JP3139865B2 - 3D 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 three-dimensional radar apparatus for performing a height measurement operation.

[0002]

2. Description of the Related Art As a conventional three-dimensional radar device, a device which mechanically scans an antenna to detect a target signal direction, and a device which performs angle measurement by a monopulse system are typical. This monopulse method forms two types of patterns (sometimes three types in terms of azimuth and elevation) called a sum pattern and a difference pattern of antenna beams, and performs azimuth detection from the power ratio.

[0003] Such a three-dimensional radar apparatus has a great technical problem of detecting a target azimuth (elevation angle, azimuth angle) with high accuracy by suppressing a height measurement error due to multipath in an angle measurement operation. As specific methods for realizing this problem, recently proposed SR (Super Resolution), ME
M (Maximum Entropy Method), MLM (Maximum Like
lihood Method) has been widely studied.

However, all of the azimuth detection methods using these algorithms are intended for a system in which the antenna is constituted by a one-dimensional array in a vertical direction, and perform azimuth detection calculation based on output signals of each antenna element. However, it cannot be applied to a radar apparatus that uses an output signal after beam combining as in the monopulse system.

Also, the azimuth calculation based on the signal of each antenna element is effective only when there is a signal, and is completely unnecessary when there is no signal. Furthermore, the technology for determining the presence or absence of a target from the above method has not yet been determined,
It was incompatible with the conventional target detection technology.

In particular, since these azimuth detection systems are originally aimed at detecting the direction of a disturbing signal, the performance with respect to a target signal buried in an unnecessary signal is not always satisfactory.

[0007] Regarding the above-mentioned angle measurement algorithm such as SR and MLM, reference is made to “Spectral Analysis and Reference”.
Adaptive Array Superresolution Techniques ”(Proc
eedings of the IEEE, vol. 68, No. 6, Jun. 1980),
“Angular Spectra in Rader Applications”, “Aper
ture Sampling Techniques for Precision Direction F
inding ”(IEEE Trans on Airospace and Eelectronic
Systems, Vol. AES-15, No. 6, Nov. 1979), the details of which are not directly related to the present invention.
Here, the description is omitted.

[0008]

As described above, in the conventional three-dimensional radar apparatus, an effective technique for improving the accuracy of detecting the azimuth of the target has not been established. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a three-dimensional radar device that can improve the accuracy of target direction detection.

[0009]

In order to achieve the above object, a three-dimensional radar apparatus according to the present invention comprises a one-dimensional array in which at least a plurality of antenna elements are arranged in a vertical direction, and the one-dimensional array is used to increase the elevation angle. An antenna system for forming a reception beam of the one-dimensional array, target detection means for detecting a target signal component from a reception signal obtained by each antenna element of the one-dimensional array to calculate a target distance, and an antenna system for each antenna element of the one-dimensional array. An analog / digital conversion circuit for converting the obtained reception signal into data, a storage circuit for storing reception data of each antenna element obtained by this circuit for at least a time corresponding to a repetition period of a transmission signal, and a detection circuit detected by the target detection means. Data reading control means for reading out received data corresponding to the target distance from the storage circuit, and receiving data read out by this means. Signal processing means for suppressing an unnecessary signal by performing coherent signal processing, the angle measuring operation on the received data obtained in this way subjected to other respectively,
Angle measuring means for calculating a target elevation angle.

[0010]

In the three-dimensional radar device having the above-described structure, a series of target detection processes are performed on the received output of the one-dimensional array to detect the position of the target, and the distance information thereof is extracted.
After converting the received signal of each antenna element obtained in the one-dimensional array into data, it is stored in the storage circuit in advance for at least one PRI period, and the data read control circuit uses the target distance information obtained by the target detection processing, The reception data corresponding to the distance is extracted. Then, the received data is subjected to coherent signal processing by a signal processing circuit to suppress unnecessary signal components, and then sent to an angle measurement arithmetic circuit to perform angle measurement. In this case, since only the received data at the time of detecting the target is input to the angle measurement arithmetic circuit, useless calculation is eliminated even when a high-precision angle measurement algorithm is applied. Can be found.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIG.

FIG. 1 shows a configuration of a three-dimensional radar apparatus according to the present invention. In FIG. 1, the antenna system 11 includes a one-dimensional array 111 in which a plurality of antenna elements a are arranged in a vertical direction, and a reflector 112 for collecting radio waves in the one-dimensional array 111. The receiving beam is scanned in the azimuth direction (AZ direction) by forming a reception beam and rotating and driving the reflector 112 in the horizontal direction.

The received signal of each antenna element a output from the one-dimensional array 111 is converted into a digital signal by the A / D conversion circuit 12 and then supplied to the beam forming circuit 13. The beam forming circuit 13 forms a beam pattern in the EL direction by phase control or the like for each antenna element, and synthesizes and outputs the beam pattern.

The received signal output from the beam forming circuit 13 is sent to a signal processing circuit 14. This signal processing circuit 14 performs coherent signal processing such as MTI, pulse compression, and Doppler processing on the received signal to suppress unnecessary signal components. The output signal of the signal processing circuit 14 is sent to the target detection circuit 15. The target detection circuit 15 detects a target position by performing processing such as detection, CFAR, and threshold determination on an input signal, and calculates a distance to the target.

On the other hand, the digital reception signal of each antenna element a output from the A / D conversion circuit 12 is sent to the storage circuit 16 as it is. This storage circuit 16 stores a received signal for at least one PRI (transmission pulse repetition cycle) time for each antenna element. On the other hand, the target detection circuit 1
The target distance information obtained in step 5 is stored in the data read control circuit 17.
Sent to

The data read control circuit 17 reads out received data of each antenna element at a corresponding distance from the storage circuit 16 based on the target distance information from the target detection circuit 15. The read reception data is stored in the signal processing circuit 1
At 8, the same coherent signal processing as in the target detection system is performed to suppress unnecessary signal components. Each received data output from the signal processing circuit 18 is sent to the angle measurement operation circuit 19.

This angle measuring circuit 19 is provided with the aforementioned SR,
A target elevation angle is calculated by applying an angle measurement algorithm such as MEM or MLM. In this angle measurement operation, the azimuth can be obtained. However, in order to reduce the circuit scale, the azimuth is obtained from the rotation angle of the antenna system 11 here.

That is, in the three-dimensional radar apparatus having the above-described configuration, the beam forming circuit 13, the signal processing circuit 14, and the target detecting circuit 15 perform beam synthesis and perform a series of target detecting processes to detect a target position. Extract the distance information. Conventional technology can be applied to this target detection system.

On the other hand, after the reception signal of each antenna element a obtained by the one-dimensional array 111 is converted into data by the A / D conversion circuit 12, it is stored in the storage circuit 16 in advance for at least one PRI period, and the data read control circuit 17 In, using target distance information obtained by the target detection system, reception data corresponding to the distance is extracted. Then, after performing a coherent signal processing on each received data in the signal processing circuit 18 to suppress unnecessary signal components, the signal is sent to the angle measurement arithmetic circuit 19,
Perform angle measurement operation.

In this case, since only the received data at the time of detecting the target is input to the angle measurement arithmetic circuit 19, useless calculation is eliminated even if the above-described angle measurement algorithm is applied. An elevation angle can be obtained efficiently.

That is, since the received data input to the angle measurement operation circuit 19 is subjected to coherent signal processing, unnecessary signal components are suppressed and only weak target signal components are included. The high-precision arithmetic capability inherent in the algorithm can be maximally applied only to the target signal.

Therefore, in the three-dimensional radar apparatus having the above configuration, the received data at the time of detecting the target is extracted by using the target distance information obtained by the target detecting system. Will be available,
As a result, the accuracy of the target azimuth detection can be improved.

FIG. 2 shows another embodiment according to the present invention. The received signal of each antenna element output from the A / D conversion circuit 12 is subjected to coherent signal processing by the signal processing circuit 14 and is unnecessary. After suppressing the signal components, the beam is formed by the beam forming circuit 13 to form an elevation beam, and the combined output is input to the target detection circuit 15 to detect a target position and calculate a target distance.

In this case, the received data after the coherent signal processing is stored in the storage circuit 16, and thereafter the same processing as in FIG. 1 is performed. According to this configuration, coherent processing after reading becomes unnecessary, and the circuit scale can be further reduced.

The present invention is not limited to the above-described embodiment. For example, a part (sub-array) of a two-dimensional array can be used for the one-dimensional array 111 used for the antenna system 11. In this case, the reflector 112 is not always necessary.

The operation after the data read control circuit 17 can be performed by software operation using a computer or the like. In this case, the software calculation can be provided with a function of a target detection system, and further provided with a function of synthesizing a difference pattern, so that application to a monopulse system is also possible. In addition, various modifications may be made without departing from the spirit of the present invention, and the present invention can be similarly implemented.

[0027]

As described above, according to the present invention, it is possible to provide a three-dimensional radar apparatus capable of improving the accuracy of detecting the direction of a target.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration of another embodiment according to the present invention.

[Explanation of symbols]

11: antenna system, 111: one-dimensional array, 112: reflector, 12: A / D conversion circuit, 13: beam forming circuit, 14: signal processing circuit, 15: target detection circuit, 16 ...
Storage circuit, 17: data read control circuit, 18: signal processing circuit, 19: angle measurement operation circuit.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01S 7/02 G01S 13/42-13/44

Claims (3)

(57) [Claims] 1. A one-dimensional array in which at least a plurality of antenna elements are arranged in a vertical direction, an antenna system for forming a reception beam in an elevation direction by the one-dimensional array, and an antenna system obtained by each antenna element in the one-dimensional array. Target detection means for detecting a target signal component from a received signal to calculate a target distance; an analog / digital conversion circuit for converting a received signal obtained by each antenna element of the one-dimensional array into data; A storage circuit for storing reception data of the antenna element for at least a time corresponding to a repetition period of the transmission signal; a data read control unit for reading reception data corresponding to a target distance detected by the target detection unit from the storage circuit; Signal that performs coherent signal processing on each of the received data read by the means to suppress unnecessary signals And management means performs goniometric calculation for the received data obtained in this way, three-dimensional radar apparatus and a measuring angle calculating means for calculating a target elevation angle. 2. A beam forming circuit for forming a reception beam by synthesizing a reception signal obtained by each antenna element of the one-dimensional array, and performing a coherent signal processing on an output of the circuit. The three-dimensional radar device according to claim 1, further comprising: a signal processing circuit that suppresses an unnecessary signal component; and a target detection circuit that detects a target signal component from an output of the circuit and calculates a target distance. 3. A signal processing circuit for performing coherent signal processing on received signals obtained by each antenna element of the one-dimensional array to suppress unnecessary signal components, and an antenna processed by the circuit. A beam forming circuit for forming an elevation beam by synthesizing a received signal of each element, and a target detecting circuit for detecting a target signal component from an output of the circuit and calculating a target distance. 3. The three-dimensional radar device according to 1.