Method and apparatus for detecting target using pulse radar

Abstract

A target detection method using a pulse radar according to the present invention comprises: a step of, in advance, transmitting a transmission pulse while moving near land to collect land clutter signals received after the transmission pulse is reflected from land, and constructing a land clutter database by storing land clutter signals, location information, and transmission direction information at each point where the land clutter signals are collected; a step of transmitting a transmission pulse to receive a signal reflected from a target and land for target detection; a step of obtaining land clutter signals from at least two points near the location where the received signal is received from the land clutter database; a step of estimating a land clutter signal included in the received signal using the land clutter signals from the at least two points; a step of removing the estimated land clutter signal from the received signal; and a step of detecting a target using the received signal from which the estimated land clutter signal has been removed.

Description

Technology Field

[0001] The present invention relates to a target detection method and apparatus using pulse radar. Background Technology

[0002] A pulse radar system is a system that utilizes pulse signals for radar transmission and reception. It transmits short pulses at each pulse repetition interval and detects targets by receiving reflected signals from targets during the time between pulses.

[0003] Pulse radar systems installed on warships generally transmit and receive pulses relative to the sea level. However, when conducting operations in coastal areas, it frequently occurs that signals reflected from land (including islands) are received in addition to signals reflected from targets. Since these received signals are captured along with the signals reflected from targets, they adversely affect the signal-to-noise ratio (SNR) of the target signal during signal processing, thereby resulting in a decrease in target detection accuracy.

[0004] Figure 1 is a diagram illustrating this situation. Referring to Figure 1, for a transmission pulse transmitted from the ship's radar, a target reflection signal reflected from a target and a land clutter signal reflected from the land are received. In this way, the signal reflected from the land becomes a clutter signal for a ship radar used to detect anti-ship targets. This is because there cannot be ship targets on land, and even if there are, they are ships that are anchored.

[0005] These land clutter signals lower the signal-to-noise ratio (SNR) of the target, making it difficult to detect the target, or cause the clutter to be detected as the target instead of the actual target, resulting in the failure to detect the target or the loss of the target. The problem to be solved

[0006] The technical problem to be solved by the present invention is to provide a target detection method and apparatus using a pulse radar that can improve target detection capability by collecting land clutter signals in advance and storing them in a database, and by using this to remove land clutter signals from a received signal containing land clutter signals during target detection.

[0007] The problems to be solved by the present invention are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0008] A target detection method using a pulse radar according to the present invention for solving the above technical problem comprises: a step of, in advance, transmitting a transmission pulse while moving near land to collect land clutter signals received after the transmission pulse is reflected from land, and constructing a land clutter database by storing land clutter signals, location information, and transmission direction information at each point where the land clutter signals are collected; a step of transmitting a transmission pulse to receive a signal reflected from a target and land for target detection; a step of obtaining land clutter signals from at least two points near the location where the received signal is received from the land clutter database; a step of estimating a land clutter signal included in the received signal using the land clutter signals from the at least two points; a step of removing the estimated land clutter signal from the received signal; and a step of detecting a target using the received signal from which the estimated land clutter signal has been removed.

[0009] The above-mentioned estimation step can estimate the land clutter signal included in the received signal by interpolating the land clutter signals of the at least two points based on the location where the received signal was received.

[0010] The above acquisition step can acquire land clutter signals at at least two points where the transmission direction is the same as the transmission direction for the received signal.

[0011] The above-mentioned estimation step can interpolate the land clutter signals of the at least two points based on the distance from each of the at least two points to the land in the corresponding transmission direction and the distance from the location where the received signal was received to the land in the corresponding transmission direction.

[0012] The above-mentioned estimation step may convert a land clutter signal at one of the at least two points into a land clutter signal at the location where the received signal is received, based on the distance to the land in the transmission direction and the distance from the location where the received signal is received to the land in the transmission direction; convert a land clutter signal at the other of the at least two points into a land clutter signal at the location where the received signal is received, based on the distance to the land in the transmission direction and the distance from the location where the received signal is received to the land in the transmission direction; and estimate the land clutter signal included in the received signal by averaging the converted land clutter signal of the one point and the converted land clutter signal of the other point.

