JP2020003357A - Radar device and target detection method - Google Patents

Abstract

To provide a technique with which it is possible to improve the accuracy of detecting a distance reflection ghost.SOLUTION: In a radar device 100, a signal generation unit 11 generates a fundamental transmit signal TS1. A phase change unit 12 generates a phase change transmit signal TS2. A transmit unit 20 outputs the fundamental transmit signal TS1 and the phase change transmit signal TS2 as transmit waves. A ghost detection unit 44 specifies two peaks of the same target from a two-dimensional power spectrum PS at a first time of day, and selects a peak having a minimum speed from within the two specified peaks. The ghost detection unit 44 estimates a position of the selected peak in the two-dimensional power spectrum PS at a second time of day. The ghost detection unit 44 determines whether or not the two-dimensional power spectrum PS at the second time of day includes a peak that corresponds to the estimated position of the selected peak.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a radar device for detecting a target and a target detection method used in the radar device.

  As a radar device for detecting a target, a radar device of the FCM (Fast Chirp Modulation) method is known. The FCM radar device generates a transmission signal including a plurality of continuous chirp signals, and outputs the generated transmission signal as a transmission wave. The FCM type radar device receives a reflected wave of a transmitted wave reflected by a target. The FCM radar device generates a beat signal from a transmission signal and a reception signal acquired from a received reflected wave, and performs a fast Fourier transform on the generated beat signal to generate a two-dimensional spectrum.

  The FCM radar device obtains the distance of the target based on the frequency of the beat signal, and obtains the speed of the target based on the phase change of the beat signal. Since the FCM radar device can determine the distance to the target and the speed of the target separately, it is expected that more accurate target detection will be possible.

  For example, Patent Document 1 discloses an FCM type radar device mounted on a vehicle such as an automobile.

JP-A-2006-3873

  The FCM radar device detects the distance of a target based on the position of a peak appearing in a two-dimensional spectrum. However, a phenomenon called distance folding may occur in the two-dimensional spectrum. The distance wrapping means that a peak corresponding to this target appears at a distance shorter than the maximum detection distance, even though the target is located farther than the maximum detection distance of the FCM radar apparatus. If the peak corresponding to the target appears at a distance closer than the maximum detection distance even though the target is located farther than the maximum detection distance, the peak is called a distance-turning ghost.

  In the FCM type radar device, the maximum detection distance depends on the sampling frequency. By increasing the sampling frequency, the maximum detection distance can be increased. In other words, by increasing the sampling frequency and setting the maximum detection distance to a sufficiently long distance, it is possible to prevent the occurrence of distance-turning ghost.

  Due to the limitations of the hardware used in the FCM type radar device, the sampling frequency cannot be increased without limit. Distance wrapping occurs when a peak indicating a frequency exceeding the Nyquist frequency wraps around the Nyquist frequency as the axis of symmetry. Therefore, it is difficult to completely prevent the occurrence of distance aliasing due to the sampling frequency in the FCM type radar device. However, in the FCM type radar apparatus, it is necessary to improve the detection accuracy of the distance return ghost.

  An object of the present invention is to provide a technique that can improve the detection accuracy of a distance-turning ghost.

  In order to solve the above problems, a first invention is a radar device. The radar device includes a signal generation unit, a phase change unit, a transmission unit, a conversion unit, and a ghost detection unit. The signal generation unit generates a basic transmission signal. The phase change unit applies a periodic phase change to the basic transmission signal to generate a phase change transmission signal. The transmitting section outputs the basic transmission signal and the phase-change transmission signal as transmission waves. The conversion unit generates a spectrum including a distance axis corresponding to the distance of the target and a speed axis corresponding to the speed of the target from the basic transmission signal and the reception signal acquired by the reception unit. The ghost detection unit determines whether the peak included in the spectrum is a distance-turning ghost. The ghost detection unit includes a group generation unit, a peak selection unit, a position estimation unit, and a determination unit. The group generation unit specifies a plurality of peaks having the same distance from the spectrum at the first time, and a case where intervals in the speed axis direction in the plurality of specified peaks correspond to a speed difference derived from a periodic phase change. And a detection group including a plurality of specified peaks. The peak selection unit selects a peak that satisfies a selection condition determined based on a periodic phase change among a plurality of peaks included in the detection group. The position estimating unit estimates the position of the selected peak in a spectrum at a second time different from the first time based on the position of the selected peak selected by the peak selecting unit. When the spectrum at the second time does not include a peak corresponding to the estimated position of the selected peak, the determination unit determines that the peak included in the detection group is a distance-turning ghost.

  According to the first aspect, by giving a periodic phase change to the basic transmission signal TS1, two peaks indicating the same target are formed in the spectrum at the first time. One of the two peaks is a real image peak indicating the relative speed with respect to the radar device, and the other is a virtual image peak including the relative speed and an apparent Doppler speed due to a periodic phase change. When the distance aliasing occurs, the magnitude relationship between the speed of the real image peak and the speed of the virtual image peak is switched. The first invention detects a distance-turning ghost by utilizing the above-mentioned exchange of the magnitude relation between the speeds. Therefore, it is possible to improve the detection accuracy of the distance return ghost.

  A second invention is the first invention, wherein the position estimating unit calculates a moving distance of the selected peak in a period from the first time to the second time based on the speed of the selected peak, and estimates the selected peak. The position is estimated based on the calculated moving distance.

  According to the present invention, it is possible to improve the accuracy of the estimated position of the selected peak in the spectrum at the second time. Therefore, it is possible to further improve the detection accuracy of the distance return ghost.

  A third invention is the first invention, wherein the basic transmission signal includes a plurality of chirp signals. When the phase changing unit increases the phase of each of the plurality of chirp signals, the peak selecting unit selects the peak having the lowest speed among the plurality of peaks included in the detection group.

  According to the third aspect, when a distance aliasing ghost occurs, the virtual image peak is selected as the selected peak, so that the distance aliasing ghost can be detected.

  The fourth invention is any one of the first to third inventions, wherein the determination unit does not have a peak at a second time point within a predetermined range based on an estimated position of the selected peak. , It is determined that the selected peak is a distance-turning ghost.

  According to the fourth aspect, even when the peak corresponding to the selected peak does not completely match the estimated position, it can be determined that the selected peak is not a distance-turning ghost.

  A fifth invention is any one of the first to fourth inventions, wherein the transmission unit includes a first transmission antenna and a second transmission antenna. The first transmitting antenna outputs a basic transmission signal as a basic transmission wave. The second transmitting antenna outputs the phase-change transmission signal as a phase-change transmission wave.

  According to the fifth aspect, since it is not necessary to combine the basic transmission signal and the phase-change transmission signal, the configuration of the radar device can be simplified.

  In a sixth aspect based on any one of the first to fourth aspects, the phase change unit combines the fundamental transmission signal and the phase-changed transmission signal to generate a combined transmission signal. The transmitting unit includes a transmitting antenna. The transmission antenna outputs the combined transmission signal generated by the phase change unit as a transmission wave.

  According to the sixth aspect, the transmission signal generated by the signal generation unit and the transmission signal to which a periodic phase change is given do not have to be supplied to separate transmission antennas. Therefore, the number of transmission antennas included in the radar device can be reduced.

  A seventh invention is the sixth invention, wherein the basic transmission signal includes a plurality of chirp signals. The phase change unit adds a phase change amount set for each of the plurality of chirp signals to each of the plurality of chirp signals, thereby giving a periodic change to the transmission signal generated by the signal generation unit, and performing combined transmission. The amplitude of the chirp signal included in the signal is changed based on the amount of phase change.

  According to the seventh aspect, the power of the real image peak and the virtual image peak can be suppressed from varying with time. The real image peak is derived from a reflected wave of a transmission wave based on the transmission signal generated by the signal generation unit and reflected by the target. The virtual image peak is derived from a reflected wave of a transmission wave based on a transmission signal to which a periodic phase change is given, which is reflected by a target. Since the temporal fluctuation of the power of the real image peak and the virtual image peak is suppressed, it is possible to prevent the real image peak and the virtual image peak from being instantaneously detected from the spectrum. Therefore, it is possible to stably judge whether or not a distance-turning ghost has occurred over time.

  The eighth invention is a target detecting method, wherein a) step, b) step, c) step, d) step, e) step, f) step, g) step, and h) step. And i) a step. a) generating a basic transmission signal; b) applying a periodic phase change to the basic transmission signal to generate a phase-change transmission signal. The step c) outputs the basic transmission signal and the phase-change transmission signal as transmission waves. The step d) generates a spectrum including a distance axis corresponding to the distance of the target and a speed axis corresponding to the speed of the target by using the basic transmission signal and the reception signal acquired by the receiving antenna. In step e), it is determined whether or not the peak included in the spectrum is a distance-turning ghost. f) the step of identifying a plurality of peaks having the same distance from the spectrum at the first time, wherein the intervals in the velocity axis direction at the identified plurality of peaks correspond to a velocity difference derived from a periodic phase change; And generating a detection group including a plurality of specified peaks. g) selecting a selected peak that satisfies a selection condition determined based on a periodic phase change among a plurality of peaks included in the detection group. h) estimating the position of the selected peak in the spectrum at the second time different from the first time based on the position of the selected peak. i) In the step, when the spectrum at the second time does not include a peak corresponding to the estimated position of the selected peak, it is determined that the peak included in the detection group is a distance-turning ghost.

  The eighth invention is used in the first invention.

  ADVANTAGE OF THE INVENTION This invention can improve the detection accuracy of a distance return ghost.

