WO2021234998A1 - Radar device - Google Patents

Radar device Download PDF

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Publication number
WO2021234998A1
WO2021234998A1 PCT/JP2021/001394 JP2021001394W WO2021234998A1 WO 2021234998 A1 WO2021234998 A1 WO 2021234998A1 JP 2021001394 W JP2021001394 W JP 2021001394W WO 2021234998 A1 WO2021234998 A1 WO 2021234998A1
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WO
WIPO (PCT)
Prior art keywords
radar device
phase information
chirp
unit
speed
Prior art date
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PCT/JP2021/001394
Other languages
French (fr)
Japanese (ja)
Inventor
美裕 中尾
幸徳 赤峰
堅一 嶋田
浩司 黒田
Original Assignee
日立Astemo株式会社
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Priority to DE112021001476.5T priority Critical patent/DE112021001476T5/en
Publication of WO2021234998A1 publication Critical patent/WO2021234998A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/08—Systems for measuring distance only
    • G01S13/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G01S13/36—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated with phase comparison between the received signal and the contemporaneously transmitted signal
    • G01S13/38—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated with phase comparison between the received signal and the contemporaneously transmitted signal wherein more than one modulation frequency is used
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/08—Systems for measuring distance only
    • G01S13/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G01S13/34—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
    • G01S13/343—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal using sawtooth modulation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/08—Systems for measuring distance only
    • G01S13/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G01S13/34—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
    • G01S13/347—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal using more than one modulation frequency
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/42—Simultaneous measurement of distance and other co-ordinates
    • G01S13/44—Monopulse radar, i.e. simultaneous lobing
    • G01S13/4454—Monopulse radar, i.e. simultaneous lobing phase comparisons monopulse, i.e. comparing the echo signals received by an interferometric antenna arrangement
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/35—Details of non-pulse systems
    • G01S7/352—Receivers
    • G01S7/354—Extracting wanted echo-signals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
    • H01Q21/08—Arrays of individually energised antenna units similarly polarised and spaced apart the units being spaced along or adjacent to a rectilinear path
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/26—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
    • H01Q3/2605—Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/93—Radar or analogous systems specially adapted for specific applications for anti-collision purposes
    • G01S13/931—Radar or analogous systems specially adapted for specific applications for anti-collision purposes of land vehicles
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/35—Details of non-pulse systems
    • G01S7/352—Receivers
    • G01S7/356—Receivers involving particularities of FFT processing

Definitions

  • the present invention relates to a radar device using a plurality of antennas.
  • a chirp signal whose frequency changes continuously is transmitted, and the distance, speed, and azimuth angle of the target are detected using the received signal and the transmitted signal due to the reflected wave of the target.
  • the target detection by radar there is a limit value of the speed that can be correctly detected, and when a target exceeding the speed is detected, it is detected at an erroneous speed as a turnaround.
  • the azimuth angle estimation of the target when the element spacing of the receiving antenna is larger than half of the wavelength, there is a limit value in the azimuth angle that can be correctly estimated, and it is detected as an erroneous direction.
  • the distance between the receiving antennas it is necessary to set the distance between the receiving antennas to half a wavelength or less.
  • the size of the antenna is half a wavelength or more, it is physically impossible to make the antenna interval less than half a wavelength.
  • the maximum detection speed is made different by changing the idle transmission time of the chirp signal.
  • the speeds detected by each of a plurality of chirp signals having different maximum detection speeds are compared, and if the detection speeds are equal, it can be determined that the correct speed without turning back can be detected.
  • the detected speed is return, it can be determined that the detected speed is return because the maximum detection speed of each chirp signal is different and the speed detection result is deviated.
  • Non-Patent Document 1 As a countermeasure technique for angle turning, in Non-Patent Document 1, the receiving antennas are arranged at unequal intervals. By arranging the receiving antennas at unequal intervals, angle folding can be eliminated even if the antenna intervals are half a wavelength or more.
  • the empty chirp time of the chirp signal with a long charp cycle is set to the empty feed time of the chirp signal with a short chirp cycle in order to reliably detect the speed turnaround. It needs to take much longer than time. Then, with the chirp signal having the longer chirp cycle, the time during which the signal is not transmitted becomes longer, and the overall received power decreases.
  • Non-Patent Document 1 it is possible to suppress the angle turning by making the receiving antenna intervals unequal as a countermeasure against the angle turning, but the antenna density becomes sparse and the alias noise increases.
  • An object of the present invention is to solve the above-mentioned problems and to provide a radar device that simultaneously suppresses false detection of a target due to angle turning and speed turning.
  • a transmission unit that alternately transmits a plurality of chirp waves having the same bandwidth but different center frequencies from a single transmitting antenna, and a target by the chirp waves.
  • the speed of the target is detected based on the receiver equipped with multiple receiving antennas that receive the reflected waves of, and the received signals from the reflected waves with different center frequencies, and the speed turnaround is corrected based on the speed detection result.
  • a radar device including a speed calculation unit and an orientation estimation unit that acquires phase information from a plurality of receiving antennas and detects the orientation angle of a target based on the acquired phase information.
  • the present invention it is possible to detect the correct speed of a target moving at a speed exceeding the maximum detection speed of a single chirp, and it is possible to suppress the angle turning that occurs when the element spacing of the receiving antenna is longer than half a wavelength.
  • the figure which shows the chirp signal which concerns on embodiment of this invention.
  • the figure which shows the radar apparatus which concerns on embodiment of this invention.
  • the figure which shows the structure of the analog part of the radar apparatus which concerns on embodiment of this invention.
  • the figure which shows the detection of a speed turn back The figure which shows the structure of the direction estimation part.
  • Example 1 is an example of a radar device using an FM-CW (Frequency Modulated Continuous Wave) method.
  • FM-CW Frequency Modulated Continuous Wave
  • a radar device using the FM-CW method detects a target distance, speed, and azimuth angle by transmitting and receiving a chirp signal whose frequency changes continuously with time.
  • FIG. 1 shows a chirp wave having a center frequency f, a chirp period t, and a modulation bandwidth B.
  • the transmitted chirp signal is reflected by the target, and the reflected wave is received by the receiving antenna.
  • the signal received by the receiving antenna is mixed with the transmission signal by the mixer to form a beat signal.
  • the beat signal output from the mixer is A / D converted and transmitted to the signal processing unit.
  • the received chirp wave is received through a route that is twice the distance to the target.
  • a frequency difference occurs between the transmitted chirp wave and the received chirp wave depending on the distance. Based on this frequency difference, the distance to the target can be obtained.
  • the distance to the target will change between one chirp and the next, so between the beat signal obtained from one transmit / receive chirp and the beat signal obtained from the next transmit / receive chirp.
  • a phase difference occurs in.
  • the relative velocity of the target can be obtained from this phase difference.
  • the distance and relative speed of the detected target are calculated by performing time / frequency FFT of the beat signal with each receiving antenna.
  • the phase of the received signal differs between the antennas depending on the direction of arrival of the reflected wave from the target.
  • the directional angle of the target is obtained by using an azimuth estimation algorithm such as DBF (Digital BeamForming) or Capon using the received phase information of each receiving antenna.
  • DBF Digital BeamForming
  • the element spacing of the receiving antennas is larger than half of the wavelength in the estimation of the azimuth angle of the target, it is possible to distinguish between the azimuth angle in which the reception phase difference between adjacent antennas is ⁇ + 2n ⁇ and the azimuth angle in which the phase difference is ⁇ . It is necessary to set the interval between the receiving antennas to half a wavelength or less in order to detect it as an incorrect direction.
  • a high-gain, wide-band antenna may have a size of half a wavelength or more, and it is physically impossible to install the antennas at intervals of half a wavelength or less. Further, in order to increase the angular resolution, it is necessary to widen the aperture length, so that a huge number of antennas are required even for an antenna that can be installed at half a wavelength or less.
  • the maximum detection speed can be made different by using a plurality of chirp signals having different chirp periods. The speeds detected by each of the plurality of chirp signals are compared, and if the detection speeds are equal, it is determined that the correct speed without turning back can be detected. When the detected speed is return, it is determined that the detected speed is return because the maximum detection speed of each chirp signal is different and the speed detection result is deviated.
  • Another method of generating chirp signals having different periods is a method of making the chirp period different by changing the slope of the frequency change of the chirp signal as shown in Patent Document 2.
  • Non-Patent Document 1 There is a technology to arrange the antenna intervals at unequal intervals as a countermeasure technology for angle turning.
  • angle folding can be eliminated even if the antenna intervals are half a wavelength or more, but the antenna density becomes sparse when the aperture length is widened. If this happens, aliases will increase and the accuracy of azimuth angle estimation will decrease.
  • the radar device of this embodiment has a transmitter that alternately transmits a plurality of chirp waves having substantially the same bandwidth but different center frequencies from a single transmitting antenna, and a plurality of reflected waves from a target. It includes a receiving unit that receives signals from an antenna and a signal processing unit that detects the distance, speed, and azimuth angle of a target. The signal processing unit detects the speed of the target based on each of the received signals from the reflected waves having different center frequencies, and corrects the speed turnaround based on the speed detection result. Further, the phase information of a plurality of receiving antennas is acquired, the phase information is corrected based on the center frequency, and the directional angle of the target is detected based on the corrected phase information.
  • FIG. 3 shows a suitable configuration of the radar device according to this embodiment.
  • the radar device 1 includes an analog unit 2 including an array antenna and a digital unit 3 connected to the analog unit.
  • the analog unit is an analog circuit, and includes a transmitting unit 4 including a transmitting antenna and a receiving unit 5 including a receiving antenna.
  • the digital unit includes a frequency control unit 6, a signal processing unit 7, and a storage unit 8.
  • the frequency control unit 6 controls the center frequency of the chirp signal.
  • the signal processing unit 7 includes a distance / speed detection unit 9, a turn-back correction speed calculation unit 10, and an azimuth estimation unit 11.
  • the distance / speed detection unit 9 includes a circuit that performs FFT processing from the received signal input from the analog unit 2.
  • the turn-back correction speed calculation unit 10 is a part that determines the presence or absence of speed turn-back from a plurality of speed detection results and calculates the correct speed of the target.
  • the azimuth estimation unit 11 is a part for calculating the azimuth of the target, and obtains the azimuth angle of the target from the phase information sequences of a plurality of received signals.
