Radar device and method for processing its radar signals

Abstract

Appropriate clutter removal processing is performed according to the target's location, enabling effective suppression of false target detections. [Solution] In the radar device of the embodiment, map information including the user's position and at least divided into land and sea areas is stored, a map is displayed based on the map information, the user's position and true north information, and target symbols indicating detected targets are superimposed on the map based on target information obtained from the received digital signal. The display unit acquires land / sea type information of the area where the target symbols are superimposed, and if it is land, ground clutter removal processing is selected and executed, and if it is sea, sea clutter removal processing is selected and executed.

Description

Technical Field

[0001] The present embodiment relates to a radar apparatus and a radar signal processing method therefor. Background Art

[0002] A radar apparatus transmits radar waves, receives and detects radar reflected waves reflected from a flying target, and detects the position of the target as viewed from the receiving point. In recent years, not only flying objects flying over land / sea / low altitude / high altitude, but also space debris orbiting the Earth and gliding vehicles flying at high speed (hereinafter referred to as "targets") have become detection targets.

[0003] This radar apparatus includes a clutter removal processor such as an MTI (Moving Target Indicator), which removes clutter signals contained in received signals and suppresses false detection of targets caused by clutter. Further, the radar apparatus stores, in a display device, map information of a three-dimensional reference coordinate system including a pre-registered installation point of the apparatus itself, displays a map on the display device based on the map information, and superimposes and displays the self-position, true north direction, target position, and the like on the map.

[0004] However, different types of clutter, for example ground clutter and sea clutter, have different characteristics of clutter signals. Clutter removal processing intended for ground clutter removal is effective for ground clutter removal, but cannot achieve a removal effect for sea clutter, and vice versa. For this reason, in conventional radar apparatuses, an operator confirms the position of a target of interest on a map, determines whether the position is on land or sea, and selectively switches between ground clutter removal processing and sea clutter removal processing according to the determination result. Prior Art Documents Patent Documents

[0005] Patent Document 1 Japanese Unexamined Patent Publication No. 2001-99920 Patent Document 2 Japanese Patent Publication No. 2023-89649 [Overview of the project] [Problems that the invention aims to solve]

[0006] As described above, conventional radar systems have the challenge of requiring operators to confirm the location of the target on a map, determine the type of area to which that location belongs, and then switch to clutter removal processing according to the determination result.

[0007] This embodiment has been made in view of the above problems, and aims to provide a radar device and a radar signal processing method that can perform appropriate clutter removal processing according to the position of the target and appropriately suppress false detection of the target. [Means for solving the problem]

[0008] To solve the above problems, in the radar device according to the embodiment, the antenna unit forms a search beam in the indicated direction and emits a transmit RF signal, receives the reflected signal, the transmitting unit generates the transmit RF signal and outputs it to the antenna unit, the receiving unit converts the signal received by the antenna unit into a baseband received digital signal, the signal processing unit performs clutter removal processing on the received digital signal and then performs target detection processing to generate target information including the azimuth angle, elevation angle, and distance of the detected target, the control unit generates a beam control signal indicating the initial direction of the search beam formation and outputs it to the antenna unit, then calculates the beam directivity angle for the detected target based on the target information obtained by the signal processing unit, generates a beam control signal indicating the direction of the search beam formation based on this beam directivity angle and outputs it to the antenna unit, and outputs it to the transmitting unit. The system outputs a transmission control signal that instructs the transmission schedule of the transmitted RF signal, the self-position detection unit receives positioning signals from multiple satellites to detect its own position and generate true north information, the display unit stores map information that includes its own position and divides at least land and sea areas, displays a map based on the map information and the self-position and true north information obtained by the self-position detection unit, and overlays target symbols indicating the detected targets on the map based on the target information obtained by the signal processing unit, the signal processing unit includes at least ground clutter removal processing and sea clutter removal processing as clutter removal processing, acquires area type information from the display unit on which the target symbols are overlaid, selects ground clutter removal processing if the area is land, and selects sea clutter removal processing if the area is sea to be executed.

[0009] Furthermore, in the radar device according to the embodiment, the display unit acquires altitude information of the detected target from the target information and displays the altitude near the target symbol, and outputs altitude classification information. The signal processing unit further calculates the altitude from the azimuth angle, elevation angle, and distance and includes it in the target information. The clutter removal process includes altitude-specific weather clutter removal processing, and selectively executes the altitude-specific weather clutter removal processing based on the altitude classification information output from the display unit. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a block diagram showing the configuration of a radar system according to an embodiment. [Figure 2] Figure 2 shows an example of the display of a map including the radar device's own position, radar information, selected target information, and target list in an embodiment. [Figure 3] Figure 3 shows the application areas and detection results for land / sea information from map information and ground clutter / sea clutter removal processing in the range direction, respectively, in an embodiment. [Figure 4] Figure 4 is a flowchart showing the process flow of automatic switching control for area determination and clutter removal processing of the received digital signal in an embodiment. [Modes for carrying out the invention]

[0011] The embodiments will be described below with reference to the drawings.

