JP2009002671A - Radar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an airborne radar device which is used for searching and tracking operations and reduces the ground clutter by controlling an antenna pattern in a minute computation time, in order to suppress incorrect detections such as a false detection, and incorrect tracking operations such as tracking clutters. <P>SOLUTION: The radar device being mounted on an aircraft and having a phased array antenna which can vary an antenna pattern by controlling a phase of an active module being a constituent, includes: a phase data storing memory having a phase table for previously storing phase data to be set in the active module for each roll angle, such that the antenna pattern of the phased array antenna has a low sidelobe on the earth surface side, when the attitude of the aircraft is controlled at an arbitrary roll angle; and a phase controlling section for setting the phase of the active module with phase data to be selected based on an input roll angle of the aircraft and to be read out of the phase table. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radar apparatus mounted on an aircraft.

In a radar apparatus having a phased array antenna type antenna, various antenna patterns can be selected and used by controlling the phase of each element.
An unnecessary signal suppression device that can generate an antenna pattern with a reduced side lobe level in the unwanted wave incident direction range is a receiver that converts an RF signal into an IF signal, and a digital in-phase / quadrature that converts an IF signal into a digital in-phase / quadrature signal From signal output means, digital multi-beam forming means for performing operations for forming a reception beam based on in-phase / quadrature signals, array manifold data storage means for storing previously acquired array manifolds, and output signals from the digital multi-beam forming means Select the load calculation means and the selection means to measure the unwanted wave incident direction range, read the array manifold from the array manifold data storage means, generate the virtual signal, calculate the correlation matrix and cross-correlation vector from the virtual signal and calculate the load A load coefficient multiplier that applies a load to the output signal It provided an adder for adding the signal of several units, and a subtractor for subtracting a sum signal from the output signal corresponding to the main beam direction of the digital multi-beam forming means (for example, see Patent Document 1).

JP 2005-148051 A

By the way, in radar equipment mounted on an aircraft having a phased array antenna, a pencil beam is normally used for searching and tracking. However, false detection and error are detected due to ground clutter received by the antenna side lobe of the pencil beam. Tracking occurs.
Therefore, the unnecessary signal suppression device proposed in Patent Document 1 can use an antenna pattern with a low sidelobe level in the ground clutter direction, but many calculations are performed for specifying the incident wave incident direction and calculating the antenna pattern. There is a problem that time is required.

  An object of the present invention is an aircraft that is used for search and tracking, and reduces ground clutter by controlling antenna patterns with a short calculation processing time in order to suppress false false detection and false tracking to clutter. It is to provide an on-board radar device.

  A radar apparatus according to the present invention includes a phased array antenna that is mounted on an aircraft and whose antenna pattern changes when the phase of an active module to be configured is controlled. The attitude of the aircraft is controlled to an arbitrary roll angle. Phase data storage in which phase data set in the active module is stored in advance for each roll angle so that the antenna pattern of the phased array antenna has a low side lobe on the ground surface side. A memory, and a phase controller configured to set the phase of the active module with phase data read from the phase table selected based on the input roll angle of the aircraft.

  The effect of the radar device according to the present invention is that the phase data of the active module in which the antenna pattern of the phased array antenna has low side lobes on the ground surface side is stored in advance in the phase table corresponding to the roll angle of the aircraft. Since the phase data is read from the phase table based on the input roll angle of the aircraft, and the phase of the active module is set based on the read phase data, the phase using the input roll angle is changed even if the attitude of the aircraft changes. It is only necessary to read out phase data stored in advance from the table, and the calculation processing time is short.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a radar apparatus according to Embodiment 1 of the present invention.
The radar apparatus 1 according to the first embodiment of the present invention is mounted on an aircraft, and data on the roll angle of the airframe is input from an inertial navigation apparatus 2 that governs the state of the airframe of the aircraft.
The radar apparatus 1 according to the first embodiment of the present invention includes an antenna 4 having a phased array antenna composed of an active module 3, and an excitation receiver that transmits a transmission signal to the antenna 4 and receives a reception signal from the antenna 4. 5. A signal processor 6 for transmitting a control signal for controlling the excitation receiver 5 so as to transmit the transmission signal to the antenna 4 and processing the reception signal from the excitation receiver 5 is provided.
In the radar apparatus 1 according to the first embodiment of the present invention, the phase controller 8 that controls the phase of the active module 3 and the phase data that controls each active module 3 are stored in advance for each roll angle of the airframe. A phase data storage memory 9 in which a phase table is stored is provided.

