JPH0695136B2 - Radar equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a radar device capable of simultaneously performing a search function and a tracking function.

[Conventional technology]

FIG. 4 shows a functional block diagram of a typical conventional radar device. In the figure, (1) is a transmitting / receiving antenna, (2) is a duplexer, (3) is a transmitter, and (4) is Is a receiver, (5)
Is a target detection circuit, (6) is a target tracking circuit, (7) is a beam scanning sequence circuit, and (8) is an antenna drive controller.

The conventional radar device is configured as described above, and the transmitting / receiving antenna (1) radiates microwave power into space, receives the reflected wave from the target, and passes through the duplexer (2) to the receiver. Enter in (4). The receiver (4) converts the received signal into a video signal and supplies it to the target detection circuit (5). The target detection circuit (5) determines the presence / absence of a target from the supplied video signal, converts target information such as the target distance, azimuth angle, and elevation angle into a digital signal and outputs the digital signal to the target tracking circuit (6).

The target tracking circuit (6) classifies and stores the input target information, establishes the target track and speed from the position information, and predicts and calculates the future position of the target at the next target tracking time. The predicted position and the tracking request are supplied to the beam scanning sequence circuit (7).

In addition, the beam scanning sequence circuit (7) forms a search sequence for searching the search coverage area, and at the same time, interrupts the tracking request from the target tracking circuit (6) to control the beam pointing direction for antenna drive control. Output to the transmitter (8), and at the same time, output transmission information (pulse width, PRT, hit count, etc.) to the transmitter (3). The antenna drive controller (8) drives the antenna in the designated beam pointing direction. Transmitter (3)
Generates microwave power required for target search and tracking, and supplies it to the transmitting / receiving antenna (1) via the transmission / reception switch (2).

In addition, the search frame time (time period required to search a predetermined spatial coverage) T _F of such a radar device is calculated by the following equation: time required for search T _S and time required for target tracking T _t
Is the sum of

T _F = T _S + T _t (1) T _t is also the number of pulse hits required for tracking n _t ,
It is determined by the product of the target tracking number N and the pulse repetition period (hereinafter referred to as PRT _t ) required for target tracking.

_{T t = N · n t ·} PRT t ...... (2) T S is also, of search Coverage as follows beam spot number n _s,
And the pulse repetition period (hereinafter referred to as PRT _s ) required for searching.

T _s = N _B · n _s · PRT _s (3) where N _B is the search coverage Ω and the search beam width θ _B as follows.
Will be decided at.

N _B = η ・ Ω / θ _B ² (4) where η is an array coefficient determined by the beam array.

[Problems to be Solved by the Invention]

In the radar device as described above, since the search frame time T _F is constant, when the number of pulse hits n _t is increased to improve the tracking accuracy (because the tracking accuracy is inversely proportional to n ^1/2 ), Alternatively, when the tracking target number N increases, the tracking time T _t increases, so that the search time T _S is reduced and the search coverage area is omitted. Alternatively, if T _t is constant, the number N _t of tracking pulse hits decreases as N increases, so
There is a problem that the tracking accuracy deteriorates.

The present invention has been made in order to improve such a problem. When the required tracking accuracy is tried to be secured, the tracking time T _t increases and the search time T _S decreases as the tracking target number N increases. In order to prevent the search beam from falling out, the search beam array interval is widened, that is, the array coefficient η is changed, and the search beam spot number N _B is reduced to reduce the set coverage area T _S. Search within. In other words, the objective is to simultaneously achieve the required tracking accuracy and prevent the search coverage area from decreasing.

[Means for Solving the Problems]

The radar device according to the present invention includes a "beam spot number calculation circuit" for calculating the number of beam spots that can be searched from the search time reduced according to the number of tracking targets, and a search beam so that the beam spots have a constant arrangement interval. A "search beam coordinate calculation circuit" for calculating spatial coordinates is added.

[Action]

In the present invention, unlike the conventional radar system that searches and tracks with a fixed beam spot array, a desired search area is maintained, and a target search is performed with a search beam spot array that changes according to the number of tracking targets. Therefore, it is possible not only to prevent the search coverage area from decreasing due to tracking, but also to improve the tracking accuracy.

〔Example〕

FIG. 1 shows an embodiment of the present invention (1) to (8)
Is the same as the above conventional device, (9) is the number of beam spot calculation times, and (10) is the search beam coordinate calculation circuit. The beam spot number calculation circuit (9) calculates the number of beam spots that can be searched in the assigned search time and inputs it to the search beam coordinate calculation circuit (10). The search beam coordinate calculation circuit (10) calculates the array interval from the number of search beam spots for the search coverage area, calculates the position coordinates, and outputs it to the beam scanning sequence circuit (7).

