Radar device, echo image generating method and echo image generating program

Abstract

To generate an echo image indicating a more accurate detection result of a target.SOLUTION: A radar device includes: an acquisition unit that acquires echo data indicating a correspondence relation between a position in a detection target area and a level of a reflection wave obtained when an electromagnetic wave transmitted via an antenna is reflected at the position; a detection unit that detects a target on the basis of the echo data; a land determination unit that determines whether or not the target is a land on the basis of an area of the target; a harbor determination unit that determines whether or not a position of a ship is inside a harbor on the basis of a distance between the ship and the land; a threshold value decision unit that determines a threshold value for the level of the reflection wave according to a determination result of whether or not it is inside the harbor; and a generation unit that generates an echo image on the basis of the threshold value and the echo data.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a radar device, an echo image generating method, and an echo image generating program. [Background technology]

[0002] Conventionally, technologies for accurately detecting targets have been developed. For example, Patent Document 1 (JP 2009-103581 A) discloses the following automatic gain control device. That is, the automatic gain control device compares the amplitude of a received signal obtained from a radar search area with a predetermined threshold and outputs a received signal having an amplitude equal to or greater than the predetermined threshold, and includes: a determination unit that determines whether the ship's position is inside or outside the port area; a threshold calculation unit that calculates a first threshold to be used outside the port area or a second threshold to be used inside the port area based on the determination result of the determination unit; and an output control unit that controls the gain of the received signal using the threshold calculated by the threshold calculation unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-103581 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-26034 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-89056 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a need for a technology that goes beyond the technology described in Patent Document 1 and that is capable of generating an echo image that shows a more accurate detection result of a target.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a radar device, an echo image generation method, and an echo image generation program that are capable of generating echo images that show more accurate detection results of targets. [Means for solving the problem]

[0006] (1) The radar device of the present disclosure is a radar device mounted on a ship, and includes an acquisition unit that acquires echo data indicating the correspondence between a position in a detection area and the level of a reflected wave of electromagnetic waves transmitted via an antenna and reflected at the position; a detection unit that detects a target object based on the echo data; a land determination unit that determines whether the target object is land based on the area of ​​the target object; a harbor determination unit that determines whether the ship is located within a harbor based on the distance between the ship and the land; a threshold determination unit that determines a threshold for the level of the reflected wave depending on the determination result of whether the ship is located within the harbor; and a generation unit that generates an echo image in the detection area based on the threshold and the echo data.

[0007] In this way, by configuring the system to generate an echo image based on the echo data and a threshold determined depending on whether the ship is located within a port, it is possible to generate an echo image that shows the detection results of relatively small targets within the port while generating an echo image from which noise outside the port has been removed, thereby reducing false detection and missed detection of targets. Furthermore, by configuring the system to determine whether a target is land based on the area of ​​the target and to determine whether the ship is located within the port based on the distance between the ship and land, it is possible to more accurately determine whether the ship is located within the port based on its positional relationship with land in the detection area. Therefore, it is possible to generate an echo image that shows more accurate detection results of targets.

[0008] (2) In the above (1), the land determination unit may determine whether the target is land based on the width of the target in the azimuth direction and the width of the target in the distance direction.

[0009] This configuration makes it possible to prevent large targets, such as large ships, from being mistakenly detected as land, and to more accurately detect land in the detection area.

[0010] (3) In the above (1) or (2), the threshold value determination unit may perform an adjustment process to adjust the threshold value based on the density of noise echoes around the ship.

[0011] With this configuration, an echo image can be generated using a more appropriate threshold value for suppressing false detection and missed detection of a target.

[0012] (4) In the above (3), the threshold determination unit may adjust the threshold determined when it is determined in the adjustment process that the position of the ship is within the port.

[0013] With this configuration, it is possible to generate an echo image from which noise has been removed, for example, within a harbor.

[0014] (5) In (3) or (4) above, the threshold determination unit may adjust the threshold in the adjustment process based on the density of the noise echoes in an area within the distance from the ship between the ship and the land closest to the ship.