  • the radar device 1 outputs the detected distance information, speed information, and azimuth angle information as target detection information.
  • FIG. 4 shows the details of the configuration of the analog unit 2.
  • the analog unit 2 includes a transmission unit 4 and a reception unit 5.
  • the transmission unit 4 has a synthesizer 41, an amplifier 42, and a transmission antenna 43.
  • the synthesizer 41 generates a chirp signal having a center frequency specified by the frequency control unit 6 described later. This signal is amplified through the amplifier 42 and transmitted as a transmission signal from the transmission antenna 43. The transmitted signal is reflected by the target and becomes a reflected wave.
  • the receiving unit 5 has a plurality of receiving antennas 51, an amplifier 52 for each antenna, a mixer 53, a filter 54, and an A / D converter 55.
  • the receiving antenna 51 receives the reflected wave whose transmission signal is reflected by the target.
  • the signal received by the receiving antenna 51 is amplified by the amplifier 52 and output to the mixer 53.
  • the mixer 53 receives a transmission signal from the transmission unit 4, mixes the reception signal input from the reception antenna 51 to generate a beat signal, and outputs the beat signal to the A / D converter 55.
  • the beat signal has a frequency that is the difference between the frequency of the transmission signal and the frequency of the reception signal.
  • the digital unit 3 has a frequency control unit 6, a signal processing unit 7, and a storage unit 8.
  • the frequency control unit 6 controls the modulation bandwidth, center frequency, and chirp period of the chirp signal including the first modulated wave and the second modulated wave as shown in FIG.
  • the frequency control unit of the radar device alternately transmits the chirp wave modulated by the first modulation method and the chirp wave modulated by the second modulation method.
  • the first modulation method is a chirp wave having a modulation bandwidth B1, a center frequency f1, and a chirp period t1
  • the second modulation method is a chirp wave having a modulation bandwidth B2, a center frequency f2, and a chirp period t2.
  • the chirp period t1 and the chirp period t2 are substantially the same.
  • bandwidths B1 and B2 of the first modulation method and the second modulation method are equal, but the difference between B1 and B2 may be the bandwidth / (number of samples in chirp ⁇ 2) or less, which is caused by the device or the like. Needless to say, some errors may be included.
  • the detection distance by the first modulated wave, the speed and the detection distance by the second modulated wave, and the speed are linked after the FFT.
  • the difference between the maximum detection distance R1max of the first modulated wave and the maximum detection distance R2max of the second modulated wave is 1 ⁇ 2 or more of the distance resolution, it becomes difficult to connect the two results. Therefore, the difference between B1 and B2 should be bandwidth / (number of samples in chirp ⁇ 2) or less.
  • the band error is 0.73 MHz or less.
  • the center frequency f1 of the first modulated wave and the center frequency f2 of the second modulated wave are separated by at least the modulation bandwidth B.
  • the chirp periods t1 and t2 need to be values such that the maximum detection speeds V1max and V2max are not equal between the first modulated wave and the second modulated wave.
  • the signal processing unit 7 has a distance speed detection unit 9, a turn-back correction speed calculation unit 10, and an azimuth estimation unit 11.
  • the reception signal of the first modulated wave is input from the reception unit 5 to the distance velocity detection unit 9.
  • the distance velocity detection unit 9 performs a time frequency FFT on the received signal of the first-order modulated wave, and obtains a signal after FFT processing.
  • the power spectrum of distance and velocity can be obtained by FFT processing. Based on the distance / velocity power spectrum obtained here, the distance R1 and the velocity V1 are selected from the distance bin and the velocity bin, and the distance R1 and the velocity V1 are transmitted to the memory unit 8. This process is similarly performed for the received signal of each receiving antenna.
  • the distance velocity detection unit 9 also transmits the phase information sequence a1 of the received signal of the first modulated wave to the memory unit.
  • the received signal of the second modulated wave is input from the receiving unit 5 to the distance velocity detecting unit 9.
  • the distance velocity detection unit 9 calculates the distance R2 and the velocity V2 by performing the time frequency FFT in the same manner as the processing for the first modulated wave, and transmits the phase information sequence a2 corresponding to the distance R2 and the velocity V2 to the memory unit.
  • the distance R to the target is determined by the result of.
  • the maximum detection speed required to obtain the speed from the reflected waves of the first modulated wave and the second modulated wave is determined by receiving the center frequencies f1 and f2 from the frequency control unit.
  • the folding correction speed calculation unit 10 reads the speed V1 calculated from the first modulated wave and the speed V2 calculated from the second modulated wave stored in the memory unit 8.
  • V1 and V2 match, the relative velocity V of the target can be determined to be V1 (or V2).
  • the velocities at n1 and n2 that satisfy this are determined as the relative velocities V of the target and output.
  • FIG. 5 shows an example of the distance and speed calculated by the distance speed detection unit 9 when the same target moving at a speed exceeding the maximum detection speeds V1max and V2max is detected in the first modulated wave and the second modulated wave. ing.
  • the correct velocity bin of the detected target is V1act.
  • the speed bin calculated by the distance speed detection unit 9 is V1est.
  • the correct velocity bin of the detected target is V2act in the targeting point by the second modulated wave.
  • the speed bin produced by the distance speed detection unit 9 is V2est.
  • FIG. 6A shows the details of the processing of the direction estimation unit 11, that is, the processing of correcting and combining the phase information sequences obtained from the received signals having different center frequencies based on the center frequency.
  • the directional estimation unit 11 includes a phase information coupling unit 12 and a directional calculation processing unit 13.
  • the phase information coupling unit 12 reads the center frequency f2 of the first modulated wave and the center frequency f2 of the second modulated wave from the frequency control unit. Further, the phase information sequences a1 and a2 of the signals received by the receiving antennas of the first modulated wave and the second modulated wave are read from the memory unit 8.
  • the antenna coordinates d are calculated based on the center frequencies f1 and f2, the phase information sequence a obtained by combining the two phase information sequences a1 and a2 is calculated, and the antenna coordinates d and the phase information sequence a are sent to the direction calculation processing unit 13. Output.
  • phase information coupling unit 12 normalizes the amplitude and phase of the received signal at a specific receiving antenna. Further, the phase information coupling unit calculates the directional angle from the phase information having different center frequencies, and corrects the virtual image generated by the directional angle.
  • the wavelength ⁇ 1 of the first modulated wave and the wavelength ⁇ 2 of the second modulated wave are obtained based on the center frequencies f1 and f2 acquired from the frequency control unit.
  • the antenna arrangement d1 for the wavelength ⁇ 1 of the first modulated wave and the antenna coordinates d2 for the wavelength ⁇ 2 of the second modulated wave are obtained. Specifically, it is obtained by dividing the antenna coordinates of the radar device by ⁇ 1 and ⁇ 2.
  • one coordinate of the element of d1 and the corresponding element of d2 are matched. Deviation of antenna gain occurs by changing the center frequency of the first modulated wave and the second modulated wave. It is necessary to normalize with one antenna in order to correct the antenna gain generated here. Therefore, one element of d1 and one element of d2 are shared.
  • the antenna coordinates d1 and the antenna coordinates d2 standardized according to the antenna coordinates d1 are combined to generate the antenna arrangement d as one coordinate sequence.
  • the received phase information string a2 of the second modulated wave is standardized according to the received phase information string a1 of the first modulated wave.
  • standardization is performed based on the elements corresponding to the antenna coordinates common in S125 among the phase information sequences a1 and a2.
  • phase information strings a1 and a2 are combined to generate a as one phase information sequence.
  • FIG. 7 shows the receiving antenna coordinates when the coordinates of the antennas of the received signal of the first modulated wave and the received signal of the second modulated wave are shared with the coordinates of the leftmost antenna.
  • the antenna coordinates 601 indicate the antenna coordinates d1
  • the antenna coordinates 602 indicate the antenna coordinates d2.
  • the phase information sequence a1 by the first modulated wave is considered to have been received at the antenna coordinates 601 corresponding to the first modulated wave of FIG. 7, and the phase information sequence a2 by the second modulated wave corresponds to the second modulated wave of FIG. It is considered to have been received at antenna coordinates 602.
  • the phase information sequence a2 is standardized so that one element corresponding to the leftmost antenna of the phase information sequence a1 and one element corresponding to the leftmost antenna of the phase information sequence a2 are equal.
  • the coordinate sequence d and the phase information sequence a in which the received signal of the first modulated wave and the received signal of the second modulated wave are combined are generated.
  • the directional calculation processing unit 13 calculates the directional angle of the target by the directional estimation algorithm such as DBF or Capon using the combined coordinate sequence d and the phase information sequence a.
  • the calculated azimuth angle is output from the radar device as target detection information.
  • the number of phase information elements that can be used for azimuth estimation is 12, whereas the chirp signal is transmitted as in the radar device according to the present embodiment.
  • the chirp signal to be used is a chirp signal having a first modulation wave and a second modulation having different center frequencies, the number of phase information elements that can be used for azimuth estimation increases to 23.
  • the maximum detection speed is V1max only for the first modulated wave, and the maximum detection speed is V2max only for the second modulated wave, but the maximum detection is performed by using the first modulated wave and the second volume tuning wave having different center frequencies.
  • the speed can be expanded to the least common multiple of V1max and V2max.
  • the maximum detection speed is increased by changing the center frequency. Since the chirps are different, the chirp airborne time can be shortened and the reception power can be prevented from decreasing. Therefore, it becomes possible to detect a target farther.
  • phase information that can be used to estimate the azimuth angle of the target is 2k-1.
  • the antenna / wavelength coordinate sequence d1 corresponding to the wavelength of the first modulated wave and the phase information sequence a1 and the antenna / wavelength coordinate sequence d2 corresponding to the wavelength of the second modulated wave and
  • the antenna / wavelength coordinate sequence d coupled from the phase information sequence a2 and the phase information sequence a it is possible to obtain phase information of an antenna interval that is narrower than the size of the antenna element and cannot be physically arranged.
  • the directional estimation based on the received signal of the first modulated wave and the directional estimation based on the received signal of the second modulated wave may be separately performed for the directional estimation twice.
  • FIG. 8 shows the processing in the case of performing the direction estimation twice.
