WO2020022468A1 - Dispositif radar à ouverture synthétique, dispositif de traitement de signal radar à ouverture synthétique, programme de traitement de signal radar à ouverture synthétique et procédé d'observation radar à ouverture synthétique - Google Patents

Dispositif radar à ouverture synthétique, dispositif de traitement de signal radar à ouverture synthétique, programme de traitement de signal radar à ouverture synthétique et procédé d'observation radar à ouverture synthétique Download PDF

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Publication number
WO2020022468A1
WO2020022468A1 PCT/JP2019/029355 JP2019029355W WO2020022468A1 WO 2020022468 A1 WO2020022468 A1 WO 2020022468A1 JP 2019029355 W JP2019029355 W JP 2019029355W WO 2020022468 A1 WO2020022468 A1 WO 2020022468A1
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Prior art keywords
synthetic aperture
aperture radar
chirp pulse
azimuth
reflected
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PCT/JP2019/029355
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English (en)
Japanese (ja)
Inventor
貴宏 後藤
對馬　肩吾
スマンティヨ、ヨサファット、テトォコ スリ
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国立大学法人千葉大学
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Publication of WO2020022468A1 publication Critical patent/WO2020022468A1/fr

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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
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • G01S13/904—SAR modes
    • 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
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques

Definitions

  • the present disclosure relates to a synthetic aperture radar technology that achieves both high signal-to-noise ratio and high resolution.
  • Patent Literatures 1 to 3 and Non-Patent Literature 1 disclose methods for achieving both high signal-to-noise ratio and high resolution in the synthetic aperture radar technology.
  • a chirp pulse is emitted in a random direction to expand the observation range in the spotlight mode.
  • a chirp pulse is scanned in the range direction and the azimuth direction to realize Scan-SAR, TOPS-SAR, and the like.
  • a mechanical or electrical mechanism for controlling the direction of the irradiation beam is required to intentionally change the direction of the irradiation beam, a circuit is required. It becomes complicated and the system becomes expensive.
  • the present disclosure does not require a mechanical or electrical mechanism for controlling the direction of an irradiation beam while achieving both a high signal-to-noise ratio and high resolution in a synthetic aperture radar technology. It is an object of the present invention to simplify the circuit and reduce the cost of the system.
  • the present disclosure relates to a chirp pulse generation unit that generates a chirp pulse for range compression of a synthetic aperture radar, and a mechanical and electronic pointing device for irradiating the chirp pulse generated by the chirp pulse generation unit.
  • An antenna unit that changes the direction of the irradiation beam in the azimuth direction according to the frequency of the irradiation beam according to the inherent directional characteristic without performing control, a reflection signal receiving unit that receives a reflection signal reflected from the target,
  • a synthetic aperture radar apparatus comprising:
  • the present disclosure also provides a chirp pulse generation unit that generates a chirp pulse for range compression of a synthetic aperture radar, and irradiates the chirp pulse generated by the chirp pulse generation unit according to an inherent directional characteristic.
  • a synthetic aperture radar device comprising: an antenna unit that changes a beam direction in an azimuth direction according to a frequency of an irradiation beam; and a reflected signal receiving unit that receives a reflected signal reflected from a target.
  • the present disclosure also provides a chirp pulse generation procedure for generating a chirp pulse for range compression of a synthetic aperture radar, and a chirp pulse generation procedure for irradiating the antenna section according to a directional characteristic originally provided in the antenna section.
  • This is a characteristic synthetic aperture radar observation method.
  • the beam tilt generated by the directional characteristics of the antenna is positively used, so that the observable azimuth time becomes longer at any observation target position. Therefore, even if an attempt is made to increase the antenna gain, that is, to increase the aperture length in order to realize a high signal-to-noise ratio, the azimuth resolution can be prevented from being reduced by the synthetic aperture.
  • the direction of the irradiation beam is changed in the azimuth direction according to the frequency of the irradiation beam according to the inherent directional characteristics without performing the mechanical and electronic pointing control, the circuit is simplified and the system is inexpensive. Can be realized.
  • the chirp pulse generation unit controls the center frequency for each azimuth position to generate a chirp pulse, so that the azimuth direction of the irradiation beam irradiated by the antenna unit is directed to an observation area having a certain azimuth direction. And performing a synthetic aperture radar observation using a spotlight mode.
