JP2012198243A - Apparatus for detecting and displaying target - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately and automatically detect a sea surface reflection region and automatically select and execute different scan correlation processing according to the inside of the sea surface reflection region and the outside of the sea surface reflection region respectively.SOLUTION: A sea surface reflection region detection part 10 detects whether pixels corresponding to echo data are instable pixels or not according to the echo data. The sea surface reflection region detection part 10 extends a temporal instable state of the instable pixels and enlarges planar regions of the instable pixels to determine sea surface reflection region. A continuity detection part 9 detects planar continuity of the pixels corresponding to the echo data. A W data generating part 6 uses scan correlation processing calculation made of a plurality of types of coefficients set based on inside and outside the sea surface reflection region and presence or absence of continuity to calculate scan correlation processing result data of this time from the echo data of this time and the scan correlation processing result data of the last time stored in an image memory 7 and updates and stores the scan correlation processing result data of this time in the image memory 7.

Description

  The present invention relates to a radar apparatus and a similar apparatus for converting received data of a polar coordinate system into image data of an orthogonal coordinate system and displaying the image data. In particular, the present invention relates to an apparatus for detecting and displaying a target that suppresses the influence of sea surface reflection and displays a target that is difficult to identify such as a distant target.

  Conventionally, in a radar apparatus that detects targets in all directions of a ship, a received signal in a polar coordinate system is acquired while rotating a radar antenna at a predetermined period. The radar apparatus converts the received signal in the polar coordinate system into image data in the orthogonal coordinate system, writes the image data in the image memory, and reads out each image data stored in the image memory at a predetermined timing. Then, the display unit of the radar apparatus displays the light intensity and the color in accordance with the data level of the read image data.

In such a radar apparatus, various processes are executed in order to facilitate detection of a target that is being reflected from the sea surface and detection of a target that has a low detection frequency.
For example, in Patent Document 1, scan correlation processing with different specifications is selected for a range within the distance and a range outside the distance on the basis of the distance from the antenna and the unnecessary wave intensity. Here, the scan correlation process is a process for determining the display data of this time based on the degree of correlation between the current data and past data at the same position as the current data.

  Moreover, in patent document 2, while performing a correlation process and an afterimage process with respect to a received signal, the level of an unnecessary signal is detected. When an area where the level of the unnecessary signal is greater than or equal to a predetermined value is detected, the result of correlation processing is displayed in the area, and when an area where the level of the unnecessary signal is less than the predetermined value is detected, the result of afterimage processing is displayed in the area.

In addition, some conventional radar apparatuses include scan correlation processes with different specifications, and switch a plurality of scan correlation processes according to an operation input from a user.
Japanese Patent No. 3680265 JP 2002-243842 A

  However, in an apparatus that accepts an operation input from the user, the scan correlation process is selected by an operation from the user. Therefore, in order to select an effective scan correlation process, the user's operation skill level is required and the operation is inappropriate. In this case, the target identification status may worsen. Further, since appropriate scan correlation processing is different between the inside and outside of the region where the sea surface reflection is likely to occur, the user must perform the operation in consideration of this difference, and the operation becomes more difficult.

  In addition, in the case of afterimage processing, unnecessary signals input such as white noise and radar interference become stronger when sensitivity is increased by observing weak echoes in the distance, and unnecessary signals are cumulatively added if sensitivity is increased too much. The screen is filled with noise, making it difficult to identify the target. In such a case, it is necessary to finely adjust the sensitivity in order to obtain an appropriate image.

  Accordingly, an object of the present invention is to automatically detect a sea surface reflection area appropriately, automatically select and execute different scan correlation processing depending on the inside and outside of the sea surface reflection area, and perform white noise etc. It is an object of the present invention to provide a radar device and a similar device that are easy to view and can be easily adjusted without accumulating unnecessary signals.

  The present invention relates to an apparatus for detecting and displaying a target provided with received data acquisition means, image data generation storage means, and display means. The reception data acquisition means sequentially acquires the reception data in the polar coordinate system obtained by rotating the sweep. The image data generating and storing means converts the received data in the polar coordinate system into image data in the orthogonal coordinate system, and updates each image data constituting the entire screen every rotation of the sweep according to the received data. Image data is sequentially generated and stored. The display means sequentially reads and displays the image data stored in the image data generation and storage means. Furthermore, the radar apparatus and similar apparatus of the present invention are provided with sea surface reflection area detecting means. The sea surface reflection area detecting means detects whether or not the received data is equal to or greater than a preset threshold value, and based on the transition of detection results for the past several scans including the current time corresponding to the received data on which the threshold value detection has been performed. The degree of instability is detected, and the sea surface reflection region is determined based on the degree of instability. The sea surface reflection area detection means is predetermined for a pixel corresponding to received data that is a determination criterion of the sea surface reflection area and a pixel set by holding the predetermined scan described above in a distance direction and an azimuth direction including the pixel. A portion having a range spread is set as an enlarged sea surface reflection region. Based on the determined sea surface reflection area and the enlarged sea surface reflection area, the image data generation and storage means is configured to perform an averaging process or an integration process based on the current data and the past data in the sea surface reflection area and the enlarged sea surface reflection area. Data generation processing is performed, and image data generation processing for emphasizing the current data is performed outside the sea surface reflection area and the enlarged sea surface reflection area.

