JP7273653B2 - Radar device and signal processing method - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to a radar device and a signal processing method.

A radar device that classifies targets such as ships using images acquired by an inverse synthetic aperture radar (ISAR) is known. Such radar equipment extracts target features from acquired ISAR images, and classifies targets by comparing them with the features of ships and the like that are stored in a database in advance.

Target features include, for example, the overall shape of the ship, various structures installed on the ship and their installation positions. In the process of extracting these features from the ISAR image, both ends of the target, that is, the bow and stern, are detected from the image, and the overall image of the target is specified. Identify in the image. Also, when classifying ships, it is important to accurately measure the length overall (LOA) of the ship.

An ISAR image is generated by synthesizing the echo signals reflected by the target. For this reason, depending on the propagation state of the radar signal, it is not always possible to obtain a clear image of the entire ship, and the bow or stern may appear in an unclear image with only low luminance. For example, the shadow of the mast may be superimposed on the bow or stern, and part of the image may be very dark and sufficient visibility may not be ensured.

Takashi Yoshida, "Revised Radar Technology", The Institute of Electronics, Information and Communication Engineers, October 1, 1996 (first edition), pp. 280 - 285

A problem to be solved by the present invention is to provide a radar apparatus and a signal processing method capable of more accurately measuring the total length of a target.

A radar apparatus according to an embodiment includes a generation unit that generates an ISAR image using an echo signal, a display unit that displays the ISAR image, and a display unit that displays first and second measurement lines according to a user's instruction. a first display processing unit displayed in the unit, and adjustment to make the brightness of a second region other than the first region higher than the brightness of the first region sandwiched between the first and second measurement lines in the ISAR image a second display processing unit that updates the positions of the first and second measurement lines according to user instructions; and a length measurement unit that measures the length based on the distance between the first and second measurement lines. and a measuring unit.

FIG. 1 is a block diagram showing the configuration of a radar device according to this embodiment. FIG. 2 is a block diagram showing the configuration of the image processing section shown in FIG. FIG. 3 is a flowchart for explaining the operation of the radar device according to this embodiment. FIG. 4 is an example of an ISAR image displayed on the display unit. FIG. 5 is an example of two measurement lines displayed on the display. FIG. 6 is an example of an image whose luminance has been adjusted. FIG. 7 is an example of an image with changed measurement lines.

Hereinafter, embodiments will be described with reference to the drawings. In the following description, elements having the same functions and configurations are denoted by the same reference numerals, and redundant description will be given only when necessary.

[1] Configuration of Radar Device FIG. 1 is a block diagram showing the configuration of a radar device 10 according to this embodiment. In this embodiment, a ship will be described as an example of a target to which radar signals are transmitted. The radar device 10 includes an antenna 11 , a circulator 12 , a transmitter 13 , a receiver 14 and a signal processor 15 .

Antenna 11 is attached to the exterior of a mobile body on which radar device 10 is mounted, and transmits and receives radio waves. Antenna 11 is, for example, a phased array antenna having a plurality of antenna elements arranged in an array.

The transmission unit 13 generates a transmission signal at a predetermined transmission cycle, and transmits the generated transmission signal from the antenna 11 via the circulator 12 toward the target vessel. A part of the transmitted signal transmitted from the antenna 11 is reflected by the target, and this reflected echo signal is received by the antenna 11 as a received signal.

The circulator 12 switches the paths of the transmission signal and the reception signal. The circulator 12 transmits a transmission signal from the transmission section 13 to the antenna 11 and transmits a reception signal received by the antenna 11 to the reception section 14 .

The receiving unit 14 determines the reception signal received by the antenna 11 based on the transmission cycle of the transmission signal. Also, the receiving unit 14 performs reception processing such as low-noise amplification, frequency conversion, and filtering on the received signal.

The signal processing device 15 acquires the received signal from the receiver 14 . The signal processor 15 processes the received signal. The functions of the signal processing device 15 are realized by arithmetic processing by a processor such as a CPU (Central Processing Unit). The signal processing device 15 includes an ISAR image generation unit 16 , an image processing unit 17 , a storage unit 18 , an input unit 19 and a display unit 20 .

The ISAR image generator 16 acquires the received signal from the receiver 14 . The ISAR image generator 16 performs aperture synthesis processing on a plurality of received signals to generate an ISAR image. Also, the ISAR image generator 16 can equivalently enlarge the aperture of the antenna 11 based on the relative motion between the antenna 11 and the target to improve the resolution.

The image processor 17 acquires the ISAR image from the ISAR image generator 16 . The image processing unit 17 executes image processing on the ISAR image. The image processing unit 17 also measures the total length of the ship (LOA: length overall). A specific configuration of the image processing unit 17 will be described later.

The storage unit 18 stores programs, various data, various parameters, and the like for realizing the functions of the image processing unit 17 . The storage unit 18 includes volatile memory and nonvolatile memory.

The input unit 19 receives instructions from the user. Information input to the input unit 19 is transmitted to the image processing unit 17 . The input unit 19 includes a touch panel and/or a trackball.

The display unit 20 displays the image transmitted from the image processing unit 17 on the screen. The display unit 20 is configured by an LCD (Liquid Crystal Display), an organic EL (electroluminescence) display, or the like.

The configuration of the image processing unit 17 will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the image processing section 17 shown in FIG. The image processing section 17 includes a display processing section 21 , a brightness adjustment section 22 , an LOA measurement section 23 and a data output section 24 .

The display processing unit 21 executes processing for displaying an image on the display unit 20 . Specifically, the display processing unit 21 displays the ISAR image generated by the ISAR image generation unit 16 on the display unit 20 . Also, the display processing unit 21 displays two measurement lines for measuring the LOA on the display unit 20 based on the information input by the user to the input unit 19 .

The brightness adjustment section 22 determines the area outside the two measurement lines in the image displayed on the display section 20 . In addition, the luminance adjustment section 22 adjusts the luminance of the area outside the two measurement lines.

The LOA measurement unit 23 calculates the distance between the two measurement lines and measures the LOA. The data output unit 24 outputs the measured LOA by a predetermined method.

[2] Operation The operation of the radar device 10 configured as described above will be described with reference to FIG. FIG. 3 is a flowchart for explaining the operation of the radar device 10. As shown in FIG.

The ISAR image generation unit 16 uses the reception signal received by the reception unit 14 to perform synthetic aperture processing to generate an ISAR image (step S100). The ISAR image generated by the ISAR image generator 16 is transmitted to the image processor 17 .

Subsequently, the display processing unit 21 displays the ISAR image on the display unit 20 (step S101). The initial brightness of the ISAR image can be arbitrarily set by the user, and is set so that the entire image of the vessel included in the ISAR image can be more easily visually recognized. FIG. 4 is an example of an ISAR image 30 displayed on the display unit 20. As shown in FIG. A ship 31 is displayed on the display unit 20 . In the example of FIG. 4, the shadow of the mast of the ship 31 overlaps the stern, making the stern very dark. Therefore, the shape of the stern cannot be visually recognized. In FIG. 4, the stern is indicated by a dashed line.

The user visually recognizes the ship displayed on the display unit 20 . Then, the user measures the LOA of the ship displayed on the display unit 20 . Specifically, it is assumed that the user operates the input unit 19 to place two measurement lines on each of the bow and stern of the ship.

Subsequently, the image processing unit 17 monitors whether information on the measurement line is input to the input unit 19 (step S102).

When the information on the measurement lines is input in step S102, the display processing unit 21 displays two measurement lines at the positions indicated by the user on the display unit 20 (step S103). FIG. 5 is an example of two measurement lines 32-1 and 32-2 displayed on the display unit 20. FIG. Since the bow can be visually recognized, the measurement line 32-1 is aligned with the bow. On the other hand, since the stern is not visible, the measurement line 32-2 is not aligned with the stern.

Subsequently, the brightness adjustment unit 22 determines the area outside the two measurement lines (step S104). In FIG. 5, areas outside the measurement lines 32-1, 32-2 are indicated by areas 33-1, 33-2. Areas 33-1 and 33-2 are areas of the ISAR image 30 other than the area between the measurement lines 32-1 and 32-2.

Subsequently, the brightness adjuster 22 makes the brightness of the area outside the two measurement lines higher than the brightness of the area inside the two measurement lines (step S105). The brightness is the brightness of the image displayed on the screen of the display unit 20 . FIG. 6 is an example of an image whose luminance has been adjusted. By increasing the brightness of the regions 33-1 and 33-2, the stern can be visually recognized. In step S105, in addition to increasing the brightness of the area outside the two measurement lines, the brightness of the area inside the two measurement lines may be decreased.

Subsequently, the image processing unit 17 monitors whether information on the measurement line has been input to the input unit 19 (step S106).

In step S106, the user changes the position of the measurement line if, for example, the stern can be visually recognized. When the information on the measurement lines is input in step S106, the display processing unit 21 updates the positions (display positions) of the two measurement lines (step S107). FIG. 7 is an example of an image with changed measurement lines. Since the user can visually recognize the stern in the area 33-2, the user changes the measurement line 32-2 to the position of the stern.

Subsequently, the LOA measurement unit 23 calculates the distance between the two measurement lines and measures the LOA (step S108).

On the other hand, if the measurement line information is not input in step S106, the process proceeds to step S108. Specifically, the LOA measurement unit 23 starts the process when the measurement line is not updated even after a predetermined period of time has passed from step S105.

Subsequently, the data output unit 24 outputs the measured LOA in a state that can be confirmed by the user (step S109). As an output method in step S109, the data output unit 24 displays the measured LOA on the display unit 20, for example.

[3] Effect of the Embodiment As described in detail above, in the present embodiment, the display processing unit 21 causes the display unit 20 on which the ISAR image is displayed to display two lines for measuring the LOA in accordance with the user's instruction. display the measurement line of The brightness adjustment unit 22 determines the area outside the two measurement lines in the ISAR image and increases the brightness of this area. The display processing unit 21 updates the positions of the two measurement lines according to the user's instruction. Then, the LOA measurement unit 23 calculates the distance between the two measurement lines to measure the total length (LOA) of the ship.

Therefore, according to this embodiment, the visibility can be improved in the area outside the two measurement lines. This allows the user to place exactly two lines of measurement in the ISAR image, one fore and one fore. As a result, it is possible to measure the LOA more accurately.

The radar device 10 according to the above embodiment is preferably mounted on an aircraft. Alternatively, the radar device 10 may be arranged on the ground.

In the above embodiment, a ship is taken as an example of a radar target, and an ISAR image of the ship is acquired. However, it is not limited to this, and it is also possible to set a moving object other than a ship as a target.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 10... Radar apparatus 11... Antenna 12... Circulator 13... Transmission part 14... Reception part 15... Signal processing apparatus 16... ISAR image generation part 17... Image processing part 18... Storage part 19... Input Unit 20 Display unit 21 Display processing unit 22 Brightness adjustment unit 23 LOA measurement unit 24 Data output unit 30 ISAR image 31 Ship 32-1, 32-2 Measurement line .

Claims (7)

A generator that generates an ISAR (Inverse Synthetic Aperture Radar) image using the echo signal;
a display unit that displays the ISAR image;
a first display processing unit that displays first and second measurement lines on the display unit in accordance with a user's instruction;
an adjustment unit that makes the brightness of a second region other than the first region higher than the brightness of the first region sandwiched between the first and second measurement lines in the ISAR image;
a second display processing unit that updates the positions of the first and second measurement lines in accordance with a user's instruction;
a measuring unit that measures the length based on the distance between the first and second measurement lines;
A radar device comprising The radar device according to claim 1, wherein the adjustment section determines the first area and the second area based on the first and second measurement lines. further comprising an input unit that receives information entered by the user;
The radar device according to claim 1 or 2, wherein the first and second display processing units execute processing based on information from the input unit. The radar device according to any one of claims 1 to 3, further comprising an output unit that outputs the measured length. The radar apparatus according to any one of claims 1 to 4, further comprising an antenna that transmits a transmission signal toward the target and receives the echo signal. The radar device according to claim 5, wherein the antenna is a phased array antenna. using the echo signals to generate an ISAR image;
displaying the ISAR image on the display unit;
displaying the first and second measurement lines on the display unit according to a user's instruction;
making the brightness of a second region other than the first region higher than the brightness of the first region sandwiched between the first and second measurement lines in the ISAR image;
updating the positions of the first and second measurement lines according to user instructions;
A signal processing method for measuring length based on the distance between the first and second measurement lines.

Images