JP5552212B2 - Radar device - Google Patents

Description

  The present invention relates to a radar apparatus, and more particularly to a radar apparatus that measures a relative position and a relative speed with respect to an object based on a radiated electromagnetic wave and a reflected wave of the electromagnetic wave.

  In recent years, in order to prevent an accident caused by a vehicle such as an automobile, a radar device for measuring an object around the vehicle has been developed and put into practical use. As a conventional radar apparatus suitable for being mounted on a vehicle, for example, a pulse radar apparatus as described in Patent Document 1 can be cited.

  The pulse radar device described in Patent Document 1 transmits a pulsed electromagnetic wave, and is relative to a measurement target based on the transmitted electromagnetic wave and a pulsed reflected wave in which the transmitted electromagnetic wave is reflected by an object. This is a pulse radar device that measures distance and relative speed. The pulse radar device described in Patent Document 1 integrates a predetermined number of pulse-like reflected wave levels, and performs measurement based on the integrated reflected wave level. This is because it is generally known that the maximum measurement range is expanded according to the number of integrations by integrating the level of the reflected wave. In general pulse radar devices, it is also generally known that distance separation performance is improved by shortening the pulse width of electromagnetic waves to be transmitted. Therefore, in order to satisfy the distance resolution and the maximum measurement range required for the pulse radar device mounted on the vehicle, the pulse width of the electromagnetic wave to be transmitted is shortened and the received pulsed reflected wave is predetermined. It has been conventionally performed to integrate the number of times.

However, in the conventional radar device as described in Patent Document 1, if the distance resolution is increased, the time required for one measurement increases. This is because if the distance resolution is increased, the number of scans for measuring the entire required measurement range increases. Further, in the conventional radar device, the time required for one measurement increases even if the number of integrations is increased. This is because if the number of integrations is increased, the number of reflected waves that must be received increases according to the number of integrations. That is, in the conventional radar device, if it is attempted to achieve both high distance separation and the maximum measurement range, the time required for one measurement becomes long.
JP 2003-329964 A

  An object of the present invention is to provide a radar device that can complete measurement in a short time while satisfying the performance required for a radar device mounted on a vehicle.

  The present invention has the following features to solve the above problems.

The present invention is a radar device for measuring the relative position and relative velocity with respect to an object based on an electromagnetic wave radiated by a radiating means and a reflected wave received by a receiving means, and based on the electromagnetic wave and the reflected wave. A first measuring means for measuring a relative position and a relative velocity with respect to the object, and a predetermined position including the relative position based on the electromagnetic wave and the reflected wave when the relative position is measured by the first measuring means. And a second measuring unit that scans only the measured range and measures a relative position and a relative velocity with respect to the object with higher resolution than the first measuring unit.

In addition, the second measuring unit is configured such that when the object whose relative position is measured by the first measuring unit is approaching at a relative speed faster than a predetermined relative speed, Relative speed may be measured immediately.

Further, the radar device of the present invention sets the passing frequency band of the filtering means to a predetermined narrow band when the filtering means for limiting the passing frequency band of the reflected wave and the first measuring means measure, And setting means for setting the pass frequency band of the filtering means to a predetermined wide band when the second measuring means performs measurement, and each of the first measuring means and the second measuring means includes electromagnetic waves, The relative position with respect to the object may be measured based on the reflected wave whose frequency band is limited to the passing frequency band set by the setting means.

The second measuring means includes an integrating means for integrating the level of the reflected wave whose pass frequency band is limited by the filtering means every time a reflected wave is received, and a first measuring means. And an integration number setting means for setting the number of integrations of the integration means according to the relative position measured by the second measurement means. The second measurement means is based on the electromagnetic wave and the reflected wave whose level is integrated by the integration means. The relative position may be measured.

The first measuring means, the relative distance and the relative speed of the object may be measured using the respective FM-CW method.

The first measuring means, the relative distance and the relative speed of the object may be measured using the respective FSK scheme.

The receiving unit includes a plurality of antennas for receiving a reflected wave, the first measurement means, based on a plurality of reflected waves received respectively by the plurality of antennas, by measuring the direction of the relative position of the object Also good .

The first measurement means, based on a plurality of reflected wave phase respectively received by the plurality of antennas may be measured in the direction of the relative position of the object.

Further, the first measuring means may measure the direction of the relative position of the object based on the levels of the plurality of reflected waves respectively received by the plurality of antennas.

The second measuring means may measure the relative distance between the object using pulsed Doppler system.

The second measuring means may measure the relative distance between the object using PSK scheme.

The receiving unit includes a plurality of antennas for receiving a reflected wave, the second measuring means, based on a plurality of reflected waves received respectively by the plurality of antennas to measure the direction of the relative position of the object May be .

The second measuring means, based on a plurality of reflected wave phase respectively received by the plurality of antennas, by using the phase comparison monopulse system, it may be measured in the direction of the relative position of the object.

Further, the second measuring means may measure the direction of the relative position with respect to the object using the amplitude comparison monopulse method based on the levels of the plurality of reflected waves respectively received by the plurality of antennas.

Further, the radar device according to the present invention may be mounted on a moving body.

The radar device according to the present invention may be mounted on a vehicle.

  ADVANTAGE OF THE INVENTION According to this invention, the radar apparatus which can complete a measurement in a short time can be provided, satisfy | filling the performance required for the radar apparatus mounted in a vehicle.

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of a radar apparatus 1 according to the first embodiment of the present invention. The radar apparatus 1 shown in FIG. 1 includes a reference signal generating unit 101, a modulating unit 102, a branching unit 103, a radiating unit 104, a first receiving unit 105a, a second receiving unit 105b, and a 90 degree shift. The phase unit 106, the first mixing unit 107a, the second mixing unit 107b, the third mixing unit 107c, the fourth mixing unit 107d, the first variable band limiting filter 108a, and the second A variable band limiting filter 108b, a third variable band limiting filter 108c, a fourth variable band limiting filter 108d, and a control processing unit 109 are provided. Hereinafter, an outline of the operation of each component of the radar device 1 according to the present embodiment will be described.

  The reference signal generation unit 101 generates a reference signal having a frequency corresponding to an instruction given from the control processing unit 109.

  In response to an instruction given from the control processing unit 109, the modulation unit 102 generates a signal obtained by modulating the reference signal generated by the reference signal generation unit 101.

  The branching unit 103 outputs the signal generated by the modulation unit 102 at the timing according to the instruction given from the control processing unit 109, the radiation unit 104, the 90-degree phase shift unit 106, the first mixing unit 107a, and the third mixing unit. Distributed to the unit 107c.

  The radiating unit 104 radiates the signal distributed by the branching unit 103 as an electromagnetic wave.

  The first receiving unit 105a and the second receiving unit 105b are arranged on substantially the same horizontal line, and each receive a reflected wave in which the electromagnetic wave radiated by the radiating unit 104 is reflected by the object.

  The 90-degree phase shift unit 106 generates a signal in which the phase of the signal distributed by the branch unit 103 is shifted by 90 degrees. More specifically, the 90-degree phase shift unit 106 generates a signal obtained by advancing or delaying the phase of the signal distributed by the branching unit 103 by 90 degrees.

  The first mixing unit 107a to the fourth mixing unit 107d are the reflected wave respectively received by the first receiving unit 105a and the second receiving unit 105b and the signal distributed by the branching unit 103 or 90 degrees. A signal obtained by mixing the signal generated by the phase shift unit 106 is generated.

  The first variable band limiting filter 108a to the fourth variable band limiting filter 108d limit the pass frequency bands of the signals generated by the first mixing unit 107a to the fourth mixing unit 107d, respectively, and the control processing unit 109. Only the signal in the frequency band indicated by is passed.

  The control processing unit 109 measures the relative position and relative speed with the object while switching between the first measurement method and the second measurement method. More specifically, the control processing unit 109 measures the relative position and relative speed with respect to the object using the first measurement method, and determines the vicinity of the object based on the measurement result according to the first measurement method. Measurement is performed using a second measurement method having a higher resolution than the first measurement method. The control processing unit 109 gives an instruction to each of the above-described components in order to measure the relative position and relative speed with respect to the object while switching between the first measurement method and the second measurement method. Detailed descriptions of the first measurement method, the second measurement method, and the control processing unit 109 will be described later.

  The above is the outline of each component of the radar device 1 according to the present embodiment. In the present invention, the relative distance to the object and the direction (angle) in which the object exists are measured as the relative position to the object. The direction in which the object exists corresponds to the direction of the relative position of the object on the horizontal plane as viewed from the radar device 1.

  Next, the first measurement method used in the radar apparatus 1 according to this embodiment will be described. FIG. 2 is a diagram illustrating the frequency of electromagnetic waves radiated from the radiating unit 104 and the timing of radiating electromagnetic waves of the respective frequencies in the first measurement method.

  In the first measurement method, the frequency of the electromagnetic wave radiated from the radiating unit 104 is switched in stages to a plurality of different frequencies as shown in FIG. Measure each existing direction. In the description of this embodiment, as an example, the number of frequencies to be switched is three. The three frequencies are fr1, fr2, and fr3, respectively.

  An operation for radiating an electromagnetic wave when the radar apparatus 1 performs the measurement by the first measurement method will be described. In response to an instruction given from the control processing unit 109, the reference signal generation unit 101 generates a reference signal having a predetermined frequency as the frequency of the carrier wave of the electromagnetic wave in the first measurement method.

  The modulation unit 102 generates a signal obtained by modulating the reference signal generated by the reference signal generation unit 101 at a timing and an interval according to an instruction given from the control processing unit 109, so that the timing shown in FIG. And the signal which switches to a mutually different frequency by the space | interval ts is produced | generated. Note that the interval ts for generating the signals of the respective frequencies is not necessarily constant as shown in FIG.