[0012] Figure 1 is a block diagram showing the configuration of a radar device according to an embodiment. In Figure 1, the antenna unit 1 forms a search beam in the indicated direction and emits a transmit RF signal, and receives the reflected signal. The transmitting unit 2 generates a transmit RF signal and outputs it to the antenna unit 1. The receiving unit 3 converts the RF signal received by the antenna unit 1 into a baseband received digital signal. The signal processing unit 4 performs clutter removal processing on the received digital signal and then performs target detection processing to generate target information including the azimuth angle, elevation angle, and distance of the detected target.

[0013] The control unit 5 generates a beam control signal that indicates the direction in which the initial search beam should be formed and outputs it to the antenna unit 1. Subsequently, based on the target information obtained by the signal processing unit 4, it calculates the beam directional angle relative to the detected target, and generates a beam control signal that indicates the direction in which the search beam should be formed based on this beam directional angle and outputs it to the antenna unit 1. Meanwhile, it outputs a transmission schedule signal that indicates the transmission schedule for the transmitted RF signal to the transmission unit 2.

[0014] The self-position detection unit 6 receives GPS (Global Positioning System) signals or GNSS (Global Navigation Satellite System) signals from multiple satellites to detect its own position and generate true north information.

[0015] The display unit 7 stores map information that includes its own position and at least distinguishes between land and sea areas. Based on this map information and the self-position and true north information obtained by the self-position detection unit 6, it displays a map and overlays target symbols indicating detected targets based on the target information onto the map.

[0016] The signal processing unit 4 includes ground clutter removal processing, sea clutter removal processing, and weather clutter removal processing as clutter removal processing. It obtains land / sea type information of the area where the target symbol is overlaid from the display unit 7, and selects ground clutter removal processing if the area is land, sea clutter removal processing if it is the sea, and weather clutter removal processing if the altitude is within the range affected by weather.

[0017] In the above configuration, the specific operation will be explained with reference to Figures 2 to 4.

[0018] Figure 2 shows an example of displaying a map including the radar device's own position, radar information, selected target information, and target list in an embodiment; Figure 3 shows the application areas and detection results of land / sea information and ground clutter / sea clutter removal processing in the range direction from the map information in an embodiment; and Figure 4 is a flowchart showing the processing flow of automatic switching control of area determination and clutter removal processing for received digital signals in an embodiment.

[0019] As an example, we will explain the function of automatically selecting the appropriate clutter removal process depending on the search area when the radar system's search area includes both land and sea. Here, we will use ground clutter and sea clutter as examples of clutter removal targets.

[0020] In the display unit 7, as shown in Fig. 2(a), the coastline is displayed based on map information such that land / sea areas around the installation position of the radar device can be identified, by matching the position of the radar device on the map with the self-position detected by the self-position detection unit 6. The signal processing unit 4 generates radar information including time, latitude and longitude as shown in Fig. 2(b), selected target information including number, azimuth, elevation angle, altitude, speed and time as shown in Fig. 2(c), and a target list which lists azimuth, elevation angle, altitude, speed and time for each number assigned to a target as shown in Fig. 2(d). The display unit 7 displays the position of each individual target on the map based on the radar information, the selected target information and the target list generated by the signal processing unit 4.

[0021] Fig. 3 shows an image of automatic selection of clutter removal according to land / sea areas. On the display unit 7, for the land / sea areas in the range direction with the own device as the starting point obtained from map information, the range of ground clutter removal processing and the range of sea clutter removal processing are set in range units, clutter removal processing is performed in each processing range, and target detection cells are extracted. Note that since the clutter removal processing is executed in fixed range units, a deviation occurs between the land / sea boundary defined by the coastline on the map and the boundary between the ground clutter removal processing range and the sea clutter removal processing range.

[0022] Here, in the above description of the embodiment, description is given taking land and sea as examples; however, it is also possible to flexibly set signal processing such as clutter removal processing, for example weather clutter removal processing, by utilizing altitude information (such as high altitude / low altitude) included in map information.

[0023] For example, as shown in Figure 4, the automatic clutter removal selection process takes in the received digital signal obtained by the receiving unit 3, the land / sea / area information obtained by the display unit 7, and the position and true north information of the radar device obtained by the self-position detection unit 6, and determines whether the received digital signal is in the land, sea, or air area (step S1). If it is determined to be land, the ground clutter removal process is selected to suppress the ground clutter signal (step S2), and the target detection process is executed (step S3). If it is determined to be sea, the sea clutter removal process is selected to suppress the sea clutter signal (step S4), and the target detection process is executed (step S5). If it is determined to be air, the weather clutter removal process is selected to suppress the weather clutter (step S6), and the target detection process is executed (step S7). Finally, the target detection results for land, sea, and air are displayed as target information (display information) on the display unit 7 (step S8).

[0024] In other words, the self-position detection unit 6 determines the radar device's own position and true north. The display unit 7 holds map information, and from this map information, the self-position, and true north information, it becomes possible to determine whether a given area is land, sea, or air based on the distance and direction from the radar device (self-position).

[0025] Since the digital signal received from the receiver 3 includes distance and direction information from its own position, clutter processing can be separated for each land, sea, and air area to suppress each clutter signal.

[0026] It should be noted that the present invention is not limited to the above embodiments, and the components can be modified and implemented in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiments. Moreover, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0027] 1...Antenna unit, 2...Transmitter unit, 3...Receiver unit, 4...Signal processing unit, 5...Control unit, 6...Self-position detection unit, 7...Display unit.

Claims

1. An antenna section that forms a search beam in the indicated direction, emits a transmitted RF signal, and receives the reflected signal, A transmitting unit that generates the aforementioned RF signal and outputs it to the antenna unit, A receiving unit that converts the signal received by the antenna unit into a baseband received digital signal, A signal processing unit performs clutter removal processing on the received digital signal, then performs target detection processing to generate target information including the azimuth, elevation, and distance of the detected target. A control unit generates a beam control signal indicating the initial direction of the search beam formation and outputs it to the antenna unit, then calculates the beam directional angle for the detected target based on the target information obtained by the signal processing unit, generates a beam control signal indicating the direction of the search beam formation based on this beam directional angle and outputs it to the antenna unit, and outputs a transmission control signal to the transmitter unit indicating the transmission schedule for the transmitted RF signal, A self-position detection unit that receives positioning signals from multiple satellites to detect its own position and generates true north information, A display unit that stores map information including its own position and at least distinguishes between land and sea areas, displays a map based on the map information and the self-position and true north information obtained by the self-position detection unit, and overlays target symbols indicating the detected target on the map based on the target information obtained by the signal processing unit. It is equipped with, The signal processing unit includes at least a ground clutter removal process and a sea clutter removal process as the clutter removal process, and acquires land / sea type information of the area where the target symbol is overlaid from the display unit, and selects and executes the ground clutter removal process if the area is land, and the sea clutter removal process if the area is sea. Radar device.

2. The display unit obtains altitude information of the detected target from the target information and displays the altitude near the target symbol, and outputs altitude classification information. The signal processing unit further calculates altitude from the azimuth angle, elevation angle, and distance and includes it in the target information, and provides altitude-specific weather clutter removal processing as clutter removal processing, and selectively executes the altitude-specific weather clutter removal processing based on the altitude classification information output from the display unit. The radar device according to claim 1.

3. It forms a search beam in the indicated direction and periodically emits a transmit RF signal according to the transmission schedule. The reflected signal of the transmitted RF signal is received, The received reflected signal is converted into a baseband received digital signal. After performing clutter removal processing on the received digital signal, target detection processing is performed to generate target information including the azimuth, elevation, and distance of the detected target. After specifying the initial formation direction for the search beam, the beam directionality angle relative to the detected target is calculated based on the target information, and the beam control is performed by specifying the formation direction of the search beam based on this beam directionality angle. It receives positioning signals from multiple satellites to detect its own position and generates true north information. The system stores map information that includes the user's own position and at least distinguishes between land and sea areas; displays a map based on the map information, the user's own position, and true north information; and overlays target symbols indicating the detected targets on the map based on the target information. Applied to radar equipment, The clutter removal process includes at least a ground clutter removal process and a sea clutter removal process, and acquires land / sea type information of the area where the target symbol is overlaid. If the land / sea type information of the area is land, the ground clutter removal process is selected and executed; if it is sea, the sea clutter removal process is selected and executed. A method for processing radar signals from a radar system.

4. The system obtains altitude information of the detected target from the target information and displays its altitude near the target symbol, and outputs altitude classification information. Furthermore, the clutter removal process includes altitude-specific weather clutter removal processing, and calculates the altitude from the azimuth angle, elevation angle, and distance of the detected target and includes it in the target information. Based on the aforementioned altitude classification information, the weather clutter removal process for each altitude is selectively executed. A method for processing radar signals in a radar device according to claim 3.

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