JP2018004508A - Radio wave sensor and detection program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio wave sensor and a detection program capable of detecting an object more accurately by using radio waves. A radio wave sensor is a transmitting unit that repeatedly transmits radio waves of a predetermined pattern, a receiving unit that receives radio waves, a frequency component of radio waves transmitted by the transmitting unit, and radio waves received by the receiving unit. A pattern signal acquisition unit that has a frequency component different from the frequency component and generates a difference signal for each pattern, and the difference signal of the corresponding timing in the plurality of patterns are added to the plurality of timings in the pattern. It includes an addition unit and a detection unit that detects an object based on the difference signals of the plurality of timings added by the addition unit. [Selection diagram] Fig. 3

Description

  The present invention relates to a radio wave sensor and a detection program.

  In recent years, radio wave sensors for detecting pedestrians on pedestrian crossings have been developed. For example, Patent Document 1 (Japanese Patent Laid-Open No. 2013-257210) discloses the following technique. That is, the pedestrian detector is installed above a sidewalk or a roadway, uses the boundary between the sidewalk and the roadway as a detection area, and irradiates the detection area with an electromagnetic wave of a predetermined frequency to detect the frequency of the reflected wave. Doppler radar, a calculation unit that determines the presence or absence of a pedestrian passing through the detection area from the sidewalk side toward the roadway side based on the frequency of the reflected wave detected by the Doppler radar, and determination by the calculation unit And an output means for outputting a pedestrian detection signal.

JP2013-257210A

Koji Yoichi, 2 others, “Application of expanding millimeter-wave technology”, [online], [Search May 22, 2016], Internet <URL: http: // www. spc. co. jp / spc / pdf / giho21_09. pdf> Takayuki Inaba, Tetsuro Kirimoto, “Automotive Millimeter Wave Radar”, Automotive Technology, February 2010, Vol. 64, No. 2, p. 74-79

  In the pedestrian detector described in Patent Document 1, it is possible to detect the presence or absence of a pedestrian passing through the boundary, which is a detection area, from the sidewalk side toward the roadway side. It is difficult to detect pedestrians in

  On the other hand, for example, a method of transmitting a radio wave to a target area including a pedestrian crossing and detecting a pedestrian on the crosswalk based on a radio wave received from the target area is conceivable.

  However, the reflectivity of pedestrian radio waves is generally small and fluctuates greatly. When such a pedestrian is located at a location away from the radio wave sensor, the intensity of the reflected radio wave from the pedestrian received by the radio wave sensor is weak and the intensity is not stable. For this reason, undetected in which the radio wave sensor cannot detect the pedestrian occurs despite the presence of the pedestrian.

  This invention was made in order to solve the above-mentioned subject, and the objective is to provide the electromagnetic wave sensor and detection program which can detect a target object correctly using an electromagnetic wave.

  (1) In order to solve the above-described problem, a radio wave sensor according to an aspect of the present invention is transmitted by a transmission unit that repeatedly transmits a predetermined pattern of radio waves, a reception unit that receives radio waves, and the transmission unit. A pattern signal acquisition unit that generates a differential signal for each pattern having a frequency component that is a difference between a frequency component of a radio wave and a frequency component of a radio wave received by the reception unit, and a plurality of timings in the pattern, An addition unit that adds the difference signals at the corresponding timings in the pattern, and a detection unit that detects an object based on the difference signals at the plurality of timings respectively added by the addition unit.

  (5) In order to solve the above-described problem, a detection program according to an aspect of the present invention is a detection program used in a radio wave sensor that repeatedly transmits and receives radio waves of a predetermined pattern. A pattern signal acquisition unit that generates a difference signal for each pattern having a frequency component that is a difference between a frequency component of a transmitted radio wave and a frequency component of a received radio wave, and a plurality of timings in the pattern Program for functioning as an addition unit that adds the difference signals at the corresponding timings, and a detection unit that detects the object based on the difference signals at the plurality of timings, which are respectively added by the addition units. It is.

  The present invention can be realized not only as a radio wave sensor including such a characteristic processing unit, but also as a method using such characteristic processing as a step, or as a system including a radio wave sensor. be able to. Further, it can be realized as a semiconductor integrated circuit that realizes part or all of the radio wave sensor.

  According to the present invention, an object can be detected more correctly using radio waves.

FIG. 1 is a diagram showing a configuration of a safe driving support system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an installation example at an intersection of the safe driving support system according to the embodiment of the present invention as viewed obliquely from above. FIG. 3 is a diagram showing a configuration of the radio wave sensor in the safe driving support system according to the embodiment of the present invention. FIG. 4 is a diagram illustrating an example of a detection period and each sequence set by the control unit in the radio wave sensor according to the embodiment of the present invention. FIG. 5 is a diagram illustrating an example of each waveform of the trigger signal and the clock signal generated by the control unit and the clock generation circuit in the radio wave sensor according to the embodiment of the present invention. FIG. 6 is a diagram illustrating an example of each waveform of the transmission wave and the difference signal generated by the transmission unit and the difference signal generation unit in the radio wave sensor according to the embodiment of the present invention. FIG. 7 is a diagram showing a configuration of a signal processing unit in the radio wave sensor according to the embodiment of the present invention. FIG. 8 is a diagram illustrating an example of a processing spectrum generated by the FMCW processing unit in the radio wave sensor according to the embodiment of the present invention. FIG. 9 is a flowchart that defines an example of an operation procedure when the radio wave sensor according to the embodiment of the present invention detects an object. FIG. 10 is a diagram illustrating an example of each waveform of the transmission wave and the difference signal generated by the transmission unit and the difference signal generation unit in the modification example of the radio wave sensor according to the embodiment of the present invention.

  First, the contents of the embodiment of the present invention will be listed and described.

  (1) A radio wave sensor according to an embodiment of the present invention includes a transmitter that repeatedly transmits radio waves of a predetermined pattern, a receiver that receives radio waves, a frequency component of radio waves transmitted by the transmitter, and the reception A pattern signal acquisition unit that generates a difference signal for each pattern having a frequency component that is different from a frequency component of a radio wave received by the unit, and a plurality of timings in the pattern, and the corresponding timings in the plurality of patterns An addition unit for adding the difference signals, and a detection unit for detecting an object based on the difference signals at the plurality of timings added by the addition unit.

  With such a configuration, the ratio of the signal component to the noise component in the differential signal, that is, the SN ratio can be improved. For example, even when the intensity of the radio wave reflected by the pedestrian is weak or fluctuates. The signal component based on the radio wave can be correctly acquired from the difference signal. Thereby, undetected generation | occurrence | production of a pedestrian can be suppressed. Therefore, it is possible to detect the object more correctly using radio waves.