[0015] With this configuration, it is possible to generate an echo image from which noise such as sea surface reflections occurring near the ship has been removed.

[0016] (6) In any of (1) to (5) above, the port determination unit may determine whether the position of the ship is within the port based on the distance between the ship and the land closest to the ship.

[0017] This configuration reduces the processing load involved in determining whether the ship is located within a port or not.

[0018] (7) The echo image generation method disclosed herein is an echo image generation method for a radar device mounted on a ship, which acquires echo data indicating the correspondence between a position in a detection area and the level of a reflected wave of electromagnetic waves transmitted via an antenna and reflected at the position, detects a target based on the echo data, determines whether the target is land based on the area of ​​the target, determines whether the ship is located within a port based on the distance between the ship and the land, determines a threshold for the level of the reflected wave depending on the determination result of whether the ship is located within the port, and generates an echo image in the detection area based on the threshold and the echo data.

[0019] In this way, by using a method for generating an echo image based on echo data and a threshold determined depending on whether the ship is located within a port, it is possible to generate an echo image that shows the detection results of relatively small targets within the port while generating an echo image from which noise outside the port has been removed, thereby reducing false detection and missed detection of targets. Furthermore, by using a method for determining whether a target is land based on the area of ​​the target and determining whether the ship is located within a port based on the distance between the ship and land, it is possible to more accurately determine whether the ship is located within a port based on its positional relationship with land in the detection area. Therefore, it is possible to generate an echo image that shows more accurate detection results of targets.

[0020] (8) The echo image generation program of the present disclosure is an echo image generation program used in a radar device mounted on a ship, and is a program for causing a computer to execute the following processes: acquiring echo data indicating the correspondence between a position in a detection area and the level of a reflected wave of an electromagnetic wave transmitted via an antenna reflected at the position; detecting a target based on the echo data; determining whether the target is land based on the area of ​​the target; determining whether the ship is located within a port based on the distance between the ship and the land; determining a threshold for the level of the reflected wave depending on the determination result of whether the ship is located within the port; and generating an echo image in the detection area based on the threshold and the echo data.

[0021] In this way, by configuring the system to generate an echo image based on the echo data and a threshold determined depending on whether the ship is located within a port, it is possible to generate an echo image that shows the detection results of relatively small targets within the port while generating an echo image from which noise outside the port has been removed, thereby reducing false detection and missed detection of targets. Furthermore, by configuring the system to determine whether a target is land based on the area of ​​the target and to determine whether the ship is located within the port based on the distance between the ship and land, it is possible to more accurately determine whether the ship is located within the port based on its positional relationship with land in the detection area. Therefore, it is possible to generate an echo image that shows more accurate detection results of targets. [Effects of the Invention]

[0022] According to the present disclosure, an echo image can be generated that shows a more accurate detection result of a target. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a radar device according to an embodiment of the present disclosure. [Figure 2]FIG. 2 is a diagram illustrating a portion of detection data generated by a setting unit in a radar device according to an embodiment of the present disclosure. [Figure 3] FIG. 3 is a diagram for explaining the land determination process performed by the setting unit in the radar device according to the embodiment of the present disclosure. [Figure 4] FIG. 4 is a flowchart illustrating an example of an operation performed by the radar device according to the embodiment of the present disclosure when performing display processing. [Figure 5] FIG. 5 is a flowchart illustrating an example of an operation performed by the radar device according to the embodiment of the present disclosure when determining a display threshold value. [Figure 6] FIG. 6 is a flowchart illustrating an example of an operation performed by the radar device according to the embodiment of the present disclosure when performing an adjustment process. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and their description will not be repeated. Furthermore, at least some of the embodiments described below may be combined in any manner.

