JP2017036944A - Radio wave sensor - Google Patents

Abstract

An object is correctly detected while suppressing power consumption.
A radio wave sensor includes a signal generation unit that generates a modulation signal, a DA conversion unit that converts the modulation signal generated by the signal generation unit into an analog signal, and the analog signal that is converted by the DA conversion unit. A transmission unit that converts a signal into a radio wave and transmits it to a target area, a reception unit that receives a radio wave from the target area and generates a reception signal, and converts the reception signal generated by the reception unit into a digital signal An AD converter, a detector that detects an object in the target area based on the digital signal converted by the AD converter, a DA sampling frequency that is a sampling frequency in the DA converter, and the AD At least one of AD sampling frequencies, which are sampling frequencies in the conversion unit, is sent to the detection unit And a control unit for changing in response to that detection result.
[Selection] Figure 2

Description

  The present invention relates to a radio wave sensor, and more particularly, to a radio wave sensor that detects an object using a modulation signal.

  A pulse compression radar that uses pulse compression, which is a technology that uses a transmission signal with a wide pulse width that has undergone special modulation within the pulse as a transmission pulse, performs demodulation in the processing after reception and converts it to a narrow pulse width, Non-Patent Document 1 (edited and published by the Institute of Electronics, Information and Communication Engineers, supervised by Takashi Yoshida, “Revised Radar Technology”, revised edition, Corona, October 1996, P275-280).

Edited and published by the Institute of Electronics, Information and Communication Engineers Supervised by Takashi Yoshida, “Revised Radar Technology”, revised edition, Corona, October 1996, P275-280 Koji Yoichi, two others, “Application of expanding millimeter-wave technology”, [online], [searched July 8, 2015], Internet <URL: http: // www. spc. co. jp / spc / pdf / giho21_09. pdf>

  When measuring the target distance from the pulse compression radar to the target object in the target area using the pulse compression radar described in Non-Patent Document 1, the maximum detection distance and the distance resolution are the time width of the transmission pulse and the transmission pulse. Determined by the bandwidth of each.

  For example, when improving the distance resolution while maintaining the maximum detection distance, it is conceivable to perform measurement using a transmission pulse having a wide bandwidth. In this case, since the bandwidth of the transmission pulse and the bandwidth of the reflected pulse generated by reflecting the transmission pulse on the object are both wide, high-speed signal processing is required in the pulse compression radar.

  When performing high-speed signal processing in a pulse compression radar, for example, an AD (analog-digital) converter and a DA (digital-analog) converter that can operate at high speed are required. However, when the AD converter and the DA converter are operated at high speed, there is a problem that power consumption increases.

  This invention was made in order to solve the above-mentioned subject, The objective is to provide the electromagnetic wave sensor which can detect a target object correctly, suppressing power consumption.

  (1) In order to solve the above problems, a radio wave sensor according to an aspect of the present invention includes a signal generation unit that generates a modulation signal, and a DA that converts the modulation signal generated by the signal generation unit into an analog signal. A conversion unit; a transmission unit that converts the analog signal converted by the DA conversion unit into a radio wave and transmits the radio signal to a target area; a reception unit that receives a radio wave from the target area and generates a reception signal; An AD converter that converts the received signal generated by the receiver into a digital signal; a detector that detects an object in the target area based on the digital signal converted by the AD converter; and the DA DA sampling frequency, which is a sampling frequency in the conversion unit, and AD sampling, which is a sampling frequency in the AD conversion unit At least one of wave numbers, and a control unit for changing according to the detection result by the detection unit.

  The present invention can be realized not only as a radio wave sensor including such a characteristic processing unit, but also as a system including a radio wave sensor, or as a method using such characteristic processing as a step, Such steps can be realized as a program for causing a computer to execute the steps. 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, it is possible to correctly detect an object while suppressing power consumption.

FIG. 1 is a diagram showing a configuration of a radar system according to an embodiment of the present invention. FIG. 2 is a diagram showing a configuration of the radio wave sensor in the radar system according to the embodiment of the present invention. FIG. 3 is a diagram illustrating an example of a waveform of the modulation signal generated by the signal generation unit in the radio wave sensor according to the embodiment of the present invention. FIG. 4 is a diagram showing the configuration of the DA converter in the radio wave sensor according to the embodiment of the present invention. FIG. 5 is a diagram showing a configuration of a transmission unit in the radio wave sensor according to the embodiment of the present invention. FIG. 6 is a diagram illustrating a configuration of a receiving unit in the radio wave sensor according to the embodiment of the present invention. FIG. 7 is a diagram showing an example of the arrangement of transmission antennas, reception antennas, and objects according to the embodiment of the present invention. FIG. 8 is a diagram showing a configuration of an AD conversion unit in the radio wave sensor according to the embodiment of the present invention. FIG. 9 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. 10 is a flowchart defining an operation procedure when the control unit in the radio wave sensor according to the embodiment of the present invention changes the sampling frequency. FIG. 11 is a flowchart defining an operation procedure when the control unit in the radio wave sensor according to the embodiment of the present invention changes the sampling frequency. FIG. 12 is a diagram showing an example of the relationship between the sampling frequency and the target distance changed by the control unit in 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 signal generation unit that generates a modulation signal, a DA conversion unit that converts the modulation signal generated by the signal generation unit into an analog signal, and the DA conversion. A transmission unit that converts the analog signal converted by the unit into a radio wave and transmits it to a target area, a reception unit that receives a radio wave from the target area and generates a reception signal, and the reception unit that generates the reception signal An AD converter that converts a received signal into a digital signal, a detector that detects an object in the target area based on the digital signal converted by the AD converter, and a sampling frequency in the DA converter At least one of a DA sampling frequency and an AD sampling frequency that is a sampling frequency in the AD converter And a control unit for changing according to the detection result by the detection unit.

  With such a configuration, it is possible to reduce at least one of the DA sampling frequency and the AD sampling frequency to such an extent that the detection result by the detection unit is not adversely affected, so that power consumption for sampling can be suppressed. . Therefore, it is possible to correctly detect the object while suppressing power consumption.

  (2) Preferably, the said control part changes at least the said AD sampling frequency among the said DA sampling frequency and the said AD sampling frequency according to the detection result by the said detection part.

  As described above, the power consumption can be more effectively suppressed by the configuration in which at least the AD sampling frequency, which has a larger power consumption suppressing effect than that in the case where the DA sampling frequency is changed, is changed according to the detection result by the detection unit. be able to.

  (3) Preferably, the said control part changes the said sampling frequency according to whether the said target object was detected by the said detection part.

  With such a configuration, it is possible to set an appropriate sampling frequency according to whether or not an object is detected.

  (4) More preferably, the control unit has a value larger than the sampling frequency when the object is detected by the detection unit compared to the sampling frequency when the object is not detected by the detection unit. Set to.

  With such a configuration, when the object is not detected by the detection unit, it is necessary to improve the detection accuracy, for example, by detecting the object by the detection unit while reducing the sampling frequency and suppressing power consumption. In this case, the sampling frequency can be increased.

  (5) Preferably, the detection unit detects a target distance that is a distance from the radio wave sensor to the target object in the target area based on the digital signal converted by the AD conversion unit, and the control The unit changes the sampling frequency according to the target distance detected by the detection unit.

  With such a configuration, an appropriate sampling frequency can be set according to the distance to the object.

  (6) More preferably, the control unit sets the sampling frequency when the target distance is equal to or smaller than a threshold to a value larger than the sampling frequency when the target distance is larger than the threshold. Set.

  With such a configuration, when an object is detected at a position away from the radio wave sensor, for example, the object is detected at a position closer to the radio wave sensor while reducing the power consumption while reducing the sampling frequency. The sampling frequency can be increased when it is necessary to ensure distance resolution.

  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 radar system according to an embodiment of the present invention. With reference to FIG. 1, a radar system 301 includes a radio wave sensor 101 and a control device 151.

  In FIG. 1, one radio wave sensor 101 is representatively shown, but a plurality of radio wave sensors 101 may be provided. Hereinafter, each of the objects Tgt1 and Tgt2 is also referred to as an object Tgt.