  • the chirp pulse generation unit generates a chirp pulse having a shape independent of the azimuth position, thereby changing the direction of the irradiation beam in the azimuth direction and not changing the direction of the irradiation beam in the azimuth direction.
  • a synthetic aperture radar apparatus characterized in that a synthetic aperture radar observation is performed using a strip mode in which the observable azimuth time is longer than in the past.
  • the chirp pulse generation unit may generate a chirp pulse having a shape independent of an azimuth position and having a center frequency such that squint in an azimuth direction of an irradiation beam irradiated by the antenna unit occurs. It is now possible to perform synthetic aperture radar observation using the squint mode, in which the observable azimuth time is longer than when the irradiation beam direction is changed in the azimuth direction and the irradiation beam direction is not changed in the azimuth direction. It is a synthetic aperture radar device characterized by the following.
  • the present disclosure is a reflection signal received by the reflection signal receiving unit of the synthetic aperture radar device described above, of the chirp pulse generated by the chirp pulse generation unit, is reflected from the observation target position for each azimuth position
  • a synthetic aperture radar signal processing apparatus characterized by performing a correlation process between a reference signal that selects only a partial section expected to be used.
  • the present disclosure is a reflection signal received by the reflection signal receiving unit of the synthetic aperture radar device described above, of the chirp pulse generated by the chirp pulse generation unit, is reflected from the observation target position for each azimuth position
  • This is a synthetic aperture radar signal processing program for causing a computer to execute a correlation process between a reference signal in which only a partial section expected to be selected is selected.
  • the receivable range time is shorter than in the related art, but the receivable azimuth time is longer, so that the total receivable time does not decrease. Therefore, even if an attempt is made to increase the bandwidth of the chirped pulse in order to realize a higher range resolution, it is possible to prevent the signal-to-noise ratio from being reduced by the beam tilt.
  • the reflection signal reflected from the observation target position, of the chirp pulse generated by the chirp pulse generation unit only a partial section expected to be reflected from the observation target position for each azimuth position And performing a correlation process in a time domain between the reference signal and the selected reference signal.
  • the reflection signal reflected from the observation target position, of the chirp pulse generated by the chirp pulse generation unit only a partial section expected to be reflected from the observation target position for each azimuth position Is a synthetic aperture radar signal processing program for causing a computer to execute a correlation process in a time domain between the selected reference signal and a reference signal.
  • the receivable range time is shorter than in the related art, but the receivable azimuth time is longer, so that the total receivable time does not decrease. Therefore, even if an attempt is made to increase the bandwidth of the chirped pulse in order to realize a higher range resolution, it is possible to prevent the signal-to-noise ratio from being reduced by the beam tilt. Further, although the calculation time is long, the image accuracy is high.
  • the present disclosure eliminates the need for a mechanical or electrical mechanism for controlling the direction of an irradiation beam while achieving a high signal-to-noise ratio and high resolution in a synthetic aperture radar technology, and simplifies the circuit. In addition, the cost of the system can be reduced.
  • FIG. 4 is a diagram illustrating a chirped pulse waveform and antenna directivity according to the present disclosure.
  • FIG. 3 is a diagram illustrating a configuration diagram of a spotlight mode according to the related art.
  • FIG. 3 is a diagram illustrating a strip mode of the present disclosure.
  • FIG. 3 is a diagram illustrating a score mode according to the present disclosure.
  • 1 is a diagram illustrating a configuration of a synthetic aperture radar system according to the present disclosure.
  • FIG. 3 is a diagram illustrating processing of the synthetic aperture radar system according to the present disclosure.
  • FIG. 5 is a diagram illustrating frequency characteristics of antenna directivity according to the present disclosure.
  • FIG. 5 is a diagram illustrating frequency characteristics of antenna directivity according to the present disclosure.
  • FIG. 5 is a diagram illustrating frequency characteristics of antenna directivity according to the present disclosure.
  • FIG. 4 is a diagram illustrating a time change of a chirp frequency according to the present disclosure.
  • FIG. 4 is a diagram illustrating a time change of the antenna directivity according to the present disclosure.
  • FIG. 3 is a diagram illustrating definitions of a direction and a distance of a target according to the present disclosure.
  • FIG. 4 is an explanatory diagram of an azimuth time during which a reflected signal of the present disclosure exists.
