Radar device, and observation object selection method in radar device
The radar device enhances accuracy by dividing the short-long boundary region and comparing observation data characteristics to select the optimal pulse signal, addressing the limitations of existing weather radars with solid-state elements.
Patent Information
- Application Number
- JP2024011673
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-01-30
- Publication Date
- 2025-08-12
AI Technical Summary
Weather radars using solid-state elements face limitations in achieving high output power and cannot effectively utilize both short and long pulse signals in overlapping observation regions, leading to inaccurate observation data.
A radar device that alternately transmits short and long pulse signals and employs an observation target selection mechanism to divide the short-long boundary region by azimuth angle and distance, comparing characteristics of observation data to select the appropriate pulse signal for each sector.
Improves radar accuracy by selecting the most suitable pulse signal for each sector, enhancing data sensitivity, reducing noise and clutter interference, and providing highly accurate observation results.
Smart Images
Figure 2025117032000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a radar device and a method for selecting an observation target in the radar device. [Background technology]
[0002] A weather radar transmits pulse signals while rotating its antenna in azimuth and changing the elevation angle, thereby acquiring observation data of a three-dimensional area centered on the radar.
[0003] Weather radars that use solid-state elements in their transmitters have not yet achieved the same output power as electron tube types, and since they cannot observe long distances using only short pulse signals, they use long pulse signals and pulse compression technology for observation. As shown in Figure 7, this type of weather radar alternately transmits and receives short and long pulse signals, observing nearby areas with short pulse signals and distant areas with long pulse signals (Non-Patent Document 1). [Prior art documents] [Non-patent literature]
[0004] [Non-Patent Document 1] Ministry of Internal Affairs and Communications, "Weather Radar Overview", [online], December 11, 2015, Toshiba Corporation, [Retrieved December 19, 2023], Internet<URL: https: / / www.soumu.go.jp / main_content / 000394203.pdf> Summary of the Invention [Problem to be solved by the invention]
[0005] When observing using both short pulse signals and long pulse signals in this manner, regions observable by both short pulse signals and long pulse signals occur. In these regions, both observation data by short pulse signals and observation data by long pulse signals exist. However, in the past, a uniform rule was established: in an observation region below a predetermined distance (distance from the radar device), the observation target was assumed to be a short pulse signal and observation data by short pulse signals was adopted; and in an observation region above that distance, the observation target was assumed to be a long pulse signal and observation data by long pulse signals was adopted. Therefore, even in these regions, even though both observation data by short pulse signals and observation data by long pulse signals exist, the system was set to observe only one of the pulse signals (usually the long pulse signal), which meant that the observation data could not be effectively utilized, and there was room for improvement in terms of radar device accuracy.
[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a radar device capable of providing highly accurate observation results and a method for selecting an observation target in the radar device. [Means for solving the problem]
[0007] In order to solve the above problem, the invention of claim 1 is a radar device that alternately transmits short pulse signals and long pulse signals having a pulse width longer than that of the short pulse signals, and includes an observation target selection means, wherein when performing signal processing of a short-long boundary region that is an observation region using the short pulse signals and an observation region using the long pulse signals, the observation target selection means divides the short-long boundary region by a predetermined azimuth angle, compares characteristics of observation data using the short pulse signals with characteristics of observation data using the long pulse signals for each of the predetermined azimuth angles, and selects, based on the result of the comparison, whether the short pulse signal or the long pulse signal will be the observation target for each of the predetermined azimuth angles.
[0008] The invention described in claim 2 is characterized in that, in the radar device described in claim 1, the observation target selection means divides the short-long boundary area by a predetermined azimuth angle and a predetermined distance, performs the comparison for each of the predetermined azimuth angle and the predetermined distance, and performs the selection for each of the predetermined azimuth angle and the predetermined distance based on the result of the comparison.
[0009] The invention of claim 3 is the radar device of claim 1 or 2, wherein the characteristic of the observation data is at least one of an S / N ratio, a reflection intensity, a Doppler velocity, and a velocity width.