[0025] [Configuration and basic operation] FIG. 1 is a diagram illustrating a configuration of a radar device according to an embodiment of the present disclosure. Referring to FIG. 1, the radar device 101 includes an antenna 11, a transceiver 12, a signal processor 13, a setting unit 14, a display processor 15, and a memory 16. The signal processor 13 is an example of an acquisition unit. The setting unit 14 is an example of a detection unit, an example of a land determination unit, an example of a port determination unit, and an example of a threshold determination unit. The display processor is an example of a generation unit. Some or all of the functions of the transceiver 12, the signal processor 13, the setting unit 14, and the display processor 15 are realized, for example, by a processing circuit including one or more processors. The memory 16 is, for example, a non-volatile memory included in the processing circuit.

[0026] The radar device 101 is mounted on the ship 1. The radar device 101 performs display processing to display, on a display device (not shown), an echo image indicating the position of a target S, such as another ship, in a detection target area Ta. For example, the detection target area Ta is an area inside a circle of a predetermined size centered on the ship 1.

[0027] (Transmitter / Receiver) The transmitter / receiver 12 transmits electromagnetic waves and receives reflected waves at transmission / reception timings according to a predetermined sweep period Cy1. More specifically, during a sweep period T1 of a predetermined length starting from the transmission / reception timing, the transmitter / receiver 12 transmits electromagnetic waves to a division target area Da via the antenna 11 and receives reflected waves of the transmitted electromagnetic waves via the antenna 11. The division target area Da is a sector-shaped region obtained by dividing the detection target area Ta into N sections along the azimuth direction, where N is an integer greater than or equal to 2.

[0028] The transmitter / receiver 12 generates digital data Dd by digitally converting the echo signal representing the received reflected wave. The transmitter / receiver 12 repeatedly transmits the electromagnetic wave and generates the digital data Dd while rotating the antenna 11 so that the azimuth angle of the transmission direction of the electromagnetic wave changes by a predetermined angle for each sweep period Cy1. Each time the transmitter / receiver 12 generates digital data Dd, it outputs the generated digital data Dd to the signal processing unit 13. Hereinafter, the period in which the antenna 11 rotates once is also referred to as a scan period Cy2.

[0029] (Signal processing unit) The signal processing unit 13 generates echo data E that indicates the correspondence between a position in the detection area Ta and the level of a wave reflected at that position from an electromagnetic wave transmitted via the antenna 11.

[0030] For example, every time the signal processing unit 13 receives digital data Dd from the transceiver unit 12, it generates divided echo data Ed, which is echo data E indicating the correspondence between positions in the division target area Da and the echo levels at those positions, based on the received digital data Dd. The echo level at each position in the divided echo data Ed indicates the level of the reflected wave reflected at that position. Every time the signal processing unit 13 generates divided echo data Ed, it stores the generated divided echo data Ed in the storage unit 16.

[0031] (Settings section) (1) Target detection processing The setting unit 14 performs a target detection process to detect a target S based on the echo data E. For example, the setting unit 14 performs the target detection process at a set timing according to the scan cycle Cy2. More specifically, each time the number of divided echo data Ed stored in the storage unit 16 by the signal processing unit 13 reaches N, the setting unit 14 acquires the N pieces of divided echo data Ed from the storage unit 16. The setting unit 14 concatenates the acquired N pieces of divided echo data Ed to generate concatenated echo data Et, which is echo data E indicating the correspondence between positions in the detection target area Ta and the echo levels at those positions.

[0032] The setting unit 14 compares the echo level at each position in the generated connected echo data Et with a predetermined detection threshold V1. Then, the setting unit 14 converts the echo level values ​​at positions in the connected echo data Et where the echo level is equal to or greater than the detection threshold V1 to "1" and converts the echo level values ​​at positions where the echo level is less than the detection threshold V1 to "zero" to generate detection data EtB.

[0033] FIG. 2 is a diagram illustrating a portion of detection data generated by a setting unit in a radar device according to an embodiment of the present disclosure. FIG. 2 illustrates a plurality of cells C arranged in a matrix on two-dimensional coordinates corresponding to a detection target area Ta. For example, each cell C corresponds to a detection position of an echo level. Hatched cells C are cells C with an echo level value of "1." Unhatched cells C are cells C with an echo level value of "0." For example, one column of cells C on the two-dimensional coordinates corresponds to one division target area Da. Note that, in reality, the azimuth direction is a curved direction and the shape of the cells C is represented by a curve; however, in FIG. 2, for simplicity of explanation, the azimuth direction is represented as a straight line and the shape of the cells C is represented as a square.

