JP5503141B2 - Target detection device - Google Patents

Description

  The present invention relates to a target detection device that detects a target such as a land or a building.

  As an apparatus for detecting a target, for example, there is a radar apparatus that transmits a radio wave of a microwave band, receives a reflected wave thereof, and measures a distance and an azimuth from the current position to the target. When using a radar apparatus to detect a target at a long distance with high distance resolution, it is necessary to increase the peak transmission power and emit a narrow pulse signal to space.

  By the way, in recent years, from the viewpoint of effective utilization of radio wave resources, attention has been focused on solid-state radar devices using semiconductor amplifiers that have less unnecessary radiation than electron tubes such as magnetrons and klystrons. However, since the solid-state radar device has a lower transmission power than a radar device using an electron tube, there is a problem that sensitivity to a distant target is lowered.

  In order to solve this problem, by emitting a radio wave of a wide pulse signal (hereinafter referred to as a “modulated pulse signal”) subjected to predetermined modulation, receiving a reflected wave from the target, and performing a pulse compression process An apparatus that can detect a distant target with high distance resolution (hereinafter referred to as “pulse compression radar apparatus”) is known (for example, see Non-Patent Document 1).

  However, in the conventional pulse compression radar apparatus, a reception failure may occur in a facility that receives a broadcast wave, a communication wave, or the like (hereinafter referred to as “radio wave receiving facility”) due to emission of a modulated pulse signal. For example, when the modulated pulse signal emitted by this radar device is located in the image band of a receiver that employs the superheterodyne method, the wide pulse emission unique to the pulse compression radar device causes the electron tube such as magnetron or klystron to be used. Radio waves may be radiated for a longer period of time, and interference may become apparent.

  Therefore, as a countermeasure, for example, when a conventional pulse compression radar apparatus is applied to a land-based weather radar, transmission of a modulated pulse signal is stopped in the azimuth and elevation directions assumed to cause a reception failure. Therefore, a process of providing a sector blank has been performed.

For example, when a conventional pulse compression radar apparatus is mounted on a ship, processing for providing an azimuth blank as shown in FIG. 9 is performed. FIG. 9 shows an anchored ship 1 equipped with a pulse compression radar device, a land 2, a radio wave launchable region 3 indicating a region where a modulated pulse signal can be emitted, and a region where the emission of the modulated pulse signal is restricted. A radio wave emission restriction area 4 shown in FIG. The pulse compression radar device mounted on the ship 1 emits a modulated pulse signal toward the radio wave emission possible region 3 and does not emit the modulated pulse signal in the direction of the land 2 where it is assumed that a reception failure may occur. A launch area is set to avoid a reception failure on the land 2.
Supervised by Takashi Yoshida, “Revised Radar Technology”, The Institute of Telecommunications, May 25, 1999, p275-280

  However, in the conventional pulse compression radar apparatus, it is necessary to set the azimuth and the elevation angle where the radio wave transmission restriction is provided in accordance with the relationship between the area where the radio wave receiving facility is expected to exist and the position of the radar apparatus. Therefore, when a conventional pulse compression radar device is installed on a ship navigating near the beach or a moving object that is moving in a densely populated area for urban heavy rain observation, the radio wave emission restriction area should always be set optimally. It was difficult. Therefore, the conventional pulse compression radar apparatus has a problem that it is difficult to avoid a reception failure due to a modulated pulse signal.

  The present invention has been made to solve the conventional problems, and an object of the present invention is to provide a target detection apparatus capable of avoiding a reception failure due to a modulated pulse signal.

The target detection device of the present invention is mounted on a ship, transmits a modulated pulse signal modulated by a predetermined modulation method, and a signal generated by reflection of the modulated pulse signal at a target from the time when the modulated pulse signal is transmitted. Electric field intensity calculation for calculating the electric field intensity of the modulated pulse signal at a position separated from the apparatus by a predetermined distance in a target detection device comprising target identification means for identifying the time until the received time as a distance from the target Means, position information acquisition means for acquiring current position information, and map data acquisition means for acquiring map data including at least one of map data and chart data, wherein the target identification means includes the modulation pulse Time from when a signal is transmitted to when a signal generated by reflection of the modulated pulse signal at the target is received Transmission power setting means for setting the transmission power of the modulated pulse signal to a smaller value as the length is shorter, the target received specification data for the modulated pulse signal arriving at the target, and the target identifying means includes the modulated pulse. The transmission power of the modulated pulse signal is obtained based on transmission specification data with respect to the signal, and the transmission power setting means is configured to transmit the modulated pulse signal and receive the reflected signal. a direction variable, I der which the modulated pulse signal through the beam sets the transmission specification data based on the relative distance for each area to be irradiated, the electric field intensity of the modulated pulse signal, the The transmission power of the modulated pulse signal is set based on the current position information, the map data, the hull attitude information, and the antenna orientation and elevation information. And a is a configuration of.