[0013] In the above-mentioned estimation step, converting the received signal into a land clutter signal at the location where it was received can convert the signal strength and temporal location based on the distance to the land.

[0014] Converting signal strength and temporal location based on the distance to the land mentioned above can be done by utilizing the fact that signal strength is inversely proportional to the fourth power of the distance and time delay is proportional to the distance.

[0015] A target detection device using a pulse radar according to the present invention for solving the above technical problem comprises: a clutter database construction unit that, in advance, collects land clutter signals received by reflection from land of a transmission pulse transmitted while moving near land, and stores land clutter signals, location information, and transmission direction information at each point where the land clutter signals are collected to construct a land clutter database; a storage unit that stores the land clutter database; a pulse transmission / reception unit that transmits a transmission pulse for target detection and receives a reception signal reflected from a target and land by the transmission pulse; a land clutter removal unit that obtains land clutter signals from at least two points near the location where the reception signal is received from the land clutter database, estimates a land clutter signal included in the reception signal using the land clutter signals from the at least two points, and removes the estimated land clutter signal from the reception signal; and a target detection unit that detects a target using the reception signal from which the estimated land clutter signal has been removed.

[0016] The above land clutter removal unit can estimate the land clutter signal included in the received signal by interpolating the land clutter signals of the at least two points based on the location where the received signal was received.

[0017] The above land clutter removal unit can acquire land clutter signals at at least two points, the transmission direction of which is the same as the transmission direction for the received signal.

[0018] The above land clutter removal unit can interpolate the land clutter signals of the at least two points based on the distance from each of the at least two points to the land in the corresponding transmission direction and the distance from the location where the received signal was received to the land in the corresponding transmission direction.

[0019] The above land clutter removal unit converts a land clutter signal at one of the at least two points into a land clutter signal at the location where the received signal is received, based on the distance to the land in the transmission direction and the distance from the location where the received signal is received to the land in the transmission direction; converts a land clutter signal at the other of the at least two points into a land clutter signal at the location where the received signal is received, based on the distance to the land in the transmission direction and the distance from the location where the received signal is received to the land in the transmission direction; and estimates the land clutter signal included in the received signal by averaging the converted land clutter signal at the one point and the converted land clutter signal at the other point.

[0020] In the above-mentioned land clutter removal unit, converting the received signal into a land clutter signal at the location where it was received can convert the signal strength and temporal location based on the distance to the land.

[0021] Converting signal strength and temporal location based on the distance to the land mentioned above can be done by utilizing the fact that signal strength is inversely proportional to the fourth power of the distance and time delay is proportional to the distance. Effects of the invention

[0022] According to the present invention described above, land clutter signals are collected in advance and stored in a database, and by using this, land clutter signals are removed from a received signal containing land clutter signals during target detection, thereby improving target detection capability.

[0023] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0024] Figure 1 is a diagram illustrating a situation in which target reflection signals and land clutter signals are received together during coastal operations. FIG. 2 shows a block diagram of a target detection device using pulse radar according to one embodiment of the present invention. Figure 3 is a diagram illustrating the collection of land clutter signals by transmitting transmission pulses while moving near land. Figure 4 shows an example of transmitting a transmission pulse for target detection and receiving a reception signal reflected from the target and land. Figure 5 shows an example of acquiring land clutter signals at two points near the location where the received signal was received. Figure 6 shows an example of estimating land clutter signals included in a received signal using land clutter signals from two points. Figure 7 shows an example of obtaining a target reflection signal by removing the land clutter signal estimated from the received signal. FIGS. 8 and 9 are flowcharts of a target detection method using pulse radar according to an embodiment of the present invention. Specific details for implementing the invention

[0025] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In the following description and the attached drawings, substantially identical components are denoted by the same reference numerals to avoid redundant description. Furthermore, in describing the present invention, if it is determined that a detailed description of related known functions or configurations could unnecessarily obscure the essence of the invention, such detailed description will be omitted.

