JP2978628B2 - 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 apparatus for improving cross-range resolution by utilizing a Doppler effect caused by movement of a target and a change in a posture angle.

[0002]

2. Description of the Related Art Conventionally, there has been an apparatus of this type as shown in FIG. This figure is disclosed in JP-A-63-05077.
No. 6 discloses this. In the figure, 1 is a transmission / reception antenna, 2 is a transmission / reception switch, 3 is a transmitter, 4 is a receiver, 5 is a range compression unit, 6 is a three-dimensional storage unit (hereinafter referred to as 3D storage unit), and 7 is a motion compensation unit. , 8 are elevation compression means, 10 is azimuth compression means, 11 is 3
Dimensional display buffer (hereinafter referred to as 3D display buffer), 1
2 is a monitor TV.

FIG. 13 is a diagram showing the geometry of a radar device. In the figure, 1 is a transmitting / receiving antenna, and 30 is a center point of a target which goes straight along with a rolling motion.

FIG. 14 is a diagram for explaining the data sampling operation of the radar apparatus. Reference numeral 51 is a sampling chart for elevation compression, and 52 is a sampling chart for azimuth compression.

FIGS. 15 and 16 are views for explaining the movement of the target. In FIG. 15, reference numeral 40 denotes a point separated by re from the target center point 30 in the elevation direction. In FIG. 16, reference numeral 41 denotes a point separated from the center point 30 of the target by ra in the azimuth direction.

Next, the operation of the radar device will be described. Here, the target is moving at a speed V _T in the azimuth direction, the maximum roll angle ± theta] As further shown in FIG. 15
₀ , it is assumed that a rolling motion is performed at a period T ₀ .

First, a high-frequency pulse signal generated by the transmitter 3 is emitted from the transmission / reception antenna 1 to the target via the transmission / reception switch 2. The radar echo reflected by the target is received again by the transmission / reception antenna 1 as a reception signal, and is input to the receiver 4 via the transmission / reception switch 2. The signal amplified and phase-detected by the receiver 4 is input to a range compression unit 5.
, Where processing for improving the range resolution, that is, pulse compression is performed. The received signal after range compression is once recorded in the 3D storage means 6 as two-dimensional data of the range bin number k and the pulse hit number n.

Next, the motion compensating means 7 reads the received signal again, and in order to remove random components from the motion of the target, perform phase compensation so that the Doppler frequency at the target center point 30 becomes zero, and arrange the range bins. Make a change.
Further, as shown in FIG. 14, the received signal is divided in accordance with the target rolling cycle, and is converted into three-dimensional data of a range bin number k, a sampling number 1 for azimuth compression, and a sampling number m for elevation compression. To record. The received signals after such phase compensation and rearrangement are input to the elevation compression means 8 and the azimuth compression means 10, and use the difference in Doppler frequency to
Elevation resolution and azimuth resolution are each improved.

Next, a description will be given of the Doppler effect caused by a change in the target attitude angle, here the roll angle, and the Doppler effect caused by the movement of the target in the azimuth direction.

The target is assumed to be rolling with a period T ₀ and a maximum roll angle ± θ ₀ as shown in FIG. At this time, since the roll angle θ _{R (t)} at time t is given by θ _{R (t)} = θ ₀ SIN (2πt / T ₀ ) (1), the point 40 which is separated from the target center point 30 by a radius re is Doppler frequency fθ _{R (t)} due to the rotation of is calculated by using the transmission wavelength λ, fθ _{R (t)} = 2 / λ · d / dt · [resin θ _{R (t)} ] = 2 / λ · re cos (θ _{R (t)} ) · 2πθ ₀ / T ₀ · cos (2πt / T ₀ ) (2) In this type of radar device, θ _{R (t)} << 1
, Because it is _{t << T 0, fθ R (} t) can be approximated by _{fθ R (t) = 2ry /} λ · 2πθ 0 / T 0 (3). In equation (3), ry is given by ry = re
cos θ _{R (t)} represents the length in the elevation direction. That is, the position ry on the elevation axis can be obtained by measuring the Doppler frequency fθ _{R (t)} . FFT (First Fourier) of the elevation compression means 8
Assuming that the frequency resolution of the transform is Δf, the elevation resolution Δre can achieve Δre = λ / 2 · Δf / (2πθ ₀ / T ₀ ) (4).