  With this configuration, the target detection apparatus of the present invention allows the transmission power setting means to reduce the transmission power of the modulation pulse signal to a smaller value as the distance from the position where the modulation pulse signal is transmitted to the position where the modulation pulse signal is received is shorter. Since it is set, it is possible to avoid a reception failure due to the modulated pulse signal.

Further, according to this configuration, in the target detection device of the present invention, the modulated pulse signal reaches the target from the target identification unit, and on the contrary, the modulation pulse signal reaches the target identification unit from the target. The transmission power of the modulated pulse signal is set in consideration of the characteristics of the return path to be transmitted. Accordingly, obstacles such as interference and interference with the above-described target can be mitigated or avoided with higher accuracy.

In addition, with this configuration, in the target detection device of the present invention, the characteristics of the propagation path of the forward path and the return path described above are added to each area even when the area irradiated with the modulation pulse signal changes. The transmission power of the modulation pulse signal is set. Therefore, even when the targets to be identified using the modulated pulse signal are located in different directions or distributed, obstacles such as interference and interference with these targets are mitigated or avoided more accurately. The

Also, with this configuration, in the target detection device of the present invention, the transmission power setting means is based on the electric field intensity of the modulated pulse signal, current position information , map data , hull attitude information, antenna pointing direction and elevation angle information . Thus, the transmission power of the modulated pulse signal is set, so that it is possible to avoid a reception failure due to the modulated pulse signal.

  Furthermore, the target detection apparatus of the present invention has a configuration in which the modulated pulse signal is any one of radio waves, sound waves, and light that has been processed to enable pulse compression of the reflected signal.

  With this configuration, the target detection apparatus of the present invention can perform positioning and distance measurement by applying a pulse compression technique to a wave signal suitable for various targets and fields.

  The present invention can provide a target detection apparatus having an effect of avoiding a reception failure due to a modulated pulse signal.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The target detection device according to the present invention will be described with reference to an example in which the target detection device is applied to a radar device mounted on a ship and using microwave waves. Moreover, in this embodiment, a target means the land, its coastline, the land, or a building on the sea. In the following description, when the radar apparatus 10 detects a target, it is assumed that there is a radio wave receiving facility near the detected target.

  First, the configuration of an embodiment of a radar apparatus according to the present invention will be described.

  As shown in FIG. 1, a radar apparatus 10 according to the present embodiment includes an electric field intensity calculation unit 11, a specification data holding unit 12, a gyro 13, a global positioning system (hereinafter referred to as “GPS”) 14, and a map data holding unit. 15, a transmission timing instruction unit 16, an electric field strength map generation unit 17, a threshold data holding unit 18, and a reception failure map generation unit 19. The radar apparatus 10 further includes a reception failure determination unit 20, a modulation specification instruction unit 21, a modulation unit 22, a transmission unit 23, an antenna unit 24, and a reception unit 25.

  The electric field strength calculation unit 11 calculates the electric field strength at an arbitrary distance with respect to the position of the radar apparatus 10, and the electric field strength of the pulse signal wave based on the modulated pulse signal in the radio wave receiving facility assumed to exist near the target. Is supposed to calculate. This electric field strength can be calculated by, for example, calculating the received power at the radio wave receiving facility that is separated from the radar apparatus 10 by the distance r, using Equation 1. The electric field strength calculation unit 11 constitutes electric field strength calculation means according to the present invention.