  The radio wave sensor 101 detects the object Tgt in the target area A1. The object Tgt is a human, for example. The target object Tgt is not limited to a human being, but may be any object or animal that can reflect radio waves.

  More specifically, the radio wave sensor 101 operates according to the control of the control device 151, for example. For example, with respect to the target Tgt in the target area A1, the radio wave sensor 101 detects the presence / absence of the target Tgt, the target distance Lt, and the detection target speed vd and notifies the control device 151 of the detection result. Details of the target distance Lt and the detection target speed vd will be described later.

[Characteristics of pulse radar]
For example, in a pulse radar for detecting an object Tgt using a pulsed radio wave, the maximum detection distance Lmax, which is the maximum distance at which the object Tgt can be detected, is a pulse-shaped signal transmitted from the pulse radar. It is determined by the average power of radio waves (hereinafter also referred to as transmission pulses). Therefore, in order to increase the maximum detection distance Lmax, it is required to increase the average power of the radio wave transmitted from the pulse radar.

  The average power of the transmission pulse is obtained, for example, by the product of the peak power, the transmission pulse width, and the repetition period. Therefore, for example, the maximum detection distance Lmax can be increased by increasing the transmission pulse width.

  Further, a pulsed radio wave (hereinafter also referred to as a reflected pulse) received by the pulse radar from the target area A1 is a pulsed radio wave (hereinafter also referred to as a target reflected pulse) reflected by the object Tgt in the target area A1. .) Is included.

  The pulse radar can measure the target distance, which is the distance between itself and the target Tgt, from the time difference from when the transmission pulse is transmitted to the target area A1 until the target reflection pulse is received.

  For example, as shown in FIG. 1, when two target objects Tgt1 and Tgt2 exist in the target area A1, the pulse radar transmits a transmission pulse Tw to the target area A1, and then reflects the target reflection from the target objects Tgt1 and Tgt2, respectively. Pulses Trw1 and Trw2 are received. For example, when at least a part of the target reflected pulses Trw1 and Trw2 received by the pulse radar overlap, the pulse radar determines both the target distance Lt1 between itself and the target Tgt1 and the target distance Lt2 between the self and the target Tgt2. It becomes difficult to measure correctly.

  Here, among the cases where the pulse radar can correctly measure both the target distances Lt1 and Lt2, the absolute value of the difference when the absolute value of the difference between the target distances Lt1 and Lt2 is minimized is defined as the distance resolution. To do.

  When the transmission pulse width is Tp, the distance resolution is about c × Tp / 2. Here, c is the speed of light. Therefore, in order to improve the distance resolution, it is required to reduce the transmission pulse width Tp.

  However, when the transmission pulse width Tp is reduced, the maximum detection distance Lmax is reduced as described above. As a radar that solves such a trade-off relationship between the distance resolution and the maximum detection distance Lmax, for example, there is a pulse compression radar shown in Non-Patent Document 1. In the pulse compression radar, a modulation pulse including a modulation signal that is a modulated signal is used as a transmission pulse.

  The distance resolution of the pulse compression radar is determined, for example, by the bandwidth of the modulation signal included in the modulation pulse. Further, the maximum detection distance Lmax of the pulse compression radar is determined by the transmission pulse width Tp of the modulation pulse. Therefore, in the pulse compression radar, the distance resolution and the maximum detection distance Lmax can be independently changed.

[Configuration of radio wave sensor]
FIG. 2 is a diagram showing a configuration of the radio wave sensor in the radar system according to the embodiment of the present invention.

  Referring to FIG. 2, the radio wave sensor 101 includes a transmission unit 21, a DA conversion unit 22, a signal generation unit 23, a control unit 24, an AD conversion unit 25, a signal processing unit 26, and a clock generation circuit 27T. 27R, a receiving unit 28, and oscillators 29 and 30. Hereinafter, each of the clock generation circuits 27T and 27R is also referred to as a clock generation circuit 27.

  The radio wave sensor 101 is, for example, a pulse compression radar. For example, when installing the radio wave sensor 101, the user of the radio wave sensor 101 sets the maximum detection distance Lmax and the distance resolution necessary for the radar performance. Then, the user determines the transmission pulse width Tp and the modulation signal bandwidth that can satisfy the set maximum detection distance Lmax and distance resolution, respectively.

  The user adopts, for example, the waveform shown in FIG. 11.8 (c) on page 278 of Non-Patent Document 1 as the waveform of the modulated signal having the determined transmission pulse width Tp and the bandwidth of the modulated signal.

[Modulation signal]
FIG. 3 is a diagram illustrating an example of a waveform of the modulation signal generated by the signal generation unit in the radio wave sensor according to the embodiment of the present invention. In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates amplitude.

  Referring to FIG. 3, modulated signal MS has, for example, a waveform shown in FIG. 11.8 (c) on page 278 of Non-Patent Document 1, more specifically a waveform based on a code sequence according to a Barker code of N = 7. .

  Here, for example, a period during which the modulation signal MS oscillates between an amplitude of +1 and an amplitude of −1, that is, a period from timing t0 to t7 is a transmission period in which radio waves are to be transmitted from the transmission unit 21. For example, a modulation pulse, that is, a transmission pulse Tw is transmitted from the radio wave sensor 101 during the transmission period. The length of the transmission period corresponds to the pulse width Tp of the modulation signal MS, that is, the transmission pulse width Tp of the transmission pulse Tw.

  Timings from timing t0 to Tp / 7 are timings t1 to t7, respectively. The amplitude of the modulation signal MS is zero until timing t0 and after timing t7. The amplitude of the modulation signal MS is +1 from timing t0 to timing t3, -1 from timing t3 to timing t5, +1 from timing t5 to timing t6, and from timing t6 to timing t7. Until -1.

  Referring to FIG. 2 again, clock generation circuit 27 generates, for example, a clock signal. More specifically, the clock generation circuit 27 can change the frequency of the clock signal, for example.

  For example, the control unit 24 changes the DA sampling frequency that is the sampling frequency in the DA conversion unit 22 and the AD sampling frequency that is the sampling frequency in the AD conversion unit 25.

  Specifically, the control unit 24 changes the pulse width and DA sampling frequency of the modulation signal MS by controlling the clock generation circuit 27T, for example. More specifically, the control unit 24 performs control to change the frequency of a clock signal (hereinafter also referred to as a transmission-side clock signal) generated in the clock generation circuit 27T, for example, thereby changing the pulse of the modulation signal MS. Change the width and DA sampling frequency.

  More specifically, for example, the control unit 24 outputs a transmission side setting signal STH, STM, or STL having a level for setting the frequency of the transmission side clock signal to fTH, fTM, or fTL to the clock generation circuit 27T.

  Here, the frequency fTH is set so that, for example, the modulation signal MS shown in FIG. 3 can be generated. Specifically, the frequency fTH is, for example, the reciprocal of Tp / 7. Further, the frequencies fTM and fTL are set so that the relationship fTH> fTM> fTL is satisfied. Specific values of the frequencies fTH, fTM, and fTL are, for example, 1 GHz, 500 MHz, and 250 MHz, respectively.

  For example, the clock generation circuit 27T generates a transmission side clock signal having a frequency corresponding to the level of the transmission side setting signal received from the control unit 24, and sends the generated transmission side clock signal to the DA conversion unit 22 and the signal generation unit 23. Output.

  For example, when receiving the transmission side setting signal STH, STM or STL from the control unit 24, the clock generation circuit 27T generates a transmission side clock signal having a frequency fTH, fTM or fTL according to the level of each received signal. The generated transmission side clock signal is output to the DA converter 22 and the signal generator 23.

  The control unit 24 changes the AD sampling frequency by controlling the clock generation circuit 27R, for example. Specifically, the control unit 24 changes the AD sampling frequency by performing control to change the frequency of a clock signal (hereinafter also referred to as a reception-side clock signal) generated in the clock generation circuit 27R, for example. .

  More specifically, for example, the control unit 24 outputs a reception side setting signal SRH, SRM, or SRL having a level for setting the frequency of the reception side clock signal to fRH, fRM, or fRL to the clock generation circuit 27R.

