JP3197217B2 - Radar target angle measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a radar target angle measuring device for obtaining azimuth information and altitude information when acquiring target three-dimensional position information by a radar device having a phased array antenna.

[0002]

2. Description of the Related Art In the prior art, a predetermined reception beam is formed irrespective of the position and altitude of a target, and angles of elevation and azimuth planes are measured. However, this is not always the case that the formed reception beam is suitable for the target, and the measurement accuracy is limited.

In particular, in an environment where a reflected wave from a target directly arrives at the antenna and a reflected wave from the target reflected on the sea surface or the like and then arrives at the antenna after reflection, the angle accuracy is reduced. In order to improve the angle, it is necessary to measure the angle while suppressing the sea surface reflected wave which is an unnecessary signal,
The angle measurement with the preset receiving beam cannot sufficiently suppress the sea surface reflected wave which is the unnecessary signal.

[0004]

As described above, in the conventional radar target angle measuring device, since the reception beam can be formed only in a predetermined direction and shape, the reception beam does not always perform the target angle measurement. However, it is not always suitable for the measurement, and the measurement accuracy is limited. In particular, when there is an unnecessary signal such as a sea surface reflected wave, it is difficult to form a reception beam that sufficiently suppresses the unnecessary signal, and the measurement accuracy has to be reduced.

The present invention solves the above-mentioned problems, and can easily form a reception beam suitable for a target, and can surely suppress unnecessary signals, thereby contributing to improvement of measurement accuracy. It is an object of the present invention to provide a radar target angle measuring device that can perform the measurement.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and achieve the object, the present invention is configured as follows. (1) A radar target angle measuring device used in a radar device having a phased array antenna having a plurality of element elements and measuring an angle in an azimuth direction and an elevation direction of an arbitrary target from a reception output thereof. Receiving signal recording means for recording the received signals of the respective elements over a certain period of time, and using a received signal of each element element recorded by this means to form a plurality of types of received beams at different angles from each other by digital beam forming. A plurality of beams are formed, and while evaluating the influence of unnecessary signals other than the target signal with each reception beam, a reception beam that minimizes the influence of the unnecessary signal is re-formed and the beam angle is measured as a target angle. It is configured to include forming and angle measuring means.

(2) In the configuration of (1), the receiving beam forming / measuring means converts the three types of a pencil beam, an amplitude comparison angle measuring beam, and a phase monopulse beam into a digital beam in the angle measurement of the elevation plane. It was configured to include means for forming by forming.

(3) In the configuration of (2), the receiving beam forming and angle measuring means estimates and estimates the variation of the receiving beam directivity angle and the output value of the amplitude comparison angle measuring beam in the angle measurement of the elevation plane. The apparatus is provided with means for evaluating the influence of the unnecessary signal from the relationship with the elevation angle.

(4) In the configuration of (2), the reception beam forming / measuring means performs, during the processing, the re-forming of the reception beam which minimizes the influence of the unnecessary signal in the angle measurement of the elevation plane. The apparatus is provided with means for selecting and using an obtained angle measurement value from an amplitude comparison angle measurement beam and a phase monopulse angle measurement beam.

(5) In the configuration of (1), the reception beam forming / measuring means forms a plurality of reception beams having different angles from each other on an elevation plane and an azimuth plane, so that the influence of unnecessary signals is minimized. The elevation beam angle measuring means and the azimuth angle measuring means for measuring the beam angle as a target angle, and further based on the angle measurement value obtained by the elevation angle measuring means. The azimuth angle measuring means is provided with a means for re-forming the reception beam.

(6) In the configuration of (1), the reception beam forming / measuring means forms a plurality of reception beams having different angles from each other on an elevation plane and an azimuth plane to minimize the influence of unnecessary signals. Re-formed receiving beam, comprising an elevation angle measuring means and an azimuth angle measuring means for measuring the angle of the beam as a target angle, further based on the angle measurement value obtained by the azimuth angle measuring means The apparatus is provided with means for re-forming the reception beam of the elevation plane angle measuring means.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. In FIG. 1, a receiving device 1
1 receives a radar wave received by each element element of a phased array antenna (not shown) used in the radar apparatus, and an element signal memory device 13 receives
Are received and recorded until the target detection processing in the target detection device 12 is completed and data necessary for angle measurement is read out.

The target detecting device 12 receives the received signals of the respective elements from the receiving device 11, synthesizes a target detecting beam, detects a target, and outputs distance information of the target. The target distance information output from the target detection device 12 is input to the element signal memory device 13, and the signal of each detected reception element of the detected target is extracted and input to the Az synthesis processing device 14.

The Az combining processor 14 performs a beam combining process on the azimuth plane of the received signal of each element. If the azimuth information is obtained in advance, the combining process may be performed using the azimuth information. The result of the synthesis processing obtained here is transmitted to the pencil beam angle measuring device 15 and the amplitude comparison angle measuring device 1.
6. Input to the phase monopulse angle measuring device 19.

The pencil beam angle measuring device 15 forms a large number of pencil beams within the angle range specified by the distance-to-angle table set in advance from the target distance information from the target detection device 12 and has a maximum amplitude. Is selected, and its elevation angle direction is output as the approximate elevation angle. The approximate elevation angle obtained here is input to the amplitude comparison angle measurement device 16.

The amplitude comparison and angle measurement device 16 forms a plurality of amplitude comparison and angle measurement beams using the element reception signal output from the element signal memory device 13 around the input approximate elevation angle. The angle measurement value and the amplitude value are calculated. The angle measurement values and amplitude values of the plurality of beams obtained here are input to the convergence determination device 17.

The convergence judging device 17 judges the influence of the unnecessary signal from the angle measurement values and the amplitude values of the plurality of beams from the amplitude comparison angle measuring device 16 based on a judgment criterion set in advance. Select the angle measurement value of the beam that becomes The angle measurement value selected here is supplied to the terminal 1 of the switch 22 and is also input to the accuracy determination device 18 and the phase monopulse angle measurement device 19.

In the convergence determination device 17, the selected angle measurement value is sent back to the amplitude comparison angle measurement device 16 as an approximate elevation angle until the influence of the unnecessary signal becomes equal to or less than a desired value.
The amplitude comparison angle measurement process may be repeated.

The phase monopulse angle measuring device 19 uses the angle measurement value output from the convergence judging device 18 to calculate the Az combining processing device 14
A mono-pulse beam is formed from the output of, and a phase mono-pulse angle measurement process is performed. The angle measurement value obtained here is supplied to the terminal 0 of the switch 22.

The accuracy determining unit 18 inputs target distance information and a predetermined criterion together with the angle measurement value, and performs amplitude comparison angle measurement processing and phase monopulse angle measurement based on the given target distance and angle measurement value. It is determined which of the processes is higher in accuracy. However, it is not necessary to directly compare the accuracy of each process.
For example, a situation where unnecessary signals are assumed based on the target distance and altitude
Below, the amplitude comparison angle measurement for each target distance
An angle measurement range that gives higher accuracy angle measurement values than angles
In this angle measurement range, the amplitude comparison angle measurement
Accuracy can be determined based on whether or not an angle measurement value is included.
FIG. 1 shows the flow of processing in this case. When it is determined that the amplitude comparison and angle measurement processing gives higher accuracy, the switch 22 is controlled to be switched to the terminal 1 side, and the output of the convergence determination device 17 is output as the elevation angle measurement value of the present device. The monopulse angle measurement control outputs the output of the phase monopulse angle measurement device 19 as an elevation angle measurement value of the present device.

The ΣΔ beam combiner 20 receives the received signals of the respective elements from the element signal memory device 13 and
A sum signal (Σ beam) and a difference signal (Δ beam) directed to the target are formed on the elevation plane of the angle measurement value selected by 7.
If no angle measurement value is obtained, a sum signal and a difference signal directed in a preset elevation direction may be formed. The obtained sum signal and difference signal are input to the ΣΔ phase monopulse angle measuring device 21.

The ΣΔ phase monopulse angle measuring device 21 performs a phase monopulse angle measuring process on the azimuth plane using the input sum signal and difference signal, and outputs an azimuth plane angle measurement value. This azimuth plane angle measurement value is, as described above, the Az synthesis processing device 1
By inputting the value to No. 4, it can also be used for beam combining processing.

The processing operation of the above configuration will be described below with reference to FIGS. In this apparatus, in order to improve the accuracy, the mutual output is used between the calculation of the angle measurement value of the elevation plane and the calculation of the angle measurement value of the azimuth plane . At this time, which value to use depends on the antenna configuration of the radar,
The setting can be made according to a request for the system capability of the radar device.

For the sake of simplicity, the description will be made on the assumption that the antenna elements are arranged in a vertical plane as shown in FIG. In this case, priority is given to calculating the angle measurement value of the elevation plane.

First, the Az synthesis processing device 14 adds the received signals of the respective element elements arranged in the Az direction,
It outputs to the pencil beam angle measuring device 15, the amplitude comparison angle measuring device 16 and the phase monopulse angle measuring device 19.

The pencil beam angle measuring device 15 receives the target distance information from the target detecting device 12, and as shown in FIG. 3, a distance-to-angle table (radar coverage altitude is determined according to the distance) as given in advance. Therefore, a large number of pencil beams are formed in the elevation plane range specified by the distance. The pencil beam formed here is formed in a preset number or in preset angle increments.

In the angle measuring device 15, the reception levels of a large number of pencil beams formed as described above are viewed in order from the top to the bottom, and the beam having the maximum value is detected first, and the detection is performed. The elevation angle of the beam is output as an approximate elevation angle. This is because, as shown in FIG. 4, when the sea surface reflected wave which is an unnecessary signal is affected, the beam on the upper side is less affected by the sea surface reflected wave.

The approximate elevation angle obtained here is input to the amplitude comparison angle measurement device 16. In this amplitude comparison angle measuring device 16,
As shown in FIG. 5A, a plurality of amplitude comparison beams covering an angle range set in advance around a general elevation angle are formed. Then, amplitude comparison angle measurement processing is performed using a plurality of amplitude comparison beams, and each angle measurement value and amplitude value are output. Here, the amplitude value is the output of the upper beam of the amplitude comparison angle measuring beam shown in FIG. 5B.

The angle measurement value and the amplitude value output from the amplitude comparison angle measurement device 16 are input to the convergence determination device 17 and select the angle measurement value that minimizes the influence of the sea surface reflected wave which is an unnecessary signal.
This situation is shown in FIGS. FIG. 6A shows the relationship between the elevation angle and the amplitude value, and FIG. 6B shows the relationship between the elevation angle and the angle measurement value. The elevation angles A to D shown in FIGS. 6A and 6B represent the elevation angles of the beam directing directions shown in FIGS. 7A to 7D.

FIG. 7A shows a state in which the amplitude comparison beam is directed at a high elevation angle, and only a part of the direct wave from the target T is received. At this time, since sufficient reception intensity cannot be obtained, the accuracy of the angle measurement value is not good. In FIG. 7B, the amplitude comparison beam is directed in the direction of the direct wave. FIG.
(C) shows an amplitude comparison beam directed at a lower elevation angle, and shows a state in which a part of the direct wave and a part of the sea surface reflected wave are received together. FIG. 7D shows a state in which the amplitude comparison beam is further directed at a lower elevation angle, and mainly the sea surface reflected wave is received.

As shown in FIG. 6A, since only a part of the direct wave is received at A, the amplitude value is small and does not reach the threshold value. In B, the amplitude value is equal to or larger than the threshold. In C, since the sea surface reflected wave starts to be further received by the direct wave, the amplitude value increases as shown by a solid line in FIG. Decrease as shown. The angle measurement value shifts to the low elevation angle side as shown in FIG. 6B as the influence of the sea surface reflected wave increases.

The convergence judging device 17 outputs a condition (angle measurement value, amplitude value) satisfying the following conditions by using the above features. Amplitude value> threshold value 1 threshold value 2> | δ angle measurement value / δ angle | Here, the threshold value 1 is, for example, a threshold value indicated by a dotted line in FIG.
Means that only amplitude values exceeding this threshold 1 are extracted
Will be done. The threshold value 2 is a basis of the rate of change of the angle measurement value.
It is a quasi-comparison value, and the rate of change is, for example, as shown in FIG.
Corresponding to the rate of change in the angle measurement value at each elevation angle A to D
You. That is, here, the angle measurement of the change rate less than the threshold value 2
Only the values will be extracted. The thresholds 1 and 2 are input to the convergence determination device 17 as determination conditions. If the determination here is not satisfied with the output of the amplitude value comparison angle measurement device 16, the angle measurement value that satisfies the most conditions is sent back to the amplitude comparison angle measurement device 16 as an approximate elevation angle, and the amplitude comparison angle measurement process is performed. May be repeated.

The accuracy judging device 18 receives the output of the convergence judging device 17 and the target distance information, compares it with a judgment criterion given in advance, and outputs a switching control signal corresponding to the comparison result to the switch 22.

The determination criterion here is that the amplitude comparison angle measurement is different from the phase monopulse angle measurement for each target distance under the situation where the presence of a sea surface reflected wave as an unnecessary signal is assumed from the target distance and altitude. FIG. 9 shows an angle measurement range that provides an angle measurement value with higher accuracy. That is, in the accuracy determination device 18, when the input angle measurement value is within this range, the switch 22
To the terminal 1 side. In other cases, that is, when the phase monopulse angle measurement has an angle measurement range that provides higher accuracy, the switch 2
2 is switched to the terminal 0 side.

The phase monopulse angle measuring device 19 receives the angle measurement value output from the convergence judging device 17 and the output of the Az synthesizing device 14, forms an optimal phase monopulse beam in the elevation direction indicated by the angle measurement value, and forms a phase monopulse beam. Performs monopulse angle measurement.

On the other hand, the .SIGMA..DELTA. Beam forming apparatus 20 uses the input angle measurement value in the azimuth direction in which the target is directed on the elevation plane so that good sensitivity can be obtained in the phase monopulse angle measuring apparatus 21 at the subsequent stage. A sum signal (Σ beam) and a difference signal (Δ beam) are formed. The ΣΔ phase monopulse angle measuring device 21 performs a phase monopulse process using the azimuth direction sum signal and difference signal obtained by the ΣΔ beamformer 20 as inputs. As a result, an azimuth angle measurement value is obtained.

Therefore, the radar target angle measuring device having the above configuration can form an angle measuring beam linked to the target distance and altitude, so that it can be used in a conventional radar using a fixed type angle measuring beam. In comparison, even in a situation where there is an unnecessary signal such as a sea surface reflected wave, highly accurate angle measurement is possible.

In the above embodiment, the elevation angle measurement is performed first, and the azimuth angle measurement is performed using the result. However, as shown by the dotted line in FIG. For example, the direction angle measurement may be performed first and the result may be reflected.

[0039]

As described above, according to the present invention, a receiving beam suitable for a target can be easily formed, and unnecessary signals can be surely suppressed, thereby contributing to improvement of measurement accuracy. And a radar target angle measuring device capable of performing the measurement.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a radar target angle measuring device according to the present invention.

FIG. 2 is an exemplary perspective view showing an antenna shape of a phased array antenna for a radar device used as an example in the description of the embodiment;

FIG. 3 is a diagram showing that a distance-to-angle table used in the pencil beam angle measurement processing of the embodiment determines an elevation plane range from a target distance from a radar coverage altitude.

FIG. 4 is an exemplary view showing a geometric relationship between a sea surface reflected wave as an unnecessary signal and a direct wave from a target, which is given as an example in the description of the embodiment;

FIG. 5 is a view showing a state in which an amplitude comparison angle measurement beam is formed around the approximate altitude obtained in the pencil beam angle measurement processing in the amplitude comparison angle measurement processing of the embodiment.

FIG. 6 is a view showing the relationship between the elevation angle and the amplitude value, and the relationship between the elevation angle and the angle measurement value used for explaining the behavior of the angle measurement value and the amplitude value input to the convergence determination device of the embodiment according to the elevation angle.

FIG. 7 is a diagram illustrating a state of a reception beam corresponding to elevation angles A to D in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Receiving device 12 ... Target detection device 13 ... Element signal memory device 14 ... Az synthesis processing device 15 ... Pencil beam angle measuring device 16 ... Amplitude comparison angle measuring device 17 ... Convergence judgment device 18 ... Accuracy judgment device 19 ... Phase monopulse measurement Angle device 20: ΣΔ beam combining device 21: ΣΔ phase monopulse angle measuring device 22: Switch

Continuation of front page (56) References JP-A-4-323586 (JP, A) JP-A-7-280918 (JP, A) JP-A-6-59030 (JP, A) JP-A-5-150037 (JP) , A) JP-A-1-297579 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S ⁷ /00-7/42 G01S 13/00-13/96

Claims (6)

(57) [Claims] 1. A radar target angle measuring device for use in a radar device having a phased array antenna having a plurality of element elements and measuring an azimuth direction and an elevation angle of an arbitrary target from a reception output thereof. Receiving signal recording means for recording the received signal of each of the element elements over a certain period of time; and using the received signal of each element element recorded by this means to form a plurality of types of received beams by digital beam forming. While forming multiple at different angles, while evaluating the influence of unnecessary signals other than the target signal with each receive beam,
Reshape the receive beam to minimize the effects of unwanted signals,
A radar target angle measuring device comprising: a receiving beam forming / angle measuring means for measuring an angle using the beam angle as a target angle. 2. The receiving beam forming and angle measuring means includes means for forming, by digital beam forming, three types of beams, a pencil beam, an amplitude comparison angle measuring beam, and a phase monopulse beam, in angle measurement on an elevation plane. The radar target angle measuring device according to claim 1, wherein: Wherein the received beam forming and angle measuring means, Oite angle measuring elevation plane unnecessary from said relationship between the receiving beam directional angle and fluctuations in the output value and the estimated elevation angle in the amplitude comparison angle measuring beam 3. The radar target angle measuring device according to claim 2, further comprising means for evaluating an influence of a signal. Wherein said reception beam forming and angle measuring means, Oite angle measuring elevation plane, the reshaping of the receive beams for minimizing the influence of the unnecessary signal, using the measured angle values obtained during processing 3. A radar target angle measuring apparatus according to claim 2, further comprising a means for selecting from a beam for amplitude comparison angle measurement. 5. The reception beam forming / measuring means forms a plurality of reception beams having different angles from each other in an elevation plane and an azimuth plane, and re-forms a reception beam in which the influence of an unnecessary signal is minimized. An elevation plane angle measurement unit and an azimuth plane angle measurement unit that measure the angle of the beam as a target angle, and further, the reception of the azimuth plane angle measurement unit based on the angle measurement value obtained by the elevation plane angle measurement unit. 2. The radar target angle measuring device according to claim 1, further comprising means for re-forming a beam. 6. The reception beam forming / measuring means forms a plurality of reception beams having different angles from each other in an elevation plane and an azimuth plane, and re-forms a reception beam in which the influence of an unnecessary signal is minimized. An elevation plane angle measurement unit and an azimuth plane angle measurement unit that measure the beam angle as a target angle, and further, the reception of the elevation plane angle measurement unit based on the angle measurement value obtained by the azimuth plane angle measurement unit. 2. The radar target angle measuring device according to claim 1, further comprising means for re-forming a beam.