JPH06317653A - Radar equipment - Google Patents

Abstract

PURPOSE:To provide a radar equipment capable of shortening the search frame time while maintaining distance performance by a pencil beam transmitting and receiving making use of the advantage of received multiple beams formed by digital beam formation (DBF). CONSTITUTION:A radar device has a transmitting antenna 10 and a receiving array antenna 11 individually. The transmitting antenna 10 transmits pencil beams (P1-Pn) continuously in plural directions respectively with pulse width (T1-Tn) in one PRI and with frequency (f1-fn)/modulation (M1-Mn) (RBS (random burst search) transmission). The receiving antenna system has band-pass filters BF1-BFn for preventing transmitting-receiving interference in compliance with the transmit pulse frequency so as to execute digital beam formation for forming received pencil multiple beams with directionality in the continuously transmitted direction to the post-stage and null in the direction of the transmitting antenna. Demodulation corresponding to the modulation at the transmitting time in the direction of each beam is then executed by a demodulator 16.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art FIG. 8 shows the structure of a conventional digital beam forming radar apparatus. In FIG. 4, 1 is an array antenna for transmitting and receiving radio waves, and t1 to tm are elements of the array antenna. A transceiver for frequency-converting and amplifying a microwave reception signal into a video signal and generating a microwave signal, and 3 a digital beam former for beam forming from a video signal output from the receiver,
4 is S / N improvement by the formed reception beam signal, S / N
A multi-beam signal processor 5 for performing C improvement, target detection, angle measurement / distance measurement, tracking data processing, etc. is a transmission beam controller for controlling the transmission beam direction.

Beam control in this conventional DBF radar device is performed by the method shown at timings A1, A2, and A3 in FIG. That is, like the timing A1, the pencil beam is used for both transmission and reception, as is often seen in the conventional phased array radar. As in the timing A2, the fan beam is transmitted and the pencil multi-beam is received. As at the timing A3, a fan beam is transmitted and a pencil multi-beam is received, and long-term integration is performed in the pulse repetition direction to further secure distance performance.

[0004]

In the conventional DBF radar device, transmission is performed at timing A2 as a beam control method for effectively utilizing the reception multi-beam of DBF as compared with the beam control similar to the phased array shown at timing A1. The frame time was shortened by using a fan beam. However, in general, there is a problem that when the transmission is a fan beam, the antenna gain is lowered and the distance performance is deteriorated. Therefore, it is necessary to perform integration for a long time in order to maintain the distance performance even if the transmission is a fan beam as in the timing A3. As a result, when the distance performance is made equal to that of the pencil beam transmission, the frame time is also pencil. There was a problem that it became as large as beam transmission.

The present invention utilizes the multi-beams for reception, which is a feature of the DBF radar device, and shortens the search frame time corresponding to the transmission fan beam and the distance performance equivalent to the pencil beam transmission / reception in the conventional phased array radar. It aims to overcome the conflicting problems of getting.

[0006]

The present invention has a transmitting antenna and a DBF receiving antenna separately, and the transmitting antenna has one antenna.
Pulse repetition period (PRI)
pulse transmission in different directions in the signal interval, and in the DBF receiving antenna system, the received multi-beams are transmitted in multiple directions after passing through a band filter to prevent interference between the target reflected wave and the transmitted direct wave. It is designed to be formed.

According to the present invention, in addition to the band-pass filter, in order to further reduce the interference between the target reflected wave and the transmitted direct wave, the digital beam former is operated by using the weighting for forming the null beam toward the transmitting antenna during the beam forming. It is the one.

According to the present invention, in addition to changing the transmission frequency for each pulse, the modulation pattern is changed, and after the beam formation, the signal modulated according to the beam direction is demodulated.

[0009]

The radar apparatus according to the present invention has a transmitting antenna and a receiving antenna separately, and the transmitting antenna has each pulse width (T) within one PRI as shown at timing A4 in FIG.
1 to Tn) pencil beam in multiple directions (P1 to Pn)
Continuous transmission (RBS transmission (random bursts) at each frequency (f1 to fn) / each modulation (M1 to Mn).
The receiving antenna system has a bandpass filter to prevent transmission / reception interference according to the transmission pulse frequency, and has a directivity in the subsequent transmission direction and a reception pencil with a null in the transmission antenna direction. Digital beam forming for forming a multi-beam is performed, and then demodulation corresponding to modulation during transmission in each beam direction is performed.

[0010]

【Example】

Example 1. FIG. 1 shows an embodiment of the present invention,
Reference numerals 3 and 4 are exactly the same as those of the conventional apparatus. Reference numeral 11 is an array antenna dedicated to reception, 7 is a switching network for switching connection between a reception microwave signal from the array antenna and a band filter of BF1 to BFn,
9 is a switching network for distributing the microwave signal output from the band-pass filter to the receivers r1 to rm corresponding to the array elements, 6 is a switching network 7,
A reception timing controller for controlling the timing of the switching network 9, 10 is a transmission antenna dedicated to transmission,
Reference numeral 12 is a transmitter capable of switching frequencies f1 to fn and transmitting within one PRI, and reference numeral 13 is a transmission beam controller for controlling the direction and frequency of transmission.

The operation of the radar device thus configured will be described. In the transmitting antenna system, the transmitter 12 having the transmitting frequencies f1 to fn causes the transmitting beam controller 13 to set the pencil beam direction P1 with the pulse width T1 from the pulse transmission trigger in the L-PRF mode as shown at timing A4 in FIG. A radio wave is transmitted by the transmitting antenna 10 at a frequency of f1 and then a pencil beam direction P is obtained with a pulse width T2.
2 at the frequency f2, and sequentially in another direction at another frequency. The number of pulses that can be transmitted at this time can be up to the transmittable duty of the transmitter in the PRI. In this way, continuous transmission is possible while changing the transmission direction.
It is called "ndom burst search".

On the other hand, although the receiving antenna system also operates in synchronization with the transmission trigger, the microwave signal received by the receiving antenna 11 is transmitted at the transmission timing T1 (beam direction P).
In the case of 1), the switching network 7 is controlled so as to be input to the bandpass filter BF1 that does not pass the frequency band transmitted at T1. Similarly, transmission timing Tn
In the case of (beam direction Pn), the switching network 7 is controlled so as to be input to the bandpass filter BFn that does not pass the frequency transmitted at Tn. In this way, the microwave signal from each array element that passes through the reflected wave from the target and passes through the band filter for preventing the interference of the direct wave from the transmitting antenna 10 is received by the switching network 9 by the receivers r1 to rm corresponding to each array element. Entered in. In this way, the microwave signal received by each array element is prevented from directly leaking the transmission power into the receiving system and input to the digital beam former 3. By performing discrete Fourier transform in the digital beam former 3, reception multi-beams are simultaneously formed in the direction of P1 to Pn transmitted in time division. Further, the formed reception beam is corrected for the time difference of the transmission timing, and the multi-beam signal processor 4
Is input to S / N improvement, S / C improvement, target detection, angle measurement /
Radar signal processing such as distance measurement and tracking data processing is performed.

Example 2. 2 shows Embodiment 2 of the present invention, in which 1, 3 to 13, BF1 to BFn, r1 to
The rm is exactly the same as the device of the first embodiment. 1
Reference numeral 4 is a beam forming weight that forms a null in the direction of the transmitting antenna during beam forming.

The operation of the radar device thus configured will be described. The procedure is the same as that of the first embodiment up to the transmission of radio waves and the formation of beams in the reception system. In this embodiment, in order to reduce the interference between the target reflected wave and the transmitted direct wave, the null beam forming previously measured and held so as to form a null in the direction of the transmitting antenna in the receiving multi-beam forming during transmission during beam forming. The output from the weight 14 is used to form a beam. That is, as shown in FIG. 5, the weight of W12 is used in the T2 section of the reception beam 1 (P1 direction). W12 is a weight that directs the beam in the P1 direction and forms a null in the transmitting antenna direction with respect to the frequency f2. Similarly, W23 is P2
A weight that directs the beam in the direction and forms a null in the direction of the transmission antenna with respect to the frequency f3. By thus forming the beam, the direct transmission wave is suppressed in frequency, and in addition, the direct transmission wave is also suppressed in the incident direction of the receiving antenna at the time of forming the beam, thereby reducing interference with the target reflected wave. Thereafter, similar to the first embodiment, the multi-beam radar signal processor 4 performs signal processing such as detection.

Example 3. FIG. 3 shows Embodiment 3 of the present invention, in which 1, 3 to 14, BF1 to BFn, and r1 to
The rn is exactly the same as the device of the second embodiment. 1
Reference numeral 5 denotes a modulator that adds different modulations (M1 to Mn) to the transmission wave for each transmission pulse (T1 to Tn) at the time of transmission, and 16 is a demodulator for demodulating the reception waves that are differently modulated according to the beam directions. .

The operation of the thus constructed radar device will be described. In the transmission of the electric wave, the electric wave is transmitted at the pulse width T1 in the pencil beam direction P1 at the frequency f1 as shown in the timing A6 of FIG. 6 at the frequency M1, and then modulated at the frequency f2 in the pencil beam direction P2 with the pulse width T2. M2 is transmitted, and then sequentially transmitted in different directions with different frequencies and different modulations. The receiving system is the same as that of the second embodiment until after beam formation, but thereafter, the modulated wave of M1 in the P1 direction and M2 in the P2 direction is demodulated corresponding to the beam. At this time, even if a modulated wave component other than M1 is mixed in the P1 direction beam due to interference, it is further suppressed by the correlation processing by demodulation. In this way, the transmission direct wave is suppressed in frequency by performing demodulation corresponding to the beam, and in addition to suppressing the transmission direct wave in the incident direction of the receiving antenna at the time of beam formation, in addition to the correlation processing modulation method at the time of demodulation, The interference with the target reflected wave is further reduced.
Thereafter, similar to the first and second embodiments, the multi-beam radar signal processor 4 performs signal processing such as detection.

[0017]

The present invention has the effects as shown in FIG. 7 by being configured as described above. That is, by using a transmitting antenna and a receiving antenna individually, performing pulse transmission in a plurality of directions within one pulse repetition period, forming reception multi-beams in those directions, and performing signal processing, the antenna gain of transmission and reception by a pencil beam is increased. That is, there is an effect that the search frame time can be reduced by being able to search in a plurality of directions at a time without deterioration of the distance performance such as fan beam transmission during reception multi-beam.

[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 third embodiment of the present invention.

FIG. 4 is a timing chart showing beam control of the radar device according to the first embodiment of the present invention.

FIG. 5 is a timing diagram showing beam control of the radar device according to the second embodiment of the invention.

FIG. 6 is a timing diagram showing beam control of the radar device according to the third embodiment of the invention.

FIG. 7 is a diagram showing an effect of the radar device of the present invention.

FIG. 8 is a block diagram showing a conventional radar device.

FIG. 9 is a timing diagram showing beam control of a conventional radar device.

[Explanation of symbols]

 1 array antenna t1 transceiver tm transceiver 3 digital beam former 4 multi-beam signal processor 5 transmission beam controller 6 reception timing controller 7 switching network 9 switching network BF1 bandpass filter BFn bandpass filter r1 receiver rm receiver 10 transmission Antenna 11 Receiving array antenna 12 Transmitter 13 Transmit beam controller 14 Null beam forming weight 15 Modulator 16 Demodulator

Claims (3)

[Claims] 1. A transmitter for generating a radar transmission signal,
An array antenna for transmitting the transmission signal generated by the transmitter to the space, a transmission beam controller for controlling the timing of this transmission, a reception array antenna for receiving the reflection signal from the target transmitted to the space, A switching network that selects a band filter that limits the microwave signal received from each element of this receiving array antenna, a band filter that does not pass a specific frequency band, and the microwave signal output from this band filter that is received by the array element. Switching network to distribute to the equipment, receiver group that frequency-converts and amplifies the microwave signal corresponding to each array element into a video signal, and the output video signal of this receiver group is input and multi-beam by discrete Fourier transform Beam forming device for forming a beam, and an output of the digital beam forming device Radar system for a multi-beam signal processor, characterized in that a reception timing controller for controlling the two switching network that handles radar signal No.. 2. A transmitter for generating a radar transmission signal,
An array antenna for transmitting the transmission signal generated by the transmitter to the space, a transmission beam controller for controlling the timing of this transmission, a reception array antenna for receiving the reflection signal from the target transmitted to the space, A switching network that selects a band filter that limits the microwave signal received from each element of this receiving array antenna, a band filter that does not pass a specific frequency band, and the microwave signal output from this band filter that is received by the array element. A switching network to be distributed to the machine, a group of receivers for frequency-converting and amplifying a microwave signal corresponding to each array element into a video signal, and a null beam forming weight for holding a weight for forming a null beam in the transmitting antenna direction, Input the output video signal of the receiver group to form a null beam forming window. Discrete using the site,
It is equipped with a digital beam former for forming a multi-beam by Fourier transform, a multi-beam signal processor for processing a radar signal of an output signal of the digital beam former, and a reception timing controller for controlling the two switching networks. A radar device characterized by the above. 3. A modulator for generating a transmission modulation signal of a radar, a transmitter for synthesizing and amplifying a transmission reference signal and the transmission modulation signal, and transmitting the transmission signal generated by the transmitter to space. Array antenna, a transmit beam controller that controls the timing of this transmission, and a receive array antenna that receives the reflected signal from the target transmitted to space,
A switching network that selects a band filter that limits the microwave signal received from each element of this receiving array antenna, a band filter that does not pass a specific frequency band, and the microwave signal output from this band filter that is received by the array element. A switching network to be distributed to the machine, a group of receivers for frequency-converting and amplifying a microwave signal corresponding to each array element into a video signal, and a null beam forming weight for holding a weight for forming a null beam in the transmitting antenna direction, A digital beam former which inputs the output video signal of the receiver group and forms a multi-beam by the discrete Fourier transform using a null beam forming weight, and is modulated corresponding to the formed beam in this digital beam former. The demodulator that demodulates the signal and this demodulator Radar system for a multi-beam signal processor of a force signal processing radar signals, characterized in that a reception timing controller for controlling the two switching networks.