JP2007147534A - Radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration in the detection precision of target azimuth, caused by interfering a reflected wave from obstructing on the reflected wave from a target, when the distance between the target and the obstruction is smaller than distance resolution of a radar, by allowing the target and the obstruction to mix in a transmission beam. <P>SOLUTION: A radar system comprises a transmission beam controller for controlling the orientation of a transmission beam generated in each aperture face, in response to azimuth of the obstruction, by dividing the aperture face of an antenna device into two, a receiving beam controller for controlling the orientation of a receiving beam, independently of the transmission beam controlled with the transmission beam controller, and an obstruction detector for transmitting an existence direction of the obstruction to each part, when the obstruction enters the transmission beam controlled with the transmission beam controller. Thereby the orientation of partly overlapped two transmission beams relieves detection precision deterioration of the target azimuth by suppressing radio wave reflection from the obstruction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radar device that tracks a target.

  As a conventional radar apparatus, based on a plurality of M received signals received by a plurality of M antenna elements of an array antenna, a direction of each main beam of a predetermined plurality of N beams to be formed, and a reception frequency Calculates N beam electric field values, selects and outputs only the beam electric field values above the threshold value, and directs the main beam in the direction of arrival of the desired wave based on the output beam electric field value In addition, a plurality of N weights are calculated for the received signal so that the reception level in the arrival direction of the unwanted wave is zero, and the main beam is directed to the arrival direction of the desired wave based on each weight and the transmission frequency. The radiation pattern of the transmission signal is controlled by calculating and setting at least one of a plurality of M phase shift amounts and a plurality of M amplitude amounts with respect to the transmission signal that makes the transmission level in the arrival direction zero. The have already been disclosed (see Patent Document 1.).

JP-A-6-196921 (FIG. 1)

  For example, when a tracking helicopter approaches a mother ship trying to land, a conventional radar device irradiates a part of the radio wave transmitted in the direction of the helicopter to the mother ship, In some cases, the reflected signal from the aircraft and the reflected signal from the mothership were mixed. In such a case, the reflected signal from the mother ship with a large radar reflection area is much stronger than the reflected signal from the helicopter, so the reflected signal from the helicopter is buried in the reflected signal from the mother ship, and the position of the helicopter is detected. It becomes impossible. As described above, when the reflected signal from the target and the reflected signal from the obstacle are mixed in the received signal, there is a problem that the target position cannot be detected correctly.

  In view of such problems, the present invention provides a reflected wave from a target in the case where the target and the obstacle are mixed in the transmission beam and the distance between the target and the obstacle is closer than the distance resolution of the radar. The purpose is to prevent the deterioration of the detection accuracy of the target orientation even when the reflected wave of the interference occurs.

  The radar device according to the present invention inputs an antenna device configured by a plurality of element antennas and a plurality of transmission / reception modules, and obstacle position information from the outside, and based on its own installation position and reference orientation, If the obstacle is in the transmission beam and the target and the obstacle are at approximately the same distance, the obstacle existence direction is determined by the two transmission beam controllers and the above 2 Obstacle detectors that are sent from the obstacle detectors to the receiving beam controllers, and the direction in which the two transmission beams are generated at the respective aperture surfaces by dividing the aperture surface of the antenna device into two. Two transmit beam controllers that calculate the two transmit beams so that they always point in a line-symmetrical direction, with the line connecting the radar apparatus and the obstacle as the axis, The receive beam is directed to the target direction A, in which a two receive beam controller for calculating a reception directivity orientation.

  In the radar apparatus according to the present invention, the radio wave applied to the position where the obstacle is present has the same intensity in the transmission beam 1 and the transmission beam 2 and has the opposite phase so as to be erased from each other. When detecting, there is an effect that the obstacle does not have an adverse effect.