  In this configuration, it is detected whether or not the received data is equal to or greater than a preset threshold value, and the detection status from the detection result of the current reception data and the detection results for the past several scans at the same position as the current reception data Get the transition of. Here, at the position where the sea surface reflection exists, there is a possibility that the times when the received data above the threshold value is detected and the times when the received data below the threshold value are detected are irregularly changed due to the influence of the sea surface reflection. growing. Therefore, it is possible to detect whether or not the region is a sea surface reflection region by acquiring such a transition of the detection state. After setting the sea surface reflection area in this way, the image data generation and storage means performs different image data processing in the sea surface reflection area and outside the sea surface reflection area. Here, scan correlation processing is executed as image data processing.

  Specifically, in the sea surface reflection region, received data that is detected suddenly and temporarily by performing scan correlation processing in which the result depends on past data rather than current data by averaging processing and integration processing, In other words, the reception data due to the sea surface reflection is suppressed from being characteristically displayed on the display screen. On the contrary, continuously detected reception data, that is, reception data based on actual targets, is characteristically displayed on the display screen.

  On the other hand, outside the sea surface reflection area, by performing scan correlation processing that emphasizes the current data, targets that appear at the same pixel position, such as targets with low detection frequency or targets that move at high speed, are low. However, the received data is reflected in the display and is displayed characteristically on the display screen.

  In this configuration, an enlarged sea surface reflection region is set by enlarging the distance direction and the azimuth direction with respect to the reception data of the target from which the sea surface reflection region is detected. This is set based on the high possibility that the sea surface is unstable around the position detected as the sea surface reflection region. For example, even if it is detected that it is not the sea surface reflection area in the very vicinity of the position detected as the sea surface reflection area (adjacent pixel data position, etc.), it is highly likely that it was not detected by chance. Set in the sea surface reflection area. Thereby, the sea surface reflection region can be set more stably and reliably.

  The apparatus for detecting and displaying the target of the present invention further includes continuity detecting means. The continuity detection means includes reception data to be determined, sets a region within a predetermined range extending in the distance direction and the azimuth direction as a determination reference region, and sets a plurality of reception data in the determination reference region to a number equal to or greater than a threshold value. Detect continuity based on. Then, the image data generation and storage means performs the image data generation process by adjusting the specific gravity of the reflection of the current data based on the continuity.

  In this configuration, the specific gravity of the current data is determined based not on temporal continuity at the position of the reception data to be determined, but on planar continuity near the position of the reception data to be determined. If this is an echo due to its own transmission, there is a spread in the azimuth direction by the antenna beam width, so the planar continuity of the received data group above the threshold is high, such as radar interference or white noise that is input asynchronously to the transmission. Then, it is set based on the low planar continuity of the received data group equal to or greater than the threshold.

  Specifically, if the continuity is high, the specific gravity with respect to the display of the current data is increased, and control is performed so that the data is displayed more characteristically. If the continuity is low, the specific gravity for the display of the current data is suppressed low. As a result, the actual target is displayed characteristically and the interference or the like is not characteristically displayed, and these can be identified more clearly.

  Further, when the continuity detecting means of the apparatus for detecting and displaying the target of the present invention detects that the detected number is equal to or greater than a preset continuity detection threshold, the received data to be determined has continuity. Judge. The image data generation and storage unit adjusts the specific gravity of reflection according to the presence or absence of continuity.

  In this configuration, the adjustment of the specific gravity by continuity is set by two values of presence / absence of continuity. Thereby, since it is expressed only by the binary value of presence / absence of continuity, processing by continuity is simplified.

  Further, the image data generation and storage means of the apparatus for detecting and displaying the target of the present invention executes the adjustment of the reflection specific gravity based on the continuity only when it is outside the sea surface reflection area and the expanded sea surface reflection area. .

  In this configuration, since the above-described enhancement processing is executed outside the sea surface reflection region where there is no sea surface reflection, discrimination by continuity becomes more effective, and radar interference and white noise can be suppressed.

  According to the present invention, the sea level instability can be detected based on the current received data and past data at the same position, and the sea surface reflection area can be automatically set based on the sea level instability. And by selecting scan correlation processing according to each state inside and outside this sea surface reflection area, the influence of sea surface reflection is suppressed, and targets that are difficult to display such as targets with low detection frequency are reliably displayed. can do. Thereby, it is possible to realize an apparatus that detects and displays a target that can appropriately suppress the influence even by partial or local sea surface reflection and can reliably display the target. In addition, by using the concept of continuity, it is possible to emphasize and display echoes of targets with low detection frequency in the same manner as these while suppressing display of radar interference and white noise.

  A radar apparatus according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a radar apparatus will be described as an example, but the present embodiment can be applied to any apparatus that detects and displays a target such as sonar.

FIG. 1 is a block diagram showing the main configuration of the radar apparatus of the present embodiment.
The radar antenna 1 of the radar apparatus according to the present embodiment radiates a pulsed radio wave with a transmission / reception period different from the rotation period while rotating on a horizontal plane at a predetermined rotation period, and also reflects a reflected wave from a target around the apparatus. Is received in the polar coordinate system. The radar antenna 1 outputs a reception signal to the reception unit 2 and outputs sweep angle data to the drawing address generation unit 5.

  The receiving unit 2 detects and amplifies the received signal from the radar antenna 1 and outputs the amplified signal to the AD converting unit 3. The AD conversion unit 3 converts the analog reception signal into digital data (echo data) composed of a plurality of bits.

  The sweep memory 4 stores the digitally converted echo data for one sweep in real time, and the echo data Xn for one sweep is generated as W data until the echo data obtained by the next transmission is written again. Output to the unit 6, the continuity detection unit 9, and the behavior data generation unit 11.

