JP2011007518A - Device, system and method for detecting suspicious person - Google Patents

Abstract

PROBLEM TO BE SOLVED: To specify the number of suspicious persons and their locations even when a plurality of suspicious persons invade.SOLUTION: A delay time change analyzing part 105 extracts a frequency component of temporal fluctuation (delay time change) of a delay time until a wide-band pulse signal is reflected by a reflection source and received as an incoming wave after the pulse signal is transmitted, and a reflection source determining part 106 determines whether the reflection source of the incoming wave is a moving body with breathing and heartbeats, such as a human body, or a fixed object such as a wall or an article, based on the frequency component of the temporal fluctuation (delay time change) of the delay time of an inputted incoming wave. By using a wide-band UWB pulse signal as a transmission pulse, besides, the incoming waves are separated on the time axis, and therefore it is possible to detect the suspicious persons invading an area and to detect the number of the suspicious persons.

Description

  The present invention relates to a suspicious person detection device, a suspicious person detection system, and a suspicious person detection method using UWB (Ultra-Wide-Band) pulse radio.

  In recent years, using a wireless IC (Integrated Circuit) card, a wireless IC card reader has been placed at the entrance and exit of a specific area such as an office to authenticate whether a person entering or exiting the area is permitted to enter the area. The system is generally known. In such a system, it is necessary to hold the IC card over the card reader when entering or leaving, and there is a problem that it takes time.

  As a system for solving this problem, Patent Document 1 discloses a security system using a microwave radio signal.

  In the security system of Patent Document 1, a plurality of base stations covering a specific range are arranged, and the base station determines whether or not a person entering the cover range carries a tag and does not carry a tag , Warn that a suspicious person has newly entered.

  A base station that transmits a microwave signal and a tag that receives a signal transmitted from the base station and transmits the signal to the base station again. By receiving a signal from the tag, the base station detects that a registered person has entered the area managed by the base station. On the other hand, the reflected wave from the human body is used to detect that a person who does not have a tag not registered in advance enters the area.

  However, the signal received by the base station is received from various reflected waves such as a transmitted wave from the tag, a reflected wave reflected from the wall, a reflected wave reflected from a fixture, and a reflected wave reflected from a moving body such as a human body. Yes. Therefore, it is necessary for the base station to determine which reflecting object the reflected wave is from.

  Since the reflected wave from the tag is modulated using a pseudo-random sequence such as the M sequence, whether the reflected wave from the tag depends on whether the M sequence can be extracted from the demodulation result of the received signal. It can be determined whether or not. If the M series can be extracted from the received signal, it can be determined that the reflected wave is from the tag.

  On the other hand, in order to distinguish a reflected wave from a fixed object such as a wall or a fixture from a reflected wave from a human (suspicious person), the security system disclosed in Patent Document 1 performs frequency analysis of a received signal. When a suspicious person who does not have a tag enters the area, it is possible to analyze the reflected wave and detect that the suspicious person has entered from the frequency characteristics.

Japanese Patent No. 3763454

  However, since the above-described security system uses a microwave radio signal, it is difficult to detect how many suspicious persons have entered the area when a plurality of suspicious persons have entered the area. This is because a plurality of reflected waves from the suspicious person are added together at the base station and appear as one received signal. For this reason, the above security system can distinguish whether the added incoming wave is a reflected wave from a fixed object such as a wall or a fixture, or a reflected wave from a human, but there are multiple reflection sources. In this case, it becomes difficult to distinguish it.

  Although the reflected wave from a suspicious person can be separated by simply applying UWB (Ultra-Wide-Band) pulse radio to the security system described in Patent Document 1, the security described in Patent Document 1 is used. Since the system distinguishes whether it is a reflected wave from a fixed object or a reflected wave from a human using a signal obtained by shifting the transmission signal by 90 °, a 90 ° phase-shifted signal in the UWB band is generated. Therefore, the circuit configuration becomes complicated.

  An object of the present invention is to provide a suspicious person detection device, a suspicious person detection system, and a suspicious person detection method that specify the number of suspicious persons and the positions of suspicious persons even when a plurality of suspicious persons enter.

  The suspicious person detection device according to the present invention includes a transmission unit that transmits a wide-band pulse signal at predetermined intervals, a reception unit, and a generator that generates a delay profile of the reception signal received by the reception unit at each predetermined interval. Means for detecting, for each reflection source, an arrival wave in which the broadband pulse signal is reflected by a reflection source by detecting a peak of the delay profile; and the transmission means for detecting the broadband pulse signal. Based on the frequency component of each reflection source and the analysis unit for analyzing the frequency component of the time fluctuation of the delay time from the transmission until the reception unit receives the incoming wave Determining means for determining whether the reflection source is a moving object or a fixed object.

  The suspicious person detection device according to the present invention includes a transmission unit that transmits a wide-band pulse signal at predetermined intervals, a reception unit, and a generator that generates a delay profile of the reception signal received by the reception unit at each predetermined interval. Means for detecting, for each reflection source, an arrival wave in which the broadband pulse signal is reflected by a reflection source by detecting a peak of the delay profile, and a temporal change in the reception intensity of the arrival wave. Analyzing means for analyzing the frequency component of fluctuation for each reflection source, and determination means for determining whether the reflection source is a moving object or a fixed object based on the frequency component for each reflection source.