[0010] The invention of claim 4 is a method for selecting an observation target in a radar device that alternately transmits short pulse signals and long pulse signals having a pulse width longer than that of the short pulse signals, the method comprising the steps of: when performing signal processing on a short-long boundary area that is an observation area using the short pulse signals and also an observation area using the long pulse signals, dividing the short-long boundary area by a predetermined azimuth angle; comparing, for each of the predetermined azimuth angles, characteristics of observation data using the short pulse signals with characteristics of observation data using the long pulse signals; and selecting, for each of the predetermined azimuth angles, whether to observe the short pulse signals or the long pulse signals based on a result of the comparison. [Effects of the Invention]
[0011] According to the inventions of claims 1 and 4, when performing signal processing in a short-long boundary region that is an observation region using short pulse signals and an observation region using long pulse signals, it is possible to select whether to observe short pulse signals or long pulse signals for each azimuth angle, thereby obtaining more appropriate observation data and improving the accuracy of the radar device.In addition, since the pulse signals to be observed are selected by comparing the characteristics of the observation data, it is possible to obtain appropriate observation data according to the observation purpose.
[0012] Furthermore, according to the invention described in claim 2, the short / long boundary area is divided not only by azimuth angle but also by distance (distance from the radar device), and pulse signals to be observed are selected for each of the more subdivided areas, thereby making it possible to obtain more appropriate observation data and further improve the accuracy of the radar device.
[0013] Furthermore, according to the invention of claim 3, since it is only necessary to compare at least one of the S / N ratio, reflection intensity, Doppler velocity, and velocity width of the observation data, it is possible to simplify the process of selecting the pulse signal to be observed. Furthermore, when comparing the S / N ratio of the observation data, it is possible to select a pulse signal with higher sensitivity. Furthermore, when comparing the reflection intensity of the observation data, it is possible to eliminate the influence of long pulse signals. Furthermore, when comparing the Doppler velocity of the observation data, it is possible to eliminate the influence of clutter. Furthermore, when comparing the velocity width of the observation data, it is possible to select a pulse signal that provides observation data with less variance. [Brief explanation of the drawings]
[0014] [Figure 1] 1 is a block diagram showing a schematic configuration of a radar device according to a first embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing an observation area using a short pulse signal and a long pulse signal in a radar device according to a first embodiment of the present invention. [Figure 3] 3 is a schematic diagram showing a division mode of a short-long boundary area and an example of selection of an observation target signal in the radar device according to the first embodiment of the present invention. FIG. [Figure 4] 5 is a flowchart showing a procedure for selecting an observation target in the radar device according to the first embodiment of the present invention. [Figure 5] 10 is a schematic diagram showing a division mode of a short-long boundary area and an example of selection of an observation target signal in a radar device according to a second embodiment of the present invention. FIG. [Figure 6] 10 is a flowchart showing a procedure for selecting an observation target in a radar device according to a second embodiment of the present invention. [Figure 7] 1 is a diagram for explaining a transmission / reception method of a radar device that alternately transmits and receives short pulse signals and long pulse signals; DETAILED DESCRIPTION OF THE INVENTION
[0015] The present invention will be described below based on the illustrated embodiments.
[0016] (Embodiment 1) 1 to 4 show a first embodiment of the present invention, and Fig. 1 is a block diagram showing a schematic configuration of a weather radar (radar device) 1 according to this embodiment. This weather radar 1 mainly comprises an antenna unit 11 and a processing control unit 12. The antenna unit 11 comprises a radar transmitting unit 111, a radar receiving unit 112, and a radar driving unit 113, and the processing control unit 12 comprises a signal processing unit 121, an observation target selecting unit (observation target selecting means) 122, a display unit 123, and a control unit 124.
[0017] The weather radar 1 according to this embodiment is a radar device that uses a solid-state element in its transmitter. As shown in Fig. 7, this weather radar 1 alternately transmits a short pulse signal (P0N) and a long pulse signal (Q0N) whose pulse width is longer than that of the short pulse signal (P0N), and detects targets such as rain clouds in a wide observation area and acquires weather information by synthesizing nearby observation signals obtained by the short pulse signal (P0N) and distant observation signals obtained by the long pulse signal (Q0N).
[0018] The radar transmitter 111 transmits a short pulse signal (P0N) and a long pulse signal (Q0N) into the air via an antenna. The radar receiver 112 receives the short pulse signal (P0N) and the long pulse signal (Q0N) via the antenna as reflected waves returned from targets such as rain clouds. The radar driver 113, under the control of the controller 124, controls the azimuth and elevation angles of the antenna.