[0034] 2, the setting unit 14 generates detection data EtB indicating a correspondence relationship between a plurality of cells C arranged in a matrix on two-dimensional coordinates corresponding to the detection target area Ta and the echo levels of the cells C. The setting unit 14 detects a target S in the detection target area Ta based on the generated detection data EtB. Hereinafter, a cell C with an echo level of "1" will also be referred to as "cell C1," and a cell C with an echo level of "zero" will also be referred to as "cell C0."

[0035] For example, the setting unit 14 calculates the echo size, which is the magnitude of the echo EC represented by the cell C1, and determines whether the echo EC is a target S or a noise echo Ns, depending on the calculated echo size.

[0036] More specifically, the setting unit 14 performs a continuity determination process to determine whether the cell C1 in the nth column and the cell C1 in the (n-1)th column are cells C1 corresponding to a common echo EC, based on the position of the cell C1 in the nth column and the position of the cell C1 in the (n-1)th column adjacent to the nth column in the direction opposite to the rotation direction of the antenna 11. Here, n is an integer equal to or greater than 1.

[0037] In the continuity determination process, the setting unit 14 detects, among one or more cells C1 that are consecutive in the distance direction in the nth column, a falling cell C1d in which the adjacent cell C in the transmission direction of the electromagnetic waves is cell C0, and a rising cell C1u in which the adjacent cell C in the direction opposite to the transmission direction of the electromagnetic waves is cell C0.

[0038] When the setting unit 14 detects a falling cell C1d and a rising cell C1u in the nth column, if the cell C1 in the (n-1)th column belongs to a row between the row of the falling cell C1d and the row of the rising cell C1u, it determines that the cell C1 between the falling cell C1d and the rising cell C1u in the nth column and the cell C1 in the (n-1)th column are cells C1 corresponding to a common echo EC.

[0039] On the other hand, if cell C1 in the (n-1)th column does not belong to a row between the row of the falling cell C1d and the row of the rising cell C1u, the setting unit 14 determines that cell C1 between the falling cell C1d and the rising cell C1u in the nth column and cell C1 in the (n-1)th column are cells C1 corresponding to different echoes EC.

[0040] The setting unit 14 detects the positions, number, and magnitude of echoes EC in the detection target area Ta by performing continuity determination processing for each column in the detection data EtB. Note that, instead of the above-described continuity determination processing, the setting unit 14 may detect the positions, number, and magnitude of echoes EC in the detection target area Ta according to the method described in Patent Document 2 (JP 2008-26034 A) or Patent Document 3 (JP 2014-89056 A).

[0041] The setting unit 14 calculates the number of cells C1 corresponding to the detected echo EC as the echo size of the echo EC. If the echo size of the echo EC is equal to or greater than a predetermined value, the setting unit 14 determines that the echo EC is a target S. On the other hand, if the echo size of the echo EC is less than the predetermined value, the setting unit 14 determines that the echo EC is a noise echo Ns.

[0042] (2) Land determination processing 3 is a diagram illustrating a land determination process performed by a setting unit in a radar device according to an embodiment of the present disclosure. Referring to FIG. 3, the setting unit 14 performs a land determination process to determine whether or not a target S is land L based on the area of ​​the target S, the width W1 of the target S in the azimuth direction, and the width W2 of the target S in the distance direction, at a set timing according to a scan period Cy2.

[0043] More specifically, when the setting unit 14 detects a target S, it calculates the number of cells Nc, which is the number of cells C1 corresponding to the target S, the width W1 of the target S in the azimuth direction, and the width W2 of the target S in the range direction. The number of cells Nc corresponds to the area of ​​the target S in a planar view. The setting unit 14 compares the calculated number of cells Nc and widths W1 and W2 with predetermined determination thresholds Tha, Thb, and Thc, respectively.