  In response to an instruction given from the control processing unit 109, the branching unit 103 controls the modulation unit 102 for each of the radiation unit 104, the 90-degree phase shift unit 106, the first mixing unit 107a, and the third mixing unit 107c. Distribute the signal generated by More specifically, when the branching unit 103 performs the measurement by the first measurement method, the branching unit 103 outputs the signal generated by the modulation unit 102 to the radiating unit 104, the 90-degree phase shift unit 106, the first mixing unit 107a, and the third mixing unit 107a. This is always distributed to each of the mixing sections 107c.

  The radiating unit 104 radiates the signal distributed by the branching unit 103 as an electromagnetic wave. As a result, electromagnetic waves that switch to different frequencies as shown in FIG.

  Next, an operation when the radar apparatus 1 receives a reflected wave during measurement by the first measurement method will be described. The reflected waves obtained by reflecting the electromagnetic waves radiated from the radiating unit 104 by the object are received by the first receiving unit 105a and the second receiving unit 105b, respectively.

  The 90-degree phase shift unit 106 generates a signal in which the phase of the signal distributed by the branch unit 103 is shifted by 90 degrees.

  The first mixing unit 107a generates a signal obtained by mixing the signal distributed by the branching unit 103 and the reflected wave received by the first receiving unit 105a. The second mixing unit 107b generates a signal obtained by mixing the signal generated by the 90-degree phase shift unit 106 and the reflected wave received by the first receiving unit 105a. The third mixing unit 107c generates a signal obtained by mixing the signal distributed by the branching unit 103 and the reflected wave received by the second receiving unit 105b. The fourth mixing unit 107d generates a signal obtained by mixing the signal generated by the 90-degree phase shift unit 106 and the reflected wave received by the second receiving unit 105b.

  That is, when the measurement by the first measurement method is performed, the frequency of the signal mixed by the first mixing unit 107a to the fourth mixing unit 107d with the reflected wave is the frequency of the electromagnetic wave radiated from the radiating unit 104. Is equal to More specifically, when the electromagnetic wave having the frequency fr1 is radiated from the radiating unit 104, the frequency of the signal mixed by the first mixing unit 107a to the fourth mixing unit 107d with the reflected wave is the frequency fr1. When the electromagnetic wave having the frequency fr2 is radiated from the radiating unit 104, the frequency of the signal mixed by the first mixing unit 107a to the fourth mixing unit 107d with the reflected wave is the frequency fr2. When the electromagnetic wave having the frequency fr3 is emitted from the radiating unit 104, the frequency of the signal mixed by the first mixing unit 107a to the fourth mixing unit 107d with the reflected wave is the frequency fr3.

  In addition, the signal produced | generated by the 1st mixing part 107a-the 4th mixing part 107d turns into a signal (beat frequency signal) which has the difference frequency of the signal which each mixing part acquired.

  The first variable band limiting filter 108a to the fourth variable band limiting filter 108d are first signals instructed from the control processing unit 109 among the signals generated by the first mixing unit 107a to the fourth mixing unit 107d. Only signals in a frequency band suitable for the measurement method are allowed to pass through. Note that the frequency band suitable for the first measurement method refers to the maximum measurement range, the distance resolution, in addition to the range of the Doppler shift amount generated when the electromagnetic wave radiated from the radiation unit 104 is reflected by the object. In addition, a predetermined frequency band in consideration of speed resolution or the like, or a relatively narrow narrow band may be used.

  The control processing unit 109 performs A / D conversion processing on the signals that have passed through the first variable band limiting filter 108a to the fourth variable band limiting filter 108d, respectively, and then performs IQ detection (orthogonal detection) or FFT (Fast Fourier). Transform: Fast Fourier transform).

  More specifically, the control processing unit 109 sets the first set of signals that have passed through the first variable band limiting filter 108a and the second variable band limiting filter 108b, among the signals that have undergone A / D conversion processing. IQ detection is performed based on this, and FFT processing is performed on the signal obtained by IQ detection. In addition, the control processing unit 109 performs IQ based on a pair of second signals that have passed through the first variable band limiting filter 108c and the second variable band limiting filter 108d, respectively, among the signals that have undergone A / D conversion processing. Detection is performed, and FFT processing is performed on a signal obtained by IQ detection. And the control process part 109 measures the relative distance with respect to a target object, a relative speed, and the direction in which a target object exists, respectively by further calculating based on these process results.

  Note that the control processing unit 109 also performs a conventionally known two-dimensional FFT process or the like on each of the first and second signal sets described above, so that each set is set as described above. On the other hand, it is possible to obtain the same processing result as when FFT processing is performed on a signal obtained by performing IQ detection. The same processing result can be obtained in the same way when measuring by the second measurement method.

  The calculation process of the control processing unit 109 for measuring the relative distance to the object in the first measurement method, the relative speed, and the direction in which the object exists will be described.

  The radar apparatus 1 according to the present embodiment includes two receiving units, a first receiving unit 105a and a second receiving unit 105b. In the relative distance measurement method in the first measurement method, the relative distance can be measured based on the reflected wave received by only one of the reception units included in the radar device 1. In the description of this embodiment, a case where the relative velocity is measured based on the reflected wave received by the first receiving unit 105a will be described as an example.

  In order to describe the calculation process of the control processing unit 109 for measuring the relative distance to the object in the first measurement method, the reflected wave received by the first receiving unit 105a will be described first. In the first measurement method, electromagnetic waves of frequencies fr1 and fr2 are reflected by the object, and mathematical expressions showing examples of reflected waves received by the first receiving unit 105a are Expressions (1) and (2), respectively. is there.

  In the above formulas (1) and (2), Vfr1 and Vfr2 are examples of reflected waves in which electromagnetic waves radiated at the frequency fr1 and the frequency fr2, respectively, are reflected by the object. R is a relative distance to the object. Further, fd1 and fd2 are Doppler frequencies of reflected waves obtained by reflecting electromagnetic waves radiated at the frequencies fr1 and fr2, respectively, from the object. C is the speed of light.

  The first mixing unit 107a and the second mixing unit 107b are the reflected wave received by the first receiving unit 105a and the second receiving unit 105b, the signal distributed from the branching unit 103, and the 90 degree phase shift unit. The signal generated by 106 is mixed.

  More specifically, when the electromagnetic wave having the frequency fr1 is radiated from the radiating unit 104, the first mixing unit 107a has a signal having the frequency fr1 distributed by the branching unit 103 and a reflected wave Vfr1 for the signal having the frequency fr1. To generate a mixed signal. In addition, the second mixing unit 107b receives a signal (frequency fr1) generated by the 90-degree phase shift unit 106 and a reflected wave Vfr1 with respect to the signal of the frequency fr1 when the electromagnetic wave of the frequency fr1 is radiated from the radiating unit 104. To generate a mixed signal. On the other hand, when the electromagnetic wave having the frequency fr2 is radiated from the radiating unit 104, the first mixing unit 107a mixes the signal having the frequency fr2 distributed by the branching unit 103 and the reflected wave Vfr2 with respect to the signal having the frequency fr2. Generate a signal. In addition, when the electromagnetic wave having the frequency fr2 is radiated from the radiating unit 104, the second mixing unit 107b reflects the signal (frequency fr2) generated by the 90-degree phase shift unit 106 and the reflected wave Vfr2 for the signal having the frequency fr2. To generate a mixed signal.

  When the electromagnetic waves having the frequency fr1 and the frequency fr2 are radiated, examples of mathematical expressions indicating the low-frequency components of the signal generated by the first mixing unit 107a are respectively expressed by the expressions (3) and (4). is there.

  The signal Vd1 in Expression (3) indicates a signal generated by the first mixing unit 107a when the electromagnetic wave having the frequency fr1 is radiated from the radiating unit 104. A signal Vd2 in Expression (4) indicates a signal generated by the first mixing unit 107a when the electromagnetic wave having the frequency fr2 is radiated from the radiating unit 104. An example of a mathematical expression of the signal generated by the second mixing unit 107b is similarly expressed by Expression (3) and Expression (4). However, in the present embodiment, the first mixing unit 107 a mixes the signal branched from the branching unit 103 and the reflected wave, whereas the second mixing unit 107 b is generated by the 90-degree phase shift unit 106. The difference is that the reflected signal and the reflected wave are mixed. However, since the control processing unit 109 performs the FFT processing described later in consideration of this different point, an erroneous measurement result is not obtained.

  The phase difference between the signal Vd1 and the signal Vd2 can be derived from the equations (3) and (4). An example of a mathematical expression indicating the phase difference between the signal Vd1 and the signal Vd2 is shown as Expression (5). Equation (5) is derived by assuming that the Doppler frequency fd1 and Doppler frequency fd2 in Equations (3) and (4) are substantially equal. The reason that the Doppler frequency fd1 and the Doppler frequency fd2 can be regarded as being substantially equal is fd1 / fd2 = fr1 / fr2, and the difference between fr1 and fr2 is sufficiently small compared to the respective values, so it is considered that they are substantially equal. Because it can.

  Then, equation (6) shown below can be derived by modifying equation (5).

式（６）から明らかなように、信号Ｖｄ１と信号Ｖｄ２との位相差Δφを求めることができれば、対象物との相対距離Ｒを測定することができる。

As is clear from the equation (6), if the phase difference Δφ between the signal Vd1 and the signal Vd2 can be obtained, the relative distance R to the object can be measured.

  The phase difference Δφ can be obtained by performing IQ detection and FFT processing based on the signals mixed by the first mixing unit 107a and the second mixing unit 107b, respectively. More specifically, the control processing unit 109 converts the signal having passed through the first variable band limiting filter 108a and the second variable band limiting filter 108b during the period in which the signal of the frequency fr1 is being radiated from the radiating unit 104. Based on this, IQ detection and FFT processing are performed to obtain the phase of the signal Vd1. Here, the phase of the signal Vd1 is defined as a phase φ1. Further, the control processing unit 109 performs IQ based on the signals that have passed through the first variable band limiting filter 108a and the second variable band limiting filter 108b during the period in which the signal of the frequency fr2 is radiated from the radiating unit 104. The phase of the signal Vd2 is obtained by performing detection and FFT processing. Here, the phase of the signal Vd2 is defined as a phase φ2. The control processing unit 109 calculates the difference between the phase φ1 and the phase φ2 as the above-described phase difference Δφ. Then, the relative distance from the object is calculated and measured by substituting the calculated phase difference Δφ into the equation (6).

  As in the case of obtaining the phase difference Δφ between the signal Vd1 and the signal Vd2, the control processing unit 109 determines the level of the two signals generated based on the reflected wave with respect to the electromagnetic wave with the frequency fr2 and the reflected wave with respect to the electromagnetic wave with the frequency fr3. The relative distance from the object can also be measured by calculating the phase difference. The relative distance to the object can also be measured by calculating the phase difference between the two signals generated based on the reflected wave with respect to the electromagnetic wave with the frequency fr1 and the reflected wave with respect to the electromagnetic wave with the frequency fr3. Hereinafter, the phase difference between the reflected wave for the electromagnetic wave having the frequency fr1 and the reflected wave for the electromagnetic wave having the frequency fr2 is expressed as Δφ1, the reflected wave for the electromagnetic wave having the frequency fr2, and the reflected wave for the electromagnetic wave having the frequency fr3, respectively. The phase difference between the generated signals is Δφ2, and the phase difference between the signals generated based on the reflected wave with respect to the electromagnetic wave with the frequency fr1 and the reflected wave with respect to the electromagnetic wave with the frequency fr3 is Δφ3. The relative distances obtained using the phase differences Δφ1 to Δφ3 are set as relative distances R1 to R3, respectively.

  The control processing unit 109 obtains the above-described relative distances R1 to R3 while switching the frequency of the electromagnetic wave radiated from the radiating unit 104 as shown in FIG. Then, the control processing unit 109 calculates a relative distance obtained by averaging the relative distances R1 to R3, and sets the averaged relative distance as a more accurate relative distance to the object. This is an explanation of the method for measuring the relative distance to the object in the first measurement method. Next, a method for measuring the relative speed with the object in the first measurement method will be described.

  In the first measurement method, the relative velocity with the object can be measured by the following equation (7).

  As is clear from the equation (7), if the Doppler frequency fd1 or the Doppler frequency fd2 can be obtained, the relative speed with the object can be measured. The Doppler frequency fd1 and the Doppler frequency fd2 can be obtained by performing FFT processing on the signal Vd1 and the signal Vd2, respectively. More specifically, the control processing unit 109 obtains the Doppler frequency fd1 or the Doppler frequency fd2 by performing FFT processing on the signal Vd1 and the signal Vd2 that have been subjected to IQ detection. Then, the control processing unit 109 substitutes the obtained Doppler frequency fd1 or Doppler frequency fd2 into Expression (7), and measures the relative speed with the object.

  The above is the description of the method for measuring the relative distance and the relative speed with the object in the first measurement method. When the control processing unit 109 measures the relative speed in the first measurement method, the control processing unit 109 measures the relative distance in the first measurement method as the signals Vd1 and Vd2 subjected to IQ detection for obtaining the Doppler frequency. Needless to say, each of the signals subjected to IQ detection may be used.

  Further, the above-described method for measuring the relative distance and relative velocity with respect to the object may be generally called an FSK method. However, the method that can be used as the first measurement method is not limited to the FSK method, and the FM-CW method or the two-frequency CW method is used to measure the relative distance and relative velocity with respect to the object. May be.

  Further, the Doppler frequency fd1 and the Doppler frequency fd2 described above are the Doppler frequencies of the signals Vd1 and Vd2 generated based on the reflected wave when the electromagnetic waves of the frequency fr1 and the frequency fr2 are radiated from the radiating unit 104, respectively. Similarly, the control processing unit 109 uses the Doppler frequency of the signal generated based on the reflected wave when the electromagnetic wave having the frequency fr3 is radiated from the radiating unit 104 in the measurement by the first measurement method. However, it goes without saying that the relative speed with the object can be obtained.

  In the method of measuring the relative distance and the relative speed in the first measurement method described above, even if the frequency difference between the frequency fr1 and the frequency fr2 and the frequency difference between the frequency fr2 and the frequency fr3 are reduced to several hundred kHz, respectively. A wide range of several hundred meters can be set as the maximum measurement range. The fact that the frequency difference can be reduced means that a VCO (Voltage Controlled Oscillator) that can be oscillated is required when the reference signal generated by the reference signal generation unit 101 is modulated by the modulation unit 102. Indicates that it may be narrow. A VCO having a narrow oscillating frequency band can generally be realized at a low cost. That is, according to the method of measuring the relative distance and the relative speed in the first measurement method described above, it is possible to perform measurement with a wide maximum measurement range at low cost.

  Next, a measurement method in the direction in which the object exists in the first measurement method will be described. FIG. 3 is a diagram illustrating a method when measuring a direction in which an object exists in the first measurement method. In FIG. 3, a part of the block diagram shown in FIG. 1 is cited. In the first measurement method, as described above, measurement is performed by radiating electromagnetic waves while switching the three frequencies (fr1, fr2, and fr3). However, in the following description, one frequency is used for convenience of explanation. A case where the direction in which the object is present is measured during the period in which the electromagnetic wave fr1 is emitted will be described as an example.

  As shown in FIG. 3, the reflected waves obtained by reflecting the electromagnetic wave having the frequency fr1 radiated from the radiating unit 104 are received by the first receiving unit 105a and the second receiving unit 105b, respectively. The reflected wave received by the first receiver 105a is Rf1, and the reflected wave received by the second receiver 105b is Rf2.

  Here, as shown in FIG. 3, assuming that a reflected wave arrives from the direction of angle ψ, that is, an object exists in the direction of angle ψ, each of first receiving unit 105a and second receiving unit 105b There is a difference in the distance from the object to the object by the distance b. Therefore, the phase difference corresponding to the distance b between the reflected wave Rf1 received by the first receiver 105a and the reflected wave Rf2 received by the second receiver 105b, in other words, the first A phase difference corresponding to the interval d between the receiving unit 105a and the second receiving unit 105b occurs. This phase difference is defined as a phase difference Δθ. If the phase difference Δθ can be obtained, the angle ψ, that is, the direction in which the object exists can be calculated and measured by the following equation (8).

  This phase difference Δθ can be obtained by performing IQ detection and FFT processing on the reflected wave Rf1 and the reflected wave Rf2, respectively. IQ detection for the reflected wave Rf1 and the reflected wave Rf2 can be performed using the 90-degree phase shift unit 106 and the first mixing unit 107a to the fourth mixing unit 107d.

  More specifically, as described above, the first mixing unit 107a generates a signal obtained by mixing the reflected wave Rf1 and the signal having the frequency fr1 distributed by the branching unit 103. The second mixing unit 107b generates a signal obtained by mixing the reflected wave Rf1 and the signal (frequency fr1) generated by the 90-degree phase shift unit 106. The third mixing unit 107c generates a signal obtained by mixing the reflected wave Rf2 and the signal having the frequency fr1 distributed by the branching unit 103. The fourth mixing unit 107d generates a signal obtained by mixing the reflected wave Rf2 and the signal (frequency fr1) generated by the 90-degree phase shift unit 106.

  Then, the control processing unit 109 transmits the signals generated by the first mixing unit 107a to the fourth mixing unit 107d via the first variable band limiting filter 108a to the fourth variable band limiting filter 108d, respectively. get. The control processing unit 109 then generates signals generated based on the reflected wave Rf1 and the reflected wave Rf2 via the circuit including the 90-degree phase shift unit 106 and the first mixing unit 107a to the fourth mixing unit 107d. The phase difference Δθ is obtained by obtaining and performing IQ detection and FFT processing based on the obtained signal as described above. Then, the control processing unit 109 calculates and measures the direction in which the object exists by substituting the obtained phase difference Δθ into the equation (8).

  The above is the description of the method for measuring the direction in which the object is present in the first measurement method. In the description of the method for measuring the direction in which the object exists in the first measurement method described above, based on the phase difference of the reflected waves respectively received by the first receiver 105a and the second receiver 105b. The direction in which the object exists was measured. However, the radar apparatus 1 according to the present embodiment measures the direction in which the object exists based on the difference in the level of the reflected wave received by the first receiving unit 105a and the second receiving unit 105b. Also good.

  In the above-described method for measuring the direction in which the object is present in the first measurement method, measurement is performed based on the reflected waves received by the two receiving units, the first receiving unit 105a and the second receiving unit 105b. The case where it does is demonstrated as an example. However, when measuring the direction in which the object is present in the radar apparatus 1 according to the present embodiment, the direction in which the object is present may be measured using three or more receiving units.

  Next, the second measurement method used for the radar apparatus 1 according to the present embodiment will be described. FIG. 4 is a timing chart for explaining the operation for the radar device 1 to measure the relative position and the relative velocity with respect to the object in the second measurement method. More specifically, FIG. 4A shows the timing at which the radiating unit 104 radiates an electromagnetic wave having an intermittent waveform. FIG. 4B shows signal distribution timings to the 90-degree phase shift unit 106, the first mixing unit 107a, and the third mixing unit 107c. FIG. 4C shows an example of timing at which the first receiving unit 105a or the second receiving unit 105b receives the reflected wave. FIG. 4D is generated by mixing the signal distributed by the branching unit 103 and the reflected wave received by at least one of the first receiving unit 105a and the second receiving unit 105b. Signal level (correlation).