  • FIG. 4 is an explanatory diagram of a range time in which a chirp pulse according to the present disclosure is irradiated toward a target.
  • FIG. 4 is a diagram illustrating a reflection signal and a reference signal according to the present disclosure.
  • FIG. 4 is a diagram illustrating a point extension function of the present disclosure versus a distance in a range direction from a target.
  • FIG. 4 is a diagram illustrating a point extension function of the present disclosure versus an azimuth distance from a target.
  • FIG. 1 shows a chirp pulse waveform and antenna directivity according to the present disclosure.
  • beam tilt caused by the directional characteristics of the antenna is positively used. That is, in irradiating the chirp pulse, the direction of the irradiation beam is changed in the azimuth direction according to the frequency of the irradiation beam according to the inherent directional characteristic without performing the mechanical and electronic pointing control.
  • the chirp pulse sweeps the frequency from the minimum frequency f 0 -B W / 2 to the maximum frequency f 0 + B W / 2 via the center frequency f 0 over the range time 0 ⁇ ⁇ ⁇ ⁇ 0. .
  • an array antenna and a slot antenna are applied as the antenna unit A.
  • Each antenna element of the antenna section A is arranged in the azimuth direction x.
  • each antenna element of the antenna section A is excited in phase, and the irradiation beam of the antenna section A is directed in the front direction y.
  • the chirp pulse sweeps the minimum frequency f 0 -B W / 2
  • each antenna element of the antenna section A is not excited in phase, and the irradiation beam of the antenna section A is shifted in the direction ⁇ min shifted from the front direction y. ⁇ 0.
  • the chirp pulse sweeps the maximum frequency f 0 + B W / 2
  • the respective antenna elements of the antenna section A are not excited in phase, and the irradiation beam of the antenna section A has a direction ⁇ max> 0 shifted from the front direction y.
  • the direction ⁇ of the irradiation beam is changed in the azimuth direction x according to the frequency f of the irradiation beam according to the inherent directional characteristic without performing the mechanical and electronic pointing control. Let it.
  • FIG. 2 shows a configuration diagram of the spotlight mode of the prior art.
  • a chirp pulse having a shape not depending on the azimuth position x is generated, and the antenna control unit 13 (connected by a rotary joint or the like) mechanically directs the beam to thereby control the irradiation beam emitted by the antenna unit A.
  • the azimuth direction x is directed to a certain observation area, and the synthetic aperture radar observation is performed using the spotlight mode.
  • a chirp pulse having a shape not depending on the azimuth position x is generated, and the azimuth of the irradiation beam irradiated by the antenna unit A is controlled electronically by the phase shifter and the distributor of the antenna unit A.
  • the synthetic aperture radar observation is performed using the spotlight mode so that the direction x is directed to a certain observation area.
  • FIG. 5 shows a configuration diagram of the spotlight mode of the present disclosure.
  • the azimuth direction of the irradiation beam radiated by the antenna unit A according to the original directional characteristics without performing mechanical and electronic directional control.
  • x is directed to a certain observation area, and the synthetic aperture radar observation is performed using the spotlight mode.
  • FIG. 5 is also applicable to both the strip mode and the squint mode.
  • FIG. 3 shows the strip mode of the present disclosure.
  • the direction of the irradiation beam is changed in the azimuth direction x, and the observable azimuth time is shorter than when the direction of the irradiation beam is not changed in the azimuth direction x.
  • Synthetic aperture radar observation is performed using the strip mode in which is longer.
  • FIG. 3 shows a strip mode when there is no beam tilt according to the related art.
  • the synthetic aperture radar system S is located at the azimuth direction position x st, i and the chirp pulse sweeps the frequency f 0 ⁇ B W / 2 to f 0 + B W / 2, the target T is captured. Is starting to be.
  • the synthetic aperture radar system S is located at the azimuth direction position x st, f and the chirp pulse sweeps the frequency f 0 ⁇ B W / 2 to f 0 + B W / 2
  • the target T is: The capture range is over.
  • the azimuth direction range x st, i to x st, f is shorter than in the case of the present disclosure described later, the observable azimuth time is shorter than in the case of the present disclosure described later, and the azimuth resolution is the same as that of the present disclosure described later. It is lower than the case of disclosure.
  • FIG. 3 shows a strip mode when there is a beam tilt according to the present disclosure.