  (2) Preferably, the radio wave sensor further includes a movement speed acquisition unit that acquires a movement speed of the object, and the addition unit is based on the movement speed acquired by the movement speed acquisition unit, The number of the plurality of patterns to be added is determined.

  The degree of temporal change in the shape of the difference signal changes according to the magnitude of the moving speed of the object. For example, by reducing the number of patterns to be added when the moving speed is high and increasing the number when the moving speed is low, the effect of improving the SN ratio is reduced in the difference signal after integration. Can be prevented.

  (3) Preferably, the pattern includes a first sub-pattern in which a frequency increases by a predetermined amount per unit time and a second sub-pattern in which a frequency decreases by the predetermined amount per unit time, The adding unit calculates a first integrated signal obtained by adding the difference signals of the corresponding timings in the plurality of first sub patterns for a plurality of timings in the first sub pattern, and the adding unit includes: For a plurality of timings in the second sub-pattern, a second integrated signal obtained by adding the difference signals of the corresponding timings in the plurality of second sub-patterns is calculated. The integrated signal and the second integrated signal are added at each corresponding timing.

  With such a configuration, for example, when the frequency of the transmission wave changes with time like a triangular wave, the difference signals can be appropriately integrated.

  (4) Preferably, the object is a stationary object.

  While the signal component based on the radio wave from the stationary object does not change even when the integration time is increased, the signal component and the noise component based on the radio wave from the moving object greatly change with time. For this reason, for example, when the number of patterns to be added is increased by increasing the integration time, the signal component based on the radio wave from the stopped object can be acquired more correctly from the difference signal. Thereby, acquisition of a favorable background spectrum and detection of a parked vehicle can be performed, for example.

  (5) A detection program according to an embodiment of the present invention is a detection program used in a radio wave sensor that repeatedly transmits a radio wave of a predetermined pattern and receives a radio wave. A pattern signal acquisition unit that generates a difference signal for each pattern having a frequency component that is different from the frequency component of the received radio wave, and the plurality of timings in the pattern, the differences in the timings corresponding to the patterns. It is a program for functioning as an addition unit that adds signals and a detection unit that detects an object based on the difference signals at the plurality of timings added by the addition unit.

  With such a configuration, the ratio of the signal component to the noise component in the differential signal, that is, the SN ratio can be improved. For example, even when the intensity of the radio wave reflected by the pedestrian is weak or fluctuates. The signal component based on the radio wave can be correctly acquired from the difference signal. Thereby, undetected generation | occurrence | production of a pedestrian can be suppressed. Therefore, it is possible to detect the object more correctly using radio waves.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated. Moreover, you may combine arbitrarily at least one part of embodiment described below.

[Configuration and basic operation]
FIG. 1 is a diagram showing a configuration of a safe driving support system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an installation example at an intersection of the safe driving support system according to the embodiment of the present invention as viewed obliquely from above.

  1 and 2, a safe driving support system 301 includes a radio wave sensor 101, a relay device 141, a signal control device 151, a wireless transmission device 152, an antenna 153, and a pedestrian signal lamp 161. Is provided. The signal control device 151 and the pedestrian signal lamp 161 in the safe driving support system 301 constitute a traffic signal, and are installed, for example, in the vicinity of the intersection CS1.

[About the intersection]
For example, as shown in FIG. 2, a pedestrian crossing PC1 is provided near the intersection CS1. Here, the road where the pedestrian crossing PC1 is provided is defined as the target road Rd1. The target road Rd1 forms an intersection CS1. Further, a road that intersects the target road Rd1 at the intersection CS1 is defined as an intersection road Rd2.

  That is, the intersection of the target road Rd1 and the intersection road Rd2 is the intersection CS1. In other words, the intersection CS1 overlaps the target road Rd1 and overlaps the intersection road Rd2. Note that more roads may intersect at the intersection CS1.

  The target road Rd1 includes an outflow road Rde on which an unillustrated automobile Tgt1 that flows out from the intersection CS1 travels, and an inflow road Rdi on which the automobile Tgt1 that flows into the intersection CS1 travels. A lane TrL is provided between the outflow road Rde and the inflow road Rdi.

  On the opposite end of the inflow road Rdi with respect to the outflow road Rde, a sidewalk Pv1 is provided so as to extend along the target road Rd1. The sidewalk Pv1 changes the extension direction from the direction along the target road Rd1 to the direction along the intersection road Rd2 by extending along the arc-shaped corner cut CCe in the vicinity of the intersection CS1.

  Further, a sidewalk Pv2 is provided at an end of the outflow road Rde opposite to the inflow road Rdi so as to extend along the target road Rd1. The sidewalk Pv2 changes the extension direction from the direction along the target road Rd1 to the direction along the intersection road Rd2 by extending along the arc-shaped corner cut CCi in the vicinity of the intersection CS1.

  The target area A1 is at least a part of the irradiation range of the radio wave transmitted from the radio wave sensor 101, and is an area including, for example, all of the pedestrian crossing PC1.

  The radio wave sensor 101 can detect an object in the target area A1. More specifically, the radio wave sensor 101 detects the pedestrian Tgt2 crossing the road using the pedestrian crossing PC1 as the target object Tgt in the target area A1. Here, the pedestrian Tgt2 is not limited to a person walking, but includes a bicycle and the like. In addition to the pedestrian Tgt2, the target object Tgt may include an automobile Tgt1 that travels along the target road Rd1 and passes through the pedestrian crossing PC1.

[Radio wave sensor installation position]
The radio wave sensor 101 is installed, for example, in the vicinity of the target road Rd1. Specifically, the radio wave sensor 101 is fixed to a support column PW installed on the side opposite to the target road Rd1 with respect to the sidewalk Pv1. More specifically, the radio wave sensor 101 is provided on an extension line of the pedestrian crossing PC1 toward the sidewalk Pv1.

  The relay device 141 is fixed to the column PW. Although not shown in FIG. 2, the radio wave sensor 101 and the relay device 141 are connected by a signal line, for example. The relay device 141 performs a relay process for transmitting information received from the radio wave sensor 101 to the signal control device 151.

  The signal control device 151 and the wireless transmission device 152 are fixed to a column PV installed on the sidewalk Pv2. The antenna 153 is fixed to the top of the support PV.

