Radar control device, radar control method, and radar device

Abstract

A radar control device (5) is configured to comprise: a received signal acquiring unit (11) which, when radio waves are repeatedly emitted toward a target from an antenna (3) having a position, relative to the position of the target, that changes over time, and reflected waves of the radio waves, reflected by the target, are received by the antenna (3), acquires a received signal of the reflected wave from the antenna (3); and a received signal integrating unit (12) which integrates the received signal each time the received signal is acquired by the received signal acquiring unit (11). The radar control device (5) further comprises a transmission period control unit (13) that, if there is a transmission period, among transmission periods, which are a plurality of periods during which the radio waves are repeatedly emitted from the antenna, that is predicted to overlap a reception period, which is a period during which the reflected waves are received by the antenna (3), shifts the transmission period predicted to overlap the reception period.

Description

[Technical Field]

[0001] The present disclosure relates to a radar control device, a radar control method, and a radar device. [Background technology]

[0002] 2. Description of the Related Art There is a radar device in which pulses are repeatedly emitted from an antenna toward a target, and when the pulses are reflected by the target and received by the antenna, a received signal of the reflected waves is obtained from the antenna. As such a radar device, for example, Patent Document 1 discloses a radar device that integrates received signals each time a received signal of a reflected wave is acquired. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2016-516177 Summary of the Invention [Problem to be solved by the invention]

[0004] The radar device disclosed in Patent Document 1 had a problem in that if the period during which a pulse is emitted from the antenna overlaps with the period during which the reflected wave of the pulse from the target is received by the antenna, the received signal of the reflected wave cannot be integrated.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a radar control device that can avoid a situation in which the period during which a pulse is emitted from an antenna overlaps with the period during which the reflected wave of the pulse by a target is received by the antenna. [Means for solving the problem]

[0006] The radar control device according to the present disclosure is configured to transmit a signal to a target from an antenna whose position relative to the target changes over time. , based on pulse signalsRadio waves , for multiple transmission periods. repeatedly emitted, corresponding to each of the plurality of transmission periods Radio waves Depends on the goal The reflected wave, A plurality of reception periods corresponding to each of the plurality of transmission periods a received signal acquiring unit that acquires a received signal of a reflected wave from the antenna when the reflected wave is received by the antenna; Take Obtained Furthermore, a plurality of reception periods are used for the reflected waves of the radio waves corresponding to a plurality of transmission periods by the target. a received signal integrator that integrates received signals; Using information on the repetition period of the pulse signal, the start time and end time of each reception period, as well as the start time and end time of an interference signal period, which are multiple periods during which interference waves are received by the antenna, are calculated, and multiple Reception period Either Transmission period expected to overlap with Is there any, and During the interference signal period, Multiple Reception period Either Interference signal period predicted to overlap with If it is determined that there is a transmission period that is predicted to overlap with any one of the reception periods of the plurality of reception periods, predicted One or more The transmission period is adjusted so that there is no overlap with the reception period. When it is determined that there is an interference signal period that is predicted to overlap with any of the reception periods of the plurality of reception periods, One or more transmission periods among multiple transmission periods of, The reception period is adjusted so that there is no overlap between the reception period and the predicted interference signal period. Move to and a transmission period control unit for causing the transmission period control unit to execute the transmission period control. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to avoid a situation in which the period during which a pulse is emitted from an antenna overlaps with the period during which the reflected wave of the pulse from a target is received by the antenna. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a configuration diagram showing a radar device including a radar control device 5 according to a first embodiment. [Figure 2] 1 is a hardware configuration diagram showing hardware of a radar control device 5 according to the first embodiment. [Figure 3] FIG. 10 is a hardware configuration diagram of a computer when the radar control device 5 is realized by software, firmware, or the like. [Figure 4] 2 is an explanatory diagram showing the positional relationship between the antenna 3 and the target Tgt. FIG. [Figure 5] 3 is a flowchart showing a radar control method, which is a processing procedure of the radar control device 5. [Figure 6] FIG. 10 is an explanatory diagram showing an example of a case where the reception interval does not overlap with either the transmission interval or the interference signal interval when the squint angle θsq,η is positive. [Figure 7] FIG. 10 is an explanatory diagram showing an example of a case where the reception interval does not overlap with either the transmission interval or the interference signal interval when the squint angle θsq,η is negative. [Figure 8] FIG. 10 is an explanatory diagram showing an example in which the reception interval overlaps the transmission interval when the squint angle θsq,η is positive. [Figure 9] FIG. 10 is an explanatory diagram showing an example in which the reception interval overlaps the transmission interval when the squint angle θsq,η is negative. [Figure 10] 10 is an explanatory diagram showing the pulse repetition period PRI after being changed by the signal processing device 6. FIG. [Figure 11] 10 is an explanatory diagram showing the pulse repetition period PRI after being changed by the signal processing device 6. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] In order to explain the present disclosure in more detail, embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0010] Embodiment 1 FIG. 1 is a configuration diagram showing a radar device including a radar control device 5 according to the first embodiment. FIG. 2 is a hardware configuration diagram showing the hardware of the radar control device 5 according to the first embodiment. The radar device shown in FIG. 1 includes a pulse oscillation source 1, a transmitter 2, an antenna 3, a receiver 4, a radar control device 5, and a signal processing device 6.