  Here, the frequencies fRH, fRM, and fRL are set to the same values as the frequencies fTH, fTM, and fTL, for example.

  The clock generation circuit 27R generates, for example, a reception-side clock signal having a frequency corresponding to the level of the reception-side setting signal received from the control unit 24, and the generated reception-side clock signal is sent to the AD conversion unit 25 and the signal processing unit 26. Output.

  For example, when receiving the reception side setting signal SRH, SRM or SRL from the control unit 24, the clock generation circuit 27R generates a reception side clock signal having the frequency fRH, fRM or fRL according to the level of each received signal. The generated reception side clock signal is output to the AD conversion unit 25 and the signal processing unit 26.

  Further, the control unit 24 creates, for example, amplitude data that is data for generating the modulation signal MS shown in FIG. The amplitude data includes, for example, seven numerical values “+1, +1, +1, −1, −1, +1, −1” in order from the top.

  The control unit 24 changes the pulse width of the modulation signal MS by directly controlling the signal generation unit 23, for example. Thereby, the control unit 24 can perform control to increase the pulse width of the modulation signal MS without changing the frequency of the transmission-side clock signal.

  More specifically, the control unit 24 sets a speed reduction magnification that is a magnification for increasing the pulse width of the modulation signal MS in the signal generation unit 23, for example. Here, the speed reduction magnification is an integer of 1 or more, for example.

  For example, the control unit 24 generates signal generation information including the generated amplitude data and the set speed reduction magnification, and outputs the generated signal generation information to the signal generation unit 23.

  Further, the control unit 24 creates setting information including, for example, amplitude data, the frequency of the transmission side clock signal, the speed reduction rate, and the frequency of the reception side clock signal, and outputs the created setting information to the signal processing unit 26.

  For example, when the control unit 24 receives a measurement start command from the control device 151, the control unit 24 creates a control signal for performing transmission / reception processing of the transmission pulse Tw and the reflected pulse by the own radio wave sensor 101 at a timing for each predetermined period. The generated control signal is output to the signal generation unit 23 and the signal processing unit 26.

  FIG. 4 is a diagram showing the configuration of the DA converter in the radio wave sensor according to the embodiment of the present invention. Referring to FIG. 4, DA converter 22 includes DA converters (DACs) 41I and 41Q.

  Referring to FIGS. 2 and 4, signal generation unit 23 generates modulated signal MS. More specifically, the signal generator 23 generates, for example, a pulsed modulation signal MS. Further, the signal generation unit 23 can change the bandwidth of the modulation signal MS.

  More specifically, for example, when the signal generation unit 23 receives the signal generation information from the control unit 24, the signal generation unit 23 acquires the speed reduction magnification and the amplitude data from the received signal generation information. Then, for example, the signal generation unit 23 multiplies the interval between the timings of the rising edge or the falling edge of the transmission side clock signal received from the clock generation circuit 27T (hereinafter also referred to as the transmission side clock timing) by the speed reduction factor. Set the interval as the numerical value acquisition interval.

  For example, when the speed reduction magnification is 1, the numerical value acquisition interval is equal to the transmission-side clock timing interval. For example, when the speed reduction magnification is 2, the numerical value acquisition interval is equal to twice the interval of the transmission side clock timing.

  For example, when receiving a control signal from the control unit 24, the signal generation unit 23 acquires each numerical value included in the amplitude data in order from the top at the set numerical value acquisition interval, and at the transmission side clock timing, A digital signal (hereinafter also referred to as a digital signal ITDS) and a digital signal for a Q component (hereinafter also referred to as a digital signal QTDS) are generated, and the generated digital signals ITDS and QTDS are converted into a DA converter 41I in the DA converter 22 and 41Q is output to each.

  More specifically, the signal generator 23 recognizes the timing of the numerical value acquisition interval using, for example, the transmission side clock timing. Further, for example, the signal generation unit 23 sequentially acquires each numerical value included in the amplitude data from the top at the recognized timing. In addition, the signal generation unit 23 generates a digital signal ITDS indicating the acquired numerical value at each transmission side clock timing, for example, and outputs the digital signal ITDS to the DA converter 41I.

  For example, when the frequency of the transmission side clock signal is changed by the control unit 24, the numerical value acquisition interval changes. Further, when the speed reduction magnification is changed by the control unit 24, the numerical value acquisition interval changes. As a result, the pulse width Tp of the modulation signal MS generated by the signal generation unit 23 changes, so that the bandwidth of the modulation signal MS is changed.

  When the output of the digital signal ITDS indicating each numerical value in the amplitude data to the DA converter 41 is completed, the signal generation unit 23 performs the following processing until a new control signal is received from the control unit 24. That is, the signal generation unit 23 generates, for example, a digital signal ITDS indicating zero at each transmission side clock timing, and outputs the generated digital signal ITDS to the DA converter 41I.

  Further, the signal generator 23 generates a digital signal QTDS indicating, for example, zero at each transmission side clock timing, and outputs the generated digital signal QTDS to the DA converter 41Q.

  FIG. 5 is a diagram showing a configuration of a transmission unit in the radio wave sensor according to the embodiment of the present invention. Referring to FIG. 5, transmission unit 21 includes low-pass filters 42I and 42Q, mixers 43I and 43Q, phase shifter 44, synthesizer 45, mixer 46, power amplifier 47, and transmission antenna 48. Including.

  Referring to FIGS. 4 and 5, DA converter 22 converts modulated signal MS generated by signal generator 23 into an analog signal.

  More specifically, the DA converters 41I and 41Q in the DA converter 22 operate according to the timing of the transmission side clock signal received from the clock generation circuit 27T, that is, the transmission side clock timing, for example.

  More specifically, the sampling period in the DA converters 41I and 41Q, that is, the reciprocal of the DA sampling frequency, corresponds to the interval of each transmission side clock timing. That is, when the interval between the transmission side clock timings changes, the DA sampling frequency in the DA converters 41I and 41Q changes. Thereby, the control unit 24 changes the DA sampling frequency in the DA converters 41I and 41Q.

  DA converters 41I and 41Q convert digital signals ITDS and QTDS received from signal generation unit 23 into analog signals ITAS and QTAS, respectively, at the DA sampling frequency.

  Specifically, when the numerical value indicated by the digital signal ITDS received from the signal generator 23 at each transmission side clock timing is +1 or −1, the DA converter 41I, for example, the analog signal ITAS having the maximum voltage Vmax or the minimum voltage Vmin. Is generated.

  Further, when the numerical value indicated by the digital signal ITDS received from the signal generation unit 23 is zero at each transmission side clock timing, the DA converter 41I generates, for example, an analog signal ITAS having an intermediate voltage between the maximum voltage Vmax and the minimum voltage Vmin. .

  The DA converter 41I outputs the generated analog signal ITAS to the low-pass filter 42I in the transmission unit 21.

  When the numerical value indicated by the digital signal QTDS received from the signal generation unit 23 is zero at each transmission side clock timing, the DA converter 41Q generates and generates an analog signal QTAS having an intermediate voltage between the maximum voltage Vmax and the minimum voltage Vmin, for example. The analog signal QTAS is output to the low-pass filter 42Q in the transmission unit 21.

  Referring to FIG. 2 again, oscillator 29 generates local signal Lo1 having a frequency of 1800 MHz and a sine wave, for example, and outputs the generated local signal Lo1 to transmitting unit 21 and receiving unit 28.

  For example, the oscillator 30 generates a local signal Lo2 having a frequency of 77 GHz and a sine wave waveform, and outputs the generated local signal Lo2 to the transmitter 21 and the receiver 28.

  Referring to FIG. 5 again, the transmission unit 21 converts the analog signal ITAS or QTAS converted by the DA conversion unit 22 into a radio wave and transmits it to the target area A1.

  More specifically, the low-pass filter 42I in the transmission unit 21 attenuates a component having a frequency equal to or higher than a predetermined frequency among the frequency components of the analog signal ITAS received from the DA converter 41I in the DA conversion unit 22.

  The low-pass filter 42Q attenuates a component having a frequency equal to or higher than a predetermined frequency among the frequency components of the analog signal QTAS received from the DA converter 41Q in the DA converter 22.

  For example, the phase shifter 44 shifts the phase of the local signal Lo1 received from the oscillator 29 by π / 2 and outputs the phase-shifted local signal Lo1 to the mixer 43Q.

  For example, the mixer 43I multiplies the analog signal ITAS that has passed through the low-pass filter 42I and the local signal Lo1 received from the oscillator 29, thereby converting the baseband analog signal ITAS into an analog signal ITAS in the 1800 MHz band. Then, the mixer 43I outputs the converted 1800 MHz band analog signal ITAS to the synthesizer 45. Here, for example, when the analog signal ITAS does not change with time during the period other than the transmission period, the mixer 43I does not output a signal to the synthesizer 45.

  For example, the mixer 43Q multiplies the analog signal QTAS that has passed through the low-pass filter 42Q and the local signal Lo1 that is received from the phase shifter 44 and that is out of phase by π / 2. Here, since analog signal QTAS does not change with time as an intermediate voltage, mixer 43Q does not output a signal to synthesizer 45.

  The combiner 45 combines the analog signal received from the mixer 43I and the analog signal received from the mixer 43Q, and outputs the combined analog signal to the mixer 46.

  Here, since the synthesizer 45 does not receive a signal from the mixer 43Q, for example, the synthesizer 45 outputs the 1800 MHz band analog signal ITAS received from the mixer 43I to the mixer 46.

  For example, the mixer 46 multiplies the analog signal ITAS in the 1800 MHz band received from the synthesizer 45 by the local signal Lo2 received from the oscillator 30 to convert the analog signal ITAS in the 1800 MHz band into the 78.8 GHz band that is the transmission pulse Tw. Is converted into an analog signal ITAS, that is, radio waves. Then, the mixer 46 outputs the converted radio wave to the power amplifier 47.

  The power amplifier 47 amplifies the radio wave received from the mixer 46 and transmits the amplified radio wave to the target area A 1 via the transmission antenna 48.

  FIG. 6 is a diagram illustrating a configuration of a receiving unit in the radio wave sensor according to the embodiment of the present invention. Referring to FIG. 6, receiving unit 28 includes mixers 63I and 63Q, a phase shifter 64, a mixer 66, a low noise amplifier 67, and a receiving antenna 68.

[Detection target speed]
FIG. 7 is a diagram showing an example of the arrangement of transmission antennas, reception antennas, and objects according to the embodiment of the present invention.

  Referring to FIG. 7, reception antenna 68 receives, for example, a radio wave from target area A1, that is, reflected pulse Rw. More specifically, the reflection pulse Rw received by the reception antenna 68 includes, for example, a target reflection pulse generated when the target Tgt moving in the target area A1 reflects the transmission pulse Tw transmitted by the transmission antenna 48. Trw is included.

  Here, the moving speed of the object Tgt along the direction approaching or moving away from the radio wave sensor 101 is defined as a detection target speed vd. In other words, the component of the relative speed of the target Tgt with respect to the receiving antenna 68 along the direction approaching or moving away from the radio wave sensor 101 is the detection target speed vd.

  For example, if the speed of the target Tgt relative to the receiving antenna 68 is defined as a relative speed vt, the detection target speed vd is represented by the inner product of the unit vector nd in the direction from the target Tgt to the receiving antenna 68 and the relative speed vt. .

  The frequency of the target reflection pulse Trw is shifted according to the detection target speed vd of the target Tgt with respect to the frequency of the transmission pulse Tw. More specifically, Non-Patent Document 2 (Koji Yoichi, 2 others, “Application of expanding millimeter-wave technology”, [online], [searched July 8, 2015], Internet <URL: http: /// According to the formula (11.a) on page 44 of www.spc.co.jp/spc/pdf/giho21_09.pdf>, for example, when the frequency of the transmission pulse Tw is f1, the frequency of the target reflected pulse Trw Is shifted by 2 × f1 × vd / c with respect to f1. The amplitude of the target reflection pulse Trw is an amplitude corresponding to the reflection cross-sectional area σ of the target Tgt.

  Referring to FIG. 6 again, receiving unit 28 receives radio waves from target area A1 and generates a received signal. More specifically, the low noise amplifier 67 in the receiving unit 28 amplifies the 78.8 GHz band analog signal RAS that is the reflected pulse Rw received by the receiving antenna 68, and the amplified 78.8 GHz band analog signal RAS in the mixer 66. Output to.

  For example, the mixer 66 multiplies the analog signal RAS in the 78.8 GHz band received from the low noise amplifier 67 by the local signal Lo2 received from the oscillator 30 to thereby multiply the analog signal RAS in the 78.8 GHz band into the analog signal RAS in the 1800 MHz band. Convert to Mixer 46 then outputs the converted 1800 MHz band analog signal RAS to mixers 63I and 63Q.

  For example, the mixer 63I multiplies the 1800 MHz band analog signal RAS received from the mixer 66 by the local signal Lo1 received from the oscillator 29 to convert the 1800 MHz band analog signal RAS into a baseband signal. An analog signal of I component, that is, a reception signal IRAS is generated. Then, the mixer 63I outputs the generated reception signal IRAS to the AD conversion unit 25.

  For example, the phase shifter 64 shifts the phase of the local signal Lo1 received from the oscillator 29 by π / 2, and outputs the phase-shifted local signal Lo1 to the mixer 63Q.

  The mixer 63Q, for example, multiplies the analog signal RAS in the 1800 MHz band received from the mixer 66 by the local signal Lo1 that is received from the phase shifter 64 and has a phase shifted by π / 2, and thereby based on the analog signal RAS in the 1800 MHz band. By converting to a band-band signal, an analog signal of Q component, that is, a reception signal QRAS is generated. Then, the mixer 63Q outputs the generated reception signal QRAS to the AD conversion unit 25.

  FIG. 8 is a diagram showing a configuration of an AD conversion unit in the radio wave sensor according to the embodiment of the present invention. Referring to FIG. 8, AD conversion unit 25 includes AD converters (ADC) 61I and 61Q.

  The AD conversion unit 25 converts the reception signals IRAS and QRAS generated by the reception unit 28 into digital signals.

  More specifically, AD converters 61I and 61Q in AD converter 25 follow, for example, the timing of the rising edge or falling edge of the receiving clock signal received from clock generation circuit 27R (hereinafter also referred to as receiving clock timing). Operate.

  More specifically, the sampling period in the AD converters 61I and 61Q, that is, the reciprocal of the AD sampling frequency, corresponds to the interval between the respective reception side clock timings. That is, when the interval between the respective receiving clock timings changes, the AD sampling frequency in the AD converters 61I and 61Q changes. Thereby, the control unit 24 changes the AD sampling frequency in the AD converters 61I and 61Q.

  AD converters 61I and 61Q convert reception signals IRAS and QRAS received from mixer 63I and mixer 63Q in reception unit 28 into digital signals IRDS and QRDS, respectively, at an AD sampling frequency.

  The AD converters 61I and 61Q output the converted digital signals IRDS and QRDS to the signal processing unit 26.

  FIG. 9 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. 9, signal processing unit 26 includes a pulse compression processing unit 81, an FFT (Fast Fourier Transform) processing unit 82, a detection unit 83, a buffer unit 84, and an aggregation unit 85.

  The buffer unit 84 in the signal processing unit 26 stores, for example, the digital signals IRDS and QRDS received from the AD conversion unit 25 at each timing of the reception-side clock signal received from the clock generation circuit 27R.

[Detection processing]
The detection unit 83 detects the object Tgt in the target area A1 based on the digital signal converted by the DA conversion unit 22.

[Target distance]
The pulse compression processing unit 81 in the detection unit 83 detects a target distance Lt, which is a distance from the radio wave sensor 101 to the target object Tgt in the target area A1, based on the digital signal converted by the AD conversion unit 25, for example.

  Specifically, the pulse compression processing unit 81 performs compression by performing pulse compression processing using the modulated signal MS generated by the signal generation unit 23 and the digital signals IRDS and QRDS converted by the AD conversion unit 25, for example. A pulse is generated, and the target distance Lt is detected based on the generated compressed pulse.

  More specifically, the pulse compression processing unit 81 acquires, for example, the amplitude data, the frequency of the transmission side clock signal and the speed reduction rate from the setting information received from the control unit 24, and the acquired amplitude data, the frequency of the transmission side clock signal Based on the speed reduction magnification, a detection function x (t) representing the modulation signal MS shown in FIG. 3 is created.

  The pulse compression processing unit 81 starts the origin of time t, which is a variable of the detection function x (t), for example, the timing at which the control signal is received from the control unit 24, that is, the radio wave sensor 101 starts transmission / reception processing of the transmission pulse Tw and the reflection pulse Set the timing.

  Further, the pulse compression processing unit 81 creates a reception function r (t) based on the digital signals IRDS and QRDS stored in the buffer unit 84, for example.

  More specifically, for example, the pulse compression processing unit 81 acquires the frequency of the reception side clock signal from the setting information, and calculates the sampling interval in the AD conversion unit 25 from the acquired frequency of the reception side clock signal.

  For example, the pulse compression processing unit 81 calculates the sampling timing of each digital signal IRDS and QRDS stored in the buffer unit 84 based on the calculated sampling interval and the timing at which the control signal is received.

  The pulse compression processing unit 81 acquires, for example, the digital signals IRDS and QRDS whose sampling timings are sm to sn from the buffer unit 84, and from the acquired digital signals IRDS and QRDS, the vector Riq [sm] to Riq [sn] is created.

  Here, the sampling timing sm is a timing before the pulse compression processing unit 81 receives a control signal from the control unit 24. The sampling timing sn is a timing after the reception signal based on the reflected pulse Rw is accumulated in the buffer unit 84. Further, the vector Riq [sk] has, for example, an I component and a Q component. More specifically, the I component and the Q component of the vector Riq [sk] are a value indicated by the digital signal IRDS and a value indicated by the digital signal QRDS, respectively, whose sampling timing is sk.

  For example, the pulse compression processing unit 81 performs a rotation process of rotating the vectors Riq [sm] to Riq [sn] by the same angle in the IQ plane so that the I component becomes large, and the vector Riq [sm after the rotation process is performed. ] To Riq [sn] are created as reception functions r (t).

  For example, the pulse compression processing unit 81 may include a compressed pulse by performing a convolution operation on the detection function x (t) and the reception function r (t) according to, for example, Equation (11.4) on page 277 of Non-Patent Document 1. A pulse compression process for calculating the function f (t) is performed.

  For example, when the function f (t) includes a compression pulse based on the target reflected pulse Trw from the target Tgt, the pulse compression processing unit 81 (c / 2) at the time corresponding to the peak position of the compression pulse. A value obtained by multiplying is detected as the target distance Lt.

  In addition, the pulse compression processing unit 81 may, for example, include 2 compression pulses based on the target reflection pulses Trw1 and Trw2 from the two objects Tgt1 and Tgt2 in the function f (t). A value obtained by multiplying the time corresponding to the position of each peak of each compression pulse by (c / 2) is calculated as the target distances Lt1 and Lt2.

  For example, the pulse compression processing unit 81 outputs the calculated target distances Lt1 and Lt2 and the corresponding compressed pulse peak intensities Ip1 and Ip2 to the aggregation unit 85.

[Detection target velocity vd and reflection intensity]
For example, the FFT processing unit 82 calculates the detection target speed vd of the target Tgt and the reflection intensity of the target Tgt based on the digital signal converted by the AD conversion unit 25.

  More specifically, the FFT processing unit 82 acquires, for example, the frequency of the reception side clock signal from the setting information, and calculates the sampling interval in the AD conversion unit 25 from the acquired frequency of the reception side clock signal.

  The FFT processing unit 82 calculates the sampling timing of each digital signal IRDS and QRDS stored in the buffer unit 84 based on, for example, the calculated sampling interval and the timing at which the control signal is received.

  The FFT processing unit 82 sets a time range for performing the FFT processing. The time range is, for example, a time corresponding to c / (2 × f1 × vdmin) when vdmin is set as the lower limit of the detection target speed.

  The FFT processing unit 82 acquires, for example, each digital signal IRDS for the set time range from the buffer unit 84, and performs FFT processing using the acquired digital signals IRDS as data of the time spectrum ITS, thereby obtaining the Doppler spectrum IDS. create. Here, the horizontal axis and the vertical axis in the Doppler spectrum are frequency and amplitude, respectively.

  For example, the FFT processing unit 82 identifies a peak in the Doppler spectrum IDS, and substitutes the identified peak frequency fbeat1 and the frequency f1 of the transmission pulse Tw into the equation (11.a) on page 44 of Non-Patent Document 2. The magnitude of the detection target speed vd of the target Tgt is calculated.

  Also, the FFT processing unit 82 calculates the reflection intensity Ir from the amplitude of the frequency fbeat1 in the Doppler spectrum IDS, for example.

  For example, when two peaks are specified in the Doppler spectrum IDS, the FFT processing unit 82 calculates the detection target velocities vd1 and vd2 and the reflection intensities Ir1 and Ir2 for each specified peak.

  The FFT processing unit 82 outputs, for example, the calculated detection target velocities vd1 and vd2 and the reflection intensities Ir1 and Ir2 to the aggregation unit 85 in the detection unit 83.

  The aggregating unit 85 aggregates the signal processing results in its own signal processing unit 26, for example. Specifically, the aggregation unit 85, for example, the detection target velocities vd1, vd2 and reflection intensities Ir1, Ir2 received from the FFT processing unit 82, and the target distances Lt1, Lt2 and peak intensities Ip1, Ip2 received from the pulse compression processing unit 81, for example. Aggregate.

  More specifically, for example, when at least one of the reflection intensities Ir1 and Ir2 is equal to or higher than the threshold value Thi, the aggregation unit 85 determines that the target object Tgt exists in the target area A1.

  Here, for example, since both of the reflection intensities Ir1 and Ir2 are equal to or higher than the threshold value Thi, the consolidating unit 85 determines that the objects Tgt1 and Tgt2 exist in the target area A1.

  In addition, the aggregation unit 85 specifies, for example, which of the target distances Lt1 and Lt2 is the target distance corresponding to the detection target speed vd1 and the reflection intensity Ir1.

  For example, the aggregating unit 85 specifies the target distance corresponding to the detection target velocity vd1 and the reflection intensity Ir1 based on the intensity ratio of the reflection intensities Ir1 and Ir2 and the intensity ratio of the peak intensities Ip1 and Ip2.

  Specifically, for example, when Ir1 / Ir2> 1 and Ip1 / Ip2 <1, the aggregating unit 85 specifies the target distance corresponding to the detection target speed vd1 and the reflection intensity Ir1 as Lt2, and When Ir1 / Ir2> 1 and Ip1 / Ip2> 1, the target distance corresponding to the detection target speed vd1 and the reflection intensity Ir1 is specified as Lt1.

  Here, for example, the aggregation unit 85 specifies the target distance corresponding to the detection target speed vd1 and the reflection intensity Ir1 as Lt1, and specifies the target distance corresponding to the detection target speed vd2 and the reflection intensity Ir2 as Lt2.

  For example, when the aggregation unit 85 determines that the target object Tgt exists in the target area A1, the aggregation unit 85 indicates that the target object Tgt has been detected, and includes detection result information including the target distance and the detection target speed for the target object Tgt. The data is output to the control unit 24 and transmitted to the control device 151.

  For example, when the detection unit 83 does not determine that the target object Tgt exists in the target area A1, the detection unit 83 outputs detection result information indicating that the target object Tgt has not been detected to the control unit 24 and the control device 151. Send to.

  The control unit 24 changes the DA sampling frequency that is the sampling frequency in the DA conversion unit 22 and the AD sampling frequency that is the sampling frequency in the AD conversion unit 25 according to the detection result by the detection unit 83.

  In addition, the control unit 24 changes the bandwidth of the modulation signal MS generated in the signal generation unit 23, for example, according to the changed AD sampling frequency.

  More specifically, when performing control to change the AD sampling frequency to a higher frequency, for example, the control unit 24 widens the bandwidth of the modulation signal MS by reducing the pulse width of the modulation signal MS.

  On the other hand, for example, when performing control to change the AD sampling frequency to a lower frequency, the control unit 24 narrows the bandwidth of the modulation signal MS by increasing the pulse width of the modulation signal MS.

  Specifically, for example, when the frequency of the reception side clock signal is set to fRH, fRM, or fRL, the control unit 24 sets the frequency of the transmission side clock signal to fTH, fTM, or fTL, respectively.

[Sampling frequency change 1]
For example, the control unit 24 changes the DA sampling frequency and the AD sampling frequency depending on whether or not the object Tgt is detected by the detection unit 83.

  Specifically, for example, when receiving detection result information indicating that the object Tgt has been detected from the detection unit 83, the control unit 24 changes the DA sampling and AD sampling frequencies.

  On the other hand, for example, when the control unit 24 receives detection result information indicating that the target Tgt has not been detected from the detection unit 83, the control unit 24 maintains the DA sampling and AD sampling frequencies.

  For example, the control unit 24 compares the DA sampling frequency and the AD sampling frequency when the target Tgt is detected by the detection unit 83 with the DA sampling frequency and the AD sampling frequency when the target Tgt is not detected by the detection unit 83. Set each to a larger value.

  Specifically, for example, when the radio wave sensor 101 is activated, the control unit 24 generates signal generation information including 1 as amplitude data and a speed reduction magnification, and outputs the generated signal generation information to the signal generation unit 23. To do.

  For example, the control unit 24 sets the operation mode of its own radio wave sensor 101 to either the high resolution mode or the low resolution mode.

  Specifically, the control unit 24 sets the operation mode to the high resolution mode when the radio wave sensor 101 is activated.

  When setting the high-resolution mode, the control unit 24 sets the DA sampling frequency to fTH by outputting the transmission-side setting signal STH to the clock generation circuit 27T and setting the frequency of the transmission-side clock signal to fTH.

  Further, when setting the high resolution mode, the control unit 24 sets the AD sampling frequency to fRH by outputting the reception side setting signal SRH to the clock generation circuit 27R and setting the frequency of the reception side clock signal to fRH. To do.

  For example, when receiving detection result information indicating that the object Tgt has not been detected from the detection unit 83, the control unit 24 sets the low resolution mode.

  When setting the low resolution mode, the control unit 24 outputs the transmission side setting signal STL to the clock generation circuit 27T and sets the frequency of the transmission side clock signal to fTL, thereby setting the DA sampling frequency to fTL smaller than fTH. Set.

  Further, when setting the low resolution mode, the control unit 24 outputs the reception side setting signal SRL to the clock generation circuit 27R and sets the frequency of the reception side clock signal to fRL, so that the AD sampling frequency is smaller than fRH. Set to fRL.

  For example, when the detection unit 83 receives detection result information indicating that the object Tgt has been detected from the detection unit 83, the control unit 24 sets the high resolution mode again.

[Operation]
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.

  FIG. 10 is a flowchart defining an operation procedure when the control unit in the radio wave sensor according to the embodiment of the present invention changes the sampling frequency.

  Referring to FIG. 10, control unit 24 sets the operation mode to the high resolution mode, for example, when radio wave sensor 101 is activated (step S102).

  Next, the control unit 24 starts repetitive transmission of the transmission pulse Tw to the target area A1 with respect to its own radio wave sensor 101, for example, by outputting a control signal to the signal generation unit 23 at a timing of a predetermined cycle. (Step S104).

  Next, the control unit 24 waits until detection result information is received from the signal processing unit 26 (NO in step S106).

  On the other hand, when receiving the detection result information from the signal processing unit 26 (YES in step S106), the control unit 24 performs the following processing.

  That is, the control unit 24 indicates that the received detection result information indicates that the object Tgt has not been detected, and the operation mode is the high resolution mode (NO in step S108 and YES in step S114). Is set to the low resolution mode (step S116).

  Next, the control unit 24 waits until the next detection result information is received from the signal processing unit 26 (NO in step S106).

  On the other hand, the control unit 24 indicates that the received detection result information indicates that the object Tgt has not been detected and the operation mode is the low resolution mode (NO in step S108 and NO in step S114). Without waiting for the next detection result information from the signal processing unit 26 (NO in step S106).

  Further, when the received detection result information indicates that the object Tgt has been detected and the operation mode is the low resolution mode (YES in step S108 and YES in step S110), the control unit 24 increases the operation mode. The resolution mode is set (step S112).

  Next, the control unit 24 waits until the next detection result information is received from the signal processing unit 26 (NO in step S106).

  On the other hand, the control unit 24 changes the operation mode when the received detection result information indicates that the object Tgt has been detected and the operation mode is the high resolution mode (YES in step S108 and NO in step S110). Without waiting until the next detection result information is received from the signal processing unit 26 (NO in step S106).

[Sampling frequency change 2]
For example, the control unit 24 changes the DA sampling frequency and the AD sampling frequency according to the target distance Lt detected by the detection unit 83.

  Specifically, for example, the control unit 24 sets the operation mode of its own radio wave sensor 101 to one of a high resolution mode, a medium resolution mode, and a low resolution mode.

  More specifically, the control unit 24 sets the operation mode to the high resolution mode when the radio wave sensor 101 is activated, for example.

  For example, the control unit 24 compares the DA sampling frequency and the AD sampling frequency when the target distance Lt is equal to or less than the threshold Th1 with the DA sampling frequency and the AD sampling frequency when the target distance Lt is larger than the threshold Th1. Set each to a larger value.

  Specifically, for example, when the control unit 24 receives detection result information from the detection unit 83 that indicates that the target object Tgt has been detected and includes the target distance Lt that is larger than the threshold Th1, the control unit 24 sets the operation mode to the low resolution. Set to mode.

  At this time, the control unit 24 outputs the transmission side setting signal STL and the reception side setting signal SRL to the clock generation circuits 27T and 27R, respectively.

  For example, the control unit 24 indicates that the target Tgt has been detected, and the detection unit 83 detects detection result information including the target distance Lt that is equal to or less than the threshold Th1 and that is greater than the threshold Th2. When receiving from, set the operation mode to medium resolution mode. Here, Th1> Th2. Specific values of the threshold values Th1 and Th2 are, for example, 100 m and 30 m, respectively.

  When setting the medium resolution mode, the control unit 24 sets the DA sampling frequency to fTM by outputting the transmission side setting signal STM to the clock generation circuit 27T and setting the frequency of the transmission side clock signal to fTM.

  Further, when setting the medium resolution mode, the control unit 24 sets the AD sampling frequency to fRM by outputting the reception side setting signal SRM to the clock generation circuit 27R and setting the frequency of the reception side clock signal to fRM. To do.

  For example, the control unit 24 compares the DA sampling frequency and the AD sampling frequency when the target distance Lt is equal to or less than the threshold Th2 with the DA sampling frequency and the AD sampling frequency when the target distance Lt is larger than the threshold Th2. Set each to a larger value.

  Specifically, for example, when the control unit 24 indicates that the target Tgt has been detected and receives detection result information including the target distance Lt equal to or less than the threshold value Th2, from the detection unit 83, the control unit 24 selects the operation mode with high resolution. Set to mode.

  At this time, the control unit 24 outputs the transmission side setting signal STH and the reception side setting signal SRH to the clock generation circuits 27T and 27R, respectively.

  For example, when receiving detection result information indicating that the object Tgt has not been detected from the detection unit 83, the control unit 24 sets the low resolution mode.

[Operation]
FIG. 11 is a flowchart defining an operation procedure when the control unit in the radio wave sensor according to the embodiment of the present invention changes the sampling frequency.

  Referring to FIG. 11, the operations in steps S202 to S204 are the same as the operations in steps S102 to S104 shown in FIG.

  Next, the control unit 24 waits until receiving detection result information from the signal processing unit 26 (NO in step S206).

  On the other hand, when receiving the detection result information from the signal processing unit 26 (YES in step S206), the control unit 24 performs the following processing.

  That is, the control unit 24 indicates that the received detection result information indicates that the object Tgt has not been detected and the operation mode is the high resolution mode or the medium resolution mode (NO in step S208 and YES in step S214). ), The operation mode is set to the low resolution mode (step S216).

  Next, the control unit 24 waits until the next detection result information is received from the signal processing unit 26 (NO in step S206).

  On the other hand, when the received detection result information indicates that the object Tgt has not been detected and the operation mode is the low resolution mode (NO in step S208 and NO in step S214), the control unit 24 operates. Without waiting for the next detection result information from the signal processing unit 26 (NO in step S206).

  Further, the control unit 24 indicates that the received detection result information indicates that the object Tgt has been detected and includes the object distance Lt that is larger than the threshold Th1 (YES in step S208 and YES in step S210). The mode is set to the low resolution mode (step S216).

  Further, the control unit 24 indicates that the received detection result information indicates that the target object Tgt has been detected, and includes the target distance Lt that is equal to or smaller than the threshold value Th1 and greater than the threshold value Th2 ( YES in step S208, NO in step S210 and YES in step S212), the operation mode is set to the medium resolution mode (step S218).

  Further, the control unit 24 indicates that the received detection result information indicates that the object Tgt is detected and includes the target distance Lt equal to or less than the threshold value Th2 (YES in step S208, NO in step S210, and step S212). NO), the operation mode is set to the high resolution mode (step S220).

  Next, when the control unit 24 sets the operation mode to the low resolution mode (step S216), sets to the medium resolution mode (step S218), or sets to the high resolution mode (step S220), the signal processing is performed. Wait until the next detection result information is received from the unit 26 (NO in step S206).

[Sampling frequency change 3]
FIG. 12 is a diagram showing an example of the relationship between the sampling frequency and the target distance changed by the control unit in the radio wave sensor according to the embodiment of the present invention. In FIG. 12, the vertical axis indicates the DA sampling frequency and the AD sampling frequency, and the horizontal axis indicates the target distance Lt. For example, the threshold values Th1 and Th2 are 100 m and 30 m, respectively.

  Referring to FIG. 12, for example, the control unit 24 changes the DA sampling frequency and the AD sampling frequency to values corresponding to the target distance Lt detected by the detection unit 83.

  Specifically, for example, the control unit 24 sets the operation mode of its own radio wave sensor 101 to any one of a high resolution mode, a continuous resolution mode, and a low resolution mode.

  More specifically, the control unit 24 sets the operation mode to the high resolution mode when the radio wave sensor 101 is activated, for example.

  For example, the control unit 24 compares the DA sampling frequency and the AD sampling frequency when the target distance Lt is equal to or less than the threshold Th1 with the DA sampling frequency and the AD sampling frequency when the target distance Lt is larger than the threshold Th1. Set each to a larger value.

  Specifically, for example, when the control unit 24 receives detection result information from the detection unit 83 that indicates that the target object Tgt has been detected and includes the target distance Lt that is larger than the threshold Th1, the control unit 24 sets the operation mode to the low resolution. Set to mode.

  At this time, the control unit 24 outputs the transmission side setting signal STL and the reception side setting signal SRL to the clock generation circuits 27T and 27R, respectively.

  For example, the control unit 24 indicates that the target Tgt has been detected, and the detection unit 83 detects detection result information including the target distance Lt that is equal to or less than the threshold Th1 and that is greater than the threshold Th2. When receiving from the above, the operation mode is set to the continuous resolution mode and the target frequency is calculated.

  More specifically, for example, the control unit 24 inputs the target distance Lt as a variable with respect to the linear function representing the straight line SL shown in FIG. A target frequency that is a value to be set as is calculated.

  For example, in the continuous resolution mode, the control unit 24 outputs a transmission side setting signal having a level for setting the frequency of the transmission side clock signal to the target frequency to the clock generation circuit 27T to set the frequency of the transmission side clock signal as the target. By setting the frequency, the DA sampling frequency is set to the target frequency.

  In addition, for example, in the continuous resolution mode, the control unit 24 outputs a reception side setting signal having a level for setting the frequency of the reception side clock signal to the target frequency to the clock generation circuit 27R to output the frequency of the reception side clock signal. Is set to the target frequency, thereby setting the AD sampling frequency to the target frequency.

  For example, the control unit 24 compares the DA sampling frequency and the AD sampling frequency when the target distance Lt is equal to or less than the threshold Th2 with the DA sampling frequency and the AD sampling frequency when the target distance Lt is larger than the threshold Th2. Set each to a larger value.

  Specifically, for example, when the control unit 24 indicates that the target Tgt has been detected and receives detection result information including the target distance Lt equal to or less than the threshold value Th2, from the detection unit 83, the control unit 24 selects the operation mode with high resolution. Set to mode.

  At this time, the control unit 24 outputs the transmission side setting signal STH and the reception side setting signal SRH to the clock generation circuits 27T and 27R, respectively.

  For example, when receiving detection result information indicating that the object Tgt has not been detected from the detection unit 83, the control unit 24 sets the low resolution mode.

  In addition, although the control part 24 calculated the target frequency by inputting the object distance Lt as a variable with respect to the linear function showing the straight line SL, it is not limited to this. The control unit 24 may calculate the target frequency by inputting the target distance Lt as a variable to a continuous function such as a curve.

  In the radio wave sensor according to the embodiment of the present invention, the control unit 24 detects the DA sampling frequency that is the sampling frequency in the DA conversion unit 22 and the AD sampling frequency that is the sampling frequency in the AD conversion unit 25. However, the present invention is not limited to this. The control unit 24 may be configured to change at least one of the DA sampling frequency and the AD sampling frequency according to the detection result by the detection unit 83.

  Preferably, the control unit 24 changes at least the AD sampling frequency of the DA sampling frequency and the AD sampling frequency according to the detection result by the detection unit 83.

  For example, the control unit 24 changes the bandwidth of the modulation signal MS generated in the signal generation unit 23 according to the changed AD sampling frequency while maintaining the DA sampling frequency.

  Specifically, for example, when changing the AD sampling frequency to ½ times while maintaining the DA sampling frequency, the control unit 24 outputs the amplitude data and the signal generation information including 2 as the speed reduction magnification to the signal generation unit. To 23. Thereby, even when the DA sampling frequency is maintained, the signal generation unit 23 generates the modulation signal MS having a double pulse width and outputs the modulation signal MS to the DA conversion unit 22.

  Further, in the radio wave sensor according to the embodiment of the present invention, the signal generation unit 23 is configured to generate the modulation signal MS having the waveform shown in FIG. 11.8 (c) on page 278 of Non-Patent Document 1. However, the present invention is not limited to this. The signal generator 23 generates a modulated signal having a waveform based on a linear FM pulse shown in FIG. 11.5 (b) on page 276 of Non-Patent Document 1 or a code sequence according to a Barker code other than N = 7. It may be a configuration.

  In the radio wave sensor according to the embodiment of the present invention, the control unit 24 sets the DA sampling frequency and the AD sampling frequency when the target distance Lt is equal to or smaller than the threshold value, and the target distance Lt is larger than the threshold value. In this case, the configuration is such that the DA sampling frequency and the AD sampling frequency are set to be larger than the DA sampling frequency. The control unit 24 reduces the DA sampling frequency and the AD sampling frequency when the target distance Lt is equal to or smaller than the threshold value compared to the DA sampling frequency and the AD sampling frequency when the target distance Lt is larger than the threshold value. The configuration may be set to a value.

  Further, in the radio wave sensor according to the embodiment of the present invention, the signal generation unit 23 is configured to generate the modulation signal MS and change the bandwidth of the modulation signal MS. However, the present invention is not limited thereto. is not. The signal generator 23 may be configured to generate a modulation signal MS having a fixed bandwidth. For example, the signal generation unit 23 may generate the modulation signal MS according to the timing of a clock signal whose frequency is fixed to fTH from a clock generation circuit different from the clock generation circuit 27T. On the other hand, the DA sampling frequency and the AD sampling frequency are changed according to the operation mode of the radio wave sensor 101, for example. Even if it is such a structure, the effect of detecting an object correctly can be produced, suppressing power consumption.