Embodiment 1 FIG.
FIG. 1 is a block diagram of a radar apparatus according to Embodiment 1 of the present invention, in which 1 is an antenna, 2 is a transmission / reception module, 3 is a beam controller for transmission, 4 is a beam controller for transmission, and 5 is for reception. A beam controller, 6 is a receiving beam controller, 7 is a transmitter, 8 is a receiver, 9 is an angle measuring processor, and 10 is an obstacle position detector.

The present invention relates to a radar device that tracks a target, and for example, irradiates an aircraft with radio waves and detects the position of the aircraft based on radio waves reflected from the aircraft.
In FIG. 1, a radar apparatus is installed on, for example, a ship or the seaside, and includes an antenna 1, a plurality of transmission / reception modules 2, a transmission beam controller 3, a transmission beam controller 4, and a reception unit. A beam controller 5, a receiving beam controller 6, a transmitter 7, a receiver 8, an angle measurement processor 9, and an obstacle position detector 10 are configured.

Next, the operation of the radar apparatus of FIG. 1 will be described.
The obstacle position detector 10 inputs the position information (latitude and longitude) of the obstacle from the outside, and sets its own installation position (latitude and longitude) and reference orientation (for example, the north direction is set to azimuth 0 and the horizontal plane direction is set to elevation angle 0) Based on the above, the distance to the obstacle and the direction in which the obstacle exists are obtained.

  When radio waves are transmitted in the direction of presence of the target being tracked, when the obstacle enters the transmission beam and is at the same distance, the obstacle position detector 10 determines the direction of presence of the obstacle by the beam controller for transmission. 3, the transmission beam controller 4, the reception beam controller 5, and the reception beam controller 6.

  In addition, when the radar device is mounted on a ship, the position, reference orientation, and horizontal plane inclination of the moving ship are measured by a GPS receiver, compass, level indicator (tilt meter), etc. mounted on the ship. The self installation position and the reference orientation can be easily obtained in advance.

  As for the position of the obstacle, position information can be obtained by a communication device in the case of a consort ship in which the obstacle is operated in cooperation. Further, when the obstacle is an island or a peninsula, the position information can be obtained from the map information.

  If none of the above is found, the position information of the obstacle can be obtained by performing a search with this radar apparatus.

The operation during transmission will be described below.
FIG. 2 is a diagram showing a transmission beam 1 and a transmission beam 2 according to Embodiment 1 of the present invention. The transmission beam controller 3 calculates the directional azimuth of the transmission beam 1 based on the input azimuth of the obstacle and the target azimuth being tracked.

  Here, as shown in FIG. 2, the transmission beam 1 is a beam formed by dividing the antenna 1 into left and right parts and opening the right side when viewed from the front. Similarly, the transmission beam controller 4 calculates the directional direction of the transmission beam 2 based on the input azimuth direction of the obstacle and the target azimuth being tracked.

  Here, as shown in FIG. 2, the transmission beam 2 is a beam formed by dividing the antenna 1 into left and right parts and forming an opening surface on the left side when viewed from the front.

FIG. 3 is a diagram for explaining the positional relationship among the radar apparatus, the target, the obstacle, and the beam pointing direction according to the first embodiment of the present invention.
A method of calculating the directivity directions of the transmission beam 1 and the transmission beam 2 by the transmission beam controller 3 and the transmission beam controller 4 will be described below.

Consider a case where the radar apparatus, the target, and the obstacle are in the positional relationship shown in FIG.
At this time, the transmission beam controller 3 sets the direction in which the target exists as the transmission direction of the transmission beam 1. The direction 1 in FIG. 3 is this transmission direction direction.

  Further, the transmission beam controller 4 obtains a position symmetrical to the target with the line connecting the radar apparatus and the obstacle as an axis, and sets the direction of this position as the transmission direction of the transmission beam 2. The direction 2 in FIG. 3 is this transmission direction direction.

  That is, the transmission azimuth is calculated so that the transmission beam 1 and the transmission beam 2 are always directed in a line-symmetrical direction with the line connecting the radar apparatus and the obstacle as an axis.