[0011] The pulse oscillation source 1 has a pulse repetition period PRI (=1 / PRF) set by the signal processing device 6. PRF is the pulse repetition frequency. The pulse oscillation source 1 repeatedly oscillates a pulse signal at a pulse repetition period PRI and outputs the pulse signal to the transmitter 2 . The transmitter 2 receives a pulse signal from the pulse oscillation source 1 . The transmitter 2 modulates the pulse signal and outputs the modulated pulse signal to the antenna 3 .

[0012] The antenna 3 is mounted on a platform, for example, such as an artificial satellite or an airplane. The position of the antenna 3 changes over time. The position of the target may change over time, or may be fixed. For the sake of convenience, in the radar device shown in FIG. 1, the target position is assumed to be fixed. The relative positions of the antenna 3 and the target change over time. The antenna 3 radiates the modulated pulse signal output from the transmitter 2 as a radio wave toward a target. The antenna 3 also receives the radio wave reflected by the target and outputs a received signal of the reflected wave to the receiver 4.

[0013] The receiver 4 acquires the received signal of the reflected wave from the antenna 3 . The receiver 4 performs reception processing on the received signal of the reflected wave, and outputs the processed received signal to the radar control device 5. Specifically, the receiver 4 performs a process of demodulating the received signal of the reflected wave as a reception process of the received signal, and outputs reception data, which is the demodulated reception signal, to the radar control device 5.

[0014] The radar control device 5 includes a received signal acquisition unit 11, a received signal integration unit 12, and a transmission period control unit 13. The radar control device 5 is a device that controls the period during which radio waves are emitted from the antenna 3 and also integrates the received data.

[0015] The received signal acquisition unit 11 is realized by, for example, a received signal acquisition circuit 21 shown in FIG. The received signal acquisition unit 11 acquires received data from the receiver 4 as a received signal of the reflected wave. The received signal acquisition unit 11 outputs the received data to the received signal integrator 12 .

[0016] The received signal integrator 12 is realized by, for example, a received signal integrator circuit 22 shown in FIG. The received signal integrator 12 acquires the received data from the received signal acquirer 11 . The received signal integrator 12 integrates the received data every time it acquires the received data from the received signal acquirer 11 . The received signal integrator 12 outputs the integrated received data to the signal processor 6.

[0017] The transmission period control unit 13 is realized by, for example, the transmission period control circuit 23 shown in FIG. If there is a transmission period among the multiple transmission periods during which radio waves are repeatedly emitted from the antenna 3 that is predicted to overlap with a reception period during which reflected waves are received by the antenna 3, the transmission period control unit 13 shifts the transmission period that is predicted to overlap with the reception period. Specifically, the transmission period control unit 13 determines, based on the relative positions of the target and the antenna 3, whether or not there is a transmission period among the multiple transmission periods that is predicted to overlap with a reception period. If there is a transmission period that is predicted to overlap with a reception period, the transmission period control unit 13 controls, for example, the pulse repetition period PRI of the pulse signal oscillated from the pulse oscillation source 1 via the signal processing device 6 so that the transmission period predicted to overlap with the reception period does not overlap with the reception period.

[0018] The signal processing device 6 sets the pulse repetition period PRI in the pulse oscillation source 1. The signal processing device 6 acquires the accumulated received data from the received signal integrating unit 12. The signal processing device 6 performs, for example, imaging processing of an observation area in which a target exists, based on the received data after integration.

[0019] 1, it is assumed that the received signal acquisition unit 11, the received signal integrating unit 12, and the transmission period control unit 13, which are components of the radar control device 5, are each realized by dedicated hardware as shown in Fig. 2. In other words, it is assumed that the radar control device 5 is realized by a received signal acquisition circuit 21, a received signal integrating circuit 22, and a transmission period control circuit 23. Each of the received signal acquisition circuit 21, received signal integration circuit 22, and transmission period control circuit 23 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof.

[0020] The components of the radar control device 5 are not limited to those realized by dedicated hardware, and the radar control device 5 may be realized by software, firmware, or a combination of software and firmware. The software or firmware is stored as a program in the memory of a computer. A computer refers to hardware that executes the program, such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP (Digital Signal Processor).

[0021] FIG. 3 is a hardware configuration diagram of a computer when the radar control device 5 is realized by software, firmware, or the like. When the radar control device 5 is realized by software, firmware, or the like, a program for causing a computer to execute the respective processing procedures of the received signal acquisition unit 11, the received signal integrator 12, and the transmission period controller 13 is stored in the memory 31. Then, a processor 32 of the computer executes the program stored in the memory 31.

[0022] 2 shows an example in which each of the components of the radar control device 5 is realized by dedicated hardware, while Fig. 3 shows an example in which the radar control device 5 is realized by software, firmware, etc. However, this is merely an example, and some of the components in the radar control device 5 may be realized by dedicated hardware, and the remaining components may be realized by software, firmware, etc.

[0023] FIG. 4 is an explanatory diagram showing the positional relationship between the antenna 3 and the target Tgt. In FIG. 4, PF is the platform on which the antenna 3 is mounted, and v p,η is the movement speed of the PF. r η is a vector in the line of sight direction when the target Tgt is viewed from the antenna 3 (hereinafter referred to as the "target line of sight vector"), and the target line of sight vector r η The magnitude of indicates the distance from the antenna 3 to the target Tgt. r ηs is the synthetic aperture start time η, which is the time when the received signal integrator 12 starts integrating the received signals. s is the target gaze vector at r ηe is the synthetic aperture end time η, which is the time when the integration of the received signals by the received signal integration unit 12 ends. e is the target gaze vector at r η0 is the synthetic aperture start time η s and the synthetic aperture end time η e is the target line of sight vector at time η0 between x tgt is a unit vector indicating the cross-range direction of the observation area where the target Tgt exists, ytgt is a unit vector indicating the range direction of the observation area where the target Tgt exists, z tgt is a unit vector indicating the elevation direction. θ is the squint angle. The squint angle θ is the ratio between the broadside direction of antenna 3 and the target line-of-sight vector r η0 The angle between

[0024] Next, the operation of the radar device shown in FIG. 1 will be described. The pulse oscillation source 1 repeatedly oscillates a pulse signal at a pulse repetition period PRI. The pulse oscillation source 1 outputs an oscillated pulse signal to the transmitter 2 . The transmitter 2 acquires a pulse signal every time the pulse signal is output from the pulse oscillation source 1. The transmitter 2 modulates the acquired pulse signal and outputs the modulated pulse signal to the antenna 3 .

[0025] The antenna 3 radiates the modulated pulse signal output from the transmitter 2 as a radio wave toward the target Tgt. The radio waves emitted from the antenna 3 are reflected into the observation area where the target Tgt exists. The antenna 3 receives the radio wave reflected by the observation area in which the target Tgt exists, and outputs a received signal of the reflected wave to the receiver 4.

[0026] The receiver 4 acquires the received signal of the reflected wave from the antenna 3 . The receiver 4 demodulates the received signal of the reflected wave and outputs the demodulated received signal as reception data to the radar control device 5.

[0027] Here, the synthetic aperture start time η s and synthetic aperture end time η e Each of these will be explained below. The received signal s(k η ,r η ) is expressed by the following formula (1).

[0028] TIFF0007814625000001.tif13166 In equation (1), k η is the wave vector of the reflected wave, and r η is the target line of sight vector indicating the distance from the antenna 3 to the target Tgt. A indicates amplitude and exp is the mathematical symbol for the exponential function.

[0029] wave vector k η is the orthogonally decomposed wave vector k x,η ,k y,η ,k z,η and the image coordinates of the observation area x η ,y η ,z η and the received signal s(k η ,r η ) is expressed as the following equation (2):

[0030] TIFF0007814625000002.tif69166 In formulas (3) to (8), x tgt is the image coordinate x η y is a unit vector indicating the cross-range direction in tgt is the image coordinate y η z, a unit vector indicating the range direction in tgt is the image coordinate z η is a unit vector indicating the elevation direction at

[0031] The cross-range resolution of the observation area is given by the wave vector k x,η The range resolution of the observation area is calculated from the bandwidth of the wave vector k y,η It is calculated from the bandwidth of The cross-range signal component, x tgt The signal contributing to is x as shown in the following equation (9): tgt The integral of this wave field is the wave vector k x,η Since this is done based on the wave vector kx,η With the bandwidth of x tgt The directional resolution will be determined.