FIG. 3 is a diagram illustrating an example of a positional relationship between the radar device and a target according to the first embodiment of the present invention. FIG. 2 is a diagram illustrating an outline of operation of the radar device illustrated in FIG. 1. FIG. 2 is a functional block diagram illustrating a configuration of the radar device illustrated in FIG. 1. FIG. 2 is a functional block diagram illustrating a configuration of a ghost detection unit illustrated in FIG. 1. 2 is a flowchart of a transmission process executed by the radar device shown in FIG. FIG. 2 is a diagram illustrating an example of a pattern table illustrated in FIG. 1. FIG. 2 is a diagram illustrating a phase change of a chirp signal included in the basic transmission signal illustrated in FIG. 1. 3 is a flowchart of target data generation processing executed by the processing unit shown in FIG. 1. FIG. 2 is a diagram illustrating an example of peak data generated by a preprocessing unit illustrated in FIG. 1. FIG. 2 is a diagram illustrating an example of a positional relationship between two peaks in a spectrum generated by the conversion unit illustrated in FIG. 1. FIG. 2 is a diagram illustrating another example of a positional relationship between two peaks in a spectrum generated by the conversion unit illustrated in FIG. 1. FIG. 2 is a diagram illustrating an example of a correspondence relationship between peaks in two spectra generated by the conversion unit illustrated in FIG. 1. FIG. 2 is a diagram illustrating another example of the correspondence between peaks in two spectra generated by the conversion unit illustrated in FIG. 1. 9 is a flowchart of a ghost detection process shown in FIG. It is a functional block diagram showing the composition of the radar device concerning a 2nd embodiment of the present invention. FIG. 16 is a diagram illustrating an example of a pattern table illustrated in FIG. 15. FIG. 16 is a diagram illustrating an example of a positional relationship between three peaks in a spectrum generated by the radar device illustrated in FIG. 15. It is a functional block diagram showing the composition of the radar device concerning a 3rd embodiment of the present invention. FIG. 19 illustrates an example of a pattern table illustrated in FIG. 18. FIG. 19 is a diagram showing a basic pattern used for generating the pattern table shown in FIG. 18. 21 is a diagram illustrating an example of the combination of the basic patterns illustrated in FIG. 20. FIG. FIG. 2 is a diagram illustrating a CPU bus configuration.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

[First Embodiment]
{1. Positional relationship between radar device 100 and target 物
FIG. 1 is a diagram illustrating an example of a positional relationship between a target and the radar device 100 according to the present embodiment. Referring to FIG. 1, radar apparatus 100 is a FCM (Fast Chirp Modulation) type radar apparatus, and is installed on the front end surface of vehicle 1A. In this embodiment, the vehicle 1A is an automobile, and runs on a one-way, one-way, two-way road. The vehicle 2A is located in front of the vehicle 1A and is traveling in the same lane as the vehicle 1A travels. Vehicle 2A is the target in the present embodiment.

  The front of the vehicle 1A is the direction in which the vehicle 1A travels straight, that is, the direction from the driver's seat to the steering. Behind the vehicle 1A is the direction in which the vehicle 1A travels straight, that is, the direction from the steering to the driver's seat. The front and rear of the vehicle 2A are defined similarly to the vehicle 1A.

  In the present embodiment, the front of the vehicle 1A is defined as a positive direction, and the rear of the vehicle 1A is defined as a negative direction.

  Radar device 100 transmits transmission wave TW to the front of vehicle 1A. The transmission wave TW includes a basic transmission wave TW1 and a phase-change transmission wave TW2. Details of the basic transmission wave TW1 and the phase-change transmission wave TW2 will be described later.

  The radar device 100 receives the reception wave RW and detects the target vehicle 2A. The received wave RW includes a fundamental reflected wave RF1 and a phase-change reflected wave RF2. The basic reflected wave RF1 is the basic transmission wave TW1 reflected on the rear end face of the vehicle 2A. The phase-change reflected wave RF2 is a phase-change transmission wave TW2 reflected on the rear end face of the vehicle 2A.

{2. Outline of operation of radar device 100
Referring to FIG. 1, radar apparatus 100 generates basic transmission signal TS1 including a plurality of continuous chirp signals. The radar device 100 generates a phase change transmission signal TS2 by giving a periodic phase change to the generated basic transmission signal TS1. The radar apparatus 100 transmits the generated basic transmission signal TS1 as the basic transmission wave TW1, and transmits the generated phase change transmission signal TS2 as the phase change transmission wave TW2.

  The radar device 100 acquires a received signal from the received wave RW, and mixes the acquired received signal with the basic transmission signal TS1 to generate a beat signal. The radar apparatus 100 performs a fast Fourier transform on the generated beat signal to generate a two-dimensional spectrum. The radar apparatus 100 determines whether or not the peak included in the two-dimensional spectrum is a distance-turning ghost.

  FIG. 2 is a diagram for explaining the principle of detecting a distance turning ghost by the radar apparatus 100 shown in FIG. FIG. 2 shows a coordinate space represented by the distance axis and the velocity axis of the two-dimensional spectrum PS generated by the radar device 100. The distance axis is a frequency axis corresponding to the distance from the radar device 100 to the target. The speed axis is a frequency axis corresponding to a relative speed based on the radar device 100.

Referring to FIG. 2, 2-dimensional spectrum PS is generated on the basis of the transmitted wave TW, which is sent at time T _k. Time _{T k} is the transmission time of the transmitted wave TW. The two-dimensional spectrum PS includes peaks Pa and Pb. Peaks Pa and Pb are distance-turned ghosts. One of the peaks Pa and Pb is a peak based on the fundamental reflected wave RF1, and the other is a peak based on the phase-change reflected wave RF2. That is, the peaks Pa and Pb indicate the same target (vehicle 2A).

  The true peaks Pa 'and Pb' indicate the true positions of the peaks Pa and Pb. The peak Pa has a point-symmetric relationship with the true peak Pa 'with respect to the intersection CR between the speed axis and the straight line ML. The peak Pb has a point-symmetric relationship with the true peak Pb 'with respect to the intersection CR. The straight line ML indicates the detection distance of the radar device 100 determined by the Nyquist frequency in the distance axis direction.

  When the peaks Pa and Pb have the same distance Dk and the speed difference ΔV1 between the peak Pa and the peak Pb corresponds to a speed difference derived from a periodic phase change, the radar device 100 sets the peaks Pa and Pb Are determined to indicate the same target. The radar device 100 generates a detection group G including the peaks Pa and Pb.

The radar device 100 selects the peak Pb having the minimum speed in the detection group G. The radar apparatus 100 estimates the position ES at which the peak corresponding to the selected peak Pb appears in the two-dimensional spectrum PS at the time _Tk-1 . Time T _k-1 is the transmission time of the set transmission wave TW immediately before the time T _k. In FIG. 2, the length from the estimated position ES to the peak Pb is exaggerated.

When the two-dimensional spectrum at the time _Tk-1 does not include a peak corresponding to the estimated position ES, the radar device 100 determines that the peaks Pa and Pb forming the detection group G are distance-turning ghosts.

{3. Configuration of radar device 100
{3.1. overall structure}
FIG. 3 is a functional block diagram showing the configuration of the radar device 100 shown in FIG. Referring to FIG. 3, radar device 100 includes supply unit 10, transmission unit 20, reception unit 30, and processing unit 40.

  The supply unit 10 generates a basic transmission signal TS1 and a phase change transmission signal TS2 and supplies the generated transmission signal TS2 to the transmission unit 20. The supply unit 10 supplies the generated basic transmission signal TS1 to the reception unit 30.

  The transmission unit 20 transmits the basic transmission signal TS1 and the phase change transmission signal TS2 received from the supply unit 10 as a transmission wave TW.

  The receiving unit 30 receives the reception wave RW, acquires the reception signal RS, and receives the basic transmission signal TS1 from the supply unit 10. The receiving unit 30 generates a beat signal BS by mixing the obtained received signal RS with the basic transmission signal TS1 received from the supply unit 10. The receiving unit 30 outputs the generated beat signal BS to the processing unit 40.

  The processing unit 40 receives the beat signal BS from the receiving unit 30, and generates a two-dimensional spectrum PS from the received beat signal BS. The processing unit 40 detects a distance-turning ghost from among peaks included in the two-dimensional spectrum PS. The processing unit 40 generates target data that is information relating to the peak indicating the target, and outputs the generated target data to the vehicle ECU 47.

  The vehicle ECU 47 uses the target data received from the processing unit 40 for, for example, ACC (Adaptive Cruise Control) and PCS (Pre-crash Safety System).

{3.2. Configuration of Supply Unit 10１０
The supply unit 10 includes a signal generation unit 11, a phase change unit 12, a delay circuit 13, branch units 14 and 15, and a memory 16.

  When receiving the transmission instruction signal from the transmission control unit 41, the signal generation unit 11 generates a basic transmission signal TS1 and outputs the generated basic transmission signal TS1 to the branching unit 14. The splitter 14 splits the basic transmission signal TS1 received from the signal generator 11 and outputs the split signal to the phase changer 12 and the delay circuit 13.

  The phase changing unit 12 gives a periodic phase change to the basic transmission signal TS1 received from the branching unit 14 based on the pattern table 17 stored in the memory 16. The phase change unit 12 outputs the basic transmission signal TS1 to which the periodic phase change has been given to the transmission antenna 22 as the phase change transmission signal TS2.

  The delay circuit 13 delays the basic transmission signal TS1 so that the transmission timing of the basic transmission wave TW1 matches the transmission timing of the phase-change transmission wave TW2. The delay circuit 13 outputs the delayed basic transmission signal TS1 to the branching unit 15. The splitter 15 splits the basic transmission signal TS1 received from the delay circuit 13 and outputs the split signal to a plurality of mixers 32 included in the transmission antenna 21 and the receiver 30.

  The memory 16 is a nonvolatile storage device, for example, a flash memory. The memory 16 stores a pattern table 17.

{3.3. Configuration of transmitting section 20｝
The transmission unit 20 includes transmission antennas 21 and 22. The transmission antenna 21 receives the basic transmission signal TS1 from the branching unit 15, and transmits the received basic transmission signal TS1 as a basic transmission wave TW1. The transmission antenna 22 receives the phase change transmission signal TS2 from the phase change unit 12, and transmits the received phase change transmission signal TS2 as a phase change transmission wave TW2. This eliminates the need to combine the basic transmission signal TS1 with the phase-change transmission signal TS2, so that the configuration of the radar device 100 can be simplified.