  The two pedestrian signal lamps 161 are fixed to the columns PW and PV, respectively. The signal control device 151, the wireless transmission device 152, the relay device 141, and the two pedestrian signal lamps 161 are respectively connected by signal lines, which are not shown in FIG. 2. Although not shown in FIG. 2, the wireless transmission device 152 and the antenna 153 are connected by a signal line.

  The radio wave sensor 101 transmits radio waves to the target area A1. Objects located in the target area A1, for example, the automobile Tgt1, the pedestrian Tgt2, the support PV, and the like reflect the radio wave transmitted from the radio wave sensor 101. The radio wave sensor 101 receives a radio wave reflected by an object.

  The radio wave sensor 101 detects the pedestrian Tgt2 in the pedestrian crossing PC1 based on the received radio wave, and transmits the detection result to the signal control device 151 via the relay device 141.

  Under the control of the signal control device 151, the pedestrian signal lamp 161 lights up and displays “recommend” or “to rare” for the pedestrian Tgt2 crossing the pedestrian crossing PC1.

  For example, the signal control device 151 extends the remaining time when the detection result indicates that the pedestrian Tgt2 is detected at the pedestrian crossing PC1 in the case where the remaining time for turning on “recommend” in the pedestrian signal lamp 161 is small. I do. Note that the signal control device 151 may notify the pedestrian Tgt2 by voice that there is little remaining time to light “Recommend”.

  In addition, the signal control device 151 walks that it is dangerous when the detection result indicates that the pedestrian Tgt2 is detected in the pedestrian crossing PC1 when “Tare rare” is turned on in the pedestrian signal lamp 161. Warn the person Tgt2 by voice.

  Further, the signal control device 151 provides a service to the automobile Tgt1 based on the detection result received from the radio wave sensor 101.

  Specifically, the signal control device 151 creates pedestrian warning information indicating that the pedestrian Tgt2 in the pedestrian crossing PC1 should be noted when the detection result indicates that the pedestrian Tgt2 exists in the pedestrian crossing PC1. The created pedestrian warning information is transmitted to the wireless transmission device 152.

  When the wireless transmission device 152 receives the pedestrian warning information from the signal control device 151, the wireless transmission device 152 generates a radio wave including the received pedestrian warning information, and transmits the generated radio wave via the antenna 153 so that the radio transmission device 152 is located around the intersection CS1. The pedestrian warning information is notified to the automobile Tgt1 to perform.

  For example, when the vehicle Tgt1 (not shown) that is going to turn right or left from the intersection road Rd2 and pass the pedestrian crossing PC1 receives a radio wave transmitted from the wireless transmission device 152, the vehicle Tgt1 acquires pedestrian warning information included in the received radio wave. Then, based on the acquired pedestrian warning information, the driver of the automobile Tgt1 is notified that attention should be paid to the crossing object in the pedestrian crossing PC1.

[Configuration of radio wave sensor]
FIG. 3 is a diagram showing a configuration of the radio wave sensor in the safe driving support system according to the embodiment of the present invention.

  With reference to FIG. 3, the radio wave sensor 101 includes a transmission unit 1, a reception unit 2, a differential signal generation unit 3, a control unit 4, a signal processing unit 5, a clock generation circuit 6, and a detection processing unit ( A detection unit and a movement speed acquisition unit) 7.

  The transmission unit 1 includes a transmission antenna 21, a power amplifier 22, a directional coupler 23, a VCO (Voltage-Controlled Oscillator) 24, a voltage generation unit 25, and a switch 26. The receiving unit 2 includes a receiving antenna 31 and a low noise amplifier 32.

  The differential signal generation unit 3 includes a mixer 33, an IF (Intermediate Frequency) amplifier 34, a low-pass filter 35, and an A / D converter (ADC) 36.

  The radio wave sensor 101 is, for example, Non-Patent Document 1 (Koji Yoichi, 2 others, “Application of expanding millimeter wave technology”, [online], [Search May 22, 2016], Internet <URL: http: //Www.spc.co.jp/spc/pdf/giho21_09.pdf> and Non-Patent Document 2 (Takayuki Inaba, Tetsuro Kirimoto, “Automotive Millimeter Wave Radar”, Automotive Technology, February 2010, 64th Vol. 2, No. 2, P. 74-79) is a radar that detects an object Tgt using the FM-CW method.

  FIG. 4 is a diagram illustrating an example of a detection period and each sequence set by the control unit in the radio wave sensor according to the embodiment of the present invention. In FIG. 4, the horizontal axis represents time.

  Referring to FIG. 4, control unit 4 in radio wave sensor 101 sets, for example, a detection period in which self radio wave sensor 101 outputs a detection result of target Tgt once.

  More specifically, the control unit 4 sets a detection period having a length Pm based on, for example, the moving speed of the object Tgt. The length Pm is variable, for example. Details of the method of setting the detection period length Pm will be described later.

  The detection period includes, for example, M sequences of Seq1 to SeqM. Here, M is an integer of 2 or more. In one sequence, one pattern of radio waves or one sub-pattern of radio waves is transmitted from the transmitter 1.

  FIG. 5 is a diagram illustrating an example of each waveform of the trigger signal and the clock signal generated by the control unit and the clock generation circuit in the radio wave sensor according to the embodiment of the present invention. In FIG. 5, the horizontal axis indicates time, and the vertical axis indicates the level of each signal.

  Referring to FIG. 5, clock generation circuit 6 generates a clock signal, for example. Specifically, the clock generation circuit 6 generates a rectangular wave clock signal CS having a period Tc, for example, as shown in FIG. The clock generation circuit 6 outputs the generated clock signal CS to the control unit 4 and the differential signal generation unit 3.

  The control unit 4 sets each sequence. More specifically, the control unit 4 generates a trigger signal TS for each start timing of each sequence, and outputs the generated trigger signal TS to the transmission unit 1 and the signal processing unit 5.

  Specifically, for example, the control unit 4 counts the number of rising edges of the clock signal CS received from the clock generation circuit 6, and generates and outputs the trigger signal TS every time Ns of the edges are counted. Here, Ns is an integer of 2 or more, and may be a predetermined value or variable. A value obtained by multiplying the period Tc by Ns is a period Tt of one sequence. In this example, the value of Ns is set so that the period Tt is, for example, 0.1 milliseconds to several milliseconds.

  FIG. 6 is a diagram illustrating an example of each waveform of the transmission wave and the difference signal generated by the transmission unit and the difference signal generation unit in the radio wave sensor according to the embodiment of the present invention. In FIG. 6, the horizontal axis indicates time, and the vertical axis indicates the frequency Ft and Fr of the transmission radio wave and the reception radio wave, the frequency Fb of the differential signal, and the amplitude Ab of the differential signal in order from the upper side of the page. The frequency Ft of the transmission radio wave is represented by a solid line, and the frequency Fr of the reception radio wave is represented by a broken line. In FIG. 6, the delay of the received radio wave with respect to the transmitted radio wave is shown.