[0026] FIG. 2 shows a block diagram of a target detection device using pulse radar according to one embodiment of the present invention.

[0027] The target detection device according to the present embodiment may include a pulse transmitting / receiving unit (110), a pulse compression unit (120), a Doppler filtering unit (130), a target detection unit (140), a target display unit (150), a location and terrain information acquisition unit (160), a clutter database construction unit (170), a storage unit (180), and a land clutter removal unit (190). Depending on the embodiment, some blocks of the target detection device may be added, changed, or deleted.

[0028] The pulse transceiver (110) transmits a transmission pulse with a pulse repetition period and receives a reception signal including a target reflection signal reflected from a target for each transmission pulse.

[0029] The pulse compression unit (120) performs pulse compression processing on the received signal. Pulse compression processing is a process that amplifies the strength of the received signal and improves distance resolution.

[0030] The Doppler filtering unit (130) performs Doppler filtering on the pulse-compressed received signal.

[0031] The target detection unit (140) detects targets by applying a CFAR (Constant False Alarm Rate) threshold to the received signal.

[0032] The target display unit (150) displays targets through a display according to the target detection results.

[0033] The location and terrain information acquisition unit (160) acquires location and surrounding terrain information using a global positioning system (GPS). The surrounding terrain information can be acquired using the current location acquired via GPS and pre-stored map (nautical chart) information. According to an embodiment, the map information may be provided from the outside via a wireless communication network. From the location and terrain information, the distance to land in each direction from each location on the sea can be calculated.

[0034] The clutter database construction unit (170) transmits a transmission pulse through the pulse transmission and reception unit (110) while moving near the land (e.g., within tens to hundreds of km from the land) in advance, and collects land clutter signals received from the land where the transmission pulse is reflected. Then, the clutter database construction unit (170) constructs a land clutter database by storing the corresponding land clutter signal, location information, and transmission direction information of the transmission pulse at each point where the land clutter signal is collected. At this time, the transmission and reception of pulses can be performed in all directions using a rotating or three-dimensional active phased array radar. Therefore, land clutter signals can be collected and stored for each transmission direction at each point. The collected land clutter signals can be pulse compressed through the pulse compression unit (120) and Doppler filtered by the Doppler filtering unit (130) and stored.

[0035] The land clutter database constructed through the clutter database construction unit (170) is stored in the storage unit (180). The land clutter database stored in the storage unit (180) can be continuously updated through an additional land clutter signal collection process.

[0036] FIG. 3 is a diagram illustrating the collection of land clutter signals by transmitting transmission pulses while moving near land. As illustrated, land clutter signals are collected by transmitting transmission pulses and receiving reception signals while moving a radar-equipped platform (e.g., a ship) near land. At this time, location information (latitude, longitude data) and transmission direction information identified through the location and terrain information acquisition unit (160) are collected together. FIG. 3 shows an example of land clutter signals collected for a specific location and a specific transmission direction.

[0037] Referring again to FIG. 2, the land clutter removal unit (190) determines whether the received signal received through the pulse transceiver (110) contains a land clutter signal when a target is detected. For example, considering the maximum detection range of the radar, if the distance from the current location to the land is within a predetermined distance, it can be determined that the received signal contains a land clutter signal.

[0038] If it is determined that the received signal does not contain land clutter signals (e.g., when the distance from the current location to the land is greater than a predetermined distance), the land clutter removal unit (190) does not perform the land clutter signal removal operation described later, and the received signal, which has been Doppler filtered through the Doppler filtering unit (130), is input directly to the target detection unit (140), and the target detection unit (140) performs the target detection operation.

[0039] If it is determined that the received signal contains land clutter signals (e.g., when the distance from the current location to the land is within a predetermined distance), the land clutter removal unit (190) estimates the land clutter signals at the current location using the land clutter database stored in the storage unit (180) and performs the operation of removing the land clutter signals from the received signal.

