JP5591544B2 - Radar apparatus and radar signal processing method - Google Patents

Description

  The present invention relates to a radar apparatus and a radar signal processing method.

  A search radar that searches for a target adjusts a PRI (pulse repetition interval), which is one of the radar parameters, so as to satisfy a required coverage in a required target RCS (effective reflection area; radar cross section). In a search radar using a phased array antenna, it is required to improve tracking performance (tracking rate) in order to reliably detect a target.

  For example, Patent Document 1 describes an antenna device that improves the data rate of a target search. In this antenna device, the aperture of the array antenna is divided in the elevation direction, and the search area is also divided corresponding to the division. A reception beam is formed for each of the divided scanning coverage areas and a target is detected. The search is done so that there are no duplicates.

JP 2004-279147 A (paragraph 0036)

  However, in order to improve the search data rate by the technique described in Patent Document 1, it is necessary to increase the transmission aperture or the reception aperture (increase the transmission or reception module). For this reason, it is necessary to review the system scale and implementation is not easy.

  In addition, if searches for different distances are continuously performed in the same direction, even if a target is detected in both areas near the boundary of the search area, the search time difference between the areas is extremely short. For this reason, it does not contribute to the improvement of the tracking rate.

  The present invention has been made in view of the above problems, and an object thereof is to provide a radar apparatus and a radar signal processing method with improved tracking performance.

  A radar apparatus according to an embodiment of the present invention searches for a predetermined search area and detects a target based on radar transmission / reception means for transmitting and receiving radar signals and reception signals received by the radar transmission / reception means. Detection means; tracking means for performing tracking processing for tracking the target detected by the target detection means; and search control means for controlling search of the search area by the detection means, wherein the search area is azimuthally oriented. Each of the plurality of areas is further divided in the distance direction to generate a plurality of divided areas so that a part of the adjacent divided areas overlaps, and the divided areas are divided in the same direction. Search control means for setting the search order of the plurality of divided regions by the detection means so that a time difference occurs in the search between them.

  A radar signal processing method according to an embodiment of the present invention is a radar signal processing method for processing a radar signal in a radar apparatus including radar transmission / reception means for transmitting and receiving radar signals, the radar transmission / reception means. A step of searching for a predetermined search region based on the received signal received to detect a target, a step of performing a tracking process for tracking the target, and a step of controlling the search of the search region. The search area is divided into a plurality of areas in the azimuth direction, each of the plurality of areas is further divided in the distance direction, and a plurality of divided areas are generated so that a part of the adjacent divided areas overlaps, A step of setting a search order of the plurality of divided regions so that a time difference occurs in the search between the divided regions with respect to the same direction;

  According to the present invention, it is possible to provide a radar apparatus and a radar signal processing method with improved tracking performance.

1 is a block diagram showing a configuration of a radar apparatus according to an embodiment of the present invention. The figure which shows roughly about the detection performed by dividing the search area | region W into the distance direction. The figure which shows an example of the search order at the time of dividing | segmenting a search area | region as shown in FIG. The figure which shows roughly about the detection performed by making the search area W overlap in the distance direction and dividing into two. The figure which shows an example of the search order at the time of dividing and overlapping a search area | region as shown in FIG. The figure which shows an example of the search order which concerns on this embodiment at the time of dividing a search area | region as it overlaps as shown in FIG. The figure which shows an example of the result of the target search performed according to the search order set as shown in FIG. The figure which shows an example of the result of the target detection performed according to the search order set as shown in FIG. The figure which shows the relationship between PRI, RCS, and detection distance.

  Hereinafter, an embodiment of a radar apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a radar apparatus according to an embodiment of the present invention. As shown in FIG. 1, the radar apparatus includes a radar control unit 10, an antenna unit 20, a scanning control unit 30, a target detection unit 40, and a tracking processing unit 50.

  The radar control unit 10 controls the operation of the entire radar apparatus. Specifically, the radar apparatus 10 manages a beam schedule, for example, and controls a target search order and a PRI (pulse repetition interval).

  The antenna unit 20 is configured as a phased array antenna, and includes a transmission unit 21, a power distribution combiner 22, a plurality of transmission / reception modules 23-1 to 23-n, a plurality of antenna elements 24-1 to 24-n, and a reception unit 25. It comprises.