  • the first azimuth estimation unit 101 that estimates the direction by the first modulated wave, a second azimuth estimation unit 102 by the second modulated wave, and a virtual image removing unit 103.
  • the first azimuth estimation unit 101 and the second azimuth estimation unit 102 perform high-resolution azimuth angle estimation processing such as Capon using the received phase sequence.
  • the virtual image removing unit 103 estimates the true direction of the target from the target direction estimated by the first direction estimation unit 101 and the target direction estimated by the second direction estimation unit 102. If there is no angle turning, the directional angle estimation result by the first modulated wave and the directional angle estimation result by the second modulated wave match. If the direction estimated by the first direction estimation unit and the direction estimated by the second direction estimation unit match, the direction detected by the first direction estimation unit and the second direction estimation unit is determined as the true target direction. .. On the other hand, when there is angle folding, the angle estimation direction by the first modulated wave and the angle estimation direction by the second modulated wave do not match. Therefore, when different azimuth angles are calculated by the first azimuth estimation unit and the second azimuth estimation unit, the target is deleted as a virtual image.
  • FIG. 9 shows an example of directional estimation when a virtual image due to angle folding is detected.
  • FIG. 9 is an example in which the true target direction is 45 degrees. That is, of the target azimuths estimated by the first azimuth angle estimation unit in FIG. 9, the right peak is the correct azimuth and the left peak shows a virtual image due to angle folding. Further, among the target azimuths estimated by the second azimuth angle estimation unit, the peak on the right is the correct azimuth and the peak on the left shows a virtual image due to angle folding.
  • the peak and virtual image of the correct target azimuth cannot be discriminated by only one of the first azimuth angle estimation unit and the second azimuth angle estimation unit.
  • the peaks on the right match and the peaks on the left deviate. From this result, it is determined that only the peak on the right is the correct target orientation.
  • the intervals between the receiving antennas in the receiving unit may be unequal. Even if the intervals between the receiving antennas are unequal, the distance and speed are obtained in the same way as the process described above.
  • the elements of the phase information sequences d1 and d2 are unequally spaced, but the calculation of the directional estimation is the same.
  • the chirp periods t1 and t2 of the chirp signal to be transmitted are not constant and may be unequal intervals. By transmitting the chirp signal while changing the chirp periods t1 and t2, more accurate speed turnaround correction becomes possible.

Abstract

Provided is a radar device that reduces velocity aliasing and angular aliasing. This radar device comprises: a transmission unit 4 for temporally alternatingly transmitting, from a single transmission antenna, a plurality of chirp waves that have the same bandwidth but different central frequencies; a reception unit 5 comprising a plurality of reception antennas for receiving chirp waves that have been reflected by a target; an aliasing-corrected velocity calculation unit 10 for detecting the velocity of the target on the basis of respective reception signals from the reflected waves having the different central frequencies and correcting velocity aliasing on the basis of the result of the velocity detection; and an azimuth estimation unit 11 for acquiring phase information using the plurality of reception antennas and calculating the azimuth angle of the target on the basis of the acquired phase information. The azimuth estimation unit corrects phase information sequences, which are obtained from the reception signals having the different central frequencies, on the basis of the central frequencies, combines the phase information sequences, and uses the resulting combined phase information sequence to carry out target azimuth estimation processing.

Description

レーダ装置Radar device
　本発明は複数アンテナを用いたレーダ装置に関する。 The present invention relates to a radar device using a plurality of antennas.
　レーダを用いた物標検知では、周波数が連続的に変化するチャープ信号を送信し、物標による反射波による受信信号と送信信号を用いて物標の距離、速度、方位角度を検知することができる。しかし、レーダによる物標検知では、正しく検知できる速度の限界値があり、その速度を超えた物標を検知した場合、折返しとして誤った速度で検知する。また、物標の方位角度推定において、受信アンテナの素子間隔が波長の半分よりも大きい場合、正しく推定できる方位角度に限界値があり、誤った方位として検知する。そのため、物標の方位を正しく推定するためには受信アンテナの間隔を半波長以下にする必要がある。しかし、アンテナの大きさが半波長以上の場合、アンテナ間隔を半波長以下にすることが物理的に不可能である。また、角度分解能を上げる場合、開口長を広くとる必要があるため、半波長以下で設置可能なアンテナであっても、膨大なアンテナ数が必要となる。 In target detection using radar, a chirp signal whose frequency changes continuously is transmitted, and the distance, speed, and azimuth angle of the target are detected using the received signal and the transmitted signal due to the reflected wave of the target. can. However, in the target detection by radar, there is a limit value of the speed that can be correctly detected, and when a target exceeding the speed is detected, it is detected at an erroneous speed as a turnaround. Further, in the azimuth angle estimation of the target, when the element spacing of the receiving antenna is larger than half of the wavelength, there is a limit value in the azimuth angle that can be correctly estimated, and it is detected as an erroneous direction. Therefore, in order to correctly estimate the orientation of the target, it is necessary to set the distance between the receiving antennas to half a wavelength or less. However, when the size of the antenna is half a wavelength or more, it is physically impossible to make the antenna interval less than half a wavelength. Further, in order to increase the angular resolution, it is necessary to widen the aperture length, so that a huge number of antennas are required even for an antenna that can be installed at half a wavelength or less.
　速度折返しの対策技術として例えば特許文献１ではチャープ信号の空送時間を変えることで最大検知速度を異ならせている。最大検知速度の異なる複数のチャープ信号でそれぞれ検知した速度を比較し、検知速度が等しければ、折返しのない正しい速度を検知できていると判定できる。検知した速度が折返しだった場合、それぞれのチャープ信号の最大検知速度が異なることで速度の検知結果にずれが生じるため、検知した速度が折返しであると判定できる。 As a countermeasure technology for speed turning back, for example, in Patent Document 1, the maximum detection speed is made different by changing the idle transmission time of the chirp signal. The speeds detected by each of a plurality of chirp signals having different maximum detection speeds are compared, and if the detection speeds are equal, it can be determined that the correct speed without turning back can be detected. When the detected speed is return, it can be determined that the detected speed is return because the maximum detection speed of each chirp signal is different and the speed detection result is deviated.
　また、角度折返しの対策技術として、非特許文献１では受信アンテナを不等間隔に配置している。受信アンテナ配置を不等間隔にすることでアンテナ間隔が半波長以上であっても角度折返しを解消することができる。 Further, as a countermeasure technique for angle turning, in Non-Patent Document 1, the receiving antennas are arranged at unequal intervals. By arranging the receiving antennas at unequal intervals, angle folding can be eliminated even if the antenna intervals are half a wavelength or more.
特開２０１９－３９６８６号公報Japanese Unexamined Patent Publication No. 2019-39686 特開２０１９－１８４３７０号公報Japanese Unexamined Patent Publication No. 2019-184370
  特許文献１のように、速度折返し対策としてチャープ信号の空送時間を変える場合、速度折返しを確実に検知するために長いチャープ周期のチャープ信号の空送時間を短いチャープ周期のチャープ信号の空送時間よりも大幅に長くとる必要がある。すると、チャープ周期の長い方のチャープ信号では信号を送信しない時間が長くなり、全体の受信電力が低下する。 When the empty chirp time of the chirp signal is changed as a measure against speed turnaround as in Patent Document 1, the empty chirp time of the chirp signal with a long charp cycle is set to the empty feed time of the chirp signal with a short chirp cycle in order to reliably detect the speed turnaround. It needs to take much longer than time. Then, with the chirp signal having the longer chirp cycle, the time during which the signal is not transmitted becomes longer, and the overall received power decreases.
　また、非特許文献１のように、角度折返し対策として受信アンテナ間隔を不等間隔にすることで角度折返しを抑圧することはできるが、アンテナ密度は疎な状態になり、エイリアス雑音が増大する。 Further, as in Non-Patent Document 1, it is possible to suppress the angle turning by making the receiving antenna intervals unequal as a countermeasure against the angle turning, but the antenna density becomes sparse and the alias noise increases.
　本発明は、上記の課題を解決し、角度折返し及び速度折返しによる物標の誤検知を同時に抑圧するレーダ装置を提供することを目的とする。 An object of the present invention is to solve the above-mentioned problems and to provide a radar device that simultaneously suppresses false detection of a target due to angle turning and speed turning.
  上記課題を解決するために、本発明においては、単一の送信アンテナから帯域幅が同一で中心周波数が異なる複数のチャープ波を時間的に交互に送信する送信部と、チャープ波による物標からの反射波を受信する複数の受信アンテナを備えた受信部と、中心周波数が異なる反射波からの受信信号それぞれに基づいて、物標の速度を検出し、速度の検出結果に基づき速度折返しを補正する速度算出部と、複数の受信アンテナで位相情報を取得し、取得した位相情報に基づき物標の方位角度を検出する方位推定部と、を備えるレーダ装置を提供する。 In order to solve the above problems, in the present invention, from a transmission unit that alternately transmits a plurality of chirp waves having the same bandwidth but different center frequencies from a single transmitting antenna, and a target by the chirp waves. The speed of the target is detected based on the receiver equipped with multiple receiving antennas that receive the reflected waves of, and the received signals from the reflected waves with different center frequencies, and the speed turnaround is corrected based on the speed detection result. Provided is a radar device including a speed calculation unit and an orientation estimation unit that acquires phase information from a plurality of receiving antennas and detects the orientation angle of a target based on the acquired phase information.
  本発明により単一チャープの最大検知速度を超えた速度で移動する物標の正しい速度を検出でき、更に受信アンテナの素子間隔が半波長よりも長い場合に起こる角度折返しを抑圧することができる。 According to the present invention, it is possible to detect the correct speed of a target moving at a speed exceeding the maximum detection speed of a single chirp, and it is possible to suppress the angle turning that occurs when the element spacing of the receiving antenna is longer than half a wavelength.