  Referring to FIGS. 3 and 6, transmitting unit 1 repeatedly transmits a predetermined pattern of radio waves. Specifically, the transmission unit 1 repeatedly transmits, for example, a radio wave generated using an FM-CW modulation method to the target area A1. More specifically, for example, as illustrated in FIG. 6, the transmission unit 1 repeatedly transmits a radio wave having a pattern Pt1 whose frequency Ft increases by a predetermined amount per unit time to the target area A1.

  The transmission unit 1 may transmit a radio wave having a pattern in which the frequency Ft decreases by a predetermined amount per unit time. Further, the pattern of the radio wave transmitted by the transmission unit 1 is not limited to the configuration determined by the time change of the frequency as shown in FIG.

  The control unit 4 outputs transmission parameters used in the FM-CW method to the transmission unit 1, the signal processing unit 5, and the detection processing unit 7, for example, every detection period. Here, the transmission parameters include a sweep start frequency F2, a frequency sweep direction, a frequency sweep width Δf, a sequence period Tt, a sweep time Ts, and a detection period length Pm.

  Further, the control unit 4 generates a guard signal GS indicating the start timing of a guard period during which no radio wave is transmitted from the transmission unit 1 at the timing when the sweep time Ts has elapsed since the generation of the trigger signal TS, and outputs the guard signal GS to the transmission unit 1. To do.

  The guard signal GS is synchronized with the clock signal CS. The guard period is provided at the rear of each sequence, for example, and continues until the trigger signal TS indicating the start timing of the next sequence is output after the guard signal GS is output. Note that the guard period may be provided at the front of each sequence.

  When receiving the trigger signal TS from the control unit 4, the voltage generation unit 25 in the transmission unit 1 uses the sweep start frequency F2, the frequency sweep direction, the frequency sweep width Δf, and the sweep time Ts received from the control unit 4 in advance as transmission parameters. Until the guard signal GS is received from the control unit 4, a voltage whose magnitude increases at a constant rate (hereinafter also referred to as FM modulation voltage) is generated and output to the VCO 24.

  The VCO 24 generates a transmission wave RFt having a frequency corresponding to the magnitude of the voltage received from the voltage generator 25.

  More specifically, the VCO 24 generates a transmission wave RFt in the 24 GHz band having a frequency sweep width of Δf in accordance with the FM modulation voltage received from the voltage generation unit 25 and outputs it to the directional coupler 23.

  The directional coupler 23 distributes the transmission wave RFt received from the VCO 24 to the switch 26 and the differential signal generator 3.

  The switch 26 has a first end connected to the directional coupler 23 and a second end connected to the power amplifier 22. When the switch 26 receives the trigger signal TS from the control unit 4, the switch 26 transitions to the ON state and electrically connects the first end and the second end. On the other hand, when the switch 26 receives the guard signal GS from the control unit 4, the switch 26 transits to an off state and electrically insulates the first end and the second end. Thereby, the transmission wave RFt output from the VCO 24 is not transmitted to the power amplifier 22 in the guard period, and is transmitted to the power amplifier 22 in a period different from the guard period.

  The power amplifier 22 amplifies the transmission wave RFt received from the switch 26, and transmits the amplified transmission wave RFt to the target area A1 via the transmission antenna 21.

  The receiving unit 2 receives radio waves from the target area A1 and the like. More specifically, the receiving antenna 31 in the receiving unit 2 stops the target Tgt in the target area A1, specifically, movable objects such as the pedestrian Tgt2 and the automobile Tgt1, and the guardrail and the column PV. It is possible to receive radio waves reflected by an object. Below, operation | movement of the radio wave sensor 101 suitable when the target object Tgt is a movable object is demonstrated.

  In addition, the receiving antenna 31 may receive a radio wave transmitted by an interference object that transmits the interference radio wave. The interference object is, for example, an electronic scanning millimeter wave radar device mounted on the automobile Tgt1 located in the target area A1 or outside the target area A1.

  The low noise amplifier 32 amplifies the received wave RFr <b> 1 that is a radio wave received by the receiving antenna 31 and outputs the amplified signal to the differential signal generation unit 3.

  The difference signal generation unit 3 generates a difference signal having a frequency component that is the difference between the frequency component of the radio wave transmitted by the transmission unit 1 and the frequency component of the radio wave received by the reception unit 2.

  More specifically, the mixer 33 in the difference signal generation unit 3 generates an analog difference signal Ba1 having a frequency component of the difference between the transmission wave RFt received from the transmission unit 1 and the reception wave RFr1 received from the low noise amplifier 32.

  The time change of the frequency Fb and the amplitude Ab of the difference signal Ba1 is shown in FIG. The mixer 33 outputs the generated difference signal Ba1 to the IF amplifier 34.

  The IF amplifier 34 amplifies the difference signal Ba1 received from the mixer 33 and outputs it to the low-pass filter 35.

  The low-pass filter 35 attenuates a component having a frequency equal to or higher than a predetermined frequency among the frequency components of the difference signal Ba1 amplified by the IF amplifier 34.

  The A / D converter 36 performs the sampling process of the difference signal Ba1, for example, at the cycle Tc of the clock signal CS. More specifically, the A / D converter 36 uses the difference signal Ba1 that has passed through the low-pass filter 35 according to the timing of the rising edge of the clock signal CS received from the clock generation circuit 6 to q bits (q is 2 or more) for each sampling period Tc. To the digital differential signal Bd1.

  In FIG. 6, each sampling timing in the sequences Seq1 and Seq2 is indicated by white circles. Sampling numbers 1 to 12 indicating the sampling order are assigned to the sampling timing in each sequence. The A / D converter 36 outputs the converted difference signal Bd1 to the signal processing unit 5.

  FIG. 7 is a diagram showing a configuration of a signal processing unit in the radio wave sensor according to the embodiment of the present invention.

  Referring to FIG. 7, signal processing unit 5 includes a memory 41, an FFT (Fast Fourier Transform) processing unit 42, an FMCW processing unit 43, a pattern signal acquisition unit 44, and an addition unit 45.

  The memory 41 in the signal processing unit 5 accumulates the differential signal Bd1 received from the A / D converter 36.

  The pattern signal acquisition unit 44 generates a difference signal Bd1 (hereinafter also referred to as a pattern signal) for each pattern Pt1. More specifically, the pattern signal acquisition unit 44 recognizes the start timing and end timing of one sequence based on the trigger signal TS received from the control unit 4.

  Then, for example, every time a sequence ends, the pattern signal acquisition unit 44 takes out the time-series difference signal Bd1 sampled at the sampling period Tc in the sequence, that is, the pattern signal from the memory 41. The pattern signal acquisition unit 44 outputs the extracted pattern signal to the addition unit 45.

  The adding unit 45 adds difference signals of corresponding timings in the plurality of patterns Pt1 for the plurality of timings in the pattern Pt1. Specifically, the adding unit 45 adds difference signals having the same sampling number in the plurality of patterns Pt1 for each sampling timing indicated by the sampling numbers 1 to 12 in the pattern Pt1.

  More specifically, for example, the adding unit 45 determines the number M of a plurality of patterns to be added for each detection period.

  For example, the adding unit 45 determines the number M based on the detection period length Pm and the period Tt included in the transmission parameter received from the control unit 4.

  Specifically, the adding unit 45 determines the value M obtained by dividing the length Pm of the detection period by the period Tt.

  The adder 45 receives the pattern signal repeatedly from the pattern signal acquisition unit 44. Specifically, for example, when the addition unit 45 receives a pattern signal from the pattern signal acquisition unit 44 at the timing when the sequence Seq1 shown in FIG. 6 expires, the addition unit 45 accumulates the received pattern signal as a target pattern signal. The pattern signal includes the amplitude Ab sampled at each sampling timing indicated by the sampling numbers 1 to 12.

  And the addition part 45 will perform the following processes, if a pattern signal is received from the pattern signal acquisition part 44 in the timing which sequence Seq2 expires.

  That is, the adding unit 45 updates the target pattern signal by adding each amplitude Ab included in the target pattern signal and each amplitude Ab included in the pattern signal of the sequence Seq2 between the amplitudes Ab having the same sampling number.

  The adder 45 similarly updates the target pattern signal at the timing when the sequences Seq3 to SeqM expire. The adding unit 45 outputs the updated target pattern signal to the FFT processing unit 42.

  When receiving the target pattern signal from the adding unit 45, the FFT processing unit 42 performs the FFT process on the received target pattern signal to generate the power spectrum FS1 and the phase spectrum PS1. Here, the power spectrum FS1 indicates the amplitude of each frequency component included in the difference signal Bd1 accumulated in the detection period. The phase spectrum PS1 indicates the phase of each frequency component included in the difference signal Bd1 accumulated during the detection period.

  The FFT processing unit 42 outputs the generated power spectrum FS1 and phase spectrum PS1 to the FMCW processing unit 43.

  FIG. 8 is a diagram illustrating an example of a processing spectrum generated by the FMCW processing unit in the radio wave sensor according to the embodiment of the present invention. In FIG. 8, the vertical axis indicates the intensity, and the horizontal axis indicates the distance from the radio wave sensor 101 to the object.

  The FMCW processing unit 43 determines whether an object exists based on the radio wave received by the receiving unit 2.

  Specifically, the FMCW processing unit 43 holds a background spectrum that is a power spectrum in a state where no movable objects such as a pedestrian Tgt2 and a car Tgt1 exist in the target area A1, for example.

  When receiving the power spectrum FS1 and the phase spectrum PS1 from the FFT processing unit 42, the FMCW processing unit 43 generates a processing spectrum by subtracting each frequency component of the background spectrum from each frequency component of the received power spectrum FS1.

  Further, the FMCW processing unit 43 converts the frequency Fb of the generated processing spectrum and the frequency Fb of the phase spectrum PS1 into a distance L.

More specifically, the relationship between the frequency Fb and the distance L is expressed by the following formula (1) based on the formula (1) in Non-Patent Document 1.

  Here, c is the speed of light. vr is a moving speed of an object along a direction approaching or moving away from the radio wave sensor 101 (hereinafter also referred to as a detection target speed). f0 is an average of the sweep start frequency F2 and the sweep end frequency F1 obtained by adding the frequency sweep width Δf to the sweep start frequency F2.

For example, in the formula (1), when the frequency sweep width Δf is large with respect to the length of the period during which radio waves are transmitted in one sequence, that is, the sweep time Ts, the distance L is approximated as the following formula (2). Can be expressed.

  The FMCW processing unit 43 sets the frequency Fb on the horizontal axis of the processing spectrum and the phase spectrum PS1 to the distance L by using the frequency sweep width Δf and the sweep time Ts included in the transmission parameter received from the control unit 4 and Expression (2). Convert. FIG. 8 shows a processed spectrum in which the horizontal axis is converted from frequency to distance.

  The FMCW processing unit 43 performs peak detection processing on the generated processing spectrum. More specifically, the FMCW processing unit 43 analyzes the processing spectrum and tries to detect a peak having an intensity equal to or higher than a predetermined threshold value Thfm.

  The FMCW processing unit 43 determines that an object exists when a peak having an intensity equal to or greater than the threshold value Thfm can be detected. In this example, the FMCW processing unit 43 detects one peak Pn1 and determines that an object exists. On the other hand, the FMCW processing unit 43 determines that no object exists when a peak having an intensity equal to or greater than the threshold value Thfm cannot be detected.

  The FMCW processing unit 43 outputs to the detection processing unit 7 result information indicating the determination result, the detected intensity of the peak Pn1, and the distance L corresponding to the peak Pn1.

  Referring to FIG. 3 again, the detection processing unit 7 detects the object Tgt based on the difference signals at a plurality of timings added by the adding unit 45.

  Specifically, the detection processing unit 7 detects the object Tgt based on the result information received from the FMCW processing unit 43.

  More specifically, for example, when the determination result indicated by the result information indicates the absence of an object, the detection processing unit 7 determines that the target object Tgt does not exist.

  On the other hand, for example, when the determination result indicated by the result information indicates the presence of the object, the detection processing unit 7 selects the pedestrian Tgt2 or the automobile Tgt1 as the type of the target Tgt based on the magnitude of the peak intensity indicated by the result information. Identify. Specifically, when the peak intensity is large, the detection processing unit 7 determines the type of the object Tgt as the automobile Tgt1, and when the peak intensity is small, the detection processing unit 7 determines the type of the object as the pedestrian Tgt2.

  In addition, the detection processing unit 7 determines whether or not the object Tgt exists on the pedestrian crossing PC1 based on the distance L indicated by the result information.

  The detection processing unit 7 transmits a detection result indicating the presence / absence of the target Tgt and the type of the target Tgt in the pedestrian crossing PC1 to the relay device 141.

