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

Radar control device, radar control method, and radar device

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

[0002] There is a radar device that repeatedly emits pulses from an antenna toward a target, and when the reflected pulses are received by the antenna, acquires a received signal of the reflected wave from the antenna. For example, Patent Document 1 discloses such a radar device that accumulates the received signal each time it acquires a received signal of a reflected wave.

[0003] Special table 2016-516177 publication

[0004] The radar device disclosed in Patent Document 1 has 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.

[0006] A radar control device according to the present disclosure includes a received signal acquisition unit that acquires a received signal of the reflected wave from the antenna when radio waves are repeatedly emitted toward the target from an antenna whose position relative to the target changes over time and when the radio waves are reflected by the target and received by the antenna, and a received signal integration unit that integrates the received signal each time the received signal is acquired by the received signal acquisition unit. The radar control device also includes a transmission period control unit that shifts the transmission period that is predicted to overlap with the reception period, which is the period during which the reflected wave is received by the antenna, among multiple transmission periods that are periods during which radio waves are repeatedly emitted from the antenna.

[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.

[0008] 1 is a configuration diagram showing a radar device including a radar control device 5 according to a first embodiment; FIG. 2 is a hardware configuration diagram showing hardware of the radar control device 5 according to the first embodiment; FIG. 3 is a hardware configuration diagram of a computer in the case where the radar control device 5 is realized by software, firmware, or the like; FIG. 4 is an explanatory diagram showing the positional relationship between an antenna 3 and a target Tgt; and FIG. 5 is a flowchart showing a radar control method which is a processing procedure of the radar control device 5. ｓｑ，η 1 is an explanatory diagram showing an example of a case where the reception period does not overlap with either the transmission period or the interference signal period when the squint angle θ is positive. ｓｑ，η 1 is an explanatory diagram showing an example of a case where the reception period does not overlap with either the transmission period or the interference signal period when the squint angle θ is negative. ｓｑ，η 1 is an explanatory diagram showing an example in which the reception interval overlaps the transmission interval when the squint angle θ is positive. ｓｑ，η 10 is an explanatory diagram showing an example in which the reception interval overlaps with the transmission interval when is negative. FIG. 11 is an explanatory diagram showing the pulse repetition period PRI after being changed by the signal processing device 6. FIG. 12 is an explanatory diagram showing the pulse repetition period PRI after being changed by the signal processing device 6.

[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 embodiment 1. Fig. 2 is a hardware configuration diagram showing the hardware of the radar control device 5 according to embodiment 1. The radar device shown in Fig. 1 includes a pulse oscillation source 1, a transmitter 2, an antenna 3, a receiver 4, the 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 the pulse repetition period PRI and outputs the pulse signal to the transmitter 2. The transmitter 2 acquires the 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, for example, a platform. The platform may be, for example, 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 convenience of explanation, in the radar device shown in FIG. 1 , the target position is assumed to be fixed. The relative position between the antenna 3 and the target changes over time. The antenna 3 radiates the modulated pulse signal output from the transmitter 2 as a radio wave toward the target. The antenna 3 also receives a wave of 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 received signal after reception processing to the radar control device 5. Specifically, as the reception processing of the received signal, the receiver 4 performs processing to demodulate the received signal of the reflected wave and outputs reception data, which is the received signal after demodulation, to the radar control device 5.

[0014] The radar control device 5 includes a received signal acquisition unit 11, a received signal integrating 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 received data.

[0015] The received signal acquisition unit 11 is realized by, for example, the received signal acquisition circuit 21 shown in Fig. 2. The received signal acquisition unit 11 acquires received data as a received signal of a reflected wave from the receiver 4. The received signal acquisition unit 11 outputs the received data to the received signal integrating unit 12.

[0016] The received signal integrating unit 12 is realized by, for example, the received signal integrating circuit 22 shown in Fig. 2. The received signal integrating unit 12 acquires received data from the received signal acquiring unit 11. The received signal integrating unit 12 integrates the received data every time it acquires the received data from the received signal acquiring unit 11. The received signal integrating unit 12 outputs the integrated received data to the signal processing device 6.