  The drawing address generator 5 uses the center of the sweep rotation as the start address, and responds from the antenna angle θ with reference to a predetermined direction (for example, the bow direction) and the read position r of the sweep memory 4 from the center to the periphery. Addresses for designating the pixels of the image memory 7, the behavior data memory 711, and the unstable state holding memory 713 arranged in the orthogonal coordinate system are created. Specifically, the drawing address generation unit 5 is configured by hardware that realizes the following equation.

X = Xs + r · sin θ
Y = Ys + r · cos θ
However, X and Y are addresses that specify pixels of the image memory 7, behavior data memory 711, and unstable state holding memory 713, Xs and Ys are the center addresses of sweeps, and r is the distance from the center, θ is the angle of the sweep (antenna).

  The sea surface reflection region detection unit 10 includes a behavior data generation unit 11, an unstable pixel detection unit 12, an unstable state holding data generation unit 13, and a sea surface reflection region determination unit 14.

  The behavior data generation unit 11 determines whether or not the current echo data Xn input from the sweep memory 4 is equal to or greater than a preset detection threshold. As the detection threshold, for example, a value obtained by adding a predetermined offset to the detected white noise level is used. The behavior data generating unit 11 generates behavior data consisting of “1” if the current echo data Xn is equal to or greater than the detection threshold, and behaviors consisting of “0” if the current echo data Xn is less than the detection threshold. Generate data.

  The behavior data memory 711 is a storage medium that stores behavior data for each pixel set by an orthogonal coordinate system address, similarly to the image memory 7 and the unstable state holding memory 713 described later. Addresses are set in the behavior data memory 711, the image memory 7, and the unstable state holding memory 713 so that the pixel addresses correspond to each other. The behavior data memory 711 is assigned with a plurality of bits for each pixel, and has a capacity for storing behavior data for a plurality of scans in time series from this time. At this time, the behavior data is stored while shifting to the upper bits step by step from the LSB to the MSB in time series.

  The behavior data generation unit 11 generates the current behavior data in synchronization with the conversion processing from the polar coordinate system to the orthogonal coordinate system, and from the behavior data memory 711, a plurality of past data at the pixel addresses corresponding to the current behavior data. A multi-bit behavior data string Pn-1 consisting of scan behavior data is read. The behavior data generating unit 11 shifts each behavior data of the read behavior data sequence Pn-1 by one step to the upper side, and outputs the current behavior data sequence Pn with the least significant bit as the current behavior data. For example, when an 8-bit configuration is set for each pixel, the behavior data of bit 0 to bit 6 of the read behavior data string Pn−1 is shifted from bit 1 to bit 7 respectively, the behavior data of bit 7 is discarded, and bit 0 This time behavior data is assigned. Thereby, behavior data for the past 8 scans including this time are stored.

  The current behavior data string Pn output from the behavior data generation unit 11 in this way is updated and stored in the corresponding pixel address of the behavior data memory 711 and also input to the unstable pixel detection unit 12.

  The unstable pixel detection unit 12 acquires the behavior data string Pn from the behavior data generation unit 11 and calculates the number of state changes between adjacent bits of the behavior data string Pn as the degree of instability. That is, the number of times of changing from “1” to “0” or from “0” to “1” is detected between adjacent bits (for example, bit 0 and bit 1 and bit 6 and bit 7).

For example, FIG. 2 is a diagram illustrating a relationship among the behavior data string Pn, the degree of instability, and the unstable state detection data.
As shown in the upper part of FIG. 2, when each behavior data in the behavior data string Pn alternates between “1” and “0” every scan, the state change occurs 7 times in 8 bits. Is calculated as “7”. As shown in the lower part of FIG. 2, when each behavior data in the behavior data string Pn changes only once from “0” to “1”, the state change occurs once in 8 bits. The stability is calculated as “1”.

  Thereby, the unstable pixel detection unit 12 detects how the echo data changes with respect to the detection threshold for the past plural scans including the current time for the pixel to be determined. For example, echo data that is equal to or greater than the detection threshold is acquired continuously and stably, echo data that is less than the detection threshold is acquired stably and continuously, or echo data that is equal to or greater than the detection threshold and less than the detection threshold It is detected whether the echo data is acquired in an irregular order.

  When calculating the degree of instability, the unstable pixel detection unit 12 generates an unstable state detection data Qn by comparing with a preset unstable state detection threshold. For example, if instability = “4” is the instability detection threshold in the case of FIG. 2, instability = “7” in the upper part of FIG. Qn is generated. In the case of the lower stage, since instability = “1”, unstable state detection data Qn of “0” is generated. The unstable pixel detection unit 12 outputs the unstable state detection data Qn to the unstable state holding data generation unit 13.

  As a result, the unstable pixel detection unit 12 detects that the pixel to be detected is in an unstable state, that is, within a region where target detection is unstable due to sea surface reflection or the like. This is because the receiving unit or the like appropriately adjusts STC (sea surface reflection removal), and in a situation where sea surface reflection is detected without regularity without appearing at the same position for each scan, This is because, in the detected pixel, each bit of the behavior data string, that is, behavior data, has a high probability that “1” and “0” are irregularly arranged, and the degree of instability increases. On the other hand, in a pixel where a stable target or a target with a low detection probability is detected compared to sea surface reflection or a pixel where nothing is detected, each bit of the behavior data string, that is, behavior data, is “1”, “0”. This is because there is a high probability that "" is regularly arranged, and the degree of instability is reduced.