  The suspicious person detection system according to the present invention is the suspicious person detection apparatus described above, wherein a delay time from when the transmission unit transmits the broadband pulse signal to when the reception unit receives the incoming wave. Based on the distance measurement means for measuring the distance to the reflection source, and the arrival direction measurement means for measuring the arrival direction of the received incoming wave, the determination means comprising the measured distance and Based on the direction of arrival, the suspicious person detecting device for specifying the position of the reflection source, receiving means for receiving the wideband pulse signal transmitted from the suspicious person detecting device, and the received wideband A terminal comprising: an adding means for adding a tag ID unique to the device to the pulse signal; and a transmitting means for amplifying and transmitting the pulse signal with the tag ID added thereto. That.

  The suspicious person detection method of the present invention transmits a broadband pulse signal at predetermined intervals, generates a delay profile of the received signal at each predetermined interval, and detects the peak of the delay profile, thereby detecting the broadband pulse. An incoming wave in which a signal is reflected by a reflection source is detected for each of the reflection sources, and a frequency component of temporal fluctuation of a delay time from when the pulse signal is transmitted until the arrival wave is received, Analysis is performed for each reflection source, and whether the reflection source is a moving object or a fixed object is determined based on the frequency component for each reflection source.

  The suspicious person detection method of the present invention transmits a broadband pulse signal at predetermined intervals, generates a delay profile of the received signal at each predetermined interval, and detects the peak of the delay profile, thereby detecting the broadband pulse. An incoming wave whose signal is reflected by a reflection source is detected for each of the reflection sources, and a frequency component of temporal fluctuation of the reception intensity of the incoming wave is analyzed for each of the reflection sources, and the frequency for each of the reflection sources is analyzed. Based on the component, it is determined whether the reflection source is a moving object or a fixed object.

  According to the present invention, even when a plurality of suspicious persons enter, suspicious persons can be detected separately.

The block diagram which shows the principal part structure of the suspicious person detection apparatus which concerns on Embodiment 1 of this invention. The figure which showed the reference signal transmitted from the suspicious person detection apparatus which concerns on Embodiment 1. FIG. The figure which showed the surrounding environment assumed in this invention The figure which showed an example of the delay profile measured in the environment shown by FIG. Illustration for explaining the change of the reflective surface when a human breathes The block diagram which shows the principal part structure of the suspicious person detection apparatus which concerns on Embodiment 2 of this invention. Diagram showing the measurement environment built in the anechoic chamber Diagram showing another measurement environment built in an anechoic chamber The figure which shows the frequency analysis result of the reflected wave which is reflected by the metal plate The figure which expanded a part of Drawing 8A The figure which shows the frequency analysis result of the reflected wave which is reflected by the human body Fig. 9A is an enlarged view of a part of The figure which showed the whole structure of the suspicious person detection system which concerns on Embodiment 3 of this invention. The block diagram which shows the principal part structure of the suspicious person detection apparatus which concerns on Embodiment 3. FIG. Flow chart for explaining a reflection source determination method according to Embodiment 3 The block diagram which shows another principal part structure of the suspicious person detection apparatus which concerns on Embodiment 3. FIG.

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

(Embodiment 1)
FIG. 1 is a block diagram showing a main configuration of the suspicious person detection device according to the present embodiment. 1 includes a reception antenna 101, a reception radio unit 102, a delay profile generation unit 103, a peak detection unit 104, a delay time change analysis unit 105, a reflection source determination unit 106, a pulse generation unit 107, and a transmission radio. Unit 108 and a transmission antenna 109.

  The reception antenna 101 receives a reflected wave of a pulse signal (transmission pulse) transmitted from the transmission antenna 109. The reception antenna 101 transmits the received pulse signal (reception pulse) to the reception radio unit 102.

  The reception radio unit 102 performs processing such as amplification, detection, AD (Analog to Digital) conversion, and the like on the input reception pulse, and converts it into a digital baseband signal. Reception radio section 102 transmits the converted digital baseband signal to delay profile generation section 103.

  The delay profile generation unit 103 generates a delay profile from the input digital baseband signal. A delay profile can be generated by transmitting a wideband pulse signal and detecting the received signal. The vertical axis represents the received intensity (received power) and the horizontal axis represents the delay time characteristics. It is. Here, the delay time is a time from when a broadband pulse signal is transmitted until the pulse signal is reflected by a reflection source and received as an incoming wave. Therefore, in the UWB system that transmits and receives impulses, the received signal is the delay profile itself. The delay profile generation unit 103 sends the generated delay profile to the peak detection unit 104.

  The peak detection unit 104 detects an inflection point that is convex upward in the input delay profile. An inflection point that is convex upward in the delay profile means the presence of an incoming wave. Therefore, the peak detection unit 104 obtains the time of the inflection point that is convex upward, and from the time when the pulse signal is transmitted from the transmission antenna 109 to the time when the incoming wave arrives at the reception antenna 101 and is received. The delay time can be obtained. The peak detection unit 104 detects the delay time of the incoming wave for each reflection source, and sends the detected delay time and reception intensity of the incoming wave to the delay time change analysis unit 105.

  The delay time change analysis unit 105 reflects the time fluctuation (delay time change) of the delay time of the incoming wave using the delay time information out of the input incoming wave information (delay time and received intensity). Analyze by source. The transmission pulse is repeatedly transmitted from a transmission antenna 109 described later. Therefore, the reflected wave of the transmission pulse transmitted from the transmission antenna 109 is also repeatedly received as an incoming wave by the suspicious person detection device 100. That is, the delay time change analysis unit 105 analyzes the time fluctuation (delay time change) of the delay time of the reflected wave (arrival wave) from different reflection sources. The frequency component that can be detected by the delay time change analysis unit 105 is determined by the transmission interval (repetition interval) of transmission pulses. For example, when the transmission interval (repetition interval) of the transmission pulse is 100 ns, the delay time change analysis unit 105 can detect the frequency component of the temporal fluctuation (delay time change) of the delay time of the incoming wave up to 10 MHz. . The delay time change analysis unit 105 sends the frequency component of temporal fluctuation (delay time change) of the delay time of the incoming wave to the reflection source determination unit 106 as an analysis result.

