JP2001264427A - Radar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radar which effectively measures the angular position of a target corresponding to an area of the angular measurement. SOLUTION: First and second digital beam forming circuits 74, 75 are connected in parallel to an active array radar receiver so that the mono-pulse angular measurement signal and the amplitude comparison angular measurement signal are obtained from an angular error voltage measurement circuit 73 and an amplitude comparison circuit 77, respectively by switching circuits 761, 762 in a selectively switching manner. As a result, in the angular measurement area having a low angle of elevation, the amplitude comparison angular measurement is correct with less influence of the multi-pass such as the ground reflecting wave. On the other hand, in the angular measurement area having the high angle of elevation, the mono-pulse angular measurement can be achieved with a large angle of elevation, and the target position (angular measurement) of the target can be effectively detected corresponding to a designated coverage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention divides a scanning space area, selectively performs either a monopulse angle measurement or an amplitude comparison angle measurement in accordance with the division, and accurately and effectively measures a target position. The present invention relates to a radar device that can be angled.

[0002]

2. Description of the Related Art It is known that the position and orientation of a target can be measured by monopulse angle measurement or amplitude comparison angle measurement using radar waves.

FIG. 3 shows a DBF (Digital Beam Form) configured to perform a conventional monopulse angle measurement.
FIG. 1 is a configuration diagram showing a (ing: digital beam forming) radar apparatus.

[0004] That is, a large number of antenna elements 1 such as dipole antennas are arranged so as to form a plane array, and a transmission / reception module 2 is connected to each antenna element 1. Each of these transmission / reception modules 2 is connected to a transmission system via a power supply unit 3 to a transmitter 4, a receiver 5, an A / D converter 6, a signal processing unit 7 and a radar indicator (not shown). A receiving system constituting the receiver is connected.

The transmission / reception module 5 has built-in transmission / reception amplifiers, phase shifters, transmission / reception path changeover switches, control circuits for these circuits, and the like. The transmission / reception switching and transmission / reception are controlled by a control signal from a radar control unit 8. The phase of the radar transmission signal is controlled, and the antenna element 1 is configured to form an antenna pattern in a specified direction.

[0006] The reflected signal from the target received by the antenna element 1 is amplified by the receiver 5, converted into a digital signal by the A / D converter 6, and digitally formed (DBF) by the signal processing unit 7. It is supplied to the circuit 71.

As shown in FIG. 4A, the DBF circuit 71 introduces, via the antenna element 1, target reflected signals from two antenna patterns 6a and 6b which partially overlap in the elevation angle direction, for example. Sum beam weight coefficient data 72a and difference beam weight coefficient data 72 of the antenna pattern set in the weight coefficient setting circuit 72.
4B, each signal of the sum beam 71a and the difference beam 71b is generated, and the angle error voltage calculation circuit 73 is generated together with the target reflected signal, as shown in FIG.
To supply.

The angle error voltage calculation circuit 73 calculates the sum beam 7
1a and the difference beam 71b, a voltage value on the angle error voltage characteristic curve as shown in FIG.
Since it is derived from 3a, the azimuth (elevation angle) of the target position can be detected by reading the voltage value.

For example, an elevation direction of a target position is detected (angle measurement).
As shown in FIG. 5, the antenna patterns of the sum beam 71a and the difference beam 71b formed by the digital beam forming circuit 71 are vertically and vertically (centered) with respect to the sum beam 71a directed to the target (M) direction. (The elevation angle), two difference beams 71b, 71b are formed.

That is, in the monopulse angle measurement, as shown in FIG. 5, the difference beam 71b directed downward (low elevation angle)
However, in addition to the direct wave from the target, the target reflected signal (indirect wave) reflected and received on the ground surface E is subjected to reception processing as noise, so that there is a disadvantage that an incorrect angle measurement is performed.

In the conventional radar apparatus shown in FIG. 3, the DBF circuit 71 forms two antenna patterns at slightly different angles in the elevation direction by setting the weight coefficient, and sets the reception amplitude level of the target reflected wave. It is also possible to perform so-called amplitude comparison angle measurement for detecting the target position azimuth from the difference.

This amplitude comparison angle measurement is different from the monopulse angle measurement shown in FIG. 5, and in angle measurement, two antenna patterns having a slight angle difference are formed toward the direction of the target position to measure the angle. Therefore, the spread of the beam in the angle measurement direction is small, and it is possible to avoid receiving the indirect wave on the multipath at a high level. However, since the amplitude comparison angle measurement is based solely on the relative comparison of the reception levels of two antenna patterns having different directivity directions, it is difficult to accurately detect the target position direction.

[0013]

In any case, the DB
In a conventional radar apparatus provided with an F circuit, a target position and azimuth is detected by one of a monopulse angle measurement and an amplitude comparison angle measurement in a DBF circuit.

However, in the monopulse angle measurement, as described above, as one of the multipaths, a position signal from a target area having a low elevation angle is easily detected as noise by ground reflected waves, and the target position azimuth is erroneously detected. There was a problem.

The amplitude comparison angle measurement detects the target position direction only from the difference in signal detection level between two partially overlapping antenna patterns, so that it is difficult to measure the angle with high accuracy.

Accordingly, it is an object of the present invention to provide a radar device capable of measuring a target position in a more accurate and optimum pattern in a simple configuration corresponding to a target position detection area (covered area).

[0017]

The radar apparatus according to the present invention comprises:
A first parallel-connected active array radar receiver
And second digital beam forming means, and the first and second digital beam forming means are provided with data of a sum beam weight coefficient and a difference beam weight coefficient, or data of an upper sum beam weight coefficient and a lower sum beam weight coefficient. Either a weight coefficient setting means configured to be able to supply correspondingly via a switching means, and a sum from the first digital beam forming means calculated and derived by receiving the data of the sum beam weight coefficient. A beam signal,
Angle error voltage calculation means for deriving a monopulse angle measurement signal based on the difference beam signal from the second digital beam forming means which has been calculated and received in response to the data supply of the difference beam weight coefficient; and An upper sum beam signal from the first digital beam forming means calculated and derived by receiving the data supply, and a second calculated and derived by receiving data supply of the lower sum beam weight coefficient.
And an amplitude comparison means for deriving an amplitude comparison angle measurement signal based on the lower sum beam signal from the digital beam forming means, and controlling the switching means to perform a switching operation corresponding to a predetermined angle measurement area. And control means for performing the control.

As described above, according to the present invention, the first and second DBF (digital beam forming) means are provided, and the switching coverage by the control means corresponding to a predetermined angle measurement area is set. Since either the monopulse angle measurement or the amplitude comparison angle measurement is selectively performed in response to the above, a radar device capable of performing an optimum angle measurement corresponding to the target position angle (coverage) can be realized.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a radar apparatus according to the present invention will be described below in detail with reference to FIGS. The same components as those of the conventional configuration shown in FIGS. 3 to 5 are denoted by the same reference numerals, and detailed description is omitted.

FIG. 1 is a block diagram showing an embodiment of a radar apparatus according to the present invention. In FIG.
A transmitting / receiving module 2 is connected to each of the multiple antenna elements 1 forming the surface array.
Is connected to a transmission system of the power supply unit 3 and the transmitter 4, and a receiver 5, an A / D converter 6, a signal processing unit 7, a radar indicator (not shown), and the like, which constitute a reception system.

The transmission / reception module 5 has built-in transmission / reception amplifiers, phase shifters, transmission / reception path switching switches, control circuits for these circuits, and the like. The transmission / reception switching and radar are performed by a signal from the radar control unit 8. The phase of the transmission signal is controlled, and the antenna element 1 forms a predetermined antenna pattern in the designated direction.

The reflected signal from the target received by the antenna element 1 is amplified by the receiver 5 and then passed through the A / D converter 6 to form first and second digital beamformers (parallel connected). DBF) circuits 74 and 75.

The first and second DBF circuits 74 and 75 are provided by a first switching circuit 761 with the sum beam weight coefficient data 72a stored in the weight coefficient setting circuit 72.
And the difference beam weight coefficient data 72b, or the upper sum beam weight coefficient data 72c and the lower sum beam weight coefficient data 72d are switched and supplied correspondingly. In this embodiment, the upper sum beam refers to an antenna pattern having a larger elevation angle with respect to the target position direction, and the lower sum beam partially overlaps the upper sum beam and is centered on the target position direction. Is referred to as an antenna pattern having a smaller elevation angle.

Therefore, the sum beam weight coefficient data 72
The first digital beam forming circuit 74 which has calculated and derived the sum beam signal upon receiving the supply of a, and the second digital beam forming circuit 75 which has calculated and derived the difference beam signal upon receiving the difference beam weight coefficient data 72b. , Each second
Is connected to the angle error calculation circuit 73 in the same manner as in the conventional configuration, and the monopulse angle measurement signal of the target position calculated here is derived from the output terminal 73a.

On the other hand, by the switching operation of the first switching circuit 761, the first digital beam forming circuit 74 receiving the supply of the upper sum beam weight coefficient data 72c calculates and derives the upper sum beam signal, and outputs the lower sum beam weight. The second digital beam forming circuit 7 receiving the supply of the coefficient data 72d
5 calculates and derives a lower sum beam signal, and a second switching circuit 7
The amplitude comparison circuit 77 is supplied to the amplitude comparison circuit 77 via 62, so that the amplitude comparison circuit 77 generates an amplitude measurement signal for the target position and azimuth and derives it from the output terminal 77a.

The first and second switching circuits 761, 76
2 is performed synchronously by a control signal from the switching control circuit 78. In this embodiment, the switching control circuit 7
8 is configured to synchronously switch control the first and second switching circuits 761 and 762 based on a command signal from the angle measurement area setting circuit 79.

That is, the angle measurement area setting circuit 79 preliminarily divides the angle measurement area (covered area) of the target position into two in the elevation direction, and performs monopulse angle measurement when detecting the target position azimuth in the high elevation angle area. In addition, when detecting the target position and azimuth in the low elevation angle region, the switching control circuit 7 performs an amplitude comparison angle measurement.
8 is supplied with a command signal. First by the switching control circuit 78
And by the switching operation of the second switching circuits 761 and 762,
The angle measurement signal of the coverage area corresponding to the command signal is derived from the output terminal 73a of the angle error calculation circuit 73 or the output terminal 77a of the amplitude comparison circuit 77.

Therefore, according to this embodiment, as shown in FIG. 2, the target angle measurement at a low elevation angle which is easily affected by the reflected wave (indirect wave) of the target reflected wave from the ground is narrow in the elevation angle direction. Within the angle range, the upper (higher elevation angle) sum beam 77
a and the lower (lower elevation angle) sum beam 77b, the amplitude comparison angle measurement is performed, so that it is not affected by multipath such as an indirect wave reflected on the ground surface E, and erroneous detection can be avoided to improve reliability. This is to perform highly accurate target position angle measurement.

On the other hand, the target position angle measurement in the relatively high elevation angle region is controlled by the switching operation of the switching control circuit 78 so that the first and second switching circuits 761 and 762 perform monopulse angle measurement.
Since the switching operation is performed, a highly accurate target angle measurement can be performed similarly to the conventional device shown in FIG.

As described above, according to the radar apparatus of the present invention incorporating the active array radar receiver, the monopulse angle measurement and the amplitude comparison angle measurement can be switched according to the elevation coverage of the target scan. , High-precision monopulse angle measurement,
The angle measurement function can be improved by effectively switching to amplitude comparison angle measurement in which erroneous detection due to indirect waves due to multipath is avoided.

[0031]

According to the present invention, a monopulse angle measurement and an amplitude comparison angle measurement are switched in accordance with the angle measurement area division of the target position, and a radar apparatus having an improved angle measurement function is provided. can do.

[Brief description of the drawings]

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

FIG. 2 is an antenna pattern diagram showing a state of amplitude comparison angle measurement in the device shown in FIG. 1;

FIG. 3 is a configuration diagram showing a conventional DBF radar device.

FIG. 4 is an explanatory diagram illustrating a procedure of monopulse angle measurement in the device shown in FIG. 3;

FIG. 5 is an antenna pattern diagram showing a state of monopulse angle measurement in the device shown in FIG. 3;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 antenna element 2 transmission / reception module 3 feed unit 4 transmitter 5 receiver 6 A / D converter 7 signal processing unit 72 weight coefficient setting circuit (weight coefficient setting means) 73 angle error calculation circuit (angle error calculation means) 74 first Digital beam forming circuit (DBF means) 75 second digital beam forming circuit (DBF means) 761 first switching circuit (switching means) 762 second switching circuit 77 amplitude comparison circuit 78 switching control circuit (switching control means) 79 Angle measurement area setting circuit 8 Radar controller

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J021 AA05 AA09 AA11 AB03 DB03 DB04 EA02 FA13 GA02 HA04 JA10 5J070 AC02 AC12 AD05 AD07 AD09 AD10 AK07 AK22

Claims (2)

[Claims] A first and a second digital beam forming means connected in parallel to an active array radar receiver; a sum beam weight coefficient and a difference beam weight coefficient provided to the first and second digital beam forming means; Weight data setting means configured to be able to supply either the data of the sum beam weight coefficient or the data of the upper sum beam weight coefficient via the switching means, and data supply of the sum beam weight coefficient. The sum beam signal from the first digital beam forming means calculated and received in response to the difference beam weight, and the difference beam signal from the second digital beam forming means calculated and derived in response to the data supply of the difference beam weight coefficient. An angle error voltage calculating means for deriving a monopulse angle measuring signal, and a data supply of the upper sum beam weight coefficient. The upper sum beam signal from the first digital beam forming means, which is calculated and derived by receiving the data, and the lower sum from the second digital beam forming means, which is calculated by receiving the data supply of the lower sum beam weight coefficient. An amplitude comparison unit that derives an amplitude comparison angle measurement signal from the sum beam signal, and a control unit that controls the switching unit to perform a switching operation corresponding to a predetermined angle measurement area. A radar device characterized by the following. 2. The switching means, based on a predetermined elevation angle, outputs data of a sum beam weight coefficient and a difference beam weight coefficient in a higher elevation angle region, and an upper sum beam weight coefficient and a difference beam weight coefficient in a lower elevation angle region. 2. The radar apparatus according to claim 1, wherein data of a lower sum beam weight coefficient is supplied to each of said first and second digital beam forming means.