[0044] The setting unit 14 determines that the target S is land L if the number of cells Nc of the target S is greater than or equal to the judgment threshold Tha, the width W1 of the target S is greater than or equal to the judgment threshold Thb, and the width W2 of the target S is greater than or equal to the judgment threshold Thc.

[0045] On the other hand, if the number of cells Nc of the target S is less than the judgment threshold Tha, or the width W1 of the target S is less than the judgment threshold Thb, or the width W2 of the target S is less than the judgment threshold Thc, the setting unit 14 determines that the target S is not land L.

[0046] (3) Port Determination Processing The setting unit 14 performs a port determination process to determine whether the position of the ship 1 is within a port, at a set timing according to the scan cycle Cy2, based on the distance D between the ship 1 and land L. For example, the setting unit 14 determines whether the position of the ship 1 is within a port, based on the distance D between the ship 1 and land L closest to the ship 1.

[0047] More specifically, the setting unit 14 calculates the distance D between the vessel 1 and the land L that is closest to the vessel 1. Then, the setting unit 14 compares the calculated distance D with a predetermined determination threshold value Thd.

[0048] If the distance D is equal to or less than the determination threshold value Thd, the setting unit 14 determines that the position of the ship 1 is within the port.

[0049] On the other hand, if the distance D is greater than the determination threshold value Thd, the setting unit 14 determines that the position of the ship 1 is not within the port.

[0050] (4) Determining the display threshold Vd The setting unit 14 determines the display threshold value Vd for the level of the reflected wave in accordance with the determination result of whether or not the ship 1 is located within a harbor at a set timing according to the scan cycle Cy2.

[0051] More specifically, the storage unit 16 stores display thresholds Vd1 and Vd2, which are the display threshold Vd. The display threshold Vd1 is assumed to be smaller than the display threshold Vd2.

[0052] When the setting unit 14 determines that the position of the ship 1 is within a port, it determines the display threshold Vd to be used for generating the display data EtD as the display threshold Vd1. Then, the setting unit 14 outputs threshold information It1, which is threshold information It indicating that the display threshold Vd1 should be used, to the display processing unit 15.

[0053] On the other hand, if the setting unit 14 determines that the position of the ship 1 is not within a port, it determines the display threshold Vd for the level of the reflected wave as the display threshold Vd2. Then, the setting unit 14 outputs threshold information It2, which is threshold information It indicating that the display threshold Vd2 should be used, to the display processing unit 15.

[0054] (5) Adjustment process The setting unit 14 performs an adjustment process to adjust the display threshold Vd at a set timing according to the scan cycle Cy2, based on the density of noise echoes Ns around the ship 1. For example, in the adjustment process, the setting unit 14 adjusts the display threshold Vd1 determined when it is determined that the ship 1 is located within a harbor, based on the density of noise echoes Ns in an area whose distance from the ship 1 is within a distance D between the ship 1 and the land L closest to the ship 1.

[0055] More specifically, after outputting the threshold information It1 to the display processing unit 15, if the setting unit 14 determines that the position of the ship 1 is within a port in the port determination process at a newly set timing according to the scan cycle Cy2, the setting unit 14 calculates a noise echo number Cnt, which is the number of noise echoes Ns in a circular target area Ac centered on the ship 1 and having a radius equal to the length of the distance D. The setting unit 14 calculates a divisor Nd by dividing the calculated noise echo number Cnt by the area of ​​the target area Ac. The setting unit 14 then compares the calculated divisor Nd with predetermined adjustment thresholds M1 and M2. Here, the adjustment threshold M1 is assumed to be smaller than the adjustment threshold M2.

[0056] When the divisor Nd is equal to or greater than the adjustment threshold M2, the setting unit 14 outputs an adjustment instruction A1 to the display processing unit 15 to instruct the display processing unit 15 to add a predetermined adjustment value Vm1 to the display threshold Vd1.