  The reflection source determination unit 106 detects only the arrival wave of a specific frequency component from the analysis result of the temporal fluctuation (delay time change) of the delay time of the arrival wave for each reflection source reflected by the different reflection sources. For example, if the frequency component of the temporal fluctuation (delay time change) of the delay time of the reflected wave from the human body is 0.5 Hz to 2 Hz, the reflection source determination unit 106 has a frequency component strong to 0.5 Hz to 2 Hz. Is detected, and the reflection source of the incoming wave is estimated to be a human body. The reflection source determination unit 106 determines whether or not the reflection source is a human body by determining whether or not the temporal fluctuation (delay time change) has a strong frequency component between 0.5 Hz and 2 Hz for all incoming waves. presume. The reflection source determination unit 106 determines the number of reflection sources estimated to be a human body and the delay time of incoming waves from the human body. Then, the reflection source determination unit 106 calculates the number of suspicious persons in the area from the number of incoming waves from the human body. Further, the reflection source determination unit 106 calculates the distance from the suspicious person using the result of the delay time of the incoming wave from the human body.

  The pulse generator 107 repeatedly generates a pulse signal at a constant period. As described above, the transmission pulse transmission interval (repetition interval) determines a detectable frequency component. Hereinafter, a case where the pulse generation unit 107 generates a pulse signal every 100 ns will be described as an example. Thereby, the delay time change analysis part 105 can detect the frequency component of the temporal fluctuation (delay time change) of the delay time of the incoming wave up to 10 MHz. The pulse generation interval is not limited to 100 ns, and may be determined in consideration of the frequency component of the temporal fluctuation (delay time change) of the delay time to be detected by the delay time change analysis unit 105. The pulse generation unit 107 sends the generated pulse signal to the transmission radio unit 108.

  The transmission radio unit 108 converts the input pulse signal into a radio frequency using a frequency conversion or oscillation circuit. The transmission radio unit 108 amplifies the pulse signal converted to the radio frequency, limits the band, and transmits the band signal to the transmission antenna 109.

  The transmission antenna 109 transmits the input pulse signal as a transmission pulse to the space.

  FIG. 2 is a diagram illustrating an example of a pulse signal transmitted from the transmission antenna 109. FIG. 2 is an example in which pulse signals are transmitted at 100 ns intervals. In FIG. 2, a transmission pulse 200 is a pulse signal transmitted first from the transmission antenna 109. A transmission pulse 201 is transmitted 100 ns after the transmission pulse 200 is transmitted. Similarly, the transmission pulse 202 and the transmission pulse 203 are sequentially transmitted at an interval of 100 ns. In this way, the transmission pulse is repeatedly transmitted at regular intervals.

  FIG. 3 is a diagram illustrating an example of a base station 300 on which the suspicious person detection device 100 is mounted and an environment around the base station 300. FIG. 3 illustrates the base station 300, a wall 301, a fixture 302, and a suspicious person 303. , An example of an environment including a wall 304 and a suspicious person 305 is shown.

  As illustrated in FIG. 2, the base station 300 repeatedly transmits a pulse signal, and receives the pulse signals reflected by the walls 301 and 304, the fixture 302, and the suspicious individuals 303 and 305.

  The wall 301 exists at the closest distance from the base station 300. The wall 301 reflects the pulse signal transmitted from the base station 300.

  The fixture 302 exists at the second closest distance from the base station 300. The fixture 302 reflects the pulse signal transmitted from the base station 300.

  The suspicious person 303 exists at the third closest distance from the base station 300. The suspicious person 303 reflects the pulse signal transmitted from the base station 300.

  The wall 304 exists at the fourth closest distance from the base station 300. The wall 304 reflects the pulse signal transmitted from the base station 300.

  The suspicious person 305 is present at the fifth closest distance from the base station 300. The suspicious person 305 reflects the pulse signal transmitted from the base station 300.

  FIG. 4 shows a situation in which the signal transmitted from the base station 300 is reflected by the walls 301 and 304, the fixture 302 and the suspicious persons 303 and 305 and received by the base station 300 again in the environment as shown in FIG. A delay profile is shown.

  In FIG. 4, the horizontal axis represents the delay time of the incoming wave, and the vertical axis represents the reception intensity (reception power) of the received pulse. In FIG. 4, t = 1 indicates a delay profile generated when the base station 300 receives the transmission pulse 200. Similarly, t = 2 indicates a transmission pulse 201, t = 3 indicates a transmission pulse 202, and t = 4 indicates a delay profile generated when the base station 300 receives the transmission pulse 203.

  In FIG. 4, an incoming wave 400 is an incoming wave reflected by the wall 301 and received by the base station 300. Since the wall 301 is a fixed object, the delay time of the signal reflected and received by the wall 301 does not change through the delay profile generated by the received pulse at t = 1-4.

  An incoming wave 401 is an incoming wave reflected by the fixture 302 and received by the base station 300. Since the fixture 302 is a fixed object, the delay time of the incoming wave reflected and received by the fixture 302 does not change through the delay profile generated by the received pulse at t = 1 to 4 like the incoming wave 400.