Next, since the target is moving at a speed VT in the azimuth direction, the Doppler frequency f _{VT (t) at} a point separated by ra in the azimuth direction from the target center point 30 is determined by the transmission / reception antenna 1 and the center Using the distance R ₀ to the point 30, f _{VT (t)} = 2V _T ra / λR ₀ (5) Therefore, the position ra on the azimuth axis can be obtained by measuring the Doppler frequency _{fVT (t)} . Assuming that the frequency resolution of the FFT of the azimuth compressing means 10 is Δf, the azimuth resolution Δra can achieve the following: Δra = λ / 2 · Δf / (V _T / R ₀ ) (6)

In general, in the application of this type of radar apparatus, since the observation time ΔTe of elevation compression is considered to be sufficiently smaller than the sampling interval Δta of azimuth compression, two cross ranges of elevation compression and azimuth compression are used. Compression processing can be performed simultaneously.

As described above, the signal whose resolution has been increased in the three directions of the range direction, the elevation direction, and the azimuth direction is stored in the 3D display buffer 11, and the composite video signal whose power is proportional to the luminance. And displayed on the monitor TV 12 as a three-dimensional radar image.

[0014]

Since the conventional radar apparatus is configured as described above, a target rolling cycle is estimated, and a data set used for azimuth compression and a data set used for elevation compression are determined. Since the data is divided and stored in the memory, if an error occurs in the estimated value of the target rolling cycle, there is a problem that the performance of the azimuth compression is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a radar apparatus capable of executing azimuth compression without deteriorating performance even if an error occurs in a target rolling cycle estimation value. The purpose is to:

[0016]

A radar apparatus according to a first aspect of the present invention further includes a cycle estimation error compensating means for correcting data based on a target rolling cycle estimation error.

A radar apparatus according to a second aspect of the present invention controls a cycle estimation error compensator for correcting data based on a target rolling cycle estimation error, and controls a plurality of compensation calculations by the cycle estimation error compensator. And a compensation control means for performing the operation.

[0018]

In the first aspect, the cycle estimation error compensating means compensates for the phase error caused by the target rolling cycle estimation error. Therefore, even if an error occurs in the target rolling cycle estimation value, the performance is not degraded. Azimuth compression can be performed.

In the second invention, the cycle estimation error compensating means compensates for a phase error caused by the target rolling cycle estimation error, and the compensation control means controls the cycle estimation error compensating means to compensate for the phase error. Since the repetition is performed, even if an error occurs in the estimated value of the target rolling cycle, the azimuth compression can be performed without deteriorating the performance.

[0020]

【Example】

Embodiment 1 FIG. FIG. 1 is a block diagram showing an embodiment of the present invention, wherein 1 to 8 and 10 to 12 are the same as those of the conventional apparatus shown in FIG. In FIG. 1, reference numeral 9 denotes a fluctuation period estimation error compensating unit 9 for compensating a phase error of a received signal caused by an error in a target rolling period estimation value.
Is a compensation control means for controlling the oscillation period estimation error compensation means 9.

FIG. 2 shows a fluctuation period estimation error compensating means 9.
And FIG. 6 is a functional configuration diagram in which compensation control means 13 is enlarged.
Reference numerals 9 and 13 are the same as those shown in FIG. Here, reference numeral 6 denotes a two-dimensional cross section obtained by cutting the 3D storage means 6 of FIG. 1 at a certain specific range bin.
It is assumed that it has a function of a dimension shift register.
14 is an amplitude normalizing means for normalizing the amplitude of the signal and extracting only the phase information, 19 is a shift register, 20 is a changeover switch for selecting an arbitrary elevation bin from the 3D storage means 6, and 21 is an elevation direction. Computing means for obtaining the amount of phase compensation, 22 is a phase shifter, and 24 is plane selecting means for selecting an arbitrary range bin from the 3D storage means 6 and obtaining an elevation-time plane.

First, the operation of the oscillation period estimation error compensating means 9 and the compensation controlling means 13 will be described with reference to FIG. FIG. 3 shows the positional relationship between the transmitting / receiving antenna and the target. Reference numeral 1 denotes a transmitting / receiving antenna, which is the same as that shown in FIG. 30 is the center point of the target, 31 is the same Azima as the center point 30 of the target
It is on the scan axis, a point which reflects radio waves particularly strongly on the target, which functions as an upset period estimation error compensation reference point. Also, in the figure, T1, T2, T3, T4,... Are each sampling time having a sampling period Δta, E1, E2, E3, E4,. R2, R3,... Indicate range bins. The points 30 and 31 are on the same target, and are linearly moving in the positive direction along the azimuth axis at a speed V with rolling motion. If there is an error in the estimated value of the target rolling period, the azimuth compression sampling timing is not performed at a desired time, and thus the target rolling angle at each sampling time is not constant as shown in FIG.

Therefore, the compensation control means 13 shown in FIG. 2 estimates the range bin and the elevation bin in which the data of the point 31 which reflects the radio wave particularly strongly on the target and operates the plane selecting means 24 and the changeover switch 20 respectively. .
At this time, as the output of the changeover switch 20, signals reflected at points 31 and 34 are obtained. In this example, at time T1, point 31 is at range bin = R2 and elevation = E3, and at time T2, point 34 is also at range bin = R2 and elevation = E3.

The motion compensating means 7 includes the center points 30 and 3 of the target.
3 is compensated so that the phases of the received signals reflected from the point 3 become equal.
And the phase of the signal reflected by the point 34 becomes equal. On the other hand, when there is an error in the period estimation value, the phase difference between the reflection signals at points 31 and 34 is as follows. Assuming that the sampling value of the phase at time t _i is Φ _i , the difference ΔΦ _i between Φ _i and Φ _{i + 1} is the distance R ₁ from the transmitting and receiving antenna at point 34 in FIG. This corresponds to the difference in R ₂ . ΔΦ _i = Φ _i −Φ _{i + 1} = 4π (R ₁ −R ₂ ) / λ (7) where λ is the transmission wavelength.

Therefore, from the phase of the received signal at time t _i , Δ
By subtracting Φ _{i, the} target rolling angle at each sampling time can be equivalently equalized. However, the phase because with ambiguity 2 [pi, to error compensation using this principle, it is necessary to phase error .DELTA..PHI _i caused by the periodic estimate is within the range of ± [pi.

The operation of FIG. 2 will be described based on this principle. [Procedure 1] The compensation control means 13 connects the changeover switch 20 and the plane selection means 24 to the elevation bin and the range bin where the signals received from the points 31 and 34 in FIG. 3 are recorded. Next, a copy of data in the time axis direction is output from the one-dimensional memory at the connected position via the switch 20. The output signal of the changeover switch 20 is input to the amplitude normalizing means 14 and is normalized so that its amplitude becomes 1. In FIG. 2, the data in the time axis direction is Φ
_As shown in FIG. 5, the original data is composed of I and Q complex signals, and the data having the amplitude AC has the amplitude BC, as shown in FIG. At this time, the phase Φ _i
Does not change anything. The data in the time axis direction normalized by the amplitude normalizing means 14 is stored in the shift register 19. Here, when the phase of the reference [Phi _0, the [Phi ₀ is input is shifted to the phase compensation amount calculating means 21, and records the value in the buffer. Then, the reference phase Φ ₀ and Φ ₁ , Φ sequentially sent from the shift register
₂ , Φ ₃ ,..., That is, the phase compensation amount Δ
Φ _i is calculated using equation (7).

[0027] [Step 2] to compensate the received signal recorded in the 3D memory means 6 by using the phase compensation amount .DELTA..PHI _i obtained. First, the shift register 19 shifts one stage at a time in the time direction in synchronization with the 3D storage unit 6. The output data ΔΦ _i of the phase compensation amount calculation means 21 is input to the phase compensation amount calculation means 21 in the elevation direction, and the following calculation is executed. ΔΩ _j = j · ΔΦ _i / EL ₀ (8) where EL ₀ is the elevation bin number of the phase compensation reference points 31 and 34, and j is the number of the elevation bin of interest (J = 0, 1, 2,. .., ELmax, ELmax is the number of elevation bins).

