JPH04147079A - Method and apparatus for processing radar signal - Google Patents

Abstract

PURPOSE:To calculate velocity of a target which is moving in a parallel direction of a radar by calculating difference in shifts between respective time points and a rate of time change by digital reception signals with respect to two optional elements on an array antenna. CONSTITUTION:A signal received by an antenna element 1 is converted into a digital signal through a receiver 2 and an A/D-converter 3 provided on each element 1, and then it is subjected to beam formation in a digital beam formation unit 4. After the beam is detected in a detection unit 5, the result and information obtained during processing are output to a target information processing unit. At the same time distance information included in the information is output to an azimuth direction and velocity calculation unit 8. Reception signals of two optional elements 1 in input signals to the beam formation unit 4 are input to a phase calculation unit 6, a phase of each signal at each time point is calculated, a difference in phase between the signals of the two elements 1 is calculated in a phase difference calculation unit 7, and a calculation unit 8 obtains velocity of a target moving in a parallel direction to a radar with rapid response time based on the phase difference and its rate of time change.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention uses an array antenna and a DBF (Digi
Search and tracking radars that perform beam forming using tal Beam Forming technology, such as aircraft-mounted D
This is related to BF radar.

[Conventional technology]

FIG. 2 is a configuration diagram of a search and tracking radar that uses a conventional phased array antenna and performs microwave beam synthesis. In the figure, (1) is an antenna element of an array antenna that emits or receives radio waves, (9) is a phase shifter that sets the phase of each antenna element, and α1 is a phase shifter that adds the received signals from each antenna element. a microwave beam combiner that performs beam formation; (5) performs multi-target detection based on the beam formation result of the microwave beam combiner;
In conventional search and tracking radars, which are the detection unit that outputs detection results to the target information processing unit in the subsequent stage, when the Doppler velocity of the target is used for target detection processing, it is difficult to detect targets moving in a direction parallel to the radar. It could not be detected and was not intended for such a target. Furthermore, when target detection processing uses amplitude information, that is, power, rather than the Doppler velocity of the target, the specifications of the target moving in a direction parallel to the radar are determined by computer calculations in the target information processing section.

[Problems to be Solved by the Invention] Conventional search and tracking radars need to be able to deal with targets in all forms of movement in preparation for the diversification of threats.

This invention was made to solve these problems, and utilizes the characteristics of DBF to determine the phase difference between the received signals between two antenna elements, and further calculates the rate of change over time to create a signal parallel to the radar. The purpose of this is to calculate the speed of a target moving in a certain direction.

[Means to solve the problem]

The radar signal processing method and device according to the present invention include:
By the time rate of change of the target distance information and the phase difference of the received signal between any two elements of the antenna.

This system is provided with means for calculating the speed of a target moving in a direction parallel to the radar.

[Effect]

In this invention, we take advantage of the characteristics of DBF.

By calculating the phase difference of the received signal between any two elements of the antenna and its rate of change over time in the signal processing section, the speed of the target moving in the direction parallel to the radar can be obtained with a fast response time.

〔Example〕

FIG. 1 shows an overall configuration diagram of an embodiment according to the present invention. In this figure, (1) is the antenna element of the array antenna, (2) is the receiver provided for each antenna element, and (2) is the receiver provided for each antenna element.
3) is an A/D converter that converts the analog reception signal output from the receiver (2) into a digital signal, and (4) is an A/D converter that inputs the output of the A/D converter (3) and performs digital beam formation. (5) is the digital beam forming unit that performs the detection of multiple targets, (5) is the detection unit that performs the detection of multiple targets as well as the output, and (6) is the A/D converter (
a phase calculation unit that calculates the phase at each time of the digital reception signal for arbitrary two elements among the outputs of (7);
) is a phase difference calculation unit that calculates the phase difference between the two elements at each time based on the output of the phase calculation unit (6) for the two antenna elements, and (8) is the output of the target output from the detection unit (5). Distance information and the phase difference calculation unit (calculates the speed of the target moving in the direction parallel to the radar based on the output result of the sword,
This is an azimuth direction velocity calculation unit that outputs the result to a subsequent target information processing unit.

Next, the operation of this device will be explained.

Figure 3 shows that for a target moving in a direction parallel to the radar,
It is a diagram showing the principle of the present invention for detecting the speed. FIG. 3(a) and FIG. 3(b) are each time t = t
FIG. 3 is a diagram showing how radio waves arrive from the target to the antenna aperture at l and t = t2.