  The incoming wave 402 is an incoming wave reflected by the suspicious person 303 and received by the base station 300. The delay time of the incoming wave reflected and received by the suspicious person 303 is the same at t = 1 and 3, but is shorter or longer than t = 1 at t = 2 and 4. Thus, with respect to the reflected wave from the suspicious person 303, a temporal fluctuation occurs in the delay time. This fluctuation of the delay time occurs because the distance between the base station 300 and the reflection point slightly changes due to heartbeat or respiration when a signal is reflected by the human body of the suspicious person 303. The temporal fluctuation of the delay time will be described later.

  An incoming wave 403 is an incoming wave that is reflected by the wall 304 and received by the base station 300. As in the case of the wall 301, the delay time of the incoming wave reflected and received by the wall 304 does not change through the delay profile generated by the received pulse at t = 1-4.

  An incoming wave 404 is an incoming wave reflected by the suspicious person 305 and received by the base station 300. As in the case of the suspicious person 303, the delay time of the incoming wave reflected and received by the suspicious person 305 causes temporal fluctuation.

  As described above, the arrival wave reflected and received by the fixed object such as the wall or the fixture among the arrival waves reflected and received by the base station 300 does not change the delay time, and the time of the delay time is not changed. There is no fluctuation. On the other hand, the arrival wave reflected by the human body and received by the base station 300 is such that even when the human body is stationary, the reflection point of the signal slightly changes due to the heartbeat and breathing operation, so the delay time is the heartbeat and breathing. The time fluctuates in the delay time.

  The heart rate of a normal person is about 60 times per minute. In addition, the breathing of a normal person is about once every 2 seconds. Therefore, when the transmission signal transmitted from the base station 300 is reflected on the surface of the human body, the reflecting surface fluctuates at a frequency of about 0.5 Hz to 1 Hz. For this reason, when the reflected wave reflected from the surface of the human body is received by the base station 300, the delay time varies according to the heartbeat and the breathing cycle.

  In addition, in order to extract the characteristics of heartbeat and respiration, it is necessary to periodically transmit transmission pulses. Specifically, the repetition period of the transmission pulse may be shorter than the 0.5 second interval because the fluctuation of the human body surface is up to 1 Hz.

  The delay time change analysis unit 105 takes data for a certain period into an internal memory, and analyzes temporal fluctuations (delay time change) of the fetched data. At this time, the delay time change analysis unit 105 captures a data amount of 2 seconds or more into the memory so that a fluctuation having a frequency component of 0.5 Hz can be detected. Since the captured data is affected by noise, an error occurs. Therefore, in order to reduce the influence of noise, a pulse signal is transmitted with a period shorter than 0.5 second interval, and the average value of the delay time is calculated within a section within 0.5 seconds, thereby reducing noise resistance. Can be raised.

  In this manner, the delay time change analysis unit 105 extracts a frequency component of temporal fluctuation (delay time change) as a feature of human body variation. On the other hand, a reflected wave from a fixed object such as a wall or a fixture does not have such a feature because the reflection point does not fluctuate. In other words, a reflected wave from a fixed object such as a wall or a fixture has a feature that the delay time of the reflected wave does not change.

  FIG. 5 is a diagram for explaining a change in the reflection surface when a human breathes. In FIG. 5, the upper part represents a state when a human exhales, and the lower part represents a state when a human inhales. Here, the antenna 500 and the antenna 502 are the same antenna, and the human body 501 and the human body 503 are the same. In the upper stage, the pulse signal transmitted from the antenna 500 is reflected by the human body 501 and received by the antenna 500 again. Similarly, in the lower stage, the pulse signal transmitted from the antenna 502 is reflected by the human body 503 and received by the antenna 502 again. The surface of the human body repeatedly expands and contracts as it breathes. The state where the upper breath of FIG. 5 is exhaled represents a state where the surface of the human body 501 is most contracted, and the state where the lower portion of FIG. 5 is breathed represents the state where the surface of the human body 503 is expanded most. When attention is paid to the distance from the antenna that transmits and receives the pulse signal, a difference in distance from the transmission / reception antenna, that is, a path difference occurs between the state of the human body 501 and the state of the human body 503. This path difference means that the distance until the pulse signals transmitted from the transmitting and receiving antennas are reflected by the human bodies 501 and 503 and received again is different. Therefore, the time from transmission of the pulse signal to reception is different in the two states. In the upper part of FIG. 5, the delay time becomes longer, and in the lower part of FIG. 5, the delay time becomes shorter. Thus, when an incoming wave reflected by the human body is received, the delay time of the incoming wave changes in accordance with the breathing of the human body.

  The same applies to the expansion and contraction in the heartbeat. Similarly to breathing, the surface of the human body repeatedly expands and contracts in time with the heartbeat. Compared with respiration, the degree of expansion and contraction is small. Therefore, the temporal fluctuation (change in delay time) of the delay time of the incoming wave reflected from the human body is also smaller than that of respiration. Further, since the period of expansion and contraction is different from that of respiration, the frequency components extracted when analyzing the temporal fluctuation (delay time change) of the delay time of the incoming wave are different.

  Using these characteristics, the frequency component of the temporal fluctuation (delay time change) of the delay time of the incoming wave is detected, so that it is a reflected wave from a fixed object such as a wall or a fixture, or breathing, heartbeat It can be distinguished whether the reflected wave is from the accompanying human body.