[0040] FIG. 4 illustrates an example in which a pulse transceiver (110) transmits a transmission pulse from a current location (P) for target detection, and the transmission pulse receives a reception signal reflected from the target and the land. As illustrated, the reception signal includes a target reflection signal reflected from the target as well as a land clutter signal reflected from the land.

[0041] The land clutter removal unit (190) receives a received signal that has been pulse-compressed through the pulse compression unit (120) and Doppler-filtered through the Doppler filtering unit (130).

[0042] The land clutter removal unit (190) obtains land clutter signals from at least two points near the current location where the received signal was received from the land clutter database. Specifically, the land clutter removal unit (190) may obtain land clutter signals collected from points on the extension line of the transmission direction for the received signal (or within a certain distance therefrom), wherein the transmission direction is the same as the transmission direction for the received signal, and at least two points of land clutter signals. For convenience, the following description uses the example of obtaining land clutter signals from two points, but it is obvious that the same operation as described below can be performed by obtaining land clutter signals from three or more points.

[0043] Figure 5 illustrates an example of acquiring land clutter signals at two points near the location where the received signal was received. Referring to Figure 5, land clutter signals collected for the same direction as the pulse transmission direction at points ① and ②, respectively, on the extension line of the pulse transmission direction relative to the current location (P), are acquired from the land clutter database. Referring to Figures 4 and 5 together, due to the difference in distance to land, the land clutter signal at point ① has a lower signal strength than the land clutter signal at the current location (P), and the land clutter signal at point ② has a higher signal strength than the land clutter signal at the current location (P). Additionally, due to the difference in distance to land, the temporal position between pulses is such that the land clutter signal at point ① appears after the land clutter signal at the current location (P), and the land clutter signal at point ② appears before the land clutter signal at the current location (P).

[0044] The land clutter removal unit (190) estimates the land clutter signal included in the received signal using the land clutter signals from two acquired points. At this time, the land clutter removal unit (190) can estimate the land clutter signal included in the received signal by interpolating the land clutter signals from the two points based on the current location where the received signal was received. Specifically, the land clutter removal unit (190) can interpolate the land clutter signals from the two points based on the distance from each of the two points to the land in the corresponding transmission direction and the distance from the current location where the received signal was received to the land in the corresponding transmission direction.

[0045] For example, the land clutter removal unit (190) can convert the land clutter signal at point ① into a land clutter signal at the current location (P) based on the distance from point ① to the land in the corresponding transmission direction and the distance from the current location (P) to the land in the corresponding transmission direction. Additionally, the land clutter removal unit (190) can convert the land clutter signal at point ② into a land clutter signal at the current location (P) based on the distance from point ② to the land in the corresponding transmission direction and the distance from the current location (P) to the land in the corresponding transmission direction. The conversion to the land clutter signal at the current location (P) can convert the signal strength of the land clutter signal and the temporal position between pulses based on the distance to the land by utilizing the principle that signal strength is inversely proportional to the fourth power of the distance and time delay is proportional to the distance. And the land clutter removal unit (190) can estimate the land clutter signal included in the received signal by averaging the land clutter signal of the current location (P) converted from the land clutter signal of point ① and the land clutter signal of the current location (P) converted from the land clutter signal of point ②.

[0046] Figure 6 illustrates an example of estimating a land clutter signal included in a received signal using land clutter signals from two points. Figure 6 shows a land clutter signal (c) interpolated from a land clutter signal (a) at point ① and a land clutter signal (b) at point ②. Referring to Figure 6 (c), the interpolated land clutter signal has a greater signal strength and appears earlier in time than the land clutter signal at point ①, and has a smaller signal strength and appears later in time than the land clutter signal at point ②.

[0047] The land clutter removal unit (190) removes the land clutter signal estimated as above from the received signal. The removal of the land clutter signal can be performed by a simple subtraction operation of the land clutter signal estimated from the received signal.

[0048] FIG. 7 illustrates an example of obtaining a target reflection signal by removing the land clutter signal estimated from the received signal. As shown, by subtracting the land clutter signal (b), estimated through the interpolation of the land clutter signal at point ① and the land clutter signal at point ②, from the received signal (a) received at the current location (P), a target reflection signal (c) with the land clutter signal removed can be obtained.