In Embodiment 1 according to the present invention, the roll angle of the airframe is divided into a plurality of regions divided by a predetermined angle, and the roll angle included in each region is represented by one roll angle in the region. Numbers are assigned to the representative roll angles.
As shown in FIG. 2, the phase data storage memory 9 stores a phase table for each roll angle representing a region. In the roll angle phase table representing the area, phase data that forms an antenna pattern as shown in FIG. 3 when the attitude of the aircraft is controlled to the roll angle included in the area is set for each active module 3. Yes.

When the signal processor 6 receives radio waves with the active module 3, the data of the roll angle of the fuselage input from the inertial navigation device 2 is included in the control signal and transmitted to the phase controller 8.
Is included in the control signal and transmitted to the phase controller 8.
When the active module 3 receives radio waves, the phase controller 8 obtains the roll angle area number received from the signal processor 6, and the phase corresponding to the area number of the phase data storage memory 9 based on the obtained area number. The phase data is read from the table, and the phase of each active module 3 is set with the read phase data.
The phased array antenna composed of the active module 3 shows an antenna pattern in which a low side lobe always exists on the ground surface side by the active module 3 having the phase set by the phase controller 8.

Next, the procedure of the search / tracking process by the radar apparatus according to the first embodiment of the present invention will be described with reference to the flowchart of FIG.
In step S101, a roll angle area number is obtained from the input roll angle of the machine body.
In step S102, a phase table corresponding to the obtained area number is selected.
In step S103, the phase data of each active module is read from the selected phase table.
In step S104, the phase of each active module 3 is set based on the read phase data. The phased array antenna composed of the set-phase active modules 3 has an antenna pattern in which low side lobes exist on the ground surface side.
In step S105, a radio wave is received using a phased array antenna having an antenna pattern having a low side lobe on the ground surface side, and search / tracking processing is performed.

  In the radar apparatus 1 according to the first embodiment of the present invention, the phase of the active module 3 in which the antenna pattern of the phased array antenna has low side lobes on the ground surface side is stored in advance in a phase table corresponding to the roll angle of the airframe. Since the phase data is read from the phase table based on the input roll angle of the aircraft and the phase of the active module 3 is set based on the read phase data, the input roll angle is changed even if the attitude of the aircraft is changed. It is only necessary to read out the phase data stored in advance from the phase table, and the calculation processing time is short. And since searching and tracking are performed using a phased array antenna having an antenna pattern with low side lobes on the ground surface side, false detection of false and tracking to clutter can be suppressed.

Embodiment 2. FIG.
FIG. 5 is a diagram showing a configuration of a radar apparatus according to Embodiment 2 of the present invention.
As shown in FIG. 5, the radar apparatus 1B according to the second embodiment of the present invention is different from the radar apparatus 1 according to the first embodiment in the signal processor 6B and the phase controller 8B. Similar parts are denoted by the same reference numerals, and description thereof is omitted.
The signal processor 6B according to the second embodiment according to the present invention is the same as the signal processor 6B according to the first embodiment except that a pattern change determination circuit 11 is added to the signal processor 6 according to the first embodiment. In addition to the roll angle of the aircraft, the altitude data of the aircraft is input from the inertial navigation device 2 to the signal processor 6B.

  When the active module 3 receives a radio wave, the pattern change determination circuit 11 receives a command signal for instructing to select a reference pattern when the altitude of the aircraft input from the inertial navigation device 2 is equal to or greater than a predetermined threshold. When the altitude of the aircraft input from the inertial navigation device 2 is less than a predetermined threshold, the roll angle data of the aircraft input from the inertial navigation device 2 is included in the control signal. Transmit to the phase controller 8B.

The phase controller 8B includes, as a reference pattern, the phase of the phased array antenna such that the phase of the active module 3 is such that the side lobe levels on the ground surface side and the ground surface side are equal as shown in FIG. It is remembered.
When the phase controller 8B receives the roll angle data from the signal processor 6B when receiving the radio wave with the active module 3, the phase controller 8B obtains the area number including the roll angle, and based on the obtained area number. The phase data is read from the phase table corresponding to the area number of the phase data storage memory 9, and the phase of each active module 3 is set with the read phase data.
Further, when receiving a command signal for selecting a reference pattern from the signal processor 6B, the phase controller 8B reads the phase data of the reference pattern and sets the phase of each active module 3 with the read phase data.

