JP7182245B2 - Radio wave sensor and radio wave detection method - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a radio wave sensor and a radio wave detection method, and more particularly to a radio wave sensor and a radio wave detection method that transmit radio waves to a mobile body and receive reflected waves of the transmitted radio waves to detect the presence or absence of the mobile body.

2. Description of the Related Art Conventionally, there has been known a lighting control system in which a human sensor and lighting are provided together, the presence or absence of a human body within a certain range is detected by the human sensor, and the lighting is turned on for a certain period of time when a human body is detected. For example, Patent Literature 1 discloses a passive sensor that detects a temperature change due to human movement within a detection area and outputs a detection signal. point out. Therefore, by using an active sensor that itself transmits and receives signals and detects the presence or absence of an object based on the transmitted signal and the received signal, it is possible to detect the presence or absence of an object over a long distance without being affected by temperature changes. Says. As such an active sensor, for example, a radio wave sensor that detects the presence or absence of a moving object based on a Doppler shift occurring in reflected waves is known.

In Patent Document 2, when radio waves are radiated at the same timing using two antennas and the reflected waves are received by the respective antennas, the radiated waves radiated from one of the antennas interfere with the radiated waves radiated from the other. point out that Therefore, it is described that one antenna is provided with two feeding points of different methods, and mutually orthogonally polarized waves are transmitted and received at the same time, thereby preventing mutual interference waves.

Japanese Unexamined Patent Application Publication No. 2011-23307 JP 2011-89864 A

By using a radio wave sensor, it is possible to detect the presence or absence of an object over a long distance. However, radio waves may penetrate the walls of a building and detect the presence or absence of an object beyond the wall. For example, in the case of a system that turns on emergency staircase lighting based on the detection of a human body by a radio wave sensor, it detects the presence or absence of a human body beyond the wall that separates the area of the emergency staircase, which is the detection range of the human body, and turns on unnecessary lighting. there is a possibility. Therefore, there is a demand for a radio wave sensor and a radio wave detection method that can correctly determine the presence or absence of a moving object within a predetermined detection range.

A radio wave sensor according to the present disclosure is a radio wave sensor that transmits radio waves to a predetermined detection range, receives radio waves that are reflected by a moving body in the transmitted radio waves, and detects the presence or absence of a moving body within the detection range. an antenna unit that transmits and receives a first polarized wave and a second polarized wave that are different in polarization from each other; a polarization switching unit that switches between transmission and reception of the first polarized wave and transmission and reception of the second polarized wave; and a polarization switching unit. A switching signal output unit that outputs a polarization switching signal that instructs switching between the first polarized wave and the second polarized wave at a predetermined polarization switching cycle, a high frequency circuit that performs processing related to the transmission and reception signals of the antenna unit, A signal that is the difference between the received signal level of the first polarized wave and the received signal level of the second polarized wave when the received signal of the first polarized wave and the received signal of the second polarized wave are detected by being connected to a high-frequency circuit. Regarding the level difference, using a criterion set according to the environment in which the radio wave sensor is installed, if the signal level difference is less than the criterion, it is determined that there is a moving object within the detection range, and the first deviation is detected. a determination unit that determines that there is no moving object within the detection range when neither the received signal of the second polarized wave nor the received signal of the second polarized wave is detected and when the signal level difference is equal to or greater than a determination criterion.

A radio wave detection method according to the present disclosure transmits radio waves to a predetermined detection range, receives radio waves reflected by a moving object from the transmitted radio waves, and detects the presence or absence of a moving object within the detection range. wherein a first polarized wave and a second polarized wave having different polarizations are transmitted by switching between the first polarized wave and the second polarized wave at a predetermined polarization switching cycle, and a received signal of the first polarized wave is transmitted. And when the received signal of the second polarized wave is detected, the signal level difference, which is the difference between the received signal level of the first polarized wave and the received signal level of the second polarized wave, depending on the environment in which the radio wave sensor is installed If the signal level difference is less than the criterion, it is determined that there is a moving object within the detection range, and the received signal of the first polarized wave and the received signal of the second polarized wave are If not detected, or if the signal level difference is equal to or greater than the criterion, it is determined that there is no moving object within the detection range.

According to the radio wave sensor and the radio wave detection method configured as described above, it is possible to correctly determine the presence or absence of a moving object within a predetermined detection range.