In the figure, (9) and α[ indicate the arrival direction of the target and radio waves at time 1=11. Similarly, αυ and α
2 indicates the arrival direction of the target and radio waves at time t=t2. At time 1=11, radio waves from a target located at distance R9 and azimuth θ1 are received by each antenna element, but at this time, the position of the signal received by any two elements 2, for example the 1st and mth elements The phase difference Δψ,1 is expressed by the following equation.

dlm #o1 flll Δψt1=2"λ Δψt+ ' dl, : Phase difference between two elements (1st and mth) of the received signal at time 1=1. Spacing between the 1st and mth antenna elements θ1: Time t= Arrival direction λ of the radio wave from the target at t1: wavelength of the radio wave Similarly to the time t=t2, the phase difference Δψ,2 of the received signal between the two antenna elements of the first and mth antennas is expressed by the following equation.

Δψt2' Phase difference between two elements (1st and mth) of the received signal at time t=t2 d: Distance between the 1st and mth antenna elements θ2: Direction of arrival of radio waves from the target at time t=t2 λ: wavelength of radio wave On the other hand, the distance R6 that the target travels between time 1=11 and t=t2 is expressed by the following equation.

Rs=R (sin θ2-earth θ1)
(3) Therefore, the speed V8 of the target moving in the direction parallel to the radar is.

Using formula ill~(3), it is expressed as the following formula v8:
Speed of the target λ moving in a direction parallel to the radar: Wavelength R of the radio wave: Distance of the target Δψ, Δψ° 'Ht2 at times t=t1 and t=t2.

Phase difference dlm of received signals between two elements: spacing between the 1st and mth antenna elements In the device according to the present invention, the signal received by the antenna element f1+ is transferred to the receiver (2) provided in each element and the A/
After passing through the D converter (3) and being converted into a digital signal, the signal is input to the digital beam forming section (4).

Beam formed. The beam-formed result is sent to the detector (
5), and after being subjected to detection processing, the results and information obtained in the processing process are output to the subsequent target information processing section. At the same time, among the target information obtained by the detection unit (5), the distance information R is
) is output. I cut it. Digital beam forming section (4)
The received signals of any two elements 9, for example, the 1st and m-th elements among the digital received signals of N elements inputted to the phase calculator (6), calculate the phase of each received signal at each time. Calculated. The phase difference calculation unit (7) inputs the results calculated by each phase calculation unit (6) and calculates the received signal between the two elements at each time described as Δψ, Δψ, 2 in Equation 9 (4). Calculate the phase difference.

The azimuth velocity calculation unit (8) receives the target distance information R from the detection unit (5), and receives the received signal between the two antenna elements at times t = tl and t = tl2 from the phase difference calculation unit (7), respectively. The speed vs of the target traveling in the direction parallel to the radar is calculated according to equation 1 (4) and output to the subsequent target information processing section. In equation (4), it is assumed that the wavelength λ of the radio wave and the element spacing d1m are known.

〔Effect of the invention〕

As explained above, this invention utilizes the characteristics of DBF to calculate the phase difference between two arbitrary elements of an array antenna at each time based on the digital received signal.
Further, by calculating the rate of change over time, the speed of the target moving in the direction parallel to the radar can be calculated with a quick response time in the signal processing section.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a radar signal processing device according to the present invention, FIG. 2 is an overall configuration diagram of a conventional radar signal processing device,
FIGS. 3(a) and 3(b) are diagrams explaining the invention in detail. In the figure, (1) is an antenna element, and (2) is a receiver. (3) is an A/D converter, and (4) is a digital beam forming unit. (5) is the detection section, (6) is the phase calculation section, (Force is the phase difference calculation section. (8) is the azimuthal velocity calculation section. In each figure, the same reference numerals indicate the same or equivalent parts. .

Claims (2)

[Claims] (1) In a search and tracking radar that uses an array antenna and performs digital beam formation, any two of the outputs of the A/D converter provided for each antenna element.
The phase difference between the two elements is determined using the digital reception signal for the element, and the speed of the target moving in the direction parallel to the radar is calculated from the time change rate of the phase difference and the target distance information, and the target information processing in the subsequent stage is performed. Radar signal processing method for output to the section. (2) an array antenna that receives radio waves from a target; a receiver for each antenna element of the array antenna;
an A/D converter that converts analog reception signals output from each of the receivers into digital signals; and a digital beam forming section that receives the output of the A/D converter as input and performs digital beam formation. , a detection unit that detects a target from the output result of the digital beam forming unit, and a phase calculation unit that calculates the phase at each time of the digital reception signal for arbitrary two elements among the outputs of the A/D converter. , a phase difference calculation unit that calculates a phase difference at each time between the two antenna elements based on calculation results of each phase calculation unit for the two elements, and target distance information obtained in the detection unit and the phase difference calculation unit. Radar signal processing characterized by comprising: an azimuth direction speed calculation section that calculates the speed of a target moving in a direction parallel to the radar based on the calculation result of and outputs the calculation result to a subsequent target information processing section. Device.