The explanation of each variable is shown below.
Pr: Received power at a position r away from the radar apparatus 10 (= square of electric field strength)
Pt: Peak transmission power [W] of the modulated pulse signal
τ: Modulation pulse width of modulation pulse signal [seconds]
Gt: antenna gain [times] of the modulated pulse signal
Gr: Received antenna gain of radio wave reception equipment [times]
Grec: receiver gain of radio wave reception facility with respect to transmission wavelength of modulated pulse signal [times]
Ae: Opening area of reception antenna of radio wave reception facility [m ² ]
λ: transmission wavelength of modulated pulse signal [m]

  Among the variables on the right side of Equation 1, Pt, τ, Gt, and λ are variables related to transmission in the radar apparatus 10 and are hereinafter referred to as “transmission specifications”. Of the variables on the right side of Equation 1, Gr, Grec, and Ae are variables related to reception at the radio wave reception facility, and are hereinafter referred to as “reception specifications”.

  The specification data holding unit 12 holds the transmission specification and reception specification data shown in Equation 1, and is read out by the electric field strength calculation unit 11. Here, the transmission specification data is self-evident because it is determined when the radar apparatus 10 is operated. On the other hand, the data of the receiving specifications differ depending on the radio wave receiving equipment that is the target of avoiding reception disturbances. However, the receivers provided in each radio wave receiving equipment conform to the standards proposed by the standards bodies related to broadcast waves and communication waves. Since it is designed on the basis of this, it is possible to determine the data of the receiving specifications with reference to the standard. It is also possible to determine the data of the receiving specifications by conducting an experiment in advance.

  The gyro 13 detects the attitude of the hull, and determines the roll angle, pitch angle, and yaw angle for each of the predetermined roll axis (x axis), pitch axis (y axis), and yaw axis (z axis). These data are obtained and outputted as hull attitude information every predetermined time. In this embodiment, since the example which mounts the radar apparatus 10 on a ship is given, it was set as the structure provided with the gyroscope 13, However, For example, when mounting the radar apparatus 10 in the building fixed on the ground, the gyroscope 13 is abbreviate | omitted. Also good.

  The GPS 14 receives radio waves from a GPS (Global Positioning System) satellite, and acquires latitude and longitude information (hereinafter referred to as “current position information”) indicating the current position of the ship at predetermined time intervals. . The GPS 14 constitutes position information acquisition means according to the present invention.

  The map data holding unit 15 holds map data and nautical chart data (hereinafter collectively referred to as “map data”), and based on the current position information acquired by the GPS 14, the current position of the radar apparatus 10 is determined. Central map data is generated every predetermined time. Here, the map data holding unit 15 constitutes map data acquisition means according to the present invention. The radar apparatus 10 can acquire information on the surrounding environment of the radar apparatus 10 by referring to the map data. The map data held by the map data holding unit 15 may be at least one of map data and nautical chart data. Moreover, it is good also as a structure provided with the radio | wireless communication means which replaces with the map data holding | maintenance part 15, and acquires map data by radio | wireless communication, for example via the internet.

  The transmission timing instruction unit 16 generates a transmission trigger signal for instructing the timing for transmitting the modulated pulse signal based on a predetermined pulse repetition interval (PRI), and the generated transmission trigger signal is used as the electric field strength. The data is output to the map generation unit 17, the reception failure map generation unit 19, the reception failure determination unit 20, and the modulation unit 22.

  The electric field strength map generation unit 17 generates a map (hereinafter referred to as “electric field strength map”) indicating the electric field strength in the radar track of the radar apparatus 10. Specifically, the electric field strength map generator 17 receives the electric field strength data from the electric field strength calculator 11, the attitude information of the hull from the gyro 13, the current position information from the GPS 14, the map data from the map data holding unit 15, and the transmission timing instruction. A transmission trigger signal is input from the unit 16 and information on the directivity and elevation of the antenna 24a (described as antenna information in the drawing) is input from the antenna unit 24, and an electric field strength map is generated. An example of the electric field strength map generated by the electric field strength map generating unit 17 is shown in FIG.

  The electric field intensity map shown in FIG. 2 shows a state in which the ship 31 on which the radar apparatus 10 is mounted is navigating in the direction indicated by the dotted arrow near the coast of the land 32, and the equal electric field centered on the ship 31. An intensity line 33 is drawn. That is, the electric field strength map is obtained by combining the current position information of the ship 31, the attitude information of the hull, the electric field strength data, and the map data. This field strength map is updated by the field strength map generation unit 17 every time a transmission trigger signal is received.