  Furthermore, by using a wide-band UWB pulse signal as the transmission pulse, the signal reflected and received by the reflection source is separated on the time axis, and the incoming wave 402 and the incoming wave 404 can be distinguished from each other. Even when there are a plurality of incoming waves that can be identified as reflected waves of the human body by analyzing temporal fluctuations (changes in delay time), these can be distinguished. Therefore, even when there are a plurality of suspicious persons in the area covered by the base station 300, the plurality of suspicious persons can be distinguished and detected.

  Further, since a plurality of suspicious persons can be distinguished, it is possible to detect the number of suspicious persons who have entered the area.

  As described above, in the present embodiment, the delay profile generation unit 103 generates a delay profile from the input digital baseband signal, and the peak detection unit 104 calculates the delay time of the incoming wave from the delay profile for each reflection source. The delay time change analysis unit 105 analyzes the frequency component of the temporal fluctuation (delay time change) of the delay time of the arrival wave for each reflection source, and the reflection source determination unit 106 receives the input reflection source. Based on the frequency component of the time fluctuation (delay time change) of the delay time of each incoming wave, whether the reflection source of the incoming wave is a moving object with breathing or heartbeat such as a human body, or a fixed object such as a wall or a fixture Judgment was made. In addition, by using a wide-band UWB pulse signal as the transmission pulse, the incoming waves are separated on the time axis. Therefore, it is possible to detect suspicious persons who have entered the area and detect the number of suspicious persons.

(Embodiment 2)
FIG. 6 is a block diagram showing a main configuration of the suspicious person detection device according to the present embodiment. In the suspicious person detection device according to the present embodiment shown in FIG. 6, the same reference numerals as those in FIG. The suspicious person detection device 100A in FIG. 6 is different from the suspicious person detection device 100 in FIG. 1 in that an amplitude change analysis unit 110 and a reflection source determination unit 106A are used instead of the delay time change analysis unit 105 and the reflection source determination unit 106. Have.

  The amplitude change analysis unit 110 analyzes the temporal fluctuation (time change) of the reception intensity among the input delay time information and reception intensity (reception power) information. The amplitude change analysis unit 110 performs frequency conversion on temporal fluctuation (time change) of the reception intensity of the incoming wave, and sends the frequency conversion result to the reflection source determination unit 106A.

  The reflection source determination unit 106A extracts the incoming wave having a specific frequency component from the frequency conversion result of the temporal fluctuation (time change) of the received intensity of the incoming wave, thereby determining whether the reflection source is a suspicious person. Distinguish between fixed objects.

  As described in the first embodiment, with respect to the reflected wave from the human body, the reflection point slightly changes depending on the operation of heartbeat and respiration. As the reflection point changes, the amplitude (intensity) of the incoming wave reflected and received by the human body changes slightly. On the other hand, since the reflection point of a reflected wave from a fixed object such as a wall or a fixture does not change, the reception intensity of the incoming wave reflected and received from these objects does not vary. Using this feature, the reflection source determination unit 106A extracts an incoming wave having a specific frequency component based on the frequency component of the temporal fluctuation (time change) of the reception intensity of the incoming wave. The suspicious person is detected by distinguishing between the reflected wave from the object and the reflected wave from the fixed object.

  Furthermore, as described above, since the incoming wave is separated on the time axis by using a wide-band UWB pulse signal for the transmission pulse, the reflection source determination unit 106A is used when a plurality of suspicious persons exist in the area. Also, since the reflected wave for each suspicious person can be distinguished as another incoming wave, the number of suspicious persons present in the area can be counted.

  As described above, in the present embodiment, the reflection source determination unit 106A performs the reflected wave from the suspicious person based on the fluctuation of the amplitude of the incoming wave, that is, the frequency component of the temporal fluctuation (time change) of the reception intensity. Or a reflected wave from a fixed object, and detect a suspicious person.

  The inventors of the present invention performed the following measurements in order to observe the characteristics of the amplitude variation of the reflected wave from the reflector.

(1) A pulse signal is transmitted from a transmitting antenna toward a reflecting object, and a reflected wave from the reflecting object is received by a receiving antenna. The transmitting antenna and the receiving antenna are both directional horn antennas. The horn antenna constitutes a thin antenna directivity in the forward direction.
(2) Two types of reflectors, a metal plate and a human body, were used. Both reflectors were stationary.
(3) The pulse signal transmitted from the transmission antenna was a 1 GHz carrier signal, and the transmission output was 0 dBm. Moreover, the measurement was performed 10 times.

  7A and 7B are diagrams showing the measurement environment constructed in the anechoic chamber. FIG. 7A shows a measurement environment when a metal plate is used as a fixed object for the reflector. FIG. 7B shows a measurement environment when a human body is used as a reflector.

  The measurement system of FIG. 7A includes a transmission antenna 600, a reception antenna 601, and a metal plate 602. The measurement system of FIG. 7B includes a transmission antenna 600, a reception antenna 601, and a human body 603. The difference between the measurement system in FIG. 7B and the measurement system in FIG. 7A is that the reflector is changed from the metal plate 602 to the human body 603. Others are the same as FIG. 7A.

  8A and 8B show the frequency analysis results of the temporal fluctuation of the reception intensity of each reflected wave in the measurement system of FIG. 7A. FIGS. 9A and 9B show the reception intensity of each reflected wave in the measurement system of FIG. 7B. The frequency analysis result of the time fluctuation of is shown. In FIG. 8A, the reflected wave from the metal plate 602 is Fourier transformed, and the horizontal axis represents frequency and the vertical axis represents received intensity. FIG. 8A is a graph in which the measurement results of 10 times are overlapped. FIG. 8B is an enlarged view of a portion surrounded by a dotted line in FIG. 8A.