{3.4. Configuration of receiving section 30｝
The receiving unit 30 includes a plurality of receiving antennas 31, a plurality of mixers 32, and a plurality of A / D converters 33. One receiving antenna 31 corresponds to one mixer 32 and one A / D converter 33.

  The reception antenna 31 receives the reception wave RW, and converts the received reception wave RW into a reception signal RS. The reception antenna 31 outputs the reception signal RS to the mixer 32.

  The mixer 32 generates a beat signal BS by mixing the reception signal RS received from the reception antenna 31 with the basic transmission signal TS1 received from the branching unit 15. The beat signal BS generated by the mixer 32 is an analog signal. The mixer 32 outputs the generated beat signal BS to the A / D converter 33.

  The A / D converter 33 digitizes the beat signal BS received from the mixer 32 based on a preset sampling frequency. The A / D converter 33 outputs the digitized beat signal BS to the processing unit 40.

{3.5. Configuration of processing unit 40４０
The processing unit 40 includes a transmission control unit 41, a conversion unit 42, a preprocessing unit 43, a ghost detection unit 44, an azimuth estimation unit 45, and a post-processing unit 46.

  The transmission control unit 41 outputs a transmission instruction signal for instructing transmission of the transmission wave TW to the signal generation unit 11 at a preset transmission interval ΔT. The set time interval ΔT is, for example, 50 msec.

  The conversion unit 42 performs fast Fourier transform on the beat signal BS received from the A / D converter 33. The conversion unit 42 acquires the two-dimensional spectrum PS as a result of the fast Fourier transform, and outputs the acquired two-dimensional spectrum PS to the preprocessing unit 43.

  The preprocessing unit 43 extracts a peak from the two-dimensional spectrum PS received from the conversion unit 42. The preprocessing unit 43 calculates the distance and the speed of the extracted peak based on the position of the extracted peak. Here, the distance is a relative distance of the target with respect to the radar device 100, and the speed is a relative speed of the target with reference to the radar device 100. The preprocessing unit 43 generates peak data PD in which the distance and speed of each peak are recorded, and outputs the generated peak data PD to the ghost detection unit 44.

  The ghost detection unit 44 detects a distance-turning ghost from the peaks extracted from the two-dimensional spectrum PS based on the peak data PD received from the preprocessing unit 43. The ghost detection unit 44 deletes the distance-turned ghost and the peak derived from the phase-change reflected wave RF2 from the peak data PD, and outputs the result to the direction estimation unit 45. The configuration of the ghost detection unit 44 and a method of detecting a distance-turning ghost will be described later.

  The azimuth estimating unit 45 receives the peak data PD from the ghost detecting unit 44, and estimates the azimuth of the target corresponding to the peak recorded in the received peak data PD. The azimuth estimation unit 45 uses a position estimation method such as EPSRIT (Estimation of Signal Parameters via Rotational Invariance Techniques), DBF (Digital Beam Forming), or MUSIC (Multiple Signal Classification). The azimuth estimating unit 45 records the azimuth estimation result of each peak in the peak data PD. The azimuth estimating unit 45 outputs the peak data PD recording the azimuth estimation result to the post-processing unit 46.

  The post-processing unit 46 receives the peak data PD from the direction estimation unit 45. The post-processing unit 46 performs post-processing of the peak recorded in the received peak data PD. The post-processing includes, for example, clustering, tracking processing, and unnecessary target removal processing. The post-processing unit 46 outputs the target data obtained as a result of the post-processing to the vehicle ECU 47.

Hereinafter, unless otherwise described, the peak data PD shows the recorded data the peaks included in the two-dimensional spectrum PS of the time T _k.

{3.6. Configuration of Ghost Detection Unit 44｝
FIG. 4 is a functional block diagram showing the configuration of the ghost detection unit 44 shown in FIG. Referring to FIG. 4, ghost detecting section 44 includes group generating section 441, peak selecting section 442, position estimating section 443, and determining section 444.

  The group generation unit 441 receives the peak data PD from the preprocessing unit 43, and determines whether two peaks included in the received peak data PD indicate the same target. Specifically, the group generation unit 441 specifies two peaks having the same distance. When the interval between the two specified peaks in the speed axis direction corresponds to the speed derived from the periodic phase change given to the basic transmission signal TS1, the group generation unit 441 determines that the two specified peaks are the same. Judge to indicate the mark. When determining that the two specified peaks indicate the same target, the group generation unit 441 generates a detection group G including the specified two peaks.

  The peak selection unit 442 selects a peak satisfying a predetermined selection condition from the two peaks included in the detection group G. The predetermined selection condition is determined based on a periodic phase change given to basic transmission signal TS1. In the present embodiment, the predetermined selection condition is a peak having the minimum speed among the peaks classified into the detection group G.

The position estimating unit 443 acquires the position of the selected peak selected by the peak selecting unit 442 from the peak data PD, and based on the acquired position of the selected peak, the selected peak is located in the two-dimensional spectrum PS at time T _k−1 . The appearing position ES is estimated.

When the two-dimensional spectrum PS at the time T _k−1 does not include a peak corresponding to the estimated position ES, the determination unit 444 determines that the selected peak is a distance-turning ghost. The determination unit 26 deletes the selected peak determined as the distance return ghost from the peak data PD and outputs it to the azimuth estimation unit 45.

In the radar apparatus 100, the phase change unit 12 by providing periodic phase changes in the basic transmission signal TS1, 2 peaks indicating the same target object is formed in a two-dimensional spectrum PS of the time T _k. One of the two peaks is a real image peak indicating a relative speed based on the radar device 100, and the other is a virtual image peak including a relative speed and a Doppler speed caused by a periodic phase change.

  The positional relationship between the real image peak and the virtual image peak in the velocity axis direction when the distance aliasing occurs is opposite to the positional relationship in the velocity axis direction between the real image peak and the virtual image peak when the distance aliasing does not occur. The radar apparatus 100 detects a distance-turning ghost using the above-described feature of the distance-turning. Therefore, it is possible to improve the detection accuracy of the distance return ghost.

｛4. Operation of radar apparatus 100 during transmission｝
{4.1. Transmission processing｝
FIG. 5 is a flowchart of a transmission process executed by the radar device 100 shown in FIG. The radar apparatus 100 repeatedly executes the transmission processing shown in FIG. 5 at a transmission interval ΔT.

  When the transmission interval ΔT has elapsed from the latest transmission time of the transmission wave TW, the transmission control unit 41 outputs a transmission instruction signal to the signal generation unit 11. When receiving the transmission instruction signal from the transmission control unit 41, the signal generation unit 11 generates a sweep signal (Step S11).

  In the sweep signal, the voltage increases at a fixed rate from the reference voltage with the passage of time, and repeats a rapid drop to the reference voltage when a time corresponding to one cycle of the preset sweep signal has elapsed.

  The signal generator 11 generates a continuous wave having a preset center frequency. The signal generation unit 11 generates a basic transmission signal TS1 by frequency-modulating a continuous wave using the sweep signal generated in step S11 (step S12). The basic transmission signal TS1 includes n chirp signals. Here, n is a natural number of 2 or more.

  The signal generation unit 11 outputs the generated basic transmission signal TS1 to the branch unit 14. The branching unit 14 branches the basic transmission signal TS1 received from the signal generation unit 11 into two, outputs one to the phase change unit 12, and outputs the other to the delay circuit 13.

  The phase changing unit 12 reads the pattern table 17 from the memory 16. The phase change unit 12 gives a periodic phase change to the basic transmission signal TS1 received from the branch unit 14 based on the read pattern table 17 (step S13). The phase change unit 12 supplies the basic transmission signal TS1 to which the periodic phase change has been given to the transmission antenna 22 as the phase change transmission signal TS2. The transmission antenna 22 converts the phase-change transmission signal TS2 received from the phase-change unit 12 into a phase-change transmission wave TW2 and transmits the same.

  The delay circuit 13 delays the basic transmission signal TS1 received from the branching unit 14 for a predetermined time, and outputs the delayed basic transmission signal TS1 to the branching unit 15. The branching unit 15 branches the basic transmission signal TS1 received from the delay circuit 13 into two, and outputs one to the transmission antenna 21 and the other to the plurality of mixers 32. The delay time corresponds to a time required for the phase change unit 12 to apply a periodic phase change to the basic transmission signal TS1. Thereby, the transmission timing of the basic transmission wave TW1 can be matched with the transmission timing of the phase-change transmission wave TW2.

{4.2. Operation of phase changing section 12｝
FIG. 6 shows an example of the pattern table 17 shown in FIG. Referring to FIG. 6, in pattern table 17, the phase change amounts in the first to fourth cycles are 0 °, 90 °, 180 °, and 270 °.

  FIG. 7 shows a phase change of the basic transmission signal TS1 when the phase change unit 12 uses the pattern table 17 shown in FIG. Referring to FIG. 7, basic transmission signal TS1 includes chirp signals C1 to Cn. The transmission period of the transmission wave TW is a period from time Ta to time Tb, that is, a period during which the chirp signals C1 to Cn are transmitted.

  The phase changing unit 12 adds the amount of phase change recorded in the pattern table 17 shown in FIG. 6 to the chirp signals C1 to Cn. Specifically, the phase changing unit 12 adds 0 ° to the phase of the chirp signal C1 in the first cycle. That is, the phase of the chirp signal C1 does not substantially change. Subsequently, the phase changing unit 12 adds 90 ° to the phase of the chirp signal C2 in the second cycle, adds 180 ° to the phase of the chirp signal C3 in the third cycle, and adds the phase of the chirp signal C4 in the fourth cycle. Is added to 270 °.