In the radar device configured as described above, in the beam spot number calculation circuit (9) from the target newly detected by the target detection circuit (5) and the target already managed by the target tracking circuit (6) , Equations (1) and (2) are used to calculate the search time as shown in the following equation.

T _S = T _F −T _t = T _F −n _t · PRT _t …… (5) Moreover, the number of search beam spots is calculated from Eqs. (3) and (5) as follows.

However, in Eq. (6), T _F , n _t , PRT _t , n _S , and PRT _S are determined by the radar device, and therefore N _B is determined if N is open.

Beam coordinate calculation circuit that searched N _B calculated by Eq. (6) (10)
By inputting into, it becomes possible to easily form a search beam array according to the number of tracking targets.

At this time, the array coefficient η becomes the following equation from Eqs. (4) and (6).

Therefore, compared to the conventional method of irradiating a beam with a constant search frame time, it is possible to greatly improve the problems such as the decrease of the search coverage area due to the increase of the time T _t required for target tracking or the deterioration of tracking accuracy. Become.

This is shown in FIG. 2, taking as an example the case where a conical beam is scanned over the search coverage in a hemispherical space.

FIG. 2 (A) is a search coverage diagram showing that search and tracking are performed simultaneously when the tracking target is 1, and FIG. 2 (B) is searched when the tracking target increases to 4 The beam coordinate of is recalculated, the interval of the beam arrangement is expanded, and the search coverage area is prevented by the present invention. In FIG. 2 (C), the tracking target is increased to 4, Although the search time is reduced by the increase of the tracking time, the required search time per one beam spot is the same, and thus the search coverage area in the conventional method in which the search coverage area is omitted is shown. However, the location where the search omission occurs can be set arbitrarily. In the figure, (a) is the search beam spot, (b) is the tracking beam spot, and (c) is the missing part of the search coverage area due to the conventional tracking.

This is shown in FIG. 3 by taking as an example the time allocation of the search and the tracking within the search frame time with respect to the increase or decrease of the target number.

Fig. 3 (A) is a time distribution of search and tracking when the tracking target is 1, Fig. 3 (B) is a time distribution of search and tracking when the tracking target is 4, and Fig. 3 (C) is tracking. For pulse hit number n _t
32 is a time chart when the number of search pulse hits n _{S is set} to 4.

At this time, the number of search beam spots N _B1 and N _B2 has the following relationship.

N _B1 > N _B2 (8) Here, for simplicity, tracking and search are separated regardless of the order of beam scanning, but the order of tracking is random according to the position of the target. .

Further, FIG. 3 also explains how to suppress an increase in search frame time due to an increase in the number of tracking targets in the conventional method.

〔The invention's effect〕

As described above, the present invention adds a mechanism for calculating the number of searchable beam spots corresponding to the number of generated tracking targets, and a mechanism for recalculating the coordinates of the beam spots to add a search coverage area for target tracking. This not only suppresses the decrease in the noise, but also maintains the required tracking accuracy.

[Brief description of drawings]

FIG. 1 is a system block diagram showing an embodiment of the present invention, FIG. 2 (A) to FIG. 2 (C) are views for explaining the action and effect of the present invention, and FIG. 3 (A) to FIG. FIG. 3 (C) is a diagram for explaining distribution of search time and tracking time, and FIG. 4 is a system block diagram of a conventional radar device. In the figure, (1) is a transmitting / receiving antenna, (2) is a duplexer, (3) is a transmitter,
(4) receiver, (5) target detection circuit, (6) target tracking circuit, (7) beam scanning sequence circuit, (8) antenna drive controller, (9) beam spot number calculation circuit , (10) is the search beam coordinate calculation circuit, (a) is the search beam spot,
(b) is the beam spot for tracking, (c) is the missing part of the search beam spot due to tracking occurring in the conventional method, (d)
Is the tracking time per target, (e) is the search time per search beam spot, (f) is the tracking pulse, (g)
Is a search pulse. The same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A transmission / reception antenna for radiating and receiving radio waves, a receiver for receiving a reception wave from the transmission / reception antenna, a target detection circuit for detecting a target from a video signal of the receiver, and the target detection. A target tracking circuit for managing the target information newly detected from the circuit, a means for calculating the time allowed for the search from the target information from the target tracking circuit, the allowed time, the search coverage area, and the transmission repetition A radar device comprising: means for calculating the number of searchable beam spots from the cycle; and means for calculating search beam coordinates from the number of beam spots to form a search pattern.