ＦＭ－ＣＷ型式のチャープ信号を示す図。The figure which shows the chirp signal of FM-CW type. 本発明の実施形態に係るチャープ信号を示す図。The figure which shows the chirp signal which concerns on embodiment of this invention. 本発明の実施形態に係るレーダ装置を示す図。The figure which shows the radar apparatus which concerns on embodiment of this invention. 本発明の実施形態に係るレーダ装置のアナログ部の構成を示す図。The figure which shows the structure of the analog part of the radar apparatus which concerns on embodiment of this invention. 速度折返しの検知を示す図。The figure which shows the detection of a speed turn back. 方位推定部の構成を示す図。The figure which shows the structure of the direction estimation part. 方位推定部の処理を説明するための図。The figure for demonstrating the processing of the direction estimation part. 位相情報結合部における位相補正を示す図。The figure which shows the phase correction in a phase information coupling part. 変形例における方位推定部の構成を示す図。The figure which shows the structure of the direction estimation part in the modification. 変形例における方位推定の処理の一例を示す図。The figure which shows an example of the process of direction estimation in a modification.
  以下、発明を実施するための形態を図面に従い順次説明する。 Hereinafter, embodiments for carrying out the invention will be sequentially described with reference to the drawings.
  実施例１は、ＦＭ－ＣＷ（Ｆｒｅｑｕｅｎｃｙ　Ｍｏｄｕｌａｔｅｄ　Ｃｏｎｔｉｎｕｏｕｓ　Ｗａｖｅ）方式を用いたレーダ装置の実施例である。 Example 1 is an example of a radar device using an FM-CW (Frequency Modulated Continuous Wave) method.
　図１に示すように、ＦＭ－ＣＷ方式を用いたレーダ装置は、周波数が時間で連続的に変化するチャープ信号の送受信により、物標の距離、速度、方位角度を検知する。図１には中心周波数ｆ、チャープ周期ｔ、変調帯域幅Ｂのチャープ波を示している。 As shown in FIG. 1, a radar device using the FM-CW method detects a target distance, speed, and azimuth angle by transmitting and receiving a chirp signal whose frequency changes continuously with time. FIG. 1 shows a chirp wave having a center frequency f, a chirp period t, and a modulation bandwidth B.
　送信されたチャープ信号は物標で反射され、その反射波を受信アンテナで受信する。受信アンテナで受信した信号はミキサで送信信号とミキシングされ、ビート信号が形成される。ミキサから出力されたビート信号はＡ／Ｄ変換され信号処理部に伝送される。 The transmitted chirp signal is reflected by the target, and the reflected wave is received by the receiving antenna. The signal received by the receiving antenna is mixed with the transmission signal by the mixer to form a beat signal. The beat signal output from the mixer is A / D converted and transmitted to the signal processing unit.
　受信チャープ波は物標までの距離の2倍の距離の経路を通り受信される。ここで送信チャープ波と受信チャープ波との間に距離に応じて周波数差が生じる。この周波数差に基づき、物標までの距離を求めることができる。 The received chirp wave is received through a route that is twice the distance to the target. Here, a frequency difference occurs between the transmitted chirp wave and the received chirp wave depending on the distance. Based on this frequency difference, the distance to the target can be obtained.
　また、物標に相対速度がある場合、あるチャープと次のチャープの間にも物標との距離が変わるため、ある送受信チャープから得たビート信号と次の送受信チャープから得たビート信号の間に位相差が生じる。この位相差から物標の相対速度を求めることができる。
具体的にはビート信号を各受信アンテナで時間・周波数ＦＦＴを行うことにより検知した物標の距離と相対速度が算出される。 Also, if the target has a relative velocity, the distance to the target will change between one chirp and the next, so between the beat signal obtained from one transmit / receive chirp and the beat signal obtained from the next transmit / receive chirp. A phase difference occurs in. The relative velocity of the target can be obtained from this phase difference.
Specifically, the distance and relative speed of the detected target are calculated by performing time / frequency FFT of the beat signal with each receiving antenna.
　物標の方位角度を求める場合、複数の受信アンテナを用いる。複数の受信アンテナを用いた場合、物標からの反射波の到来方向により各アンテナで受信信号の位相に差が生じる。この各受信アンテナの受信位相情報を用いてＤＢＦ（Ｄｉｇｉｔａｌ Ｂｅａｍ Ｆｏｒｍｉｎｇ)やＣａｐｏｎなどの方位推定アルゴリズムを用いることにより物標の方位角度を求める。 When finding the azimuth angle of a target, use multiple receiving antennas. When a plurality of receiving antennas are used, the phase of the received signal differs between the antennas depending on the direction of arrival of the reflected wave from the target. The directional angle of the target is obtained by using an azimuth estimation algorithm such as DBF (Digital BeamForming) or Capon using the received phase information of each receiving antenna.
　ＦＭ－ＣＷ方式では正しく検知できる速度の限界値があり、その速度を超えた物標を検知した場合、折返しとして誤った速度で検知する。最大検知速度Ｖｍａｘは、Ｖｍａｘ＝λ／４ｔで示される。ここで、λは送信波の波長である。物標の相対速度がＶｍａｘを超えた場合、ビート信号の前後チャープの位相差がφ＋２ｎπとなる速度を、位相差がφとなる速度と誤って検知する。 In the FM-CW method, there is a limit value of the speed that can be detected correctly, and when a target that exceeds that speed is detected, it is detected at the wrong speed as a turnaround. The maximum detection speed Vmax is indicated by Vmax = λ / 4t. Here, λ is the wavelength of the transmitted wave. When the relative speed of the target exceeds Vmax, the speed at which the phase difference between the front and rear chirps of the beat signal is φ + 2nπ is erroneously detected as the speed at which the phase difference is φ.
　また、物標の方位角度推定において、受信アンテナの素子間隔が波長の半分よりも大きい場合、隣り合うアンテナの受信位相差がψ＋２ｎπとなる方位角度と位相差がψとなる方位角度の区別がつかず誤った方位として検知するため、受信アンテナの間隔は半波長以下にする必要がある。 In addition, when the element spacing of the receiving antennas is larger than half of the wavelength in the estimation of the azimuth angle of the target, it is possible to distinguish between the azimuth angle in which the reception phase difference between adjacent antennas is ψ + 2nπ and the azimuth angle in which the phase difference is ψ. It is necessary to set the interval between the receiving antennas to half a wavelength or less in order to detect it as an incorrect direction.
　しかし、高利得で広帯域のアンテナは、大きさが半波長以上の場合があり、アンテナを半波長以下の間隔で設置することが物理的に不可能である。また、角度分解能を上げる場合、開口長を広くとる必要があるため、半波長以下で設置可能なアンテナであっても、膨大なアンテナ数が必要となる。 However, a high-gain, wide-band antenna may have a size of half a wavelength or more, and it is physically impossible to install the antennas at intervals of half a wavelength or less. Further, in order to increase the angular resolution, it is necessary to widen the aperture length, so that a huge number of antennas are required even for an antenna that can be installed at half a wavelength or less.
　速度折返しの対策技術としてチャープ周期の異なる複数のチャープ信号を打ち分ける技術がある。チャープ周期の異なる複数のチャープ信号を用いることで最大検知速度を異ならせることができる。複数のチャープ信号でそれぞれ検知した速度を比較し、検知速度が等しければ、折返しのない正しい速度を検知できていると判定する。検知した速度が折返しだった場合、それぞれのチャープ信号の最大検知速度が異なることで速度の検知結果にずれが生じるため、検知した速度が折返しであると判定する。 There is a technology to separate multiple chirp signals with different chirp cycles as a countermeasure technology for speed turnaround. The maximum detection speed can be made different by using a plurality of chirp signals having different chirp periods. The speeds detected by each of the plurality of chirp signals are compared, and if the detection speeds are equal, it is determined that the correct speed without turning back can be detected. When the detected speed is return, it is determined that the detected speed is return because the maximum detection speed of each chirp signal is different and the speed detection result is deviated.
　周期の異なるチャープ信号の生成方法は２通りある。一つは特許文献１に示されているように空送時間を変えることでチャープ周期を変える方法である。しかし、速度折返しを確実に検知するために長いチャープ周期のチャープ信号の空送時間を短いチャープ周期のチャープ信号の空送時間よりも大幅に長くとる必要がある。すると、チャープ周期の長い方のチャープ信号では信号を送信しない時間が長くなり、全体の受信電力が低下する。受信電力の低下は検知精度の低下につながる。 There are two ways to generate chirp signals with different cycles. One is a method of changing the chirp cycle by changing the air-delivery time as shown in Patent Document 1. However, in order to reliably detect speed turnaround, it is necessary to set the idle time of the chirp signal with a long chirp cycle to be significantly longer than the idle time of the chirp signal with a short chirp cycle. Then, with the chirp signal having the longer chirp cycle, the time during which the signal is not transmitted becomes longer, and the overall received power decreases. A decrease in received power leads to a decrease in detection accuracy.
　周期の異なるチャープ信号の生成方法のもう一つは特許文献２に示されているようにチャープ信号の周波数変化の傾きを変えることでチャープ周期を異ならせる方法である。ここで、最大検知距離Ｒｍａｘがサンプリング周波数Ｆｓ、チャープ信号の周波数変化の傾きＳ、光の速度ｃを用いてＲｍａｘ＝Ｆｓ・ｃ／２Ｓで示されることと、距離分解能ＲｒｅｓがＲｒｅｓ＝ｃ／２Ｂで示されることから、チャープ信号の周波数変化の傾きに十分な差をとると、最大検知距離や距離分解能の差が生じる。最大検知距離や距離分解能に差があると、複数の変調波の検知結果から同一の物標を結び付けるための計算が複雑化する。 Another method of generating chirp signals having different periods is a method of making the chirp period different by changing the slope of the frequency change of the chirp signal as shown in Patent Document 2. Here, the maximum detection distance Rmax is indicated by Rmax = Fs · c / 2S using the sampling frequency Fs, the gradient S of the frequency change of the chirp signal, and the light velocity c, and the distance resolution Rres is Rres = c / 2B. As shown by, if a sufficient difference is taken in the slope of the frequency change of the chirp signal, a difference in the maximum detection distance and the distance resolution occurs. If there is a difference in the maximum detection distance or the distance resolution, the calculation for connecting the same target from the detection results of a plurality of modulated waves becomes complicated.
　角度折返しの対策技術としてアンテナ間隔を不等間隔に配置する技術がある。非特許文献１のように受信アンテナ配置を不等間隔にすることでアンテナ間隔が半波長以上であっても角度折返しを解消することができるが、開口長を広くする場合にアンテナ密度が疎となるとエイリアスが増大し、方位角度推定精度が低下する。 There is a technology to arrange the antenna intervals at unequal intervals as a countermeasure technology for angle turning. By arranging the receiving antennas at unequal intervals as in Non-Patent Document 1, angle folding can be eliminated even if the antenna intervals are half a wavelength or more, but the antenna density becomes sparse when the aperture length is widened. If this happens, aliases will increase and the accuracy of azimuth angle estimation will decrease.
　そこで、本実施例にかかるレーダ装置では図２に示すような中心周波数の異なる複数のチャープ信号を用いることで速度折返しによる誤検知と角度折返しによる誤検知の両方を解消する。本実施例のレーダ装置は、単一の送信アンテナから帯域幅が略同一で中心周波数が異なる複数のチャープ波を時間的に交互に送信する送信部と、物標からの反射波を複数の受信アンテナで受信する受信部と、物標の距離・速度・方位角度を検出する信号処理部とを備える。信号処理部では中心周波数が異なる反射波からの受信信号それぞれに基づいて、物標の速度を検出し、速度の検出結果に基づき速度折返しを補正する。また、複数の受信アンテナの位相情報を取得し、中心周波数に基づき位相情報を補正し、補正した位相情報に基づき物標の方位角度を検出する。 Therefore, in the radar device according to this embodiment, both false detection due to speed turning and false detection due to angle turning are eliminated by using a plurality of chirp signals having different center frequencies as shown in FIG. The radar device of this embodiment has a transmitter that alternately transmits a plurality of chirp waves having substantially the same bandwidth but different center frequencies from a single transmitting antenna, and a plurality of reflected waves from a target. It includes a receiving unit that receives signals from an antenna and a signal processing unit that detects the distance, speed, and azimuth angle of a target. The signal processing unit detects the speed of the target based on each of the received signals from the reflected waves having different center frequencies, and corrects the speed turnaround based on the speed detection result. Further, the phase information of a plurality of receiving antennas is acquired, the phase information is corrected based on the center frequency, and the directional angle of the target is detected based on the corrected phase information.
　［レーダ装置］
  図３は本実施例にかかるレーダ装置の好適な構成を示している。レーダ装置１はアレーアンテナを含むアナログ部２とアナログ部に接続されたデジタル部３とを含む。アナログ部はアナログ回路であり、送信アンテナを含む送信部４と受信アンテナを含む受信部５を含む。デジタル部は周波数制御部６と信号処理部７と記憶部８とを含む。 [Radar device]
FIG. 3 shows a suitable configuration of the radar device according to this embodiment. The radar device 1 includes an analog unit 2 including an array antenna and a digital unit 3 connected to the analog unit. The analog unit is an analog circuit, and includes a transmitting unit 4 including a transmitting antenna and a receiving unit 5 including a receiving antenna. The digital unit includes a frequency control unit 6, a signal processing unit 7, and a storage unit 8.
　周波数制御部６ではチャープ信号の中心周波数を制御する。信号処理部７は距離・速度検出部９と折返し補正速度算出部１０と方位推定部１１とを含む。距離・速度検出部９はアナログ部２から入力された受信信号からＦＦＴ処理を行う回路を含む。折返し補正速度算出部１０は複数の速度検知結果から速度折返しの有無を判定し、物標の正しい速度を計算する部分である。方位推定部１１は物標の方位を計算する部分であり、複数の受信信号の位相情報列から物標の方位角度を求める。 The frequency control unit 6 controls the center frequency of the chirp signal. The signal processing unit 7 includes a distance / speed detection unit 9, a turn-back correction speed calculation unit 10, and an azimuth estimation unit 11. The distance / speed detection unit 9 includes a circuit that performs FFT processing from the received signal input from the analog unit 2. The turn-back correction speed calculation unit 10 is a part that determines the presence or absence of speed turn-back from a plurality of speed detection results and calculates the correct speed of the target. The azimuth estimation unit 11 is a part for calculating the azimuth of the target, and obtains the azimuth angle of the target from the phase information sequences of a plurality of received signals.
　レーダ装置１は検知した距離情報、速度情報、方位角度情報を物標検知情報として出力する。 The radar device 1 outputs the detected distance information, speed information, and azimuth angle information as target detection information.
　［アナログ部］
  図４にアナログ部２の構成の詳細を示す。アナログ部２は送信部４と受信部５からなる。送信部４はシンセサイザ４１、アンプ４２、送信アンテナ４３を有する。シンセサイザ４１では後述する周波数制御部６で指定された中心周波数のチャープ信号が生成される。
この信号はアンプ４２を通じて増幅され送信アンテナ４３から送信信号として送信される。送信信号は物標で反射され、反射波となる。 [Analog section]
FIG. 4 shows the details of the configuration of the analog unit 2. The analog unit 2 includes a transmission unit 4 and a reception unit 5. The transmission unit 4 has a synthesizer 41, an amplifier 42, and a transmission antenna 43. The synthesizer 41 generates a chirp signal having a center frequency specified by the frequency control unit 6 described later.
This signal is amplified through the amplifier 42 and transmitted as a transmission signal from the transmission antenna 43. The transmitted signal is reflected by the target and becomes a reflected wave.
　受信部５は複数の受信アンテナ５１、各アンテナのアンプ５２、ミキサ５３、フィルタ５４、およびＡ／Ｄ変換器５５を有する。受信アンテナ５１では送信信号が物標で反射された反射波を受信する。受信アンテナ５１で受信した信号はアンプ５２で増幅され、ミキサ５３へ出力する。ミキサ５３は送信部４から送信信号を受け取り、受信アンテナ５１から入力される受信信号をミキシングすることでビート信号を生成し、Ａ／Ｄ変換機５５へ出力する。物標までの距離に応じて送信信号の周波数と受信信号の周波数には差があり、ビート信号は送信信号の周波数と受信信号の周波数の差となる周波数を有する。 The receiving unit 5 has a plurality of receiving antennas 51, an amplifier 52 for each antenna, a mixer 53, a filter 54, and an A / D converter 55. The receiving antenna 51 receives the reflected wave whose transmission signal is reflected by the target. The signal received by the receiving antenna 51 is amplified by the amplifier 52 and output to the mixer 53. The mixer 53 receives a transmission signal from the transmission unit 4, mixes the reception signal input from the reception antenna 51 to generate a beat signal, and outputs the beat signal to the A / D converter 55. There is a difference between the frequency of the transmission signal and the frequency of the reception signal depending on the distance to the target, and the beat signal has a frequency that is the difference between the frequency of the transmission signal and the frequency of the reception signal.
　［デジタル部］
  デジタル部３は周波数制御部６と信号処理部７と記憶部８とを有する。周波数制御部６は図２に示すような第一変調波と第二変調波を含むチャープ信号の変調帯域幅、中心周波数、チャープ周期を制御する。 [Digital section]
The digital unit 3 has a frequency control unit 6, a signal processing unit 7, and a storage unit 8. The frequency control unit 6 controls the modulation bandwidth, center frequency, and chirp period of the chirp signal including the first modulated wave and the second modulated wave as shown in FIG.
　本実施例にかかるレーダ装置の周波数制御部は第一変調方式で変調したチャープ波と第二変調方式で変調したチャープ波を交互に送信する。第一変調方式は変調帯域幅Ｂ１、中心周波数ｆ１、チャープ周期ｔ１のチャープ波であり、第二変調方式は変調帯域幅Ｂ２、中心周波数ｆ２、チャープ周期ｔ２のチャープ波である。チャープ周期ｔ１とチャープ周期ｔ２は略同一である。第一変調方式と第二変調方式の帯域幅Ｂ１、Ｂ２は等しいことが望ましいが、Ｂ１とＢ２の差が帯域幅／（チャープ内サンプル数×２）以下であればよく、装置等に起因する多少の誤差を含んでも良いことは言うまでもない。 The frequency control unit of the radar device according to this embodiment alternately transmits the chirp wave modulated by the first modulation method and the chirp wave modulated by the second modulation method. The first modulation method is a chirp wave having a modulation bandwidth B1, a center frequency f1, and a chirp period t1, and the second modulation method is a chirp wave having a modulation bandwidth B2, a center frequency f2, and a chirp period t2. The chirp period t1 and the chirp period t2 are substantially the same. It is desirable that the bandwidths B1 and B2 of the first modulation method and the second modulation method are equal, but the difference between B1 and B2 may be the bandwidth / (number of samples in chirp × 2) or less, which is caused by the device or the like. Needless to say, some errors may be included.
　詳細は後に説明するが、距離、速度を算出するために、ＦＦＴ後に第一変調波による検知距離、速度と第二変調波による検知距離、速度の結び付けを行う。ここで、第一変調波の最大検知距離Ｒ１ｍａｘと第二変調波の最大検知距離Ｒ２ｍａｘの差が距離分解能の１／２以上の場合、二つの結果を結び付けることが難しくなる。そのため、Ｂ１とＢ２の差は帯域幅／（チャープ内サンプル数×２）以下が良い。 Details will be explained later, but in order to calculate the distance and speed, the detection distance by the first modulated wave, the speed and the detection distance by the second modulated wave, and the speed are linked after the FFT. Here, when the difference between the maximum detection distance R1max of the first modulated wave and the maximum detection distance R2max of the second modulated wave is ½ or more of the distance resolution, it becomes difficult to connect the two results. Therefore, the difference between B1 and B2 should be bandwidth / (number of samples in chirp × 2) or less.
　例えば、チャープ内サンプル数が１０２４、変調帯域が１５００ＭＨｚの場合、１５００／（１０２４・２）＝０．７３ ＭＨｚの帯域誤差があると、最大検知距離の誤差が距離分解能の１／２となり、第一変調波による検知結果と第二変調波による検知結果の結び付けが難しくなる。したがってこの場合は０．７３ＭＨｚ以下の帯域誤差であることが望ましい。 For example, when the number of samples in the chirp is 1024 and the modulation band is 1500 MHz, if there is a band error of 1500 / (1024.2) = 0.73 MHz, the error of the maximum detection distance becomes 1/2 of the distance resolution, and the second It becomes difficult to connect the detection result of the first modulated wave and the detection result of the second modulated wave. Therefore, in this case, it is desirable that the band error is 0.73 MHz or less.