[0057] On the other hand, when the divisor Nd is equal to or smaller than the adjustment threshold M1, the setting unit 14 outputs an adjustment instruction A2 to the display processing unit 15 to subtract a predetermined adjustment value Vm2 from the display threshold Vd1. The adjustment value Vm2 may be the same as or different from the adjustment value Vm1.

[0058] On the other hand, when the divisor Nd is greater than the adjustment threshold M1 and smaller than the adjustment threshold M2, the setting unit 14 does not output the adjustment instructions A1 and A2 to the display processing unit 15.

[0059] (Display processing unit) The display processing unit 15 generates an echo image of the detection target area Ta based on the display threshold Vd and the echo data E, and performs display processing to display the echo image on a display device (not shown).

[0060] More specifically, every time the signal processing unit 13 stores the divided echo data Ed in the storage unit 16, the display processing unit 15 acquires the divided echo data Ed from the storage unit 16. The display processing unit 15 performs a comparison process to compare the echo level at each position in the acquired divided echo data Ed with the display threshold value Vd indicated by the latest threshold value information It received from the setting unit 14.

[0061] Then, the display processing unit 15 generates display data EtD by converting the echo level values ​​at positions among the multiple positions in the divided echo data Ed where the echo level is equal to or greater than the display threshold Vd to "1", and converting the echo level values ​​at positions where the echo level is less than the display threshold Vd to "zero".

[0062] The display processing unit 15 generates a divided echo image, which is an echo image of the division target area Da, based on the generated display data EtD. More specifically, the display processing unit 15 generates a divided echo image that indicates that a target S is present at a position where the echo level is "1" and that a target S is not present at a position where the echo level is "zero." The display processing unit 15 performs display processing to display the generated divided echo image on a display device (not shown).

[0063] The display processing unit 15 generates and displays the divided echo images N times, thereby displaying an echo image consisting of N divided echo images. After displaying an echo image, the display processing unit 15 generates a new divided echo image for the division target area Da, and updates the divided echo image for the division target area Da displayed on the display device to the newly generated divided echo image.

[0064] For example, when the display processing unit 15 receives threshold information It1 indicating that the display threshold Vd1 should be used from the setting unit 14 and then receives an adjustment instruction A1 from the setting unit 14, the display processing unit 15 adds the adjustment value Vm1 to the display threshold Vd1. Then, the display processing unit 15 performs the above-described comparison process using the display threshold Vd1 to which the adjustment value Vm1 has been added.

[0065] Furthermore, for example, when the display processing unit 15 receives threshold information It1 indicating that the display threshold Vd1 should be used from the setting unit 14 and then receives an adjustment instruction A2 from the setting unit 14, the display processing unit 15 subtracts the adjustment value Vm2 from the display threshold Vd1. Then, the display processing unit 15 performs the above-described comparison process using the display threshold Vd1 from which the adjustment value Vm2 has been subtracted.

[0066] [Operation flow] A radar device according to an embodiment of the present disclosure includes a computer including a memory, and a processor such as a CPU in the computer reads from the memory and executes a program including some or all of the steps in the following flowchart. The program for this device can be installed externally. The program for this device is distributed in a state stored on a recording medium or via a communication line.

[0067] FIG. 4 is a flowchart illustrating an example of an operation performed by the radar device according to the embodiment of the present disclosure when performing display processing.

[0068] Referring to FIG. 4, the radar device 101 first waits for the transmission / reception timing according to the sweep period Cy1 (NO in step S11), and when the transmission / reception timing arrives (YES in step S11), it transmits electromagnetic waves to the division target area Da and receives reflected waves (step S12).

[0069] Next, the radar device 101 generates digital data Dd by digitally converting the echo signal indicating the received reflected wave, and generates divided echo data Ed based on the digital data Dd (step S13).

[0070] Next, the radar device 101 performs a comparison process to compare the echo level at each position in the divided echo data Ed with the display threshold Vd, and generates display data EtD by converting the echo level values ​​at positions where the echo level is equal to or greater than the display threshold Vd to "1" and converting the echo level values ​​at positions where the echo level is less than the display threshold Vd to "zero" (step S14).

