JP2751616B2 - Radar signal processing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention uses an array antenna and uses a DBF (Digital Be
The present invention relates to a search and tracking radar for performing beam forming by an am forming technique, for example, an onboard DBF radar.

[Conventional technology]

FIG. 2 is a configuration diagram of a search and tracking radar for performing microwave beam synthesis using a conventional phased array antenna. 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, (1
0) is a microwave beam combiner that performs beam formation by adding the received signals from the antenna elements, and (5) performs target detection based on the beam formation result of the microwave beam combiner, and sends it to a target information processing unit at a subsequent stage. It is a detection unit that calculates a detection result.

In the conventional search and tracking radar, when a target Doppler speed is used for target detection processing, a target moving in a direction parallel to the radar cannot be detected, and such a target is not targeted. Further, when amplitude information, that is, power is used instead of the target Doppler velocity in the target detection processing, the specifications of the target moving in the direction parallel to the radar are obtained by computer calculation in the target information processing unit.

[Problems to be solved by the invention]

In conventional search and tracking radar, in preparation for diversification of threats,
You need to be able to address the goals of any form of exercise.

The present invention has been made to solve such a problem, and takes advantage of the characteristics of the DBF to determine the phase difference of the received signal between the two antenna elements, and further calculates the time change rate thereof so as to be parallel to the radar. The purpose is to calculate the speed of a target that moves in various directions.

[Means for solving the problem]

A radar signal processing method and apparatus according to the present invention calculate a velocity of a target moving in a direction parallel to the radar based on distance information of the target and a time change rate of a phase difference of a received signal between any two elements of the antenna. Means for performing the operation.

[Action]

In the present invention, the signal processing unit calculates the phase difference of the received signal between any two elements of the antenna and the time change rate thereof by utilizing the characteristic of the DBF, thereby achieving a quick response time and a movement in a direction parallel to the radar. The target speed is obtained.

〔Example〕

FIG. 1 shows an overall configuration diagram of an embodiment according to the present invention. In this figure, (1) is an antenna element of an array antenna, (2) is a receiver provided for each antenna element,
(3) is an A / D converter for converting an analog reception signal output from the receiver (2) into a digital signal, and (4) is a digital beam forming apparatus which receives an output of the A / D converter (3) as an input. (5) is a detection unit for detecting a target from the output of the digital beam formation unit (4), and (6) is an arbitrary two of the outputs of the A / D converter (3). A phase calculator for calculating a phase at each time with respect to a digital reception signal for the element; and (7) a phase difference for calculating a phase difference between the two elements at each time from the output of the phase calculator for the two antenna elements. Calculator,
(8) calculates the speed of the target moving in the direction parallel to the radar from the target distance information output from the detection unit (5) and the output result of the phase difference calculation unit (7), and outputs the result to the subsequent stage. Azimuth direction speed calculation unit that outputs to the target information processing unit.

 Next, the operation of this device will be described.

FIG. 3 is a diagram showing the principle of the present invention for detecting the speed of a target moving in a direction parallel to the radar. FIGS. 3 (a) and 3 (b) show the time t =
It is a diagram showing a state of arrival of the radio wave from the target at t ₁ and t = t ₂ to the antenna aperture. In the figure, (9) and (10) indicates the direction of arrival of the target radio wave at time t = t _1. Similarly, showing the (11) and (12) of the arrival direction of the target radio wave at time t = t _2. At time t = t ₁ , a radio wave from a target existing at a distance R and an azimuth angle θ ₁ is received by each antenna element. At this time, any two elements, for example, the first and m-th elements receive the radio wave. Signal phase difference Δ
_t1 is represented by the following equation.

Delta _t1: between two elements of the received signal at the time t = t _{1 (1}
Phase difference d _lm : 1st and mth antenna element interval θ ₁ : Arrival direction of radio wave from target at time t = t ₁ λ: Wavelength of radio wave Similarly, at time t = t ₂ phase difference delta _t2 of the received signal between the first and m-th antenna 2 elements is expressed by the following equation.