[0032] TIFF0007814625000003.tif11166

[0033] Next, the squint angle θ sq,η The relationship between the time and the synthetic aperture center time will be explained. The synthetic aperture center time is the synthetic aperture start time η s and the synthetic aperture end time η e The time between Squint angle θ sq,η is expressed as the following equation (10): As shown in the following equation (11), the squint angle θ sq,η is the specified squint angle θ sq The time that coincides with η c Let us assume that:

[0034] TIFF0007814625000004.tif34166

[0035] As shown in the following equation (12), the spatial frequency f x,η By defining |x in equation (3), tgt If |=1, the following equations (13) and (14) are derived.

[0036] TIFF0007814625000005.tif49166 In equations (13) and (14), η c is the squint angle θ sq,η is the specified squint angle θ sq Δx is the required cross-range resolution, U over,cr is the cross-range oversampling rate.

[0037] Synthetic opening start time η s is the spatial frequency f at which equation (13) holds. x,ηs It can be calculated from the time. Synthetic aperture end time η e is the spatial frequency f at which equation (14) holds. x,ηe It can be calculated from the time. Spatial frequency bandwidth f x,ηs -f x,ηe is calculated as shown in the following equation (15).

[0038] TIFF0007814625000006.tif18166

[0039] Here, the synthetic aperture angle Δφ sys If we define as in the following equation (16), the spatial frequency bandwidth f x,ηs -f x,ηe can be rearranged as shown in the following equation (17).

[0040] TIFF0007814625000007.tif39166 In the equations (16) and (17), λ is the wavelength of the pulse signal.

[0041] Moreover, equation (17) can be rearranged as in equation (18) below.

[0042] TIFF0007814625000008.tif23166

[0043] Here, the target line of sight vector r η To estimate , it is necessary to integrate the velocity of the PF as shown in equation (19) below.

[0044] TIFF0007814625000009.tif20166

[0045] Using equation (19), equation (18) can be rearranged as equation (20) below.

[0046] TIFF0007814625000010.tif36166

[0047] In the zero squint, the following equation (21) holds: Therefore, equation (20) becomes the following equation (22).

[0048] TIFF0007814625000011.tif86166

[0049] Therefore, the design at zero squint is based on the velocity of the PF at zero squint, v p,0 and the relative distance |r0| between the PF and the target Tgt at zero squint, and the synthetic aperture time η e -η s Therefore, it is possible to design it. Synthetic opening time η e -η s can be derived from the following equation (23).

[0050] TIFF0007814625000012.tif19166

[0051] Target line-of-sight vector r when the synthetic aperture center is not zero squint η is the slow time η at the reference squint angle, as shown in the following equation (24). c can be converted into an integral form of the target line of sight vector based on

[0052] TIFF0007814625000013.tif19166

[0053] Therefore, equation (22) can be rearranged as equation (25) below.

[0054] TIFF0007814625000014.tif41166

[0055] However, |r ηc |=r ηc Synthetic aperture time ηe -η s can be approximated as the following equation (26).

[0056] TIFF0007814625000015.tif36166

[0057] where r0 is the distance from the PF to the target Tgt at the specified squint angle. x,t [m -1 s -1 ] is expressed as the following equation (27).

[0058] TIFF0007814625000016.tif18166

[0059] The radar device shown in FIG. 1 employs a monostatic time division system in which the antenna 3 emits radio waves and then receives reflected waves. Therefore, during the period when the antenna 3 is emitting radio waves (hereinafter referred to as the "transmission period"), the antenna 3 cannot receive reflected waves. Also, during the period when interference wave signals such as ground clutter reach the antenna 3 (hereinafter referred to as the "interference signal period"), it is desirable for the antenna 3 to avoid receiving reflected waves. For this reason, it is required that the period during which the antenna 3 receives the reflected wave (hereinafter referred to as the "reception period") does not overlap with either the transmission period or the interference signal period. Here, the distance between the antenna 3 and the target Tgt at the time when the receiving interval starts is R near , the distance between the antenna 3 and the target Tgt at the time when the receiving interval ends is R far Let us assume that: Then, with the start timing of the transmission pulse as a reference, the reception start point normalized by PRI is n 1,near , the reception end point is n shown in Equation (30) 1,far Also, the height H plt The reception start point normalized by PRI is calculated as n2,near , the reception end point is n shown in Equation (31) 2,far Let us assume that:

[0060] TIFF0007814625000017.tif104166 In equations (28) to (31), c is the speed of light, T p is the transmit pulse width including margin. mod(□) is a mathematical symbol that leaves only the decimal part of □.

[0061] When the reception period does not overlap with the transmission period or the interference signal period, the duty of the transmission pulse including the margin is D duty If this is the case, then all of the following equations (32) to (34) hold true.

[0062] TIFF0007814625000018.tif56166

[0063] In a situation where the relative position between the antenna 3 and the target Tgt changes at high speed, the squint angle at a certain time η is θ sq,η and R f,η =R f +V η sinθ sq,η , R n,η =R n +V η sinθ sq,η Then, the distance between the antenna 3 and the target Tgt is determined by the squint angle θ sq,η Relative velocity V according to η sinθ sq,η At this time, the PRI for which equations (32) to (34) hold also becomes a function of time η.

[0064] Next, the operation of the radar control device 5 will be described. FIG. 5 is a flowchart showing a radar control method, which is a processing procedure of the radar control device 5. The transmission period control unit 13 receives from the signal processing device 6 the start timing of the transmission pulse set in the pulse oscillation source 1 and the height H pltThe timing at which reception of the unwanted reflected signal begins and the pulse repetition period PRI set in the pulse oscillation source 1 are acquired. The transmission period control unit 13 determines the synthetic aperture start time η as the time to start receiving the reflected wave from the start timing of the transmission pulse and the pulse repetition period PRI. s Calculate. Furthermore, the transmission period control unit 13 determines the synthetic aperture end time η as the time to end reception of the reflected wave from the start timing of the transmission pulse and the pulse repetition period PRI. e Calculate. The transmission period control unit 13 calculates the time uη at which the unwanted reflected signal starts to arrive from the reception start timing of the unwanted reflected signal and the pulse repetition period PRI. s and the time uη when the arrival of the unwanted reflected signal ends e and calculate.

[0065] The transmission period control unit 13 receives the synthetic aperture start time η s The position of antenna 3 at the time of the synthetic aperture start η s Obtain the position of the target Tgt at and. The transmission period control unit 13 determines the synthetic aperture start time η s The position of antenna 3 at the time of the synthetic aperture start η s From the position of the target Tgt at s The relative distance R between the antenna 3 and the target Tgt at near Calculate. The transmission period control unit 13 determines the relative distance R near By substituting into equation (28), the reception start point n 1,near Calculate.

[0066] The transmission period control unit 13 receives the synthetic aperture end time η e The position of antenna 3 at the time of the end of the synthetic aperture η e Obtain the position of the target Tgt at and. The transmission period control unit 13 determines the synthetic aperture end time η e The position of antenna 3 at the time of the end of the synthetic aperture η e From the position of the target Tgt ate The relative distance R between the antenna 3 and the target Tgt at far Calculate. The transmission period control unit 13 determines the relative distance R far By substituting into equation (30), the receiving end point n 1,far Calculate.

[0067] The transmission period control unit 13 receives from the signal processing device 6 the time uη s The position of antenna 3 at time uη s Obtain the position of the target Tgt at and. The transmission period control unit 13 receives the time uη s The position of antenna 3 at time uη s From the position of the target Tgt at time uη s The relative distance R between the antenna 3 and the target Tgt at near Calculate. The transmission period control unit 13 determines the relative distance R near By substituting into equation (29), the reception start point n 2,near Calculate.

[0068] The transmission period control unit 13 receives from the signal processing device 6 the time uη when the arrival of the unwanted reflected signal ends. e The position of antenna 3 at time uη e Obtain the position of the target Tgt at and. The transmission period control unit 13 receives the time uη e The position of antenna 3 at time uη e From the position of the target Tgt at time uη e The relative distance R between the antenna 3 and the target Tgt at far Calculate. The transmission period control unit 13 determines the relative distance R far By substituting into equation (31), the reception start point n 2,far Calculate.

[0069] The transmission period control unit 13 determines whether or not there is a transmission period among the plurality of transmission periods that is predicted to overlap with a reception period. That is, the transmission period control unit 13 determines whether or not all of the equations (32) to (34) hold. When all of the formulas (32) to (34) are satisfied, the reception interval does not overlap with either the transmission interval or the interference signal interval. 6 and 7 are explanatory diagrams showing examples in which the reception interval does not overlap with the transmission interval and the interference signal interval, respectively. Figure 6 shows the squint angle θ sq,η is positive and the antenna 3 is approaching the target Tgt. sq,η is negative, indicating that the antenna 3 is moving away from the target Tgt. In the figure, the horizontal axis represents fast time and the vertical axis represents slow time. If any of the equations (32) to (34) does not hold, the reception interval overlaps with either the transmission interval or the interference signal interval. 8 and 9 are explanatory diagrams each showing an example in which the reception interval overlaps with the transmission interval. Figure 8 shows the squint angle θ sq,η is positive and the antenna 3 is approaching the target Tgt. sq,η is negative, indicating that the antenna 3 is moving away from the target Tgt. In the figure, the horizontal axis represents fast time and the vertical axis represents slow time. 8 and 9, the second transmission interval from the left in the third slow time from the top overlaps with the reception interval. When the transmission interval overlaps with the reception interval, the reception signal integrator 12 cannot integrate the reception data, resulting in a deterioration of the S / N (Signal to Noise) ratio. 6 to 9, the integration possible time indicates the time during which the received data can be integrated by the received signal integration unit 12. The integration impossible time indicates the time during which the received data cannot be integrated by the received signal integration unit 12.

[0070] If all of the equations (32) to (34) are satisfied (step ST1 in FIG. 5: YES), the transmission period control unit 13 outputs a control command to the signal processing device 6 to instruct it to maintain the pulse repetition period PRI (step ST2 in FIG. 5). If any of the equations (32) to (34) does not hold (step ST1 in FIG. 5: NO), the transmission period control unit 13 outputs a control command to the signal processing device 6 to instruct it to change the pulse repetition period PRI so that all of the equations (32) to (34) hold (step ST3 in FIG. 5).

[0071] When the signal processing device 6 receives a control command from the transmission period control unit 13 instructing to change the pulse repetition period PRI, it changes the pulse repetition period PRI set in the pulse oscillation source 1 so that all of the equations (32) to (34) hold, and then outputs an oscillation command for a pulse signal to the pulse oscillation source 1. Squint angle θ sq,η If is positive, for example, under the circumstances shown in FIG. 8, the signal processing device 6 changes the pulse repetition period PRI so that the pulse repetition period PRI becomes longer. FIG. 10 is an explanatory diagram showing the pulse repetition period PRI after being changed by the signal processing device 6. As shown in FIG. At this time, it is desirable that the signal processing device 6 change the pulse repetition period PRI to as short a period as possible within the range in which all of the equations (32) to (34) hold. By changing the pulse repetition period PRI so that it becomes longer, as shown in the following equation (36), the received signal integrator 12 can integrate the received data even if the relative distance R between the antenna 3 and the target Tgt becomes longer than the distance ΔR at which aliasing occurs. As a result, even if the relative distance R between the antenna 3 and the target Tgt changes rapidly and becomes longer than the distance ΔR at which aliasing occurs, the received data can be integrated without loss at a PRI close to the original PRI. Therefore, it is possible to prevent degradation of the resolution in both the cross-range direction and the elevation direction. In addition, it is possible to prevent degradation of NESZ (Noise Equivalent Sigma Zero), which is the backscattering coefficient when the S / N ratio is 1, and degradation of the false image characteristics.

[0072] TIFF0007814625000019.tif16166

[0073] Squint angle θ sq,η If is negative, for example, under the circumstances shown in FIG. 9, the signal processing device 6 changes the pulse repetition period PRI so that the pulse repetition period PRI becomes shorter. FIG. 11 is an explanatory diagram showing the pulse repetition period PRI after being changed by the signal processing device 6. As shown in FIG. At this time, it is desirable that the signal processing device 6 change the pulse repetition period PRI to as long as possible within the range in which all of the equations (32) to (34) hold. This allows the received data to be accumulated without loss at a PRI close to the original PRI. This prevents degradation of the resolution in both the cross-range and elevation directions. It also prevents degradation of the NESZ and artifact characteristics.

[0074] When the signal processing device 6 receives a control command from the transmission period control unit 13 instructing it to maintain the pulse repetition period PRI, it maintains the pulse repetition period PRI set in the pulse oscillation source 1 and outputs an oscillation command for a pulse signal to the pulse oscillation source 1.

[0075] The received signal acquisition unit 11 acquires the received data from the receiver 4 (step ST4 in FIG. 5). The received data is converted by the receiver 4 into a received signal s(k η ,r η ) is the demodulated signal. The received signal acquisition unit 11 outputs the received data to the received signal integrator 12 .

[0076] The received signal integrator 12 acquires the received data from the received signal acquirer 11 . The received signal integrator 12 integrates the received data every time it acquires the received data from the received signal acquirer 11. That is, the received signal integrator 12 integrates the received data in a plurality of reception intervals (step ST5 in FIG. 5). The received signal integrator 12 outputs the integrated received data to the signal processor 6.

[0077] The signal processing device 6 acquires the accumulated received data from the received signal integrating unit 12. Based on the integrated received data, the signal processing device 6 performs imaging processing of the observation area where the target Tgt exists. The imaging processing of the observation area itself is a known technique, and therefore a detailed description thereof will be omitted.

[0078] In the first embodiment described above, the radar control device 5 is configured to include a received signal acquisition unit 11 that acquires a received signal of the reflected wave from the antenna 3 when the radio wave is repeatedly emitted toward the target from the antenna 3, whose position relative to the target changes over time, and a received signal integration unit 12 that integrates the received signal each time the received signal is acquired by the received signal acquisition unit 11. The radar control device 5 also includes a transmission period control unit 13 that, if any of the transmission periods, which are multiple periods during which the radio wave is repeatedly emitted from the antenna 3, is predicted to overlap with a reception period, which is a period during which the reflected wave is received by the antenna 3, shifts the transmission period predicted to overlap with the reception period. Therefore, the radar control device 5 can avoid a situation in which the transmission period during which a pulse is emitted from the antenna overlaps with the reception period during which the pulse reflected by the target is received by the antenna.

[0079] In the radar control device 5 shown in FIG. 1, the received signal integrator 12 integrates the received signal every time the received signal acquirer 11 acquires the received signal. At this time, the received signal integrator 12 calculates the synthetic aperture start time η s The distance between the target Tgt and the antenna 3 and the synthetic aperture end time η e The distance between the target Tgt and the antenna 3 is expressed as the target line of sight vector r η0 It is also possible to perform an approximation process of integrating the received signals on the assumption that the distance between the target Tgt and the antenna 3 in the line of sight direction indicated by is equal to the distance between the target Tgt and the antenna 3. By performing such an approximation process, it is possible to reduce the load of the integration process of the received signals.

[0080] In addition, in the present disclosure, any of the components of the embodiments may be modified or omitted. [Industrial Applicability]

[0081] The present disclosure is suitable for a radar control device, a radar control method, and a radar device. [Explanation of symbols]

[0082] 1 pulse oscillation source, 2 transmitter, 3 antenna, 4 receiver, 5 radar control device, 6 signal processing device, 11 received signal acquisition unit, 12 received signal integrating unit, 13 transmission period control unit, 21 received signal acquisition circuit, 22 received signal integrating circuit, 23 transmission period control circuit, 31 memory, 32 processor.

Claims

1. a radio wave based on a pulse signal is repeatedly emitted toward a target from an antenna whose position relative to the target changes over time, for a plurality of transmission periods; When the reflected waves of the radio waves corresponding to each of the plurality of transmission periods by the target are received by the antenna during a plurality of reception periods corresponding to each of the plurality of transmission periods, a received signal acquisition unit that acquires a received signal of the reflected wave from the antenna; a received signal integrating unit that integrates a plurality of received signals corresponding to a plurality of reception periods, the received signals being acquired by the received signal acquiring unit, for the reflected waves of the radio waves by the target corresponding to the plurality of transmission periods; Using information on the repetition period of the pulse signal, calculate the start time and end time of each of the reception periods, and the start time and end time of an interference signal period, which is a plurality of periods during which an interference wave is received by the antenna; Whether any of the plurality of transmission periods is expected to overlap with any of the plurality of reception periods; and determining whether the interference signal period includes an interference signal period that is predicted to overlap with any of the plurality of reception periods; When it is determined that there is a transmission period that is predicted to overlap with any one of the reception periods of the plurality of reception periods, one or more transmission periods that are predicted to overlap with the reception period are shifted so that they do not overlap with the reception period; when it is determined that there is an interfering signal period that is predicted to overlap with any one of the plurality of reception periods, shifting one or more transmission periods among the plurality of transmission periods so that there is no overlap between the reception period and the predicted interfering signal period; a transmission period control section; A radar control device comprising:

2. a squint angle, which is the angle between the broadside direction of the antenna and the line of sight direction of the target from the antenna, changes over time, thereby changing the relative position of the target and the antenna; The received signal acquisition unit 2. The radar control device according to claim 1, wherein the radio waves are repeatedly emitted from the antenna toward the target, and when the radio waves are reflected by the target and received by the antenna, a received signal of the reflected waves is obtained from the antenna.

