JP2699740B2 - 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 search radar system,
In particular, the present invention relates to a radar device that obtains target azimuth information by performing monopulse angle measurement processing on the azimuth.

[0002]

2. Description of the Related Art Conventionally, this type of radar apparatus has a target of 3
In order to obtain dimensional position information, the pencil beam has been scanned in azimuth and elevation directions according to a predetermined beam scanning program. For example, in the case of a search radar apparatus, a method of sequentially forming a plurality of adjacent pencil beams at each elevation angle in the same direction and rotating the pencil beams in a horizontal plane is used to search a wide area. In the case of a tracking radar, the target is continuously irradiated with a pencil beam in order to obtain precise three-dimensional position information of the target.

FIG. 2 shows a configuration example of a conventional radar apparatus.
In this radar apparatus, first, in order to perform beam scanning in a required direction, a beam direction controller 1 generates a beam direction control signal and outputs the signal to the antenna 2. Antenna 2
Forms a pencil beam in a designated direction according to a beam direction control signal as shown in FIG . this
When the beam adjacent in the azimuth direction is
Name. In order to perform the azimuth measurement by the monopulse method, the antenna 2 simultaneously forms two types of beam patterns, that is, a sum pattern and a difference pattern as shown in FIG. Antenna 2
Is converted from a high frequency to an intermediate frequency in the receiver 3 and then output to the signal processor 4. The signal processor 4 performs a suppression process on a received signal other than the target signal, determines a signal having a certain level or higher from the received signal as a reflected signal from the target signal, and outputs the signal to the amplitude comparator 5 and the storage device 7. . As shown in FIG. 5B, the storage unit 7 stores a target signal in an azimuth adjacent beam scanned earlier than the current azimuth.
(Sum video of target signal received by beam one direction ahead)
Is output to the amplitude comparator 5. The amplitude comparator 5 compares the sum video of the target signal of the current azimuth and the target signal of the azimuth adjacent beam scanned in the past, and when the latter is larger,
The signal is output to the monopulse angle calculator 6. The monopulse angle measurement calculator 6 calculates the azimuth of the target signal by monopulse angle measurement processing and outputs it.

Here, the principle of the monopulse angle measurement processing is shown in FIG.
This will be described with reference to FIG. A sum video and a difference video are obtained as a target signal 104 from two types of antenna patterns, a sum pattern 101 and a difference pattern 102. Assuming that the amplitude values of the sum video and the difference video are Σ and Δ, respectively, the deviation angle θ of the sum pattern from the beam nose can be obtained from the amplitude characteristic curve of FIG. By adding the deviation angle θ and the beam direction, a target azimuth can be obtained.

[0005]

In this conventional radar apparatus, since the monopulse angle measurement is performed as the azimuth angle measurement, a dead zone where the angle measurement accuracy is deteriorated occurs near the beam nose of the sum pattern. Here, the dead zone will be described with reference to FIG. In the sum pattern 101, since the reception level is high near the beam nose, the target signal 105
Is easy to receive. However, since this area corresponds to the vicinity of the null point of the difference pattern 102, the difference video of the target signal 105 is buried in noise, and an accurate amplitude value Δ cannot be obtained. For this reason, as shown in FIG. 4, there is a problem that this area becomes a dead zone 201 where an accurate angle measurement value cannot be obtained. Further, as the distance from the beam nose of the sum pattern 101 increases, the S / N ratio of the sum video deteriorates, which causes a problem that the angle measurement accuracy deteriorates. An object of the present invention is to provide a radar device with improved angle measurement accuracy.

[0006]

The radar apparatus according to the present invention comprises:
Compare and interpolate the sum video amplitude of two beams adjacent in the azimuth direction to a radar device that has a beam direction controller, antenna, receiver, signal processor, monopulse goniometer, memory, and amplitude comparator. An amplitude comparison goniometer that calculates the target azimuth by calculating, and an azimuth of the output of the monopulse goniometer, are used as inputs, and the vicinity of the nose of the sum pattern and
And the amplitude comparison measurement near the middle of the two adjacent beams.
The output of the angle calculator is weighted, and the two
In the middle area, the output of the monopulse angle measurement calculator is weighted.
A weighting coefficient generator for generating a weighting coefficient as multiplied, the generated weighted by the weighting coefficient generator
A weighted average value calculator for performing a weighted average calculation of the azimuth angle of the output of the monopulse angle measurement unit and the azimuth angle of the output of the amplitude comparison angle measurement unit based on the coefficient .

[0007]

As shown in FIG . 5 (c), the output of the amplitude comparison and angle measurement calculator is weighted in the vicinity of the beam nose of the sum pattern and in the vicinity of the middle of two adjacent beams. A weighting coefficient is set so as to weight the output of the angle measurement arithmetic unit, and the weighted average calculation is performed by a weighted average value calculator together with the output of the monopulse angle measurement arithmetic unit and the output of the amplitude comparison angle measurement arithmetic unit. Output as the target azimuth.