Delta _t2: between two elements of the received signal at the time t = t ₂ (1
Phase difference d _lm : 1st and mth antenna element interval θ ₂ : Arrival direction of radio wave from target at time t = t ₂ λ: Wavelength of radio wave On the other hand, time t = t ₁ to t = target between t ₂ proceeds distance R _S
Is represented by the following equation.

R _S = R (sin θ ₂ −sin θ ₁ ) (3) Accordingly, the target velocity V _S traveling in the direction parallel to the radar
Is represented by the following equation using equations (1) to (3).

V _S: speed of the target to move in a direction parallel to the radar lambda: wavelength of the radio wave R: target distance Δ _t1, Δ _t2: the phase difference of the received signal between two devices at a time t = t ₁ and t = t ₂ d _lm : 1st and mth antenna element spacing In the device according to the present invention, the signal received by the antenna element (1) is transmitted to the receiver (2) and A / D
After being converted to a digital signal through the converter (3),
The data is input to the digital beam forming unit (4) and is formed. The beam-formed result is input to the detection unit (5), and after being subjected to detection processing, the result and information obtained in the process are output to the target information processing unit at the subsequent stage. At the same time, the distance information R of the target information obtained by the detection section (5) is output to the azimuth direction velocity calculation section (8). Further, out of the digital reception signals for N elements input to the digital beam forming unit (4), the reception signals of arbitrary two elements, for example, the first and m-th elements are input to the phase calculation unit (6). The phase of each received signal at the time is calculated. In the phase difference calculation unit (7), each of the inputs the results calculated by the phase calculation unit (6), the received signal between two elements at each time described in equation (4) delta _t1, the delta _t2 Is calculated. The azimuth direction velocity calculation unit (8) receives the target distance information R from the detection unit (5) and the time difference t from the phase difference calculation unit (7).
= Get the phase difference of the received signals between the antenna 2 elements in t ₁ and t = t _2, and calculates the velocity V _S of the target traveling in equation (4) in a direction parallel to the slave connexion radar, subsequent target information Output to the processing unit. In equation (4), it is assumed that the wavelength λ of the radio wave and the element interval _dlm are known.

〔The invention's effect〕

As described above, the present invention takes advantage of the characteristics of the DBF to determine the phase difference between two elements at each time from a digital reception signal for any two elements of the array antenna.
Further, by calculating the time rate of change, the speed of the target moving in the direction parallel to the radar can be calculated with a fast response time in the signal processing unit.

[Brief description of the 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. 3A and 3B are diagrams for explaining the principle of the present invention. In the figure, (1) is an antenna element, (2) is a receiver,
(3) is an A / D converter, (4) is a digital beam forming unit, (5) is a detecting unit, (6) is a phase calculating unit, (7) is a phase difference calculating unit, and (8) is an azimuth direction. It is a speed calculation unit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

(57) [Claims] In a search and tracking radar for performing digital beam forming using an array antenna, a digital reception signal for two arbitrary elements among outputs of A / D converters provided for each antenna element is provided. A phase difference between the two elements is obtained using the time change rate of the phase difference and a target distance information to calculate a velocity of a target moving in a direction parallel to the radar, and a radar signal to be output to a target information processing unit at a subsequent stage. Processing method. 2. An array antenna for receiving radio waves from a target, a receiver for each antenna element of the array antenna, and an A / D converter for converting an analog reception signal output from each receiver into a digital signal. A digital beam forming unit for performing digital beam forming by using an output of the A / D converter as an input, a detecting unit for detecting a target from an output result of the digital beam forming unit, A phase calculator for calculating the phase at each time for the digital reception signal for any two elements of the output of the / D converter, and a time calculation between the two elements of the antenna based on the calculation result of each phase calculator for the two elements. A phase difference calculation unit for calculating a phase difference in the detection unit, a target distance information obtained by the detection unit, and a calculation result of the phase difference calculation unit. Calculate the speed of the target which moves in a direction parallel to over da, radar signal processing apparatus characterized by comprising a azimuthal velocity calculation unit for outputting the calculation result to the subsequent target information processing unit.