  An operation for radiating an electromagnetic wave when the radar apparatus 1 performs measurement by the second measurement method will be described. The reference signal generation unit 101 generates a reference signal having a predetermined frequency as the frequency of the carrier wave in the second measurement method in response to an instruction given from the control processing unit 109.

  When measuring by the second measurement method, the modulation unit 102 transmits the reference signal generated by the reference signal generation unit 101 to the branching unit 103 without modulating it according to an instruction from the control processing unit 109. To do.

  As shown in FIG. 4 (a), the branching unit 103 transmits the signal transmitted from the modulation unit 102 in accordance with an instruction given from the control processing unit 109 every time the start timing of the radiation interval Hk arrives. To distribute to the radiating section 104. In order to make the reference signal distributed to the radiating section 104 into an intermittent waveform as shown in FIG. 4A, a switching circuit is provided on the transmission path of the reference signal provided inside the branch section 103. In response to an instruction from the control processing unit 109, the branching unit 103 switches the open state and the closed state of the switching circuit at the timing and interval shown in FIG. The signal may be intermittently transmitted to the radiating unit 104. Alternatively, a signal having an intermittent waveform may be generated by mixing a rectangular pulse or a Gaussian pulse generated at a predetermined timing with a reference signal.

  Each time the signal is distributed from the branching unit 103, the radiating unit 104 radiates the distributed signal as an electromagnetic wave. Thereby, the electromagnetic wave of an intermittent waveform is radiated | emitted from the radiation | emission part 104 at the timing (start timing of the radiation | emission space | interval Hk) and space | interval Ph which are shown to Fig.4 (a).

  Next, an operation when the radar apparatus 1 receives a reflected wave during measurement by the second measurement method will be described. The reflected waves obtained by reflecting the electromagnetic waves radiated from the radiating unit 104 by the object are received by the first receiving unit 105a and the second receiving unit 105b, respectively.

  In response to an instruction given from the control processing unit 109, the branching unit 103 performs modulation at a predetermined interval Bh when the start timings of the time difference td1 to the time difference td4 arrive as shown in FIG. The signal generated by 102 is distributed to the 90-degree phase shift unit 106, the first mixing unit 107a, and the third mixing unit 107c, respectively.

  The time difference td1 to the time difference td4 is set so that the signal repeatedly distributed to the 90-degree phase shift unit 106, the first mixing unit 107a, and the third mixing unit 107c becomes longer each time the electromagnetic wave is radiated from the radiating unit 104. Each is predetermined. More specifically, the timing at which signals are first distributed to the 90-degree phase shift unit 106, the first mixing unit 107a, and the third mixing unit 107c is the start timing at which electromagnetic waves are radiated from the radiating unit 104, The time difference td1 has elapsed from the start timing of the interval Ph. The timing at which the signal is distributed to the 90-degree phase shift unit 106, the first mixing unit 107a, and the third mixing unit 107c for the second time is when the time difference td2 has elapsed from the start timing of the interval Ph. This time difference td2 is twice as long as the time difference td1. The timing when the signal is distributed to the 90-degree phase shift unit 106, the first mixing unit 107a, and the third mixing unit 107c for the third time is when the time difference td3 has elapsed from the start timing of the interval Ph. This time difference td3 is three times as long as the time difference td1. The timing at which the signal is distributed to the 90-degree phase shift unit 106, the first mixing unit 107a, and the third mixing unit 107c for the fourth time is when the time difference td4 has elapsed from the start timing of the interval Ph. This time difference td4 is four times as long as the time difference td1.

  The timing at which the signal is distributed to the 90-degree phase shift unit 106, the first mixing unit 107a, and the third mixing unit 107c for the fifth time is the time difference td1 from the start timing of the interval Ph. That is, when the signal is distributed four times to the radiating unit 104, the next time difference becomes the first time difference td1. That is, as an example, the radar apparatus 1 according to the present embodiment, when measuring by the second measurement method, emits 4 degrees of electromagnetic waves, 4 degrees of 90 degrees phase shift section 106, the first mixing section 107a, and the first mixing section 107a. The period necessary for distributing the signals to the three mixing units 107c is set as one period T, and the operation in the period T is repeated. The reason why the branching unit 103 changes the timing of distributing the signal to the 90-degree phase shift unit 106, the first mixing unit 107a, and the second mixing unit 107c as shown in FIG. 4B will be described later. .

  The 90-degree phase shift unit 106 generates a signal in which the phase of the signal distributed by the branch unit 103 is shifted by 90 degrees.

  Each of the first mixing unit 107 a to the fourth mixing unit 107 d generates a signal obtained by mixing the reflected wave and the signal distributed by the branching unit 103. In the following description, the first receiving unit 105a and the second receiving unit 105b when the time difference td2 has elapsed since the signal was distributed to the radiating unit 104 for the second time in one cycle T described above. The description will be continued assuming that the reflected wave reflected by the object is received.

  The first variable band limiting filter 108a to the fourth variable band limiting filter 108d are instructed from the control processing unit 109 among the signals generated by the first mixing unit 107a to the fourth mixing unit 107d, respectively. Only a signal in a frequency band suitable for the determined second measurement method is allowed to pass.

  The control processing unit 109 acquires signals that have passed through the first variable band limiting filter 108a to the fourth variable band limiting filter 108d, and performs A / D conversion processing. Then, the control processing unit 109 performs processing different from the first measurement method using the processing result, so that the relative position, the relative speed, and the target object exist in the second measurement method. Measure each direction.

  Next, calculation processing of the control processing unit 109 for measuring the relative distance to the object in the second measurement method will be described. Note that the calculation processing of the control processing unit 109 for measuring the relative speed with the object and the direction in which the object exists in the second measurement method will be described later.

  In the second measurement method, the relative distance to the object is measured based on the time from when the electromagnetic wave is radiated once until the reflected wave of the electromagnetic wave is received. An example of a mathematical formula for obtaining the relative distance to the object when this time is Δtd is shown below as Equation (9).

  In the present embodiment, in order to obtain the time Δtd, as described above, the branching unit 103 distributes the signal to the 90-degree phase shift unit 106, the first mixing unit 107a, and the third mixing unit 107c. Change to ~ td4. The reason for this will be described.

  In the radar apparatus 1 according to the present embodiment, as described above, a signal obtained by mixing the signal distributed by the branching unit 103 and the reflected waves respectively received by the first receiving unit 105a and the first receiving unit 105b. Is generated by the first mixing unit 107a to the fourth mixing unit 107d. Therefore, when the timing at which the first mixing unit 107a to the fourth mixing unit 107d acquire the signal distributed by the branching unit 103 from the branching unit 103 and the timing at which the reflected wave reflected by the target object is acquired. Only, the level of the signal generated by each mixing unit is higher than when the timings of each other do not match. That is, the level of the signal generated by the first mixing unit 107a to the fourth mixing unit 107d and passed from the first variable band limiting filter 108a to the fourth variable band limiting filter 108d to the control processing unit 109 is determined in advance. When it is higher than the threshold value, the control processing unit 109 can determine that the reflected wave reflected by the object has been received.

  The timing at which the reflected wave reflected by the object is received, that is, the timing at which the level of the signal that has passed to the control processing unit 109 becomes higher than a predetermined threshold is 90 after the electromagnetic wave is radiated by the radiating unit 104. This is a timing at which one of the time differences td1 to td4 has elapsed from the timing at which the signal is distributed to the first phase shift unit 106, the first mixing unit 107a, and the third mixing unit 107c, that is, the start timing of the interval Ph. The start timing of the interval Ph is the timing at which electromagnetic waves are radiated from the radiating unit 104. Therefore, the time difference that coincides with the timing at which the reflected wave reflected by the object is received among the time differences td1 to td4 described above is the time from when the electromagnetic wave is emitted until the reflected wave reflected by the object is received. . That is, the control processing unit 109 identifies the time difference when it is determined that the reflected wave reflected by the object has been received from the time differences td1 to td4, and uses the equation (9) with the identified time difference as the time Δtd. Measure the relative distance to the object.

  In the above description, when the time difference td1 to the time difference td4 changes in order from the time difference td1 to the time difference td4 in one cycle T, the time difference td1 to the time difference td4 changes again in order in the next cycle T. In the second measurement method, the relative distance to the object is obtained from the time difference that coincides with the timing at which it is determined that the reflected wave is received among these time differences. That is, these time differences td1 to td4 correspond to relative distances from the object, respectively. Hereinafter, the relative distances corresponding to the above-described time differences are referred to as range bins. And in the above-mentioned one period T, measuring the relative distance from the object while changing the time difference means that the range bins corresponding to these time differences are sequentially scanned from the range bin close to the radar device 1. Become. Therefore, the radar apparatus 1 according to the present embodiment scans all the range bins included in the measurement range once in order from the minimum measurement distance to the maximum measurement distance in one cycle T, and the relative distance from the target object. The operation to measure is repeated. The length of one range bin corresponds to the relative distance resolution in the second measurement method of the radar apparatus 1.

  The above is the description of the method for measuring the relative distance to the object in the second measurement method. This measurement method is sometimes called a pulse Doppler method. Further, in the radar device 1 according to the present embodiment, the relative distance of the object may be measured using a generally known PSK method at the time of measurement by the second measurement method. In the above description, the case where the length of the time difference td1 to the time difference td4 is an integral multiple of the length of the interval Ph (the length of the interval Bh) has been described as an example. However, the length of the time difference td1 to the time difference td4 is not limited to an integral multiple of the length of the interval Ph (the length of the interval Bh), and may be an integral multiple of a certain constant. By selecting a constant that shortens the length of the time difference td1 to the time difference td4, the number of range bins included in the measurement range increases, and the resolution of the relative distance increases.