3. The transmission period control unit 3. The radar control device according to claim 2, wherein, when the antenna is approaching the target, if there is a transmission period among the plurality of transmission periods that is predicted to overlap with the reception period, the transmission period that is predicted to overlap with the reception period is delayed with respect to the reception period.

4. The transmission period control unit 3. The radar control device according to claim 2, wherein, when the antenna is moving away from the target, if there is a transmission period among the plurality of transmission periods that is predicted to overlap with the reception period, the transmission period that is predicted to overlap with the reception period is made earlier than the reception period.

5. The received signal integrator 3. The radar control device according to claim 2, wherein the received signals are integrated on the assumption that the distance between the target and the antenna at the time when integration of the received signals is started and the distance between the target and the antenna at the time when integration of the received signals is ended are the same as the distance between the target and the antenna in the line of sight direction.

6. a radio wave based on a pulse signal is repeatedly emitted toward a target from an antenna whose position relative to the target changes over time, for a plurality of transmission periods; When the reflected waves of the radio waves corresponding to each of the plurality of transmission periods by the target are received by the antenna during a plurality of reception periods corresponding to each of the plurality of transmission periods, a received signal acquisition unit that acquires a received signal of the reflected wave from the antenna; a reception signal integrating unit integrating a plurality of reception signals corresponding to a plurality of reception periods, the reception signals being acquired by the reception signal acquiring unit, for the reflected waves of the radio waves by the target corresponding to the plurality of transmission periods; The transmission period control unit Using information on the repetition period of the pulse signal, calculate the start time and end time of each of the reception periods, and the start time and end time of an interference signal period, which is a plurality of periods during which an interference wave is received by the antenna; Whether any of the plurality of transmission periods is expected to overlap with any of the plurality of reception periods; and determining whether the interference signal period includes an interference signal period that is predicted to overlap with any of the plurality of reception periods; When it is determined that there is a transmission period that is predicted to overlap with any one of the reception periods of the plurality of reception periods, one or more transmission periods that are predicted to overlap with the reception period are shifted so that they do not overlap with the reception period; when it is determined that there is an interfering signal period that is predicted to overlap with any one of the plurality of reception periods, shifting one or more transmission periods among the plurality of transmission periods so that there is no overlap between the reception period and the predicted interfering signal period; Radar control method.

7. an antenna whose position relative to the target position changes over time; a transmitter that repeatedly radiates radio waves based on a pulse signal from the antenna toward the target for a plurality of transmission periods; When the reflected waves of the radio waves corresponding to each of the plurality of transmission periods by the target are received by the antenna during a plurality of reception periods corresponding to each of the plurality of transmission periods, a receiver that performs reception processing on a received signal of the reflected wave and outputs the received signal after reception processing; a received signal acquisition unit that acquires the received signal after the reception processing from the receiver; a received signal integrating unit that integrates a plurality of received signals corresponding to a plurality of reception periods, the received signals being acquired by the received signal acquiring unit, for the reflected waves of the radio waves by the target corresponding to the plurality of transmission periods; a signal processing device that performs imaging processing of an observation area in which the target exists based on the received signals after integration by the received signal integration unit; Using information on the repetition period of the pulse signal, calculate the start time and end time of each of the reception periods, and the start time and end time of an interference signal period, which is a plurality of periods during which an interference wave is received by the antenna; Whether any of the plurality of transmission periods is expected to overlap with any of the plurality of reception periods; and determining whether the interference signal period includes an interference signal period that is predicted to overlap with any of the plurality of reception periods; When it is determined that there is a transmission period that is predicted to overlap with any one of the reception periods of the plurality of reception periods, one or more transmission periods that are predicted to overlap with the reception period are shifted so that they do not overlap with the reception period; when it is determined that there is an interfering signal period that is predicted to overlap with any one of the plurality of reception periods, shifting one or more transmission periods among the plurality of transmission periods so that there is no overlap between the reception period and the predicted interfering signal period; a transmission period control section; A radar device comprising:

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