  Returning to FIG. 1, the threshold data holding unit 18 holds field strength threshold data for determining whether or not a reception failure occurs in a radio wave reception facility that is a target for avoiding a reception failure. . This electric field strength threshold is a value determined based on the desired signal reception power expected by the receiver in the radio wave reception facility that is a target for avoiding reception interference. For example, the threshold data holding unit 18 holds a value twice the desired signal received power of the receiver as the electric field strength threshold. The desired signal received power of the receiver is determined by referring to a standard proposed by a standards body regarding broadcast waves, communication waves, etc., or by conducting an experiment in advance.

  Further, the electric field strength threshold data held by the threshold data holding unit 18 will be described with reference to FIG. In FIG. 3, the horizontal axis indicates the distance from the radar apparatus 10 to the target, and the vertical axis indicates the electric field strength at the target position.

  As shown in FIG. 3, the electric field strength of the modulated pulse signal emitted by the radar apparatus 10 is inversely proportional to the square of the distance, and the electric field strength increases as the peak transmission power increases. By determining the threshold value, it is determined whether there is a possibility that a reception failure may occur in the radio wave reception facility due to the distance from the radar device 10 to the target and the electric field strength in the radio wave reception facility calculated by the electric field strength calculation unit 11. It can be determined.

  Returning to FIG. 1, the reception failure map generation unit 19 holds the transmission trigger signal output from the transmission timing instruction unit 16, the field strength map data generated by the field strength map generation unit 17, and the threshold data holding unit 18. Field strength threshold data is input. The reception failure map generation unit 19 compares the input field strength map data with the field strength threshold data, and determines the possibility of reception failure according to the amount of electric field strength in the radio wave reception facility with respect to the field strength threshold. A map indicating presence / absence (hereinafter referred to as “reception failure map”) is generated. An example of the reception failure map is shown in FIG.

  The reception failure map shown in FIG. 4 is based on the field strength map generated by the field strength map generation unit 17 and the field strength threshold data, the region 41 where there is no possibility of reception failure, and the occurrence of reception failure. The regions 42 to 45 having the possibility of the above are shown. The reception failure map is updated by the reception failure map generation unit 19 every time a transmission trigger signal is received.

  Returning to FIG. 1, the reception failure determination unit 20 inputs information on the directivity and elevation of the antenna 24 a from the antenna unit 24, and based on this information, determines the traveling direction (beam direction) of the modulated pulse signal emitted by the antenna 24 a. It comes to detect. The reception failure determination unit 20 determines whether or not the traveling direction of the detected modulated pulse signal overlaps with a region where there is a possibility of reception failure shown in the electric field strength map.

  Here, the reception failure determination unit 20 may cause a reception failure in the next emission of the modulated pulse signal when the traveling direction of the modulation pulse signal overlaps with a region where the reception failure may occur. A signal indicating this is output to the modulation specification instruction unit 21 every time a transmission trigger signal is received. At this time, the reception failure determination unit 20 refers to the threshold data held by the threshold data holding unit 18, and the electric field strength of the next modulated pulse signal is determined from the electric field strength threshold in a region where the reception failure may occur. Data indicating how much is exceeded (hereinafter referred to as “threshold excess data”) is also output to the modulation specification instruction unit 21 together.

  The modulation specification instruction unit 21 relates to the modulation pulse signal based on the transmission specification and reception specification data held by the specification data holding unit 12, the determination result of the reception failure determination unit 20, and the threshold excess data. The data value of the transmission specification is instructed to the modulation unit 22.

  Specifically, the modulation specification instruction unit 21 instructs the modulation unit 22 to set the transmission power of the modulation pulse signal according to the distance from the radar apparatus 10 to the target. For example, the modulation specification instruction unit 21 instructs the modulation unit 22 to transmit the modulation pulse signal with the maximum power to a region where there is no possibility of reception failure due to the modulation pulse signal. In addition, for example, the modulation specification instruction unit 21 transmits a modulation pulse signal with power corresponding to the distance from the area to the radar apparatus 10 to a region where a reception failure due to the modulation pulse signal may occur. The modulation unit 22 is instructed to do so. The modulation specification instructing unit 21 constitutes transmission power setting means according to the present invention.

  The modulation unit 22 receives a transmission trigger signal from the transmission timing instruction unit 16 and generates a modulated pulse signal based on an instruction from the modulation specification instruction unit 21 every time the transmission trigger signal is received. This modulated pulse signal includes, for example, a signal component having a pulse width of about 20 μs to 50 μs and modulated by a predetermined modulation method. Examples of the modulation method include a chirp modulation method and a phase modulation method.

  Here, the processing of the modulation unit 22 will be specifically described with reference to FIG. 5A shows a transmission trigger signal generated by the transmission timing instruction unit 16 based on the PRI, and FIGS. 5B to 5E illustrate the modulated pulse signals A to D generated by the modulation unit 22, respectively. ing.

  First, the modulation pulse signal A shown in FIG. 5B is a modulation pulse signal when transmitting with the maximum power. The modulation pulse signal A is generated by the modulation unit 22 when there is an instruction from the modulation specification instruction unit 21 to transmit the modulation pulse signal with the maximum power.

  Also, the modulation pulse signal B shown in FIG. 5C is generated when the modulation specification instruction unit 21 instructs to set the transmission power of the modulation pulse signal to a predetermined value (for example, half of the maximum power). 22 is generated. In this case, instead of the process of reducing the amplitude of the modulation pulse signal, the modulation unit 22 may perform a process of shortening the pulse width of the modulation pulse signal as in the modulation pulse signal C shown in FIG. it can.

  Further, as shown in FIG. 5E, the modulation unit 22 does not generate a modulation pulse signal (in other words, the amplitude when the modulation specification instruction unit 21 instructs to stop transmission of the modulation pulse signal). (A modulation pulse signal D having a value of zero is generated).

  Returning to FIG. 1, the transmission unit 23 receives the modulation pulse signal generated by the modulation unit 22, frequency-converts the modulation pulse signal to a frequency to be emitted into space, performs power amplification, and outputs the result to the antenna unit 24. It has become. The transmitter 23 constitutes a target identifying unit according to the present invention.

  The antenna unit 24 emits radio waves and receives reflected waves with respect to an area of 360 degrees around the ship, and driving for setting the scanning area of the antenna 24a by changing the azimuth angle of the antenna 24a. Part 24b. The aerial unit 24 receives a reflected wave signal in which each radio wave based on the modulated pulse signal is reflected by the target, and outputs the received signal to the receiving unit 25. In addition, the antenna unit 24 outputs information on the directivity and elevation angle of the antenna 24 a to the electric field strength map generation unit 17 and the reception failure determination unit 20. In the present embodiment, the drive unit 24b is described as changing only the azimuth angle of the antenna 24a. However, the drive unit 24b changes at least one of the azimuth angle and the elevation angle of the antenna 24a. Also good.

  The receiving unit 25 performs power amplification, detection, and pulse compression processing of the reflected wave signal from the antenna unit 24 to detect a target land or building. Further, when the receiving unit 25 detects the target, the distance from the radar device 10 to the target is determined by using, for example, the monotonic decrease rule of the cell average value shown in FIG. 2 of Japanese Patent Application Laid-Open No. 2003-227871. It comes to ask for. The receiving unit 25 constitutes a target identifying unit according to the present invention.

  Next, the operation of the radar apparatus 10 in this embodiment will be described with reference to FIGS. FIG. 6 is a flowchart showing the operation of the radar apparatus 10.

  The electric field strength calculation unit 11 reads the data of the transmission specifications from the specification data holding unit 12, calculates the electric field strength at an arbitrary distance with respect to the position of the radar apparatus 10 (step S11), and uses the calculated data as the electric field. Output to the intensity map generator 17.

  The gyro 13 obtains hull attitude information by obtaining the hull roll angle, pitch angle, and yaw angle (step S12), and outputs the obtained hull attitude information to the electric field strength map generation unit 17 at predetermined time intervals. . If the attitude information of the hull is known, the attitude information of the antenna unit 24 mounted on the hull can also be obtained.

  The GPS 14 receives the current position information of the ship by receiving radio waves from GPS satellites (step S13), and the acquired current position information of the ship is sent to the map data holding unit 15 and the electric field strength map generating unit 17 every predetermined time. Respectively.

  The map data holding unit 15 acquires map data in which the center of the map or nautical chart is the current position of the ship (step S14), and outputs the acquired map data to the electric field strength map generation unit 17 every predetermined time.

  The electric field strength map generation unit 17 receives the electric field strength data from the electric field strength calculation unit 11, the attitude information of the hull from the gyro 13, the current position information from the GPS 14, the map data from the map data holding unit 15, and the transmission trigger from the transmission timing instruction unit 16. A signal and information on the directivity and elevation angle of the antenna 24a are input from the antenna unit 24, and an electric field strength map (see FIG. 2) is generated (step S15). The electric field strength map generation unit 17 outputs the generated electric field strength map data to the reception failure map generation unit 19.

  The reception failure map generation unit 19 inputs the field strength map data generated by the field strength map generation unit 17 and the field strength threshold data held by the threshold data holding unit 18, and the input field strength map data and The data of the electric field strength threshold value is compared, and a reception failure map (see FIG. 4) is generated according to the amount of electric field strength in the radio wave receiving facility with respect to the electric field strength threshold value (step S16). In addition, the reception failure map generation unit 19 outputs the generated reception failure map data to the reception failure determination unit 20.

  The reception failure determination unit 20 generates a reception failure due to the modulated pulse signal based on the information on the directivity and elevation of the antenna 24a input from the antenna unit 24 and the data of the reception failure map input from the reception failure map generation unit 19. It is determined whether or not to perform (step S17).

  Specifically, the reception failure determination unit 20 detects the traveling direction of the modulated pulse signal emitted by the antenna 24a, and the traveling direction of the detected modulated pulse signal indicates the possibility of occurrence of reception failure indicated in the electric field strength map. It is determined whether or not it overlaps the area where there is. Here, the reception failure determination unit 20 may cause a reception failure in the next emission of the modulated pulse signal when the traveling direction of the modulation pulse signal overlaps with a region where the reception failure may occur. Each time a transmission trigger signal is received, a signal indicating this is output to the modulation specification instruction unit 21, and the electric field strength of the next modulated pulse signal is a field strength threshold value in a region where a reception failure may occur. The threshold value excess data indicating how much is exceeded is also output to the modulation specification instruction unit 21.

  The modulation specification instruction unit 21 generates a modulated pulse signal based on the determination result of the reception failure determination unit 20 and outputs the modulated pulse signal to the transmission unit 23.

  First, for the region where the reception failure determination unit 20 determines that no reception failure occurs even if the amplitude of the modulation pulse signal is set to the maximum value (determination 1), the modulation specification instruction unit 21 sets the modulation pulse. The modulation unit 22 is instructed to set the signal amplitude to the maximum value and transmit at the maximum power (step S18).

  Further, if the reception failure determination unit 20 sets the amplitude of the modulated pulse signal to the maximum value, a reception failure may occur, but if the amplitude of the modulation pulse signal is reduced (or the pulse width is shortened), the reception failure is avoided. The modulation specification instruction unit 21 instructs the modulation unit 22 to reduce the amplitude (or shorten the pulse width) of the modulation pulse signal in accordance with the distance for the area determined to be able to be determined (determination 2). (Step S19).

  Further, the modulation specification is applied to the region in which the reception failure determination unit 20 determines that the reception failure cannot be avoided (determination 3) even if the amplitude of the modulated pulse signal is reduced (or the pulse width is reduced). The instruction unit 21 instructs the modulation unit 22 to stop transmission of the modulation pulse signal (in other words, generate a modulation pulse signal having an amplitude value of zero) (step S20).

  The modulation unit 22 generates a modulation pulse signal (for example, FIGS. 5B to 5E) in which the amplitude (or pulse width) of the modulation pulse signal is set based on an instruction from the modulation specification instruction unit 21 (steps b). S21) and output to the transmitter 23.

  The transmission unit 23 frequency-converts the input modulated pulse signal to a frequency to be emitted into space, performs power amplification, and transmits the result via the antenna unit 24 (step S22). The antenna unit 24 reflects the light reflected by the target. The wave signal is received (step S23) and output to the receiving unit 25. The receiving unit 25 performs power amplification, detection, and pulse compression processing of the reflected wave signal from the antenna unit 24.

  The operation of the radar apparatus 10 described above will be specifically described with reference to FIGS. FIG. 7 is a diagram illustrating a state in which the ship 31 on which the radar apparatus 10 is mounted is navigating in the direction indicated by the dotted arrow near the coast of the land 32.

  As described above, the reception failure determination unit 20 generates a reception failure map (see FIG. 4) by determining the amount of electric field strength in the radio wave reception facility with respect to the electric field strength threshold. The modulation specification instruction unit 21 performs the following processing based on the reception failure map.

  The modulation specification instruction unit 21 instructs the modulation unit 22 to emit a modulation pulse signal with the maximum transmission power for the region 51 where there is no possibility of occurrence of reception failure.

  Further, if the region 53 is a region in which the reception failure cannot be avoided even if the amplitude of the modulated pulse signal is reduced (or the pulse width is shortened), the modulation specification instruction unit 21 The modulation unit 22 is instructed to stop the emission of the modulated pulse signal.

  Further, the regions 52 and 54 may cause a reception failure if the amplitude of the modulation pulse signal is set to the maximum value, but if the amplitude of the modulation pulse signal is reduced, the reception failure can be avoided. If there is, the modulation specification instructing unit 21 instructs the data of the amplitude value of the modulation pulse signal that can avoid the reception failure to the areas 52 and 54, respectively.

  Specifically, the modulation specification instruction unit 21 instructs the modulation unit 22 to set the amplitude of the modulation pulse signal to, for example, ¼ of the maximum value for the region 52. The modulation specification instruction unit 21 instructs the modulation unit 22 to set the amplitude of the modulation pulse signal to, for example, ½ of the maximum value for the region 54 farther from the region 52. That is, the radar apparatus 10 mounted on the ship 31 can dynamically set the amplitude of the modulated pulse signal and dynamically avoid reception failures.

  As described above, according to the radar apparatus 10 of the present embodiment, the modulation pulse is shorter as the distance from the position where the modulation pulse signal is transmitted to the position where the modulation pulse signal is received is shorter using the current position information and the map information. Since the modulation specification instruction unit 21 for setting the transmission power of the signal to a small value is provided, it is possible to avoid a reception failure due to the modulated pulse signal.

  Next, another aspect of the present embodiment will be described with reference to FIG. FIG. 8 is a diagram illustrating a configuration of the modulation unit 60 obtained by changing the configuration of the modulation unit 22 in the above-described embodiment. Other configurations are the same as those in FIG.

  As shown in FIG. 8, the modulation unit 60 includes modulation pulse signal generators 61 to 64, a modulation pulse signal selection unit 65, and a D / A conversion unit 66.

  The modulation pulse signal generators 61 to 64 generate modulation pulse signals having different amplitudes based on the transmission trigger signal.

  Specifically, each of the modulation pulse signal generators 61 to 64 holds table data for generating a modulation pulse signal, and generates a modulation pulse signal composed of a digital signal based on the transmission trigger signal. It is. In the example illustrated in FIG. 8, the modulation pulse signal generators 61 to 64 generate modulation pulse signals having maximum amplitude, 1/2 of maximum amplitude, 1/4 of maximum amplitude, and zero amplitude, respectively.

  The modulation pulse signal selection unit 65 selects any one of the modulation pulse signal generators 61 to 64 based on an instruction from the modulation specification instruction unit 21.

  The D / A converter 66 converts the modulated pulse signal, which is one of the outputs of the modulated pulse signal generators 61 to 64 selected by the modulated pulse signal selector 65, into an analog signal, and transmits the transmitter 23 (not shown). To output.

  With this configuration, the modulation unit 60 can easily generate a modulation pulse signal based on an instruction from the modulation specification instruction unit 21.

  In the above-described embodiment, the processing for reducing the peak transmission power has been described by taking an example of performing the amplitude reduction or the pulse width reduction. However, the present invention is not limited to these, and the peak transmission is performed. A similar effect can be obtained if the process reduces power.

  In the above-described embodiment, the example in which the radar apparatus 10 is mounted on a ship has been described. However, the present invention is not limited to this. For example, the same effect can be obtained even when the radar apparatus 10 is mounted on a moving body such as a vehicle or an aircraft, or a weather radar that is fixedly installed.

  Furthermore, in the above-described embodiment, the radar apparatus 10 using the microwave band radio wave has been described as an example. However, the present invention is not limited to this, and the radio wave other than the microwave band or the ultrasonic wave is not limited thereto. The same effect can be obtained even when applied to an apparatus for detecting a target using infrared rays, light, or the like.

  Further, in the above-described embodiment, chirp modulation for realizing pulse compression of the modulated pulse signal is performed based on a code sequence having “steep autocorrelation characteristics” such as a PN code and a GOLD code. May be substituted.

  Furthermore, in the above-described embodiment, the target may be a distributed target such as a cloud, fog, or wave.

  Further, in the above-described embodiment, the target that is subject to reception failure or the like by the modulated pulse signal is not limited to the radio wave receiving facility, and for example, performance deteriorates due to interference or interference caused by the incoming modulated pulse signal, or malfunction or the like It may be a device that may cause a failure.

  As described above, in the target detection apparatus according to the present invention, obstacles such as interference and interference with the target described above due to the modulated pulse signal are mitigated or avoided with higher accuracy. Therefore, it is useful as a target detection device.

The block diagram which shows the structure of the radar apparatus in one Embodiment of this invention. The figure which shows an example of the electric field strength map which the electric field strength map production | generation part of the radar apparatus in one Embodiment of this invention produces | generates Explanatory drawing of the electric field strength threshold value which the threshold value data holding part of the radar apparatus in one embodiment of the present invention holds The figure which shows an example of the reception obstacle map which the reception obstacle map production | generation part of the radar apparatus in one Embodiment of this invention produces | generates. Explanatory drawing of the process of the modulation | alteration part of the radar apparatus in one Embodiment of this invention The flowchart which shows operation | movement of the radar apparatus in one Embodiment of this invention. Explanatory drawing of the operation | movement during the navigation of the ship carrying the radar apparatus in one Embodiment of this invention The figure which shows another aspect in the radar apparatus in one Embodiment of this invention. Explanatory drawing of the process which provides an azimuth blank in the conventional radar apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Radar apparatus 11 Electric field strength calculation part 12 Specification data holding part 13 Gyro 14 GPS
DESCRIPTION OF SYMBOLS 15 Map data holding part 16 Transmission timing instruction | indication part 17 Electric field strength map production | generation part 18 Threshold value data holding part 19 Reception failure map production | generation part 20 Reception failure determination part 21 Modulation specification instruction | indication part 22 Modulation part 23 Transmission part 24 Aerial part 24a Antenna 24b Drive unit 25 Receiver unit 31 Ship 32 Land 33 Equivalent electric field strength line 41 to 45, 51 to 54 Area 60 Modulator 61 to 64 Modulation pulse signal generator 65 Modulation pulse signal selection unit 66 D / A conversion unit

Claims (2)

A modulated pulse signal that is mounted on a ship and modulated by a predetermined modulation method is transmitted, and a time from when the modulated pulse signal is transmitted to when a signal generated by reflection of the modulated pulse signal at a target is received In the target detection apparatus comprising target identification means for identifying the distance from the target,
At least one of electric field intensity calculation means for calculating the electric field intensity of the modulated pulse signal at a position away from the apparatus by a predetermined distance, position information acquisition means for acquiring current position information, map data and chart data Map data acquisition means for acquiring map data including,
The target identifying means reduces the transmission power of the modulated pulse signal to a smaller value as the time from when the modulated pulse signal is transmitted to when the signal generated by reflection of the modulated pulse signal at the target is received is shorter. Transmission power setting means for setting to the modulation pulse signal arriving at the target, based on the target reception specification data for the modulation pulse signal and the transmission specification data the target identification means has for the modulation pulse signal , Obtaining the transmission power of the modulated pulse signal,
The transmission power setting means varies a beam direction of an antenna used for transmission of the modulated pulse signal and reception of the reflected signal, and a relative distance for each region irradiated with the modulated pulse signal via the beam what der which sets the transmission specification data based on the field strength of the modulated pulse signal, the current position information, the map data, and orientation information of the hull, the directivity orientation and elevation information of the antenna A target detection apparatus that sets a transmission power of the modulated pulse signal based on the target. The target detection apparatus according to claim 1, wherein the modulated pulse signal is any one of radio waves, sound waves, and light that have been processed to enable pulse compression of the reflected signal. Detection device.

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