  The unstable state holding data generation unit 13 holds the unstable state detection data Qn and the previous unstable state held corresponding to the pixel address of the unstable state detection data Qn stored in the unstable state holding memory 713. The current unstable state holding data Hn is calculated based on the working data Hn-1. Specifically, when the unstable state detection result is to be held for M scans for the determination target pixel in the unstable state, the unstable state holding data generation unit 13 sets the unstable state detection data Qn to “1”. Then, regardless of the previous value of the unstable state holding data Hn-1, the current unstable state holding data Hn is set to "M" (M is an integer) and output. If the unstable state detection data Qn is “0”, the unstable state holding data generation unit 13 subtracts 1 from the previous value of the unstable state holding data Hn−1 to indicate the current unstable state. Output as holding data Hn. Then, the unstable state holding data generation unit 13 does not perform subtraction if the unstable state detection data Qn is “0” and the previous unstable state holding data Hn−1 is “0”. This unstable state holding data Hn is output as “0”. The unstable state holding data generation unit 13 outputs the current unstable state holding data Hn to the unstable state holding memory 713 and the sea surface reflection area determination unit 14.

  The unstable state holding memory 713 has the same address configuration as that of the behavior data memory 711 described above, and has a capacity capable of storing the integer “M” +1 for each pixel address. In the unstable state holding memory 713, the current unstable state holding data Hn output from the unstable state holding data generation unit 13 is updated and stored in the corresponding pixel address.

  By performing such processing, for pixels in which an unstable state is detected, even if the stable state is continuously detected thereafter, a predetermined number of times including the timing of the present unstable state detection (the above example) In the case of M scans), the unstable state holding data Hn output to the sea surface reflection region determination unit 14 does not become “0”. Accordingly, the unstable state can be held for a predetermined number of scans (M times) for the pixels in which the unstable state is detected. This is a process corresponding to the fact that the boundary of the sea surface reflection region cannot be clearly defined. Specifically, the sea surface reflection changes due to adjustments of sea conditions, wind direction, antenna height, STC, and the like, and becomes weaker as the distance from the ship increases. For this reason, the boundary of the sea surface reflection cannot be clearly demarcated, and even when the unstable state temporarily changes to the stable state, the probability of the sea surface reflection is high. Therefore, by performing such processing, it is possible to prevent the sea surface reflection from being emphasized in the processing described later.

  The sea surface reflection area determining unit 14 determines whether Hn = 0 or Hn ≠ 0 with respect to the input unstable state holding data Hn, and if the unstable state holding data Hn ≠ 0. For example, the pixel corresponding to the unstable state holding data Hn is detected as the sea surface reflection region setting reference pixel. When the sea surface reflection area determination unit 14 detects the sea surface reflection area reference pixel, the sea surface reflection area determination unit 14 enlarges the sea surface reflection area in the distance R direction and the azimuth Θ direction with reference to the sea surface reflection area reference pixel. Determine the sea reflection area.

  For example, FIG. 3 is a diagram showing an enlarged concept of the sea surface reflection area, (A) shows an enlargement concept for one sea surface reflection area reference pixel, and (B) shows an enlarged sea surface reflection area by each sea surface reflection area reference pixel. The superposition concept of is shown.

  In more detail with reference to FIG. 3, when the sea surface reflection region determination unit 14 detects the sea surface reflection region reference pixel 401 as shown in FIG. 3A, the sea surface reflection region in the distance R direction and the azimuth Θ direction. The enlarged sea surface reflection area 410 is determined by selecting a plurality of pixels in the orthogonal coordinate system so as to enlarge. At this time, the sea surface reflection area determining unit 14 determines the predetermined value so that the sea surface reflection area reference pixel 401 is closest to the center of the sweep in the distance direction and is closest to the sweep rotation direction in the enlarged sea surface reflection area 410. A pixel portion (in FIG. 3, three pixels in both the distance direction and the sweep rotation direction) is enlarged as a sea surface reflection region, and an enlarged sea surface reflection region 410 is set.

  Such setting of the enlarged sea surface reflection region is performed every time the unstable state holding data Hn ≠ 0 is received. Then, as shown in FIG. 3B, the sea surface reflection area determination unit 14 stores the expanded sea surface reflection area 410 based on the sea surface reflection area reference pixel 401 and the expanded sea surface reflection based on the sea surface reflection area reference pixel 402. The combined sea surface reflection region 400 is set by combining the region 420, the enlarged sea surface reflection region 430 based on the sea surface reflection region reference pixel 403, and the enlarged sea surface reflection region 440 based on the sea surface reflection region reference pixel 404.

  The sea surface reflection area determination unit 14 generates sea surface reflection area data Bn indicating whether the pixel corresponds to the synthetic sea surface reflection area 400 and outputs the sea surface reflection area data Bn to the W data generation unit 6. Specifically, the sea surface reflection area determination unit 14 generates sea surface reflection area data Bn = 1 if the pixel is within the synthetic sea surface reflection area 400, and the sea surface reflection area data if the pixel is outside the synthetic sea surface reflection area 400. Bn = 0 is generated and output to the W data generator 6.

  By performing such processing, not only the pixels that are actually detected as unstable but also the pixels that are likely to be unstable in the vicinity of the pixels are enlarged with reference to the pixels. The reflection area can be set. This is because the vicinity of pixels in an unstable state is naturally likely to be in an unstable state, and as a result, a two-dimensional enlargement setting of the sea surface reflection suppression region can be performed.

  FIG. 4 is a diagram showing an image example of the sea surface reflection area determined by the sea surface reflection area determination unit 14. In FIG. 4, 500A, 500B, and 500C indicate detected sea surface reflection areas, and the sea surface reflections detected by the small circle group indicated by 501. Further, 502A is a stable ship echo, 502B is a stable buoy echo, 503 is a mobile ship echo, 504 is a target echo with a low detection probability, and 505A is radar interference.