  Next, a method for measuring the relative speed with the object in the second measurement method will be described with reference to FIG. FIG. 4 shows the operation of the radar device 1 in two periods T among the operations of the radar device 1. FIG. 4D shows, as an example, a case where an object exists at a relative distance for receiving a reflected wave at a time corresponding to the second range bin in each radiation interval Hk. That is, in the period shown in FIG. 4D, the control processing unit 109 determines that the reflected wave has been received only twice. Hereinafter, the reflected waves determined to be received by the control processing unit 109 will be referred to as the first received wave and the second received wave, respectively. In the second measurement method, an example of a mathematical formula for measuring the relative velocity based on the reflected wave received for the first time and the reflected wave received for the second time is shown in Expression (10).

  In Expression (10), Δξ represents a phase difference between the phase of the reflected wave received first time and the phase of the reflected wave received second time. Δtv indicates the time from the first reception of the reflected wave to the second reception of the reflected wave. The control processing unit 109 performs A / D conversion on the signal based on the reflected wave received first time, and then performs IQ detection and FFT processing to obtain the phase of the reflected wave received first time. Then, the control processing unit 109 performs A / D conversion on the signal based on the reflected wave received for the second time, and then performs IQ detection and FFT processing to obtain the phase of the reflected wave received for the second time. The control processing unit 109 obtains a phase difference Δξ between the phase of the reflected wave received first time and the phase of the reflected wave received second time. Further, the control processing unit 109 obtains a time difference Δtv between the time when the first reflected wave is received and the time when the second reflected wave is received. Then, the control processing unit 109 calculates and measures the relative speed with respect to the object by substituting the obtained phase difference Δξ and time difference Δtv into Expression (10).

  The above is the description of the method for measuring the relative speed with the object in the second measurement method. According to this method, since the relative velocity with respect to the object can be measured by receiving the reflected wave at least twice, the measurement time can be shortened. In addition, the method of measuring the relative speed with the object is generally called a pulse pair method. Also, the second measurement method uses the same configuration as that of the first measurement method described above, so that IQ detection can be performed similarly to the first measurement method. In this embodiment, in order to perform IQ detection also in the second measurement method, the sign of the component corresponding to the relative speed with the actual object is specified among the signs of the positive and negative frequency components included in the Doppler frequency component. Can do. That is, in the method for measuring the relative speed with the object in the second measurement method, not only the relative speed is measured, but it is simultaneously determined whether the object is approaching or moving away from the radar device 1. be able to.

  Next, a method for measuring the direction in which the object exists in the second measurement method will be described. In the second measurement method, measurement is performed by radiating an electromagnetic wave having an intermittent waveform from the radiating unit 104 as shown in FIG. The electromagnetic wave radiated from the radiating unit 104 is an intermittent waveform signal having a partial waveform of the reference signal generated by the reference signal generating unit 101. That is, the electromagnetic wave radiated from the radiating unit 104 in the second measurement method is a signal having a phase similar to the electromagnetic wave radiated from the radiating unit 104 in the first measurement method. Therefore, in the present embodiment, as a method for measuring the direction in which the object exists in the second measurement method, a method similar to the method for measuring the direction in which the object exists in the first measurement method is used. To do. That is, an object exists in the same manner as the first measurement method based on the reflected waves respectively received by the first receiving unit 105a and the second receiving unit 105b each time one range bin is scanned. Measure direction. In the second measurement method, the method of measuring the direction in which the object exists using the intermittent waveform signal as described above may be generally called a phase comparison monopulse method.

  The above is the description of the method for measuring the relative position and the relative speed with the object in the second measurement method. In this description, the case where the measurement range from the minimum measurement distance to the maximum measurement distance is divided into four range bins and scanned is described as an example. However, in the present embodiment, the number of range bins in the measurement range is not necessarily four, may be three or less, and may be five or more. When the number of range bins in the measurement range is increased, the length of the range bin is shortened, so that measurement with high distance resolution can be performed. However, when the number of range bins in the measurement range is increased, the number of scans in one cycle increases, so that the time required to scan all the range bins in the measurement range once increases. Therefore, the number of range bins and the width of the measurement range may be determined in advance according to the measurement period that the designer of the radar apparatus 1 according to the present embodiment considers preferable.

  Further, the interval Ph and the interval Bh described above may be freely determined in advance according to a measurement period determined by the designer of the radar apparatus 1 according to the present embodiment.

  Further, in the method of measuring the relative velocity in the second measurement method described above, it is proportional to the period from the first emission of electromagnetic waves to the second emission of electromagnetic waves, that is, the length of the emission interval Hk described above. As a result, the measurement accuracy of the speed changes. Therefore, the above-described radiation interval Hk in the second measurement method may be determined according to the required measurement accuracy of the relative velocity. However, in the second measurement method, if the radiation interval Hk is too long, the measurable maximum relative velocity range may be narrowed. Therefore, the radiation interval Hk in the second measurement method described above may be determined in advance in consideration of the required measurement accuracy of the relative velocity and the measurement range of the maximum relative velocity. As a specific example of the radiation interval Hk when the measurement accuracy of the relative speed and the measurement range of the maximum relative speed are respectively determined in advance, 10 μsec is cited. In the second measurement method, after measuring the relative speed a plurality of times, an average value of the measured relative speed may be calculated to obtain a more accurate relative speed.

  In the second measurement method described above, the measurement may be performed using an electromagnetic wave having a very short radiation time, that is, an UWB (Ultra Wide Band) electromagnetic wave, as the electromagnetic wave radiated from the radiating unit 104. Thereby, the shortest measurement distance of the relative distance which can be measured can be shortened, and distance resolution can be made fine. One of the definitions of UWB electromagnetic waves used in the present invention is that the specific bandwidth (bandwidth at which the signal level is 10 [dB] or higher / the center frequency of the bandwidth) is 20% or higher, or the bandwidth is An example of the definition of 500 [MHz] or higher is given. However, an electromagnetic wave defined as UWB by other definitions may be used.

  Further, LVDS (Low Voltage Differential Signaling) may be used as a method of generating an electromagnetic wave having a very short radiation time. Thereby, generally known common mode noise can be reduced.

  In the description of the second measurement method described above, whether or not a reflected wave has been received is determined by comparing a distributed signal and a signal obtained by mixing the received reflected wave with a predetermined threshold value. Was described as an example. According to this, the matched filter system that starts A / D conversion of the signal acquired by the control processing unit 109 when each of the time differences corresponding to the range bin to be operated (in the above description, the time difference td1 to the time difference td4) arrives. Can be used to determine whether or not a reflected wave has been received. Thereby, it is possible to perform measurement with good accuracy and SN ratio using an A / D converter with a relatively low sampling rate. Since an A / D converter having a relatively high sampling rate is generally high in cost, the radar device 1 according to the present embodiment can be manufactured at low cost by using a generally known matched filter method. It can be realized using an A / D converter.

  However, in the radar device 1 according to the present embodiment, a method that can be used to determine whether or not a reflected wave is received is not limited to the matched filter method, and is generally known as a high-speed method. An equivalent sampling method may be used. In addition, if possible, the reflected waves received by the first receiving unit 105a and the second receiving unit 105b are converted into a first wave using an A / D converter that can perform A / D conversion at a high sampling rate. The control processing unit 109 acquires the first signal through the first variable band limiting filter 108a to the fourth variable band limiting filter 108d, and directly A / D converts the acquired signal to obtain the rising edge of the A / D converted signal. It may be determined whether or not a reflected wave is received by detection.

  Further, in the method for determining whether or not a reflected wave is received by comparing the level of the directly A / D converted signal with a predetermined threshold value, the first variable band limiting filters 108a to 4th are used. The measurement accuracy of the relative distance may change depending on the width of the frequency band limited by the variable band limiting filter 108d. Therefore, in this case, the width of the frequency band limited by the first variable band limiting filter 108a to the fourth variable band limiting filter 108d in the second measurement method is determined according to the required relative distance measurement accuracy. Also good.

  In addition, the measurement method that can be used when measuring the direction in which the object is present in the first measurement method and the second measurement method described above is not limited to the method described above. As another method for measuring the direction in which the object exists, a generally known beam scanning method can be cited as an example. Thereby, when a plurality of objects are present at substantially the same relative distance, errors that occur in the measurement result in the direction in which the objects exist can be reduced.

  In the method of measuring the direction in which the object is present in the second measurement method, it occurs between the reflected wave Rf1 received by the first receiver 105a and the reflected wave Rf2 received by the second receiver 105b. The direction in which the object exists is measured based on the phase difference corresponding to the distance b, that is, the phase difference corresponding to the distance d between the first receiving unit 105a and the second receiving unit 105b. However, in the radar device 1 according to the present embodiment, a level generated according to the distance b between the reflected wave Rf1 received by the first receiver 105a and the reflected wave Rf2 received by the second receiver 105b. The direction in which the object exists may be measured based on the difference in level, that is, the level difference generated according to the distance d between the first receiving unit 105a and the second receiving unit 105b. This method may be generally called an amplitude comparison monopulse method.

  Furthermore, in the method of measuring the direction in which the object exists in the first measurement method and the second measurement method described above, two reception units (a plurality of reception units) of the first reception unit 105a and the second reception unit 105b are used. The case where measurement is performed based on the reflected wave received by the unit) has been described as an example. However, when measuring the direction in which the object is present in the radar apparatus 1 according to the present embodiment, a phased array method, a DBF (Digital Beam Forming) method, or the like is used using a plurality of three or more receiving units. The direction in which the object exists may be measured. Also, the phase comparison monopulse method or amplitude comparison monopulse method described above using a plurality of receiving units (in the first measurement method, a measurement method based on the level difference or phase difference of each reflected wave received by the plurality of receiving units. ) May be used.

  In the measurement by the first measurement method and the second measurement method, the relative distance to the object, the relative velocity, and the measurement in the direction in which the object exists may be measured in any order.

  The above is the description of the first measurement method and the second measurement method according to the present embodiment. Next, the control processing unit 109 according to the present embodiment measures the relative position and relative speed with the object using the first measurement method, and the vicinity of the object based on the measurement result according to the first measurement method. A method for determining the re-measurement range and measuring the determined re-measurement range using the second measurement method having a higher resolution than the first measurement method will be described.

  First, the operation of the control processing unit 109 for determining the remeasurement range described above will be described. FIG. 5 is a diagram illustrating, as an example, a case where the objects B and S exist within the measurement range in front of the vehicle Rs on which the radar device 1 is mounted. Further, in FIG. 5, it is assumed that the object B is approaching the vehicle Rs, that is, the sign of the relative speed between the object B and the vehicle Rs is negative. Further, in FIG. 5, it is assumed that the object S is moving away from the vehicle Rs, that is, the sign of the relative speed between the object S and the vehicle Rs is positive.

  FIG. 6 shows the reflection by either the first receiver 105a or the second receiver 105b when measuring the relative distance to the object by the first measurement method under the assumption shown in FIG. When a wave is received, the control processing unit 109 performs FFT processing on a signal obtained by performing IQ detection based on the signals generated by the first mixing unit 107a and the second mixing unit 107b, respectively. It is a figure which shows an example of the spectrum obtained by this. More specifically, FIG. 6A shows that when the reflected wave with respect to the electromagnetic wave having the first frequency fr1 is received, the control processing unit 109 performs FFT processing on the signal obtained by performing IQ detection. It is a figure which shows an example of the acquired spectrum. FIG. 6B is obtained when the control processing unit 109 performs FFT processing on a signal obtained by IQ detection when a reflected wave with respect to the electromagnetic wave having the second frequency fr2 is received. It is a figure which shows an example of a spectrum. The spectrum shown in FIG. 6 corresponds to the spectrum of the Doppler frequency of the signal received by the first receiving unit 105a or the second receiving unit 105b, respectively.

  FIG. 7 is a diagram for explaining a method in which the control processing unit 109 determines the remeasurement range Sh after measuring the relative distance to the object based on the spectrum signal shown in FIG. 6. The control processing unit 109 calculates and measures the relative distance to the object as described above based on the phase difference of the frequencies that cause the spectrum peaks shown in FIGS. 6 (a) and 6 (b). More specifically, the control processing unit 109 sets the phase difference between the phase of the signal with the frequency fa shown in FIG. 6A and the phase of the signal with the frequency fb shown in FIG. 6B as Δφ in Expression (6). By substituting, the relative distance to the object B shown in FIG. 7 is calculated. Similarly, the control processing unit 109 sets the phase difference between the phase of the signal with the frequency fa ′ shown in FIG. 6A and the phase of the signal with the frequency fb ′ shown in FIG. 6B as Δφ in Expression (6). By substituting, the relative distance to the object S shown in FIG. 7 is calculated. Here, in FIG. 7, the relative distance to the object B is defined as a relative distance Bk, and the relative distance from the object S is defined as a relative distance Sk.

  Then, when each of the relative distance Bk and the relative distance Sk is measured, the control processing unit 109 sets a remeasurement range Sh having a predetermined width centered on the measured relative distance, as shown in FIG. The above is the description of the operation for the control processing unit 109 to determine the remeasurement range described above. Note that when the actually determined remeasurement range Sh is measured by the second measurement method, only the range bins including all of the remeasurement ranges Sh are measured as shown in FIG. Further, the width of the remeasurement range Sh may be determined by multiplying the sum of the distance resolution of the relative distance and the measurement accuracy in the first measurement method by a positive constant. The constant may be a positive constant of any value, but as a specific example, it may be 1.2 or 2.0.

  Next, the processing of the control processing unit 109 will be described using the flowchart shown in FIG. In step S101, the control processing unit 109 performs measurement using the first measurement method, as described above, the reference signal generation unit 101, the modulation unit 102, the branching unit 103, and the first variable band limiting filters 108a to fourth. The variable band limiting filter 108d is instructed to prepare for the radar apparatus 1 to perform measurement by the first measurement method.

  In step S102, the control processing unit 109 starts measurement by the first measurement method, and measures the relative position and the relative speed with respect to the object.

  In step S103, the control processing unit 109 has detected whether or not the object has been detected in the measurement by the first measurement method, that is, has acquired a signal based on a reflected wave having a level exceeding a predetermined threshold value. Determine whether. When the control processing unit 109 determines in step S103 that the object has been detected, the control processing unit 109 proceeds to step S104. On the other hand, when the control processing unit 109 determines in step S103 that the object cannot be detected, the process returns to step S102.

  In step S104, the control processing unit 109 determines a remeasurement range by the method described above based on the acquired signal. In step S104, the control processing unit 109 may determine the remeasurement range based on the distance resolution of the relative distance and the measurement accuracy in the first measurement method as described above.

  In step S105, the control processing unit 109 performs measurement using the second measurement method, as described above, the reference signal generation unit 101, the modulation unit 102, the branching unit 103, and the first variable band limiting filters 108a to 108a. 4 is sent to the variable band limiting filter 108d to prepare the radar apparatus 1 for measurement by the second measurement method.

  In step S106, the control processing unit 109 measures the more accurate relative position and relative velocity with respect to the object using the second measurement method only for the remeasurement range determined in step S104.

  In step S107, the control processing unit 109 determines the relative position and relative speed measured in at least one of step S102 and step S106 as another ECU (Electric Control Unit) of the vehicle on which the radar apparatus 1 according to this embodiment is mounted. Etc. Note that the ECU or the like is based on the relative position and relative speed measured in at least one of step S102 and step S106, and the type of object measured (pedestrian, oncoming vehicle, preceding vehicle, etc.). May be analyzed.

  The above is the description of the radar device 1 according to the present embodiment. The radar apparatus 1 according to the present embodiment previously determines a remeasurement range in the vicinity of the object using the first measurement method, and compares only the determined remeasurement range using the second measurement method with high resolution. Measure distance. In the measurement by the second measurement method, measurement is performed with a relatively large number of range bins in order to measure the relative position and relative velocity with respect to the object with higher resolution than in the first measurement method. For this reason, if only the second measurement method is used and the entire measurement range is scanned with high resolution, the measurement time increases. However, in the radar apparatus 1 according to the present embodiment, the measurement range according to the second measurement method is determined by determining the remeasurement range in advance before performing the measurement with the second measurement method using the first measurement method. It can be predetermined. Thereby, the measurement range by the second measurement method is only in the vicinity of the object. Therefore, according to the radar apparatus 1 according to the present embodiment, the relative position and the relative speed of the object can be accurately measured in a short time while satisfying the performance required for the radar apparatus mounted on the vehicle. .

  In the description of FIGS. 5 to 7, the case where the remeasurement range is determined based on only the relative distance measured using the first measurement method has been described as an example. However, the radar apparatus 1 according to the present embodiment may determine the remeasurement range based on not only the relative distance but also the direction in which the object exists. In this case, as shown in FIG. 9, the control processing unit 109 measures the relative distance and the direction in which the object exists using the first measurement method, and centers the position determined by the measured relative distance and direction. A range of a predetermined size may be used as the remeasurement range.

  In the first measurement method and the second measurement method, the remeasurement range may be set using a beam former as a method of measuring the direction in which the object exists. The beam former scans from one end of the angle range to be measured to the other end, and a peak of the reflected wave level occurs at an angle corresponding to the direction in which the object exists. For this reason, when setting the re-measurement range, a range of a predetermined size centered on a position determined by the measured relative distance and the direction corresponding to the angle at which the peak of the level of the reflected wave occurs is the re-measurement range. It is good to do. In addition to the beam former, a MUSIC (MUltiple SIgnal Classification) method, an ESPRIT method, or the like may be used.

  Moreover, the measurement method of the direction in which the target object exists in the first measurement method and the second measurement method described above is a method for measuring the direction in which the target object on the horizontal plane exists in any method. However, in the radar apparatus 1 according to the present embodiment, the method and configuration for measuring the direction in which the object on the horizontal plane exists are applied to the measurement in the direction in which the object exists in the vertical plane orthogonal to the horizontal plane. Also good. In this case, by installing the first receiving unit 105a and the second receiving unit 105b in the vertical direction, it is possible to measure the direction in which the object on the vertical plane perpendicular to the horizontal plane exists. And even if the relative position and relative velocity of the object are measured three-dimensionally using the measurement method in the direction in which the object on the horizontal plane exists and the measurement method to measure the object on the vertical plane. Good. Furthermore, in the radar apparatus 1 according to the present embodiment, when the relative position and the relative speed of the object are measured three-dimensionally, as described with reference to FIGS. Good.

  In the description of the flowchart of FIG. 8 described above, only the measurement of the relative distance has been described. However, the radar device 1 according to the present embodiment, in the measurement by each of the first measurement method and the second measurement method, not only measures the relative distance but also measures the relative velocity and the direction in which the object exists. Needless to say, it may be parallel.

  Further, in the description of the flowchart of FIG. 8 described above, the case where the respective measurements by the first measurement method and the second measurement method are alternated is described as an example. However, the radar device 1 measures the relative speed of the object when the object is detected by the first measurement method, the measured relative speed is greater than a predetermined threshold value, and the object is a radar. When it is determined that the device 1 is approaching, the vicinity of the object may be immediately measured again by the second measurement method, and the relative position and the relative speed may be measured.

(Modification of the first embodiment)
The levels of the electromagnetic waves radiated from the radiating unit 104 and the reflected waves received by the first receiving unit 105a and the second receiving unit 105b are attenuated according to the distance by propagating through the space. This attenuation amount increases in proportion to the length of the propagation distance. For this reason, the maximum measurement range of the radar apparatus may be narrowed. Therefore, in the radar device according to the modification of the first embodiment, the level of the signal based on the reflected wave acquired by the control processing unit 109 is increased by integrating the level of the signal based on the received reflected wave. Thereby, the maximum measurement range can be widened. Hereinafter, a radar device according to a modification of the first embodiment will be described in detail.

  FIG. 10 is a block diagram showing a schematic configuration of the radar apparatus 2 according to a modification of the first embodiment of the present invention. The radar device 2 is different from the radar device 1 according to the first embodiment in that the radar device 2 further includes a first integration unit 110a to a fourth integration unit 110d. Therefore, in the radar device 2, the same components as those of the radar device 1 according to the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The first integrating unit 110a to the fourth integrating unit 110d are respectively the first variable band limiting filter 108a to the fourth variable band limiting filter 108d only when performing the measurement in the second measurement method described above. The signals that passed through are integrated a predetermined number of times. That is, the first integration unit 110a to the fourth integration unit 110d perform the measurement in the first measurement method described above, and the first variable band limiting filter 108a to the fourth variable band limiting filter 108d. Are directly transmitted to the control processing unit 109 without being integrated.

  When the first integration unit 110a to the fourth integration unit 110d perform measurement by the second measurement method, the same range bin is scanned a predetermined number of times in accordance with an instruction from the control processing unit 109. It is repeated for all the range bins, and the level of the reflected wave received for the same number of times is integrated. Each time the control processing unit 109 repeats scanning the same range bin a predetermined number of times, the control processing unit 109 outputs a signal based on the reflected wave whose level is integrated by the first integration unit 110a to the fourth integration unit 110d. Obtain and perform the arithmetic processing described above. That is, the radar apparatus 2 increases the level of the reflected wave corresponding to one range bin by receiving the reflected wave corresponding to one range bin a predetermined number of times and integrating the level. Thereby, the radar apparatus 2 can raise the level of the reflected wave corresponding to a relatively long range bin, and widens the maximum measurement range as compared with the radar apparatus 1 according to the first embodiment. Can do.

  However, increasing the number of integrations may increase the measurement time for scanning the entire measurement range once because the number of scans for one range bin increases. Therefore, in the radar apparatus 2 according to the modified example of the first embodiment, the control processing unit 109 includes the first accumulation unit 110a to the fourth accumulation unit 110d according to the range bin to be scanned, that is, the measurement distance to be scanned. The number of integrations may be changed.

  More specifically, in the modified example of the first embodiment, the number of times of reflection wave level integration corresponding to the range bin at a distance relatively close to the radar device 2 is decreased, and the range bin at a relatively far distance is used. The number of times of integration of the reflected wave level corresponding to may be increased. This is because the reflected wave corresponding to the range bin at a relatively close distance has a short propagation distance, so the level attenuation is considered to be relatively low, and the reflected wave corresponding to the range bin at a relatively far distance has a propagation distance of This is because the attenuation amount of the level is considered to be relatively high because it is long.

  FIG. 11 is a diagram illustrating an example of the number of integrations that the control processing unit 109 changes based on the correspondence between the level of the reflected wave received by the radar device 2 and the measurement distance. In the modification of the first embodiment, as shown in FIG. 11, the number of integrations determined by experiments or the like may be used, or the number of integrations theoretically determined based on a radar equation or the like may be used.

  Note that the radar apparatus 2 according to the modification of the first embodiment may cause an increase in measurement time in the second measurement method as described above. However, also in the radar device 2 according to the modification of the first embodiment, as shown in the flowchart of FIG. 7, if only the remeasurement range is measured by the second measurement method, the increase in the number of integrations becomes the measurement time. The impact can be minimized.

  The above is the description of the radar device according to the present invention. As shown in FIG. 12, one or more radar devices according to the present invention may be mounted on the vehicle according to the direction or distance included in the measurement range. In the radar apparatus according to the present invention, as shown in FIG. 13, the center axis of the radar and the range in which the direction in which the object exists is measured, that is, the center axis of the angle measurement range does not necessarily match. Also good.

  In the second measurement method, the case where a signal having a phase is radiated as an electromagnetic wave has been described as an example. However, the radar apparatus according to the present invention may perform measurement by radiating an impulse signal having no phase as an electromagnetic wave when performing measurement in the second measurement method. At this time, since the reflected wave also has no phase, the relative velocity with the object cannot be measured by the method for measuring the relative velocity with the object in the second measurement method described above. Therefore, when the radar apparatus according to the present invention performs measurement by emitting an impulse signal in the second measurement method, the relative velocity with respect to the object can be obtained by differentiating the measured relative distance with respect to time. Good.

  However, in the method of measuring the relative speed by differentiating the relative distance with time, the relative speed measurement accuracy may be relatively poor. For this reason, when the measurement is performed by emitting an impulse signal in the second measurement method, the relative velocity with the object measured in advance by the first measurement method and the object measured by the second measurement method are calculated. It may be determined whether or not the difference from the relative speed is within a predetermined range. Then, when the relative speed with the object measured by the second measurement method is within a predetermined range, the relative speed of the object measured by the second measurement method is measured by the first measurement method. Alternatively, the relative velocity of the target object may be used.

  Further, in the first embodiment and the modification of the first embodiment described above, an example is a case where measurement is not started by the second measurement method until an object is detected by measurement by the first measurement method. As explained. However, in the measurement by the first measurement method described above, the phase cannot be detected depending on the relative distance to the object, and it may be difficult to measure the object. For this reason, the radar apparatus according to the present invention can measure a relatively close distance regardless of whether the object can be detected by the measurement by the first measurement method, that is, the measurement result by the first measurement method. Regardless, the measurement by the second measurement method may be performed. When the radar apparatus according to the present invention is mounted on a vehicle, an emphasis may be placed on measurement of a pedestrian, a child, a cart, or the like that is present at a relatively close distance or a blind spot of a passenger. Regardless of the measurement result of the first measurement method, the measurement by the second measurement method can reliably measure pedestrians, children, carts, etc. that are present at a relatively close distance or the blind spot of the passenger. be able to. As an example of the range of the relatively close distance at this time, 0.1-5 [m] is mentioned.

  In the first measurement method described above, a case where measurement is performed with a wide maximum measurement range using a signal having a narrow frequency band in which the frequency difference between the frequency fr1, the frequency fr2, and the frequency fr3 is relatively narrow has been described as an example. . However, when measurement is performed using such a narrow-band signal, the distance resolution is deteriorated and the minimum measurement range is increased, so that it is difficult to measure an object at a relatively short distance. Therefore, in the radar apparatus according to the present invention, the measurement range that is difficult to measure by the first measurement method may be measured by the second measurement method regardless of the measurement result by the first measurement method. Thereby, it is possible to reliably measure a measurement range that is difficult to measure with the first measurement method.

  Further, in the first measurement method and the second measurement method described above, the case where the relative distance and the relative speed with the object are measured by different measurement methods has been described as an example. Therefore, in the first measurement method and the second measurement method, the frequency bands of the radiated electromagnetic wave carriers may be different from each other. FIG. 14 shows a more specific example of combinations of frequency bands of respective carriers in the first measurement method and the second measurement method. The ISM in FIG. 14 indicates a frequency band determined by the International Telecommunications Union (ITU) within the same frequency band.

  Moreover, the following can be said about the frequency band of the electromagnetic waves used in the first measurement method and the second measurement method in the present invention. In the first measurement method, as an example, measurement is performed using an electromagnetic wave in a relatively narrow frequency band around the carrier frequency by reducing the frequency difference between the electromagnetic waves as described above. On the other hand, in the second measurement method, as an example, measurement is performed by using an electromagnetic wave having a short pulse width as described above. An electromagnetic wave having a short pulse width generally has a wide frequency band. That is, in the present invention, as an example, the first measurement method uses a narrowband signal with a relatively narrow frequency band, and the second measurement method uses a wideband signal with a relatively wide frequency band. Measure. Thereby, the radar apparatus according to the present invention can complete the measurement in a short time while satisfying the performance required for the radar apparatus mounted on the vehicle, as described above.

  Further, it goes without saying that the embodiment described in the present invention and its modifications may be combined in any way.

  In the above description, the radar device according to the present invention has been described as an example when mounted on a vehicle. However, the radar apparatus according to the present invention may be mounted not only on the vehicle but also on any moving body including the vehicle.

  In the first embodiment described above, the description has been made on the assumption that the first variable band limiting filter 108a to the fourth variable band limiting filter 108d each process an analog signal. However, the first variable band limiting filter 108a to the fourth variable band limiting filter 108d may each process a digital signal. When a digital filter is used as each of the first variable band limiting filter 108a to the fourth variable band limiting filter 108d, the first variable band limiting filter 108a to the fourth variable band limiting filter are not used inside the control processing unit 109. It is preferable to provide an A / D converter before each stage 108d.

  Further, an A / D converter may be provided inside the control processing unit 109 so that the functions of the first variable band limiting filter 108a to the fourth variable band limiting filter 108d that handle digital signals are integrated into the control processing unit 109. Good. Thereby, the radar apparatus 1 can be saved in space. Also, the first integration unit 110a to the fourth integration unit 110d in the modification of the first embodiment process digital signals in the same manner as the first variable band limiting filter 108a to the fourth variable band limiting filter 108d. Needless to say, the functions of the first integration unit 110a to the fourth integration unit 110d that handle digital signals may be integrated into the control processing unit 109.

  Further, in the first embodiment and the modification of the first embodiment described above, as shown in FIGS. 1 and 10, a mixing unit is provided for each of the first receiving unit 105 a and the second receiving unit 105 b. A configuration in which two are provided has been described as an example. However, in the present embodiment, as illustrated in FIG. 15, the switching unit 111 may be configured to switch a path connecting either one of the first receiving unit 105 a and the second receiving unit 105 b and a circuit in the subsequent stage. . In the radar apparatus having the configuration shown in FIG. 15, when measuring the direction in which the object exists by the first measurement method, the switching unit is at least once in the period in which the electromagnetic wave of one frequency is radiated as described above. The path is switched by 111, and the phase or amplitude of the signals received by the two receiving units may be compared. In the radar apparatus having the configuration shown in FIG. 15, when measuring the direction in which the object is present by the second measurement method, the control processing unit 109 is at least 2 for one range bin with respect to the radiation unit 104. When the timing of receiving the reflected wave of the electromagnetic wave radiated for the first time has passed while the electromagnetic wave is radiated once, the switching unit 111 is instructed to switch the path, and the reflection of the electromagnetic wave radiated the second time Good to receive waves. Then, similarly to the above-described method, the control processing unit 109 compares the phase or amplitude of the reflected wave with respect to the electromagnetic wave radiated first time and the reflected wave with respect to the electromagnetic wave radiated second time, thereby comparing the target object. The existing direction may be measured.

  In the first embodiment and the modification of the first embodiment described above, the remeasurement range is set based on the measurement result by the first measurement method, and the set remeasurement range is determined by the second measurement method. The case where measurement is performed, that is, the case where measurement is performed by alternately using the first measurement method and the second measurement method has been described as an example. As described above, when the measurement by the first measurement method and the second measurement method are alternately repeated, the time required for measuring the relative position and the relative velocity by the first measurement method and setting the remeasurement range. Is relatively long, and when the relative position and relative velocity are measured by the first measurement method and the process until the re-measurement range is set, the measurement is started by the second measurement method. There may be a case where the timing is not met. In this case, in order to determine the re-measurement range for measurement by the second measurement method, for example, the measurement result of the relative position and the relative velocity obtained by the measurement by the first measurement method two times before is used. May be. As a result, even if the relative position and relative velocity measurement by the first measurement method does not meet the timing for starting the setting of the remeasurement range for the next measurement by the second measurement method, It is possible to set a re-measurement range for measuring with the two measurement methods. In this case, when the measurement is first performed by the second measurement method, that is, when the measurement result by the first measurement method is not obtained, for example, a predetermined initial remeasurement range is set to the second measurement method. It is good also as what measures by a system.

  Moreover, in the description of each of the first measurement method and the second measurement method described above, as a method for detecting the phase of the reflected wave, a case where IQ detection and FFT processing are performed based on a set of two signals is taken as an example. explained. However, in the present embodiment, when detecting the phase of the reflected wave, it is not always necessary to detect the phase based on the set of two signals, and any one of the four signals acquired by the control processing unit 109 is selected. The phase may be detected by performing FFT processing on the signal. Accordingly, a configuration for IQ detection, that is, a radar apparatus according to the present invention can be provided at a low cost by omitting the 90-degree phase shift unit 106, the second mixing unit 107b, and the fourth mixing unit 107d. Can do. However, when the phase of the reflected wave is detected based on any one signal in this way, it is difficult to determine the sign of the relative velocity. That is, it becomes difficult to determine whether the object is approaching or moving away from the radar device according to the present invention. Therefore, when the configuration for detecting the phase based on one signal as described above is employed, the relative velocity may be measured by differentiating the measured relative distance with respect to time.

  Moreover, it is needless to say that the above description of the first embodiment and the modified example of the first embodiment is an example, and various improvements may be made without departing from the gist of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the relative position and relative speed of a target object can be measured accurately in a short time, for example, it can utilize for the radar apparatus etc. which are mounted in a vehicle.

1 is a block diagram showing a schematic configuration of a radar apparatus according to a first embodiment. The figure explaining the electromagnetic waves radiated | emitted in a 1st measurement system The figure explaining the method to measure the direction in which a target object exists in a 1st measurement system The figure explaining the measuring method in a 2nd measuring system Diagram showing the positional relationship of objects Diagram showing reflected wave spectrum Diagram explaining how to determine the remeasurement range The flowchart explaining the process of the control process part which concerns on 1st Embodiment. Diagram explaining how to determine the remeasurement range The block diagram which shows schematic structure of the radar apparatus which concerns on the modification of 1st Embodiment. The figure which shows an example of the method of determining the number of integration The figure which shows the position in the vehicle of the radar apparatus which concerns on this invention Diagram explaining the central axis of the radar device and the central axis of the angle measurement range Diagram explaining combinations of carrier wave frequencies The figure which shows an example of how to connect a receiving part

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radar apparatus 2 Radar apparatus 101 Reference signal generation part 102 Modulation part 103 Branch part 104 Radiation part 105a 1st receiving part 105b 2nd receiving part 106 90 degree | times phase shift part 107a 1st mixing part 107b 2nd mixing part 107c third mixing unit 107d fourth mixing unit 108a first variable band limiting filter 108b second variable band limiting filter 108c third variable band limiting filter 108d fourth variable band limiting filter 109 control processing unit 110a first 1 integration unit 110b second integration unit 110c third integration unit 110d fourth integration unit 111 switching unit

Claims (16)

A radar device that measures a relative position and a relative velocity with respect to an object based on an electromagnetic wave radiated by a radiating means and a reflected wave received by a receiving means,
Based on the electromagnetic wave radiated by the radiating means and the reflected wave received by the receiving means, the relative position and the relative velocity with respect to the object are respectively measured by the first measurement method in a predetermined measurement range. First measuring means;
When the relative position is measured by the first measuring means, based on the electromagnetic wave radiated by the radiating means and the reflected wave received by the receiving means , the relative position is the center, and from the measurement range A second measuring means for measuring a relative position and a relative velocity with respect to the object with a higher resolution than the first measuring means by a second measuring method in a narrow remeasurement range,
When the second measuring means determines that the object whose relative position is measured by the first measuring means is approaching at a relative speed faster than a predetermined relative speed, A radar device that immediately measures the relative position and speed of the. Filtering means for limiting the passing frequency band of the reflected wave;
When the first measuring means performs measurement, the passing frequency band of the filtering means is set to a predetermined narrow band, and when the second measuring means performs measurement, the passing frequency band of the filtering means is set. Setting means for setting a predetermined wide band; and
Each of the first measuring means and the second measuring means is based on the electromagnetic wave and the reflected wave whose frequency band is limited to the passing frequency band set by the setting means. The radar device according to claim 1 which measures a position. The second measuring means includes
Accumulating means for integrating the level of the reflected wave whose pass frequency band is limited by the filtering means every time the reflected wave is received;
An integration number setting means for setting the integration number of the integration means according to the relative position measured by the first measurement means,
The radar apparatus according to claim 2, wherein the second measurement unit measures a relative position with respect to the object based on the electromagnetic wave and the reflected wave whose level is accumulated by the accumulation unit.   The radar device according to any one of claims 1 to 3, wherein the first measuring unit measures a relative distance and a relative velocity with respect to the object using an FM-CW method.   The radar device according to any one of claims 1 to 3, wherein the first measuring unit measures a relative distance and a relative velocity with respect to the object using an FSK method. The receiving means includes a plurality of antennas for receiving the reflected waves,
6. The radar according to claim 4, wherein the first measuring unit measures a direction of a relative position of the object based on a plurality of the reflected waves respectively received by a plurality of antennas. apparatus.   The radar apparatus according to claim 6, wherein the first measurement unit measures the direction of the relative position of the object based on the phases of the plurality of reflected waves respectively received by a plurality of antennas.   The radar apparatus according to claim 6, wherein the first measuring unit measures a direction of a relative position of the object based on a plurality of levels of the reflected waves respectively received by a plurality of antennas.   The radar apparatus according to claim 1, wherein the second measuring unit measures a relative distance from the object using a pulse Doppler method.   The radar apparatus according to any one of claims 1 to 8, wherein the second measuring unit measures a relative distance from the object using a PSK method. The receiving means includes a plurality of antennas for receiving the reflected waves,
The said 2nd measurement means measures the direction of the relative position with the said target object based on the said several reflected wave each received by the some antenna, The any one of Claims 9 thru | or 10 Radar device.   The second measuring means measures a direction of a relative position with respect to the object using a phase comparison monopulse method based on phases of the plurality of reflected waves respectively received by a plurality of antennas. The radar device described in 1.   The second measuring means measures the direction of the relative position with respect to the object using an amplitude comparison monopulse method based on the levels of the plurality of reflected waves respectively received by a plurality of antennas. The radar device described in 1.   The radar device according to any one of claims 1 to 13, which is mounted on a moving body.   The radar device according to claim 14, which is mounted on a vehicle.   The second measuring means includes in advance a relative position already obtained by the measurement by the first measuring means performed in the past rather than the measurement of the relative position by the first measuring means performed most recently. The radar according to any one of claims 1 to 15, wherein only a predetermined measurement range is scanned, and a relative position and a relative velocity with respect to the object are measured with higher resolution than the first measurement unit. apparatus.

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