For example, the first phase compensation amount is ΔΦ ₀ =
Φ ₀ −Φ ₀ = 0, and 0 is output from the phase compensation amount calculating means 21. The phase shifter 22 inputs the data at the time T1 from the 3D storage means 6 and generates ΔΦ ₀
To compensate for the data phase at time T1 based on the above equation (8). The compensated data is again 3D
It is stored in the original position of the storage means 6. The second phase compensation amount is ΔΦ ₁ = Φ ₀ −Φ ₁ , and the output from the phase compensation amount calculating means 21 is ΔΦ ₁ Is output. Phase shifter 22 inputs the data at time T2 from the 3D memory means 6, based on the above equation to input ΔΦ ₁ (8),
The data phase at time T2 is compensated. The compensated data is stored again in the original position of the 3D storage means 6. In the same manner, the data at each time Ti compensated by .DELTA..PHI _i. Equation (8) is an operation for obtaining a necessary phase compensation amount according to the target elevation bin position. The compensation amount is zero at the elevation position of the target center point 30, and a larger compensation amount is provided as the distance from the target center point 30 increases. The data output from the 3D storage means 6 by the shift register function is phase-compensated by the phase shifter 22 by the compensation amount ΔΩj corresponding to each elevation position j, and is recorded in the 3D storage means 6 again.

[Procedure 3] Procedure 2 is repeatedly executed for i = 1 to N (N is the number of azimuth compression samplings). By this operation, an error of one-dimensional data in the time axis direction in the 3D storage unit can be compensated.

[Procedure 4] The compensation control means (13) switches the changeover switch 20 and repeats the procedure 3 for all elevation bins. With this operation, data errors can be compensated for one elevation-time plane of the 3D storage means 6.

[Procedure 5] The compensation control means 13 switches the plane selection means 24 and repeats steps 3 and 4 for all range bins. By the operation up to this point, errors of all data in the 3D storage means 6 can be compensated.

[End of Procedure] The above is the description of the operation of FIG. 2 and the operation of the oscillation period estimation error compensating means 9 and the compensation controlling means 13 of FIG.

Next, the operation of FIG. 1 will be described. The high-frequency pulse signal generated by the transmitter 3 is emitted from the transmission / reception antenna 1 to the target via the transmission / reception switch 2. The signal reflected by the target is received by the transmission / reception antenna 1 again, and is input to the receiver 4 via the transmission / reception switch 2. The signal amplified and phase-reduced by the receiver 4 is input to the range compression means 5, where a process for improving the range resolution, that is, pulse compression is performed. The received signal after range compression is
According to the range number k and the pulse hit number n, they are temporarily stored in the 3D storage means 6 as two-dimensional data.

Next, the motion compensating means 7 reads the received signal and removes the phase compensation and rearranges the range bins so that the Doppler frequency of the target center point 30 becomes zero in order to remove random components from the target motion. Perform Further, the target roll cycle is estimated, and the received signal is divided into three dimensions as shown in FIG. 14 for each range bin and stored in the 3D storage means 6.

The elevation compression means 8 reads the data from the 3D storage means 6 and separates the Doppler frequency generated by the target roll by FFT to obtain a target elevation direction shape.

The fluctuation period estimation error compensating means 9 has a function of compensating for the period estimation error of the target roll. The compensation control means 13 has a function of controlling the operation of the oscillation period estimation error compensation means 9. These operations have been described above.

The azimuth compression means 10 performs azimuth compression using the Doppler frequency generated by the linear motion to obtain a target shape in the front-rear direction. The obtained three-dimensional shape of the target is stored in the 3D display buffer 11 and displayed on the monitor television 12. Therefore, even when the cycle of the target roll cannot be accurately estimated, the azimuth compression can be executed without deteriorating the performance.

Embodiment 2 FIG. In the first embodiment, the case where the number of the points 31 for reflecting the radio wave is one is shown. However, as shown in FIG.
However, as shown in 31a and 32b, there may be two points (or more). However, as described above, in order to perform error compensation, the phase error ΔΦ _i caused by the cycle estimation value needs to be within the range of ± π,
For example, when the transmission wavelength λ is 3 cm, Δr needs to be 1.5 cm or less as shown in FIG. It is more accurate to perform the phase compensation at a point where the elevation is as far away from the target center 30 as possible. However, due to the limitation of the transmission wavelength (restriction of ± π), the phase compensation is performed in order from the center 30 of the target. It will be performed. For example, performs a first phase compensation at point 31a, then performs a phase compensation at point 31b, it <br/> to perform phase compensation using a point moving away in order.

Embodiment 3 FIG. In the first and second embodiments, the case where the target center point 30 and the point 31 for reflecting the radio wave are on the same azimuth axis has been described. The case where the point 31 is on a different azimuth axis will be described.

FIG. 7 is a block diagram showing an embodiment of the present invention, wherein 1 to 8 and 10 to 12 are the same as the conventional apparatus shown in FIG. In FIG. 7, reference numeral 9 denotes a fluctuation period estimation error compensating means for compensating a phase error of a received signal caused by an error of a target rolling period estimation value;
Numeral 3 denotes compensation control means for controlling the repetition of the oscillation period estimation error compensation means 9. FIG. 8 is an enlarged functional block diagram of the oscillation period estimation error compensating means 9 and the compensation control means 13, and 6, 9 and 13 are the same as those shown in FIG. Here, reference numeral 6 denotes a two-dimensional cross section obtained by cutting the 3D storage means 6 of FIG. 7 at a specific range bin, and has a function of a two-dimensional shift register in the time axis direction. 14 is an amplitude normalizing means for normalizing the amplitude of the signal to extract only phase information, 15 is a one-dimensional storage means used for storing a one-dimensional data sequence, and 16 and 22
Is a phase shifter, 17 is a calculating means for obtaining a phase compensation amount in the time axis direction, 18 is a phase change rate calculating means, 19 is a shift register, 20 is a changeover switch for selecting an arbitrary elevation bin from the 3D storage means 6, 21 is a calculating means for calculating the amount of phase compensation in the elevation direction, and 24 is a means for selecting an arbitrary range bin from the 3D storage means 6 and raising the elevation bin.
This is plane selection means for obtaining a time plane. First, the operation of the oscillation period estimation error compensating means 9 and the compensation control means 13 will be described with reference to FIG. FIG. 9 shows the positional relationship between the transmitting / receiving antenna and the target. Reference numeral 1 denotes a transmitting / receiving antenna, which is the same as that shown in FIG. 30 is the center point of the target, 31, 3
Numeral 2 is a point on the azimuth axis different from the center point 30 of the target, and reflects a radio wave particularly strongly on the target, and functions as a reference point for compensating for a fluctuation period estimation error. Note that point 3
0, 31, and 32 are all on the same target, and point 31 has a lower (smaller) elevation than point 32
Suppose that it is linearly moving in the positive direction along the azimuth axis at a speed V with rolling motion. If there is an error in the estimated value of the target rolling period, the azimuth compression sampling timing is not performed at the desired time, and therefore the target rolling angle at each sampling time is not constant as shown in FIGS. . Therefore, the compensation control unit 13 in FIG. 8 estimates the range bin and the elevation bin in which the data of the points 31 and 34 where the radio wave is reflected particularly strongly on the target having the smaller elevation, and estimates the range bin and the elevation bin. 20 are operated respectively. At this time, as the output of the changeover switch 20, signals reflected at points 31 and 34 are obtained.

FIG. 10 shows points 30, 31, 32 and 3
It is a figure which shows the relationship of 3, 34, 35, and as shown in FIG.
Considering the case where the distances Rb and Re are equal to a to Rf, the distances Ra and Rd between the points 31 and 34 are Ra> Rd.
It becomes the relationship. Similarly, the distance R between the point 32 and the point 35
c and Rf have a relationship of Rc < Rf.

Assuming that the movement in the Asias direction is eliminated as shown in FIG. 10B, it is considered that the point 31 moves to the point 34 and the point 32 moves to the point 35, respectively, as yaw movements. be able to. Therefore, as shown in FIG. 10C, the points 31 and 32 have a rolling motion X centered on the Asians axis (AZ) and a yaw motion Y centered on the target center point 30. .

FIG. 11 shows the phase of the output signal of the changeover switch 20 with respect to the time axis. 38 is an eye
This is the phase change of the echo at the center points 30 and 33 of the target . 36
Represents a phase change when there is no error in the estimated value of the rolling period of the yaw motion Y at the points 31 and 34 . Reference numeral 37 denotes a phase at each sampling time when the target performs the X rolling motion and the Y yaw motion, and an error occurs in the estimated value of the period. Time change 36 of phase when there is no error
Is assumed to be α, the phase Φ (ti) at time ti is given by the following equation. Φ (ti) = αt _i (9) If there is an error, assuming that the sampling value of the phase at time t _i is Φ _i , the difference ΔΦ _i between Φ _i and Φ (ti) is This corresponds to the difference between the distances R ₁ and R ₂ from the transmitting and receiving antennas. ΔΦ _i = Φ _i −Φ (ti) = Φ _i −αt _i = 4π (R ₁ −R ₂ ) / λ (10) where λ is the transmission wavelength. Therefore, by subtracting ΔΦ _i from the phase of the received signal at time t _i , the target rolling angle at each sampling time can be equivalently equalized. However, since the phase has an ambiguity of ± π, the phase error caused by the cycle estimation error must be within this range. However, for that purpose, it is necessary to estimate the inclination α of the straight line 36 in FIG. As can be seen from FIG. 11, if the rolling cycle estimation error is small to some extent, the slope α can be obtained by an operation such as approximation of a linear function from the phase sampling value Φ _{i including} the error. For example, rolling motion cycle estimation error
If the phase error of the received signal caused by the above satisfies the following condition, α can be estimated with probability β using FFT.

(1) When the phase error follows a Gaussian distribution: PS = 10log [−ln (1-β1 ^{/ n} ) −2 / ln (1-β1 ^{/ n} ) +1] + ΔS <−3 [dB] (11) ΔS = 10log [{exp (σ _s ² ) -1} / N] (12) where N: number of sampling points for azimuth compression σ _s : standard deviation of phase error at period estimation error compensation reference point [rad] Σ _s = 4πL _pe ω ₀ σ _t / λ (13) where σ _t : standard deviation of rolling period estimation error [sec] L _pe : elevation coordinate of period estimation error compensation reference point P
[m] ω ₀ : target rolling angular velocity [rad / sec] λ: radar transmission wavelength [m] and n = vΔta / λ (14) v: target straight traveling velocity [m / sec] Δta: azimuth sampling interval [sec]

(2) When the phase error follows a uniform distribution: PS = 10 log [−ln (1-β ^{1 / n} ) −2 / ln (1−β ^{1 / n} ) +1] + ΔS <−3 [dB] (15) ΔS = −10log [N {(12 / Δφ ² ) −1}] (16) where Δφ is the maximum value of the phase error at the period estimation error compensation reference point P [rad] and Δφ = 4πL _pe ω ₀ dτ / λ (17) where dτ: maximum value of the rolling cycle estimation error [sec]

When this condition is satisfied, the power of the frequency corresponding to α in the output of the FFT is at a level higher than the peak of the other side lobe by 3 dB or more, so that α can be correctly estimated.

The operation of FIG. 8 will be described using this principle. [Procedure 1] The compensation control means 13 connects the changeover switch 20 and the plane selecting means 24 to the elevation bin and the range bin where the signals received from the points 31 and 34 in FIG. 9 are recorded. Next, a copy of data in the time axis direction is output from the one-dimensional memory at the connected position via the switch 20. The output signal of the changeover switch 20 is divided into two. One is stored in the one-dimensional storage means 15 via the amplitude normalization means 14 in order to extract only the phase information. On the other hand, the inclination α of the phase change straight line 36 is obtained by the phase change rate calculating means 18 and is input to the phase compensation amount calculating means 17 in the time axis direction. Here, the phase compensation amount calculation means 17 calculates each sampling time t using equation (10).
and calculates a phase compensation quantity .DELTA..PHI _i outputs in _i. The phase of the data in the one-dimensional storage means 15 is compensated by the phase shifter 16 by the compensation amount ΔΦ _i corresponding to the time t _i , and is recorded in the shift register 19. By the above operation, the phase compensation reference point 34 caused by the error in estimating the rolling period
Are obtained for compensating for the phase error of the above, and are recorded in the shift register 19.

[0048] [Step 2] to compensate the received signal recorded in the 3D memory means 6 by using the phase compensation amount .DELTA..PHI _i obtained. First, the shift register 19 shifts one stage at a time in the time direction in synchronization with the 3D storage unit 6. The output data ΔΦ _i of the shift register 19 is
It is input to the elevation direction phase compensation amount calculation means 21 and the following calculation is performed. Ωij = j · ΔΦ _i / EL ₀ (18) where EL ₀ is the elevation bin number of the phase compensation reference points 31 and 34, and j is the number of the elevation bin of interest (J = 0, 1, 2,...). ., ELmax, ELmax is the number of elevation bins). Equation (18) is an operation for obtaining a necessary phase compensation amount according to the target elevation bin position. The compensation amount is zero at the elevation position of the target center point 30, and a larger compensation amount is provided as the distance from the target center bin 30 increases. The data output from the 3D storage means 6 by the shift register function is phase- compensated by the phase shifter 22 by the compensation amount ΔΩij corresponding to each elevation position j, and is recorded in the 3D storage means 6 again.

[Procedure 3] Procedure 2 is repeatedly executed for i = 1 to N (N is the number of azimuth compression samplings).
By this operation, an error of one-dimensional data in the time axis direction in the 3D storage unit can be compensated.

[Procedure 4] The compensation control means 13 switches the changeover switch 20 and repeats the procedure 3 for all elevation bins. With this operation, data errors can be compensated for one elevation-time plane of the 3D storage means 6.

[Procedure 5] The compensation control means 13 switches the plane selection means 24 and repeats the procedures 3 and 4 for all range bins. By the operations up to this point, errors of all data in the 3D storage means 6 can be compensated for once.

[Procedure 6] Subsequently, error compensation is performed with higher accuracy. The compensation control means 13 switches the changeover switch 20 to the elevation bin in which the phase compensation reference points 32 and 35 at the elevation positions higher than the points 31 and 34 and repeats the operations of the procedures 1 to 5. . As a phase compensation reference point, a point having a lower elevation position is selected first, and then a point having a higher elevation position is selected, so that a larger error can be obtained as compared with the case where one phase compensation reference point is used. Compensation can be performed with high accuracy.

[Step 7] Step 6 is repeated for all points that can be used as phase compensation reference points on the target.

[End of Procedure] The above is the description of the operation of FIG. 8, and the operation of the oscillation period estimation error compensating means 9 and the compensation controlling means 13 of FIG.

Next, the operation of FIG. 7 will be described. The high-frequency pulse signal generated by the transmitter 3 is emitted from the transmission / reception antenna 1 to the target via the transmission / reception switch 2. The signal reflected by the target is received by the transmission / reception antenna 1 again, and is input to the receiver 4 via the transmission / reception switch 2. The signal amplified and phase-reduced by the receiver 4 is input to the range compression means 5, where a process for improving the range resolution, that is, pulse compression is performed. The received signal after range compression is
According to the range number k and the pulse hit number n, they are temporarily stored in the 3D storage means 6 as two-dimensional data. Next, the motion compensating means 7 reads the received signal and removes the target center point 3 in order to remove random components from the target motion.
Phase compensation and rearrangement of range bins are performed so that the Doppler frequency of 0 becomes zero. Further, the target roll cycle is estimated, and the received signal is divided into three dimensions as shown in FIG. 14 for each range bin and stored in the 3D storage means 6. The elevation compression means 8 reads the data from the 3D storage means 6, separates the Doppler frequency generated by the target roll by FFT, and obtains the target elevation direction shape. The oscillation period estimation error compensating means 9 has a function of compensating for the period estimation error of the target roll. The compensation control means 13 has a function of controlling the operation of the oscillation period estimation error compensation means 9. These operations have been described above. The azimuth compression means 10 performs azimuth compression using the Doppler frequency generated by the linear motion, and obtains a target shape in the front-rear direction. The obtained three-dimensional shape of the target is stored in the 3D display buffer 11 and displayed on the monitor television 12. Therefore, even when the cycle of the target roll cannot be accurately estimated, the azimuth compression can be executed without deteriorating the performance.

Embodiment 4 FIG. In the above embodiment, the case where two points (31, 32) for reflecting the radio wave are used is described, but the case where only one point is used may be used. In this case, the repetition of steps 6 and 7 is omitted. Also, two or more points may be performed, and in this case, the operations of steps 1 to 5 are repeated a plurality of times by steps 6 and 7.

[0057]

As described above, according to the first aspect of the present invention, a period estimation error compensating means for correcting the estimation error of the target rolling period is added. If present, there is an effect that azimuth compression can be executed without deteriorating performance even when the target rolling motion cycle cannot be accurately estimated.