　また、第一変調波と第二変調波の使用帯域が重なると、変調帯域内で速度折返しと角度折返しの不確定性が生じる場合がある。そのため、第一変調波の中心周波数ｆ１と第二変調波の中心周波数ｆ２は少なくとも変調帯域幅Ｂだけ離した方が良い。第一変調波の中心周波数ｆ１と第二変調波の中心周波数ｆ２の差、すなわち中心周波数の偏差を変調帯域幅以上にすることにより、第一変調波と第二変調波の使用周波数帯域が独立する。 Further, when the used bands of the first modulated wave and the second modulated wave overlap, the uncertainty of velocity folding and angle folding may occur in the modulation band. Therefore, it is better that the center frequency f1 of the first modulated wave and the center frequency f2 of the second modulated wave are separated by at least the modulation bandwidth B. By making the difference between the center frequency f1 of the first modulated wave and the center frequency f2 of the second modulated wave, that is, the deviation of the center frequency equal to or larger than the modulation bandwidth, the frequency bands used by the first modulated wave and the second modulated wave become independent. do.
　チャープ周期ｔ１、ｔ２は第一変調波と第二変調波で最大検知速度Ｖ１ｍａｘ、Ｖ２ｍａｘが等しくならないような値である必要がある。第一変調波の最大検知速度Ｖ１ｍａｘは第一変調波の波長λ１と第一変調波のチャープ周期ｔ１を用いてＶ１ｍａｘ＝λ１／（４・ｔ１）と示され、第二変調波の最大検知速度Ｖ２ｍａｘは第二変調波の波長λ２と第二変調波のチャープ周期ｔ２を用いてＶ２ｍａｘ＝λ２／（４・ｔ２）と示されるため、ｔ１／ｔ２≠λ１／λ２でなければならない。 The chirp periods t1 and t2 need to be values such that the maximum detection speeds V1max and V2max are not equal between the first modulated wave and the second modulated wave. The maximum detection speed V1max of the first modulated wave is shown as V1max = λ1 / (4 · t1) using the wavelength λ1 of the first modulated wave and the charm period t1 of the first modulated wave, and the maximum detection speed of the second modulated wave. Since V2max is shown as V2max = λ2 / (4 · t2) using the wavelength λ2 of the second modulated wave and the charp period t2 of the second modulated wave, t1 / t2 ≠ λ1 / λ2.
　また、チャープ周期ｔ１、ｔ２と第一変調波と第二変調波のチャープ数Ｎ１、Ｎ２は第一変調波の速度分解能Ｖ１ｒｅｓ＝λ１／（２・Ｎ１・ｔ１）と第二変調波の速度分解能Ｖ２ｒｅｓ＝λ２／（２・Ｎ２・ｔ２）が等しくなるような値であることが望ましいが、速度折返し処理可能な最大検知速度に近い速度において、第一変調波による検知速度ｂｉｎと第二変調波による検知速度ｂｉｎの差が速度分解能の半分未満となればよく、チャープ周期ｔ１、ｔ２において装置等に起因する多少の誤差を含んでも良い。 Further, the chirp periods t1 and t2 and the chirp numbers N1 and N2 of the first modulated wave and the second modulated wave are the speed resolution of the first modulated wave V1res = λ1 / (2 ・ N1 ・ t1) and the speed resolution of the second modulated wave. It is desirable that V2res = λ2 / (2, N2, t2) be equal, but at a speed close to the maximum detection speed that can be speed-folded, the detection speed bin and the second modulation wave by the first modulation wave It is sufficient that the difference in the detection speed bin due to the above is less than half of the speed resolution, and some errors due to the device or the like may be included in the chirp cycles t1 and t2.
　信号処理部７は距離速度検出部９と折返し補正速度算出部１０と方位推定部１１とを有する。距離速度検出部９には、受信部５から第一変調波の受信信号が入力される。距離速度検出部９では第一位変調波の受信信号に対して時間周波数ＦＦＴを行い、ＦＦＴ処理後の信号を得る。ＦＦＴ処理により距離・速度のパワースペクトルが得られる。ここで得られる距離・速度のパワースペクトルに基づいて、距離ｂｉｎおよび速度ｂｉｎから距離Ｒ１および速度Ｖ１を選択し、距離Ｒ１および速度Ｖ１をメモリ部８に伝送する。この処理を各受信アンテナの受信信号に対し同様に行う。 The signal processing unit 7 has a distance speed detection unit 9, a turn-back correction speed calculation unit 10, and an azimuth estimation unit 11. The reception signal of the first modulated wave is input from the reception unit 5 to the distance velocity detection unit 9. The distance velocity detection unit 9 performs a time frequency FFT on the received signal of the first-order modulated wave, and obtains a signal after FFT processing. The power spectrum of distance and velocity can be obtained by FFT processing. Based on the distance / velocity power spectrum obtained here, the distance R1 and the velocity V1 are selected from the distance bin and the velocity bin, and the distance R1 and the velocity V1 are transmitted to the memory unit 8. This process is similarly performed for the received signal of each receiving antenna.
　また、ＦＦＴ処理により距離・速度スペクトルを求める際、各受信アンテナの受信信号の位相を表す複素情報が得られる。距離速度検出部９では第一変調波の受信信号の位相情報列ａ１もメモリ部に伝送する。 Further, when the distance / velocity spectrum is obtained by FFT processing, complex information indicating the phase of the received signal of each receiving antenna can be obtained. The distance velocity detection unit 9 also transmits the phase information sequence a1 of the received signal of the first modulated wave to the memory unit.
　次に距離速度検出部９には受信部５から第二変調波の受信信号が入力される。距離速度検出部９では第一変調波に対する処理と同様に時間周波数ＦＦＴを行うことで距離Ｒ２および速度Ｖ２を算出し、距離Ｒ２および速度Ｖ２と対応する位相情報列ａ２をメモリ部に伝送するＦＦＴの結果により物標までの距離Ｒを確定する。第一変調波と第二変調波のそれぞれの反射波から速度を求める際に必要な最大検知速度は、周波数制御部から中心周波数ｆ１、ｆ２を受け取ることで確定する。 Next, the received signal of the second modulated wave is input from the receiving unit 5 to the distance velocity detecting unit 9. The distance velocity detection unit 9 calculates the distance R2 and the velocity V2 by performing the time frequency FFT in the same manner as the processing for the first modulated wave, and transmits the phase information sequence a2 corresponding to the distance R2 and the velocity V2 to the memory unit. The distance R to the target is determined by the result of. The maximum detection speed required to obtain the speed from the reflected waves of the first modulated wave and the second modulated wave is determined by receiving the center frequencies f1 and f2 from the frequency control unit.
　折返し補正速度算出部１０では、メモリ部８に保存されている第一変調波から算出した速度Ｖ１と第二変調波から算出した速度Ｖ２を読み込む。Ｖ１とＶ２が一致している場合、物標の相対速度ＶはＶ１（またはＶ２）と確定することができる。検知速度Ｖ１、Ｖ２が一致しない場合、最大検知速度に基づきＶ１、Ｖ２が何回折返した速度で一致するか計算する。具体的にはＶ１＋２・ｎ１・Ｖ１ｍａｘ＝Ｖ２＋２・ｎ２・Ｖ２ｍａｘを満たす整数ｎ１、ｎ２を求める。これを満たすｎ１、ｎ２の時の速度を物標の相対速度Ｖとして確定し、出力する。 The folding correction speed calculation unit 10 reads the speed V1 calculated from the first modulated wave and the speed V2 calculated from the second modulated wave stored in the memory unit 8. When V1 and V2 match, the relative velocity V of the target can be determined to be V1 (or V2). When the detection speeds V1 and V2 do not match, the speed at which V1 and V2 match is calculated based on the maximum detection speed. Specifically, integers n1 and n2 satisfying V1 + 2, n1, V1max = V2 + 2, n2, V2max are obtained. The velocities at n1 and n2 that satisfy this are determined as the relative velocities V of the target and output.
　図５は第一変調波と第二変調波で最大検知速度Ｖ１ｍａｘ、Ｖ２ｍａｘを超える速度で移動する同一の物標を検知した場合に距離速度検出部９で算出された距離、速度の一例を示している。第一変調波による物標検知において、検知した物標の正しい速度ｂｉｎはＶ１ａｃｔである。しかし、第一変調波の最大検知速度Ｖ１ｍａｘを超えているため距離速度検出部９で算出された速度ｂｉｎはＶ１ｅｓｔとなる。第二変調波による物標見地において、検知した物標の正しい速度ｂｉｎはＶ２ａｃtである。しかし、第二変調波の最大検知速度Ｖ２ｍａｘを超えているため距離速度検出部９で産出された速度ｂｉｎはＶ２ｅｓｔとなる。二つの速度Ｖ１ｅｓｔとＶ２ｅｓｔを比較すると検知速度が異なるため、速度検知結果が誤りであることがわかる。速度方向に１回折返したｂｉｎで二つの速度ｂｉｎが一致することから正しい速度ｂｉｎがＶ１ａｃｔ、Ｖ２ａｃｔであることがわかる。 FIG. 5 shows an example of the distance and speed calculated by the distance speed detection unit 9 when the same target moving at a speed exceeding the maximum detection speeds V1max and V2max is detected in the first modulated wave and the second modulated wave. ing. In the target detection by the first modulated wave, the correct velocity bin of the detected target is V1act. However, since the maximum detection speed V1max of the first modulated wave is exceeded, the speed bin calculated by the distance speed detection unit 9 is V1est. The correct velocity bin of the detected target is V2act in the targeting point by the second modulated wave. However, since the maximum detection speed V2max of the second modulated wave is exceeded, the speed bin produced by the distance speed detection unit 9 is V2est. Comparing the two speeds V1est and V2est shows that the speed detection results are incorrect because the detection speeds are different. It can be seen that the correct velocity bins are V1act and V2act because the two velocity bins match with the bin that is turned back once in the velocity direction.
　図６Ａは方位推定部１１の処理、すなわち中心周波数の異なる受信信号から得られる位相情報列を中心周波数に基づき補正、結合する処理の詳細を示している。 FIG. 6A shows the details of the processing of the direction estimation unit 11, that is, the processing of correcting and combining the phase information sequences obtained from the received signals having different center frequencies based on the center frequency.
　方位推定部１１は位相情報結合部１２と方位計算処理部１３からなる。位相情報結合部１２では、周波数制御部から第一変調波の中心周波数ｆ２と第二変調波の中心周波数ｆ２を読み込む。また、メモリ部８から第一変調波と第二変調波の各受信アンテナで受信した信号の位相情報列ａ１、ａ２を読み込む。中心周波数ｆ１、ｆ２に基づきアンテナ座標ｄを算出し、また、２つの位相情報列ａ１、ａ２を結合した位相情報列ａを算出し、アンテナ座標ｄおよび位相情報列ａを方位計算処理部１３に出力する。 The directional estimation unit 11 includes a phase information coupling unit 12 and a directional calculation processing unit 13. The phase information coupling unit 12 reads the center frequency f2 of the first modulated wave and the center frequency f2 of the second modulated wave from the frequency control unit. Further, the phase information sequences a1 and a2 of the signals received by the receiving antennas of the first modulated wave and the second modulated wave are read from the memory unit 8. The antenna coordinates d are calculated based on the center frequencies f1 and f2, the phase information sequence a obtained by combining the two phase information sequences a1 and a2 is calculated, and the antenna coordinates d and the phase information sequence a are sent to the direction calculation processing unit 13. Output.
　図６Ｂのフローチャートを参照して位相情報結合部１２の処理について説明する。位相情報結合部は、特定の受信アンテナでの受信信号で振幅、位相を規格化する。また、位相情報結合部は、中心周波数の異なる位相情報から、それぞれ方位角度を算出し、方位角度で生じる虚像を補正する。 The processing of the phase information coupling unit 12 will be described with reference to the flowchart of FIG. 6B. The phase information coupling unit normalizes the amplitude and phase of the received signal at a specific receiving antenna. Further, the phase information coupling unit calculates the directional angle from the phase information having different center frequencies, and corrects the virtual image generated by the directional angle.
　Ｓ１２１，Ｓ１２３では，周波数制御部から取得した中心周波数ｆ１、ｆ２に基づき、第一変調波の波長λ１、第二変調波の波長λ２を求める。 In S121 and S123, the wavelength λ1 of the first modulated wave and the wavelength λ2 of the second modulated wave are obtained based on the center frequencies f1 and f2 acquired from the frequency control unit.
　Ｓ１２２，Ｓ１２４では、第一変調波の波長λ１に対するアンテナ配置ｄ１と、第二変調波の波長λ２に対するアンテナ座標ｄ２を求める。具体的には、レーダ装置のアンテナ座標をλ１、λ２で除算することで求める。 In S122 and S124, the antenna arrangement d1 for the wavelength λ1 of the first modulated wave and the antenna coordinates d2 for the wavelength λ2 of the second modulated wave are obtained. Specifically, it is obtained by dividing the antenna coordinates of the radar device by λ1 and λ2.
　Ｓ１２５では、ｄ１の要素の一つの座標とそれに対応するｄ２の要素を一致させる。第一変調波と第二変調波の中心周波数を変えることによりアンテナ利得の偏差が生じる。ここで生じるアンテナ利得を補正するために1つのアンテナで規格化する必要がある。そのため、ｄ１の一要素とｄ２の一要素を共通化する。 In S125, one coordinate of the element of d1 and the corresponding element of d2 are matched. Deviation of antenna gain occurs by changing the center frequency of the first modulated wave and the second modulated wave. It is necessary to normalize with one antenna in order to correct the antenna gain generated here. Therefore, one element of d1 and one element of d2 are shared.
　Ｓ１２６では、アンテナ座標ｄ１とアンテナ座標ｄ１にあわせて規格化したアンテナ座標ｄ２を結合し、一つの座標列としたアンテナ配置ｄを生成する。 In S126, the antenna coordinates d1 and the antenna coordinates d2 standardized according to the antenna coordinates d1 are combined to generate the antenna arrangement d as one coordinate sequence.
　Ｓ１２７では、第二変調波の受信位相情報列ａ２を第一変調波の受信位相情報列ａ１にあわせて規格化する。このとき、位相情報列ａ１、ａ２のうち、Ｓ１２５で共通化したアンテナ座標に対応する要素に基づいて規格化を行う。 In S127, the received phase information string a2 of the second modulated wave is standardized according to the received phase information string a1 of the first modulated wave. At this time, standardization is performed based on the elements corresponding to the antenna coordinates common in S125 among the phase information sequences a1 and a2.
　Ｓ１２８では、位相情報列ａ１とａ２を結合し、一つの位相情報列としたａを生成する。 In S128, the phase information strings a1 and a2 are combined to generate a as one phase information sequence.
　図７は第一変調波の受信信号と第二変調波の受信信号のアンテナの座標を一番左のアンテナの座標を共通化した場合の受信アンテナ座標を示している。アンテナ座標６０１は上記アンテナ座標ｄ１を示し、アンテナ座標６０２は上記アンテナ座標ｄ２を示している。 FIG. 7 shows the receiving antenna coordinates when the coordinates of the antennas of the received signal of the first modulated wave and the received signal of the second modulated wave are shared with the coordinates of the leftmost antenna. The antenna coordinates 601 indicate the antenna coordinates d1, and the antenna coordinates 602 indicate the antenna coordinates d2.
　第一変調波による位相情報列ａ１は図７の第一変調波に対応するアンテナ座標６０１で受信したとみなされ、第二変調波による位相情報列ａ２は図７の第二変調波に対応するアンテナ座標６０２で受信したとみなされる。位相情報列ａ１の一番左のアンテナに対応する一要素と位相情報列ａ２の一番左のアンテナに対応する一要素が等しくなるように、位相情報列ａ２を規格化する。この処理により第一変調波の受信信号と第二変調波の受信信号を結合した座標列ｄと位相情報列ａを生成する。方位計算処理部１３では結合された座標列ｄと位相情報列ａを用いてＤＢＦやＣａｐｏｎなどの方位推定アルゴリズムにより物標の方位角度を算出する。算出した方位角度は物標検知情報としてレーダ装置から出力される。 The phase information sequence a1 by the first modulated wave is considered to have been received at the antenna coordinates 601 corresponding to the first modulated wave of FIG. 7, and the phase information sequence a2 by the second modulated wave corresponds to the second modulated wave of FIG. It is considered to have been received at antenna coordinates 602. The phase information sequence a2 is standardized so that one element corresponding to the leftmost antenna of the phase information sequence a1 and one element corresponding to the leftmost antenna of the phase information sequence a2 are equal. By this processing, the coordinate sequence d and the phase information sequence a in which the received signal of the first modulated wave and the received signal of the second modulated wave are combined are generated. The directional calculation processing unit 13 calculates the directional angle of the target by the directional estimation algorithm such as DBF or Capon using the combined coordinate sequence d and the phase information sequence a. The calculated azimuth angle is output from the radar device as target detection information.
　図７の例において送信するチャープ信号が第一変調波のみの場合には、方位推定に利用できる位相情報の要素数が１２個であるのに対し、本実施形態にかかるレーダ装置のように送信するチャープ信号が中心周波数の異なる第一変調波と第二変調をもつチャープ信号の場合には、方位推定に利用できる位相情報の要素数は２３個まで増加する。 In the example of FIG. 7, when the chirp signal to be transmitted is only the first modulated wave, the number of phase information elements that can be used for azimuth estimation is 12, whereas the chirp signal is transmitted as in the radar device according to the present embodiment. When the chirp signal to be used is a chirp signal having a first modulation wave and a second modulation having different center frequencies, the number of phase information elements that can be used for azimuth estimation increases to 23.
　［効果］
  以上説明した実施例１によれば、以下の効果が得られる。 [effect]
According to the first embodiment described above, the following effects can be obtained.
　（１）第一変調波のみでは最大検知速度がＶ１ｍａｘ、第二変調波のみでは最大検知速度がＶ２ｍａｘであるが、中心周波数の異なる第一変調波と第二編調波を用いることにより最大検知速度をＶ１ｍａｘとＶ２ｍａｘの最小公倍数まで拡大することができる。
また、従来技術であるチャープ周期の異なるチャープ波を送信することにより最大検知速度を延ばす手法では空送時間を多くとる必要があるが、本実施例では中心周波数を異ならせることで最大検知速度を異ならせているため、チャープ空送時間を短くすることができ、受信電力の減少を防ぐことが可能である。したがって、より遠方まで物標検知可能になる。 (1) The maximum detection speed is V1max only for the first modulated wave, and the maximum detection speed is V2max only for the second modulated wave, but the maximum detection is performed by using the first modulated wave and the second volume tuning wave having different center frequencies. The speed can be expanded to the least common multiple of V1max and V2max.
In addition, in the conventional method of extending the maximum detection speed by transmitting chirp waves with different chirp periods, it is necessary to take a large amount of idle feed time, but in this embodiment, the maximum detection speed is increased by changing the center frequency. Since the chirps are different, the chirp airborne time can be shortened and the reception power can be prevented from decreasing. Therefore, it becomes possible to detect a target farther.
　（２）波長の異なるチャープ波を用いることで物標の方位角度推定に使用できる位相情報を増やすことができる。受信アンテナ数がｋ本で周波数の異なる二つの変調波を使用した場合、方位推定に使用できる位相情報は２ｋ－１個となる。 (2) By using chirp waves with different wavelengths, it is possible to increase the phase information that can be used to estimate the azimuth angle of the target. When two modulated waves with k receiving antennas and different frequencies are used, the phase information that can be used for directional estimation is 2k-1.
　（３）波長の異なるチャープ波を用いることで、第一変調波の波長に対応するアンテナ/波長座標列ｄ１及び位相情報列ａ１と第二変調波の波長に対応するアンテナ/波長座標列ｄ２および位相情報列ａ２から結合したアンテナ/波長座標列ｄと位相情報列ａを正成することで、アンテナ素子の大きさよりも狭く物理的に配置不可能なアンテナ間隔の位相情報を得ることができる。 (3) By using charm waves having different wavelengths, the antenna / wavelength coordinate sequence d1 corresponding to the wavelength of the first modulated wave and the phase information sequence a1 and the antenna / wavelength coordinate sequence d2 corresponding to the wavelength of the second modulated wave and By positively forming the antenna / wavelength coordinate sequence d coupled from the phase information sequence a2 and the phase information sequence a, it is possible to obtain phase information of an antenna interval that is narrower than the size of the antenna element and cannot be physically arranged.
