JPH06201815A - Radar device - Google Patents

Abstract

PURPOSE:To obtain a radar device for forming beams by obtaining a waiting for maximizing signal S/N after forming the beams. CONSTITUTION:The radar device is provided with a memory 8 for temporarily retaining the video signal from each receiver 2 and a DFT discriminating equipment 6a for creating a discrimination by receiving the video signal which is temporarily retained at the memory 8 and then forming a plurality of reception beams with a low side lobe at an entire transmission covering range. Further, it is provided with a wait forming equipment 4a for constituting a matched filter in the target-detected direction by the DFT discriminating equipment, thus improving S/N ratio by a conventional signal processor 5 in time-axis direction, obtaining an approximate electric, wave arrival direction by the plurality of DFT discriminating equipment 6a on formation of beams, and then forming beams again by constituting the matched filter in angle direction for maximizing the S/N ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device using a digital beam forming (DBF) array antenna.

[0002]

2. Description of the Related Art FIG. 3 shows the structure of a conventional digital beam forming radar apparatus.
Is an array antenna for receiving radio waves, 2 is a receiver for converting a microwave reception signal from each element of the array antenna into a video signal, and 3 is a receiver output video signal and a beam pointing direction Beamformer for beamforming using beam pattern weight data, 4
Is a weighting former that combines beam pattern weight data and beam pointing weight to create a beam forming weight, and 5 is an S / N based on the formed beam signal.
It is a radar signal processor that performs improvement, S / C improvement, target detection, angle measurement / distance measurement, tracking data processing, and the like.

In this conventional DBF radar device, when forming a reception beam, the target detection processing is performed by scanning the reception beam in correspondence with the transmission direction.

[0004]

In the conventional DBF radar device, the misdetection of the target was avoided by forming the pattern of the low side lobe. However, in general, the low sidelobe pattern has a low antenna gain, which inevitably causes the received signal S / N to be somewhat low.

The present invention has been made to solve such a problem, and an object thereof is to configure a matched filter in a target direction to maximize the S / N of a received signal.

[0006]

In order to solve the above-mentioned problems, a weighting method is used in which a received video signal output from a receiver corresponds to each time (distance bin) and forms a matched filter with respect to its incident direction. Reception beam forming (DBF) is performed. A device to which a plurality of DFT discriformers are added as a device for detecting the incident direction, or a multi-monopulse calculator is further added to the output of the FFT multi-beam former.

[0007]

The radar apparatus according to the present invention has a plurality of DFTs.
By adding a multi-monopulse calculator to the discriminator or the FFT multi-beam former, the incident angle direction is analyzed and the phase gradient measured between the elements corresponding to the incident angle direction is obtained. For the gradient, the S / N of the video signal can be maximized by using the complex conjugate function for weighting and beam combining again by the beam former (DBF).

[0008]

【Example】

Example 1. FIG. 1 shows an embodiment of the present invention, in which 1 to 3 and 5 are exactly the same as the conventional device. Reference numeral 8 is a memory for temporarily holding the video signal from the receiver. 6a receives the temporarily stored video signal,
It is a DFT discriformer which forms a discreet by forming a plurality of low sidelobe reception beams over the entire transmission coverage area. Reference numeral 4a is a weight former which constitutes a matched filter in the direction in which the target is detected.

The operation of the radar device thus configured will be described in detail. The received video signal obtained by amplifying or frequency converting the microwave signal received by each array element is recorded in the memory. This received video signal is φm
(Θ). Where m is the array element number and θ
Is the incident direction of the radio wave. Using this received video signal,
In the DFT discriminator, a plurality of DFT circuits is used to make a discretization covering the entire search coverage area by the operation shown in Formula 1.

[0010]

[Equation 1]

From the discriminant value Dk of this calculation result, θ
Find k. If radio waves are incident on the planar array from the obtained θk direction, the received signal φm (θk) measured by each element is

[0012]

[Equation 2]

It is expressed as follows. For this incident signal, the original beamformer

[0014]

[Equation 3]

The matched filter is formed by executing the calculation of (1) to obtain the beam-formed signal Ψ (θk). This beam forming signal Ψ (θk) is a direction θ close to the true target direction.
The beam is formed into k and the gain is high, and since it is a matched filter, the forming loss is small. In other words, the antenna gain is high and the S / N value can be maximized.

Example 2. FIG. 2 shows another embodiment of the present invention, in which 1 to 3 and 5 are exactly the same as the conventional device. Reference numeral 8 is a memory for temporarily recording the video signal from the receiver. Reference numeral 6b is an FFT multi-beam former which receives the temporarily recorded video signal and forms reception beams for the number of elements over the entire transmission coverage area. Reference numeral 7 denotes a multi-monopulse calculator which creates a plurality of discretities by using the multi-beams corresponding to the formed elements and calculates a target detection direction. Reference numeral 4b is a weight former that creates weights for forming a matched filter in the direction in which the target is detected.

The operation of the thus constructed radar apparatus will be described in detail. Similar to the first embodiment described above, the received video signal obtained by amplifying or frequency converting the microwave signal received by each array element by each receiver is recorded in the memory. The received video signal is φm (θ). here,
m is the element number. θ is the incident direction. This video signal is output by the FFT multi-beam former having one channel of FFT circuit that covers the entire search coverage area.

[0018]

[Equation 4]

The calculation is performed to form a multi-beam Φk. From this multi-beam Φk

[0020]

[Equation 5]

The discrete value Fk is obtained by performing the monopulse calculation as described above. The incident angle θk is obtained from this Fk value. The subsequent processing is the same as in the first embodiment.

[0022]

The present invention has the following effects by being configured as described above.

S / N by conventional signal processing in the time axis direction
In addition to improvement, multiple DFT discriminators or FFT multi-beam formers are used to determine the approximate arrival direction of the radio wave and a matched filter is formed in the angular direction to re-form the beam to maximize S / N. can do. In applications such as radar, improvement in distance performance, distance measurement, angle measurement, and tracking accuracy can be expected.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a conventional radar device.

[Explanation of symbols]

 1 array antenna 2 receiver 3 beam former 4a weighting former 4b weighting former 5 signal processor 6a DFT discriformer 6b FFT multi-beam former 7 multi-monopulse calculator 8 memory

Claims (2)

[Claims] 1. An array antenna for transmitting and receiving radio waves, a receiver group for converting a microwave signal received from each element of the array antenna into a video signal, and an output video signal of the receiver group is temporarily stored. D that forms a monopulse discretion from the memory and the output video signal of the receiver group
An FT (Discrete Fourier Transform) discriminator and a weighting generator for calculating a weighting for forming a matched filter in the angular direction from the direction of target detection by the DFT (Discrete Fourier Transform) discriminator And a beam former for synthesizing the output video signals of each receiver group temporarily stored in the previous memory using this weighting, and a signal processor for processing the formed beam output in the time axis direction. A radar device characterized by the above. 2. An array antenna for transmitting and receiving radio waves, a receiver group for converting a microwave signal received from each element of the array antenna into a video signal, and an output video signal of the receiver group is temporarily stored. A memory, an FFT multi-beam former which forms beams by the number of input video channels by FFT (Fast Fourier Transform) from the output video signals of the receiver group, and a plurality of disks which generate sum and difference patterns by this multi-beam A multi-monopulse calculator that creates a clock, a weighting calculator that calculates a weighting for forming a matched filter in the angular direction from the direction of the target detected by this multi-monopulse calculator, and this weighting A beam former for synthesizing output video signals of respective receivers temporarily held in a memory; A radar apparatus comprising a signal processor for processing the processed beam output in the time axis direction.