  • the synthetic aperture radar system S is located at the azimuth direction position x ' st, i and the chirp pulse sweeps the frequency f 0 -B W / 2, the target T has begun to be captured.
  • the azimuth direction position x'st, i is behind the azimuth direction position xst, i
  • the azimuth direction position x'st, f is ahead of the azimuth direction position xst, f . Therefore, since the azimuth direction range x ′ st, i to x ′ st, f is longer than that of the related art, the observable azimuth time is longer than that of the related art, and the azimuth resolution is higher than that of the related art.
  • FIG. 4 shows the scint mode of the present disclosure.
  • the center frequency is changed from f 0 in FIGS. 1 and 3 to f 0 ′ in FIG. 4 (however, in the case of FIG. 4, f 0 ′ ⁇ f 0 ). And shift.
  • the center frequency is changed from f 0 in FIGS. 1 and 3 to f 0 ′ in FIG. 4 (however, in FIG. 4, f 0 ′> f 0 ). And shift.
  • FIG. 4 shows a squint mode when there is no beam tilt according to the related art.
  • the synthetic aperture radar system S is located at the position x sq, i in the azimuth direction and the chirp pulse sweeps the frequencies f 0 ′ ⁇ B W / 2 to f 0 ′ + B W / 2, the target T is , Has begun to be caught.
  • the synthetic aperture radar system S is located at the azimuth position x sq, f and the chirp pulse sweeps the frequency f 0 ′ ⁇ B W / 2 to f 0 ′ + B W / 2, the target T Has been captured.
  • the azimuth direction range x sq, i to x sq, f is shorter than in the case of the present disclosure described later, so that the observable azimuth time is shorter than in the case of the present disclosure described later, and the azimuth resolution is defined in the following description. It is lower than the case of disclosure.
  • FIG. 4 shows a squint mode when there is a beam tilt according to the present disclosure.
  • the synthetic aperture radar system S is located at the azimuth position x ′ sq, i and the chirp pulse sweeps the frequency f 0 ′ ⁇ B W / 2, the target T has begun to be captured.
  • the synthetic aperture radar system S is located at the azimuth position x ′ sq, f and the chirp pulse sweeps the frequency f 0 ′ + B W / 2, the target T has been captured. .
  • the azimuth direction position x ' sq, i is behind the azimuth direction position x sq, i
  • the azimuth direction position x' sq, f is ahead of the azimuth direction position x sq, f . Therefore, since the azimuth direction range x ′ sq, i to x ′ sq, f is longer than that of the related art, the observable azimuth time is longer than that of the related art, and the azimuth resolution is higher than that of the related art.
  • FIG. 5 shows the configuration of the synthetic aperture radar system according to the present disclosure.
  • FIG. 6 shows the processing of the synthetic aperture radar system of the present disclosure.
  • the synthetic aperture radar system S includes a synthetic aperture radar device 1 and a synthetic aperture radar signal processing device 2.
  • the synthetic aperture radar device 1 includes a chirp pulse generating unit 11, an antenna unit A, and a reflected signal receiving unit 12, and is mounted on an artificial satellite or an aircraft.
  • the synthetic aperture radar signal processing device 2 includes a correlation processing execution unit 21, is mounted on an artificial satellite, an aircraft, a ground facility, or the like, and installs a synthetic aperture radar signal processing program shown in the lower section of FIG. 6 in a computer. Is realized by:
  • the synthetic aperture radar device 1 actively uses the beam tilt caused by the directional characteristics of the antenna.
  • the synthetic aperture radar apparatus 1 does not perform the mechanical and electronic pointing control but changes the direction ⁇ of the irradiation beam according to the frequency f of the irradiation beam according to the inherent directional characteristics. It is changed in the azimuth direction x.
  • the chirp pulse generation unit 11 generates a chirp pulse for range compression of the synthetic aperture radar (step S1).
  • the antenna unit A does not perform mechanical and electronic pointing control but changes the direction of the irradiation beam ⁇ according to the inherent directional characteristics. It is changed in the azimuth direction x according to f (step S2).
  • the reflected signal receiving unit 12 receives the reflected signal reflected from the target T by the antenna unit A (Step S3).
  • the synthetic aperture radar device 1 will be described with reference to FIGS. 7 to 10 are applied to the strip mode, but can be applied to both the spotlight and the squint modes by changing the center frequency.