[0019] The signal processing unit 121, under the control of the control unit 124, performs signal processing such as clutter removal on the pulse signals output from the radar transmitting unit 111 and the radar receiving unit 112, and outputs the signals to the observation target selecting unit 122.
[0020] The observation target selection unit 122 is a mechanism that performs signal processing for the short-long boundary region 2, which is an area that can be observed using both the short pulse signal (P0N) and the long pulse signal (Q0N). Specifically, it selects whether the short pulse signal (P0N) or the long pulse signal (Q0N) will be the observation target in the short-long boundary region 2.
[0021] To explain the short-long boundary region 2, the observation region of the weather radar 1 is shown in FIG. 2. The weather radar 1 according to this embodiment alternately transmits a short pulse signal (P0N) and a long pulse signal (Q0N), observing areas close to the radar device using the short pulse signal (P0N) and areas far from the radar device using the long pulse signal (Q0N). In this case, as shown in FIG. 2, the observation region is divided outward from the center where the weather radar 1 is located into an observation region observable only by the short pulse signal (P0N), a short-long boundary region 2 observable by both the short pulse signal and the long pulse signal, and an observation region observable only by the long pulse signal (Q0N). Note that the short-long boundary region 2 is determined by the pulse lengths of the short pulse signal (P0N) and the long pulse signal (Q0N), and therefore its range is usually set according to the specifications of the radar device.
[0022] There are two types of observation data obtained by the short pulse signal (P0N) and the long pulse signal (Q0N) in the short-long boundary region 2. When performing signal processing of the short-long boundary region 2, the observation target selection unit 122 selects, as needed, which of these two pulse signals to use as the observation target.
[0023] FIG. 3 is a schematic diagram showing a division mode of the short-long boundary region 2 and an example of selection of an observation target signal in the weather radar 1 according to this embodiment. Using the example of FIG. 3, the details of the processing by the observation target selection unit 122 will be described. First, the observation target selection unit 122 divides the short-long boundary region 2 by a predetermined azimuth angle. Specifically, the short-long boundary region 2 is divided into three sectors: a sector S1 with an azimuth angle of 0 to θ1 degrees, a sector S2 with an azimuth angle of θ1 to (θ1+θ2) degrees, and a sector S3 with an azimuth angle of (θ1+θ2) to (θ1+θ2+θ3) degrees. Note that the central angles θ1, θ2, and θ3 of the sectors may be the same or different. For the sake of explanation, FIG. 3 divides only the azimuth angle range of 0 to (θ1+θ2+θ3) degrees, but the azimuth angle range of (θ1+θ2+θ3) to 360 degrees may also be divided as appropriate.
[0024] Next, the observation target selection unit 122 compares the characteristics of the observation data obtained by the short pulse signal (P0N) with the characteristics of the observation data obtained by the long pulse signal (Q0N) for each predetermined azimuth angle, that is, for each of the sectors S1 to S3.
[0025] The characteristics of the observation data used as factors for comparison include, for example, the signal-to-noise ratio, reflection intensity, Doppler velocity, and velocity width, and the comparison is performed using at least one of these characteristics. The user of the weather radar 1 can select these characteristics appropriately depending on the observation purpose.
[0026] When the signal-to-noise ratio of the short pulse signal (P0N) and the long pulse signal (Q0N) is used as a comparison factor, for example, by selecting a signal with a higher signal-to-noise ratio, it is possible to select a signal with less noise influence and better sensitivity. Note that, since the long pulse signal (Q0N) usually tends to have a higher signal-to-noise ratio, if the signal-to-noise ratio is used as a comparison factor, it is expected that more sectors will be selected for observation of the long pulse signal (Q0N).
[0027] Furthermore, when the reflection intensities of the short pulse signal (P0N) and the long pulse signal (Q0N) are used as factors for comparison, for example, if there is a large difference in the reflection intensities of the two signals, there is a risk that the long pulse signal (Q0N) is leaking in. Therefore, by selecting the short pulse signal (P0N), the influence of the long pulse signal (Q0N) leaking in can be eliminated.
[0028] Furthermore, when the Doppler velocity of the short pulse signal (P0N) and the long pulse signal (Q0N) is used as a comparison factor, for example, if clutter is present, the Doppler velocity is likely to be zero. Therefore, by selecting a pulse signal with a finite Doppler velocity rather than a pulse signal with a Doppler velocity of zero, the effects of clutter can be eliminated.
[0029] Furthermore, when the speed width of the short pulse signal (P0N) and the long pulse signal (Q0N) is used as a comparison factor, highly accurate observation results can be obtained by, for example, selecting the pulse signal with a smaller speed width (i.e., smaller variation).
[0030] If there is no difference in superiority between the short pulse signal (P0N) and the long pulse signal (Q0N) when comparing the above characteristics of the observed data, it is possible to set in advance which signal to select. Also, if there is no difference in superiority between the short pulse signal (P0N) and the long pulse signal (Q0N) when comparing using one characteristic, it is possible to set it so that a comparison is made using another characteristic, and selection is made when a difference in superiority appears. Also, when comparing using two or more characteristics, it is possible to set in advance an order of priority as to which characteristic's comparison result should be given priority.
[0031] Based on the result of such comparison, the observation target selection unit 122 selects whether to observe the short pulse signal (P0N) or the long pulse signal (Q0N) for each predetermined azimuth angle, that is, for each of the sectors S1 to S3.
[0032] In the example shown in FIG. 3, a short pulse signal (P0N) is selected as the observation target for sector S1, and a long pulse signal (Q0N) is selected as the observation target for sectors S2 and S3. An example of such a result is when there is clutter in sector S1, causing interference of the long pulse signal (Q0N). In conventional examples, the observation target in the short-long boundary region 2 is often set to the long pulse signal (Q0N) in advance, so there is a high possibility that the long pulse signal (Q0N) will be selected as the observation target for all of sectors S1 to S3. On the other hand, the weather radar 1 according to this embodiment uses reflection intensity as a comparison factor, thereby selecting the short pulse signal (P0N) as the observation target for sector S1 and eliminating the influence of interference of the long pulse signal due to clutter. In the above case, a similar result can also be obtained by using Doppler velocity as a comparison factor.
[0033] The display unit 123 displays the observation data of the pulse signals selected by the observation target selection unit 122 for each predetermined azimuth angle, i.e., for each sector S1 to S3, as a radar image on the display screen of the weather radar 1. In the example shown in Fig. 3, an image obtained by combining an image based on the short pulse signal (P0N) of sector S1 and an image based on the long pulse signals (Q0N) of sectors S2 and S3 is displayed.
[0034] Next, the operation of signal processing in the short-long boundary area 2 in the weather radar 1 according to this embodiment will be described with reference to the flowchart of FIG.
[0035] The weather radar 1 alternately transmits a short pulse signal (P0N) and a long pulse signal (Q0N) from the radar transmitter 111, alternately receives reflected waves of the short pulse signal (P0N) and reflected waves of the long pulse signal (Q0N) at the radar receiver 112, performs signal processing on both pulse signals at the signal processor 121, and then outputs both pulse signals to the observation target selector 122 (Step 1). The observation target selector 122 divides the short / long boundary region 2 by a predetermined azimuth angle (Step 2), compares the characteristics of the observation data obtained by the short pulse signal (P0N) with the characteristics of the observation data obtained by the long pulse signal (Q0N) for each predetermined azimuth angle (Step 3), and, based on the results of the comparison, selects whether the short pulse signal (P0N) or the long pulse signal (Q0N) will be the observation target for each predetermined azimuth angle (Step 4).
[0036] As described above, according to the weather radar 1 of this embodiment, when performing signal processing on the short-long boundary region 2, which is an observation region using the short pulse signal (P0N) and an observation region using the long pulse signal (Q0N), it selects whether to observe the short pulse signal (P0N) or the long pulse signal (Q0N) for each azimuth angle, so that more appropriate observation data can be obtained and the accuracy of the radar device can be improved.In addition, since the pulse signal to be observed is selected by comparing the characteristics of the observation data, it is possible to obtain appropriate observation data depending on the observation purpose.
[0037] Furthermore, with the weather radar 1 according to this embodiment, it is only necessary to compare at least one of the S / N ratio, reflection intensity, Doppler velocity, and velocity width of the observation data, which simplifies the process of selecting the pulse signal to be observed. Furthermore, when comparing the S / N ratio of the observation data, it is possible to select a pulse signal with higher sensitivity. Furthermore, when comparing the reflection intensity of the observation data, it is possible to eliminate the influence of the long pulse signal (Q0N). Furthermore, when comparing the Doppler velocity of the observation data, it is possible to eliminate the influence of clutter. Furthermore, when comparing the velocity width of the observation data, it is possible to select a pulse signal that provides observation data with less variance.
[0038] (Embodiment 2) Next, a weather radar 1 according to a second embodiment of the present invention will be described. Note that the same components as those in the first embodiment will be denoted by the same reference numerals and detailed description thereof will be omitted.
[0039] The weather radar 1 of this embodiment differs from embodiment 1 in that it divides the short-long boundary region 2 at a predetermined azimuth angle and a predetermined distance, and compares the characteristics of the observation data and selects the signal to be observed for each predetermined azimuth angle and distance.
[0040] 5 is a schematic diagram showing a division manner of the short-long boundary region 2 and an example of selection of observation target signals in the weather radar 1 according to this embodiment. In the weather radar 1 according to this embodiment, the observation target selection unit 122 divides the short-long boundary region 2 by a predetermined azimuth angle, and then further divides it by a predetermined distance (distance from the radar device), as shown in FIG. 5. Specifically, the short-long boundary region 2 is divided into three parts (S1 to S3) by azimuth angles of 0 to θ1 degrees, azimuth angles of θ1 to (θ1+θ2) degrees, and azimuth angles of (θ1+θ2) to (θ1+θ2+θ3) degrees, and then further divided into four parts (a to d) by distances h2 to h4 from the radar device, for a total of 12 sectors. Specifically, these 12 sectors are sector S1a with an azimuth angle of 0 to θ1 degrees and a distance of h1 to h2, sector S1b with an azimuth angle of 0 to θ1 degrees and a distance of h2 to h3, sector S1c with an azimuth angle of 0 to θ1 degrees and a distance of h3 to h4, sector S1d with an azimuth angle of 0 to θ1 degrees and a distance of h4 to h5, sector S2a with an azimuth angle of θ1 to (θ1+θ2) degrees and a distance of h1 to h2, sector S2b with an azimuth angle of θ1 to (θ1+θ2) degrees and a distance of h2 to h3, and sector S3 with an azimuth angle of θ1 to (θ1+θ2) degrees and a distance of h3 to h4. sector S2c with azimuth angles θ1 to (θ1+θ2) degrees and distance h4 to h5, sector S2d with azimuth angles (θ1+θ2) to (θ1+θ2+θ3) degrees and distance h1 to h2, sector S3b with azimuth angles (θ1+θ2) to (θ1+θ2+θ3) degrees and distance h2 to h3, sector S3c with azimuth angles (θ1+θ2) to (θ1+θ2+θ3) degrees and distance h3 to h4, and sector S3d with azimuth angles (θ1+θ2) to (θ1+θ2+θ3) degrees and distance h4 to h5. Note that central angles θ1, θ2, and θ3 may be the same or different. Furthermore, the distances (h2-h1), (h3-h2), (h4-h3), and (h5-h4) may be the same or different. For the sake of explanation, Fig. 5 divides only the azimuth angle range of 0 to (θ1+θ2+θ3) degrees, but the azimuth angle range of (θ1+θ2+θ3) to 360 degrees may also be divided as appropriate.
[0041] Next, the observation target selection unit 122 compares the characteristics of the observation data based on the short pulse signal (P0N) with the characteristics of the observation data based on the long pulse signal (Q0N) for each predetermined azimuth angle and predetermined distance, i.e., for each sector S1a to S1d, S2a to S2d, and S3a to S3d, and based on the results of the comparison, selects whether to observe the short pulse signal (P0N) or the long pulse signal (Q0N) for each predetermined azimuth angle and predetermined distance, i.e., for each sector S1a to S1d, S2a to S2d, and S3a to S3d. An example of the result of this observation target selection is shown in FIG. 5. Note that the characteristics of the observation data that are factors in the comparison are the same as those in the first embodiment, so details of the comparison and selection will be omitted.
[0042] Next, the operation of signal processing in the short-long boundary area 2 in the weather radar 1 according to this embodiment will be described with reference to the flowchart of FIG.
[0043] The weather radar 1 alternately transmits a short pulse signal (P0N) and a long pulse signal (Q0N) from the radar transmitter 111, alternately receives reflected waves of the short pulse signal (P0N) and reflected waves of the long pulse signal (Q0N) at the radar receiver 112, performs signal processing on both pulse signals at the signal processor 121, and then outputs both pulse signals to the observation target selector 122 (Step 1). The observation target selector 122 divides the short / long boundary region 2 at predetermined azimuth angles and predetermined distances (Step 2a), compares the characteristics of the observation data obtained by the short pulse signal (P0N) with the characteristics of the observation data obtained by the long pulse signal (Q0N) for each predetermined azimuth angle and predetermined distance (Step 3a), and, based on the results of the comparison, selects whether the short pulse signal (P0N) or the long pulse signal (Q0N) will be the observation target for each predetermined azimuth angle and predetermined distance (Step 4a).
[0044] As described above, the weather radar 1 according to this embodiment divides the short-long boundary region 2 not only by azimuth angle but also by distance (distance from the radar device), and selects pulse signals to be observed for each of the more subdivided regions, thereby making it possible to obtain more appropriate observation data and further improve the accuracy of the radar device.
[0045] Although the embodiments of the present invention have been described above, the specific configuration is not limited to the above embodiments, and design changes within the scope of the present invention are also included in the present invention. For example, in the above embodiments, the present invention has been described using a weather radar as an example, but the present invention can also be applied to other types of radar devices, such as aircraft radar. Furthermore, in the above embodiments, it has been described that the observation target selection unit performs the process of selecting the observation target in the short-long boundary region, but it is also possible for the signal processing unit or the display unit to function as the observation target selection unit and perform this process. [Explanation of symbols]
[0046] 1. Weather radar (radar device) 11 Antenna section 111 Radar transmitter 112 Radar receiver 113 Radar drive unit 12 Processing control section 121 Signal Processing Unit 122 Observation target selection unit (observation target selection means) 123 Display section 124 Control Unit 2 Short-length boundary region P0N Short pulse signal Q0N Long pulse signal
Claims
1. A radar device that alternately transmits a short pulse signal and a long pulse signal having a pulse width longer than that of the short pulse signal, An observation target selection means is provided, The observation target selection means When performing signal processing on a short-long boundary region which is an observation region using the short pulse signal and an observation region using the long pulse signal, the short-long boundary region is divided at a predetermined azimuth angle; comparing characteristics of the observation data obtained by the short pulse signal with characteristics of the observation data obtained by the long pulse signal for each of the predetermined azimuth angles; selecting, for each of the predetermined azimuth angles, whether to observe the short pulse signal or the long pulse signal based on the result of the comparison; A radar device characterized by:
2. The observation target selection means Dividing the short and long boundary regions by a predetermined azimuth angle and a predetermined distance; performing the comparison for each of the predetermined azimuth angles and the predetermined distances; performing the selection for each of the predetermined azimuth angles and the predetermined distances based on the results of the comparison; 2. The radar device according to claim 1, wherein:
3. The characteristics of the observation data are at least one of an S / N ratio, a reflection intensity, a Doppler velocity, and a velocity width.
3. The radar device according to claim 1, wherein the radar device comprises: a first detecting means;
4. 1. A method for selecting an observation target in a radar device that alternately transmits a short pulse signal and a long pulse signal having a pulse width longer than that of the short pulse signal, comprising: a step of dividing the short-to-long boundary region at a predetermined azimuth angle when performing signal processing on the short-to-long boundary region, which is an observation region using the short pulse signal and also an observation region using the long pulse signal; comparing characteristics of observation data obtained by the short pulse signal with characteristics of observation data obtained by the long pulse signal for each of the predetermined azimuth angles; and selecting, based on a result of the comparison, whether the short pulse signal or the long pulse signal is to be observed for each of the predetermined azimuth angles.
10. A method for selecting an observation target for a radar device, comprising: