JP2001272464A - Radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radar device which enables a high-precision observation of high precision to easily be made. SOLUTION: Beam forming circuits 61 to 6n perform multi-beam formation including disturbance suppression processing. A target detecting circuit 8 detects a target. A decision circuit 9 determines an angle measurement system from target detection information. An angle measurement processing circuit 10 performs angle measurement operation by selecting a necessary beam output from the multi-beam according to the angle measurement system determined by the decision circuit 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a radar device for observing a target such as a flying object using an array antenna.

[0002]

2. Description of the Related Art For example, a radar apparatus for obtaining information such as a position and a distance related to a target such as a flying object often includes an array antenna in which a plurality of antenna elements are arranged. As an angle measuring method in such a radar device,
A phase monopulse angle measurement method, an amplitude comparison angle measurement method, and the like are known.

In this type of radar apparatus, in general, the same beam is formed in target detection processing and angle measurement processing, so that processing such as using an optimum angle measurement method according to the target detection position is performed. Can not. For this reason, there has been a problem that the angle measurement accuracy is greatly affected by environmental factors such as multipath and the observation accuracy may be greatly reduced.

On the other hand, in recent years D
In a BF (Digital Beam Forming) radar device, a reception beam can be re-formed by storing a digitally converted antenna element signal.
By making it possible to select the most suitable angle measurement method according to the target detection position, the above-mentioned problem can be solved.

[0005] However, in this type of radar apparatus, SLC (Side Lob) is required as the reception beam is re-formed.
e Canceller) had to be performed again. For this reason, an enormous signal processing process is required before shifting from the detection processing to the angle measurement processing, and the burden on resources increases. This is a cause that causes various adverse effects such as a delay in the processing time, and leads to a deterioration in radar performance.

[0006]

As described above, the conventional radar apparatus has a problem that the observation accuracy is reduced depending on the target detection position. In order to avoid such a problem, it is necessary to repeat signal processing with a large load, which causes a problem that a load on resources is large.

[0007] The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a radar device capable of easily performing high-precision observation.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an antenna unit in which a plurality of antenna elements are arranged in an array, and a radar echo signal arriving at the antenna unit is provided for each of the antenna elements. Receiving and digitally converting, receiving means for transmitting a plurality of digital element signals, and forming a plurality of mutually different receiving beams from the plurality of digital element signals obtained by the receiving means,
Multi-beam forming means for generating a reception signal for each beam; storage means for storing outputs of a plurality of reception beams obtained by the multi-beam formation means; and a plurality of reception beams formed by the multi-beam formation means From the output of the target information acquisition means for temporarily obtaining information on the position of the target, the space is divided into a plurality of regions with respect to the installation position of the own device, and the angle measurement method for the target is associated with these regions. Holding the correspondence and referring to the correspondence from the provisional target position information obtained by the target information obtaining means to determine an angle measurement method to be applied when calculating an angle measurement value for the target; Means for selectively acquiring a required beam output from a plurality of beam outputs stored in the storage means based on the angle measurement method determined by the determination means. In, and so that and a measuring angle processing means for calculating the angle measurement value for the target.

[0009] Alternatively, in the present invention, further, a transmitting means for generating a radar transmission signal, a radar transmission signal generated by the transmitting means is led out to the antenna section and radiated from the antenna section toward space, A circulator for guiding the radar echo signal arriving at the antenna unit to the receiving means.

According to the above arrangement, the received signal based on the echo reflected from the target is converted into a digital signal, and a plurality of received beams are simultaneously formed by the multi-beam forming means based on the digital element signal.

Based on these reception beams, position information such as altitude information of the target is temporarily calculated by the target information obtaining means. On the other hand, the correspondence between the space area and the angle measurement method is held in the determination unit in advance, and the method of performing the angle measurement processing on the target by comparing the position information with the correspondence is used. It is determined by the determining means. Based on the angle measurement method determined here, angle measurement processing is performed on the target by the angle measurement processing means.

Generally, depending on the situation such as elevation angle and distance,
There is an angle measurement method that can obtain the most accurate value. For example, the monopulse angle measurement method can obtain relatively high-precision data, but in a low-elevation angle region, accuracy is reduced due to the influence of multipath. Therefore, in the low elevation angle region, if an amplitude comparison angle measurement method having high resistance to multipath is used, a more accurate angle measurement value can be obtained. Such a determination is made in the determination unit.

The output of the received beam used as data when performing the calculation for the angle measurement process is stored in the storage means in the form of digital data. Then, based on the determined angle measurement method, the angle measurement processing is performed again based on the stored reception beam, so that highly accurate angle measurement data can be quickly obtained.

Further, according to the present invention, when beam forming is performed by the multi-beam forming means, unnecessary wave suppression processing is also performed. As a result, the unnecessary wave component removal processing has already been completed when the provisional information is calculated by the target information acquisition means. In the present invention, the received beam output is stored, the stored data is read out, and the angle measurement is performed based on the stored data. Therefore, the complicated processing related to the beam forming and the unnecessary wave suppression processing is executed again. No need to do. Accordingly, it is possible to quickly shift to the angle measurement processing, and it is possible to greatly reduce the load on resources including software processing and the like.

Further, in the present invention, the multi-beam forming means includes a receiving beam for obtaining provisional target position information in the target information obtaining means, and a calculation of the angle measurement value in the angle measurement processing means. And the receiving beam of the same.

By doing so, the number of beams required for target observation can be reduced. For example, it is possible to avoid an increase in the circuit scale of the multi-beam forming means, and thus to reduce the size and weight of the apparatus. Alternatively, it can contribute to cost reduction.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a radar apparatus according to the present invention. The radar device shown in the figure has a transmission circuit 1 and a circulator 2
An array antenna unit 3 having m antenna elements # 1 to #m, receiving circuits 41 to 4m, analog / digital (A / D) conversion circuits 51 to 5m, and beam forming circuits 61 to 6n. It includes beam storage circuits 71 to 7n, a target detection circuit 8, a determination circuit 9, and an angle measurement processing circuit 10.

The transmission circuit 1 generates a transmission RF (Radio Frequency) signal at a predetermined transmission repetition cycle, and outputs the transmission RF signal to the array antenna unit 3 via the circulator 2. Further, the transmission circuit 1 outputs a transmission timing signal indicating the transmission timing of the transmission RF signal to the beam forming circuits 61 to 6n and the target detection circuit 8 described later.

The array antenna section 3 is an array antenna in which a plurality of antenna elements are arranged, and radiates a transmission RF signal input via the circulator 2 to a space. Then, the reflected echoes of the transmission RF signal are received by the respective antenna elements from the space, and output to the receiving circuits 41 to 4m via the circulator 2 respectively.

The receiving circuits 41 to 4m amplify and detect signals from the antenna elements # 1 to #m provided via the circulator 2 with low noise and extract received signals to obtain received data.

The received data transmitted from the receiving circuits 41 to 4m are respectively supplied to A / D conversion circuits 51 to 5m and converted into digital signals, and are formed into beam forming circuits 61 to 6n.
Output to That is, the individual beam forming circuits 61 to 6n
Are supplied with digital reception signals of m systems corresponding to all the antenna elements # 1 to #m.

The beam forming circuits 61 to 6n perform a beam forming operation using the given m digital reception signals. The beam forming circuits 61 to 6n also perform unnecessary wave suppression processing such as SLC processing and clutter removal processing at the time of beam formation. The n beam outputs obtained here are sent to beam storage circuits 71 to 7n, respectively.

The beam storage circuits 71 to 7n store the given beam outputs as data and transmit the beam outputs to the target detection circuit 8 and the angle measurement processing circuit 10.

The target detection circuit 8 performs a target detection process based on the beam outputs given from the beam storage circuits 71 to 7n based on the transmission timing signal from the transmission circuit 1.
Get preliminary summary information about your goals. Information such as the target detection distance and the target detection beam number obtained here is given to the determination circuit 9.

The determination circuit 9 determines an angle measurement method capable of obtaining the most accurate angle measurement data for the target based on the information provided from the target detection circuit 8, and determines the determined angle measurement method. The angle measurement processing circuit 10 is notified of the method. Examples of the angle measurement method include a monopulse angle measurement method and an amplitude comparison angle measurement method, and the parameters related thereto include an off-bore angle, a squint angle, and the like. Judgment circuit 9
Produces a beam that meets these conditions with the n
The beam is selected from the plurality of beams, and is supplied to the angle measurement processing circuit 10 as a beam to be subjected to angle measurement.

The angle measurement processing circuit 10 selects a necessary beam output from the beam outputs output from the beam storage circuits 71 to 7n based on the angle measurement method notified from the determination circuit 9, and executes angle measurement processing. Execute.

FIG. 2 shows the configuration of the angle measurement processing circuit 10.
The angle measurement processing circuit 10 includes switches 101 and 102 for selecting a beam required for angle measurement. Switch 101
The switch 102 selects a required beam output from the beam outputs according to the angle measurement method instructed by the determination circuit 10. The beams selected by the switches 101 and 102 are output to the angle measurement operation circuit 103, and the angle measurement operation is performed. The angle measurement operation circuit 103 outputs an angle measurement value. In the above configuration, the number of antenna elements is m and the number of formed beams is n.

Next, the operation of the radar apparatus having the above configuration will be described. FIG. 3 is a diagram showing transmission and reception timings and a concept of multi-beam forming which is a feature of the present invention.

As shown in FIG. 3, the transmission RF signal formed by the transmission circuit 1 is transmitted at the timing of the transmission pulse synchronized with the transmission repetition period. The shape of the transmission beam is preferably set to an elevation angle cosecant beam or the like that preferably covers a wide area. In the subsequent reception period, a multi-beam in which a plurality of pencil beams are superimposed is formed by the beam forming circuits 61 to 6n, and a desired elevation angle coverage area is covered. Unwanted wave suppression processing such as SLC processing and clutter removal processing is performed at this time.

FIG. 4 is a diagram showing an example of a multi-beam provided for processing in the target detection circuit 8 and the angle measurement processing circuit 10. Based on the digital element signals output from the A / D conversion circuits 51 to 5m, respective beam forming circuits 61 to 6
At n, a plurality of reception beams having different directional angles are formed.
The formed beam is used for target detection processing in the target detection circuit 8 (that is, processing for obtaining provisional target information) and angle measurement processing in the angle measurement processing circuit 10.
Not all beams need to be used in both circuits. That is, there may be a beam used only for target detection, a beam used only for angle measurement, and a beam used for target detection and angle measurement.

At this time, if the beam arrangement is determined so that as many beams as possible can be used for both the target detection process and the angle measurement process, the number of beams to be formed can be reduced, and the beam formation related to the beam formation can be reduced. This can contribute to a reduction in the circuit scale.

FIG. 4 shows the detection beam and the angle measurement beam separately. In a region where high-precision angle measurement cannot be performed with the detection beam, the angle measurement beam is arranged at a position that complements the interval between the detection beams. By arranging the beams densely, highly accurate angle measurement can be performed. However, since the scale of the beam forming circuits 61 to 6n increases, it is necessary to determine an optimal beam arrangement. When the angle measurement processing circuit 10 performs monopulse angle measurement, a Δ beam is also formed for angle measurement.

FIG. 5 is a diagram showing an example of a procedure for selecting an angle measurement method. FIG. 5 shows that an angle measurement method and an angle measurement parameter are selected from information such as a detection distance and a detection beam number. Here, one of a monopulse angle measurement method using a detection beam and its difference beam, an amplitude comparison angle measurement method using a detection beam, and an off-bore amplitude comparison angle measurement method using no detection beam is selected.