  As shown in FIG. 4, pixels within a predetermined enlarged range are set as the sea surface reflection areas 500A, 500B, and 500C with reference to the sea surface reflection 501 group that is actually detected to be unstable.

  The continuity detection unit 9 includes a buffer memory that stores echo data Xn input from the sweep memory 4 for a predetermined direction, and detects the continuity of the echo data Xn to be determined.

  5A and 5B are diagrams for explaining the concept of continuity. FIG. 5A is an explanatory diagram for determining continuity, and FIG. 5B is a diagram for describing an example of determining continuity for each target, interference, and white noise.

  The continuity detection unit 9 extracts echo data existing in the continuity determination reference area 110 including echo data to be determined for continuity from the buffer memory. Here, the continuity determination reference area 110 includes, for example, echo data 101N and 101F adjacent in the distance R direction and echo data 102C and 103C adjacent in the azimuth Θ direction with respect to the echo data 100 to be determined, In FIG. 5A, this is a region surrounding echo data 102N, 102F, 103N, and 103F adjacent to each other in four directions extending at an interval of about 45 ° between the distance R direction and the azimuth Θ direction.

  The continuity detector 9 detects the data levels of the echo data 100, 101N, 101F, 102N, 102C, 102F, 103N, 103C, and 103F. The continuity detection unit 9 determines that there is continuity if the number of echo data having a level equal to or higher than a preset detection threshold is equal to or greater than a preset determination threshold, and continues to the W data generation unit 6. Sex data An = 1 is output. The continuity detection unit 9 determines that there is no continuity if the number of echo data having a level equal to or higher than a preset detection threshold is similarly less than a preset determination threshold, and continues to the W data generation unit 6. Sex data An = 0 is output.

  For example, as shown in FIG. 5B, since the target 901 is a collection of echo data having a level equal to or higher than the detection threshold, the echo data having a level equal to or higher than the detection threshold existing in the continuity determination reference region 110. There are many. In addition, since the interference 902 includes echo data having a level equal to or higher than a predetermined threshold only in the same azimuth direction, the number of echo data having a level equal to or higher than the detection threshold existing in the continuity determination reference region 110 is reduced. Further, since the white noise 903 is often generated in a single shot, the echo data having a level equal to or higher than the detection threshold existing in the continuity determination reference region 110 is reduced.

  Therefore, the continuity determination threshold is set so that the number of echo data having a level equal to or higher than the detection threshold existing in the continuity determination reference region 110 is larger than the majority of the number of echo data in the continuity determination reference region 110. For example, by setting it to 50%, it is possible to discriminate a target from interference and white noise.

  The W data generator 6 receives the current echo data Xn input from the sweep memory 4, the scan correlation processing result data Yn−1 before one rotation read from the image memory 7, and the continuity from the continuity detector 9. Based on the data An and the sea surface reflection area data Bn from the sea surface reflection area determination unit 14, the current scan correlation processing result data Yn is calculated and output to the image memory 7. The image memory 7 is a memory having a capacity for storing scan correlation processing result data for one antenna revolution, that is, one sweep revolution.

  The W data generation unit 6 is composed of hardware that executes the calculation of the following equation (1).

Yn = α · γ · Xn + βYn−1− (1)
At this time, α and β are set based on whether they are within the sea surface reflection region or outside the sea surface reflection region. Γ is set based on the continuity data An.
In the case of the averaging process (process 1), α + β = 1 and α <β. For example, α = 0.2 and β = 0.8 are set. Here, γ = 1.0. By using such processing 1, the averaging (integration) processing is executed.
That is, in the echo data in which a high level is detected suddenly or discontinuously and at a low frequency in each successive scan, the value of the scan correlation processing result data becomes a low level. On the other hand, in the echo data in which the high level is continuously detected in each successive scan, the level of the scan correlation processing result data gradually increases, and the high level is continuously maintained. Thereby, even when high-level echo data is suddenly detected as in the case where sea surface reflection suddenly appears, the scan correlation processing result data, that is, display luminance or the like can be suppressed to a low level. Further, even if the echo to the target disappears, it does not suddenly become “0”, and the echo can be displayed by an afterglow display or the like. As a result, it is possible to suppress the echoes of sea surface reflection that are frequently changed, and to display a target such as a buoy present in the sea surface reflection region for easy identification.

FIG. 6 is a diagram showing the transition of the scan correlation processing result data by the processing 1. FIG. 6A shows the case of real echoes with a target whose detection frequency is 2/3 in successive scans, and FIG. 6B shows the sea surface where the detection frequency in successive scans is halved. The case of echo by reflection is shown. In FIG. 6, the broken line indicates the level of echo data to be input, and the solid line indicates the level of scan correlation processing data, and each data is normalized data with the maximum value being “1”.
As shown in FIG. 6A, the output level of the real echo of the target with the detection frequency of 2/3 is higher than the output level of the sea surface reflection echo with the detection frequency of 1/2. Specifically, in the vicinity of the 20th scan, the output level is about 0.7 due to the actual echo of the target having a detection frequency of 2/3. On the other hand, as shown in FIG. 6 (B), the output level is about 0.5 with an echo of sea surface reflection with a detection frequency of ½. As described above, when the processing 1 is used, the sea surface reflection and the target can be clearly identified.

In the case of enhancement processing (processing 2), α + β> 1 and α> β. For example, α = 1.0 and β = 0.8 are set. Again, γ = 1.0. Emphasis processing is executed by using such processing 2.
That is, even in echo data in which a high level is detected suddenly or discontinuously and at a low frequency in each successive scan, the level of the scan correlation processing result data is continuously maintained at a high level. As a result, the level of the scan correlation processing data for the corresponding pixel is kept high with respect to the target moving at a high relative speed with respect to the own apparatus. As a result, it is possible to reliably identify targets with low detection frequency and targets that move at high speed.

In this process 2, the sea surface reflection is also emphasized, and the sea surface reflection cannot be distinguished from a target with low detection frequency or a target moving at high speed.
FIG. 7 is a diagram illustrating the transition of the scan correlation processing result data in the process 2. FIG. 7A shows the case of real echoes with a target whose detection frequency is 2/3 in successive scans, and FIG. 7B shows the sea surface where the detection frequency in successive scans is halved. The case of echo by reflection is shown. Also in FIG. 7, the broken line indicates the level of echo data that is input, and the solid line indicates the scan correlation processing data level that is output. Each data is normalized data with a maximum value of “1”.
As shown in FIGS. 7A and 7B, when processing 2 is used, real echoes of targets with different detection frequencies (detection frequency 2/3) and sea surface reflection echoes (detection frequency 1/2) Therefore, the output level hardly changes. Specifically, in the vicinity of the 20th scan, both the actual echo of the target and the echo of the sea surface reflection are about 0.9. That is, the process 2 indicates that it is inappropriate for suppressing sea surface reflection.

FIG. 8 is a diagram showing the transition of the scan correlation processing result data in the above-described processing 1 and processing 2 for a target with a low detection frequency (such as 1/5). In FIG. 8, the broken line indicates the level of the input echo data, the thick solid line indicates the level of the scan correlation processing result data in process 2, and the thin solid line indicates the level of the scan correlation processing result data in process 1 .
As shown in FIG. 8, when processing 1 is used, the level of echo data of a target with low detection frequency is suppressed, but when processing 2 is used, the level of echo data of a target with low detection frequency is suppressed. In addition, even when it is not detected, it is displayed as an afterimage. That is, processing 2 is effective for detecting a target with a low detection frequency.

  From the above results, when only one of process 1 and process 2 is used, there are both good points and bad points according to each process.

  For this reason, when the sea surface reflection area data Bn = 1, that is, when the pixel corresponding to the current echo data Xn is in the sea surface reflection area, the process 1 is performed, and when the sea surface reflection area data Bn = 0, that is, the current echo. When the pixel corresponding to the data Xn is outside the sea surface reflection area, the processing is switched to processing 2. In the sea surface reflection area, the sea surface reflection is suppressed by the processing 1, and it becomes easy to detect a target such as a buoy existing in the sea surface reflection area. On the other hand, outside the sea surface reflection area where there is no sea surface reflection, it is easy to detect a target with low detection frequency or a target that moves at high speed without enhancing the sea surface reflection by the process 2.

  However, in the process 2, white noise and radar interference are also emphasized, so that the target echo cannot be distinguished from white noise and radar interference.

In such a case, the value of the coefficient γ set based on planar continuity is set as a plurality of values and applied to the process 2. The coefficient γ is set to a value of 0 ≦ γ ≦ 1 according to continuity. At this time, the higher the continuity, the higher the coefficient γ is set. Then, as described above, when there is only continuity presence / absence (An = 1 or An = 0), for example, continuity data An = 1 indicating continuity is set to γ = 1.0. When continuity data An = 0, meaning no continuity, γ = 0, 0.2, or the like is set.
In the following, an example is described in which γ = 0.2 is set when continuity data An = 0, and γ is set only outside the sea surface reflection region.

  When continuity data An = 1, that is, when there is continuity, γ = 1.0, so the coefficient related to the current echo data Xn is α. As a result, the scan correlation processing result data is generated outside the sea surface reflection area as described above. Here, when there is planar continuity, there is a high possibility that it is an echo from the target, and even if the level of the echo data is continuously low, the target detected as having continuity is Further, even if it is not detected with a very high frequency in time, the scan correlation processing data is maintained at a high level.

  On the other hand, when continuity data An = 0, that is, when there is no continuity, γ = 0.2, so the coefficient related to the current echo data Xn is 0.2α. With the same detection frequency, the level of the scan correlation processing data is significantly lower than in the case of γ = 1.0 described above. Here, the case where there is no planar continuity is likely to be white noise or interference from another radar device. Therefore, these white noise and interference result in the scan correlation processing data being maintained at a low level. As a result, the use of the coefficient γ based on continuity can suppress the display of white noise and radar interference at a high level. Thereby, a target with low detection frequency or a target moving at high speed can be distinguished from white noise and radar interference.

9 and 10 are diagrams illustrating the transition of the scan correlation processing result data by the processing 2. FIG.
FIG. 9A shows the case of real echo using a target whose detection frequency is 1/5 in successive scans, and FIG. 9B is the radar interference whose detection frequency is 1/5 in successive scans. The case of echo by is shown. FIG. 10A shows the case of real echo with a target whose detection frequency is 1/2 in the continuous scan, and FIG. 10B is that the detection frequency is 1/2 in the continuous scan. The case of echo due to white noise is shown. 9 and 10, the broken line indicates the level of echo data to be input, and the solid line indicates the level of scan correlation processing data, and each data is normalized data with the maximum value being “1”. It is.
The target is determined to have continuity by detecting the continuity described above, and γ = 1.0 is set. Radar interference and white noise are determined to have no continuity, and γ = 0.2 is set. By applying these to equation (1), the results of FIGS. 9 and 10 are obtained.

  As shown in FIGS. 9A and 9B, even if the detection frequency is both 1/5, the output level of the echo of the target having continuity is the echo of the radar interference having no continuity. Higher than the output level. Specifically, in the actual echo of the target having continuity, the output level changes from about 0.4 to 1.0, and in the radar interference echo having no continuity, the output level is about 0. It keeps at 3 or less.

  Further, as shown in FIGS. 10A and 10B, even if the detection frequency is the same as 1/2, the output level of the real echo of the target having continuity is white that does not have continuity. It becomes higher than the output level of the noise echo. Specifically, in the real echo of the target having continuity, the output level changes from about 0.8 to 1.0, and in the white noise echo having no continuity, the output level is about 0.00. It changes between 4 and 0.6. In this way, if the process 2 and γ are used in combination, radar interference and white noise can be clearly identified from the target.

  The current scan correlation processing result data Yn generated by the W data generator 6 is written in the image memory 7 at the pixel address designated by the drawing address generator 5. When the display 8 is raster-scanned by a display control unit (not shown), the image memory 7 reads the scan correlation processing result data Yn in synchronization with the raster operation. The display control unit forms image data having a predetermined luminance and chromaticity based on the read scan correlation processing result data Yn, and controls the display 8 based on the image data.

  By performing such a configuration and scan correlation processing, an image as shown in FIG. 11 can be displayed.

FIG. 11 is a diagram illustrating an example of an image when the scan correlation process of the present embodiment is performed.
FIG. 12 is a diagram illustrating an example of an image when the processing of the present embodiment is not performed, and FIG. 13 is a diagram illustrating an example of an image when the above-described processing 1 is applied to all pixels. 14 is a diagram illustrating an image example when the above-described processing 2 is applied to all pixels. In the following description, a case where the luminance is changed according to the data level is shown. Moreover, the sea surface reflection setting area 500 in each figure is shown conceptually, and more specifically, is configured by sea surface reflection areas 500A, 500B, and 500C shown in FIG.

  When only the process 1 is used, the process 1 is an average process. Therefore, as shown in FIG. 13, the echoes 512A ′ and 512B ′ of the target that are stably detected are displayed with high brightness and echoes of the sea surface reflection. 511 ′ and interference 515A ′ and 515B ′ are suppressed. However, the target echo 514 ′ with low detection frequency and the target echo 513 ′ that moves at high speed are displayed only at low luminance, making it difficult to identify them.

  Further, when only the process 2 is used, the process 2 is an emphasis process. Therefore, as shown in FIG. 14, the echoes 522A ′ and 522B ′ of the target that are stably detected are displayed with high luminance and moved at high speed. The target target echo image 523 ′ is displayed so as to be tailed with high brightness, and the target echo 524 ′ with low detection frequency is displayed with high brightness when detected, and is displayed as an afterimage even when it is not detected. Is done. However, since the sea surface reflection echo 521 ′ and the interference echo 525 ′ are also displayed with high brightness, it is difficult to identify them.

  Further, when the scan correlation process is not performed, since the averaging process and the enhancement process are not performed, the target echoes 502A and 502B that are stably detected and the target echo 503 that moves at high speed are obtained as shown in FIG. Displayed with high brightness. However, when the sea surface reflection echo 501 and the interference echo are also detected, they are displayed with high luminance, and the target echo 504 with a low detection frequency may or may not be displayed. As a result, it becomes difficult to identify them.

  Compared with the case where only the processing 1 and the processing 2 and the scan correlation processing are not performed, by using the configuration and processing of the present application described above, as shown in FIG. 11, (1) in the sea surface reflection area setting area 500 The echo image 501 ′ of the sea surface reflection generated in FIG.

  (2) The echo images 502A ′ and 502B ′ of a target (such as a ship or a buoy) that are stably detected regardless of whether they are inside or outside the sea surface reflection area setting section 500 are displayed as high-intensity echo images.

  (3) An echo image 503 ′ of a target (such as a ship) that moves at a high speed outside the sea surface reflection area setting area 500 is displayed such that the luminance is tailed from the head in the traveling direction.

  (4) The echo image 504 'of the target having a low detection frequency outside the sea surface reflection area is displayed with high luminance when detected, and is displayed with afterglow when not detected.

  (5) With respect to radar interference with low or no planar continuity, the echo image 505A 'of the current interference and the echo image 505B' of the afterimage due to the previous interference are displayed only with extremely low luminance.

  In this way, by performing the configuration and processing of the present embodiment, the echoes of the target to be displayed are displayed reliably and with high brightness regardless of the detection frequency, the moving speed, etc., and there is no need for sea surface reflection, radar interference, etc. The echo can be suppressed.

  As described above, by using the configuration and processing of the present embodiment, the sea surface reflection area is automatically detected from the instability of the echo data, and by changing the calculation coefficient of the scan correlation processing inside and outside the sea surface reflection area, Scan correlation processing suitable for each can be executed. This eliminates the need for the operator to determine and select an appropriate scan correlation process, thereby preventing a danger due to an erroneous selection of the scan correlation process and realizing an easy-to-handle radar device with a scan correlation function. At this time, the range of the sea surface reflection changes due to adjustment of the sea conditions, wind direction, STC, etc., but the sea surface reflection area is automatically detected, so that the optimum scanning is automatically performed following such a change in the sea surface reflection. Correlation processing can be performed.

  In addition, the setting as the sea surface reflection area determined based on the degree of instability is maintained for a predetermined scan, and further, the area expanded in the distance direction and the azimuth direction is set as the sea surface reflection area. It is possible to prevent erroneous identification processing in the vicinity.

  Furthermore, by changing the calculation coefficient of scan correlation processing based on the continuity of echo data, radar interference with low continuity can be suppressed from the beginning and the afterglow level can be lowered. Even if the echoes of the target are infrequent, the echoes of the target with high continuity can be emphasized and displayed. As a result, the actual target and the radar interference can be easily identified on the video. Even if white noise increases due to increased sensitivity due to reception sensitivity adjustment, white noise with low continuity is suppressed, so white noise is cumulatively added as in conventional enhancement processing, resulting in a white screen. There is no defect that is buried with noise, and the sensitivity adjustment operation is easy and easy to see.

  In the above description, an example in which the setting of the sea surface reflection region determined based on the degree of instability is extended in time and then extended in the azimuth direction and the distance direction is shown. The processing order may be changed.

In the above description, the example in which the setting of γ based on the continuity data An is binarized has been shown. However, γ may be set in multiple values based on the continuity data. Thereby, the display based on the effect based on continuity can be performed more significantly.
In the above description, γ is applied only to the scan correlation processing calculation outside the sea surface reflection region, but may be applied to the scan correlation processing calculation within the sea surface reflection region.
In the above description, the example in which the sea surface reflection area is enlarged to the far side of the sea surface reflection area reference pixel and the scan traveling direction side with respect to the scan center is shown. However, the distance from the sea surface reflection area reference pixel is the center. You may make it enlarge and set a predetermined number of pixels to a direction and an azimuth | direction direction.

  In the above description, the sea surface reflection area is enlarged in the distance direction and the azimuth direction based on the unstable state holding data Hn. However, the distance of the sea surface reflection area is based on the unstable state detection data Qn. The enlargement setting in the direction and the azimuth direction may be performed.

It is a block diagram which shows the main structures of the radar apparatus of embodiment of this invention. It is a figure which shows the relationship between the behavior data sequence Pn, instability, and unstable state detection data. It is a figure which shows the expansion concept of a sea surface reflective area | region. It is a figure which shows the example of an image of the sea surface reflection area | region determined by the sea surface reflection area | region determination part. It is a figure explaining the concept of continuity. It is a figure which shows transition of the scan correlation process result data by the process 1. FIG. It is a figure which shows transition of the scan correlation process result data by the process 2. FIG. It is a figure which shows transition of the scan correlation process result data in the process 1 and the process 2 with respect to the target with a low detection frequency. It is a figure which shows transition of the scan correlation process result data of the target and radar interference by the process 2 and (gamma). It is a figure which shows transition of the scan correlation process result data of the target and white noise by the process 2 and (gamma). It is a figure which shows the example of an image at the time of performing the scan correlation process of this embodiment. It is a figure which shows the example of an image when the process of this embodiment is not performed. It is a figure which shows the example of an image at the time of applying the above-mentioned process 1 with respect to all the pixels. It is a figure which shows the example of an image at the time of applying the above-mentioned process 2 with respect to all the pixels.

1-radar antenna, 2-receiver, 3-AD converter, 4-sweep memory, 5-radial drawing address generator, 6-W data generator, 7-image memory, 8-display, 9-continuity Detection unit, 10-sea surface reflection region detection unit, 11-behavior data generation unit, 12-unstable pixel detection unit, 13-unstable state holding data generation unit, 14-sea surface reflection region determination unit, 711-behavior data memory 713-unstable state holding memory, 500-sea reflection area setting area

Claims (4)

Received data acquisition means for sequentially acquiring received data in a polar coordinate system obtained by rotating the sweep;
Image data generation and storage means for converting the received data of the polar coordinate system into image data of an orthogonal coordinate system, and generating and storing each image data so as to be updated for each rotation of the sweep according to the received data;
Display means for sequentially reading out and displaying the image data stored in the image data generation storage means;
A device for detecting and displaying a target equipped with
In addition to detecting whether the received data is equal to or greater than a preset threshold, the degree of instability is detected based on the transition of detection results for the past several scans including the current time corresponding to the received data for which the threshold is detected. The sea surface reflection area is determined based on the degree of instability, and a predetermined range spreads in the distance direction and the azimuth direction including the pixel with respect to the pixel corresponding to the reception data that is the determination criterion of the sea surface reflection area. A sea surface reflection area detecting means for setting a portion having a sea area reflection area as an enlarged sea surface reflection area;
The image data generation and storage means performs an image data generation process by an averaging process or an integration process based on current data and past data in the sea surface reflection area and the enlarged sea surface reflection area, and the sea surface reflection area and the enlargement area Outside the sea surface reflection area, perform image data generation processing to emphasize the current data,
A device that detects and displays a target. An area that includes received data to be judged and is within a predetermined range extending in the distance direction and the azimuth direction is set as a judgment reference area, and continuity is determined based on the number of pieces of received data in the judgment reference area that are equal to or greater than the threshold. Comprising continuity detecting means for detecting
The image data generation storage unit performs image data generation processing by adjusting the specific gravity of the reflection of the current data based on the continuity.
An apparatus for detecting and displaying the target according to claim 1. The continuity detecting means, when detecting that the detected number is equal to or greater than a preset continuity detection threshold, determines that the received data to be determined has continuity,
The apparatus according to claim 2, wherein the image data generation and storage unit adjusts the specific gravity of the reflection according to the presence or absence of the continuity.   The said image data production | generation storage means performs the adjustment of the specific gravity of the said reflection based on the said continuity only when it is outside the said sea surface reflective area | region and the said enlarged sea surface reflective area | region. A device that detects and displays marks.