  The phase changing unit 12 repeats the process of adding the amount of phase change recorded in the pattern table 17 to the phase of the chirp signal after the fifth cycle. Specifically, the phase changing unit 12 adds 0 °, which is the phase change amount in the first cycle, to the phase of the chirp signal C5 in the fifth cycle. The phase changing unit 12 adds 90 °, which is the phase addition amount in the second cycle, to the phase of the chirp signal C6 in the sixth cycle. As a result, the phase changing unit 12 can change the phase of the basic transmission signal TS1 every four periods. That is, the phase of the phase change transmission signal TS2 periodically changes in a time corresponding to four cycles of the chirp signal.

  The periodic phase change using the pattern table 17 shown in FIG. 6 means that the phase of the basic transmission signal TS1 is increased by 90 ° every time one cycle of the chirp signal elapses. For example, the process of adding the phase of 0 ° to the phase of the chirp signal C5 is the same as adding a phase 360 ° larger than the phase of the chirp signal C1 to the chirp signal C5. The process of adding the 90 ° phase to the phase of the chirp signal C6 is the same as adding a phase 450 ° larger than the phase of the chirp signal C1 to the chirp signal C6.

{4.3. Effect of phase change｝
The phase changing unit 12 can add a virtual Doppler component to the basic transmission signal TS1 by giving a periodic change to the basic transmission signal TS1.

  Referring to FIG. 6, the phase change amount increases by 90 ° for each cycle. In other words, changing the phase of the basic transmission signal TS1 based on the pattern table 17 shown in FIG. 6 means that a virtual Doppler component whose phase changes by 90 ° every time one cycle of the chirp signal elapses, This means adding to the basic transmission signal TS1. The virtual Doppler component is independent of the moving speed of the radar device 100.

  When the vehicle 1A on which the radar device 100 is mounted is stopped, the basic transmission wave TW1 derived from the basic transmission signal TS1 does not include a Doppler component. On the other hand, the phase-change transmission wave TW2 derived from the phase-change transmission signal TS2 includes a virtual Doppler component generated due to a periodic phase change even when the vehicle 1A is stopped.

  The frequency of the virtual Doppler component depends on the cycle at which the phase of the chirp signal is changed, the rate of change in the amount of phase change per chirp signal, and the time for one cycle of the chirp signal. In the example shown in FIG. 6, the change rate of the phase change amount is a value obtained by subtracting the phase change amount in the M-th cycle from the phase change amount in the (M + 1) -th cycle. M is a natural number of 1 or more and K-1 or less, where K is a cycle for changing the phase of the chirp signal.

｛5. Operation of radar apparatus 100 during reception｝
{5.1. Reception processing｝
The reception antenna 31 receives the reception wave RW, and converts the received reception wave RW into a reception signal RS. Mixer 32 receives reception signal RS from reception antenna 31 and receives basic transmission signal TS1 from branching unit 15. The mixer 32 generates a beat signal BS by mixing the received signal RS with the basic transmission signal TS1. The beat signal BS generated by the mixer 32 is an analog signal.

  The A / D converter 33 converts the beat signal BS received from the mixer 32 into a digital signal. Specifically, the A / D converter 33 samples the analog beat signal BS at a predetermined sampling frequency, and digitizes the voltage value of the beat signal BS obtained by sampling. The A / D converter 33 converts the discretized voltage value into a binary number and generates a digitized beat signal BS.

{5.2. Generating target data｝
FIG. 8 is a flowchart of the target data generation processing executed by the processing unit 40. In the following description, the operation of the radar apparatus 100 in the case of transmitting the transmission wave TW at time T _k.

Referring to FIG. 8, conversion unit 42 receives digitized beat signal BS from A / D converter 33, and performs two-dimensional fast Fourier transform on the received beat signal BS (step S21). Since the two-dimensional fast Fourier transform is a known technique, a detailed description thereof will be omitted. Converter 42, as a result of the two-dimensional fast Fourier transform to obtain a two-dimensional spectrum PS of the time T _k.

Pre-processing unit 43, a two-dimensional spectrum PS of the time _{T k,} extracts a peak (step S22). The method for extracting the peak is not particularly limited. For example, the pre-processing unit 43, a peak having a larger power than a predetermined threshold value is extracted from the two-dimensional spectrum PS of the time T _k.

  The preprocessing unit 43 calculates the distance and the speed of the peak based on the position of the peak extracted in Step S22 (Step S23). The peak distance is calculated based on a predetermined frequency interval determined according to the distance resolution. The peak speed is calculated based on a predetermined frequency interval determined according to the speed resolution. The preprocessing unit 43 generates peak data PD in which the distance and speed of each peak are recorded, and outputs the generated peak data PD to the ghost detection unit 44.

FIG. 9 shows an example of the peak data PD generated by the preprocessing unit 43. Referring to FIG. 9, peak data PD records the distance and velocity of a peak extracted from two-dimensional spectrum PS. The peak data PD shown in FIG. 9 does not record the direction of each peak. This is because the azimuth of each peak has not been estimated when step S34 is performed. ID is identification information for uniquely identifying the peaks extracted from the 2-dimensional spectrum of a time T _k.

  The ghost detection unit 44 receives the peak data PD from the preprocessing unit 43, and detects a distance-turning ghost from among the peaks recorded in the received peak data PD (Step S24). Details of step S24 will be described later. The ghost detection unit 44 outputs, to the post-processing unit 46, the peak data PD from which the virtual image peak derived from the distance return ghost and the phase-change reflected wave RF2 has been deleted.

  The azimuth estimating unit 45 receives from the ghost detecting unit 44 the peak data PD from which the distance ghost and the virtual image peak have been deleted. The direction estimation unit 45 estimates the direction of each peak recorded in the received peak data PD. Since the azimuth estimation is a well-known technique, its detailed description is omitted. The azimuth estimating unit 45 adds the estimation result of the azimuth of each peak to the peak data PD and outputs the result to the post-processing unit 46.

  The post-processing unit 46 performs post-processing of the peak data PD received from the azimuth estimation unit 45 (Step S46). Target data is generated as an execution result of the post-processing (step S46). The post-processing is, for example, various processing such as clustering, tracking processing, removal of a stationary target, and grouping. Since these processes are well-known technologies, detailed descriptions thereof will be omitted.

｛6. Detection of ghosts that return distance
{6.1. Positional relationship between real image peak and virtual image peak｝
As described above, the radar apparatus 100, at time _{T k,} transmits a transmission wave TW, containing the basic transmission wave TW1 and phase change transmission wave TW2. As a result, two peaks indicating the same target object is extracted from the two-dimensional spectrum PS of the time T _k. One of the two peaks indicating the same target is a real image peak derived from the fundamental reflected wave RF1, and the other is a virtual image peak derived from the phase-change reflected wave RF2.

  Hereinafter, the positional relationship between the real image peak and the virtual image peak will be described, taking as an example the case where the radar apparatus 100 changes the phase of the basic transmission signal TS1 using the pattern table 17 shown in FIG.

FIG. 10 shows an example of the positional relationship between two peaks indicating the same target when the distance wrap has not occurred. 10, by omitting the display of the power shaft having a two-dimensional spectrum PS of the time T _k, shows easy to understand the positional relationship between the two peaks.

Referring to FIG. 10, a two-dimensional spectrum PS of the time _{T k} has two peaks Pa and Pb of a vehicle 2A showing a target. The peak Pa is a real image peak generated based on the fundamental reflected wave RF1. The peak Pb is a virtual image peak based on the phase-change reflected wave RF2.

  The peaks Pa and Pb have the same distance. The basic transmission wave TW1 and the phase-change transmission wave TW2 follow the same path from the radar device 100 to the vehicle 2A, and the basic reflection wave RF1 and the phase-change reflection wave RF2 remain the same until the vehicle 2A reaches the radar device 100. This is to pass the route.

  However, the speed of the peak Pb is different from the speed of the peak Pa. The speed difference between the peak Pa and the peak Pb is derived from the periodic phase change provided by the phase changing unit 12. For example, when a virtual Doppler component corresponding to 30 km / h is given to the basic transmission signal TS1 by a phase change based on the pattern table 17 shown in FIG. 6, the speed difference between the peak Pa and the peak Pb is 30 km / h. h. The details will be described below.

  The basic transmission wave TW1 does not include a virtual Doppler component corresponding to the periodic phase change given to the basic transmission signal TS1, and is reflected by the vehicle 2A. Therefore, the fundamental reflected wave RF1 includes a true Doppler component corresponding to the speed of the vehicle 2A, and does not include a virtual Doppler component. The speed of the peak Pa derived from the fundamental reflected wave RF1 indicates the speed of the vehicle 2A. Since the peak Pa indicates the distance and the true speed of the vehicle 2A, the peak Pa is called a real image peak.

  The phase change transmission wave TW2 includes a virtual Doppler component based on the periodic phase change given to the basic transmission signal TS1, and is reflected by the vehicle 2A. Therefore, the phase-change reflected wave RF2 includes a virtual Doppler component and a true Doppler component. The speed of the peak Pb derived from the phase-change reflected wave RF2 is a value obtained by adding the speed corresponding to the virtual Doppler component to the relative speed of the vehicle 2A. That is, since the peak Pb does not indicate the true speed of the vehicle 2A, it is called a virtual image peak.

  As a result, the interval between the peak Pa and the peak Pb in the velocity axis direction corresponds to the Doppler velocity derived from the periodic phase change corresponding to the basic transmission signal TS1.

  Note that when the phase change unit 12 increases the phase of the basic transmission signal TS1, the Doppler velocity becomes positive. As a result, the speed of the virtual image peak Pb becomes higher than the speed of the real image peak Pa.

  When the phase change unit 12 reduces the phase of the basic transmission signal TS1, the Doppler velocity becomes negative. For example, the phase change unit 12 can reduce the phase of the basic transmission signal TS1 by subtracting the phase change amount recorded in the pattern table 17 shown in FIG. 6 from the phases of the chirp signals C1 to Cn. In this case, the speed of the virtual image peak is smaller than the speed of the real image peak. Referring to FIG. 10, when phase changing section 12 reduces the phase of basic transmission signal TS1, the speed of peak Pb is −40 km / h.

{6.2. Changes in positional relationship due to distance wrapping｝
FIG. 11 shows a change in the positional relationship between the real image peak and the virtual image peak when the distance aliasing has occurred. Referring to FIG. 11, real image peak R and virtual image peak F are distance-turned ghosts. The real image peak R and the virtual image peak F indicate the vehicle 2A that is the target. The vehicle 2A is actually located farther than the maximum detection distance of the radar device 100.

  The peak R 'indicates the true position of the real image peak R. The peak F 'indicates the true position of the virtual image peak F. The peaks R 'and F' do not actually appear on the two-dimensional spectrum PS, but are shown in FIG. 11 for convenience of explanation. The distance of the peak F 'is the same as the distance of the peak R'. Since the phase changing unit 12 increases the phase of the basic transmission signal TS1, the speed of the peak F 'is higher than the speed of the peak R'.

  When the distance loopback occurs, the true peak distance is looped back from the solid line ML indicating the maximum detection distance, and the sign of the true peak speed is reversed. In other words, when a distance return occurs, the distance return ghost has a point-symmetrical relationship with a true peak around an intersection CR between the velocity axis and the solid line ML. In the example shown in FIG. 11, the real image peak R, which is a distance-turned ghost, has a point-symmetric relationship with the peak R 'about the intersection CR. The virtual image peak F, which is a distance-turning ghost, has a point-symmetric relationship with the peak F 'about the intersection CR. Although the phase changing unit 12 increases the phase of the basic transmission signal TS1, the speed of the real image peak R is smaller than the speed of the virtual image peak F.

  From the above, when the phase changing unit 12 increases the phase of the basic transmission signal TS1, the positional relationship between the real image peak R and the virtual image peak F has the following features (1) to (3).

  (1) Regardless of whether or not distance aliasing occurs, the distance of the virtual image peak F is the same as the distance of the real image peak R, and the speed difference between the real image peak R and the virtual image peak F is determined by the phase change unit 12. It corresponds to the Doppler velocity derived from the given periodic phase change.

  (2) When distance aliasing does not occur, the speed of the real image peak R is lower than the speed of the virtual image peak F.

  (3) When the distance aliasing occurs, the speed of the real image peak R is higher than the speed of the virtual image peak F.

  That is, the positional relationship in the velocity axis direction between the real image peak R and the virtual image peak F when the distance aliasing occurs is opposite to the positional relationship in the velocity axis direction between the real image peak R and the virtual image peak F when the distance aliasing does not occur. become.

  The ghost detecting unit 44 determines whether the real image peak R and the virtual image peak F are distance ghosts by utilizing the fact that the distance ghost is point-symmetric with the true peak when the distance wrap occurs. . Specifically, when the phase change unit 12 increases the phase of the basic transmission signal TS1, the ghost detection unit 44 extracts the two-dimensional spectrum PS from the two-dimensional spectrum PS by executing the following first to third processes. It is determined whether or not the resulting peak is a distance-turning ghost.

  (First Process) The ghost detection unit 44 specifies two peaks indicating the same target in the two-dimensional spectrum PS, and generates a detection group G including the two specified groups.

  (Second Process) The ghost detection unit 44 selects a peak having a low speed from the generated detection group G. Specifically, when the distance aliasing has not occurred, the real image peak is selected. When the distance aliasing occurs, the virtual image peak is selected. As described above, since the selected peak changes depending on whether or not the distance aliasing has occurred, it is possible to detect the distance aliasing ghost.

  (Third Process) The ghost detection unit 44 determines the type of the selected peak. If the selected peak is a virtual image peak, the ghost detection unit 44 determines that the two peaks specified in the first process are distance-turned ghosts. Hereinafter, the determination of the peak type will be described in detail.

{6.3. Determination of peak type｝
The third process for determining the type of the selected peak will be described with an example in which the phase changing unit 12 increases the phase of the basic transmission signal TS1. Details of the first processing and the second processing will be described later.

(When the selected peak is the real image peak)
Figure 12 shows a real image peaks of the two-dimensional spectrum PS of the time T _k, an example of a correspondence relationship between the real image peak time T _k-1 of the 2-dimensional spectrum PS. It is assumed that distance wrapping has not occurred at both times _Tk and _Tk-1 .

Referring to FIG. 12, peaks R (T _k ) and F (T _k ) are extracted from two-dimensional spectrum PS at time T _k and indicate vehicle 2A as a target. The peak R (T _k-1 ) is extracted from the two-dimensional spectrum PS at the time T _k-1 and indicates the target vehicle 2A. Both the peaks R (T _k ) and R (T _k−1 ) are real image peaks indicating the vehicle 2A. The peak F (T _k ) is a virtual image peak indicating the vehicle 2A. The ghost detection unit 44 determines that the type of the peak R (T _k ) is a virtual image peak by the following processing.

Since the peaks R (T _k ) and F (T _k ) indicate the same target, the ghost detection unit 44 determines the detection group G including the peaks R (T _k ) and F (T _k ). Generate (first process). The ghost detection unit 44 selects the peak R (T _k ) having the minimum speed from the generated detection group G (second processing).

The ghost detection unit 44 determines that the peak R (T _k ) selected in the second processing is a real image peak, and based on the determination result, determines whether the peaks R (T _k ) and F (T _k ) are distance-turned ghosts. It is not determined.

Ghost detection unit 44, to determine the type of the peak R _{(T k),} and estimates the position ES_R peak R _{(T k)} in the two-dimensional spectrum PS of the time _{T k-1.} The estimated position ES_R is calculated based on the speed of the peak R (T _k ).

Specifically, the ghost detection unit 44 sets the speed of the peak R (T _k ) to the speed of the estimated position ES_R. The transmission interval ΔT of the transmission wave TW is very short, for example, 50 msec. It is considered that the speed of the vehicle 2A hardly changes during a period until the transmission interval ΔT elapses. Therefore, the speed of the peak R (T _k ) is set as the speed of the estimated position ES_R.

Next, the ghost detection unit 44 acquires the moving distance ΔD2 of the peak R (T _k ) during the period from time T _k−1 to time T _k . The moving distance ΔD2 is obtained by multiplying the transmission interval ΔT by the speed of the peak R (T _k ). The ghost detecting unit 44 calculates the distance of the estimated position ES_R by adding the obtained moving distance ΔD2 to the distance of the peak R (T _k ).

  By calculating the distance and the speed of the estimated position ES_R in this way, the accuracy of the estimated position ES_R can be improved.

Ghost detection unit 44, with reference to the time _{T k-1} peak data PD, 2-dimensional spectrum PS of the time _{T k-1} to determine whether including the peak corresponding to the estimated position ES_R. The time T _k-1 peak data PD, which is recorded data of the distance and speed of the peaks extracted from the two-dimensional spectrum PS of the time T _k-1. As will be described later, the distance-turning ghost and the virtual image peak have already been deleted from the peak data PD at the time _Tk-1 . Therefore, the ghost detection unit 44 does not determine that the virtual image peak included in the two-dimensional spectrum PS at the time Tk _-1 corresponds to the estimated position ES_R.

Specifically, when the peak R (T _k−1 ) exists within the range of the circle having the radius R with respect to the estimated position ES_R, the ghost detection unit 44 determines that the peak R (T _k−1 ) is the estimated position. It is determined that it corresponds to ES_R. In FIG. 12, for convenience of explanation, the estimated position ES_R and the peak R (T _k−1 ) are exaggeratedly shown.

If the peak R _{(T k)} is a real peak estimated position ES_R corresponds to the peak R _{(T k-1)} included in the two-dimensional spectrum PS of the time _{T k-1.} For this reason, the ghost detection unit 44 determines that the peak R (T _k ) selected in the second processing is the real image peak.

Hereinafter, the reason why the estimated position ES_R corresponds to the peak R (T _k−1 ) when the peak R (T _k ) is the real image peak will be described.

The speed of the real image peak indicates the true speed of the target. Since the peak R (T _k ) is a real image peak, the moving distance ΔD2 obtained from the speed of the peak R (T _k ) is the true moving distance of the target in the period from time T _{k −1} to time T _k. Show. The distance of the real image peak indicates the true distance of the target. Since the peaks R (T _k ) and R (T _k−1 ) are real image peaks, the distance difference ΔD ₁ between the peaks R (T _k ) and R (T _k−1 ) is also the true moving distance of the target. Is shown. Since the moving distance ΔD2 obtained from the speed of the peak R (T _k ) matches the distance difference ΔD1, the distance of the peak R (T _k−1 ) matches the distance of the estimated position ES_R.

Since the transmission interval ΔT is a very short time, the speed difference between the peak R (T _k ) and the peak R (T _k−1 ) is small and can be ignored. Therefore, the speed of the peak R (Tk _-1 ) matches the speed of the estimated position ES_R.

Actually, the position of the estimated position ES_R may not completely coincide with the position of the peak R (T _k−1 ) due to an error or the like. For this reason, when the peak R (T _k−1 ) exists within the range of the circle having the radius R with respect to the estimated position ES_R, the ghost detection unit 44 sets the peak R (T _k−1 ) to the estimated position ES_R. Judge that it corresponds.

Thus, when the peak corresponding to the estimated position ES_R exists in the two-dimensional spectrum PS at the time T _k−1 , the speed of the peak R (T _k ) indicates the true speed of the target. As a result, it is determined that the peaks R (T _k ) and F (T _k ) constituting the detection group G are not distance-turning ghosts.

(When the selected peak is a virtual image peak)
Figure 13 shows a virtual image peaks of the two-dimensional spectrum PS of the time T _k, an example of a correspondence relationship between the virtual image peak time T _k-1 of the 2-dimensional spectrum PS. Assume that a distance wrap has occurred at both times _Tk and _Tk-1 .

Referring to FIG. 14, peaks R (T _k ), F (T _k ), and F (T _k−1 ) are distance-turned ghosts indicating vehicle 2A as a target. The peak R (T _k ) and the peak F (T _k ) are extracted from the two-dimensional spectrum PS at the time T _k . The peak F (T _k−1 ) is extracted from the two-dimensional spectrum PS at the time T _k−1 . The peak R (T _k ) is a real image peak, and the peaks F (T _k ) and F (T _k−1 ) are virtual image peaks.

Incidentally, at the time of starting the processing for detecting the distance folding ghost from 2-dimensional spectrum PS of the time T _k, peak data PD at time T _k-1 does not record the distance folding ghost and the virtual image peaks. However, for convenience of explanation, the peak F (T _k−1 ) corresponding to the peak F (T _k ) at the time T _k is shown in FIG.

Since the peaks R (T _k ) and F (T _k ) indicate the same target, the ghost detection unit 44 determines the detection group G including the peaks R (T _k ) and F (T _k ). Generate (first process). The ghost detection unit 44 selects the peak F (T _k ) having the minimum speed from the peaks R (T _k ) and F (T _k ) indicating the same target (second processing).

The ghost detection unit 44 determines that the peak F (T _k ) is a virtual image peak by the following processing, and detects the peaks R (T _k ) and F (T _k ) as distance-turned ghosts based on the determination result. I do.

Ghost detection unit 44, based on the speed of the peak F _{(T k),} to calculate the estimated position ES_F peak F _{(T k-1).} The calculation of the estimated position ES_F is the same as the calculation of the above-described estimated position ES_R, and thus a detailed description thereof will be omitted.

If the peak F _{(T k)} is a virtual image peak estimated position ES_F does not coincide with the peak F _{(T k-1).} Hereinafter, the reason will be described.

Since both the peaks F ( _Tk ) and F ( _Tk-1 ) are virtual image peaks, the distance between the peaks F ( _Tk ) and F ( _Tk-1 ) is the true distance of the vehicle 2A. Show. Therefore, the distance difference ΔD3 between the peak F (T _k ) and the peak F (T _k−1 ) indicates the true moving distance of the vehicle 2A.

However, the speed at the peak F (T _k ) is not the true speed of the vehicle 2A. The target moving distance ΔD4 obtained from the speed of the peak F (T _k ) does not indicate the true moving distance of the vehicle 2A. Therefore, the estimated position ES_F does not coincide with the position of the peak F (T _k−1 ). The ghost detection unit 44 cannot detect a peak corresponding to the peak F (T _k ) from the two-dimensional spectrum PS at the time T _k−1 , and thus determines that the peak F (T _k ) is a virtual image peak. . As a result, the peaks R (T _k ) and F (T _k ) constituting the detection group G are determined to be distance-turned ghosts.

{6.4. Operation of ghost detection unit 44４４
FIG. 14 is a flowchart of the ghost detection process (step S24) shown in FIG. Ghost detection unit 44, when acquiring the peak data PD to a two-dimensional spectrum PS of the time T _k from the pre-processing unit 43 starts the processing shown in FIG. 14.

  The group generation unit 441 generates a detection group G from the peak data PD (Step S501). Step S501 corresponds to the above-described first processing.

  Specifically, the group generation unit 441 specifies two peaks indicating the same target from among the peaks recorded in the peak data PD, and generates a detection group G including the specified two groups. I do. The group generation unit 441 outputs the generated detection group G to the peak selection unit 442. If a plurality of targets exist in the detection range of the radar device 100, a plurality of detection groups are generated in step S501.

  For example, when the detection group G is generated from the peak data PD illustrated in FIG. 9, the group generation unit 441 determines that the peak of the ID “P31” and the peak of the ID “P33” have the same distance. . When the difference between the peak speed of the ID “P31” and the peak speed of the ID “P33” corresponds to the Doppler speed derived from the periodic phase change given to the basic transmission signal TS1 by the phase changing unit 12, the group generation is performed. The unit 441 determines that these two peaks indicate the same target. The group generation unit 441 generates a detection group G including a peak of ID “P31” and a peak of ID “P33”. In addition, it is determined that the peak of ID “32” and the peak of ID “36” indicate the same target, and a detection group G including the peak of ID “32” and the peak of ID “36” is generated. You.

  The peak selection unit 442 selects one detection group from the group G generated by the group generation unit 441 (Step S502). The peak selection unit 442 selects the peak with the lowest speed in the selected one detection group (Step S503). Step S503 corresponds to the above-described second processing. The peak selecting unit 442 notifies the position estimating unit 443 of the ID of the selected peak.

The position estimating unit 443 estimates a position where the selected peak appears in the two-dimensional spectrum PS at the time T _k−1 (step S504). The position estimating unit 443 outputs the estimated position acquired in step S504 to the determining unit 444. The determining unit 444 determines whether the selected peak is a real image peak based on the estimated position received from the position estimating unit 443 (Step S505). Steps S504 and S505 correspond to the above-described third processing.

  If the selected peak is a real image peak (Yes in step S505), the determination unit 444 determines that the peaks forming the detection group selected in step S502 are not distance-turning ghosts (step S506). In this case, the determination unit 444 deletes the virtual image peak constituting the detection group selected in step S502 from the peak data PD (step S507). This is because a virtual image peak that is not a distance-turned ghost does not have a true velocity of the target.

  On the other hand, when the selected peak is a virtual image peak (No in step S505), the determining unit 444 determines that the peak forming the detection group selected in step S502 is a distance-turning ghost (step S508). The determining unit 444 deletes the information of the peak determined to be a wrap-around distance ghost from the peak data PD (step S509).

  The peak selection unit 442 determines whether all the detection groups G have been selected (Step S510). If all the detection groups have been selected (Yes in step S510), the identification of the types of all the peaks recorded in the peak data PD has been completed. Therefore, the ghost detection unit 44 ends the processing illustrated in FIG.

  If all the detection groups G have not been selected (No in step S510), there is a peak whose type is not specified. In this case, the peak selection unit 442 executes Step S502 again.

  As described above, the radar device 100 generates a phase change transmission signal TS2 by giving a periodic phase change to the basic transmission signal TS1, and outputs the basic transmission signal TS1 and the phase change transmission signal TS2 as the transmission wave TW. . When giving a periodic phase change to the basic transmission signal TS1, the radar device 100 increases the phase of the basic transmission signal TS1. The radar apparatus 100 specifies two peaks indicating the same target among the peaks extracted from the two-dimensional spectrum PS generated from the beat signal BS, and generates a detection group including the specified two peaks. I do. The radar device 100 selects a peak having the minimum speed from the detection groups. The radar device 100 determines whether a peak corresponding to the selected peak exists in the two-dimensional spectrum PS detected last time. Thereby, the radar device 100 can detect the distance return ghost with high accuracy.

[Second embodiment]
{1. Configuration of radar apparatus 100A｝
FIG. 15 is a functional block diagram showing a configuration of a radar device 100A according to the second embodiment of the present invention. Referring to FIG. 15, radar apparatus 100 </ b> A detects a distance-turning ghost, similarly to radar apparatus 100 according to the first embodiment. The radar device 100A includes a supply unit 10A, a transmission unit 20A, a reception unit 30, and a processing unit 40.

  The supply unit 10A generates the basic transmission signal TS1 and the phase change transmission signals TS2 to TS3. The supply unit 10A outputs the generated basic transmission signal TS1 to the transmission unit 20A and the reception unit 30, and outputs the generated phase change transmission signals TS2 to TS3 to the transmission unit 20A.

  The transmission unit 20A includes transmission antennas 21 to 23. The transmission antenna 21 transmits the basic transmission signal TS1 received from the supply unit 10A as a basic transmission wave TW1. The transmitting antenna 22 transmits the phase-change transmission signal TS2 received from the supply unit 10A as a phase-change transmission wave TW2. The transmission antenna 23 transmits the phase-change transmission signal TS3 received from the supply unit 10A as a phase-change transmission wave TW3. In the present embodiment, transmission wave TW includes basic transmission wave TW1, and phase-change transmission waves TW2 to TW3.

  The supply unit 10A includes phase change units 121 and 122 instead of the phase change unit 12. The supply unit 10A includes a memory 16A instead of the memory 16.

  The memory 16A stores pattern tables 17 and 18. The pattern tables 17 and 18 store different phase change patterns.

  The phase change unit 121 generates a phase change transmission signal TS2 by giving a periodic phase change to the basic transmission signal TS1 received from the branch unit 14. The phase changing unit 121 uses the pattern table 17 when giving a periodic phase change. The phase change unit 121 outputs the generated phase change transmission signal TS2 to the transmission antenna 22.

  The phase change unit 122 generates a phase change transmission signal TS3 by giving a periodic phase change to the basic transmission signal TS1 received from the branch unit 14. The phase changing unit 122 uses the pattern table 18 when giving a periodic phase change. The phase change unit 122 outputs the generated phase change transmission signal TS3 to the transmission antenna 23.

{2. Generation of phase change transmission signal｝
FIG. 16 shows an example of the phase change pattern recorded in the pattern table 18 shown in FIG. Referring to FIG. 16, pattern table 18 records a phase change pattern in which the amount of phase change increases by 45 ° every time one cycle of the chirp signal elapses. Specifically, the amount of phase change in each of the first to eighth cycles is 0 °, 45 °, 90 °, 135 °, 180 °, 225 °, 270 °, and 315 °.

  The phase change unit 122 generates the phase change transmission signal TS3 by adding the phase change amounts of the first to eighth cycles recorded in the pattern table 18 to the phases of the chirp signals C1 to C8. That is, the phase of the phase change transmission signal TS3 periodically changes in a time corresponding to eight cycles of the chirp signal.

  The generation of the phase-change transmission signal TS2 by the phase-change unit 121 is the same as that in the above-described embodiment, and thus a detailed description thereof is omitted.

  The phase of the phase change transmission signal TS2 changes by 90 ° per one cycle of the chirp signal. The phase of the phase change transmission signal TS3 changes by 45 ° per one cycle of the chirp signal. Therefore, the virtual Doppler frequency included in the phase change transmission wave TW2 is twice the virtual Doppler frequency included in the phase change transmission wave TW3.

  As described above, even when two or more phase change transmission signals are generated, it is possible to detect a distance-turning ghost. Moreover, since the radar apparatus 100A does not combine the basic transmission signal TS1 and the phase change transmission signals TS2 to TS3, the configuration of the radar apparatus can be simplified.

{3. Operation of radar apparatus 100A｝
The radar apparatus 100A performs the same processing as the radar apparatus 100 according to the first embodiment, and detects a distance-turning ghost. In other words, even when two or more phase change transmission signals are generated, whether a plurality of peaks are distance-turning ghosts based on the type of the smallest peak among the plurality of peaks indicating the same target Can be determined.

  In the following description, the phase change transmission signal TS2 includes a Doppler frequency corresponding to 40 km / h, and the phase change transmission signal TS3 corresponds to 20 km / h due to the phase change of each of the phase change units 121 and 122. Suppose that it contains a Doppler frequency that In this case, the interval between the Doppler frequencies included in the basic transmission signal TS1, the phase change transmission signal TS2, and the phase change transmission signal TS3 is 20 km / h.

  FIG. 17 is a diagram showing an example of the arrangement of peaks when the phase of the basic transmission signal TS1 is changed based on the pattern tables 17 and 18 shown in FIG. Referring to FIG. 17, peaks Pa to Pc are extracted from the two-dimensional spectrum PS acquired this time. Among the peaks Pa to Pc, the speed of the peak Pa is the minimum, and the speed of the peak Pc is the maximum.

  The group generation unit 441 determines that the peaks Pa to Pc have the same distance. The speed difference ΔV1 between the peak Pa and the peak Pb is 20 km / h, and the speed difference ΔV2 between the peak Pb and the peak Pc is 20 km / h. The speed differences ΔV1 and ΔV2 correspond to the above-mentioned Doppler frequency interval (20 km / h). As a result, the group generation unit 441 determines that the peaks Pa to Pc indicate the same target, and generates a detection group G including the peaks Pa to Pc.

  The peak selector 442 selects the peak Pa having the minimum speed in the detection group G shown in FIG. When the distance aliasing has not occurred, the peak Pa is a real image peak. When the distance aliasing has occurred, the peak Pa is a virtual image peak. The position estimating unit 443 estimates the position of the peak Pa in the previous two-dimensional spectrum PS. The determination unit 444 determines whether a peak corresponding to the estimated position ES exists in the previous two-dimensional spectrum PS. Thereby, the radar apparatus 100A can determine whether or not the peaks Pa to Pc that form the detection group G are distance-turning ghosts.

[Third Embodiment]
{1. Configuration of radar device 100B｝
FIG. 18 is a functional block diagram showing a configuration of a radar device 100B according to the third embodiment of the present invention. With reference to FIG. 18, the radar device 100B detects a distance-turning ghost, similarly to the radar device 100 according to the first embodiment. The radar device 100B includes a supply unit 10B, a transmission unit 20B, a reception unit 30, and a processing unit 40.

  The supply unit 10B generates the basic transmission signal TS1 and the combined transmission signal TSB. The supply unit 10B outputs the generated basic transmission signal TS1 to the reception unit 30, and outputs the generated combined transmission signal TSB to the transmission unit 20B.

  Transmitting section 20B includes a transmitting antenna 21B. The transmission antenna 21B transmits the combined transmission signal TSB received from the supply unit 10B as a transmission wave TW.

  The supply unit 10B includes a signal generation unit 11, a phase change unit 12B, a branch unit 14B, and a memory 16B.

  The signal generation unit 11 outputs the basic transmission signal TS1 to the branch unit 14B. The splitter 14B splits the basic transmission signal TS1 received from the signal generator 11, and outputs the split signal to the phase changer 12B and the plurality of mixers 32.

  The phase changing unit 12B gives a periodic phase change and amplitude change to the basic transmission signal TS1 received from the branching unit 14B, and generates a combined transmission signal TSB. The phase changing unit 12B outputs the generated combined transmission signal TSB to the transmission antenna 21B. The memory 16B stores a pattern table 17B. The pattern table 17B is used for generating the composite transmission signal TSB.

  Since the configurations of the receiving unit 30 and the processing unit 40 in the radar device 100B are the same as those in the first embodiment, detailed description thereof will be omitted.

{2. Operation of phase changing section 12B｝
The phase changing unit 12B gives a periodic phase change to the basic transmission signal TS1 using the amount of phase change recorded in the pattern table 17B.

  FIG. 19 is a diagram showing an example of the pattern table 17B shown in FIG. Referring to FIG. 19, pattern table 17B records a phase change amount and an amplitude change amount.

  As the amount of phase change, eight phases to be added to each of the eight consecutive chirp signals among the chirp signals C1 to Cn included in the basic transmission signal TS1 are recorded. Specifically, the amount of phase change in the first and fifth cycles is 0 °. The amount of phase change in the second and sixth cycles is 45 °. The phase addition amount in the third cycle is 90 °. The amount of phase addition in the fourth and eighth periods is 315 °. The phase addition amount in the seventh cycle is 270 °.

  The amplitude change amount indicates the magnitude of the amplitude of each of the eight consecutive chirp signals among the chirp signals C1 to Cn. The amplitude change amount in the first cycle is 3, indicating that the amplitude of the chirp signal C1 is tripled. That is, the amplitude of the chirp signal C1 included in the composite transmission signal TSB is three times the amplitude of the chirp signal C1 included in the basic transmission signal TS1. The amplitude change amount in the second and eighth cycles is 2.41. The amplitude change amount in the third and seventh cycles is 1. The amplitude change amount in the fourth and sixth cycles is 0.41. The amplitude change amount in the fifth cycle is 0.

  That is, the phase changing unit 12B periodically changes the phase and the amplitude of the basic transmission signal TS1 for a time corresponding to eight cycles of the chirp signal to generate the combined transmission signal TSB. The combined transmission signal TSB corresponds to a signal obtained by combining the basic transmission signal TS1 and the phase change transmission signals TS2 to TS3. The details will be described below.

  FIG. 20 is a diagram showing a basic pattern used for generating the pattern table 17B shown in FIG. The phase change amount and the amplitude change amount shown in FIG. 19 are generated by combining the first to third basic patterns shown in FIG. In each of the first to third basic patterns, the amount of phase change added to the chirp signal in the first to eighth cycles increases at a fixed rate.

  In the first basic pattern, the amount of phase change increases by 0 ° every time one cycle of the chirp signal elapses. That is, in the first basic pattern, the phase change amounts in the first to eighth cycles are all 0 °.

  In the second basic pattern, the amount of phase change increases by 45 ° every time one cycle of the chirp signal elapses. Therefore, the phase change amounts in the first to eighth cycles in the second basic pattern are 0 °, 45 °, 90 °, 135 °, 180 °, 225 °, 270 °, and 315 °. The second basic pattern is the same as the pattern table 18 shown in FIG.

  In the third basic pattern, the amount of phase change increases by 90 ° every time one cycle of the chirp signal elapses. Therefore, the phase addition amounts in the first to eighth cycles in the third basic pattern are 0 °, 90 °, 180 °, 270 °, 360 °, 450 °, 540 °, and 630 °. The third basic pattern is the same as the pattern table 17 shown in FIG.

  By combining the first to third basic patterns on a complex plane, a phase change pattern shown in FIG. 19 is generated. FIG. 21 is a diagram illustrating an example of combining basic patterns. Referring to FIG. 21, vectors B1 to B3 respectively correspond to first to third basic patterns. The magnitudes of the vectors B1 to B3 correspond to the amplitudes of the chirp signals C1 to Cn included in the basic transmission signal TS1, and are normalized to 1.

  The phases of the first cycle of the first to third basic patterns are all 0 °. Accordingly, when the first cycle of the first to third basic patterns is combined, the phase of the combined vector E of the vectors B1 to B3 is 0 °. The magnitude of the composite vector E is 3. The phase and magnitude of the composite vector E are set to the phase change amount and the amplitude change amount of the first cycle in the pattern table 18B.

  The phases of the second cycle of the first to third basic patterns are 0 °, 45 °, and 90 °. Therefore, when the first cycle of the first to third basic patterns is combined, the phase of the combined vector E of the vectors B1 to B3 is 45 °. The amplitude of the composite vector E is 2.41. The phase and magnitude of the composite vector E are set to the phase change amount and the amplitude change amount in the second cycle in the pattern table 18B.

  The phases of the third cycle of the first to third basic patterns are 0 °, 90 °, and 180 °. Since the vector B1 and the vector B3 cancel each other, the vector B2 becomes the composite vector E. Therefore, the phase of the composite vector E is 90 °, and the amplitude of the composite vector E is 1. The phase and magnitude of the composite vector E are set to the phase change amount and the amplitude change amount in the third cycle in the pattern table 18B.

  Hereinafter, by synthesizing the phases of the first to third basic patterns for each cycle, it is possible to calculate the synthesized phase and the synthesized amplitude in each cycle. The calculated combined phase and combined amplitude are used as the phase change amount and the amplitude change amount shown in FIG. Since the first basic pattern has a phase change amount of 0 °, the phase change transmission signal generated based on the first basic pattern corresponds to the basic transmission signal TS1. The second basic pattern is the same as the pattern table 17 shown in FIG. 6, and the third basic pattern is the same as the pattern table 18 shown in FIG. Therefore, the combined transmission signal TSB is equivalent to a signal obtained by combining the basic transmission signal TS1 and the phase change transmission signals TS2 to TS3. In other words, transmission wave TW according to the present embodiment includes basic transmission wave TW1 and phase-change transmission waves TW2 to TW3 shown in FIG. Therefore, the radar apparatus 100B can detect a distance-turning ghost, similarly to the radar apparatus 100.

  The phase changing unit 12B changes the amplitude of the combined transmission signal TSB based on the first to third basic patterns, thereby obtaining the amplitudes of the basic transmission signal TS1 and the phase-change transmission signals TS2 to TS3 included in the combined transmission signal TSB. Can be prevented from changing for each chirp signal. This can suppress the temporal fluctuation of the power of the real image peak and the virtual image peak, and thus prevent the real image peak and the virtual image peak from being instantaneously detected from the spectrum. Therefore, it is possible to stably judge whether or not a distance-turning ghost has occurred over time.

  Further, since the radar apparatus 100B only needs to include at least one transmitting antenna regardless of the number of phase change patterns, the configuration of the transmitting unit 20 can be simplified.

  Although an example has been described with the present embodiment where transmitting section 20B includes only transmitting antenna 21B, transmitting section 20B may include a plurality of transmitting antennas that transmit combined transmission signal TSB as transmission wave TW.

[Modification]
In the above-described embodiment, an example has been described in which, when the phase changing unit 12 increases the phase of the basic transmission signal TS1, the peak selecting unit 442 selects the peak having the minimum speed in the detection group G. Not limited. The peak selector 442 may select the peak having the maximum speed in the detection group G. In this case, when the selected peak is the real image peak, the determination unit 444 determines that the peak included in the detection group is a distance-turning ghost.

  When the phase changing unit 12 reduces the phase of the basic transmission signal TS1, the ghost detection unit 44 selects the peak having the maximum speed in step S503, and determines whether the selected peak is a virtual image peak. Judge it. If the selected peak is a virtual image peak, the ghost detection unit 44 determines that the peak included in the detection group is a distance-turning ghost.

  When the phase change unit 12 reduces the phase of the basic transmission signal TS1, the ghost detection unit 44 selects the peak with the minimum speed in step S503, and determines whether the selected peak is a real image peak. Is also good. If the selected peak is a real image peak, the ghost detection unit 44 determines that the peak included in the detection group is a distance-turned ghost.

That is, the ghost detection unit 44 selects a peak that satisfies the selection condition determined based on the periodic phase change from the detection group, and the two-dimensional spectrum PS at the time T _k−1 includes a peak corresponding to the estimated position. It may be determined whether or not.

Further, in the above-described embodiment, an example has been described in which the ghost detection unit 44 determines whether or not the two-dimensional spectrum PS at the time T _k−1 includes a peak corresponding to the estimated position, but is not limited thereto. . Ghost detection unit 44 estimates the position of the selected peak in the two-dimensional spectrum PS of the time T _k and different times, it may be determined whether the 2-dimensional spectrum PS of different times comprises a peak corresponding to the estimated position . The different time is not particularly limited as long as it is the transmission time of the transmission wave TW. For example, different time is the transmission time of the transmitted wave TW, which is set immediately after time T _k.

  Further, in the above-described embodiment, a case has been described where the radar apparatus 100A generates two phase change transmission signals, but the radar apparatus 100 may generate three or more phase change transmission signals. The pattern table 17B may record a combined phase and a combined amplitude obtained by combining two basic patterns, or may record a combined phase and a combined amplitude obtained by combining four or more basic patterns.

  In the above-described embodiment, an example has been described in which the ghost detection unit 44 deletes the peak included in the detection group from the peak data PD when determining that the peak included in the detection group is a distance-turning ghost. Not limited. The ghost detection unit 44 may correct the distance of the real image peak determined to be the distance-turning ghost in the peak data PD based on the positional relationship between the distance-turning ghost and the true peak position.

  In the above embodiment, the radar device 100 determines whether the peak forming the detection group G is a distance-turning ghost when the distance of the peak forming the detection group is within a predetermined range based on the maximum detection distance. It does not need to be determined.

The radar apparatus 100 can time T _k and T _k-1 both at a distance aliasing occurs, or, assuming that the distance folded in both the time T _k and T _k-1 does not occur, the distance folding ghost To detect. However, when the distance of the peaks constituting the detection group is a value close to the maximum detection distance, it is assumed that a distance wrap occurs at _one of the times T _k and T _k−1 and a distance wrap does not occur at the other. Is done. When the radar device 100 detects the above-mentioned distance turning ghost in this situation, erroneous detection may occur. Therefore, when the difference between the distance of the peaks constituting the detection group and the maximum detection distance is larger than a predetermined value, the radar apparatus 100 may execute the above-described distance-return ghost detection processing. Thereby, erroneous detection can be prevented.

  Further, in the above embodiment, each functional block of the processing unit 40 may be individually formed into one chip by a semiconductor device such as an LSI, or may be formed into one chip so as to include a part or the whole. The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

  Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

  A part or all of the processing executed by each functional block of the processing unit 40 may be realized by a program. Part or all of the processing of the functional blocks is performed by a central processing unit (CPU) in a computer. Further, programs for performing the respective processes are stored in a storage device such as a hard disk and a ROM, and are executed by being read from the ROM or from the RAM.

  Further, each process of the above embodiment may be realized by hardware, or may be realized by software (including a case where it is realized together with an OS (Operating System), middleware, or a predetermined library). . Further, it may be realized by mixed processing of software and hardware.

  For example, when each functional block of the above-described embodiment (including the modified example) is realized by software, the hardware configuration illustrated in FIG. 7 (for example, a CPU, a ROM, a RAM, Each of the functional units may be realized by software processing using a hardware configuration connected by the software.

  The execution order of the processing method in the above embodiment is not necessarily limited to the description of the above embodiment, and the execution order may be changed without departing from the gist of the invention.

  A computer program that causes a computer to execute the above-described method and a computer-readable recording medium that records the program are included in the scope of the present invention. Here, examples of the computer-readable recording medium include a flexible disk, hard disk, CD-ROM, MO, DVD, DVD-ROM, DVD-RAM, large-capacity DVD, next-generation DVD, and semiconductor memory. .

  The computer program is not limited to the one recorded on the recording medium, and may be transmitted via an electric communication line, a wireless or wired communication line, a network represented by the Internet, or the like.

  The embodiment of the present invention has been described above, but the above-described embodiment is merely an example for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit thereof.

100, 100A, 100B Radar device 10, 10A, 10B Supply unit 11 Signal generation unit 11
12, 121, 122, 12B Phase changing section 20, 20A, 20B Transmitting section 30 Receiving section 40 Processing section 42 Converting section 44 Ghost detecting section 441 Group generating section 442 Peak selecting section 443 Position estimating section 444 Determination section

Claims (8)

A signal generation unit that generates a basic transmission signal,
A phase change unit that generates a phase change transmission signal by giving a periodic phase change to the basic transmission signal,
A transmission unit that outputs the basic transmission signal and the phase change transmission signal as a transmission wave,
From the basic transmission signal and the reception signal acquired by the reception unit, a conversion unit that generates a spectrum including a distance axis corresponding to the distance of the target and a speed axis corresponding to the speed of the target,
A ghost detection unit that determines whether the peak included in the spectrum is a distance-turning ghost,
The ghost detector,
When a plurality of peaks having the same distance are specified from the spectrum at the first time, and the interval in the speed axis direction at the specified plurality of peaks corresponds to a speed difference derived from the periodic phase change, the specifying is performed. Group generation unit for classifying into a detection group including a plurality of peaks,
Among a plurality of peaks included in the detection group, a peak selection unit that selects a peak that satisfies a selection condition determined based on the periodic phase change,
A position estimating unit that estimates a position of the selected peak in a spectrum at a second time different from the first time based on the position of the selected peak selected by the peak selecting unit;
A determining unit that determines that the peak included in the detection group is a distance-turning ghost when the spectrum at the second time does not include a peak corresponding to the estimated position of the selected peak. The radar device according to claim 1,
The position estimating unit calculates a moving distance of the selected peak in a period from the first time to the second time based on a speed of the selected peak, and calculates an estimated position of the selected peak by the calculated moving distance. A radar device that estimates based on The radar device according to claim 1,
The basic transmission signal is
Including multiple chirp signals,
The radar device, wherein, when the phase changing unit increases the phase of each of the plurality of chirp signals, the peak selecting unit selects a peak having the smallest speed among the plurality of peaks included in the detection group. The radar device according to claim 1, wherein:
The radar device, wherein when the spectrum at the second time does not include a peak located within a predetermined range based on the estimated position of the selected peak, the selected peak is determined to be a distance-turning ghost. The radar device according to any one of claims 1 to 4,
The transmitting unit includes:
A first transmission antenna that outputs the basic transmission signal as a basic transmission wave,
A second transmission antenna that outputs the phase-change transmission signal as a phase-change transmission wave. The radar device according to any one of claims 1 to 4,
The phase change unit generates a combined transmission signal by combining the basic transmission signal and the phase change transmission signal,
The transmitting unit includes:
A radar device including a transmission antenna that outputs a combined transmission signal generated by the phase change unit as a transmission wave. The radar device according to claim 6, wherein
The basic transmission signal is
A plurality of chirp signals,
The phase change unit adds the phase change amount set for each of the plurality of chirp signals to each of the plurality of chirp signals, so that the periodic change is added to the transmission signal generated by the signal generation unit. And changing the amplitude of the chirp signal included in the synthesized transmission signal based on the phase change amount. Generating a basic transmission signal;
Generating a phase change transmission signal by giving a periodic phase change to the basic transmission signal,
Outputting the basic transmission signal and the phase change transmission signal as a transmission wave,
Using the basic transmission signal and the reception signal obtained by the reception antenna, generating a spectrum including a distance axis corresponding to the distance of the target and a speed axis corresponding to the speed of the target,
Determining whether the peak included in the spectrum is a distance-turned ghost,
When a plurality of peaks having the same distance are specified from the spectrum at the first time, and the interval in the speed axis direction at the specified plurality of peaks corresponds to a speed difference derived from the periodic phase change, the specifying is performed. Generating a detection group that includes the plurality of peaks that have been obtained;
Of a plurality of peaks included in the detection group, selecting a selected peak that satisfies a selection condition determined based on the periodic phase change,
Estimating the position of the selected peak in a spectrum at a second time different from the first time based on the position of the selected peak;
When the spectrum at the second time does not include a peak corresponding to the estimated position of the selected peak, determining that the peak included in the detection group is a distance-turning ghost.

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