That is, in the high elevation angle region, the most accurate monopulse angle measurement method is selected from the above three methods. In the low-elevation-angle region, since the angle measurement data with high accuracy cannot be obtained by the monopulse angle measurement method due to the influence of multipath, the amplitude comparison angle measurement method having high resistance to multipath is selected. Furthermore, in the low elevation area, the influence of multipath becomes large, so the multipath resistance is higher.
The off-bore amplitude comparison angle measurement method in which the target is removed from the boresight of the beam is selected.

With reference to FIG. 6, an example of the division of the angle measuring system will be described. The graphic shown by the solid line in FIG. 6 shows a desired elevation angle coverage area with respect to the radar installation point. According to FIG. 6, the elevation angle coverage is divided into five regions by a boundary indicated by a dotted line in the elevation angle direction based on the detection beam number and a boundary indicated by a dotted line according to the detection distance, and an optimum angle measurement method for each region is determined. It is shown to be present.

In general, it is convenient to use the phase monopulse angle measurement method in the high elevation angle region. In a low elevation angle area, particularly in an area where a multipath is strong, it is preferable to use the off-bore amplitude comparison angle measurement method.

The determination circuit 10 determines whether the target is as shown in FIG.
In (5), which area is present is determined from the detection beam number and the detection distance, and an angle measurement method suitable for each area is determined. The determination circuit 10 outputs an instruction signal to the switches 101 and 102 in order to select a beam necessary for executing the determined angle measurement method from the multi-beams (see FIG. 2). Switch 101 and switch 1
Reference numeral 02 selectively outputs the beam output to the angle measurement arithmetic circuit 103 in accordance with the given instruction signal.

The switches 101 and 102 output the selected beam outputs to the angle measurement arithmetic circuit 103, and the angle measurement arithmetic circuit performs angle measurement based on the angle measurement method from the determination circuit 10.

As described above, in this embodiment, a multi-beam is formed based on the received signal, and the individual beams subjected to the unnecessary wave suppression processing are stored. It also calculates general information such as the position related to the target from the multi-beam, determines the angle measurement method that can obtain the most accurate angle measurement data from this, selects the beam output required for this angle measurement method, and performs measurement. Angle calculation is performed.

With this configuration, it is possible to select an optimal angle measurement method according to the observation environment such as the presence or absence of multipath and the position of the target, and it is possible to improve the accuracy of observation. Further, the data to be used for the angle measurement processing is stored in a state where unnecessary wave components such as an interference signal have already been suppressed, and the data is read out and the angle measurement processing is performed, so that the processing can be speeded up. In addition, there is no need to execute unnecessary wave component suppression processing at the time of angle measurement processing, so there is no need to execute complicated software processing.
The burden on resources can be greatly reduced.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the monopulse angle measurement, the amplitude comparison angle measurement, and the off-bore amplitude comparison angle measurement 3
Although the various angle measurement methods have been described, the above description of the operation is merely an example, and the angle measurement method is not limited to the above three methods. Also, the shape of each receiving beam that forms a multi-beam is not limited to a pencil beam,
Any shape may be set.

The radar apparatus according to the present invention forms a multi-beam based on a received signal, determines an angle measurement method according to target detection information, selects a required beam output, and performs an angle measurement operation. That is the basic idea. For this reason, the radar device according to the present invention can be used as a receiving device in a bistatic radar device. FIG. 7 shows the configuration of a radar device that performs this type of operation.
Shown in

As shown in FIG. 7, the bistatic radar device is a radar device in which a transmitting device TR and a receiving device RR are separately configured in a system, and the receiving device RR is a radar signal radiated from the transmitting device TR. And the target is analyzed. In this case, there is no transmission pulse from the reception device RR, and only a reception multi-beam is formed.

In the above configuration, the receiving device RR according to the present invention. In this case, the transmitting circuit 1 and the circulator 2 are omitted from the configuration of FIG. 1, and the received RF signals from the array antenna unit 3 are directly used as the receiving circuits 41 to 4.
m. Further, the transmission timing signal provided from the transmission circuit 1 to the beam forming circuits 61 to 6n and the target detection circuit 8 in FIG. 1 is replaced with a synchronization signal from the transmission device TR.

In this embodiment, the processing for one transmission pulse has been described. However, the above-described processing is repeated for each transmission repetition cycle, and the tracking of a moving target can be quickly and accurately performed. It is possible to do with.

In addition, various modifications can be made without departing from the gist of the present invention.

[0047]

As described in detail above, according to the present invention, a multi-beam is formed based on a received signal, and each beam output after unnecessary wave suppression processing is stored. In addition, rough information such as a position related to a target is calculated from the multi-beams, and an angle measurement method capable of acquiring the most accurate angle measurement data is determined. Then, a beam output required for the angle measurement method is selectively fetched from a storage unit to perform angle measurement calculation processing.

With this configuration, it is possible to provide a radar device capable of easily performing high-precision observation. Also, since the beam subjected to the unnecessary wave suppression processing is stored and the angle measurement processing is performed based on the stored beam, the processing can be speeded up and the load on resources can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a circuit block diagram showing a configuration of the angle measurement processing circuit 10 of FIG.

FIG. 3 is a diagram conceptually showing a shape of a beam formed at the time of transmission and reception in the radar apparatus according to the present invention.

FIG. 4 is a diagram showing an example of a multi-beam provided for processing in a target detection circuit 8 and an angle measurement processing circuit 10;

FIG. 5 is a diagram illustrating an example of a processing procedure for selecting an angle measurement method.

FIG. 6 is a view for explaining an example of a criterion for performing separation of an angle measurement method.

FIG. 7 is a diagram illustrating a configuration example of a bistatic radar device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Transmission circuit 2 ... Circulator 3 ... Array antenna part 41-4m ... Receiving circuit 51-5m ... Analog / Digital (A / D) conversion circuit 61-6n ... Beam forming circuit 71-7n ... Beam storage circuit 8 ... Target detection Circuit 9 ... Judgment circuit 10 ... Angle measuring circuit 101, 102 ... Switch 103 ... Angle measuring arithmetic circuit

Claims (6)

[Claims] An antenna unit in which a plurality of antenna elements are arranged in an array, and a radar echo signal arriving at the antenna unit is received and converted to digital for each antenna element, and a plurality of digital element signals are transmitted. Receiving means; forming a plurality of receiving beams different from each other from the plurality of digital element signals obtained by the receiving means to generate a receiving signal for each beam; Storage means for respectively storing the outputs of the plurality of received beams, and target information obtaining means for temporarily obtaining information on the target position from the outputs of the plurality of received beams formed by the multi-beam forming means; Is divided into a plurality of areas with respect to the installation position of the own device, and the angle Holding the response relationship, with reference to the correspondence relation from the provisional target position information obtained by the target information acquiring unit,
Determining means for determining an angle measurement method to be applied when calculating an angle measurement value for the target; and a plurality of beam outputs stored in the storage means based on the angle measurement method determined by the determination means. A radar apparatus for selectively taking in a required beam output from a target and calculating an angle measurement value for the target. A transmitting means for generating a radar transmission signal; a radar transmission signal generated by the transmitting means being derived to the antenna section and radiated from the antenna section toward a space; 2. The radar apparatus according to claim 1, further comprising a circulator that derives an incoming radar echo signal to the receiving unit. 3. The method according to claim 1, wherein the determining unit divides the space into a plurality of regions based on an elevation angle and a distance, and performs any one of a monopulse angle measurement method and an amplitude comparison angle measurement method on these regions. 3. The radar apparatus according to claim 1, wherein the angle measuring method is used. 4. The radar apparatus according to claim 1, wherein said multi-beam forming means includes unnecessary wave suppressing means for suppressing unnecessary wave components when forming a plurality of reception beams. 5. A receiving beam for obtaining provisional target position information in said target information obtaining means, and a receiving beam for calculating said angle measuring value in said angle measurement processing means. 3. The radar device according to claim 1, wherein the radar device is also used for both. 6. The target information obtaining means includes at least the target position information including identification information of a reception beam used to obtain the information, and distance information to a target to which the information is applied. The radar device according to claim 1 or 2, wherein: