JPH09184881A - Three dimensional radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable angle measuring at sufficient target reception level in the angle measurement of a target angle with a three dimensional radar device. SOLUTION: By providing an angle measuring data reliability judgment means 6, a desired reception level is monitored. When it does not reach a predetermined reference value of reception level, a signal indicating that the reliability of the measured angle processing data is not satisfactory is sent to a beam scan scheduling means 10. Then the beam scan schedule is changed so as to trace again the angle measurement for the same target. A beam scan azimuth/ angle calculation means 9 having received the changed schedule signal calculates to reduce the angle switch step width of the beam angle for the angle measurement, sends the beam angle control signal to an aerial device and raise the desired reception level by reducing the step width.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic scanning system 3
The present invention relates to a technique for improving the angle measurement accuracy of a target elevation angle (elevation angle) in a three-dimensional radar device.

[0002]

2. Description of the Related Art A conventional electronic scanning type three-dimensional radar device has already been searched and captured in the middle of a target search scan of an aerial beam based on a beam scanning schedule which determines time allocations of aerial beam search and tracking scans. The elevation angle of the target is measured, and the tracking process of the target is performed based on the obtained angle data. An example of the beam scanning schedule is shown in FIG.

That is, one or a plurality of targets (A, B, C, D) that have already been captured are tracked for a short time while one round of search and scan is performed in the air space defined by the three-dimensional radar device. Scan. At this time, the elevation angle of the target to be tracked is measured (angle measurement). The angle measurement is performed by slightly changing the angle of the antenna beam with respect to the tracking target, transmitting and receiving at at least two angles, and calculating from the respective target reception levels at that time. This is because the antenna pattern is known, that is, the angle from the central axis and the amount of attenuation at that angle are known, and the elevation angle of the beam central axis when transmitting and receiving is naturally known. The principle is that if the target reception level at the beam angle is measured, it is possible to know which angle is between the elevation angles when transmitting and receiving. This relationship is illustrated in FIG.

Three curves in the figure (two solid lines, one dotted line)
Is a curve showing the antenna pattern. The horizontal axis represents the elevation angle and the vertical axis represents the target reception level. The curve shows the antenna pattern, which is ₂ when the angle of the maximum direction of the reception level, that is, the beam direction is φ ₁ and φ 2.
Two curves are drawn with solid lines. That is, the antenna beam height angle switching step width is Δφ. Since they have the same antenna pattern, the curved shape is naturally the same.

If the reception level when the antenna beam is φ ₁ is A and the reception level when φ ₂ is B is B, the target elevation angle is φ _a . On the contrary, if the reception level when the antenna beam is φ ₁ is B and the reception level is φ ₂ is A, the target elevation angle is φ _b .

Similarly, the antenna beam angle is φ ₁
Reception level is in C, and elevation angle of the target as long as D when phi ₂ becomes phi _c when. In this way, track tracking processing is performed while measuring the target elevation angle.

[0007]

However, the above conventional angle measurement has the following problems. Now, if the noise level of the receiver is N, the reception level D is the noise level N
It will be lower. Therefore, the target received signal when the target of the elevation angle φ _c is received by the antenna beam φ ₂ is buried in the receiver noise and cannot be detected, or even if it is detected, the level is unstable because it is superimposed on the noise. Is. Therefore, in such a case, there is a problem that the angle measurement becomes impossible or is very unstable and unreliable.

An object of the present invention is to provide a three-dimensional radar device equipped with an angle measuring means capable of coping with such a case in view of the above problems of the prior art.

[0009]

The present invention has the following means in order to achieve the above object. That is, the three-dimensional radar device of the present invention measures the elevation angle of a target that has already been searched and captured in the middle of a target search scan of an aerial beam based on a beam scanning schedule that determines the time allocation of the search scan and the tracking scan of the aerial beam. An electronic scanning three-dimensional radar device that performs angle processing and performs target tracking processing based on the obtained angle data, wherein the target reception level when performing angle measurement processing reaches a predetermined level. If not, the angle measurement processing data reliability determination means that outputs a signal indicating that the angle measurement processing data is not reliable, and when the signal is received, the target is tracked again at the next tracking time of the beam scanning schedule. Beam scanning scheduling means for instructing the beam scanning and the elevation step for angle measurement when the re-tracking instruction is received from the beam scanning scheduling means. Is a three-dimensional radar apparatus characterized by having a beam scanning elevation calculation means to be smaller than the case of tracking.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention transmits and receives waves at a certain antenna beam angle with respect to a target as described above, then transmits and receives again with a change in angle, and from the respective target reception levels, the above 2
In the angle measuring means for calculating the target angle between the two angles, when the reception level from the target is low and the accuracy of the angle measurement cannot be sufficiently obtained, the interval between the two angles is narrowed, that is, the step width of the angle change. The means for increasing the reception level by increasing the precision by reducing the is applied to the elevation angle measuring means of the three-dimensional radar device.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment of the present invention. The antenna device 1 is an antenna of the electronic scanning type, and has a modularized receiving means 2 and transmitting means 3 mounted therein. The signal processing device 4 includes a target detection / angle measurement processing means 5 and an angle measurement processing data reliability determination means 6.
And track tracking processing means 7.

The beam controller 8 includes a beam scanning azimuth / elevation angle calculating means 9 and a beam scanning scheduling means 1.
Consists of zero. The schedule of the search scan and the tracking scan of the antenna beam is determined by the beam scan scheduling means 10, and the beam scan azimuth / elevation angle calculation means 9 receives the scheduling signal from the beam scan scheduling means 10, and based on this, the search scan. And calculation for beam direction control in tracking (angle measurement) scanning,
Based on this result, the phase shift control of the phased array for electronic scanning in the antenna device 1 is performed to control the antenna beam direction.

The search scan performs a constant beam scan according to a predetermined search pattern, but the tracking (angle measurement) scan requires that the aerial beam be directed toward a target already captured, and therefore its direction and The information on the elevation angle (elevation angle) is received from the target detection / angle measurement processing means 5. The transmission signal output from the transmitting means 3 is radiated from the antenna device 1 in the direction calculated by the beam scanning azimuth / elevation angle calculating means in this way, and the radio wave reflected and returned from the target in that direction is also the antenna device 1. Then, it is input to the receiving means 2. The output signal of the reception means 2 is sent to the target detection / angle measurement processing means 5. Here, if a target exists in the direction of the antenna beam, target detection is performed and angle measurement processing is performed on that target.

The principle of angle measurement is as described in the prior art. At this time, the angle measurement processing data reliability determination means 6 monitors the target reception level, and the reception level is a predetermined reference level. For example, when the level of the receiver noise level, or the level twice or three times that level is reached, the track tracking processing means 7 uses the angle data obtained by the target detection / angle measurement processing means 5. Based on the track tracking processing. The beam scanning scheduling means 10 also outputs a fixed schedule signal as shown in FIG.

On the other hand, for example, t _{1 in} FIG.
When the target reception level at the time of the angle measurement with respect to the target A has not reached the reference level, the angle measurement processing data reliability determination means 6 performs beam scanning scheduling on the signal indicating that the angle measurement processing data is not reliable. While sending to the means 10, the track tracking processing by the track tracking processing means 7 is temporarily stopped.

The beam scanning scheduling means 10, which has received the signal indicating the unreliability, changes the beam scanning schedule from (a) to (b) of FIG. That is, the schedule signal for outputting the angle measurement for the target A again is output at t _{2 when the} tracking angle measurement for the target B should be performed. Upon receiving this signal, the beam scanning azimuth / elevation angle calculation means 9 performs phase shift control calculation so that the beam direction at t ₂ again faces the target A, and the change step in the elevation angle (elevation angle) measurement is small. To be By doing so, the reception level from the target A rises, and accurate angle measurement can be performed.

This will be described again with reference to FIG. now,
For a target whose elevation angle is φ _c , when trying to measure angles with beam angles of φ ₁ and φ ₂ that have a width of Δφ in the step of switching the elevation angle, the reception level for φ ₂ is D and the noise level is Since it is lower than N, the angle measurement accuracy is not reliable. Therefore, if the switching step width is reduced to Δφ _S and the angle of one beam is changed from φ ₂ to φ ₃ , the target reception level in the φ _c direction becomes E, which exceeds the noise level N and is sufficient for angle measurement. Since it is a level
Angles φ ₁ and φ ₃ enable accurate angle measurement.

[0018]

As described above, in the three-dimensional radar device of the present invention, the angle measurement processing data reliability determining means monitors the target reception level during angle measurement, and the reception level is a predetermined reference value. If it does not reach, the track tracking processing based on the angle data is not performed, but a signal indicating that the angle measurement processing data is not reliable is sent to the beam scanning scheduling means, and the angle measurement is performed again for the same target. In addition, the beam scanning azimuth / elevation angle calculation means that receives the schedule signal reduces the elevation step (elevation angle) switching step width, so the target reception level becomes high, and accurate angle measurement and track tracking are achieved. Has the advantage that

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an electronic scanning type three-dimensional radar device of the present invention.

FIG. 2 is a beam scanning schedule diagram in the three-dimensional radar device.

FIG. 3 is an explanatory diagram of the principle of angle measurement and that the angle switching step width is reduced to increase the reception level and the angle measurement accuracy.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna device 2 Reception means 3 Transmission means 4 Signal processing device 5 Target detection / angle measurement processing means 6 Angle measurement processing data reliability determination means 7 Track tracking processing means 8 Beam control device 9 Beam scanning azimuth / elevation angle calculation means 10 Beam scanning Scheduling means

Claims (1)

[Claims] 1. A method for measuring the elevation angle of a target, which has already been searched and captured, during a target search scan of an aerial beam on the basis of a beam scanning schedule that defines time allocation for a search scan of an aerial beam and a tracking scan. An electronic scanning type three-dimensional radar device that performs target tracking processing based on the obtained angle data, and when the target reception level when the angle measurement process is performed does not reach a predetermined level, the angle measurement process is performed. Angle measurement processing data reliability determination means for outputting a signal indicating that the data is not reliable, and a beam for instructing to perform tracking of the target again at the next tracking time of the beam scanning schedule when the signal is received. When the re-tracking instruction is received from the scanning scheduling means and the beam scanning scheduling means, the elevation step for angle measurement is smaller than in the case of normal tracking. A three-dimensional radar device having a beam scanning elevation angle calculating means for combing.