[0008]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention.
The same parts as those of the prior art shown in FIG. 2 are denoted by the same reference numerals, and are denoted by a beam controller 1, an antenna 2, a receiver 3, a signal processor 4, an amplitude comparator 5, a monopulse angle measuring device. The operations of the arithmetic unit 6 and the storage unit 7 are the same as those in the related art, and thus the description is omitted. In the present invention, an amplitude comparison angle measurement calculator 8, a weighting coefficient generator 9, and a weighted average value calculator are further provided in this configuration. The amplitude comparison and angle calculation unit 8 calculates the sum video amplitude value of the target signal of the current azimuth output from the signal processor 4 and the sum video amplitude value of the target signal of the beam adjacent in the azimuth direction of the storage unit 7 output. Is calculated and interpolated to calculate the azimuth angle of the target, which is output. The weighting coefficient generator 9 generates a weighting coefficient by using the target azimuth output from the monopulse angle measurement calculator 6 as an input parameter.

The method of determining the weighting coefficient is as follows.
First, the azimuth angle of the output of the amplitude comparison angle measurement calculator 8 is determined by the target fraction ( depending on the shape of the target and the properties in radio wave propagation).
Instead of a large error due to temporal amplitude fluctuations , there is no dead zone as in monopulse angle measurement, and it can be seen that the accuracy is uniform with respect to azimuth. Conversely, the azimuth angle of the output of the monopulse angle measuring unit 6 has no error due to the target fractionation, but has a dead zone and S / S in a region apart from the beam nose of the sum pattern.
Angle measurement accuracy is deteriorated due to deterioration of N.

Therefore, as the weighting coefficient, the output of the amplitude comparison and angle measurement calculator 8 is weighted near the beam nose of the sum pattern and near the middle of two adjacent beams.
In the middle of the two areas, a weighting coefficient is set so that the output of the monopulse angle measuring unit 6 is weighted conversely. The weighting coefficient determined in this way is input to the weighted average value calculator 10 together with the output of the monopulse angle measurement arithmetic unit 6 and the output of the amplitude comparison angle measurement arithmetic unit 8, and after performing the weighted average calculation, the target azimuth is calculated. Output as corners.

[0011]

As described above, according to the present invention, in the azimuth angle measurement, the monopulse angle measurement process is performed, and the amplitude comparison angle measurement process is performed using the sum video of the two beams adjacent to the direction. The weighted average calculation takes into account the error in the dead band in the monopulse angle measurement, the error due to S / N deterioration in the area apart from the beam nose of the sum pattern, and the error in the target fractionation in the amplitude comparison angle measurement. This has the effect of improving angular accuracy.

[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 block diagram illustrating an example of a conventional radar apparatus.

FIG. 3 is a conceptual diagram of a beam pattern in a monopulse angle measurement method.

FIG. 4 is an amplitude characteristic curve in a monopulse angle measurement method.

FIG. 5 is a diagram for explaining azimuth adjacent beams in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Beam direction controller 2 Antenna 3 Receiver 4 Signal processor 5 Amplitude comparator 6 Monopulse angle measuring unit 7 Storage unit 8 Amplitude comparison angle measuring unit 9 Weighting coefficient generator 10 Weighted average value calculator

Claims (1)

(57) [Claims] 1. A and the beam direction controller for controlling the beam direction in accordance with a predetermined beam scanning program, said beam direction
An antenna capable of simultaneously forming a sum pattern and a difference pattern for monopulse angle measurement in the azimuth direction in the beam direction determined by the direction controller, and a receiver for receiving a signal through the antenna , a signal processor for suppressing the received signal other than the target signal, the monopulse angle measuring calculator for calculating the azimuth angle of the target by the amplitude characteristic of the sum pattern and difference pattern, the target signal of the signal processing output from the signal processor And an amplitude comparator for comparing the amplitude of the sum video of two beams adjacent in the azimuth direction, and comparing and interpolating the amplitude of the sum video of two beams adjacent in the azimuth direction to calculate the target. An amplitude comparison angle measurement calculator for calculating an azimuth angle,
The azimuth of the output of the monopulse angle measurement unit is input and the sum
Near the nose of the pattern and between the two adjacent beams
In the vicinity, weighting is applied to the output of the amplitude comparison angle measurement calculator,
In the middle area between the two areas, the monopulse measurement is performed.
A weighting coefficient generator for generating a weighting coefficient that multiplies the weight to output angular calculator, the weighting coefficient generating
Characterized in that on the basis of the generated weighting coefficients vessel and a weighted average calculator to perform a weighted average calculation of the azimuth angle of said amplitude comparison angle measuring operation output and the azimuth angle of the monopulse angle measuring operation output Radar equipment.