According to the second aspect of the present invention, a cycle estimation error compensating means for correcting a target rolling cycle estimation error and a compensation control means for controlling a plurality of compensation calculations are added . If there are two or more parts on the target that reflect the electric wave particularly strongly even on different azimuth axes, the azimuth compression can be performed without deteriorating the performance even when the rolling motion cycle of the target cannot be accurately estimated. The effect is that it can be executed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a functional configuration diagram for explaining in detail the operation of a period estimation error compensating means according to the present invention;

FIG. 3 is an explanatory diagram showing a positional relationship between a target and a transmitting / receiving antenna in the present invention.

FIG. 4 is an explanatory diagram showing a positional relationship between a target and a transmitting / receiving antenna in the present invention.

FIG. 5 is a view for explaining the operation of the amplitude normalizing means of the present invention.

FIG. 6 is a diagram for explaining the operation of the compensation control means of the present invention.

FIG. 7 is a block diagram showing an embodiment of the present invention.

FIG. 8 is a functional configuration diagram for explaining in detail the operation of the period estimation error compensating means of the present invention.

FIG. 9 is an explanatory diagram showing a positional relationship between a target and a transmitting / receiving antenna in the present invention.

FIG. 10 is a view for explaining a yaw movement .

FIG. 11 is an explanatory diagram showing a time change of a phase of a received signal.

FIG. 12 is a block diagram showing a conventional radar apparatus.

FIG. 13 is an explanatory diagram showing a positional relationship between a target and a transmitting / receiving antenna.

FIG. 14 is an explanatory diagram showing sampling rates of azimuth compression and elevation compression in the radar receiver.

FIG. 15 is an explanatory diagram showing a rolling motion of a target.

FIG. 16 is an explanatory diagram showing a linear motion of a target.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Transmission / reception antenna 2 Transmission / reception switch 3 Transmitter 4 Receiver 5 Range compression means 6 3D storage means 7 Motion compensation means 8 Elevation compression means 9 Fluctuation cycle estimation error compensation means 10 Azimuth compression means 11 3D display buffer 12 Monitor television 13 Compensation control means 14 Amplitude normalization means 15 One-dimensional storage means 16 Phase shifter 17 Phase compensation amount calculation means in time axis direction 18 Phase change rate calculation means 19 Shift register 20 Select an arbitrary elevation bin from 3D storage means 6 Switch 21 for performing the operation 21 means for calculating the amount of phase compensation in the elevation direction 22 phase shifter 24 plane selecting means for selecting an elevation-time plane for an arbitrary range bin from the 3D storage means 6 30, 33 target center Points 31, 32, 34, 35 Stronger radio waves on the target The point of reflection, that is, the fluctuation period estimation error compensation reference point 36 The phase change of the received signal from the points 31 and 34 on the target in the output of the elevation compression means 8 when no estimation error occurs in the target rolling period 37 Point 3 on the target in the output of elevation compression means 8 when an estimation error occurs in the rolling cycle
Sampling value of the phase of the received signal from 1, 34 40 A point existing on the target at a distance from the center point 30 in the elevation direction 41 A point existing on the target at a distance from the center point 30 in the azimuth direction 51 Elevation compression Sampling chart 52 Sampling chart of azimuth compression

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masafumi Iwamoto 5-1-1, Ofuna, Kamakura City Mitsubishi Electric Corporation Inside Electronic Systems Laboratory (72) Inventor Takahiko Fujisaka 5-1-1, Ofuna, Kamakura City Mitsubishi Electric Inside the Electronic Systems Laboratory, Inc. (72) Inventor Yoshimasa Ohashi 5-1-1, Ofuna, Kamakura-shi Inside the Electronic Systems Laboratory, Mitsubishi Electric Corporation (56) References JP-A-62-231188 (JP, A) JP 4-5155 (JP, B2) JP 4-5156 (JP, B2) JP 4-5157 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01S 13 / 89-13/90

Claims (2)

(57) [Claims] 1. A radar apparatus utilizing the Doppler effect caused by a movement of a target and a change in a posture angle, wherein a data storage means for storing data obtained from a predetermined point of the target, and a time change of a phase of a received signal. A radar apparatus comprising: a period estimation error compensating unit that corrects data stored in a data storage unit based on an estimated period estimation error of a change in attitude angle of a target. 2. The radar apparatus according to claim 1, further comprising: a compensation control unit that performs the correction by the period estimation error compensating unit a plurality of times in a predetermined order based on data obtained from a plurality of target points. The radar device according to claim 1, wherein: