF01 AH40 AK24 BC06 BC08 BC16

Claims (4)

[Claims] 1. A plurality of microwave sensors for radiating a radio wave of a predetermined frequency to a specific spot, receiving a reflected wave, and detecting a temporal displacement signal of an object in the spot based on a phase change of a received signal, A system that includes a processing device that covers a predetermined area with the specific spot of the above, takes in the signal of each microwave sensor, and processes the data, and is attached to an arbitrary place of an authorized person who enters and exits the predetermined area, The apparatus includes a recognition device that detects a radio wave radiated from the sensor, modulates the ID signal with an ID signal, and transmits the modulated signal as a licenser recognition signal. A suspicious person detection system, wherein the ID signal is detected. 2. The suspicious device according to claim 1, wherein the processing device detects a temporal displacement of the object using a microwave sensor, and determines that the user is an authorized person when an ID signal is detected. Person detection system. 3. The processing device according to claim 1, wherein the processing device detects a temporal displacement of the object using a microwave sensor, and determines that the object is a suspicious individual when an ID signal is not detected. Suspicious person detection system. 4. The processing device according to claim 1, wherein when the microwave sensor detects no temporal displacement of the object and an ID signal is detected, it is determined that the recognition device has been forgotten. Suspicious person detection system as described.