It is a figure which shows the detection state of the moving body in the emergency staircase in which the radio wave sensor which concerns on embodiment is installed. 1 is a block diagram showing the configuration of a radio wave sensor according to an embodiment; FIG. FIG. 10 is a diagram showing an example in which the TE wave and the TM wave respectively enter the wall from the air and pass through the wall when the first polarized wave of the radio wave is the TE wave and the second polarized wave is the TM wave. FIG. 3 is a diagram showing an example of the relationship between the incident angle and the transmission coefficient when TE waves and TM waves of radio waves are incident on an object from the air. FIG. 10 is a diagram showing an example of determination of presence/absence of a moving object in the radio wave sensor according to the embodiment; 4 is a flow chart showing the procedure of the radio wave detection method according to the embodiment;

Embodiments of the present disclosure will be described in detail below with reference to the drawings. The frequencies and the like described below are examples for explanation, and can be changed as appropriate according to the specifications of the radio wave sensor. In the following, corresponding elements in all the drawings are given the same reference numerals, and overlapping descriptions are omitted.

FIG. 1 is a diagram showing a lighting control system 10 using radio wave sensors 20. As shown in FIG. The lighting control system 10 is a system for controlling the lighting and extinguishing of emergency lights 18 provided at appropriate locations on the wall surface 14 facing the emergency stairs 12 and the wall surface 16 at the end of the landing 15 on each floor of the emergency stairs 12. The emergency light 18 has a lighting circuit that controls it to turn on, off, or to a dim lighting state that is a power saving state. Since the emergency staircase 12 is a staircase that is not normally used, the emergency light 18 is turned off or is in a power-saving state. do. The lighting control system 10 uses the radio wave sensor 20 to determine whether or not the emergency light 18 is turned on. When it is determined that there is no person 8, the emergency light 18 is turned off or in a power saving state, and when it is determined that the person 8 is present, the emergency light 18 is brightly lit.

The emergency staircase 12 is provided in a space between a wall surface 14 and a wall surface 16 of the building. The space between the wall surface 14 and the wall surface 16 is the area space of the emergency stairs 12 in which the radio wave sensor 20 is arranged, and the radio wave sensor 20 detects the presence or absence of the person 8 with respect to turning on and off the emergency light 18. Since it is the set range, it is called a predetermined detection range 30 . For example, even if there is a person 9 on the other side of the wall 17 having the wall surface 16, there is no need to turn on the emergency light 18. is.

The radio wave sensor 20 transmits radio waves 22 within a predetermined detection range 30, receives radio waves 24 that are reflected by a person 8 who is a moving object, and detects a person 8 who is a moving object within the detection range 30. It is an active sensor that detects the presence or absence of 8. A person 8 using the emergency staircase 12 must be cautious when going up and down the emergency staircase 12 due to an emergency situation or the like. type sensor.

The Doppler method is a method of determining the moving speed of a moving object based on the frequency difference between the frequency of the radio wave 22 transmitted to the moving object and the frequency of the radio wave 24 reflected from the moving object. If the frequency difference signal is called the Doppler signal, when there is no moving object, the amplitude of the Doppler signal is the background noise level, and when there is a moving object, the frequency difference Doppler signal related to the speed of the moving object is appears and its amplitude is above the noise level. Therefore, the radio wave sensor 20 calculates a Doppler signal from the transmitted radio wave 22 and the received radio wave 24, and determines the amplitude of the Doppler signal based on a predetermined criterion, thereby detecting the presence or absence of the person 8 who is a moving object on the emergency stairs 12. detectable.

By the way, the radio wave 23 transmitted from the radio wave sensor 20 may pass through the wall 17 that separates the inside of the detection range 30 and the outside of the detection range 32 that is not inside the detection range 30 . In this case, the radio wave 23 transmitted through the wall 17 is reflected by the person 9 who is a moving object outside the detection range 32, and when the radio wave sensor 20 receives the reflected radio wave 25, the person 9 who is a moving object is present. , the emergency light 18 may be turned on due to an erroneous detection. The radio wave sensor 20 has the configuration shown in FIG. 2 in order to prevent such erroneous detection.

FIG. 2 is a block diagram showing the configuration of the radio wave sensor 20. As shown in FIG. The radio wave sensor 20 includes an antenna section 40 , a high frequency circuit 50 , a control circuit 60 and a polarization switching section 70 . In FIG. 2, thick lines are high-frequency lines 82, 84, 86 through which high-frequency signals pass, and thin lines are general signal lines 90, 92, 94. In FIG. Since high-frequency signals pass through conductors and cause loss, it is preferable that the high-frequency lines 82, 84, 86 be as short as possible.

The antenna unit 40 is an antenna capable of independently transmitting and receiving a first polarized wave and a second polarized wave, which are polarized waves different from each other. The first polarized wave and the second polarized wave need only have different polarization directions, and may not have an orthogonal polarization relationship. Such an antenna unit 40 can be composed of a set of antennas in which a horizontally polarized wave antenna and a vertically polarized wave antenna are arranged in an angular relationship in which the mutual transmission and reception directions are not parallel.

If the transmitting and receiving directions are orthogonal to each other, it can be configured with one microstrip antenna. For example, it is possible to use a microstrip antenna which is a planar antenna including a dielectric substrate, a radiating element and a ground conductor plate printed and wired on both sides of the substrate, and two feeding lines connected to the radiating element and having a mutually orthogonal arrangement relationship. can. The two feed lines are a horizontal feed line for horizontal polarization and a vertical feed line for vertical polarization. The horizontal feed line and the vertical feed line are provided along a direction orthogonal to each side through the center of each of the four sides of the square radiating element of the planar antenna that are orthogonal to each other. The horizontal feed line and the vertical feed line are provided at positions deviated from the center point of the square radiating element toward the edge side of the side.

A radio wave is an electromagnetic wave, and an electromagnetic wave is composed of an electric field and a magnetic field that oscillate in mutually orthogonal directions. In an electromagnetic wave, when the direction of oscillation of the electric field or magnetic field is constant, it is called a linearly polarized wave, and the plane containing the direction of oscillation of the electric field and the propagation direction of the electromagnetic wave is called the plane of polarization. When the polarization plane is horizontal with respect to the ground, it is horizontal polarization, and when it is vertical, it is vertical polarization. The horizontally polarized wave is called a TE (Transverse Electric) wave because the electric field oscillates horizontally, and the vertically polarized wave is called a TM (Transverse Magnetic) wave because the magnetic field oscillates horizontally. Therefore, the horizontal feed line is used as a feed line for transmitting and receiving TE waves, and the vertical feed line is used as a feed line for transmitting and receiving TM waves. The antenna section 40 composed of one microstrip antenna will be described below.

The antenna section 40 in FIG. 2 is a planar microstrip antenna including two feeder lines. In FIG. 2, a planar antenna is modeled as a square radiating element, and a horizontal feed line 42 and a vertical feed line 44 are shown, which are provided on respective side edges of mutually orthogonal sides. TM waves transmitted and received by the vertical feed line 44 are indicated by solid lines, and TE waves transmitted and received by the horizontal feed line 42 are indicated by dashed lines. In the following, the first polarized wave is horizontal polarized wave, ie TE wave, and the second polarized wave is vertical polarized wave, ie TM wave.

The high-frequency circuit 50 is a circuit that performs processing related to transmission/reception signals. The high-frequency circuit 50 includes a transmission section 52 that outputs transmission radio waves of a predetermined frequency, a reception section 54 that receives reception radio waves, a detection circuit 56 that measures the reception power level, which is the power level of the reception radio waves, and a Doppler processing section 58 . include.

The predetermined frequency of the transmission radio wave output by the transmission section 52 is approximately 24 GHz. The receiver 54 is a circuit that receives TE waves and TM waves and performs signal processing on the received waves. The detection circuit 56 is a circuit that measures the power level of the received TE wave and TM wave and transmits the measured data to the control circuit 60 via the signal line 90 .

The Doppler processing unit 58 converts the frequency difference signal, which is the difference between the transmission frequency of the TE wave transmitted from the horizontal feeder 42 and the reception frequency of the TE wave received by the horizontal feeder 42, into a TE wave Doppler signal. Ask. The obtained amplitude of the TE wave Doppler signal is transmitted to the control circuit 60 via the signal line 90 . Similarly, a frequency difference signal, which is the difference between the transmission frequency of the TM wave transmitted from the vertical feeder 44 and the reception frequency of the TM wave received by the vertical feeder 44, is obtained as the Doppler signal of the TM wave. The obtained amplitude of the TM wave Doppler signal is transmitted to the control circuit 60 via the signal line 90 .

The control circuit 60 includes a switching signal output section 62 that outputs a polarization switching signal that instructs the polarization switching section 70 to switch between the first polarization and the second polarization at a predetermined polarization switching cycle. The polarization switching signal is output to the polarization switching section 70 so that the antenna section 40 constantly switches between transmission and reception of the TE wave and transmission and reception of the TM wave repeatedly at the polarization switching cycle. The polarization switching cycle is set to a cycle within the time width in which the first polarized wave and the second polarized wave can be transmitted and received by the person 8 who is the same moving object. If the polarization switching period is too long, the TE wave is transmitted to and received from the person 8, but the TM wave is transmitted and received to and from a place where no one is present. A possibility arises. The frequency corresponding to the moving speed of the person 8 on the emergency stairs 12 is several tens of Hz, although it depends on the situation. cannot be detected. Preferably, the polarization switching period is set to less than 1 ms.

Control circuit 60 further includes determination unit 64 . The determination unit 64 determines whether or not there is a person 8 who is a mobile object within the detection range 30 . Judgment is performed in two steps.

The first step is to determine whether or not there is a TE wave received signal and a TM wave received signal. If there is no TE wave reception signal or TM wave reception signal, no reflected wave is returned even if the radio wave is transmitted. . The presence or absence of the received TE wave signal and the received TM wave signal is determined based on the presence or absence of the Doppler signal of the TE wave and the Doppler signal of the TM wave in order to avoid the influence of the reflected wave from the wall surface 16 . Hereinafter, the Doppler signal of the TE wave, which is the first polarized wave, will be referred to as the first Doppler signal, and the Doppler signal of the TM wave, which is the second polarized wave, will be referred to as the second Doppler signal. The first Doppler signal and the second Doppler signal are obtained in the Doppler processing section 58 of the high frequency circuit 50 . A criterion for determining the presence or absence of a Doppler signal can be determined based on a predetermined noise level in the Doppler signal. If the amplitude level of the first Doppler signal and the amplitude level of the second Doppler signal are less than the noise level in the Doppler signal, it is determined that there is no TE wave received signal and no TM wave received signal.

If there is a TE wave received signal and a TM wave received signal, the process proceeds to the second step. In the second step, a signal level difference, which is the difference between the received signal level of the TE wave and the received signal level of the TM wave within the same polarization switching cycle, is used. As the signal level difference, an amplitude level difference, which is the difference between the amplitude level of the first Doppler signal obtained by the Doppler processing unit 58 and the amplitude level of the second Doppler signal, is used. Since the amplitude of the Doppler signal increases as the power level of the radio wave increases, instead of the amplitude level difference of the Doppler signal, the received power level of the TE wave and the received power level of the TM wave measured by the detector circuit 56 are used. A power level difference, which is the difference between .

If the signal level difference within the same polarization switching cycle is less than a predetermined criterion, the determination unit 64 determines that the person 8 who is a moving object is present within the detection range 30 . On the other hand, if the signal level difference within the same polarization switching cycle is equal to or greater than the predetermined determination criterion, the determination unit 64 determines that the person 9, who is a moving object, located outside the detection range 32 has been erroneously detected. It is determined that there is no person 8 who is a mobile body within the range 30 . The criterion is set in advance according to the environment in which the radio wave sensor 20 is installed.

Therefore, when the determination unit 64 detects the received signal of the first polarized wave and the received signal of the second polarized wave, and the signal level difference within the same polarization switching cycle is less than a predetermined determination criterion, the detection It is determined that there is a person 8 who is a mobile object within the range 30 . In addition, when the determination unit 64 does not detect the received signal of the first polarized wave and the received signal of the second polarized wave, and when the signal level difference is equal to or greater than a predetermined determination criterion, determines that there is no moving object. A specific example of determining the presence or absence of people 8 and 9, which are moving bodies, will be described later.

When the determination unit 64 determines that the person 8 who is a mobile body is present within the detection range 30, a lighting instruction signal for bright lighting is transmitted to the lighting circuit of the emergency light 18 via the signal line 94. . When the determination unit 64 determines that there is no person 8 who is a mobile body within the detection range 30, a signal is output to the emergency light 18 to turn it off or to turn it into a dim lighting state in a power-saving state.

As the control circuit 60, a microprocessor suitable for mounting on the radio wave sensor 20 integrated with the emergency light 18 is used.

The polarization switching unit 70 is switching means for switching the connection destination of the high-frequency circuit 50 to either the horizontal feed line 42 or the vertical feed line 44 of the antenna unit 40 based on the polarization switching signal. The polarization switching section 70 includes a horizontal polarization switching section 72 for the horizontal feed line 42 , a vertical polarization switching section 74 for the vertical feed line 44 , and a circuit connection section 76 for the high frequency circuit 50 .

The high-frequency line 82 connects between the horizontal feed line 42 and the horizontal polarization switching section 72, the high-frequency line 84 connects between the vertical feed line 44 and the vertical polarization switching section 74, and the high-frequency line 86 connects , connect between the high-frequency circuit 50 and the circuit connection portion 76 .

The effects of the above configuration, particularly the function of the control circuit 60, will be described in more detail with reference to FIGS. 3 to 5. FIG.

FIG. 3 is a diagram showing an example in which the TE wave and the TM wave respectively enter the wall surface 16 from the air and pass through the wall 17. As shown in FIG. In FIG. 3 , the solid line and broken line indicate the traveling direction in which the radio wave travels through the air in the detection range 30 toward the wall surface 16 , passes through the wall 17 , and exits to the other side of the wall 17 . A solid line indicates the traveling direction of the TM wave, and a dashed line indicates the traveling direction of the TE wave. An incident angle θ, which is the angle at which the traveling direction of the radio wave is incident on the wall surface 16, is the angle between the normal line of the wall surface 16 and the traveling direction of the radio wave. Assuming that the wall 17 is erected vertically to the ground surface, the vector direction of the electric field of the horizontally polarized TE wave is horizontal to the ground surface. In FIG. 3, the dashed line indicating the traveling direction of the TE wave is indicated by a mark with a black circle inside a circle. The vector direction of the electric field of the vertically polarized TM wave is perpendicular to the ground surface, but since the traveling direction of the radio wave is tilted at the incident angle θ with respect to the ground, it is tilted by the incident angle θ from the ground surface. In FIG. 3, this is indicated by an arrow mark perpendicular to the solid line indicating the traveling direction of the TM wave.

The characteristics of the TE wave and TM wave traveling through the air in the detection range 30, entering the wall surface 16 of the wall 17 having a dielectric constant greater than that of the air, and passing through the wall 17 are defined by the well-known Snell's law. can be calculated using FIG. 4 is a diagram showing an example of calculation results. The horizontal axis is the incident angle θ, and the vertical axis is the transmission coefficient. In the calculation, the dielectric constant of glass was used assuming that the wall 17 was a glass wall. When the incident angle θ is 0 degrees, both the TE wave and the TM wave are incident perpendicularly to the wall surface 16, so there is no difference in the plane of polarization and the transmission coefficients are the same. There is a difference between the transmission coefficient of the .TM. In the example of FIG. 4, {TM wave transmission coefficient}>{TE wave transmission coefficient} when the incident angle θ is about 15 degrees or more.

Considering the reflection of radio waves from a person 9 who is a moving object shown in FIG. It exits and is reflected from a person 9 who is a moving body. Radio waves reflected from a person 9 who is a moving object travel in the direction opposite to the direction of incidence in the air outside the detection range 32, pass through the wall 17, go out into the air within the detection range 30, and reach the radio wave sensor 20. return. Therefore, the radio wave penetrates the wall 17 twice. When TM waves and TE waves are separately used as radio waves, {transmission coefficient of TM waves}>{transmission coefficient of TE waves} when the incident angle θ is about 15 degrees or more. The signal level of the TE wave as is lower than the signal level of the TM wave.

On the other hand, the transmitted wave and the reflected wave from the person 8, who is a moving object on the emergency stairs 12 within the detection range 30, both pass only through the air. is the same as the signal level of the TM wave.

As a first step, the determination unit 64 of the control circuit 60 of the radio wave sensor 20 determines the presence or absence of the received signal of the TE wave and the received signal of the TM wave. In the first stage, if it is determined that there is a TE wave received signal and a TM wave received signal, the process proceeds to the second stage. In the second step, the signal level difference, which is the difference between the received signal level of the TE wave and the received signal level of the TM wave, is used. As described above, for the person 8 who is a mobile object on the emergency stairs 12 within the detection range 30, the received signal level of the TE wave and the received signal level of the TM wave are the same, so the signal level difference is zero. . On the other hand, for the person 9 who is a moving object outside the detection range 32, the received signal level of the TE wave is lower than the received signal level of the TM wave, so the signal level difference does not become zero. By using this, it is possible to distinguish between the person 8 who is a moving object on the emergency stairs 12 within the detection range 30 and the person 9 who is a moving object outside the detection range 32 .

FIG. 5 is a diagram showing an example of determination by the determining unit 64 regarding presence/absence of persons 8 and 9 who are moving objects within the detection range 30 and outside the detection range 32, respectively. In FIG. 5, CASE 1, CASE 2, CASE 3, and CASE 4 indicate four combinations of detection range 30, detection range 32, and people 8 and 9, which are moving bodies. (a) in each CASE is a diagram showing where people 8 and 9 who are moving bodies are.

(b) is a diagram showing the received signal level of the TE wave and the received signal level of the TM wave, which are used for the first-stage determination in the determining section 64, respectively, with a dashed line and a solid line. The horizontal axis is time, and the vertical axis is the amplitude _ATE of the first Doppler signal and the amplitude _ATM of the second Doppler signal. _A0 on the vertical axis is a predetermined noise level related to Doppler amplitude, which is a criterion for determining the presence or absence of a received signal.

(c) is a diagram showing a signal level difference, which is the difference between the received signal level of the TE wave and the received signal level of the TM wave, which is used for the second stage determination in the determination section 64, with a thick solid line. The horizontal axis is time, and the vertical axis is the signal level difference ΔA=(A _TM −A _{TE )} , which is the difference between the amplitude A _TE of the first Doppler signal and the amplitude ATM of the second Doppler signal. (ΔA) ₀ on the vertical axis is a predetermined criterion for the Doppler signal level difference.

(d) is a column showing the content of (a), and (e) is a column showing the state of the emergency light 18 based on the judgment result of the judging section 64 .

FIG. 6 shows radio wave detection for detecting the presence or absence of a person 8 who is a moving object within the detection range 30 by transmitting radio waves to a predetermined detection range 30 and receiving the radio waves reflected by the moving object. 4 is a flow chart showing the steps of the method; The radio wave sensor 20 switches between the first polarized wave and the second polarized wave having different polarized waves at a predetermined polarization switching period and transmits the polarized waves (S10). This process proceeds as follows. That is, the polarization switching signal is output to the polarization switching section 70 from the switching signal output section 62 of the control circuit 60 in the radio wave sensor 20 . Based on the polarization switching signal, the polarization switching section 70 switches the connection destination of the high-frequency circuit 50 to either the horizontal feeder line 42 or the vertical feeder line 44 of the antenna section 40 . Switching is performed at a polarization switching cycle of 1 ms, for example. The transmission section 52 of the high frequency circuit 50 outputs transmission radio waves with a transmission cycle of approximately 24 GHz. In the polarization switching section 70 , the TE wave as the first polarized wave is transmitted from the antenna section 40 while the circuit connection section 76 for the high frequency circuit 50 is connected to the horizontal feeder 42 . While the circuit connection portion 76 for the high frequency circuit 50 is connected to the vertical feeder 44, the antenna portion 40 transmits the TM wave as the second polarized wave.

Next, it is determined whether or not there is a person 8 who is a mobile object within the detection range 30 . This determination is performed in two steps. The first step is to determine whether or not there is a TE wave received signal and a TM wave received signal. The presence or absence of the received signal of the TE wave and the received signal of the TM wave is determined by the amplitude level _ATE of the first Doppler signal that is the Doppler signal of the TE wave and the amplitude level ATM of the second Doppler signal that is the Doppler signal of _{the TM wave} , The presence or absence of the Doppler signal is compared with a predetermined criterion _A0 . Criterion A ₀ is a predetermined noise level in terms of Doppler amplitude.

That is, in the first step, it is determined whether or not {(A _TE , _ATM )≧A ₀ (S12). The amplitude level _ATE of the first Doppler signal and the amplitude level _ATM of the second Doppler signal are obtained by signal processing of the received signal received by the receiving section 54 of the high frequency circuit 50 by the Doppler processing section 58 and the determination section 64 of the control circuit 60. output to The procedure of S<b>12 is executed by the determination unit 64 . If the determination in S12 is affirmative, the process proceeds to S14 as a determination of the second stage. If the determination in S12 is negative, since there is no reflected wave even if the radio wave is transmitted, it is determined that there is no moving person 8 within the detection range 30, and the process proceeds to S16.

If the determination in S12 is affirmative and there are the received signal of the TE wave and the received signal of the TM wave, the level of the received signal of the TE wave and the received signal of the TM wave within the same polarization switching period are determined as the second stage determination. It is determined whether or not the signal level difference, which is the difference from the level, is less than a predetermined criterion. As the received signal level of the TE wave and the received signal level of the TM wave, the amplitude level _ATE of the first Doppler signal and the amplitude level _ATM of the second Doppler signal can be used. In this case, it is determined whether or not [{ΔA=(A _TM −A _TE )}≧(ΔA) ₀ ] (S14). (ΔA) ₀ is the predetermined criterion for the Doppler signal level difference. The procedure of S<b>12 is executed by the determination unit 64 .

If the determination in S14 is affirmative, it means that the moving person 9 outside the detection range 32 has been erroneously detected. move on. If the determination in S14 is negative, it is determined that the person 8 who is a moving object is present within the detection range 30, and the process proceeds to S20.

In this way, when the received signal of the first polarized wave and the received signal of the second polarized wave are detected by the two-stage determination, and the signal level difference within the same polarization switching cycle is less than the predetermined determination criterion Then, it is determined that there is a person 8 who is a mobile object within the detection range 30 (S20). When neither the received signal of the first polarized wave nor the received signal of the second polarized wave is detected, and when the signal level difference is equal to or greater than the predetermined criterion, there is no moving object within the detection range 30. (S16). In S20, when it is determined that the person 8 who is a moving object is within the detection range 30, a lighting instruction signal for bright lighting is transmitted to the lighting circuit of the emergency light 18 via the signal line 94 ( S22). When it is determined in S16 that there is no person 8 who is a moving body within the detection range 30, a signal is output to the emergency light 18 to turn it off or to turn it into a dim lighting state for power saving (S18).

Returning to FIG. 5, CASE 1 is a case where there is no person 8 who is a moving object within the detection range 30 and there is no person 9 who is a moving object outside the detection range 32 . In this case, in (b), both the amplitude _{A_TE} of the first Doppler signal and the amplitude _ATM of the second Doppler signal are less than _{A_0} , and the determination in S12 is negative in the flowchart of FIG. Therefore, the determination unit 64 determines that there is no person 8 who is a moving object within the detection range 30, and turns off the emergency light 18 or puts it into a power saving state.

CASE 2 is a case where a moving person 8 is present within the detection range 30 but there is no moving person 9 outside the detection range 32 . In this case, in (b), the amplitude A _TE of the first Doppler signal and the amplitude _ATM of the second Doppler signal are both A ₀ or more, but in (c) ΔA=(A _TM −A _TE ) is (ΔA) becomes less than ₀ . In the flowchart of FIG. 6, the determination of S12 is affirmative, and the determination of S14 is negative. Therefore, the determination unit 64 determines that "a person 8 who is a moving object is present within the detection range 30" and lights the emergency light 18 brightly.

CASE 3 is the state shown in FIG. 1 when there is a person 8 who is a mobile body within the detection range 30 and a person 9 who is a mobile body is also outside the detection range 32 . In this case, in (b), the amplitude A _TE of the first Doppler signal and the amplitude _ATM of the second Doppler signal are the Doppler signal from the moving object 8 within the detection range 30 and the Doppler signal from the moving object outside the detection range 32 . It becomes the amplitude of the signal on which the Doppler signal from the person 9 who is a moving body is superimposed. Since the Doppler signal from the person 9 who is a moving object outside the detection range 32 passes through the wall 17 twice, the person who is a moving object within the detection range 30 which is the area where the radio wave sensor 20 is arranged much smaller than the Doppler signal from 8. Therefore, the amplitude A _TE of the superimposed first Doppler signal and the amplitude _ATM of the superimposed second Doppler signal in (b) are substantially the first Doppler signal from the moving person 8 within the detection range 30 . One may consider the amplitude of the signal _ATE and the amplitude _ATM of the second Doppler signal. Therefore, ΔA=(A _TM −A _TE ) in (c) is almost the same as in CASE 2, and (ΔA) is less than ₀ . In the flowchart of FIG. 6, the determination of S12 is affirmative, and the determination of S14 is negative. Therefore, the determination unit 64 determines that "a person 8 who is a moving object is present within the detection range 30" and lights the emergency light 18 brightly.

CASE 4 is a case where there is no moving person 8 within the detection range 30 but there is a moving person 9 outside the detection range 32 . In this case, in (b), the amplitude _ATE of the first Doppler signal and the amplitude _ATM of the second Doppler signal are both _A0 or more. Then, ΔA=(A _TM −A _TE) in (c) becomes (ΔA) ₀ or more due to the difference between the transmission coefficient of the TE wave and the transmission coefficient of the TM wave when passing through the wall 17 . In the flowchart of FIG. 6, the determination of S12 is affirmative, and the determination of S14 is also affirmative. Therefore, the determination unit 64 determines that there is no person 8 who is a mobile object within the detection range 30, and turns off the emergency light 18 or puts it into a power saving state.

According to the radio wave sensor 20 configured as described above, even if the person 9 who is a mobile body exists outside the detection range 32 , the presence or absence of the person 8 who is a mobile body within the predetermined detection range 30 can be determined correctly. As a result, the lighting state of the emergency light 18 can be appropriately set to be off or in a power saving state, and to be turned on, thereby eliminating useless lighting due to erroneous detection.

8, 9 person (moving object), 10 lighting control system, 12 emergency stairs, 14, 16 wall, 15 landing, 17 wall, 18 emergency light, 20 radio wave sensor, 22, 23, 24, 25 radio wave, 30 detection Range 32 Out of detection range 40 Antenna section 42 Horizontal feeding line 44 Vertical feeding line 50 High frequency circuit 52 Transmitting section 54 Receiving section 56 Detection circuit 58 Doppler processing section 60 Control circuit 62 Switching signal output Section 64 Determining Section 70 Polarization Switching Section 72 Horizontal Polarization Switching Section 74 Vertical Polarization Switching Section 76 Circuit Connection Section 82, 84, 86 High Frequency Line 90, 92, 94 Signal Line.

Claims (3)

Installed on a first wall surface, facing the first wall surface, incident on the second wall surface with respect to a predetermined detection range that is a spatial region between the second wall surface of the radio wave transparent wall A radio wave sensor that transmits radio waves with an angle of 15 degrees or more, receives radio waves that are reflected by a moving object, and detects the presence or absence of the moving object within the detection range,
an antenna unit that transmits and receives a first polarized wave and a second polarized wave that are polarized differently from each other;
a polarization switching unit that switches between transmission and reception of the first polarized wave and transmission and reception of the second polarized wave;
a switching signal output unit that outputs a polarization switching signal that instructs the polarization switching unit to switch between the first polarized wave and the second polarized wave at a predetermined polarization switching cycle;
a high-frequency circuit that performs processing related to transmission/reception signals of the antenna unit;
connected to the high-frequency circuit;
Using a criterion set according to the environment in which the radio wave sensor is installed, a first Doppler signal based on the transmitted and received signal of the first polarization and a second Doppler signal based on the transmitted and received signal of the second polarization a determination unit that determines the presence or absence of the moving object in the detection range based on the detection result and a signal level difference that is the difference between the amplitude level of the first Doppler signal and the amplitude level of the second Doppler signal;
including
the polarization switching cycle is within a time width in which the same mobile object can transmit and receive the first polarized wave and the second polarized wave;
The determination unit
If the first Doppler signal and the second Doppler signal are not detected, determining that the moving object is not within the detection range;
When detecting the first Doppler signal and the second Doppler signal,
determining that the moving object is within the detection range when the signal level difference is less than the determination criterion;
If the signal level difference is equal to or greater than the determination criterion, determining that there is a moving object outside the detection range and that the moving object is not within the detection range;
radio sensor. 2. The radio wave sensor according to claim 1, wherein the polarization directions of the first polarized wave and the second polarized wave are orthogonal to each other. Installed on a first wall surface, facing the first wall surface, incident on the second wall surface with respect to a predetermined detection range that is a spatial region between the second wall surface of the radio wave transparent wall A radio wave detection method using a radio wave sensor that transmits radio waves with an angle of 15 degrees or more, receives radio waves that are reflected by a moving object, and detects the presence or absence of the moving object within the detection range,
transmitting a first polarized wave and a second polarized wave having different polarizations from each other by switching between the first polarized wave and the second polarized wave at a predetermined polarization switching cycle;
Using a criterion set according to the environment in which the radio wave sensor is installed, a first Doppler signal based on the transmitted and received signal of the first polarization and a second Doppler signal based on the transmitted and received signal of the second polarization Based on the detection result and the signal level difference, which is the difference between the amplitude level of the first Doppler signal and the amplitude level of the second Doppler signal,
If the first Doppler signal and the second Doppler signal are not detected, determining that the moving object is not within the detection range;
When detecting the first Doppler signal and the second Doppler signal,
determining that the moving object is within the detection range when the signal level difference is less than the determination criterion;
If the signal level difference is equal to or greater than the determination criterion, determining that there is a moving object outside the detection range and that the moving object is not within the detection range;
Radio wave detection method.

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