  Moreover, the detection process part 7 acquires the moving speed of the target object Tgt, for example. Specifically, the detection processing unit 7 calculates the detection target speed of the object Tgt as the moving speed based on the radio wave received by the receiving unit 2, for example.

  More specifically, the detection processing unit 7 records the correspondence between the detected identifier of the target Tgt and the distance from the radio wave sensor 101 to the target Tgt for each detection period, and detects the latest detection period. The distance to which the object Tgt has moved is divided by the length Pm of the detection period included in the transmission parameter received from the control unit 4 to obtain the detection target speed of the object Tgt. The detection processing unit 7 outputs speed information indicating the detection target speed of the acquired object Tgt, that is, the moving speed, to the control unit 4.

  For example, the control unit 4 sets the length Pm of the detection period based on the speed information received from the signal processing unit 5.

  More specifically, the control unit 4 sets the length Pm of the detection period based on the speed information and the sampling period Tc of the A / D converter 36, for example.

  For example, the processing spectrum shown in FIG. 8 is composed of discrete intensity data of frequency intervals based on the sampling period Tc, that is, distance intervals. For example, when the interval between the intensity data is X meters, the change of the distance L of the object Tgt in the detection period by X meters corresponds to the shift of the peak position in the processing spectrum by one point. Therefore, the change in the distance L of the object Tgt during the detection period is preferably smaller than the interval of intensity data in the processing spectrum.

  For example, the control unit 4 calculates a value obtained by dividing the interval by the moving speed indicated by the speed information, and sets a value obtained by multiplying the calculated value by a predetermined safety factor Rs as the length Pm of the detection period. Here, the safety factor Rs is a positive real number smaller than 1, for example.

  Specifically, the control unit 4 sets a smaller value as the length Pm of the detection period as the movement speed increases, and sets a larger value as the length Pm of the detection period as the movement speed decreases.

  The detection period length Pm is provided with a predetermined upper limit value and lower limit value. In this example, the predetermined upper limit is, for example, 100 milliseconds. The predetermined lower limit is, for example, one sequence period Tt.

  Referring to FIG. 7 again, the adding unit 45 determines the number of patterns to be added based on, for example, the moving speed acquired by the detection processing unit 7.

  More specifically, the adding unit 45 updates the number M based on the detection period length Pm and the period Tt included in the transmission parameter received from the control unit 4.

  The radio wave sensor 101 includes a computer, and an arithmetic processing unit such as a CPU in the computer reads and executes a program including a part or all of each step of the flowchart shown below from a memory (not shown). The program of this apparatus can be installed from the outside. The program of this device is distributed in a state stored in a recording medium.

[Operation]
FIG. 9 is a flowchart that defines an example of an operation procedure when the radio wave sensor according to the embodiment of the present invention detects an object.

  Referring to FIG. 9, first, radio wave sensor 101 sets a detection period having a default value, for example, a length Pm of 100 milliseconds (step S102).

  Next, the radio wave sensor 101 generates one pattern signal in each sequence until M sequences in the detection period expire (NO in step S104), and when generation of M pattern signals is completed (in step S104). YES), the target pattern signal is generated by adding the difference signal Bd1 of the same sampling number in the M patterns Pt1 (step S106).

  Next, the radio wave sensor 101 generates a power spectrum FS1 and a phase spectrum PS1 by performing FFT processing on the generated target pattern signal (step S108).

  Next, the radio wave sensor 101 generates a processing spectrum by subtracting each frequency component of the background spectrum from each frequency component of the power spectrum FS1, and performs a peak detection process on the generated processing spectrum (step S110).

  Next, when the radio wave sensor 101 detects a peak in the processing spectrum (YES in step S112), the radio wave sensor 101 calculates a distance L and a moving speed based on the detected peak (step S114).

  Next, the radio wave sensor 101 identifies the type and position of the object in the target area A1, that is, the target object Tgt (step S116).

  Next, the radio wave sensor 101 determines the length Pm of the detection period based on the moving speed of the object Tgt (step S118).

  Next, the radio wave sensor 101 determines the number M of the plurality of patterns Pt1 to be added based on the determined length Pm of the detection period (step S120).

  Next, the radio wave sensor 101 determines the number M (step S120) or sets a new detection period (step S122) when no peak is detected in the processing spectrum (NO in step S112).

  Next, the radio wave sensor 101 generates one pattern signal in each sequence until M sequences in the detection period expire (NO in step S104).

  When the radio wave sensor 101 detects a plurality of peaks in step S112, that is, when a plurality of objects are detected, the radio wave sensor 101 may execute steps S104 to S122 for each detected object.

[Variation 1 of the radio wave sensor 101]
Hereinafter, an operation of the radio wave sensor 101 suitable for a case where the target object Tgt is a stopped object will be described.

  In this modification, in the radio wave sensor 101, the length Pm of the detection period is set to a long time of about several seconds to several tens of hours and is fixedly operated.

  When the FFT processing unit 42 receives the target pattern signal, which is the pattern signal accumulated in the detection period, from the adding unit 45, the FFT processing unit 42 performs FFT processing on the received target pattern signal to thereby obtain the power spectrum FS1 and the phase spectrum PS1. Is generated.

  The power spectrum FS1 generated in this way is used as a background spectrum. That is, the noise included in the pattern signal and the signal component based on the radio wave from the movable object are smoothed in the integration over a long time. For this reason, the peak included in the power spectrum FS1 is a peak based on radio waves from a stationary object. Therefore, such a power spectrum FS1 is suitable for the background spectrum.

[Variation 2 of the radio wave sensor 101]
FIG. 10 is a diagram illustrating an example of each waveform of the transmission wave and the difference signal generated by the transmission unit and the difference signal generation unit in the modification example of the radio wave sensor according to the embodiment of the present invention. 10 is the same as FIG.

  In this modification, the time change of the frequency of the transmission wave is approximately a triangular wave. More specifically, the frequency pattern of the radio wave transmitted by the transmitter 1 includes, for example, a sub pattern SPt1 in which the frequency increases by a predetermined amount per unit time and a sub pattern SPt2 in which the frequency decreases by the predetermined amount per unit time. Is included. In this example, radio waves having the frequency of the sub-pattern SPt1 are transmitted in the odd-numbered sequence, and radio waves having the frequency of the sub-pattern SPt2 are transmitted in the even-numbered sequence.