  • the direction ⁇ of the irradiation beam is expressed by Expression 1 with respect to the frequency f of the irradiation beam.
  • the irradiation beam of the antenna unit A is directed in the direction ⁇ ⁇ 0 shifted from the front direction y.
  • the chirp pulse sweeps the frequency f 0 to f 0 + B W / 2
  • the irradiation beam of the antenna unit A is directed in the direction ⁇ > 0 shifted from the front direction y.
  • the irradiation beam half width of the antenna unit A is ⁇
  • the irradiation beam intensity of the antenna unit A is uniform within the irradiation beam width of the antenna unit A.
  • the irradiation beam intensity of the antenna unit A is assumed to be uniform within the irradiation beam width of the antenna unit A for simplicity, it is not uniform within the irradiation beam width of the antenna unit A as is practical. It may be.
  • FIG. 9 shows a time change of the chirp frequency according to the present disclosure.
  • the frequency f of the chirp pulse is expressed as shown in Expression 2 with respect to the range time ⁇ . Note that the time change of the chirp frequency may be rising to the right or falling to the right, and may not necessarily be a linear time change.
  • FIG. 10 shows a time change of the antenna directivity according to the present disclosure.
  • the direction ⁇ of the irradiation beam is expressed by Expression 3 with respect to the range time ⁇ . It should be noted that the time change of the antenna directivity may be rising to the right or falling to the right, and is not necessarily a linear time change.
  • the synthetic aperture radar signal processing device 2 refers to only a partial section of the chirp pulse irradiated toward the observation target position among the entire section of the chirp pulse irradiated at each azimuth time t as a reflected signal. It is taken into account in the correlation processing between the signals.
  • the correlation processing execution unit 21 performs a correlation process between the reflection signal and the reference signal (Step S11).
  • the synthetic aperture radar signal processing device 2 will be described with reference to FIGS. 11 to 14 are applied to the strip mode, but can be applied to both the spotlight and the squint modes by changing the center frequency.
  • the correlation processing execution unit 21 expects that the reflection signal received by the reflection signal reception unit 12 and the chirp pulse generated by the chirp pulse generation unit 11 are reflected from the observation target position for each azimuth position x. And a reference signal for which only a partial section is selected.
  • the correlation processing execution unit 21 is expected to reflect the reflection signal reflected from the observation target position and the chirp pulse generated by the chirp pulse generation unit 11 from the observation target position for each azimuth position x. Then, a correlation process in a time domain between the reference signal and the selected reference signal is performed. That is, in the present embodiment, the correlation processing execution unit 21 executes the correlation processing in the time domain between the reflected signal and the reference signal, so that the calculation time is long but the image accuracy is high.
  • the correlation processing execution unit 21 may execute the correlation processing in the frequency domain between the reflected signal and the reference signal, thereby significantly reducing the calculation time.
  • FIG. 11 shows the definitions of the direction and distance of the target of the present disclosure.
  • the position of the synthetic aperture radar system S is (x (t), 0), and the position of the target T is (X, Y).
  • the position x (t) in the azimuth direction of the synthetic aperture radar system S, the direction ⁇ (t) of the target T viewed from the synthetic aperture radar system S, and the distance R (t) from the synthetic aperture radar system S to the target T are expressed by the following equation (4). It is represented as Here, v is the speed of the synthetic aperture radar system S.
  • FIG. 12 is an explanatory diagram of the azimuth time at which the reflected signal of the present disclosure exists.
  • Equation 6 corresponds to the azimuth time t i in FIG. 14, and the right side of Equation 6 corresponds to the azimuth time t f in FIG.
  • the beam tilt generated by the directional characteristics of the antenna is positively used, so that the observable azimuth time t becomes longer at any observation target position. Therefore, even if an attempt is made to increase the antenna gain, that is, to increase the aperture length in order to realize a high signal-to-noise ratio, the azimuth resolution can be prevented from being reduced by the synthetic aperture. Further, in order to change the direction ⁇ of the irradiation beam in the azimuth direction x according to the frequency f of the irradiation beam according to the inherent directivity characteristic without performing the mechanical and electronic pointing control, the circuit is simplified and the system is changed. Can be realized at a low price.
  • FIG. 13 is an explanatory diagram of a range time in which the chirp pulse according to the present disclosure is irradiated toward the target T.
  • the range time ⁇ during which the target T can be observed at each azimuth time t is represented by Expression 7. That is, the direction ⁇ (t) of the target T viewed from the synthetic aperture radar system S only needs to satisfy the following condition: (1) The irradiation beam of the antenna unit A starts to turn toward the target T in the course of the chirp at the frequency f.
  • the direction ⁇ (t) is the same as the direction ⁇ ( ⁇ i (t)) + ⁇ of the outer edge of the irradiation beam of the antenna unit A, or the direction ⁇ (t) is ⁇ (0) ⁇ (2) the direction of the outer edge of the irradiation beam of the antenna section A when the irradiation beam of the antenna section A ends toward the target T in the course of the chirp of the frequency f ( ⁇ (0) + ⁇ ).
  • the direction ⁇ (t) is the same as compared to ⁇ f (t)) ⁇ ⁇ , or the direction ⁇ (t) is between ⁇ ( ⁇ 0 ) ⁇ and ⁇ ( ⁇ 0 ) + ⁇ .
  • Equation 8 corresponds to the range time ⁇ i (t) in FIGS. 13 and 14, and the right side of Equation 8 corresponds to the range time ⁇ f (t) in FIGS.
  • FIG. 14 shows the reflection signal and the reference signal of the present disclosure.
  • the reflection signal F (t, ⁇ ) reflected from the target T is represented by Expression 9.
  • the reference signal to be subjected to the correlation processing with the reflected signal F (t, ⁇ ) is determined based on the following theoretical formula of the reflected signal F (t, ⁇ ).
  • the value range of the azimuth time t of the reflection signal F (t, ⁇ ) is expressed by Expression 10 based on Expression 6.
  • the value range of the range time ⁇ of the reflected signal F (t, ⁇ ) is expressed by Expression 11 based on Expression 8 and the delay time of electromagnetic wave propagation.
  • the case where there is no beam tilt and the case where there is a beam tilt will be compared.
  • the range time range ⁇ if ⁇ ⁇ ⁇ ⁇ if + ⁇ 0 (where ⁇ if is the electromagnetic wave propagation Delay time) over the entire range time range ⁇ if ⁇ ⁇ ⁇ ⁇ if + ⁇ 0 and is considered in the correlation process between the reflected signal and the reference signal.
  • the synthetic aperture radar system S is closest azimuth time target T t c, Range Time Range ⁇ c ⁇ ⁇ ⁇ ⁇ c + ⁇ 0 ( however, tau c, a delay time of electromagnetic wave propagation.)
  • tau c a delay time of electromagnetic wave propagation.
  • the azimuth time width in which the reflected signal exists when there is no beam tilt and the azimuth time width in which the reflected signal exists when there is the beam tilt are displayed as having the same length.
  • the azimuth time width in which the reflected signal exists when there is no beam tilt is shorter than the azimuth time width in which the reflected signal exists when there is a beam tilt, and the reflection time when represented as shown in FIG.
  • the area of the signal is not larger when there is no beam tilt than when there is no beam tilt and when there is a beam tilt.
  • the synthetic aperture radar system S is closest azimuth time t c to the target T, among the range time range ⁇ c ⁇ ⁇ ⁇ ⁇ c + ⁇ 0, a part of the range time range max ⁇ i (t c) , ⁇ Only c ⁇ ⁇ ⁇ ⁇ min ⁇ ⁇ f (t c ), ⁇ c + ⁇ 0 ⁇ (see FIG. 13 and Equations 8 and 11) are considered in the correlation process between the reflected signal and the reference signal.
  • the azimuth time t f of the illumination beam of the antenna unit A finishes orientation target T, among the range time range ⁇ if ⁇ ⁇ ⁇ ⁇ if + ⁇ 0, a part of the range time range max ⁇ i (t f) , Only ⁇ if ⁇ ⁇ ⁇ ⁇ min ⁇ f (t f ), ⁇ if + ⁇ 0 ⁇ (see FIG. 13 and Equations 8, 11) are considered in the correlation process between the reflected signal and the reference signal.
  • the receivable range time ⁇ is shorter than in the related art, but the receivable azimuth time t is longer, so that the total receivable time is not reduced. Therefore, even if an attempt is made to increase the bandwidth of the chirped pulse in order to realize a higher range resolution, it is possible to prevent the signal-to-noise ratio from being reduced by the beam tilt.