[0071] Next, the radar device 101 generates a divided echo image of the division target area Da based on the generated display data EtD (step S15).

[0072] Next, the radar device 101 performs a display process to display the generated divided echo image on a display device (not shown) (step S16).

[0073] Next, the radar device 101 waits for a new transmission / reception timing (NO in step S11).

[0074] FIG. 5 is a flowchart illustrating an example of an operation performed by the radar device according to the embodiment of the present disclosure when determining a display threshold value.

[0075] Referring to FIG. 5, the radar device 101 first waits for a set timing according to the scan period Cy2 (NO in step S21), and when the set timing arrives (YES in step S21), generates concatenated echo data Et by concatenating N pieces of divided echo data Ed (step S22).

[0076] Next, the radar device 101 generates detection data EtB by converting the echo level values ​​at positions in the concatenated echo data Et where the echo level is equal to or greater than the detection threshold V1 to "1" and converting the echo level values ​​at positions where the echo level is less than the detection threshold V1 to "zero" (step S23).

[0077] Next, the radar device 101 detects the target S in the detection area Ta based on the detection data EtB (step S24).

[0078] Next, the radar device 101 performs a land determination process to determine whether the target S is land L based on the area of ​​the detected target S, the width W1 of the target S in the azimuth direction, and the width W2 of the target S in the distance direction (step S25).

[0079] Next, the radar device 101 performs a port determination process. More specifically, the radar device 101 compares the distance D between the ship 1 and the land L closest to the ship 1 with the determination threshold value Thd (step S26).

[0080] Next, if the distance D is equal to or less than the determination threshold value Thd (YES in step S27), the radar device 101 determines that the ship 1 is located within the harbor (step S28).

[0081] Next, the radar device 101 determines the display threshold Vd used to generate the display data EtD as the display threshold Vd1 (step S29), and waits for a new setting timing (NO in step S21).

[0082] On the other hand, if the distance D is greater than the determination threshold value Thd (NO in step S27), the radar device 101 determines that the ship 1 is not located within the harbor (step S30).

[0083] Next, the radar device 101 determines the display threshold Vd used to generate the display data EtD as the display threshold Vd2 (step S31), and waits for a new setting timing (NO in step S21).

[0084] Fig. 6 is a flowchart showing an example of an operation when the radar device according to the embodiment of the present disclosure performs an adjustment process. After determining that the position of the ship 1 is within a harbor in the port determination process (step S26) shown in Fig. 5, if the radar device 101 determines that the position of the ship 1 is within a harbor again in the port determination process (step S26) performed with the arrival of the next set timing, it executes the process shown in Fig. 6.

[0085] Referring to FIG. 6, first, the radar device 101 calculates the number of noise echoes Cnt, which is the number of noise echoes Ns in the target area Ac (step S41).

[0086] Next, the radar device 101 calculates a divisor Nd by dividing the number of noise echoes Cnt by the area of ​​the target area Ac (step S42).

[0087] Next, the radar device 101 compares the calculated divisor Nd with the adjustment thresholds M1 and M2 (step S43).

[0088] Next, if the divisor Nd is equal to or greater than the adjustment threshold M2 (YES in step S44), the radar device 101 adds the adjustment value Vm1 to the display threshold Vd1 used in the above-described comparison process (step S45), and ends the process.

[0089] On the other hand, if the divisor Nd is equal to or less than the adjustment threshold M1 (NO in step S44 and YES in step S46), the radar device 101 subtracts the adjustment value Vm2 from the display threshold Vd1 used in the above-mentioned comparison process (step S47) and terminates the process.

[0090] On the other hand, if the divisor Nd is greater than the adjustment threshold M1 and smaller than the adjustment threshold M2 (NO in step S44 and NO in step S46), the radar device 101 maintains the display threshold Vd1 and ends the process.

[0091] In the radar device 101 according to the embodiment of the present disclosure, the setting unit 14 is configured to perform land determination processing to determine whether or not the target S is land L based on the area of ​​the target S, the width W1 of the target S in the azimuth direction, and the width W2 of the target S in the distance direction, but this is not limited to this. The setting unit 14 may also be configured to perform land determination processing based on the area of ​​the target S without using the widths W1 and W2.

[0092] Furthermore, in the radar device 101 according to the embodiment of the present disclosure, the setting unit 14 is configured to perform the adjustment process, but this is not limiting. The setting unit 14 may be configured not to perform the adjustment process.

[0093] In addition, in the radar device 101 according to the embodiment of the present disclosure, the setting unit 14 is configured to perform target detection processing, land determination processing, harbor determination processing, and determination of the display threshold Vd at set timings according to the scan cycle Cy2, but this is not limited to this. For example, the setting unit 14 may be configured to perform target detection processing, etc., based on echo data E generated during a period M times the scan cycle Cy2, at set timings according to a cycle M times the scan cycle Cy2. Here, M is a positive number.

[0094] The above-described embodiments should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0095] 1 ship 11 Antenna 12 Transmitter / Receiver 13 Signal Processing Section 14 Setting section 15 Display processing section 16 Memory section 101 Radar equipment EtB detection data C0 cell C1d Falling cell C1u rising cell S target L Land Ac Target Area W1, W2 width D distance

Claims

1. A radar device mounted on a ship, an acquisition unit that acquires echo data indicating a correspondence relationship between a position in a detection target area and a level of a reflected wave of an electromagnetic wave transmitted via an antenna and reflected at the position; a detection unit that detects a target based on the echo data; a land determination unit that determines whether the target is land based on the area of ​​the target; a port determination unit that determines whether the location of the ship is within a port based on the distance between the ship and the land; a threshold determination unit that determines a threshold for the level of the reflected wave according to a determination result of whether the position of the ship is within the port; a generating unit that generates an echo image of the detection target area based on the threshold value and the echo data.

2. The radar device according to claim 1 , wherein the land determination unit determines whether the target is land based on a width of the target in an azimuth direction and a width of the target in a distance direction.

3. 3. The radar device according to claim 1, wherein the threshold value determining unit performs an adjustment process to adjust the threshold value based on a density of noise echoes around the ship.

4. The radar device according to claim 3 , wherein the threshold value determining unit adjusts the determined threshold value when the position of the ship is determined to be within the port in the adjustment process.

5. 4. The radar device according to claim 3, wherein the threshold determination unit adjusts the threshold in the adjustment process based on a density of the noise echoes in an area within a distance from the ship that is within a distance between the ship and the land that is closest to the ship.

6. 2. The radar device according to claim 1, wherein the port determination unit determines whether the ship is located within the port based on a distance between the ship and the land closest to the ship.

7. 1. A method for generating an echo image in a radar device mounted on a ship, comprising: Acquire echo data that indicates a correspondence relationship between a position in a detection target area and a level of a reflected wave that is an electromagnetic wave transmitted via an antenna and reflected at the position; Detecting a target based on the echo data; determining whether the target is land based on the area of ​​the target; determining whether the vessel is located within a port based on the distance between the vessel and the land; determining a threshold value for the level of the reflected wave according to a result of determining whether the position of the ship is within the port; an echo image generating method for generating an echo image of the detection target area based on the threshold value and the echo data;

8. An echo image generation program for use in a radar device mounted on a ship, comprising: A process of acquiring echo data indicating a correspondence relationship between a position in a detection target area and a level of a reflected wave of an electromagnetic wave transmitted via an antenna and reflected at the position; A process of detecting a target based on the echo data; a process of determining whether the target is land based on the area of ​​the target; a process of determining whether the vessel is located within a port based on the distance between the vessel and the land; A process of determining a threshold value for the level of the reflected wave according to a result of determining whether the position of the ship is within the port; an echo image generating program for causing a computer to execute a process of generating an echo image of the detection target area based on the threshold value and the echo data;

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