JP2576676B2 - Phased array radar device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phased array radar device that tracks a plurality of approach targets using a transmission pulse repetition period shorter than a target range delay time.

[Prior Art] FIG. 6 is a diagram showing the configuration of a conventional radar apparatus of this type. In the figure, (1) shows a transmitter, and (2) shows a transmission pulse signal generated by the transmitter (1). A transmitting pulse modulation circuit to be divided, (3) an array antenna, (4) an element antenna constituting the array antenna (3), (5) a phase shifter,
(6) is an amplifier, (7) is a duplexer, (8) is a receiver, (9) is a transporter (5), an amplifier (6), a duplexer (7) and a receiver (8). Transmitting and receiving module provided corresponding to the element antenna (4), (10)
Is a signal processor, which processes signals output simultaneously from the receivers (8) and discriminates received signals from different directions for each direction. A beam processor (11) is a signal processor. Phase shifters (5) required to form the transmit beam
2 is a phase shift amount calculation circuit for calculating the phase shift amount of the phase shift.

Next, a transmission pulse signal having a desired pulse repetition period (T ₁ + T ₂ ) whose operation will be described with reference to FIGS. 6 and 7 is generated by the transmitter (1) and input to the transmission pulse modulation circuit (2). Is done. As shown in FIG. 7, the transmission pulse modulation circuit (2) sets the target number of transmission pulse signals (here, four targets of A, B, C, and D).
Are divided into four sub-pulses (the pulse widths are all the same and τ) and supplied to each phase shifter (5), and the array antenna (3) is transmitted through the amplifier (6) and the transmission / reception switch (7). It is radiated from each of the constituent element antennas (4). At this time, as shown in FIG. 7, each phase shifter (5) has a phase shift amount φ _I to φ φ necessary to sequentially form four transmission beams in the radiation direction θ _A to θ _D of each sub-pulse. _m is calculated and set by the phase shift amount calculation circuit (12). In this way, each sub-pulse is emitted towards a separate target.

On the other hand, the reflected signal from each target is an array antenna (3)
And input to each transmitting / receiving module (9). In the transmission / reception module (9), the signal is input to the receiver (8) via the transmission / reception switch (7), converted into a digital video signal, and simultaneously transferred to a plurality (here, four) of beam forming circuits (10). The beam forming circuit (10) discriminates the received signal for each target direction by performing a discrete Fourier transform and outputs the discriminated signal to the signal processor (11). The received signal discriminated for each target direction is subjected to a well-known target detection process by a signal processor (11), and a distance R and a distance change rate V of each target are obtained.

[Problems to be Solved by the Invention] Since this type of conventional radar apparatus is configured as described above, when a transmission pulse repetition period shorter than a target range delay time is used, the reception signal and the transmission period are equal. However, there is a problem that the unreceivable time generated by the operation becomes long.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a phased array radar device capable of shortening the non-reception time for two specified specified targets.

Also, another invention of this invention is to
It is an object of the present invention to obtain a phased array radar device capable of reducing the non-reception time according to the priority.

[Means for Solving the Problems] The phased array radar apparatus according to the present invention is provided with a beam control circuit for controlling the radiation direction of each sub-pulse according to the distance change rate and range delay time of two specified specific targets. Things.

A phased array radar device according to another aspect of the present invention includes a target instruction circuit for assigning priorities to targets based on a distance change rate and a range delay time of a plurality of targets to be dealt with, and a command for the target instruction circuit. , A beam control circuit for controlling the radiation direction of each sub-pulse is provided.

[Operation] The phased array radar apparatus according to the present invention irradiates the first target in which the reception failure state occurs first with the sub-pulse positioned at the end of the transmission period, and sets the second target with the sub-pulse positioned second from the end. Immediately before the first target becomes incapable of receiving, the first target is irradiated with the sub-pulse located at the beginning of the transmission period, and simultaneously the second target is irradiated with the sub-pulse located at the end of the transmission period. If the second target goes through the unreceivable state and re-enters the receivable state during the continuation of the unreceivable state of the first target, the second target becomes the unreceivable state Immediately before, the non-reception time is shortened by irradiating with the first sub-pulse located at the beginning of the transmission period and irradiating the first target with the second sub-pulse located from the beginning.

The phased array radar device according to another aspect of the present invention assigns priorities in ascending order of time until an unreceivable state of each target occurs, and performs the same transmit beam control as described above to thereby control the unreceivable time. Is shortened corresponding to the priority.

An embodiment of the present invention will be described below with reference to the drawings. Note that the same components as those in the prior art are denoted by the same reference numerals and description thereof is omitted.

FIG. 1 is a block diagram showing one embodiment of the present invention.
Is a beam control circuit that controls the radiation direction of each sub-pulse according to the specified two target distance change rates and range delay time.