  • a target P a reflection signal reflected from (X, Y) is F (X, Y) (t, ⁇ )
  • a reflection signal reflected from another target P ′ (X ′, Y ′) is F (X ′, Y ′) (t, ⁇ ).
  • the correlation S between the reflection signal F (X, Y) (t, ⁇ ) and the reflection signal F (X ′, Y ′) (t, ⁇ ) is expressed by Expression 12.
  • the correlation S is expected to take a large value if P: (X, Y) and P ′ :( X ′, Y ′) are close, and P: (X, Y) and P ′ :( X ′, If Y ′) is farther away, a smaller value is expected.
  • the reflected signals reflected from a plurality of targets P 1 : (X 1 , Y 1 ), P 2 : (X 2 , Y 2 ),..., P n : (X n , Y n ) are represented by Expression 13.
  • the reference signal expected to be reflected from the observation target position P: (X, Y) is F (X, Y) (t, ⁇ ).
  • the correlation S between the reflection signal R (t, ⁇ ) and the reference signal F (X, Y) (t, ⁇ ) is expressed by Expression 14.
  • Correlation S is, P 1, P 2, ⁇ , if there is a point very close to the P in P n, are expected to take a large value, P 1, P 2, ⁇ , in the P n If there is no point very close to P, it is expected to take a small value. Therefore, in order to image the presence or absence of the target at the observation target position P: (X, Y), the magnitude of the correlation S relating to the observation target position P: (X, Y) is associated with the number of gradations of the image.
  • the resolution evaluation of the synthetic aperture radar system will be described.
  • the correlation S involving P: (X, Y) and P ′ :( X ′, Y ′) is represented by P: (X, Y) and P ′ :( X ′, Y ′). Is assumed to rapidly decrease as the distance increases. Therefore, the degree to which the correlation S rapidly decreases, that is, the resolution of the synthetic aperture radar system S is evaluated.
  • the reflected signal reflected from the target (0, Y) is represented by Expression 15, and the reference signal expected to be reflected from the observation target position ( ⁇ X, Y + ⁇ Y) is represented by Expression 16.
  • the azimuth direction position of the target is set to 0, generality is not lost. Assuming that the position of the target in the azimuth direction is X, the azimuth time t may be shifted by X / v.
  • the correlation S between the reflection signal F (t, ⁇ ) and the reference signal G (t, ⁇ ) is expressed by Expression 17.
  • ⁇ R (t), R (t), and R ′ (t) are expressed as in Expression 18. Note that the correlation S shown in Expression 17 corresponds to the point extension function shown in FIGS.
  • the correlation S between the reflection signal F (t, ⁇ ) and the reference signal G (t, ⁇ ) is calculated as in Expression 19.
  • a (t) and B (t) are represented as in Expressions 20 and 21.
  • the integration range of the azimuth time t in Expression 19 extends over the azimuth time t that satisfies B (t)> A (t).
  • ⁇ (t) and ⁇ ′ (t) are represented by Expression 22.
  • FIG. 15 shows the point extension function of the present disclosure versus the distance in the range direction from the target.
  • FIG. 16 shows the point extension function of the present disclosure versus the azimuth distance from the target.
  • the center frequency f 0 is 9.25 GHz
  • the chirp pulse frequency width B W is 800 MHz
  • the chirp pulse time width ⁇ 0 is 1.0 ⁇ s
  • the beam width 2 ⁇ is 1.5 deg
  • the beam The change speed of the tilt is 1.0 deg / 100 MHz
  • the speed v of the synthetic aperture radar system S is 100 m / s
  • the distance in the range direction of the target T is 15.0 km.
  • the same range resolution is obtained when there is a beam tilt according to the present disclosure than when there is no beam tilt according to the related art. That is, in the case where the beam tilt of the present disclosure is present, the range time ⁇ during which the reflected signal from the target T exists is reduced as compared with the case where the beam tilt of the related art is not provided. However, since the azimuth time t during which the reflected signal from the target T is present increases, the same range resolution can be obtained without reducing the total time during which the reflected signal from the target T exists.
  • a synthetic aperture radar apparatus, a synthetic aperture radar signal processing apparatus, a synthetic aperture radar signal processing program, and a synthetic aperture radar observation method provide a synthetic aperture radar technique that achieves both high signal-to-noise ratio and high resolution in synthetic aperture radar technology.
  • a mechanical or electrical mechanism for controlling the beam direction is not required, and the circuit can be simplified and the cost of the system can be reduced.
  • Synthetic aperture radar system A Antenna unit T: Target 1: Synthetic aperture radar device 2: Synthetic aperture radar signal processing device 11: Chirp pulse generating unit 12: Reflected signal receiving unit 13: Antenna driving unit 21: Correlation processing executing unit

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  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

La présente invention concerne un dispositif radar à ouverture synthétique (1) comprenant : une unité de génération d'impulsion comprimée (11) qui génère une impulsion comprimée afin de comprimer la plage d'un radar à ouverture synthétique ; une unité d'antenne (A), laquelle, lors de l'émission de l'impulsion comprimée générée par l'unité de génération d'impulsion comprimée (11), entraîne la modification de la direction du faisceau rayonné dans la direction azimutale en correspondance avec la fréquence du faisceau rayonné, sans effectuer une commande directionnelle mécanique ou électronique et conformément à des caractéristiques directionnelles inhérentes ; et une unité de réception de signal de réflexion (12) qui reçoit un signal de réflexion réfléchi par une cible (T).
PCT/JP2019/029355 2018-07-26 2019-07-26 Dispositif radar à ouverture synthétique, dispositif de traitement de signal radar à ouverture synthétique, programme de traitement de signal radar à ouverture synthétique et procédé d'observation radar à ouverture synthétique WO2020022468A1 (fr)

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JP2018140682A JP7160268B2 (ja) 2018-07-26 2018-07-26 合成開口レーダ信号処理装置及び合成開口レーダ信号処理プログラム

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Cited By (1)

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WO2023209751A1 (fr) * 2022-04-25 2023-11-02 三菱電機株式会社 Radar d'image, dispositif de conception de paramètre d'observation et système radar

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JPH10232282A (ja) * 1997-02-19 1998-09-02 Mitsubishi Electric Corp 合成開口レーダ装置および移動目標検出方法
JP2000298168A (ja) * 1999-02-12 2000-10-24 Nec Corp Ｓａｒ装置
JP2006064628A (ja) * 2004-08-30 2006-03-09 Fujitsu Ten Ltd レーダ装置およびレーダ装置のアンテナ指向性調整方法
JP2007114098A (ja) * 2005-10-21 2007-05-10 Mitsubishi Space Software Kk 位置特定装置、画像再生装置、位置特定方法および位置特定プログラム
JP2010060448A (ja) * 2008-09-04 2010-03-18 Mitsubishi Electric Corp レーダ画像再生装置
JP2010175289A (ja) * 2009-01-27 2010-08-12 Toyota Motor Corp レーダ装置、及び障害物検知方法
JP2016509679A (ja) * 2013-02-08 2016-03-31 タレス アレーニア スペース イタリア ソチエタ ペル アツィオーニ コン ユニコ ソシオ 高分解能ストリップマップｓａｒイメージング

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Publication number Priority date Publication date Assignee Title
JPH10232282A (ja) * 1997-02-19 1998-09-02 Mitsubishi Electric Corp 合成開口レーダ装置および移動目標検出方法
JP2000298168A (ja) * 1999-02-12 2000-10-24 Nec Corp Ｓａｒ装置
JP2006064628A (ja) * 2004-08-30 2006-03-09 Fujitsu Ten Ltd レーダ装置およびレーダ装置のアンテナ指向性調整方法
JP2007114098A (ja) * 2005-10-21 2007-05-10 Mitsubishi Space Software Kk 位置特定装置、画像再生装置、位置特定方法および位置特定プログラム
JP2010060448A (ja) * 2008-09-04 2010-03-18 Mitsubishi Electric Corp レーダ画像再生装置
JP2010175289A (ja) * 2009-01-27 2010-08-12 Toyota Motor Corp レーダ装置、及び障害物検知方法
JP2016509679A (ja) * 2013-02-08 2016-03-31 タレス アレーニア スペース イタリア ソチエタ ペル アツィオーニ コン ユニコ ソシオ 高分解能ストリップマップｓａｒイメージング

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023209751A1 (fr) * 2022-04-25 2023-11-02 三菱電機株式会社 Radar d'image, dispositif de conception de paramètre d'observation et système radar

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