  9A, similarly to FIG. 8A, the reflected wave from the human body 603 is Fourier transformed, and the horizontal axis represents frequency and the vertical axis represents received intensity. FIG. 9B is an enlarged view of a portion surrounded by a dotted line in FIG. 9A.

  In FIG. 8B showing the result when the reflector is the metal plate 602, when attention is paid to the power of 1 GHz, there is no fluctuation in the reception intensity. On the other hand, in FIG. 9B showing the result when the reflector is the human body 603, when attention is paid to the reception intensity of 1 GHz, variation is observed in 10 measurements. As described above, even when the measurement is performed in the same measurement environment, the reception intensity of the reflected wave from the human body 603 varies. That is, by analyzing the characteristics of this variation, it is possible to detect whether the reflector is a moving body such as a human body with respiration and heartbeat, or a fixed object such as a metal plate.

  As described above, in the present embodiment, the reflection source determination unit 106A determines that the reflection source of the incoming wave is based on the change in the information on the delay time and the reception intensity of the incoming wave analyzed by the amplitude change analysis unit 110. Judgment whether it is an object or a fixed object.

  Furthermore, when the UWB signal is used for the transmission pulse by the delay profile generation unit 103 and the peak detection unit 104, since the incoming waves are separated on the time axis, when a plurality of suspicious persons exist in the area, Therefore, the number of suspicious persons present in the area can be counted.

(Embodiment 3)
FIG. 10 is a diagram showing a configuration of the suspicious person detection system according to the present embodiment. The suspicious person detection system includes a tag 700 and a base station 710.

  In the suspicious person detection system according to the present embodiment, base station 710 transmits a pulse signal for specifying a position to tag 700. The tag 700 that has received the pulse signal returns the pulse signal to the base station 710 again. The base station 710 receives this signal and specifies the position of the tag 700. Furthermore, a suspicious person who does not have a tag is detected using a received signal other than a tag reply.

  The tag 700 is carried by a human body or an object. The tag 700 has a unique identification ID (Identifier) so that it can be distinguished from other tags. ASK modulation is applied to the pulse signal transmitted from the base station 710 received by the tag 700, and retransmitted to return to the base station 710. As a method of performing ASK modulation, modulation can be performed by controlling the power source of the amplifier or by controlling the RF switch.

  The base station 710 includes the suspicious person detection device 100 according to the first embodiment, transmits a pulse signal for detecting the position of the tag and the suspicious person, and demodulates the tag ID using the pulse signal returned from the tag. , Tag position measurement and suspicious person detection. In addition, in FIG. 10, although the case where the number of tags was one was shown as an example, it is not restricted to this, A some tag may exist simultaneously.

  FIG. 11 is a diagram showing an internal configuration of base station 710 in the suspicious person detection system according to the present embodiment. In the base station 710 in FIG. 11, the same reference numerals as those in FIG. 1 are given to the same components as those in the suspicious person detection device 100 in FIG.

  The base station 710 includes a reception antenna 101, a reception radio unit 102, a delay profile generation unit 103, a peak detection unit 104, a delay time change analysis unit 105, a pulse generation unit 107, a transmission radio unit 108, a transmission antenna 109, and an ID extraction unit 711. , A distance measurement unit 712, an array antenna 713, an arrival direction measurement radio unit 714, an arrival direction measurement unit 715, and a reflection source determination unit 716.

  The array antenna 713 receives reflected waves from tags, walls, furniture, human bodies, and the like. The received signal is sent to the arrival direction measurement radio unit 714.

  The ID extraction unit 711 receives the incoming wave information extracted from the delay profile in the peak detection unit 104 and extracts a tag ID from the incoming wave.

  Here, the format of the tag ID added in the tag 700 will be described. The tag 700 asynchronously ASK modulates the tag ID. For this reason, there are cases where an incoming wave exists in time and cases where the incoming wave does not exist, and the base station 710 on the receiving side may not find the head of the tag ID. Therefore, each tag ASK-modulates the same preamble in all tags and adds it to the front of the tag ID so that the base station 710 can detect the head of the tag ID.

  The ID extraction unit 711 performs a correlation operation between the preamble pattern and the incoming wave, and determines that the portion that outputs a high correlation value is the head of the tag ID. Then, the ID extraction unit 711 extracts the tag ID by demodulating the first and subsequent portions as the tag ID. The tag ID extracted from the incoming wave information is sent to the reflection source determination unit 716. Note that information about an incoming wave to which no tag ID is added is also sent to the reflection source determination unit 716.

  The distance measurement unit 712 receives the arrival wave information output from the peak detection unit 104 and the pulse signal output from the pulse generation unit 107, and transmits the pulse signal using the arrival wave information and the pulse signal. Measure the time to receive. Since the time until the pulse signal transmitted from the base station 710 is reflected by the reflection source and received again by the base station 710 is a round-trip time, the distance measurement unit 712 uses half the time and the speed of light. To calculate the distance to the reflection source. The calculated distance between the reflection source of each incoming wave and the base station 710 is sent to the reflection source determination unit 716.

  The arrival direction measurement radio unit 714 performs amplification, band limitation, frequency conversion, AD conversion, and the like on the pulse signal received by the array antenna 713 to generate a digital baseband signal. At this time, the bandwidth of the filter used for band limitation is desirably a narrow band in consideration of ease of handling in later processing. The digital baseband signal is sent to the arrival direction measurement unit 715.

  The arrival direction measuring unit 715 calculates the arrival direction of the incoming wave with respect to the input digital baseband signal by using the directivity control of the array antenna 713 and the arrival direction estimation algorithm. As arrival direction estimation algorithms, methods such as MUSIC (Multiple SIgnal Classfication) or ESPRIT (Estimation of signal parameters via rotational invariance techniques) are generally known. The arrival direction of the incoming wave obtained by these methods is sent to the reflection source determination unit 716.

  The reflection source determination unit 716 includes the feature amount of the temporal fluctuation (delay time change) of the delay time of the arrival wave extracted by the delay time change analysis unit 105, the tag ID of the arrival wave detected by the ID extraction unit 711, The distance information between the reflection source of each incoming wave measured by the distance measuring unit 712 and the base station 710 and the arrival direction of each incoming wave calculated by the arrival direction measuring unit 715 are input. The reflection source determination unit 716 determines whether the incoming wave is a reflected wave from the tag 700 or a fixed object such as a wall or a fixture, based on the tag ID and the feature amount information of the delay time fluctuation (delay time change). Whether it is a reflected wave from the suspicious person or not. Further, the reflection source determination unit 716 identifies the position of the reflection source using the distance between the reflection source of the incoming wave and the base station 710 and the arrival direction, and determines the determination result of the reflection source and the information on the position of the reflection source. Is output.

  FIG. 12 is a flowchart showing a procedure for determining a reflection source in the reflection source determination unit 716. In FIG. 12, the reflection source determination unit 716 uses (1) a reflected wave from a tag, (2) a reflected wave from a fixed object such as a wall or a fixture, (3) a reflected wave from a suspicious person, ( 4) The case where the reflected waves from other moving bodies are divided into four will be described as an example.

  When the reflection source determination unit 716 starts processing, the process proceeds to ST800.

  In ST800, the reflection source determination unit 716 confirms whether a tag ID is added to the incoming wave. When the tag ID is added (ST800: YES), the reflection source determination unit 716 determines that the incoming wave is a reflected wave from the tag (ST801). On the other hand, when the tag ID is not added (ST800: NO), the process proceeds to ST802.

  In ST802, when the frequency analysis result of the characteristic amount of the temporal fluctuation (delay time change) of the delay time is less than 0.5 Hz (ST802: YES), the reflection source determination unit 716 converts the incoming wave to a wall or a fixture. It is determined that the reflected wave is from a fixed object (ST803). On the other hand, when the frequency analysis result of the characteristic amount of the temporal fluctuation of the delay time (delay time change) is 0.5 Hz or more (ST802: NO), the process proceeds to ST804.

  In ST804, when the frequency analysis result of the characteristic amount of the temporal fluctuation (delay time change) of the delay time is 0.5 Hz to 2 Hz (ST804: YES), the reflection source determination unit 716 determines that the incoming wave is from a suspicious person. (ST805). On the other hand, when the frequency analysis result of the characteristic amount of the temporal fluctuation of the delay time (delay time change) is 2 Hz or more (ST804: NO), the reflection source determination unit 716 determines that the reflected wave is from a moving object other than the above. (ST806).

  As described above, in the present embodiment, in the base station 710, the ID extraction unit 711 extracts the tag ID from the incoming wave, and the distance measurement unit 712 transmits the broadband pulse signal, and then the reflection source Based on the delay time until the reflected pulse signal is received, the distance to the reflection source is measured, the arrival direction measurement radio unit 714 measures the arrival direction of the received pulse signal, and the reflection source determination unit 716 As with the reflection source determination unit 106 of the first embodiment, the reflection source is the tag 700 or the wall or fixture is fixed based on the frequency component of the temporal fluctuation (delay time change) of the delay time of the incoming wave. Whether it is an object or a suspicious person is determined, and the reflection source determination unit 716 specifies the position of the reflection source based on the measured distance to the reflection source and the arrival direction.

  Thereby, when a suspicious person intrudes into the area managed by the base station 710, it is possible to detect the intrusion of a plurality of suspicious persons and specify the positions of the plurality of suspicious persons. Further, by continuously detecting the positions of a plurality of suspicious persons, the movements of the plurality of suspicious persons can be measured simultaneously.

  In addition, the reflection source determination unit 716 determines whether the reflection source of the incoming wave is a human body or a different animal (moving body) using the frequency analysis result of the temporal fluctuation (delay time change) of the delay time of the incoming wave. Can be determined. In addition, by using these determination results, it is possible to detect whether a human is alive, for example, during a disaster.

  In the above description, the suspicious person detection system including the base station 710 on which the suspicious person detection device 100 described in the first embodiment is mounted has been described. However, the suspicious person detection described by the base station 710 in the second embodiment is described. Even when the device 100A is mounted, the suspicious person detection system can obtain the same effect as described above.

  Hereinafter, a case where the base station 710 is equipped with the suspicious person detection device 100A described in the second embodiment will be described.

  FIG. 13 is a diagram illustrating an internal configuration of a base station 710A on which the suspicious person detection device 100A described in the second embodiment is mounted. In the base station 710A of FIG. 13, the same components as those of the base station 710 of FIG. A base station 710A in FIG. 13 includes an amplitude change analysis unit 110 and a reflection source determination unit 716A in place of the delay time change analysis unit 105 and the reflection source determination unit 716 with respect to the base station 710 in FIG.

  The reflection source determination unit 716 </ b> A includes a feature amount of temporal fluctuation (time change) of the received intensity of the incoming wave extracted by the amplitude change analysis unit 110, the tag ID of the incoming wave detected by the ID extraction unit 711, and a distance measurement unit 712. The distance information between the reflection source of each incoming wave measured in step 710A and the base station 710A and the arrival direction of each incoming wave calculated by the arrival direction measuring unit 715 are input. The reflection source determination unit 716A determines whether the incoming wave is a reflected wave from the tag 700 or a fixed object such as a wall or a fixture, based on the feature amount information of the tag ID and the temporal fluctuation (time change) of the reception intensity. Whether the reflected wave is a reflected wave from a suspicious person. Further, the reflection source determination unit 716A specifies the position of the reflection source using the distance from the reflection source and the arrival direction, and outputs the determined reflection source determination result and information on the position of the reflection source.

  As described above, in the base station 710A, the reflection source determination unit 716A is based on the frequency component of the temporal fluctuation (time change) of the reception intensity of the incoming wave, similarly to the reflection source determination unit 106A of the second embodiment. Then, it is determined whether the reflection source is the tag 700, a fixed object such as a wall or a fixture, or a moving body with breathing and heartbeat of a suspicious person, and the reflection source determination unit 716A determines the measured distance and arrival direction. Based on this, the position of the reflection source was specified.

  Thus, when a suspicious person enters the area managed by the base station 710A, it is possible to detect the intrusion of a plurality of suspicious persons and to specify the positions of the plurality of suspicious persons. Further, by continuously detecting the positions of a plurality of suspicious persons, the movements of the plurality of suspicious persons can be measured simultaneously.

  Further, the reflection source determination unit 716A determines whether the reflection source of the incoming wave is a human body or a different animal (moving body) by using the frequency analysis result of the temporal fluctuation (time change) of the reception intensity of the incoming wave. be able to. In addition, by using these determination results, it is possible to detect whether a human is alive, for example, during a disaster.

  The present invention is useful for a security system using a wide-band pulse signal, for example, a security system using a positioning technique performed using a wireless tag. Furthermore, it can be applied to medical fields such as a telemedicine management system.

100, 100A Suspicious person detection device 101, 601 Reception antenna 102 Reception radio unit 103 Delay profile generation unit 104 Peak detection unit 105 Delay time change analysis unit 106, 106A Reflection source determination unit 107 Pulse generation unit 108 Transmission radio unit 109 Transmission antenna 110 Amplitude change analysis unit 500, 502 Antenna 300, 710, 710A Base station 501, 503, 603 Human body 600 Transmission antenna 602 Metal plate 700 Tag 711 ID extraction unit 712 Distance measurement unit 713 Array antenna 714 Arrival direction measurement radio unit 715 Arrival direction measurement 716, 716A Reflection source determination unit

Claims (5)

A transmission means for transmitting a wide-band pulse signal at predetermined intervals;
Receiving means;
Generating means for generating a delay profile of the received signal received by the receiving means at each predetermined interval;
Detecting means for detecting, for each reflection source, an incoming wave in which the broadband pulse signal is reflected by a reflection source by detecting a peak of the delay profile;
Analyzing means for analyzing, for each reflection source, a frequency component of a temporal fluctuation of a delay time from when the transmitting means transmits the broadband pulse signal until the receiving means receives the incoming wave;
Determination means for determining whether the reflection source is a moving object or a fixed object based on the frequency component for each reflection source;
A suspicious person detection device comprising: A transmission means for transmitting a wide-band pulse signal at predetermined intervals;
Receiving means;
Generating means for generating a delay profile of the received signal received by the receiving means at each predetermined interval;
Detecting means for detecting, for each reflection source, an incoming wave in which the broadband pulse signal is reflected by a reflection source by detecting a peak of the delay profile;
Analyzing means for analyzing the frequency component of temporal fluctuation of the received intensity of the incoming wave for each of the reflection sources;
Determination means for determining whether the reflection source is a moving object or a fixed object based on the frequency component for each reflection source;
A suspicious person detection device comprising: The suspicious person detection device according to claim 1 or 2,
A distance measuring unit that measures a distance from the reflection source based on a delay time from when the transmitting unit transmits the broadband pulse signal to when the receiving unit receives the incoming wave;
Direction of arrival measurement means for measuring the direction of arrival of the received arrival wave, and
The determination means, based on the measured distance and the arrival direction, further, the suspicious person detection device for specifying the position of the reflection source;
Receiving means for receiving the broadband pulse signal transmitted from the suspicious person detection device;
Adding means for adding a tag ID unique to the device to the received wide-band pulse signal;
A transmission means for amplifying and transmitting the pulse signal with the tag ID added thereto;
Suspicious person detection system comprising. A wide-band pulse signal is transmitted at predetermined intervals,
Generate a delay profile of the received signal at each predetermined interval,
By detecting the peak of the delay profile, an incoming wave in which the broadband pulse signal is reflected by a reflection source is detected for each reflection source,
Analyzing the frequency component of the temporal fluctuation of the delay time from the transmission of the pulse signal to the reception of the incoming wave for each reflection source,
Based on the frequency component for each of the reflection sources, it is determined whether the reflection source is a moving object or a fixed object.
Suspicious person detection method. A wide-band pulse signal is transmitted at predetermined intervals,
Generate a delay profile of the received signal at each predetermined interval,
By detecting the peak of the delay profile, an incoming wave in which the broadband pulse signal is reflected by a reflection source is detected for each reflection source,
Analyzing the frequency component of temporal fluctuation of the received intensity of the incoming wave for each reflection source,
Based on the frequency component for each of the reflection sources, it is determined whether the reflection source is a moving object or a fixed object.
Suspicious person detection method.

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