  The transmission beam controller 3 and the transmission beam controller 4 calculate the transmission directional directions of the transmission beam 1 and the transmission beam 2 as described above, and send the transmission directional directions to the transmission / reception module 2 and the angle measurement processor 9. To do.

  The transmitter 7 generates a high-frequency transmission signal and sends it to the transmission / reception module 2. The transmission / reception module 2 shifts the phase of the input high-frequency transmission signal for each transmission / reception module 2 so that the transmission beam is directed in the input transmission direction.

  At this time, the phase difference between the opening surface 1 and the opening surface 2 is set to 180 degrees. Since the transmission directivity is determined by the phase difference between the transmission / reception modules, the phase difference between the opening surface 1 and the opening surface 2 is set by setting the initial phase to 0 ° for the opening surface 1 and 180 ° for the opening surface 2, for example. Can be 180 degrees.

  The high-frequency transmission signal whose phase is shifted is transmitted to the antenna 1 after power amplification and is radiated from the antenna 1 into the air.

FIG. 4 is a diagram showing the reception beam 1 and the reception beam 2 according to the first embodiment of the present invention.
Next, the operation during reception will be described. The reception beam controller 5 calculates the reception directivity so that the reception beam 1 is directed to the target direction being tracked.

  Here, the reception beam 1 is a beam formed by dividing the antenna 1 into left and right parts and opening the right side as viewed from the front, as shown in FIG. Similarly, the reception beam controller 6 calculates the reception directivity so that the reception beam 2 is directed to the target direction being tracked.

  Here, the reception beam 2 is a beam formed by dividing the antenna 1 into left and right parts and opening the left side as viewed from the front, as shown in FIG.

  The antenna 1 receives the reflected radio wave from the target and sends a received signal to the transmission / reception module 2. The transmission / reception module 2 power-amplifies the reception signal, and then shifts the phase of the reception signal for each transmission / reception module 2 so that the reception beam is directed to the input reception direction.

The received signal whose phase is shifted is sent to the receiver 8.
The receiver 8 subtracts the synthesis result of the signal received at the aperture surface 2 from the synthesis result of the signal received at the aperture surface 1 to generate a difference signal. Also, the sum of the signals received on the aperture plane 1 and the signal received on the aperture plane 2 are added to generate a sum signal.
The receiver 8 performs amplification, frequency conversion, and phase detection on each of the sum signal and the difference signal, and sends it to the angle measurement processor 9.

  The angle measuring processor 9 receives the sum signal and the difference signal after phase detection, performs monopulse angle error detection processing, and detects the target azimuth. Here, the two transmission beams are axisymmetric about the obstacle, and the two reception beams are directed to the target direction.

  FIG. 6 is a diagram showing the relationship between the target orientation and the difference signal / sum signal in the monopulse angle measurement error detection process. The monopulse angle error detection process will be described below. The target orientation and the difference signal / sum signal have a relationship as shown in FIG. 6, for example.

  The direction of the horizontal axis is the amount of deviation from the center direction when the center direction of the received beam is 0 °. When the function representing this relationship is F (θ), if F (θ) is measured in advance, the target azimuth can be calculated backward from the difference signal / sum signal. Here, θ is a symbol representing the target orientation.

  That is, a difference signal and a sum signal can be generated from the reflected radio wave from the tracking target, and the target direction can be detected from the difference signal / sum signal using F (θ). This processing is called monopulse angle error detection processing.

  In this radar apparatus, F (θ) is measured in advance for each of the transmission directivity directions of the transmission beam 1 and the transmission beam 2, and the transmission directivity directions of the transmission beam 1 and the transmission beam 2 are input during target tracking. Monopulse angle error detection processing is performed by using F (θ).

  FIG. 5 is a diagram for explaining that the transmission beam 1 and the transmission beam 2 are erased from each other at the obstacle position according to the first embodiment of the present invention. FIG. FIG. 5B is a diagram showing the positional relationship of the transmission beam 2, and FIG.