  At the time of transmitting the radar signal, the power distribution synthesizer 22 distributes the transmission signal transmitted from the transmission unit 21 and supplies it to the transmission / reception modules 23-1 to 23-n.

  The transmission / reception modules 23-1 to 23-n adjust the phase and amplitude of the corresponding antenna elements 24-1 to 24-n and perform signal amplification of the transmission signals. This transmission signal is radiated into the space from the antenna measures 24-1 to 24-n.

  At the time of signal reception, low noise amplification and phase control are performed on the reception signals received by the antenna elements 24-1 to 24-n by the corresponding transmission / reception modules 23-1 to 23-n.

  The receiving unit 25 performs power combining of the reception signals transmitted from the transmission / reception modules 23-1 to 23-n. The receiving unit 25 performs frequency conversion to an intermediate frequency (IF), analog / digital conversion, and quadrature detection on the received signal. A complex type I (In-phase) signal and Q (Quadrature) signal are generated by quadrature detection, and the generated I signal and Q signal are sent to the target detection unit 40.

  The scanning control unit 30 transmits a control signal corresponding to the beam scanning angle to the transmission / reception modules 23-1 to 23-n. The transmission / reception modules 23-1 to 23-n set the phase and amplitude of the corresponding antenna elements 24-1 to 24-n according to the control signal.

  The target detection unit 40 forms a desired reception beam based on the I signal and the Q signal output from the reception unit 25. The target detection unit 40 performs target detection processing for searching for and detecting a target from the formed reception beam. The target information representing the detected target is sent to the tracking processing unit 50.

  The tracking processing unit 50 performs target correlation processing and tracking processing based on the target information sent from the target detection unit 40.

  Next, the operation of the radar apparatus configured as described above will be described.

The radar control unit 10 manages beam forming timing and a search area for the target detection unit 40 to perform target detection processing. The maximum detection distance of a normal radar is expressed by the following equation (1).

  As shown in the equation (1), the detection at a long distance becomes possible as the value σ of the target RCS (effective reflection area; radar cross section) is larger. For this reason, the radar control unit 10 adjusts the PRI according to the target RCS to be processed. That is, the search distance is controlled by the radar controller 10 changing the PRI.

  FIG. 2 is a diagram schematically showing detection performed by dividing the search area W into two in the distance direction. In the example shown in FIG. 2, the search area for one azimuth θ is divided into a search area A on the short distance side and a search area B on the long distance side. In this example, as in the prior art, there is no overlapping area between the search area A and the search area B.

  FIG. 3 is a diagram showing an example of the search order when the search area is divided as shown in FIG. In the example shown in FIG. 3, the search area W is divided into N areas (−X to X) in the azimuth direction. In each direction, the search area is divided into a search area A on the short distance side and a search area B on the long distance side.

  In the example shown in FIG. 3, the search order of the search area A in the direction θ = −X is set to the first, and the search order of the search area B is set to the second. Similarly, in each direction, after searching for the search area A on the short distance side, the search for the search area B on the long distance side is performed. Search time T is required to complete all search areas. That is, for each of the divided search areas, the search is performed with the period T. For this reason, the tracking rate cannot be improved for each region.

  FIG. 4 is a diagram schematically showing detection performed by dividing the search area W into two in the distance direction. In the example shown in FIG. 4, the search area for one direction is divided into a search area (division area) A on the short distance side and a search area (division area) B on the long distance side. Part of B is duplicated.

  FIG. 5 is a diagram showing an example of the search order when the search areas are divided and overlapped as shown in FIG. In the example shown in FIG. 5, the search area W is divided into N areas (−X to X) in the azimuth direction. In each direction, the search area is divided into a search area A on the short distance side and a search area B on the long distance side. A part of the divided area A on the near side and a part of the divided area B on the far side overlap each other.

In the example shown in FIG. 5, the search order of the search area A in the direction θ = −X is set to the first, and the search order of the search area B is set to the second. Similarly, in each direction, after searching the search area A on the short distance side, searching for the search area B on the long distance side is completed. Search time T is required to finish all the search areas. Is done. At this time, the search is performed twice during the period T for the overlapping regions in each direction. However, since the timings of these two searches are close, there is almost no difference in the detection results. For this reason, it does not contribute to the improvement of the tracking rate.

  Therefore, in this embodiment, the search area and search order are set as follows to improve the tracking rate.

  FIG. 6 is a diagram illustrating an example of a search order according to the present embodiment when the search areas are divided and overlapped as shown in FIG. In the example shown in FIG. 6, the search area W is divided into N areas (−X to X) in the azimuth direction. In each direction, the search area is divided into a search area (division area) A on the short distance side and a search area (division area) B on the long distance side. A part of the divided area A on the near side and a part of the divided area B on the far side overlap each other.

  In the example shown in FIG. 6, the search order of the search area A in the direction θ = −X is set to the first, and this search area A is searched first. In FIG. 6, the search order of the search area A at θ = −X + 1 on the right side is set to the second position, and this search area A is searched second. Thereafter, similarly, the search area A on the short distance side is sequentially searched in each direction.

  Then, after the search of the search area A is completed, the search area B in the direction θ = −X is searched. Subsequently, in FIG. 6, the search area B in the right adjacent θ = −X + 1 is searched. Thereafter, similarly, the long-distance search area B is sequentially searched in each direction. Such a search order is set by the radar control unit 10.

  A search time T is required in the same manner as in the example of FIG. 5 until all search areas are completed. Accordingly, the search time T / 2 is required for searching all the search areas A on the short distance side (inner side), and the search time T / 2 is required for searching all the search areas B on the far distance side (outer side). For this reason, in the overlapping area in each azimuth, the search is performed with the period T / 2, and even in the same azimuth, a time difference is generated by T / 2 in the search timing. As a result, a difference occurs between search results of the same direction, and the search result of the overlapping area becomes meaningful, and the tracking rate in the overlapping area can be improved.

  Next, the improvement of the tracking rate by dividing the search area and controlling the search order will be described.

  FIG. 7 is a diagram showing an example of the result of the target search performed according to the search order set as shown in FIG. In the example shown in FIG. 7, the target a, the target b, and the target c exist in the search area W. When there is no overlap between the search area A on the short distance side and the search area B on the long distance side, the search is performed in the period T for each of the divided search areas. For this reason, all of the target a, the target b, and the target c are detected once during the search time T. Further, the tracking process is performed at the tracking interval T.

  FIG. 8 is a diagram showing an example of the result of target detection performed according to the search order set as shown in FIG. Also in the example illustrated in FIG. 8, the target a, the target b, and the target c exist in the search area W. In this case, after all the search areas A (inside the search area W) have been searched, all the search areas B (outside the search area W) are searched, and the search of the search area A is performed in one direction. There is a sufficient time interval between the search of the search area B. Therefore, when there is an overlap between the search area A on the short distance side and the search area B on the long distance side, the search is performed in the overlap area in the cycle T / 2.

  For this reason, the target b and the target c in the overlapping region are detected twice during the search time T. In the overlapping area, the tracking process is performed at the tracking interval T / 2. For this reason, it can be seen that the tracking rate is improved and the tracking performance is high for the target in the overlapping region.

  On the other hand, the target a existing outside the overlapping region is detected once during the search time T as in the case of FIG. 7, and the tracking process is performed at the tracking interval T. However, the tracking rate is not inferior to the case of FIG.

  As described above, according to the radar apparatus according to the present embodiment, the tracking rate can be improved by dividing the search area in an overlapping manner and appropriately setting the search order. In this radar apparatus, the laser parameter (PRI) is changed by the radar control unit 10 and the search area dividing method and search order are adjusted. This improves the tracking performance.

  In other words, by dividing the search area in the distance direction and setting the search time interval between the areas divided in the same direction sufficiently large, early detection and increased detection opportunities (tracking) for the target of the overlapping area Rate), and tracking performance can be improved.

  Note that by adjusting PRI, which is one of the radar parameters, if the target RCS is large, the detection distance can be extended and the overlapping region can be extended.

  FIG. 9 is a diagram illustrating the relationship between PRI, RCS, and detection distance.

As shown on the left side in FIG. 9, the maximum detection distance when PRI = Y [μs] is y [km]. At this time, as shown in the figure, the maximum detection distance at RCS = A [m ² ] is a [km] (a <y), and the maximum detection distance at RCS = B [m ² ] is b [km] ( b <y) is uniquely determined. That is, the maximum detection distance can be extended by the target RCS by controlling the PRI. By extending the detection distance, it is possible to quickly detect a long-distance target.

  Therefore, a desired detection distance can be realized by setting the PRI according to the target RCS.

  As described above, the radar apparatus according to the present embodiment can improve the tracking performance without changing the system scale.

  In the above-described embodiment, a part of the search area A and the search area B are overlapped. The overlapping areas may be set so as to include more targets as shown in FIG. If an area where the target is likely to exist is known, the search area is divided so that the area is included in the overlapping portion.

  In the above-described embodiment, as shown in FIG. 6, the search of the search area A on the short distance side is sequentially performed in the order of the orientation, and then the search of the search area B on the long distance side is sequentially performed in the order of the orientation. However, the search of the search area B on the long distance side may be sequentially performed in the order of the azimuth, and then the search of the search area A on the short distance side may be sequentially performed in the order of the azimuth. Further, the search order is not limited to the order of the directions. If there is a sufficient time difference (for example, about one half of the search time T) between the search of the search range A and the search of the search range B in the same direction, the radar control unit 10 determines what search order. It may be set.

  A sufficient time difference between the search of the search range A and the search of the search range B may be determined according to the moving speed of the target. In the search results of the search range A and the search range B, it suffices if a difference occurs in the overlapping portion, a short time difference may be set for a target having a high moving speed, and a long time difference may be set for a target having a low moving speed. .

  Further, the search order shown in FIG. 3 (no duplication), the search order shown in FIG. 5 (with duplication), and the search order shown in FIG. 6 (with duplication and a search time difference in one direction) may be used. Good. In the operation sequence of FIG. 3 and the operation sequence of FIG. 5, since the search is performed for each direction, the processing result can be illustrated in an easy-to-understand manner. Therefore, the search order shown in FIG. 6 may be used when a search is normally performed according to the search order shown in FIG. 3 or 5 and tracking with higher accuracy is required.

  In the above-described embodiment, the search area is divided into two in the distance direction for one azimuth, but the search area may be divided into two or more divided areas.

  In the above-described embodiment, the antenna unit 20 is configured as an array antenna. However, the present invention can also be applied to a radar apparatus that uses another type of antenna such as a rotating radar.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention when it is practiced. Further, each of the embodiments includes inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in one embodiment or the constituent elements shown in some embodiments are combined, they are described in the column of the problem to be solved by the invention. In the case where the problems described above can be solved and the effects described in the “Effects of the Invention” can be obtained, a configuration in which these constituent requirements are deleted or combined can be extracted as an invention.

  DESCRIPTION OF SYMBOLS 10 ... Radar apparatus, 20 ... Antenna part, 21 ... Transmission part, 22 ... Power distribution synthesizer, 23-1 to 23-n ... Transmission / reception module, 24-1 to 24-n ... Antenna element, 25 ... Reception part, 30 ... Scanning control unit, 40 ... target detection unit, 50 ... tracking processing unit.

Claims (4)

Radar transmitting and receiving means for transmitting and receiving radar signals;
Based on the received signal received by the radar transmission / reception means, a detection means for searching a predetermined search area and detecting a target;
Tracking means for performing tracking processing for tracking the target detected by the detection means;
Search control means for controlling search of the search area by the detection means,
Dividing the search area into a plurality of areas in the azimuth direction;
Each of the plurality of regions is further divided in the distance direction to generate a plurality of divided regions so that a part of the adjacent divided regions overlap,
For the same direction, search control means for setting the search order of the plurality of divided areas by the detection means so that a time difference according to the moving speed of the target occurs in the search between the divided areas,
A radar apparatus comprising:   The radar apparatus according to claim 1, wherein the search control unit divides each of the plurality of regions in the distance direction by controlling an effective reflection area of the radar transmission / reception unit.   The radar apparatus according to claim 1, wherein the search control unit divides each of the plurality of regions in the distance direction by controlling a pulse repetition period of the radar transmission / reception unit. A radar signal processing method for processing a radar signal in a radar apparatus comprising a radar transmitting / receiving means for transmitting and receiving a radar signal,
Detecting a target by searching a predetermined search area based on the received signal received by the radar transmitting and receiving means;
Performing a tracking process for tracking the target;
Controlling the search of the search area, comprising:
Dividing the search area into a plurality of areas in the azimuth direction;
Each of the plurality of regions is further divided in the distance direction to generate a plurality of divided regions so that a part of the adjacent divided regions overlap,
For the same azimuth, setting the search order of the plurality of divided regions so that a time difference according to the moving speed of the target occurs in the search between the divided regions;
A radar signal processing method comprising:

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