[0017] The transmission period control unit 13 is realized, for example, by the transmission period control circuit 23 shown in FIG. 2 . If any of the transmission periods, which are multiple periods during which radio waves are repeatedly emitted from the antenna 3, is predicted to overlap with a reception period, which is a period during which reflected waves are received by the antenna 3, the transmission period control unit 13 shifts the transmission period predicted to overlap with the reception period. Specifically, the transmission period control unit 13 determines whether any of the multiple transmission periods is predicted to overlap with a reception period based on the relative positions of the target and the antenna 3. If any of the transmission periods 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 integrated reception data from the reception signal integrator 12. Based on the integrated reception data, the signal processing device 6 performs, for example, imaging processing of an observation area in which a target exists.

[0019] 1, it is assumed that the received signal acquisition unit 11, the received signal integration 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. That is, it is assumed that the radar control device 5 is realized by a received signal acquisition circuit 21, a received signal integration circuit 22, and a transmission period control circuit 23. Each of the received signal acquisition circuit 21, the received signal integration circuit 22, and the 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. The computer refers to hardware that executes a program, and includes, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor).

[0021] 3 is a hardware configuration diagram of a computer when the radar control device 5 is realized by software, firmware, etc. When the radar control device 5 is realized by software, firmware, etc., a program for causing the computer to execute the respective processing procedures of the received signal acquisition unit 11, the received signal integrator 12, and the transmission period control unit 13 is stored in a 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] 4 is an explanatory diagram showing the positional relationship between the antenna 3 and the target Tgt. In FIG. 4, PF is a platform on which the antenna 3 is mounted, and v ｐ，η is the moving speed of the PF. 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 r indicates the distance from the antenna 3 to the target Tgt. 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 line of sight vector at r η０ is the synthetic aperture start time η ｓ and the synthetic aperture end time η ｅ The time η between ０ is the target line of sight vector at x ｔｇｔ is a unit vector indicating the cross-range direction of the observation area in which the target Tgt exists, y ｔｇｔ is a unit vector indicating the range direction of the observation area in which 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 of the broadside direction of the antenna 3 to 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 the oscillated pulse signal to the transmitter 2. The transmitter 2 acquires a pulse signal every time a 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 wave radiated from the antenna 3 is reflected by the observation area where the target Tgt is located. The antenna 3 receives the radio wave reflected by the observation area where the target Tgt is located, 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 received data, which is the demodulated received signal, to the radar control device 5.

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

[0028] In formula (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 a mathematical symbol indicating an 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 coordinate x of the observation area η , y η , z η and the received signal s(k η , rη ) is expressed as the following equation (2).

[0030] 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 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 The cross-range signal component, x ｔｇｔ The signal contributing to is expressed as x ｔｇｔ The integral of this wave field is the wave vector k ｘ，η Since this is done based on the wave vector k ｘ，η By the bandwidth of x ｔｇｔ The directional resolution will be determined.

[0032]

[0033] Next, the squint angle θ ｓｑ，η The relationship between the synthetic aperture center time and the synthetic aperture start time η ｓ and the synthetic aperture end time η ｅ The squint angle θ is the time between 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]

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

[0036] 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 The synthetic aperture end time η ｅ is the spatial frequency f at which equation (14) holds. ｘ，ηｅ The spatial frequency bandwidth f ｘ，ηｓ -f ｘ，ηｅ is calculated as in the following equation (15).

[0038]

[0039] Here, the synthetic aperture angle Δφ ｓｙｓ is defined 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] In 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]

[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]

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

[0046]

[0047] In the case of zero squinting, the following equation (21) holds: Therefore, equation (20) becomes equation (22) below.

[0048]

[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 |r between PF and target Tgt at zero squint ０ | and synthetic aperture time η ｅ -η ｓ Therefore, it is possible to design the synthetic aperture time η ｅ -η ｓ can be derived from the following equation (23).

[0050]

[0051] Target line-of-sight vector r when the center of the synthetic aperture 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]

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

[0054]

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

[0056]

[0057] However, r ０is the distance from PF to the target Tgt at the specified squint angle. ｘ，ｔ [m －１ s －１ ] is expressed as the following equation (27).

[0058]

[0059] The radar device shown in Fig. 1 employs a monostatic time division method in which the antenna 3 emits radio waves and then receives reflected waves. Therefore, during the period when the antenna 3 emits radio waves (hereinafter referred to as the "transmission interval"), the antenna 3 cannot receive reflected waves. Furthermore, during the period when an interference wave signal such as ground clutter reaches the antenna 3 (hereinafter referred to as the "interference signal interval"), it is desirable for the antenna 3 to avoid receiving reflected waves. Therefore, it is required that the period when the antenna 3 receives reflected waves (hereinafter referred to as the "reception interval") does not overlap with either the transmission interval or the interference signal interval. Here, it is assumed that the distance between the antenna 3 and the target Tgt at the time when the reception interval starts is R ｎｅａｒ , the distance between the antenna 3 and the target Tgt at the time when the receiving period ends is R ｆａｒ 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 n ２，ｎｅａｒ , the reception end point is n shown in equation (31) ２，ｆａｒ Let us assume that:

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

[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 ｄｕｔｙIf this is the case, then all of the following equations (32) to (34) hold true.

