JP2910464B2 - Radar equipment - Google Patents

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 apparatus, in which 1 is a phased array antenna which radiates a transmission wave in a space in a specific direction and receives a reflected wave, and 2 is a phased array antenna by phase control of an array antenna module. A beam controller 3 for controlling the beam directivity of the phased array antenna 1 determines display coordinates, a display coordinate calculator for instructing the beam controller on a beam directivity angle, and 4 is an excitation for generating a transmission wave. A circulator 5 supplies a signal from the exciter 4 to the phased array antenna 1 and supplies a reception signal to a reception detector. A reception device 6 converts a reception signal from the circulator 5 into a digital video reception signal. 7 is an inertial platform sensor that detects the movement of the radar platform, and 8 is a linear and temporary change in the distance to the target surface point. Then, a cycle of shifting the range bin is calculated from the own motion data from the inertial platform sensor 7 at the time of determining the display coordinates and the beam directing angle data from the display coordinate calculator 3, and the range bin is shifted at regular intervals. The range walk compensator 10 performs phase compensation data generation for calculating the amount of phase change of the received signal in real time from the own motion data from the inertial platform sensor 7 and the beam pointing angle data from the display coordinate calculator 3. 14 is a phase compensator for correcting the phase of the video reception signal using the phase compensation data from the phase compensation data generator 10, and 15 is an FFT (Fast Fou) for detecting a Doppler frequency corresponding to an azimuthal direction in the beam.
rier Transform) computing unit, 16 is F
An amplitude detector for detecting the amplitude of a specific frequency from the data output from the FT calculator 15, and 17 is the amplitude detector 1
An image data converter 18 converts the data output from 6 into image data, and a display 18 displays the image data output from the image data converter 17.

[0003] A conventional radar apparatus is constructed as described above.
From the beam controller 2 toward the target ground point 24 at the azimuth A and the elevation B indicated by the display coordinate detector.
Transmits a wave of wavelength λ from the phased array antenna 1 by phase control by the phase control, and receives a reflected wave from the ground surface by the phased array antenna 1, and the reflected wave passes through the circulator 5 and is converted into a digital video reception signal by the receiver 6. Is 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 linearly at a constant speed, the amount of change in distance from the target within the observation time T is represented by the velocity data V from the inertial platform sensor 7 and the beam pointing angle data (A, B) from the display coordinate calculator. And expressed as VT cosA cosB. At this time, the range walk compensation period 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 reception signal at a range walk compensation period determined by r / (V cosA cosB).
The distance R (t) from the target point at the observation time t is determined by the platform swing data V = (V _X , V _Y , V _Z ) from the inertial platform sensor 7 and the beam directional angle data (A) from the display coordinate calculator 3. , B) is represented by the following equation.

[0004]

(Equation 1)

At this time, the phase change dθ (t) of the received signal is obtained.
Is represented 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 if it is ignored. Since the phase compensation data generator 10 performs real-time processing, Δr
The fixed-point operation of the finite bit length is performed using the following expression ignoring.

[0008]

(Equation 3)

The terms in parentheses in Equation 3 (V _X t co
_{sA cosB, V Y t sinAcosB,} V Z t
sinB) of the fixed-point operation with the finite bit length
X, ΔY, ΔZ), the calculated phase change amount Δθ
(T) is represented by the following equation.

[0010]

(Equation 4)

The phase compensator 14 corrects the phase of the received digital video signal using the amount of phase change calculated by the phase compensation data generator 10,
To detect 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 performs imaging to display a high-resolution ground map image on the display 18. Can be displayed.

[0012]

In the [0007] conventional radar as described above, the aircraft track 25 as shown in FIG. 8, the speed V = in _{(V X, V Y, V} Z), the angular velocity omega, processable When the vehicle turns around the range 26, there are the following problems. That is, in the conventional apparatus, the calculation of the phase compensation data by the phase compensation data generator 10 is performed by a finite bit length fixed-point operation in order to enable real-time processing, and the operation error increases during turning. Was. That is, assuming that the result of the finite bit length fixed-point operation of each item in parentheses in Equation 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 self-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,
Can be written as K _Z V _Z). When the sum of the calculation error of each term and _{Δe = Δe X + Δe Y +} Δe Z, in the case of the straight line flight, next .DELTA.e _Y ≒ 0 for V _Y ≒ 0, _Δe ≒ _Δe
Because the _X + _{Δe Z,} the allowable error range. Angular velocity ω
And the aircraft is turning, Δe _Y = K _Y V
sin (ωt), so that Δ
Since e increases and exceeds the allowable error λ / 8, it causes image distortion.

In the range walk compensation, the range walk compensator 8 calculates the number of range bins shifted during the observation time on the assumption that the distance change from the target increases linearly. When turning, which does not increase gradually, accurate correction cannot be performed, resulting in degradation of resolution.

Further, when the aircraft 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 is reduced. The processing is performed even in a case where the resolution is insufficient, and an image in which a predetermined resolution is not obtained is displayed.

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

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and stores, in a memory, phase compensation amount error component data and a range walk compensation cycle calculated by a simulation as compared with the related art. By doing
Even when turning, phase compensation and range walk compensation can be performed with high accuracy, and when the synthetic aperture length for the target point is insufficient due to the turn and a predetermined resolution cannot be obtained, processing for the target point is not performed. It is still another object of the present invention to provide a device capable of eliminating a deviation in the positional relationship between the own device and the target point in the azimuth direction in the display.

[0017]

In the radar apparatus according to the present invention, the phase compensation amount error component data obtained by the simulation is stored in a memory, and the speed is calculated based on the own motion data obtained from the inertial platform sensor. When the rate of change of the vector becomes constant, it is detected that the aircraft is in a turning state, and the phase compensation data is calculated by the phase compensation data calculator using the optimal phase compensation amount error component data according to the speed and angular velocity. Is corrected.

Further, by storing the range walk compensation period at the time of turning based on the linear approximation simulation in the memory, even when the amount of change in the distance from the target does not increase linearly, the range of the constant period according to the speed and the angular speed is obtained. Walk compensation is performed.

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

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

[0021]

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

Further, by storing the range walk compensation cycle at the time of turning by the linear approximation simulation in the memory, even if the amount of change in the distance from the target does not increase linearly, the range walk compensation of a fixed cycle can be performed with the minimum error. Can be done with

Further, when a target point enters a range where processing cannot be performed due to a turn, processing for that point can be prevented.

If the azimuth positional relationship between the own device and the target point is deviated from the actual position on the display due to the turn, the current positional relationship between the target and the own device is calculated by activating the own device, and the display unit displays the current position. , The display azimuth can be controlled.

[0025]

[Embodiment 1] FIG. 1 shows an embodiment of the present invention. 1-7, 1
Reference numerals 0 and 14 to 18 are exactly the same as those of the above-mentioned conventional apparatus. 8 in addition to the operation of the conventional range walk compensator,
The range walk compensator 9 to which the range walk compensation period can be input from the outside is in a turning state due to the fact that the rate of change of the speed vector of the self-oscillation data from the inertial platform sensor 7 has become constant. Turning condition detector that detects that
Numeral 11 denotes an error component data memory for storing phase compensation amount error component data calculated by simulation, and 12 denotes a phase compensation data output from the phase compensation data generator 10 using the error component data memory 11. A phase compensation data corrector 13 for correcting a phase compensation amount error component corresponding to the turning condition output from the turning condition detector 9. The phase compensation data corrector 13 calculates a change in distance from a target point during turning by a linear approximation simulation. A compensation cycle data memory for storing the obtained range walk compensation cycle data, 8
Is a range walk compensator that corrects range walk using the compensation period data memory 13 in accordance with the turning condition output from the turning condition detector 9 in addition to the operation of the conventional range walk compensator. When the aircraft turns during the rotation, the synthetic aperture length becomes short due to a change in the axis with respect to the target point, and the target point is out of the processable range. Then, the change of the axis from the coordinate determination in the display coordinate detector 3 to the start of the processing is calculated,
A processing controller 20 that controls not to perform the processing for the point, when the aircraft turns during the mapping, so that the positional relationship between the target point and the own aircraft in the azimuth direction differs between the actual and the display. In addition, the turning condition detector 9
The target point coordinate calculator 21 calculates the change in the axis from the coordinate determination time to the display time in the display coordinate calculator 3 according to the turning condition output from the display coordinate calculator 3. According to the point coordinate data, the positional relationship between the own aircraft and the target point in the azimuth direction is displayed on the display 18.
The display controller 22 controls the time from when the display coordinates are determined to when processing is started and when the display is performed.
And a timing controller set for the target point coordinate calculator 20.

[0026] In the configuration radar apparatus as described above, the turning condition speed detected from the turning condition detector _{9 V = (V X, V} Y, V Z), when the angular velocity ω, the phase compensation Since the amount of phase change calculated by the equation 3 in the data generator 10 is a fixed-point operation, (V _X t co
_{sA cosB, V Y t sinA cosB} , V Z t
sinB), the result of the finite bit length fixed-point operation is (ΔX, ΔY, ΔZ), and the error amount from the true value of the operation result of each term is (Δe _X , Δe _Y , Δe _Z ) = (K _X V _X ,
K _Y V _Y, and K _Z V _Z). Speed V = (V _X , V _Y ,
V _Z ) and the angular velocity ω, when the body 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). Let Δe =
Assuming that 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 approximate error Δr of the square root by Taylor expansion, and is obtained 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. Correction is performed by the following formula in the corrector 12.

[0029]

(Equation 6)

When the aircraft 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 a 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 from 1 to N), and the distance change amount 28 is ΔR (t _n ).

[0033]

(Equation 8)

(A and b are arbitrary real numbers), b is determined so as to minimize Q, and this is defined as K.
8 is approximated by a straight line 29 having a slope K. In this case, the range walk compensation cycle is r / K, where r is the range resolution. This range walk compensation cycle is stored in the compensation cycle data memory 13, and even when the turn does not linearly increase in the distance from the target, the compensation cycle data is stored in accordance with the turning condition detected by the turning condition detector 9. Using the range walk compensation cycle of the memory 13, the range walk compensator 8 performs range walk compensation at regular intervals.

Further, in FIG. 4, when the processable angle range 30 is from θ _MIN to θ _MAX , the time from the display coordinate determination by the display coordinate calculator 3 to the start of the 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 time is ω
Represented by T _1. Assuming that the target point azimuth angle 32 based on the beam directivity angle data from the display coordinate calculator 3 is θ, θ
In the case of -ωT ₁ <θ _MIN or θ-ωT ₁ <θ _MAX , the synthetic aperture length is insufficient and a predetermined resolution cannot be obtained. I do. For example, in FIG. 4, when the target point 24 at the time of display coordinate determination enters a range 33 where processing is not possible, control is performed so that processing is not performed.

In FIG. 5, the display coordinate calculator 3
Target azimuth angle 32 based on beam pointing angle data from
When the time from display coordinate determination to display is set to T ₂ by the timing controller 22, the machine axis change 34 until the display time is represented by ωT ₂ from the angular velocity detected by the turning condition detector 9. . Target point coordinate calculator 20
ΩT ₂ is calculated, and the display controller 21 controls the display 18 so that the display azimuth angle 35 is θ−ωT ₂ .

[0037]

Since the present invention is configured 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 image quality from deteriorating due to an increase in calculation error caused by turning.

Further, even when the amount of change in distance from the target does not increase linearly, linear range walk compensation can be performed with a minimum error by using the compensation cycle data corresponding to the turn, and degradation of resolution can be prevented. it can.

Further, when the angle with the target point changes due to the turning and the processing becomes impossible due to the shortage of the synthetic aperture length, by controlling so as not to perform the processing for the point, an image with poor image quality is obtained. The processing time spent for displaying can be eliminated.

When the azimuth positional relationship between the own aircraft and the target point is displaced on the display due to the turn, a target point coordinate calculator for calculating the azimuth positional relationship with the current target by maneuvering the own aircraft. By controlling the display azimuth angle using the target point coordinate data, it is possible to eliminate a display shift.

[Brief description of the drawings]

FIG. 1 is a diagram showing a radar apparatus 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 illustrating 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 a deviation of a target point azimuth angle between a coordinate determination time and a display time point.

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

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

FIG. 8 is a diagram illustrating a locus of an aircraft with respect to display coordinates.

[Explanation of symbols]

 Reference Signs List 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 slope K 30 Processable range 31 Machine axis change from display coordinate determination to processing start 32 Target point azimuth angle at coordinate determination 33 Processing not possible 35 Display azimuth axis changes to the display from a range 34 displayed coordinate determination

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-160515 (JP, A) JP-A-6-27235 (JP, A) JP-A-4-262286 (JP, A) JP-A-3-302 78686 (JP, A) JP-A-2-99881 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01S 7/00-7/42 G01S 13/00-13/95

Claims (4)

(57) [Claims] 1. A phased array antenna that radiates a transmission wave to a space in a specific direction and receives a reflected wave, a beam controller that controls the beam direction of the phased array antenna by controlling the phase of an array antenna module,
Determining the display coordinates, and a display coordinate calculator for instructing beam pointing angle relative to the beam controller, and exciter for generating a transmission wave, a receiver for converting a received signal into a digital video receiving signal, Based on an inertial platform sensor that detects the radar platform's sway, the own sway data from the inertial platform sensor, and the beam directional angle data from the display coordinate calculator, it is assumed that the distance change from the target surface point is linear. The range walk compensator that calculates the shift cycle of the range bins and shifts the range bins at a fixed cycle interval, and the rate of change of the speed vector becomes constant based on the own motion data from the inertial platform sensor, A turning condition detector that detects that the aircraft is turning and outputs speed and angular velocity; A phase compensation data generator for calculating the amount of phase change of the received signal in real time based on the own-station shaking data from the platform sensor and the beam pointing angle data from the display coordinate calculator, and a phase compensation amount calculated by simulation An error component data memory for storing an error component, and using the error component data memory, the phase compensation data output from the phase compensation data generator according to the turning condition output from the turning condition detector. A phase compensation data corrector for correcting the phase compensation amount error component, a phase compensator for correcting the phase of the received signal using data from the phase compensation data corrector, and a Doppler frequency corresponding to the azimuth direction in the beam. FFT (Fa
(st Fourier Transform) calculator, an amplitude detector for detecting the amplitude of a specific frequency from the data output from the FFT calculator, and an image data converter for converting the data output from the amplitude detector to image data And a display for displaying image data output from the image data converter. 2. The method according to claim 1, wherein the range walk compensator uses the range walk compensation period calculated by a linear approximation simulation to determine the turning condition when the amount of change in the distance from the target point does not increase linearly while the body is turning. 2. The radar apparatus according to claim 1, further comprising a compensation cycle data memory for performing range walk compensation at a fixed cycle interval according to a turning condition output from the detector. 3. A timing controller for setting the time from the determination of the mapping coordinates to the start and display of the processing, a set time from the determination of the coordinates set by the timing controller to the start of the processing, and the display coordinate calculator. And a processing controller that controls not to perform processing on a point that cannot be processed due to the turning of the aircraft during mapping, based on the beam directing angle data and the turning condition output from the turning condition detector. 2. The radar device according to claim 1, wherein: 4. Since a certain time is required from the determination of the mapping coordinates to the execution of the processing, the aircraft turns during the mapping, and the positional relationship between the target point and the own aircraft in the azimuth direction is actually determined. When the display is different from the display, the change of the machine axis from the coordinate determination to the display time is calculated by the turning condition output from the 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 directing angle data from the coordinate calculator to accurately display the positional relationship between the own device and the target point. The radar apparatus according to claim 1, further comprising a display controller that controls the display.