　本発明は上記した実施例に限定されるものではなく、様々な変形例が含まれる。 The present invention is not limited to the above-described embodiment, but includes various modifications.
　［変形例１］
  第一変調波の受信信号による方位推定と第二変調波の受信信号による方位推定を分けて二度の方位推定を行ってもよい。二度の方位推定を行う場合の処理を図８に示す。 [Modification 1]
The directional estimation based on the received signal of the first modulated wave and the directional estimation based on the received signal of the second modulated wave may be separately performed for the directional estimation twice. FIG. 8 shows the processing in the case of performing the direction estimation twice.
　第一変調波による方位推定を行う第一方位角度推定部１０１と第二変調波による第二方位推定部１０２と虚像除去部１０３とを有する。第一方位推定部１０１および第二方位推定部１０２では受信位相列を用いてＣａｐｏｎ等の高分解能方位角度推定処理を行う。 It has a first azimuth angle estimation unit 101 that estimates the direction by the first modulated wave, a second azimuth estimation unit 102 by the second modulated wave, and a virtual image removing unit 103. The first azimuth estimation unit 101 and the second azimuth estimation unit 102 perform high-resolution azimuth angle estimation processing such as Capon using the received phase sequence.
　虚像除去部１０３では第一方位推定部１０１で推定した物標方位と第二方位推定部１０２で推定した物標方位から物標の真の方位を推定する。角度折返しがない場合、第一変調波による方位角度推定結果と第二変調波による方位角度推定結果は一致する。第一方位推定部で推定した方位と第二方位推定部で推定した方位が一致している場合、第一方位推定部と第二方位推定部で検知した方位を真の物標方位として決定する。一方、角度折返しがある場合第一変調波による角度推定方位と第二変調波による角度推定方位が一致しない。
したがって第一方位推定部と第二方位推定部で異なる方位角度を算出した場合にはその物標を虚像として削除する。 The virtual image removing unit 103 estimates the true direction of the target from the target direction estimated by the first direction estimation unit 101 and the target direction estimated by the second direction estimation unit 102. If there is no angle turning, the directional angle estimation result by the first modulated wave and the directional angle estimation result by the second modulated wave match. If the direction estimated by the first direction estimation unit and the direction estimated by the second direction estimation unit match, the direction detected by the first direction estimation unit and the second direction estimation unit is determined as the true target direction. .. On the other hand, when there is angle folding, the angle estimation direction by the first modulated wave and the angle estimation direction by the second modulated wave do not match.
Therefore, when different azimuth angles are calculated by the first azimuth estimation unit and the second azimuth estimation unit, the target is deleted as a virtual image.
　図９は角度折返しによる虚像を検知した場合の方位推定の一例を示している。図９は真の物標方位が４５度の例である。すなわち図９の第一方位角度推定部で推定した物標方位のうち右のピークは正しい方位であり左のピークは角度折返しによる虚像を示している。
また、第二方位角度推定部で推定した物標方位のうち右のピークは正しい方位であり左のピークは角度折返しによる虚像を示している。 FIG. 9 shows an example of directional estimation when a virtual image due to angle folding is detected. FIG. 9 is an example in which the true target direction is 45 degrees. That is, of the target azimuths estimated by the first azimuth angle estimation unit in FIG. 9, the right peak is the correct azimuth and the left peak shows a virtual image due to angle folding.
Further, among the target azimuths estimated by the second azimuth angle estimation unit, the peak on the right is the correct azimuth and the peak on the left shows a virtual image due to angle folding.
　第一方位角度推定部と第二方位角度推定部の一方のみでは正しい物標方位のピークと虚像を判別することができない。しかし、虚像補正部で第一方位角度推定部と第二方位角度推定部の結果を比較することで右のピークが一致し、左のピークはずれが生じる。この結果より右のピークのみが正しい物標方位であると判定する。 The peak and virtual image of the correct target azimuth cannot be discriminated by only one of the first azimuth angle estimation unit and the second azimuth angle estimation unit. However, by comparing the results of the first azimuth angle estimation unit and the second azimuth angle estimation unit with the virtual image correction unit, the peaks on the right match and the peaks on the left deviate. From this result, it is determined that only the peak on the right is the correct target orientation.
　［変形例２］
  受信部において受信アンテナの間隔は不等間隔であってもよい。受信アンテナの間隔が不等間隔であっても上記で説明した処理と同様に距離、速度を求める。方位推定において、位相情報列ｄ１、ｄ２の要素が不等間隔になるが、方位推定の計算は同様である。 [Modification 2]
The intervals between the receiving antennas in the receiving unit may be unequal. Even if the intervals between the receiving antennas are unequal, the distance and speed are obtained in the same way as the process described above. In the directional estimation, the elements of the phase information sequences d1 and d2 are unequally spaced, but the calculation of the directional estimation is the same.
　［変形例３］
　送信するチャープ信号のチャープ周期ｔ１、ｔ２は一定でなく、不等間隔であってもよい。チャープ周期ｔ１、ｔ２を変化させながらチャープ信号を送信することで、より正確な速度折返し補正が可能になる。 [Modification 3]
The chirp periods t1 and t2 of the chirp signal to be transmitted are not constant and may be unequal intervals. By transmitting the chirp signal while changing the chirp periods t1 and t2, more accurate speed turnaround correction becomes possible.
１　レーダ装置
２　アナログ部
３　デジタル部
４　送信部
５　受信部
６　周波数制御部
７　信号処理部
８　メモリ部
９　距離・速度検出部
１０　折返し補正速度算出部
１１　方位推定部
１２　位相情報結合部
１３　方位計算処理部
１０１　第一方位推定部
１０２　第二方位推定部
１０３　虚像除去部
６０１　第一変調波アンテナ座標列
６０２　第二変調波アンテナ座標列 1 Radar device 2 Analog unit 3 Digital unit 4 Transmission unit 5 Reception unit 6 Frequency control unit 7 Signal processing unit 8 Memory unit 9 Distance / speed detection unit 10 Fold-back correction speed calculation unit 11 Direction estimation unit 12 Phase information coupling unit 13 Direction calculation Processing unit 101 First-direction estimation unit 102 Second-direction estimation unit 103 Void image removal unit 601 First modulation wave antenna coordinate sequence 602 Second modulation wave antenna coordinate sequence

Claims (9)

  1. レーダ装置であって、
    単一の送信アンテナから帯域幅が同一で中心周波数が異なる複数のチャープ波を時間的に交互に送信する送信部と、前記チャープ波による物標からの反射波を受信する複数の受信アンテナを備えた受信部と、中心周波数が異なる前記反射波からの受信信号それぞれに基づいて、前記物標の速度を検出し、前記速度の検出結果に基づき速度折返しを補正する速度算出部と、複数の前記受信アンテナで位相情報を取得し、取得した前記位相情報に基づき前記物標の方位角度を検出する方位推定部と、を備える、
    ことを特徴とするレーダ装置。     It ’s a radar device,
    It is equipped with a transmitter that alternately transmits a plurality of chirp waves having the same bandwidth but a different center frequency from a single transmitting antenna, and a plurality of receiving antennas that receive the reflected wave from the target by the chirp wave. A speed calculation unit that detects the speed of the target based on each of the receiving unit and the received signal from the reflected wave having a different center frequency and corrects the chirp based on the detection result of the speed, and a plurality of the above. A azimuth estimation unit that acquires phase information with a receiving antenna and detects the azimuth angle of the target based on the acquired phase information.
    A radar device characterized by that.
  2. 請求項１に記載のレーダ装置であって、
    前記中心周波数の偏差が前記帯域幅より大きい、
    ことを特徴とするレーダ装置。     The radar device according to claim 1.
    The deviation of the center frequency is larger than the bandwidth,
    A radar device characterized by that.
  3. 請求項１に記載のレーダ装置であって、
    前記方位推定部は、中心周波数の異なる前記受信信号から得られる位相情報列を中心周波数に基づき補正、結合する位相情報結合部と、結合した前記位相情報列を用いて方位計算を行う方位計算処理部を有する、
    ことを特徴とするレーダ装置。     The radar device according to claim 1.
    The azimuth estimation unit corrects and combines phase information sequences obtained from the received signals having different center frequencies based on the center frequency, and azimuth calculation processing that performs azimuth calculation using the combined phase information coupling unit and the combined phase information sequence. Have a part,
    A radar device characterized by that.
  4. 請求項３に記載のレーダ装置であって、
    前記位相情報結合部は、特定の前記受信アンテナでの受信信号で振幅、位相を規格化する、
    ことを特徴とするレーダ装置。     The radar device according to claim 3.
    The phase information coupling unit normalizes the amplitude and phase of the received signal at the specific receiving antenna.
    A radar device characterized by that.
  5. 請求項３に記載のレーダ装置であって、
    前記位相情報結合部は、前記中心周波数の異なる位相情報列から、それぞれ方位角度を算出し、前記方位角度で生じる虚像を補正する、
    ことを特徴とするレーダ装置。     The radar device according to claim 3.
    The phase information coupling unit calculates an azimuth angle from each of the phase information sequences having different center frequencies, and corrects a virtual image generated at the azimuth angle.
    A radar device characterized by that.
  6. 請求項３に記載のレーダ装置であって、
    前記中心周波数の偏差が前記帯域幅より大きい、
    ことを特徴とするレーダ装置。     The radar device according to claim 3.
    The deviation of the center frequency is larger than the bandwidth,
    A radar device characterized by that.
  7. 請求項３に記載のレーダ装置であって、
    複数の前記受信アンテナのアンテナ間隔が不等間隔である、
    ことを特徴とするレーダ装置。     The radar device according to claim 3.
    The antenna spacing of the plurality of receiving antennas is unequal.
    A radar device characterized by that.
  8. 請求項３に記載のレーダ装置であって、
    複数の前記チャープ波のチャープ周期が略同一である、
    ことを特徴とするレーダ装置。     The radar device according to claim 3.
    The chirp periods of the plurality of chirp waves are substantially the same,
    A radar device characterized by that.
  9. 請求項８に記載のレーダ装置であって、
    前記チャープ波の時間周期が不等間隔である、
    ことを特徴とするレーダ装置。     The radar device according to claim 8.
    The time period of the chirp wave is unequal.
    A radar device characterized by that.
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