Next, the procedure of the search / tracking process by the radar apparatus 1B according to the second embodiment of the present invention will be described with reference to the flowchart of FIG.
In step S201, it is determined whether or not the input altitude of the aircraft is greater than or equal to a threshold value. If the altitude of the aircraft is greater than or equal to the threshold value, the process proceeds to step S202.
In step S202, phase data for each active module 3 is read from the reference pattern, and the process proceeds to step S206.
In step S203, a roll angle area number is obtained from the input roll angle of the machine body.
In step S204, a phase table corresponding to the obtained area number is selected.
In step S205, the phase data for each active module 3 is read from the selected phase table.
In step S206, the phase of each active module 3 is set based on the read phase data.
In step S207, a search / tracking process is performed by receiving radio waves using a phased array antenna having an antenna pattern with a low side lobe on the ground surface side or an antenna pattern without a low side lobe.

In the case of an antenna pattern in which a low side lobe exists on the ground surface side as in the first embodiment according to the present invention, the level of the side lobe on the side opposite to the reduced direction becomes high, and is unnecessary from an altitude higher than the own aircraft. Since it becomes easy to be influenced by waves, it is not preferable to have low side lobes on the ground surface side when the altitude of the aircraft is high enough not to be affected by clutter from the ground surface side.
Therefore, as in the second embodiment according to the present invention, when the altitude of the own aircraft is less than the threshold value, searching / tracking is performed by a phased array antenna having an antenna pattern in which a low side lobe always exists on the ground surface side. The influence of clutter from the ground surface side can be suppressed, and conversely, when the altitude of the aircraft is higher than the threshold value, it is searched and tracked by a phased array antenna having an antenna pattern that does not have low side lobes. Is less affected by clutter from the ground surface side, and is less susceptible to unwanted waves from higher altitudes.

Embodiment 3 FIG.
FIG. 8 is a diagram showing a configuration of a radar apparatus according to Embodiment 3 of the present invention.
As shown in FIG. 8, the radar apparatus 1C according to the third embodiment of the present invention is different from the radar apparatus 1B according to the second embodiment in that the signal processor 6C is the same. Reference numerals are added and description is omitted.
The signal processor 6C according to the third embodiment of the present invention is different from the signal processor 6B according to the second embodiment in the pattern change determination circuit 11C, and is otherwise the same. In addition to the altitude data of the aircraft input from the inertial navigation device 2, the pattern change determination circuit 11 </ b> C receives the reception signal of the target aircraft from the excitation receiver 5.

  When the active module 3 receives radio waves, the pattern change determination circuit 11C controls a command signal for instructing to select a reference pattern when the altitude of the aircraft input from the inertial navigation device 2 is equal to or greater than a predetermined threshold. And the altitude of the aircraft input from the inertial navigation system 2 is less than a predetermined threshold and the received signal to clutter ratio (hereinafter referred to as S / C ratio) is greater than or equal to a predetermined value. The command signal for instructing to select the reference pattern is included in the control signal and transmitted to the phase controller 8B, and the altitude of the aircraft input from the inertial navigation device 2 is less than a predetermined threshold and the S / C ratio is predetermined. When the value is less than the value, the roll angle data of the airframe input from the inertial navigation device 2 is included in the control signal and transmitted to the phase controller 8B.

FIG. 9 is a flowchart showing a procedure of search / tracking processing by the radar apparatus according to Embodiment 3 of the present invention.
Next, the procedure of the search / tracking process by the radar device 1C according to the third embodiment of the present invention will be described with reference to the flowchart of FIG.
In step S301, it is determined whether or not the altitude of the input aircraft is greater than or equal to a threshold. If the altitude of the aircraft is greater than or equal to the threshold, the process proceeds to step S302. If the altitude of the aircraft is less than the threshold, the process proceeds to step S303.
In step S302, phase data for each active module 3 is read from the reference pattern, and the process proceeds to step S307.
In step S303, it is determined whether or not the S / C ratio relating to the target aircraft is equal to or greater than a predetermined value. When the S / C ratio is equal to or greater than the predetermined value, the process proceeds to step S302, and when the S / C ratio is less than the predetermined value. Proceed to step S304.
In step S304, an area number of the roll angle is obtained from the roll angle of the input body.
In step S305, a phase table corresponding to the obtained area number is selected.
In step S306, phase data for each active module 3 is read from the selected phase table.
In step S307, the phase of each active module 3 is set based on the read phase data.
In step S308, radio waves are received using a phased array antenna having an antenna pattern with a low side lobe on the ground surface side or an antenna pattern without a low side lobe to perform search / tracking processing.

  The radar apparatus 1C according to the third embodiment of the present invention does not have a low side lobe in the antenna pattern of the phased array antenna when the S / C ratio related to the target aircraft is greater than or equal to a predetermined value. The large received signal from the target aircraft obtained means that the relatively small clutter from the ground surface side is not mistakenly tracked. Conversely, it is less susceptible to unwanted waves from higher altitudes than the aircraft itself.

Embodiment 4 FIG.
FIG. 10 is a diagram showing a configuration of a radar apparatus according to Embodiment 4 of the present invention.
As shown in FIG. 10, the radar apparatus 1D according to the fourth embodiment of the present invention is different from the radar apparatus 1 according to the first embodiment in the phase controller 8D and the phase data storage memory 9D, and is otherwise the same. The same reference numerals are attached to the same parts, and the description is omitted.
The phase data storage memory 9D stores a phase table corresponding to a predetermined number of roll angles. In the phase table of an arbitrary roll angle, phase data that forms an antenna pattern as shown in FIG. 3 when the attitude of the aircraft is controlled to an arbitrary roll angle is set for each active module 3.
The phase controller 8D is different from the phase controller 8 according to the first embodiment in that a linear interpolation unit 12 is added, and the rest is the same.
The linear interpolation unit 12 reads the phase data of the phase tables of two adjacent roll angles, which are provided with phase tables for the roll angles, input from the signal processor 6 from the phase data storage memory 9D. Further, a ratio between the difference between one roll angle and the roll angle input from the signal processor 6 and the difference between the two roll angles of the two phase tables is obtained. Next, for each active module 3, the phase data is calculated by linearly complementing the two phase data read from the two phase tables using the ratio obtained previously.

  By linearly complementing the phase data at adjacent roll angles in this way, even if the number of phase tables that can be stored in the phase data storage memory 9D is limited, the roll of the aircraft is not greatly increased. Accurate phase data corresponding to the corner can be acquired.

It is a figure which shows the structure of the radar apparatus by Embodiment 1 which concerns on this invention. It is a phase table for every roll angle stored in the phase data storage memory. The antenna pattern has low side lobes on the ground surface side. It is a flowchart which shows the procedure of the search and tracking process by the radar apparatus by Embodiment 1 which concerns on this invention. It is a figure which shows the structure of the radar apparatus by Embodiment 2 which concerns on this invention. This is an antenna pattern in which there is no low side lobe when the altitude of its own device is equal to or higher than the threshold. It is a flowchart which shows the procedure of the search and tracking process by the radar apparatus by Embodiment 2 which concerns on this invention. It is a figure which shows the structure of the radar apparatus by Embodiment 3 which concerns on this invention. It is a flowchart which shows the procedure of the search and tracking process by the radar apparatus by Embodiment 3 which concerns on this invention. It is a figure which shows the structure of the radar apparatus by Embodiment 4 which concerns on this invention.

Explanation of symbols

  1, 1B, 1C, 1D radar device, 2 inertial navigation device, 3 active module, 4 antenna, 5 excitation receiver, 6, 6B, 6C signal processor, 8, 8B, 8D phase controller, 9, 9D phase data Storage memory, 11, 11C pattern change determination circuit, 12 linear interpolation unit.

Claims (4)

In a radar apparatus including a phased array antenna that is mounted on an aircraft and that changes an antenna pattern by controlling the phase of an active module that is configured,
When the attitude of the aircraft is controlled to an arbitrary roll angle, the phase data set in the active module so that there is a low side lobe on the ground surface side in the antenna pattern of the phased array antenna, for each roll angle. A phase data storage memory for storing a pre-stored phase table;
A phase controller that sets the phase of the active module with phase data read from the phase table selected based on the roll angle of the aircraft that is input;
A radar apparatus comprising:   The phase control unit sets the phase of the active module with phase data read from the phase table selected based on the roll angle of the aircraft input when the altitude of the aircraft is less than a predetermined threshold; The radar apparatus according to claim 1, wherein the phase of the active module is set so that there is no low side lobe in the antenna pattern of the phased array antenna when the altitude of the aircraft is equal to or higher than a threshold value.   The phase control unit is selected from the phase table selected based on the roll angle of the aircraft that is input when the altitude of the aircraft is less than a threshold value and the ratio of the received signal from the target aircraft to the clutter is less than a predetermined value. The phase of the active module is set by the phase data to be read, and when the aircraft altitude is less than the threshold and the ratio of the received signal from the target aircraft to the clutter is greater than or equal to a predetermined value, the aircraft altitude is greater than the threshold or the aircraft The radar apparatus according to claim 2, wherein the phase of the active module is set so that there is no low side lobe in the antenna pattern of the phased array antenna when the altitude is equal to or greater than a threshold value.   The phase control unit is configured to roll the aircraft roll included between the two adjacent roll angles with the phase data of the two adjacent roll angles among the phase tables stored in the phase data storage memory. The radar apparatus according to claim 1, wherein the phase of the active module is set by phase data obtained by linear interpolation for each active module using an angle.

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