JPH06167566A - Radar device - Google Patents

Abstract

PURPOSE:To prevent degradation of picture quality and to eliminate deviation of position relationship on display between its own airplane and a target point by performing phase compensation and range walk compensation accurately even if the airplane makes turn. CONSTITUTION:Rotation conditions are detected by a turn condition detector 9. A position compensation data compensator 12 uses an error component data memory 11 to compensate the phase compensation data calculated by a phase compensation data calculator 10. A range walk compensator 8 performs range walk compensation using a compensation period data memory 13. When a target point enters a range where no processing can be made, control is made so that no processing is made by a process controller 19. When the position relationship on display between its own airplane and the target point deviates, the position relationship with the target is calculated by a target point coordinate calculator 20 and the display azimuth angle is controlled by a display controller 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device.

[0002]

2. Description of the Related Art FIG. 6 is a diagram showing a conventional radar device, in which 1 is a phased array antenna which radiates a transmitted wave in a space in a specific direction and receives a reflected wave, and 2 is a phase control of an array antenna module. A beam controller 3 for controlling the beam pointing of the phased array antenna 1 determines a display coordinate, and a display coordinate calculator 4 for instructing the beam pointing angle to the beam controller 4 is an excitation for generating a transmitted wave. Reference numeral 5 denotes a circulator that supplies a signal from the exciter 4 to the phased array antenna 1 and supplies a reception signal to a reception detection unit. Reference numeral 6 indicates a reception signal that converts the reception signal from the circulator 5 into a digital video reception signal. The instrument, 7 is an inertial platform sensor that detects the motion of the radar platform, and 8 is the linear change in the distance to the target ground point. Then, the cycle for shifting the range bin is calculated from the self-motion data from the inertial platform sensor 7 at the time of determining the display coordinates and the beam pointing angle data from the display coordinate calculator 3, and the range bin is shifted at a constant cycle interval. A range walk compensator 10 for performing the phase compensation data generation for calculating the phase change amount of the received signal in real time from the self-motion data from the inertial platform sensor 7 and the beam pointing angle data from the display coordinate calculator 3. A phase compensator 14 corrects the phase of the video reception signal using the phase compensation data from the phase compensation data generator 10. A FFT (Fast Fou Fou) detects a Doppler frequency corresponding to the azimuth direction in the beam.
riier Transform) calculator, 16 is the above F
An amplitude detector for detecting the amplitude of a specific frequency from the data output from the FT calculator 15, 17 is the amplitude detector 1
An image data converter for converting the data output from 6 into image data, and a display device 18 for displaying the image data output from the image data converter 17.

The conventional radar device is constructed as described above, and in FIG.
From the beam controller 2 toward the target ground point 24 of the azimuth A and the elevation B indicated by the display coordinate detector.
The phased array antenna 1 radiates a transmission wave of wavelength λ by the phase control by, and the reflected wave from the ground surface is received by the phased array antenna 1. The reflected wave passes through the circulator 5 and is converted into a digital video reception signal by the receiver 6. To be done. The distance to the target point at the observation start time (t = 0) is R (0), and the distance to the target point after t seconds is R (t). Assuming that the aircraft moves in a uniform linear motion, the distance change amount with respect to the target within the observation time T is calculated by the velocity data V from the inertial platform sensor 7 and the beam pointing angle data (A, B) from the display coordinate calculator. Is represented by VT cosA cosB. The range walk compensation period at this time is represented by r / (V cosA cosB) where r is the range resolution. The range walk compensator 8 corrects the deviation of the range bin with respect to the digital video received signal at the range walk compensation period obtained by r / (V cosA cosB).
The distance R (t) to the target point at the observation time t is the platform fluctuation data V = (V _X , V _Y , V _Z ) from the inertial platform sensor 7 and the beam pointing angle data (A from the display coordinate calculator 3). , B) is expressed by the following equation.

[0004]

[Equation 1]

Phase change dθ (t) of the received signal at this time
Is expressed by the following equation, where Δr is the second and subsequent terms of t when the square root is Taylor-expanded in Equation 1.

[0006]

[Equation 2]

Here, since Δr is very small with respect to the allowable error λ / 8, there is no problem in ignoring it. Since the phase compensation data generator 10 performs real-time processing, Δr in Equation 2
Fixed-point arithmetic with a finite bit length is performed using the following equation ignoring.

[0008]

[Equation 3]

Each term in parentheses (V _X t co
sA cosB, V _Y t sinAcosB, V _Z t
sinB) finite bit length fixed point operation result (Δ
X, ΔY, ΔZ), the calculated phase change amount Δθ
(T) is expressed by the following equation.

[0010]

[Equation 4]

The phase compensator 14 corrects the phase of the digital video received signal using the phase change amount calculated by the phase compensation data generator 10, and the FFT calculator 15
Detects the Doppler frequency corresponding to the azimuth direction in the beam, the amplitude detector 16 detects the amplitude of a specific frequency, and the image data converter 17 visualizes it to display a high-resolution ground map image on the display 18. Can be displayed.

[0012]

In the conventional radar as described above, as shown in FIG. 8, the airframe can be processed with the track 25, the velocity V = (V _X , V _Y , V _Z ) and the angular velocity ω. When making a turn to the range 26, there were the following problems. That is, in the conventional device, the calculation of the phase compensation data by the phase compensation data generator 10 is performed by finite bit length fixed point arithmetic in order to enable real-time processing, and the arithmetic error increases during turning. It was That is, assuming that the result of the finite bit length fixed point arithmetic operation of each term in the parentheses in Expression 3 is (ΔX, ΔY, ΔZ), and the error amount from each true value is (Δe _X , Δe _Y , Δe _Z ) , These are calculation errors proportional to the coefficients (K _X , K _Y , K _Z ) with respect to the motion data V = (V _X , V _Y , V _Z ) obtained from the inertial platform sensor 7,
(Δe _X , Δe _Y , Δe _Z ) = (K _X V _X , K _Y V _Y ,
It can be written as K _Z V _Z ). Assuming that the sum of the calculation errors of each term is Δe = Δe _X + Δe _Y + Δe _Z , in the case of a straight flight, V _Y ≈0, so Δe _Y ≈0, and Δe ≈Δe
_{Since X} + Δe _Z , it is within the allowable error range. Angular velocity ω
If the aircraft is turning at, Δe _Y = K _Y V
sin (ωt), so Δ
Since e increases and exceeds the allowable error of λ / 8, it is a cause of image distortion.

In the range walk compensation, the range walk compensator 8 calculates the number of range bins deviated during the observation time on the assumption that the distance change amount with respect to the target increases linearly. During a turning that does not increase to a certain level, accurate correction cannot be performed, resulting in deterioration of resolution.

Further, when the machine body turns, the angle of the target point with respect to the machine axis changes due to the time change from the display coordinate determination by the display coordinate calculator 3 to the processing, and the synthetic aperture length with respect to the target point changes. Even when there is a shortage, processing is performed to display an image for which a predetermined resolution has not been obtained.

Since a certain time is required from the determination of the display coordinates by the display coordinate calculator 3 to the display, the positional relationship in the azimuth direction between the target point by turning and the own machine is actually displayed. There was a phenomenon that it was different from the above.

The present invention has been made to solve the above problems, and stores the phase compensation amount error component data and the range walk compensation period calculated by simulation as compared with the conventional case. By
Phase compensation and range walk compensation can be performed with high accuracy even when turning is performed. Also, if the synthetic aperture length for the target point is insufficient due to the turning and the prescribed resolution cannot be obtained, the target point is not processed. Another object of the present invention is to obtain a device capable of eliminating a deviation in the azimuth direction positional relationship between the own device and the target point in the display.

[0017]

In the radar device according to the present invention, the phase compensation amount error component data obtained by simulation is stored in a memory, and the velocity fluctuation is calculated from the own motion data obtained from the inertial platform sensor. It is detected that the aircraft is in a turning state because the vector change rate is constant, and the optimum phase compensation amount error component data is used according to the velocity and angular velocity. Is to be corrected.

Further, by storing the range walk compensation period at the time of turning by the linear approximation simulation in the memory, even if the distance change amount with the target does not increase linearly, the range of the constant period is changed according to the velocity and the angular velocity. Walk compensation is performed.

Furthermore, if the synthetic aperture length for the target point becomes insufficient due to the turning and processing becomes impossible, control is performed so as not to perform processing for that point.

Further, when the positional relationship between the aircraft and the target point in the azimuth direction is deviated from the actual display due to the turning, the change in the axis from the time of coordinate determination to the display time is calculated from the angular velocity and displayed on the display. On the other hand, the display azimuth angle is controlled.

[0021]

In the present invention, according to the velocity and the angular velocity,
By accurately correcting the phase compensation data by the phase compensation data calculator by using the optimum phase compensation amount error component data, it is possible to reduce the influence of the calculation error caused by the turning.

Further, by storing the range walk compensation period at the time of turning by the linear approximation simulation in the memory, even if the distance change amount from the target does not increase linearly, the range walk compensation of the constant period has the minimum error. Can be done at.

Further, when the target point enters the unprocessable range due to the turning, it is possible not to process the target point.

When the azimuth positional relationship between the aircraft and the target point deviates from the actual display due to the turning, the present positional relationship between the target and the aircraft is calculated by starting the aircraft, and the indicator is displayed. The display azimuth can be controlled with respect to.

[0025]

【Example】

Example 1. FIG. 1 is a diagram showing an embodiment of the present invention.
1 to 7, 10 and 14 to 18 are exactly the same as the above conventional device. In addition to the operation of the conventional range walk compensator, 8 is a range walk compensator capable of inputting a range walk compensation period from the outside, and 9 is the rate of change of the velocity vector of the own motion data from the inertial platform sensor 7. When the air conditioner becomes constant, the turning condition detector that detects the turning state of the aircraft and outputs the velocity and the angular velocity, 11 is the error component data memory that stores the phase compensation amount error component data calculated by the simulation. , 12 use the error component data memory 11 to detect the phase compensation amount error corresponding to the turning condition output from the turning condition detector 9 with respect to the phase compensation data output from the phase compensation data generator 10. The phase compensation data corrector for correcting the component, 13 is a linear approximation simulation for the change in the distance to the target point during turning. Compensation cycle data memory for storing the range walk compensation cycle data calculated by ## EQU1 ## In addition to the operation of the conventional range walk compensator, the compensation cycle data is provided according to the turning condition output from the turning condition detector 9. The range walk compensator 19 for correcting the range walk using the memory 13 has a synthetic aperture length short due to a change in the axis with respect to the target point due to the turning of the aircraft during mapping, and the target point is out of the processable range. In this case, in accordance with the turning condition output from the turning condition detector 9, the change in the axis from the time when the coordinates are determined in the display coordinate detector 3 to the start of the process is calculated, and the process for that point is not performed. The processing controller 20 controls the position of the target point and the own plane in the azimuth direction by turning the aircraft during mapping. When the relation between the actual state and the displayed state is different, the change in the axis from the time when the coordinates are determined by the display coordinate calculator 3 to the display time is calculated according to the turning condition output from the turning condition detector 9. A target point coordinate calculator, 21 is a display controller for controlling the positional relationship in the azimuth direction between the own device and the target point with respect to the display device 18 based on the target point coordinate data obtained from the target point coordinate calculator 20. , 22 are timing controllers that set the time from the determination of display coordinates to the start of processing and display to the processing controller 19 and the target point coordinate calculator 20.

In the radar apparatus constructed as described above, when the turning condition detected by the turning condition detector 9 is velocity V = (V _X , V _Y , V _Z ) and angular velocity ω, phase compensation is performed. Since the phase change amount obtained by the equation 3 in the data generator 10 is a fixed-point arithmetic operation, (V _X t co
sA cosB, V _Y t sinA cosB, V _Z t
sinB) the fixed-point fixed-point arithmetic result is (ΔX, ΔY, ΔZ), and the error amount from the true value of the arithmetic result of each term is (Δe _X , Δe _Y , Δe _Z ) = (K _X V _X ，
K _Y V _Y , K _Z V _Z ). Velocity V = (V _X , V _Y ,
V _Z ), angular velocity ω, when the aircraft is turning, the calculation error of each term is (Δe _X , Δe _Y , Δe _Z ) =
(K _X V cos (ωt), K _Y V sin (ωt),
Represented by K _Z V _Z). The sum of the calculation errors of each term is Δe =
Assuming Δe _X , Δe _Y , and Δe _Z , the phase change amount calculation error 27 changes with time as shown in FIG. The phase compensation amount error component ΔE is the sum of the phase change amount calculation error 27 and the square root approximation error Δr due to Taylor expansion, and is calculated by the following equation.

[0027]

[Equation 5]

The result is stored in the error component data memory 11, and the phase compensation data calculated by the phase compensation data generator 10 is converted into the phase compensation data according to the turning condition detected by the turning condition detector 9. In the corrector 12, the calculation of the following equation is performed to correct.

[0029]

[Equation 6]

When the vehicle is turning at the velocity V and the angular velocity ω, the distance change amount 28 from the target point is represented by the following equation.

[0031]

[Equation 7]

This value becomes the curve shown in FIG. 3 which changes with time. The number of sample points is N, the time at each sample point is t _n (n is an integer of 1 to N), and the distance change amount 28 is ΔR (t _n ).

[0033]

[Equation 8]

If (a and b are arbitrary real numbers), b that minimizes Q is obtained, and if this is K, the distance change amount 2
8 is approximated by the straight line 29 having the inclination K. The range walk compensation cycle in this case is r / K, where r is the range resolution. This range walk compensation cycle is stored in the compensation cycle data memory 13 so that the compensation cycle data can be stored in accordance with the turning condition detected by the turning condition detector 9 even when the turning distance change amount does not increase linearly. The range walk compensator 8 uses the range walk compensation cycle of the memory 13 to perform range walk compensation at regular cycle intervals.

Further, in FIG. 4, when the processable angular range 30 is θ _MIN to θ _MAX , the time from the display coordinate determination by the display coordinate calculator 3 to the start of processing is set to T ₁ by the timing controller 22. From the angular velocity ω detected by the turning condition detector 9, the machine axis change 31 during this period is ω
It is represented by T ₁ . If the target point azimuth 32 based on the beam pointing angle data from the display coordinate calculator 3 is θ, then θ
When -ωT ₁ <θ _MIN or θ-ωT ₁ <θ _MAX , the processing controller 18 does not perform processing for that point because the synthetic aperture length is insufficient and a predetermined resolution cannot be obtained. To do. For example, in FIG. 4, when the target point 24 at the time of determining display coordinates enters the unprocessable range 33, the process is controlled not to be performed.

Then, in FIG. 5, the display coordinate calculator 3
Azimuth 32 of the target point based on beam pointing angle data from
Is θ and the time from display coordinate determination to display is set to T ₂ by the timing controller 22, the axis change 34 up to the display time is represented by ωT ₂ from the angular velocity detected by the turning condition detector 9. . Target point coordinate calculator 20
At ωT ₂ , the display controller 21 controls the display device 18 so that the display azimuth angle 35 is θ−ωT ₂ .

[0037]

Since the present invention is constructed as described above, it has the following effects.

By accurately correcting the phase compensation data by the phase compensation data calculator using the optimum phase compensation amount error component data, it is possible to prevent the deterioration of the image quality due to the increase of the calculation error caused by the turning.

Further, even when the distance change amount from the target does not increase linearly, the linear range walk compensation can be performed with the minimum error by the compensation cycle data according to the turning, and the deterioration of the resolution can be prevented. it can.

Further, when the angle with the target point changes due to the turning, and the processing cannot be performed because the synthetic aperture length becomes insufficient, the processing is not performed for that point, so that an image with poor image quality is displayed. You can remove the processing time you spend displaying.

When the azimuth positional relationship between the aircraft and the target point deviates on the display due to the turning, the target point coordinate calculator for calculating the azimuth positional relationship with the current target due to the movement of the aircraft. By controlling the display azimuth angle using the target point coordinate data, the display deviation can be eliminated.

[Brief description of drawings]

FIG. 1 is a diagram showing a radar device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an error amount of a phase compensation data generator.

FIG. 3 is a diagram showing a distance change amount from a target and a linear approximation thereof.

FIG. 4 is a diagram showing an unprocessable range.

FIG. 5 is a diagram showing the deviation of the azimuth angle of the target point at the time of coordinate determination and at the time of display.

FIG. 6 is a diagram showing a conventional radar device.

FIG. 7 is a diagram showing a geometrical relationship between an aircraft and a target point.

FIG. 8 is a diagram showing a trajectory of an aircraft with respect to display coordinates.

[Explanation of symbols]

 1 phased array antenna 2 beam controller 3 display coordinate calculator 4 exciter 5 circulator 6 receiver 7 inertial platform sensor 8 range walk compensator 9 turning condition detector 10 phase compensation data generator 11 error component data memory 12 phase compensation data Corrector 13 Compensation cycle data memory 14 Phase compensator 15 FFT calculator 16 Amplitude detector 17 Image data converter 18 Display 19 Processing controller 20 Target point coordinate calculator 21 Display controller 22 Timing controller 23 Radar platform 24 Target Point 25 Wake 26 Processable range 27 Phase change amount calculation error 28 Distance change from target point 29 Approximate straight line of inclination K 30 Processable range 31 Machine axis change from display coordinate determination to process start 32 Target point azimuth at coordinate determination 33 Not processable 35 Display azimuth axis changes to the display from a range 34 displayed coordinate determination

Claims (4)

[Claims] 1. A DBS (Doppler Beam S)
It is a radar that creates a high-resolution surface map using the harpening technology in real time. It uses a phased array antenna that emits a transmitted wave in a specific direction space and receives a reflected wave, and the phase control of the array antenna module. A beam controller that controls the beam pointing of the phased array antenna, a display coordinate calculator that determines the display coordinates and indicates the beam pointing angle to the beam controller, and an exciter that generates a transmitted wave. , A circulator that supplies a signal from the transmitter to the phased array antenna and supplies a received signal to the receiving detector, a receiver that converts the received signal into a digital video received signal, and an inertial platform that detects fluctuations of the radar platform Sensor and the motion data from the inertial platform sensor and the table above With the beam pointing angle data from the coordinate calculator, the range walk compensator that calculates the range bin shift cycle assuming a linear change in the distance to the target ground point, and shifts the range bin at fixed cycle intervals, From the inertial motion data from the inertial platform sensor, the rate of change of the velocity vector becomes constant, so it is detected that the aircraft is in a turning state, and a turning condition detector that outputs speed and angular velocity, and the inertia Phase compensation data generator that calculates the phase change amount of the received signal in real time based on the motion data from the platform sensor and the beam pointing angle data from the display coordinate calculator, and the phase compensation amount error calculated by simulation Using the error component data memory for storing components and the error component data memory, the phase compensation data The phase compensation data corrector that corrects the phase compensation amount error component according to the turning condition output from the turning condition detector with respect to the phase compensation data output from the generator, and the phase compensation data corrector A phase compensator that corrects the phase of the received signal using data, and an FFT (Fast Fourier Tra) that detects the Doppler frequency corresponding to the azimuth direction in the beam
nsform) arithmetic unit, an amplitude detector that detects the amplitude of a specific frequency from the data output from the FFT arithmetic unit, an image data converter that converts the data output from the amplitude detector into image data, A radar device comprising: a display for displaying image data output from the image data converter. 2. In the range walk compensator, when the vehicle is turning and the amount of change in distance to the target point does not increase linearly, the turning condition is calculated using a range walk compensation period calculated by a linear approximation simulation. 2. The radar device according to claim 1, further comprising a compensation cycle data memory for performing range walk compensation at a constant cycle interval according to the turning condition output from the detector. 3. A timing controller for setting a time from mapping coordinate determination to processing start and display, a set time from the coordinate determination set by the timing controller to processing start, and the display coordinate calculator. Of the beam pointing angle data and the turning condition output from the turning condition detector, and a processing controller for controlling not to process a point that cannot be processed due to the turning of the aircraft during mapping. The radar device according to claim 1, wherein the radar device is provided. 4. Since a fixed time is required from the determination of the mapping coordinates to the processing, the turning of the aircraft during the mapping causes the actual positional relationship between the target point and the aircraft in the azimuth direction. If the display condition is different from the display, the change in the axis from the coordinate determination to the display time is calculated by the turning condition output from the above-mentioned turning condition detector and the set time from the coordinate determination to the display by the timing controller. The target point coordinate calculator, the target point coordinate data obtained from the target point coordinate calculator, and the beam pointing angle data from the coordinate calculator are used to accurately display the positional relationship between the own device and the target point. The radar device according to claim 1, further comprising a display controller that controls the display device.