[0062]

[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 the equations (32) to (34) hold is also 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 ｐｌｔ and the pulse repetition period PRI set in the pulse oscillation source 1. 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 Furthermore, the transmission period control unit 13 calculates 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 The transmission period control unit 13 calculates the time uη at which the unwanted reflected signals start to arrive from the reception start timing of the unwanted reflected signals 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 from the signal processing device 6.ｓ The position of antenna 3 at the time of the synthetic aperture start η ｓ The transmission period control unit 13 acquires the position of the target Tgt at 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 The transmission period control unit 13 calculates 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 from the signal processing device 6. ｅ The position of antenna 3 at the time of the end of the synthetic aperture η ｅ The transmission period control unit 13 acquires the position of the target Tgt at 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 at ｅ The relative distance R between the antenna 3 and the target Tgt at ｆａｒ The transmission period control unit 13 calculates the relative distance R ｆａｒ By substituting into equation (30), the reception end point n １，ｆａｒ Calculate.

[0067] The transmission period control unit 13 receives from the signal processing device 6 the time uη at which the arrival of the unwanted reflected signal begins. ｓ The position of antenna 3 at time uη ｓ The transmission period control unit 13 acquires the position of the target Tgt at 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 The transmission period control unit 13 calculates 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 The transmission period control unit 13 acquires the position of the target Tgt at 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 The transmission period control unit 13 calculates 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 multiple 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 formulas (32) to (34) hold. If all of the formulas (32) to (34) hold, the reception period does not overlap with either the transmission period or the interference signal period. Each of Figures 6 and 7 is an explanatory diagram showing an example of a case where the reception period does not overlap with either the transmission period or the interference signal period. Figure 6 shows the relationship between 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. When any of the equations (32) to (34) does not hold, the reception interval overlaps with either the transmission interval or the interference signal interval. Each of Figs. 8 and 9 is an explanatory diagram showing an example of a case where the reception interval overlaps with the transmission interval. Fig. 8 shows the relationship between the squint angle θ ｓｑ，η is positive and the antenna 3 is approaching the target Tgt. ｓｑ，ηis negative, indicating a situation in which the antenna 3 is moving away from the target Tgt. In the diagram, the horizontal axis represents fast time and the vertical axis represents slow time. In each of FIGS. 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. In FIGS. 6 to 9 , the integration possible time indicates the time during which the reception signal integrator 12 can integrate the reception data. The integration impossible time indicates the time during which the reception signal integrator 12 cannot integrate the reception data.

[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 maintain the pulse repetition period PRI (step ST2 in FIG. 5 ). If any of the equations (32) to (34) are not satisfied (step ST1 in FIG. 5 : NO), the transmission period control unit 13 outputs a control command to the signal processing device 6 to change the pulse repetition period PRI so that all of the equations (32) to (34) are satisfied (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 the pulse signal to the pulse oscillation source 1. ｓｑ，ηWhen ρ 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 change by the signal processing device 6. In this case, it is desirable for the signal processing device 6 to change the pulse repetition period PRI to as short a pulse repetition period PRI as possible within a range in which all of Equations (32) to (34) hold. By changing the pulse repetition period PRI so that the pulse repetition period PRI becomes longer, as shown in Equation (36) below, 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 therefore 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. This prevents degradation of the resolution in both the cross-range direction and the elevation direction. Furthermore, it is possible to prevent deterioration of NESZ (Noise Equivalent Sigma Zero), which is the backscattering coefficient when the S / N ratio is 1, and deterioration of the false image characteristics.

[0072]

[0073] Squint angle θ ｓｑ，η When ρ 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 change by the signal processing device 6. In this case, it is desirable for the signal processing device 6 to change the pulse repetition period PRI to as long as possible within the range in which all of equations (32) to (34) hold. This allows the received data to be integrated without loss at a PRI close to the original PRI. Therefore, degradation of the resolution in both the cross-range direction and the elevation direction can be prevented. Furthermore, degradation of the NESZ and the artifact characteristics can be prevented.

[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 integrating unit 12.

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

[0077] The signal processing device 6 acquires the integrated reception data from the reception signal integrator 12. The signal processing device 6 performs imaging processing of the observation area where the target Tgt exists based on the integrated reception data. 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. Thus, 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 is acquired by the received signal acquirer 11. At this time, the received signal integrator 12 integrates the received signal every time 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.

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

[0082] REFERENCE SIGNS LIST 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 radar control device comprising: a received signal acquisition unit that acquires a received signal of the reflected wave from the antenna when radio waves are repeatedly emitted toward the target from an antenna whose position relative to the target changes over time and the reflected wave of the radio waves by the target is received by the antenna; a received signal integration unit that integrates the received signal each time the received signal is acquired by the received signal acquisition unit; and a transmission period control unit that shifts the transmission period that is predicted to overlap with the reception period, which is the period during which the reflected wave is received by the antenna, among multiple transmission periods during which the radio waves are repeatedly emitted from the antenna.

2. The relative position of the target and the antenna changes over time as a result of a change in the squint angle, which is the angle between the broadside direction of the antenna and the line of sight direction when looking at the target from the antenna, changing, and the received signal acquisition unit of the radar control device described in claim 1, characterized in that radio waves are repeatedly emitted from the antenna toward the target, and when the reflected wave of the radio waves by the target is received by the antenna, it acquires a received signal of the reflected wave from the antenna.

3. The radar control device according to claim 2, characterized in that, when the antenna is approaching the target, if there is a transmission period among the multiple 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 from the reception period.

4. A radar control device as described in claim 3, characterized in that the radio waves repeatedly radiated from the antenna towards the target are pulse signals, and the transmission period control unit, when the antenna is approaching the target, maintains the pulse repetition period of the pulse signal repeatedly radiated from the antenna if there is no transmission period among the multiple transmission periods that is predicted to overlap with the reception period, and lengthens the pulse repetition period if there is a transmission period among the multiple transmission periods that is predicted to overlap with the reception period.

5. The radar control device according to claim 2, characterized in that, when the antenna is moving away from the target, if there is a transmission period among the multiple transmission periods that is predicted to overlap with the reception period, the transmission period that is predicted to overlap with the reception period is advanced relative to the reception period.

6. A radar control device as described in claim 5, characterized in that the radio waves repeatedly radiated from the antenna towards the target are pulse signals, and the transmission period control unit, when the antenna is moving away from the target, maintains the pulse repetition period of the pulse signal repeatedly radiated from the antenna if there is no transmission period among the multiple transmission periods that is predicted to overlap with the reception period, and shortens the pulse repetition period if there is a transmission period among the multiple transmission periods that is predicted to overlap with the reception period.

7. A radar control device as described in claim 2, characterized in that the received signal integration unit integrates the received signal under the assumption that the distance between the target and the antenna at the time when integration of the received signal is started and the distance between the target and the antenna at the time when integration of the received signal is ended are the same as the distance between the target and the antenna in the line of sight direction.

8. A radar control method in which radio waves are repeatedly emitted toward a target from an antenna whose position relative to the target changes over time, and when the radio waves reflected by the target are received by the antenna, a received signal acquisition unit acquires a received signal of the reflected wave from the antenna, a received signal integration unit integrates the received signal each time it is acquired by the received signal acquisition unit, and a transmission period control unit shifts the transmission period predicted to overlap with a reception period during which the reflected wave is received by the antenna, if any of the transmission periods, which are multiple periods during which the radio waves are repeatedly emitted from the antenna, exists.

9. A radar device comprising: an antenna whose position relative to a target changes over time; a transmitter that repeatedly radiates radio waves from the antenna toward the target; a receiver that, when a reflected wave of the radio waves by the target is received by the antenna, performs reception processing of the received signal of the reflected wave and outputs the processed received signal; a received signal acquisition unit that acquires the processed received signal from the receiver; a received signal integration unit that integrates the received signal each time it is acquired by the received signal acquisition unit; a signal processing device that performs imaging processing of an observation area in which a target is present based on the integrated received signal by the received signal integration unit; and a transmission period control unit that shifts the transmission period that is predicted to overlap with the reception period, which is a period during which the reflected wave is received by the antenna, among multiple transmission periods during which the radio waves are repeatedly radiated from the antenna.

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