  By the way, when measuring the target distance from the pulse compression radar described in Non-Patent Document 1 to the target in the target area, the maximum detection distance and the distance resolution are the time width of the transmission pulse and Each is determined by the bandwidth of the transmission pulse.

  For example, when improving the distance resolution while maintaining the maximum detection distance, it is conceivable to perform measurement using a transmission pulse having a wide bandwidth. In this case, since the bandwidth of the transmission pulse and the bandwidth of the reflected pulse generated by reflecting the transmission pulse on the object are both wide, high-speed signal processing is required in the pulse compression radar.

  When performing high-speed signal processing in a pulse compression radar, for example, an AD (analog-digital) converter and a DA (digital-analog) converter that can operate at high speed are required. However, when the AD converter and the DA converter are operated at high speed, there is a problem that power consumption increases.

  On the other hand, in the radio wave sensor according to the embodiment of the present invention, the signal generation unit 23 generates the modulation signal MS. The DA converter 22 converts the modulation signal MS generated by the signal generator 23 into an analog signal ITAS. The transmission unit 21 converts the analog signal ITAS converted by the DA conversion unit 22 into a radio wave and transmits it to the target area A1. The receiving unit 28 receives radio waves from the target area A1 and generates reception signals IRAS and QRAS. The AD conversion unit 25 converts the reception signals IRAS and QRAS generated by the reception unit 28 into digital signals IRDS and QRDS, respectively. The detection unit 83 detects the object Tgt in the target area A1 based on the digital signals IRDS and QRDS converted by the AD conversion unit 25. Then, the control unit 24 changes at least one of the DA sampling frequency, which is the sampling frequency in the DA conversion unit 22, and the AD sampling frequency, which is the sampling frequency in the AD conversion unit 25, according to the detection result by the detection unit 83. To do.

  With such a configuration, it is possible to reduce at least one of the DA sampling frequency and the AD sampling frequency to such an extent that the detection result by the detection unit 83 is not adversely affected, thereby suppressing power consumption for sampling. it can. Therefore, it is possible to correctly detect the object while suppressing power consumption.

  In the radio wave sensor according to the embodiment of the present invention, the control unit 24 changes at least the AD sampling frequency of the DA sampling frequency and the AD sampling frequency according to the detection result by the detection unit 83.

  As described above, the power consumption can be more effectively suppressed by the configuration in which at least the AD sampling frequency, which has a larger power consumption suppression effect than when the DA sampling frequency is changed, is changed according to the detection result of the detection unit 83. can do.

  Moreover, in the radio wave sensor according to the embodiment of the present invention, the control unit 24 changes the sampling frequency according to whether or not the object Tgt is detected by the detection unit 83.

  With such a configuration, it is possible to set an appropriate sampling frequency according to whether or not the target Tgt is detected.

  In the radio wave sensor according to the embodiment of the present invention, the control unit 24 uses the sampling frequency when the object Tgt is detected by the detection unit 83 and the sampling frequency when the detection unit 83 does not detect the object Tgt. Set to a larger value than.

  With such a configuration, for example, detection accuracy is improved by detecting the object by the detection unit 83 while reducing the sampling frequency and suppressing power consumption when the object Tgt is not detected by the detection unit 83. When it is necessary, the sampling frequency can be increased.

  Further, in the radio wave sensor according to the embodiment of the present invention, the detection unit 83 is a distance from the radio wave sensor 101 to the target object Tgt in the target area A1 based on the digital signals IRDS and QRDS converted by the AD conversion unit 25. The target distance Lt is detected. Then, the control unit 24 changes the sampling frequency according to the target distance Lt detected by the detection unit 83.

  With such a configuration, an appropriate sampling frequency can be set according to the distance to the target Tgt.

  In the radio wave sensor according to the embodiment of the present invention, the control unit 24 uses the sampling frequency when the target distance Lt is equal to or less than the threshold Th1 and the sampling frequency when the target distance Lt is greater than the threshold Th1. Set to a larger value than.

  With such a configuration, when the object Tgt is detected at a position away from the radio wave sensor 101, the object Tgt is detected at a position closer to the radio wave sensor 101 while reducing power consumption by reducing the sampling frequency. Thus, for example, when it is necessary to ensure a high distance resolution, the sampling frequency can be increased.

  In the radio wave sensor according to the embodiment of the present invention, the control unit 24 changes the sampling frequency to a value corresponding to the target distance Lt detected by the detection unit 83.

  With such a configuration, it is possible to set a more appropriate sampling frequency according to the distance to the object Tgt.

  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 radio wave sensor,
A signal generation unit capable of generating a pulsed modulation signal and changing a bandwidth of the modulation signal;
A DA converter that converts the modulated signal generated by the signal generator into an analog signal;
A transmission unit that converts the analog signal converted by the DA conversion unit into a radio wave and transmits it to a target area;
A receiving unit that receives a radio wave from the target area and generates a reception signal;
An AD converter that converts the received signal generated by the receiver into a digital signal;
A detection unit for detecting an object in the target area based on the digital signal converted by the AD conversion unit;
A control unit that changes at least one of a DA sampling frequency that is a sampling frequency in the DA conversion unit and an AD sampling frequency that is a sampling frequency in the AD conversion unit according to a detection result by the detection unit;
The control unit further changes the bandwidth of the modulation signal according to the changed AD sampling frequency,
The detection unit generates a compression pulse by performing a pulse compression process using the modulation signal generated by the signal generation unit and the digital signal converted by the AD conversion unit, and generates the compressed pulse A radio wave sensor that detects a target distance that is a distance from the radio wave sensor to the target object in the target area.

[Appendix 2]
The radio wave sensor according to appendix 1, wherein the control unit changes the sampling frequency to a value corresponding to the target distance detected by the detection unit.

DESCRIPTION OF SYMBOLS 21 Transmission part 22 DA conversion part 23 Signal generation part 24 Control part 25 AD conversion part 26 Signal processing part 27T, 27R Clock generation circuit 28 Reception part 29,30 Oscillator 41I, 41Q DA converter (DAC)
42I, 42Q Low-pass filter 43I, 43Q Mixer 44 Phase shifter 45 Synthesizer 46 Mixer 47 Power amplifier 48 Transmitting antenna 61I, 61Q AD converter (ADC)
63I, 63Q mixer 64 phase shifter 66 mixer 67 low noise amplifier 68 receiving antenna 81 pulse compression processing unit 82 FFT processing unit 83 detection unit 84 buffer unit 85 aggregation unit 101 radio wave sensor 151 control device 301 radar system

Claims (6)

A signal generator for generating a modulation signal;
A DA converter that converts the modulated signal generated by the signal generator into an analog signal;
A transmission unit that converts the analog signal converted by the DA conversion unit into a radio wave and transmits it to a target area;
A receiving unit that receives a radio wave from the target area and generates a reception signal;
An AD converter that converts the received signal generated by the receiver into a digital signal;
A detection unit for detecting an object in the target area based on the digital signal converted by the AD conversion unit;
A controller that changes at least one of a DA sampling frequency that is a sampling frequency in the DA converter and an AD sampling frequency that is a sampling frequency in the AD converter according to a detection result by the detector; Radio wave sensor.   2. The radio wave sensor according to claim 1, wherein the control unit changes at least the AD sampling frequency of the DA sampling frequency and the AD sampling frequency according to a detection result by the detection unit.   The radio wave sensor according to claim 1, wherein the control unit changes the sampling frequency according to whether or not the object is detected by the detection unit.   The said control part sets the said sampling frequency when the said target object is detected by the said detection part to a larger value compared with the said sampling frequency when the said target object is not detected by the said detection part. The radio wave sensor described in 1. The detection unit detects a target distance that is a distance from the radio wave sensor to the target object in the target area based on the digital signal converted by the AD conversion unit,
The radio wave sensor according to claim 1, wherein the control unit changes the sampling frequency according to the target distance detected by the detection unit.   The said control part sets the said sampling frequency in case the said object distance is below a threshold value to a larger value compared with the said sampling frequency in case the said object distance is larger than the said threshold value. The radio wave sensor described.

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