  The pattern signal acquisition unit 44 generates, for example, a difference signal Bd1 for each of the sub patterns SPt1 and SPt2. More specifically, for example, every time a sequence ends, the pattern signal acquisition unit 44 extracts the difference signal Bd1 sampled in the sequence from the memory 41, and adds the extracted difference signal Bd1, that is, the sub-pattern signal, to the addition unit 45. Output to.

  For example, for the plurality of timings in the sub-pattern SPt1, the addition unit 45 calculates the integrated signal AS1 obtained by adding the difference signals Bd1 of the corresponding timings in the plurality of sub-patterns SPt1.

  Specifically, the adding unit 45 adds difference signals having the same sampling number in the plurality of sub patterns SPt1 for each sampling timing indicated by the sampling numbers 1 to 12 in the sub pattern SPt1.

  More specifically, for example, adder 45 accumulates the sub-pattern signal received from pattern signal acquisition unit 44 as integration signal AS1 at the timing when sequence Seq1 shown in FIG. 10 expires.

  When the adding unit 45 receives the sub pattern signal from the pattern signal acquisition unit 44 at the timing when the sequence Seq3 (not shown) expires, the adding unit 45 includes each amplitude Ab included in the integrated signal AS1 and each sub pattern signal included in the sequence Seq3. The accumulated signal AS1 is updated by adding the amplitude Ab to the amplitude Ab having the same sampling number.

  The adder 45 similarly updates the integration signal AS1 at the timing when each odd-numbered sequence expires until the M-th sequence SeqM expires.

  Further, the adding unit 45 calculates, for example, an integrated signal AS2 obtained by adding the difference signals Bd1 of corresponding timings in the plurality of sub patterns SPt2 for a plurality of timings in the sub pattern SPt2.

  Specifically, the adding unit 45 adds difference signals having the same sampling number in the plurality of sub patterns SPt2 for each sampling timing indicated by the sampling numbers 1 to 12 in the sub pattern SPt2.

  More specifically, for example, adder 45 accumulates the sub-pattern signal received from pattern signal acquisition unit 44 as integrated signal AS2 at the timing when sequence Seq2 shown in FIG. 10 expires.

  Then, when the addition unit 45 receives the sub pattern signal from the pattern signal acquisition unit 44 at the timing when the sequence Seq4 (not shown) expires, each addition unit 45 includes each amplitude Ab included in the integration signal AS2 and each subpattern signal included in the sequence Seq4. The accumulated signal AS2 is updated by adding the amplitude Ab to the amplitude Ab having the same sampling number.

  The adder 45 similarly updates the integration signal AS2 at the timing when each even-numbered sequence expires until the M-th sequence SeqM expires.

  For example, the adding unit 45 adds the integrated signal AS1 and the integrated signal AS2 at each corresponding timing.

  More specifically, the adding unit 45 adds a predetermined amount Q to one of the sampling numbers of the integration signals AS1 and AS2, for example.

  Here, the predetermined amount Q is, for example, a registered integer value. A method for calculating the predetermined amount Q will be described later.

  In this example, the adding unit 45 resets the sampling number to (1 + Q) to (12 + Q) by adding a predetermined amount Q to the sampling number of the integrated signal AS2, that is, 1 to 12, respectively. That is, the adding unit 45 moves the integration signal AS2 in the time axis direction according to the predetermined amount Q.

  Further, the adder 45 obtains sampling number data that cannot form a set of sampling numbers that coincide with each other in the sampling number of the integrated signal AS1, that is, 1 to 12, and the sampling number of the integrated signal AS2, that is, (1 + Q) to (12 + Q). delete.

  Specifically, for example, when the predetermined amount Q is 2, the adding unit 45 deletes the data of the sampling numbers 1 and 2 in the integration signal AS1 and the data of the sampling numbers 13 and 14 in the integration signal AS2. delete.

  The adder 45 assumes that the sampling timing of the data of sampling numbers 3 to 12 in the integrated signal AS1 corresponds to the sampling timing of the data of sampling numbers 3 to 12 after resetting in the integrated signal AS2, respectively. Process.

  That is, the adding unit 45 generates the target pattern signal by adding each amplitude Ab included in the integrated signal AS1 and each amplitude Ab included in the integrated signal AS2 between the amplitudes Ab having the same sampling number.

  Here, a method of calculating the predetermined amount Q will be described. The predetermined amount Q is, for example, the difference between the phase of the difference signal in the odd-numbered sequence and the phase of the difference signal in the even-numbered sequence.

  More specifically, for example, in a power spectrum and a phase spectrum obtained by performing FFT processing on a difference signal in an odd-numbered sequence, a phase Ph1 corresponding to a certain peak in the power spectrum is acquired from the phase spectrum. Further, in the power spectrum and the phase spectrum obtained by performing the FFT processing on the difference signal in the even-numbered sequence, the phase Ph2 corresponding to the peak is obtained from the phase spectrum.

  For example, the predetermined amount Q is calculated as an integer closest to a numerical value obtained by dividing the time difference corresponding to the difference between the phases Ph1 and Ph2 by the sampling period Tc.

  In the radio wave sensor according to the embodiment of the present invention, the FMCW processing unit 43 is configured to calculate the moving speed of the object Tgt based on the radio wave received by the receiving unit 2. It is not limited. The FMCW processing unit 43 may be configured to acquire the moving speed of the object Tgt from another sensor such as an image sensor.

  Moreover, in the radio wave sensor according to the embodiment of the present invention, the transmission unit 1 is configured to repeatedly transmit the radio wave of the FM-CW pattern, but is not limited thereto. The transmission unit 1 may be configured to repeatedly transmit radio waves of other modulation schemes such as a pulse scheme.

  By the way, in the pedestrian detector described in Patent Document 1, it is possible to detect the presence or absence of a pedestrian passing through the boundary, which is a detection region, from the sidewalk side toward the roadway side. It is difficult to detect pedestrians on pedestrian crossings.

  On the other hand, for example, a method of transmitting a radio wave to a target area including a pedestrian crossing and detecting a pedestrian on the crosswalk based on a radio wave received from the target area is conceivable.

  However, the reflectance of radio waves by pedestrians is generally small and varies greatly. When such a pedestrian is located at a location away from the radio wave sensor, the intensity of the reflected radio wave from the pedestrian received by the radio wave sensor is weak and the intensity is not stable. For this reason, undetected in which the radio wave sensor cannot detect the pedestrian occurs despite the presence of the pedestrian.

  On the other hand, in the radio wave sensor according to the embodiment of the present invention, the transmission unit 1 repeatedly transmits radio waves having a predetermined pattern. The receiving unit 2 receives radio waves. The pattern signal acquisition unit 44 generates a differential signal for each pattern having a frequency component that is a difference between the frequency component of the radio wave transmitted by the transmission unit 1 and the frequency component of the radio wave received by the reception unit 2. The adding unit 45 adds difference signals of corresponding timings in a plurality of patterns for a plurality of timings in the pattern. And the detection process part 7 detects the target object Tgt based on the difference signal of the some timing each added by the addition part 45. FIG.

  With such a configuration, the ratio of the signal component to the noise component in the differential signal, that is, the SN ratio can be improved. For example, when the intensity of the radio wave reflected by the pedestrian Tgt2 is weak and fluctuates. In addition, the signal component based on the radio wave can be correctly acquired from the difference signal. Thereby, undetected generation | occurrence | production of pedestrian Tgt2 can be suppressed. Therefore, it is possible to detect the object more correctly using radio waves.

  Further, in the radio wave sensor according to the embodiment of the present invention, the detection processing unit 7 acquires the moving speed of the object Tgt. Then, the adding unit 45 determines the number of patterns to be added based on the moving speed acquired by the detection processing unit 7.

  The degree of temporal change in the shape of the difference signal changes according to the magnitude of the moving speed of the object Tgt. For example, by reducing the number of patterns to be added when the moving speed is high and increasing the number when the moving speed is low, the effect of improving the SN ratio is reduced in the difference signal after integration. Can be prevented.

  In the radio wave sensor according to the embodiment of the present invention, the pattern includes a sub-pattern SPt1 whose frequency increases by a predetermined amount per unit time and a sub-pattern SPt2 whose frequency decreases by the predetermined amount per unit time. It is. The adding unit 45 calculates an integrated signal AS1 obtained by adding difference signals of corresponding timings in the plurality of sub patterns SPt1 for a plurality of timings in the sub pattern SPt1. The adding unit 45 calculates an integrated signal AS2 obtained by adding difference signals of corresponding timings in the plurality of sub patterns SPt2 for a plurality of timings in the sub pattern SPt2. Then, the adding unit 45 adds the integration signal AS1 and the integration signal AS2 for each corresponding timing.

  With such a configuration, for example, when the frequency of the transmission wave changes with time like a triangular wave, the difference signals can be appropriately integrated.

  In the radio wave sensor according to the embodiment of the present invention, the target object Tgt is a stationary object.

  While the signal component based on the radio wave from the stationary object does not change even if the integration time is increased, the signal component and the noise component based on the radio wave from the moving object change greatly with time. For this reason, for example, when the number of patterns to be added is increased by increasing the integration time, the signal component based on the radio wave from the stopped object can be acquired more correctly from the difference signal. Thereby, acquisition of a favorable background spectrum and detection of a parked vehicle can be performed, for example.

  The above embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The above description includes the following features.

[Appendix 1]
A transmitter that repeatedly transmits radio waves of a predetermined pattern;
A receiver for receiving radio waves;
A pattern signal acquisition unit that generates a differential signal for each of the patterns, having a frequency component that is a difference between a frequency component of a radio wave transmitted by the transmission unit and a frequency component of a radio wave received by the reception unit;
For a plurality of timings in the pattern, an adding unit that adds the difference signals of the corresponding timings in the plurality of patterns;
A detection unit for detecting an object based on the difference signals at the plurality of timings, which are respectively added by the addition unit,
The object is a human, a bicycle or a car,
The transmission unit repeatedly transmits radio waves of the pattern of FM-CW method or pulse method,
The pattern signal acquisition unit generates the digital difference signal for each pattern,
The radio wave sensor, wherein the adding unit uses the sampling number indicating the sampling order of the digital difference signal to add the difference signals at the corresponding timings in the plurality of patterns for the plurality of timings in the pattern.

DESCRIPTION OF SYMBOLS 1 Transmission part 2 Reception part 3 Differential signal generation part 4 Control part 5 Signal processing part 6 Clock generation circuit 7 Detection processing part (detection part and moving speed acquisition part)
21 Transmitting antenna 22 Power amplifier 23 Directional coupler 24 VCO
25 Voltage Generator 26 Switch 31 Receiving Antenna 32 Low Noise Amplifier 33 Mixer 34 IF Amplifier 35 Low Pass Filter 36 A / D Converter (ADC)
Reference Signs List 41 Memory 42 FFT processing unit 43 FMCW processing unit 44 Pattern signal acquisition unit 45 Addition unit 101 Radio wave sensor 141 Relay device 151 Signal control device 152 Wireless transmission device 153 Antenna 161 Pedestrian signal lamp 301 Safe driving support system

Claims (5)

A transmitter that repeatedly transmits radio waves of a predetermined pattern;
A receiver for receiving radio waves;
A pattern signal acquisition unit that generates a differential signal for each of the patterns, having a frequency component that is a difference between a frequency component of a radio wave transmitted by the transmission unit and a frequency component of a radio wave received by the reception unit;
For a plurality of timings in the pattern, an adding unit that adds the difference signals of the corresponding timings in the plurality of patterns;
A radio wave sensor comprising: a detection unit that detects an object based on the difference signals at the plurality of timings, which are respectively added by the addition unit. The radio wave sensor further includes:
A moving speed acquisition unit for acquiring the moving speed of the object;
The radio wave sensor according to claim 1, wherein the adding unit determines the number of the plurality of patterns to be added based on the moving speed acquired by the moving speed acquiring unit. The pattern includes a first sub-pattern whose frequency increases by a predetermined amount per unit time and a second sub-pattern whose frequency decreases by the predetermined amount per unit time,
The adding unit calculates a first integrated signal obtained by adding the difference signals of the corresponding timings in the plurality of first sub patterns for a plurality of timings in the first sub pattern,
The adding unit calculates a second integrated signal obtained by adding the difference signals of the corresponding timings in the plurality of second sub patterns for a plurality of timings in the second sub pattern,
The radio wave sensor according to claim 1, wherein the adding unit adds the first integrated signal and the second integrated signal at corresponding timings.   The radio wave sensor according to claim 1, wherein the object is a stationary object. A detection program used in a radio wave sensor that repeatedly transmits and receives radio waves of a predetermined pattern,
Computer
A pattern signal acquisition unit that generates a difference signal for each of the patterns having a frequency component that is a difference between the frequency component of the transmitted radio wave and the frequency component of the received radio wave;
For a plurality of timings in the pattern, an adding unit that adds the difference signals of the corresponding timings in the plurality of patterns;
A detection unit for detecting an object based on the difference signals of the plurality of timings, which are respectively added by the addition unit;
Detection program to function as

Images