[0049] Then, the target detection unit (140) detects a target using a received signal from which the estimated land clutter signal has been removed, and the target display unit (150) displays the target through a display according to the target detection result.

[0050] FIGS. 8 and 9 are flowcharts of a target detection method using a pulse radar according to an embodiment of the present invention. FIG. 8 is a flowchart illustrating the process of constructing a land clutter database in advance, and FIG. 9 is a flowchart illustrating the process of removing land clutter signals and detecting a target using the land clutter database. The target detection method using a pulse radar according to the present embodiment consists of steps processed in the target detection device using the pulse radar described above. Therefore, even if details are omitted below, the content described above applies to the target detection method using a pulse radar according to the present embodiment.

[0051] Referring to Fig. 8, in step 810, a transmission pulse is transmitted while moving near land, and the land clutter signal received from the transmission pulse reflected from land is collected.

[0052] In step 820, pulse compression processing is performed on the land clutter signal.

[0053] In step 830, Doppler filtering is performed on the pulse-compressed land clutter signal.

[0054] In step 840, a land clutter database is constructed by storing the land clutter signal, location information, and transmission direction information at each point where the land clutter signal is collected.

[0055] Referring to Fig. 9, for target detection, in step 910, a transmission pulse is transmitted and the transmission pulse is received from the target and the ground.

[0056] In step 920, pulse compression processing is performed on the received signal.

[0057] In step 930, Doppler filtering is performed on the pulse-compressed received signal.

[0058] In step 940, it is determined whether the received signal contains land clutter signals. For example, considering the maximum detection range of the radar, if the distance from the current location to the land is within a predetermined distance, it can be determined that the received signal contains land clutter signals.

[0059] If it is determined that the received signal does not contain land clutter (e.g., if the distance from the current location to the land is greater than a predetermined distance), proceed directly to step 980 and apply a CFAR (Constant False Alarm Rate) threshold to the received signal to detect the target.

[0060] If it is determined that the received signal contains land clutter signals (e.g., if the distance from the current location to the land is within a predetermined distance), in step 950, land clutter signals at least two points near the location where the received signal was received are obtained from the land clutter database.

[0061] In step 950, land clutter signals collected at points on the extension of the transmission direction for the received signal (or within a certain distance therefrom) can be obtained, and at least two land clutter signals at points where the transmission direction is the same as the transmission direction for the received signal.

[0062] Next, in step 960, land clutter signals included in the received signal are estimated using land clutter signals from at least two points obtained from the land clutter database.

[0063] In step 960, land clutter signals from at least two points can be interpolated based on the location where the received signal is received to estimate the land clutter signals included in the received signal. At this time, the land clutter signals from at least two points can be interpolated based on the distance from each of the at least two points to the land in the corresponding transmission direction and the distance from the location where the received signal is received to the land in the corresponding transmission direction. Specifically, the land clutter signal from one of the at least two points is converted into a land clutter signal at the location where the received signal is received based on the distance to the land in the corresponding transmission direction and the distance from the location where the received signal is received to the land in the corresponding transmission direction, and the land clutter signal from the other of the at least two points is converted into a land clutter signal at the location where the received signal is received based on the distance to the land in the corresponding transmission direction and the distance from the location where the received signal is received to the land in the corresponding transmission direction, and the land clutter signals converted from the land clutter signal of one point and the land clutter signals converted from the land clutter signal of the other point can be averaged to estimate the land clutter signals included in the received signal. Here, converting the received signal into a land clutter signal at the received location can convert the signal strength and temporal location based on the distance to the land, and can convert the signal strength and temporal location by utilizing the fact that the signal strength is inversely proportional to the fourth power of the distance and the time delay is proportional to the distance.

[0064] In step 970, the land clutter signal estimated from the received signal is removed. The removal of the land clutter signal can be performed by a simple subtraction operation of the land clutter signal estimated from the received signal.

[0065] Then, in step 980, the target is detected using the received signal from which the estimated land clutter signal has been removed.

[0066] Next, at step 990, the target is displayed on the display according to the target detection result.

[0067] According to embodiments of the present invention, by removing land clutter signals when detecting anti-ship targets with pulse radar, the target detection capability of the radar can be improved and the probability of false target display can be reduced.

[0068] In addition, the embodiments of the present invention are applicable not only to anti-ship targets but also to TWS (Tracking While Scan, used in ships to mean target assignment for firing) targets, thereby improving the TWS firing accuracy of naval vessels and resolving situations where firing is impossible due to TWS tracking loss, which can enhance the operational capability and survivability of the vessels.

[0069] In addition, embodiments of the present invention may be applied not only to ship radars but also to radars applied to platforms moving on the sea surface and land (e.g., fighter jets, drones, etc.).

[0070] A device according to embodiments of the present invention may include a processor, memory for storing and executing program data, permanent storage such as a disk drive, a communication port for communicating with an external device, and user interface devices such as a touch panel, a key, a button, etc. Methods implemented as software modules or algorithms may be stored on a computer-readable recording medium as computer-readable code or program instructions executable on the processor. Here, computer-readable recording media include magnetic storage media (e.g., ROM (read-only memory), RAM (random-access memory), floppy disks, hard disks, etc.) and optical reading media (e.g., CD-ROM, DVD (Digital Versatile Disc)). Computer-readable recording media may be distributed across networked computer systems, allowing computer-readable code to be stored and executed in a distributed manner. The medium may be readable by a computer, stored in memory, and executed by a processor.

[0071] Embodiments of the present invention may be represented by functional block configurations and various processing steps. These functional blocks may be implemented by various numbers of hardware and / or software configurations that execute specific functions. For example, the embodiment may employ integrated circuit configurations such as memory, processing, logic, look-up tables, etc., which can execute various functions by the control of one or more microprocessors or other control devices. Similar to how components of the present invention may be implemented as software programming or software elements, the embodiment may be implemented in programming or scripting languages ​​such as C, C++, Java, assembler, etc., including various algorithms implemented as combinations of data structures, processes, routines, or other programming configurations. Functional aspects may be implemented as algorithms executed on one or more processors. Additionally, the embodiment may employ prior art for electronic configuration, signal processing, and / or data processing, etc. Terms such as "mechanism," "element," "means," and "configuration" may be used broadly and are not limited to mechanical and physical configurations. The above terms may include the meaning of a series of software processes (routines) in conjunction with processors, etc.

[0072] The specific embodiments described in the embodiments are examples and do not limit the scope of the embodiments in any way. For the sake of brevity of the specification, descriptions of prior electronic configurations, control systems, software, and other functional aspects of said systems may be omitted. Additionally, the connections of lines or connecting members between components shown in the drawings are illustrative of functional connections and / or physical or circuit connections, and may be replaced or additionally represented as various functional connections, physical connections, or circuit connections in actual devices. Furthermore, unless specifically stated as "essential," "importantly," etc., a component may not be absolutely necessary for the application of the present invention.

[0073] The present invention has been described above with reference to its preferred embodiments. Those skilled in the art will understand that the present invention may be embodied in modified forms without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the scope of the claims should be interpreted as being included in the invention.

Claims

Claim 1 Prior to this, a step of transmitting a transmission pulse while moving near land to collect land clutter signals received after the transmission pulse is reflected from land, and constructing a land clutter database by storing land clutter signals, location information, and transmission direction information at each point where the land clutter signals are collected; for target detection, a step of transmitting a transmission pulse to receive a received signal reflected from a target and land; a step of obtaining land clutter signals from at least two points near the location where the received signal was received from the land clutter database; a step of estimating a land clutter signal included in the received signal using the land clutter signals from the at least two points; and a step of removing the estimated land clutter signal from the received signal.The method includes the step of detecting a target using the received signal from which the estimated land clutter signal has been removed, wherein the estimating step comprises estimating the land clutter signal included in the received signal by interpolating the land clutter signals of the at least two points based on the location where the received signal is received, and the estimating step comprises interpolating the land clutter signals of the at least two points based on the distance from each of the at least two points to the land in the corresponding transmission direction and the distance from the location where the received signal is received to the land in the corresponding transmission direction, and the estimating step comprises converting the land clutter signal of one of the at least two points into the land clutter signal of the location where the received signal is received based on the distance to the land in the corresponding transmission direction and the distance from the location where the received signal is received to the land in the corresponding transmission direction, and converting the land clutter signal of the other of the at least two points into the land clutter signal of the location where the received signal is received based on the distance to the land in the corresponding transmission direction and the distance from the location where the received signal is received to the land in the corresponding transmission direction, and the converted land clutter signal of the one point and the converted land of the other point A target detection method using a pulse radar, wherein the land clutter signal included in the received signal is estimated by averaging the clutter signal, and in the estimation step, the land clutter signal at one point is converted into a land clutter signal at the location where the received signal is received, and the land clutter signal at another point is converted into a land clutter signal at the location where the received signal is received, wherein the signal strength and temporal location are converted based on the distance to the land, and the signal strength and temporal location are converted by utilizing the fact that the signal strength is inversely proportional to the fourth power of the distance, and the temporal location is converted by utilizing the fact that the time delay is proportional to the distance. Claim 2 delete Claim 3 A target detection method using pulse radar according to claim 1, wherein the acquiring step is characterized by acquiring land clutter signals at least two points in which the corresponding transmission direction is the same as the transmission direction for the received signal. Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 A clutter database construction unit that, prior to, collects land clutter signals received by reflection from land of a transmission pulse transmitted while moving near land, and constructs a land clutter database by storing land clutter signals, location information, and transmission direction information at each point where the land clutter signals are collected; a storage unit that stores the land clutter database; a pulse transmission / reception unit that transmits a transmission pulse for target detection and receives a reception signal reflected from a target and land by the transmission pulse; and a land clutter removal unit that obtains land clutter signals from at least two points near the location where the reception signal is received from the land clutter database, estimates a land clutter signal included in the reception signal using the land clutter signals from the at least two points, and removes the estimated land clutter signal from the reception signal.The target detection unit includes a target detection unit that detects a target using the received signal from which the estimated land clutter signal has been removed. The land clutter removal unit estimates the land clutter signal included in the received signal by interpolating the land clutter signals of the at least two points based on the location where the received signal was received. The land clutter removal unit interpolates the land clutter signals of the at least two points based on the distance from each of the at least two points to the land in the corresponding transmission direction and the distance from the location where the received signal was received to the land in the corresponding transmission direction. The land clutter removal unit converts the land clutter signal of one of the at least two points into a land clutter signal of the location where the received signal was received based on the distance to the land in the corresponding transmission direction and the distance from the location where the received signal was received to the land in the corresponding transmission direction. It also converts the land clutter signal of the other of the at least two points into a land clutter signal of the location where the received signal was received based on the distance to the land in the corresponding transmission direction and the distance from the location where the received signal was received to the land in the corresponding transmission direction. The converted land of the one point A target detection device using a pulse radar, characterized by estimating a land clutter signal included in a received signal by averaging a clutter signal and a converted land clutter signal at another point, wherein in the land clutter removal unit, converting a land clutter signal at one point into a land clutter signal at the location where the received signal is received, and converting a land clutter signal at another point into a land clutter signal at the location where the received signal is received, involves converting the signal strength and temporal location based on the distance to the land, wherein converting the signal strength and temporal location based on the distance to the land involves converting the signal strength by utilizing the fact that the signal strength is inversely proportional to the fourth power of the distance, and converting the temporal location by utilizing the fact that the time delay is proportional to the distance. Claim 9 delete Claim 10 A target detection device using pulse radar according to claim 8, wherein the land clutter removal unit acquires land clutter signals at least two points in which the corresponding transmission direction is the same as the transmission direction for the received signal. Claim 11 delete Claim 12 delete Claim 13 delete Claim 14 delete

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