Next, the operation will be described with reference to FIGS. 1 to 3. FIGS. 2 and 3 show two specific targets designated by the target number of 4 as C.
And D, and the respective distance change rates are V _C and V _D , and show the case where D is the target in which the unreceivable state occurs first. Further, T ₁ is the transmit period or transmission pulse width, T ₂ is a receiving period. Here, as shown in FIG. 2A, the transmission pulse repetition period (T ₁ +
The transmission pulse signal of T ₂ ) is generated by the transmitter (1) and input to the transmission pulse modulation circuit (2). As shown in FIG. 2 (b), the transmission pulse modulation circuit (2) divides into four sub-pulses (pulse widths are all the same and τ) corresponding to the target number, and distributes and supplies them to each phase shifter (5). Then, the light is radiated from each element antenna (4) constituting the array antenna (3) via the amplifier (6) and the transmission / reception switch (7). In this case, the phase shift amount phi ₁ required for the m-number of the phase shifters (5) for forming a transmission beam of sequential four in the radial direction of each sub-pulse phi
_m is calculated and set by the phase shift amount calculation circuit (12). The order of transmission to each target, that is, the formation order of transmission beams, is determined by the beam control circuit (13), and the operation thereof will be described below.

Specified second target is C and D, 2 th because the target reception impossible state occurs earlier is D, transmits a first sub-pulses located at the end of the transmission period T ₁ with respect to the target D from the end Is transmitted to the target C. Since the targets A and B are arbitrary, each sub-pulse is transmitted here in the order of the targets A, B, C, and D. That is, the transmission beam is transmitted in the directions θ _A , θ _B , θ _C , θ _D during the transmission period T _1.
Are formed in this order. Now, the target sub-pulses leading edge of the received signal of the target D as shown in FIG. 2 (c) is located at the end of the transmission period T _1, as shown in FIG. 2 (b) in this state if they match the transmission period If the transmission continues to D, the unreceivable state caused by the overlap of the reception signal with the transmission period continues. The time ΔT during which the reception disabled state continues is that the target D moves after the leading edge of the reception signal of the target D matches the trailing edge of the transmission pulse signal, and the trailing edge of the reception signal matches the leading edge of the transmission pulse signal. It is time until it is expressed by the following formula.

Where C is the speed of light. Therefore, the beam controller (13)
Immediately before the reception signal from the target D coincides with the transmission period, the sub-pulse transmitted at the beginning of the transmission period with respect to the target D is transmitted as shown in FIG. Is transmitted to the target C, the received signal changes as shown in FIG. 2 (e). Therefore, the non-reception time ΔT _D of the target D in this case is expressed by equation (2).

Since 2τ <(T ₁ + τ), it is clear that ΔT _D <ΔT.

As time further elapses, the target C as shown in FIG.
If the leading edge of the received signal coincides with the transmission period, equation (3) is satisfied, or if equation (4) is satisfied in the state of FIG. 2 (e), FIG. 3 (c) As shown in (3), when the sub-pulse located at the beginning of the transmission period is transmitted to the target C and the sub-pulse located second from the beginning is transmitted to the target D, the phase shift amount calculation circuit is instructed to receive the third signal. It changes as shown in FIG.

T _D ≦ {T ₂ − (2τ + τ _G )} (3) Here, equation (3) is the third equation in the state of FIG. 3 (b).
As shown in FIG. 4C, when the second sub-pulse from the beginning of the transmission period is transmitted to the target D, the received signal of the target D does not match the transmission period. Equation (4) is the target D
Is a condition in which the target C returns to the receivable state through the non-receivable state within the time ΔT _D during which the non-receivable state continues,
The right side of the equation (4) is the time required for the leading edge of the reception signal of the target C to coincide with the trailing edge of the transmission pulse signal in FIG. 2 (e) and the time required for the target C as shown in FIG. This is the sum of the time until the unreceivable state of the target C is eliminated when the sub-pulse located at the beginning of the transmission period is transmitted.

By performing the transmission beam control described below, the non-reception time ΔTc of the target C is expressed by the following equation, and the non-reception time can be reduced in the same manner as in the case of the target D described above.

On the other hand, if the expression (3) or the expression (4) is not satisfied in the state of FIG. 3 (b), the current transmission beam control is maintained until the expression (3) is satisfied.

FIG. 4 is a block diagram showing an embodiment of another embodiment of the present invention, in which (1) to (12) are the same components as in the prior art. (13) is the same as the component of the phased array radar device of the present invention described above, and (1)
4) is a target instruction circuit for assigning a priority to each target based on the distance change rate and the range delay time of a plurality of targets to be dealt with.

Next, the operation will be described with reference to FIGS. 4 and 5. FIG. 5 shows a case where the targets to be dealt with are four targets of A, B, C, D, and the distance change of each target. The rates are V _A , V _B , V _C , V _D
It is. Further, a transmission pulse repetition period (T ₁ + T ₂ ) shorter than the target range delay time is used, and the fade array radar apparatus of the present invention shortens the non-reception time for the two specified targets. However, here, the target designating circuit (14) assigns a priority to each target, and determines a transmission order to each target, that is, a transmission beam formation order based on the priority. The priority order determination method is described below.

The priority order is the order of the shortest time before the reception signal from each target becomes incapable of receiving. Therefore, in FIG. 5, the above-mentioned margin times of the targets A, B, C, and D are set to T _MA , T _MB , T _MC , T
_{If it is MD} , it is expressed by the formula (9) from the formula (6).

Now, _assuming that T _MA <T _MB <T _MC <T _MD , the priorities of the respective targets are in the order of targets A, B, C, and D. Therefore, as shown in FIG. , C, and BA, and immediately before the target A enters the non-receivable state, each sub-pulse is transmitted in the order of the targets A, D, C, and B as shown in FIG. In this way, two higher-ranking targets are selected based on the priority of each target, and the same transmission beam control as in the case of the phased array radar apparatus of the present invention is performed.

[Effects of the Invention] As described above, the present invention provides a specific
By controlling the radiation direction of each sub-pulse according to the target distance change rate and the range delay time, there is an effect that the unreceivable time due to the reception signal being coincident with the transmission period can be reduced.

According to another aspect of the present invention, a priority is given to each target in accordance with a distance change rate and a range delay time of a plurality of targets to be dealt with, and a receiving direction is controlled by controlling a radiation direction of each sub-pulse based on the priority. There is an effect that the disabled time can be reduced according to the priority.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams of the operation of the present invention, and FIG. 4 is a block diagram showing another embodiment of the present invention. FIG. 5 is a diagram for explaining the operation of another invention of the present invention, FIG. 6 is a block diagram of a conventional radar device of this type, and FIG. 7 is a diagram for explaining the operation of this conventional radar device. 1) is a transmitter, (2) is a transmission pulse modulation circuit, (3) is an array antenna, (4) is an element antenna (5) is a phase shifter, (6) is an amplifier, (7) is a transmission / reception switch, (8) is a receiver, (9) is a transceiver module, (1)
0) is a beam forming circuit, (11) is a signal processor, (12) is a phase shift amount calculating circuit, (13) is a beam control circuit, and (14) is a target indicating circuit. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (2)

(57) [Claims] 1. A transmission pulse repetition period by forming a transmission beam directed in an arbitrary direction by controlling the phase of a transmission pulse signal using a phase shifter provided corresponding to each element antenna of an array antenna. In a phased array radar device that tracks an approach target having a longer range delay time, a transmission pulse modulation circuit that divides the transmission pulse signal into a plurality of sub-pulses according to a target number and supplies the sub-pulses to the phase shifter is designated. The first target, in which a reception failure occurs due to the overlap of the reception signal with the transmission pulse signal before the two targets, is irradiated with the sub-pulse located at the end of the transmission pulse signal and positioned at the second from the last. The second target is irradiated with the sub-pulse to be transmitted, and the first target is transmitted with the first sub-pulse of the transmission pulse signal immediately before the first target becomes incapable of receiving. Basically, the transmission beam is controlled so that the second target is irradiated with the sub-pulse located at the end of the transmission pulse signal at the same time as the irradiation of the target. When the second target is again in the receivable state after the transmission, the second target is irradiated with the first sub-pulse of the transmission pulse signal immediately before the second target becomes non-receivable, and the first target is irradiated with the second sub-pulse from the beginning. A beam control circuit, a phase shift amount calculating circuit for calculating a phase shift amount of the phase shifter necessary to form a transmission beam in a radiation direction of each of these sub-pulses, and a reflected signal from a target for each of the sub-pulses. And a plurality of beam forming circuits for forming a reception beam in the radiation direction of each sub-pulse through a receiver provided corresponding to each of the element antennas. Radar device. 2. A transmission pulse repetition period, wherein a transmission beam directed in an arbitrary direction is formed by controlling the phase of a transmission pulse signal using a phase shifter provided corresponding to each element antenna of an array antenna. In a phased array radar apparatus that tracks an approach target having a longer range delay time, a transmission pulse modulation circuit that divides the transmission pulse signal into a plurality of sub-pulses according to a target number and supplies the sub-pulses to the phase shifter; A target designating circuit for assigning priorities in the order of short time until an unreceivable state occurs and selecting the top two targets, a beam control circuit for controlling the radiation direction of each of the sub-pulses according to a command from the target designating circuit. A phase shift amount calculating circuit for calculating a phase shift amount of the phase shifter necessary to form a transmission beam in a radiation direction of each of these sub-pulses; A plurality of beam forming circuits for receiving a reflected signal from a target for each pulse via a receiver provided corresponding to each of the element antennas and forming a reception beam in a radiation direction of each sub-pulse apparatus.