  Since this radar apparatus operates as described above, as shown in FIG. 5A, the transmission beam 1 generated on the aperture surface 1 and the transmission beam 2 generated on the aperture surface 2 are simultaneously applied to the obstacle. Will be irradiated.

  The transmission directivity directions of the transmission beam 1 and the transmission beam 2 are controlled so as to be always directed in a line-symmetrical direction around the line connecting the radar apparatus and the obstacle, so that the position where the obstacle exists is irradiated. The transmission beam 1 and the transmission beam 2 have the same intensity.

  However, it is assumed that both the transmission beam 1 and the transmission beam 2 have a symmetrical beam pattern with respect to the beam center. Further, since the phase difference between the transmission beam 1 and the transmission beam 2 is controlled to be 180 degrees, the phase of the radio wave applied to the position where the obstacle is present is opposite to each other between the transmission beam 1 and the transmission beam 2. Become.

That is, the radio wave irradiated to the position where the obstacle exists has the same intensity and the opposite phase in the transmission beam 1 and the transmission beam 2 and disappears from each other. Therefore, the radio wave is not irradiated to this position.
This is shown in FIG.

  Therefore, in the present radar apparatus, the reflected wave from the obstacle can be suppressed, so that there is an effect that the obstacle does not adversely affect the detection of the target position.

  On the other hand, although the target is irradiated with both the transmission beam 1 and the transmission beam 2, the transmission beam 1 is directed to the target, whereas the transmission beam 2 is not directed to the target direction and is irradiated to the target. The intensity of the transmitted radio wave is larger in the transmission beam 1 than in the transmission beam 2.

For this reason, unlike the case of an obstacle, the transmission beam 1 and the transmission beam 2 are not erased from each other, and the reflected wave from the target can be received.
Therefore, the target azimuth can be detected by the monopulse angle measurement error detection process.

  In addition, every time the transmission direction azimuth of the transmission beam 1 and the transmission beam 2 changes, the monopulse angle error detection process is performed by changing F (θ), so that the transmission direction of the transmission beam 1 and the transmission beam 2 changes to the target direction. A detection error can be prevented from occurring.

It is a block diagram which shows the radar apparatus by Embodiment 1 of this invention. It is a figure which shows the transmission beam 1 and the transmission beam 2 by Embodiment 1 of this invention. It is a figure explaining the positional relationship of the radar apparatus by the Embodiment 1 of this invention, a target, an obstruction, and a beam directivity direction. It is a figure which shows the receiving beam 1 and the receiving beam 2 by Embodiment 1 of this invention. It is a figure explaining the transmission beam 1 and the transmission beam 2 by Embodiment 1 of this invention erasing each other in an obstacle position. It is a figure which shows the relationship between the target azimuth | direction and a difference signal / sum signal in a monopulse angle measurement error detection process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Antenna, 2 Transmission / reception module, 3 Transmitting beam controller, 4 Transmitting beam controller, 5 Receiving beam controller, 6 Receiving beam controller, 7 Transmitter, 8 Receiver, 9 Angle measuring processor, 10 Obstacle position detector.

Claims (2)

An antenna device including a plurality of element antennas and a plurality of transmission / reception modules;
Enter the obstacle position information from outside, find the distance to the obstacle and the direction of the obstacle based on its own installation position and reference direction, the obstacle enters the transmission beam, and the target and obstacle Are obstacle detectors that send the direction of obstacle presence to the two transmit beam controllers and the two receive beam controllers;
The antenna device is divided into two directions by dividing the aperture surface of the antenna device into two based on the direction of the obstacles received from the obstacle detector. Two transmit beam controllers for calculating so that the two transmit beams are always directed in the direction of line symmetry, with the line connecting the objects as axes;
Two receive beam controllers that calculate the receive orientation so that the receive beam is directed to the target orientation being tracked;
A radar apparatus comprising: 3. The radar apparatus according to claim 2, wherein the transmission beams from the two transmission beam controllers are generated so as to have the same intensity, opposite phase, and cancel each other.

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