JP2012108049A - Signal processor, radar device, signal processing method and signal specific program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a signal processor, a radar device, a signal processing method and signal specific program with which unnecessary signals are removed from input signals and echo signals due to reflection on a target are detected.SOLUTION: In a signal processor in which echo signals due to reflection on a target can be detected from received signals, the signal level of input signals is detected at a signal level detection part 21 and the rising edge of the echo signals at the input signal is detected by a rising edge detection part 22. The maximum level of the signal level of signals after the start of the detected rising edge is specified by a threshold determination part 25. Based on the maximum value specified, the echo signal due to reflection at a target is detected by an echo signal detection part 26.

Description

  The present invention relates to a signal processing device, a radar device, a signal processing method, and a signal specifying program for detecting an echo signal caused by reflection at a target in a detection area from a received signal.

  Conventionally, there are various radar devices that transmit a radio signal to a detection area to detect a target in the detection area. The radar apparatus receives the echo signal formed by reflecting the transmitted radio wave signal from the target, thereby forming and displaying a detection image for the detection area. However, depending on the structure of the target, the transmitted radio wave signal is multiple-reflected by the target, and the radar device receives the echo signal due to the multiple reflection, so that the image of the target that does not actually exist in the detection area (Radar false image) may be displayed.

  FIG. 17 is a diagram illustrating a detection image including a radar false image. FIG. 17 is a detection image corresponding to the distance and angle with respect to the ship on which the radar device is mounted, and the detection result of the detection region where the target exists from the distances R1 to R2 is the white color in the figure. Shown in part. As shown in the figure, in the formed detection image, a radar false image appears at distances R2 to R3 where no target actually exists. As described above, when the detection image is not accurately formed, the size, position, representative point, and the like of the target cannot be accurately detected. Therefore, in order to form a more accurate detection image, an apparatus for removing a radar false image has been proposed (see, for example, Patent Document 1).

  When the target is moving, the apparatus described in Patent Document 1 obtains the width of the target from the length of the target obtained from the generated target video and a predetermined coefficient, and the course of the target A pseudo false image is generated by moving the target image generated in the vertical direction by the width of the target. Then, a range in which the target image and the pseudo false image image overlap each other is displayed as a false image due to multiple reflection on the target, with the overlapping portion removed from the generated target image.

  Further, the cause of the radar false image is not limited to multiple reflection. FIG. 18 is a diagram for explaining the cause of the radar false image, and shows a graph in which the signal level of the signal received by the radar apparatus is associated with the distance from the ship on which the radar apparatus is mounted. When the target actually exists at the distances R1 to R2, the echo signal ideally has a convex waveform between the distance R1 and the distance R2. However, for example, when the signal level of the echo signal rises rapidly when the echo signal is amplified, and the amplifier malfunctions, the falling edge of the waveform of the echo signal exceeds the distance R2 and the target does not exist. The tail is pulled to R3. The signal of the falling part with the tail (hereinafter referred to as a false image signal) causes a radar false image appearing at distances R2 to R3 as shown in FIG.

Japanese Unexamined Patent Publication No. 07-110372

  However, the apparatus described in Patent Document 1 cannot obtain the width of a target when there is no predetermined coefficient, and also has a processing time and a memory capacity used for generating a pseudo-false image. I need. For this reason, the apparatus described in Patent Document 1 cannot effectively remove false images due to multiple reflection. Further, in the case of the cause described with reference to FIG. 18, the apparatus described in Patent Document 1 cannot remove the radar false image.

  Therefore, an object of the present invention is to provide a signal processing device, a radar device, a signal processing method, and a signal specifying program for detecting an echo signal caused by reflection on a target by removing unnecessary signals from an input signal.

  The present invention provides a signal processing device that specifies an echo signal caused by reflection at a target from an input signal, and includes a signal level detection unit, a rising detection unit, and an echo signal specification unit. The signal level detection unit detects the signal level of the input signal. The rise detection unit detects the rise of the echo signal in the input signal. The echo signal specifying unit specifies an echo signal due to reflection on the target from a signal from the start of the rising detected by the rising detection unit until a predetermined time elapses.

  In this configuration, the echo signal is specified from a range from when the echo signal starts to rise until a predetermined time elapses. When the echo signal is specified, even if the rising edge of the echo signal can be detected, if the falling edge is in a state where the tail is drawn, it may not be possible to know how far the end of the echo signal is. Therefore, by estimating the echo signal from the range from the start of the echo signal rise to the lapse of a predetermined time, the unnecessary signal included in the input signal is removed, and only the echo signal is specified. Can do. As a result, an appropriate detection image can be formed from the echo signal. In the following, the echo signal refers to a signal due to reflection on a target, and is distinguished from a signal due to multiple reflection.

  The signal processing device according to the present invention further includes a maximum value specifying unit that specifies the maximum value of the signal level of the signal from the start of the rising detected by the rising detection unit until the predetermined time elapses. The echo signal specifying unit specifies the echo signal based on the maximum value specified by the maximum value specifying unit.

  In this configuration, an echo signal due to reflection at the target is specified based on the maximum value of the signal level of the input signal. As described above, when the trailing edge is in a trailing state, it may be impossible to determine how far the end of the echo signal is. Therefore, by estimating the range of the echo signal from the maximum value of the echo signal, it is possible to remove the portion estimated as an unnecessary signal included in the input signal and specify only the echo signal. As a result, an appropriate detection image can be formed from the echo signal.

  The signal processing apparatus according to the present invention further includes a threshold value determination unit that determines a threshold value of the signal level based on the maximum value. The echo signal specifying unit specifies a signal having a signal level equal to or higher than the threshold value determined by the threshold value determining unit as an echo signal.

  In this configuration, an example using a threshold value determined based on the maximum value of the signal level is shown as a specific example for specifying the echo signal.

  In the signal processing device according to the present invention, the echo signal specifying unit specifies, as an echo signal, a signal from when the signal level reaches the threshold value after reaching the maximum value specified by the maximum value specifying unit.

  In this configuration, as a specific example of the specific range of the echo signal using the threshold value, an example in which the position of the signal having the maximum signal level is set as the start position of the specific range is shown.

  In the signal processing device according to the present invention, the maximum value specifying unit includes an end level specifying unit and a determining unit. The end level specifying unit specifies the signal level of the signal at the maximum portion of the rising detected by the rising detection unit. The determination unit determines whether there is a signal level greater than the signal level specified by the end level specifying unit. If the determination unit determines that there is a signal level greater than the signal level specified by the end level specification unit, the maximum value specification unit sets the signal level higher than the signal level specified by the end level specification unit to the maximum value. Is identified. The echo signal specifying unit specifies a signal from the local maximum until the signal level reaches a threshold value as an echo signal.

  In this configuration, a specific method for specifying the maximum value of the signal level and a specific example of the specific range of the echo signal are shown.

  The signal processing apparatus according to the present invention further includes a calculation unit. The calculation unit calculates a time from the start of the rising detected by the rising detection unit until the signal level reaches the maximum value specified by the maximum value specifying unit. The echo signal specifying unit specifies, as an echo signal, a signal from the start of rising until the time at least double the time calculated by the calculating unit has elapsed.

  In this configuration, as a specific example for specifying the echo signal, an example in which the specific range of the echo signal is determined by estimating the fall time of the echo signal from the calculated rise time of the signal is shown.

  The signal processing apparatus according to the present invention further includes a correction unit. The correction unit corrects the signal level of the input signal after the signal specified by the echo signal specifying unit.

  In this configuration, an example of correcting signals other than the specified echo signal is shown as a specific example of removing unnecessary signals included in the input signal.

  In the signal processing device according to the present invention, the correction unit sets the signal level to a noise level.

  In this configuration, as a specific example of removing unnecessary signals included in the input signal, an example in which the signal level of signals other than the specified echo signal is corrected to a noise level is shown.

  The signal processing apparatus according to the present invention further includes a smoothing unit. The smoothing unit smoothes the signal level detected by the signal level detection unit.

  This configuration shows a specific method for performing signal processing.

  According to the present invention, by estimating the range of the echo signal from the maximum value of the echo signal, it is possible to remove only a portion estimated as an unnecessary signal included in the input signal and specify only the echo signal. As a result, an appropriate detection image can be formed from the echo signal.

1 is a block diagram illustrating a configuration of a radar device according to a first embodiment. It is a block diagram of the function which a signal processing part has. It is a schematic diagram which shows the waveform of the received signal input into the signal processing part. It is a schematic diagram which shows the waveform of the received signal after changing the signal level of a false image signal. It is a figure which shows the detection image formed based on the received signal shown in FIG. It is a flowchart which shows the procedure of the process performed by a signal processing part. It is a block diagram of the function which the signal processing part concerning Embodiment 2 has. It is a schematic diagram which shows the waveform of the received signal input into the signal processing part. It is a flowchart which shows the procedure of the process performed by a signal processing part. It is a block diagram of the function which the signal processing part concerning Embodiment 3 has. It is a schematic diagram which shows the waveform of the received signal input into the signal processing part. It is a flowchart which shows the procedure of the process performed by a signal processing part. It is a block diagram of the function which the signal processing part concerning Embodiment 4 has. It is a schematic diagram which shows the waveform of the received signal before and behind smoothing. It is a schematic diagram which shows the inclination of the calculated signal waveform with the arrow. It is a flowchart which shows the procedure of the process performed by a signal processing part. It is a figure which shows the detection image containing a radar false image. It is a figure for demonstrating the cause of a radar false image.

  Preferred embodiments of a signal processing device, a radar device, a signal processing method, and a signal specifying program according to the present invention will be described below with reference to the drawings. In the embodiments described below, a radar apparatus that includes a signal processing device according to the present invention and is mounted on a ship will be described. Radar equipment emits short-wavelength radio waves to the surrounding direction of the ship on which it is mounted (hereinafter referred to as its own ship) while sequentially changing its direction, and receives the reflected waves, thereby enabling other ships on the sea. Alternatively, target detection is performed to measure the distance and direction to a target such as a bird.

(Embodiment 1)
FIG. 1 is a block diagram illustrating a configuration of a radar apparatus according to the first embodiment. The radar apparatus 1 includes a transmission unit 10, a circulator 11, an antenna 12, a reception processing unit 13, a storage unit 14, and the like. The storage unit 14 is, for example, a ROM (Read Only Memory) or the like, and stores a program 14a necessary for the radar apparatus 1 and various data.

  The transmitting unit 10 is controlled to output a pulse signal at a predetermined timing, and outputs the pulse signal to the circulator 11 at a set timing using the reference frequency signal. The time length (transmission pulse width) of the pulse signal output from the transmission unit 10 may be determined as one of a short pulse signal, a middle pulse signal, and a long pulse signal according to the detection region. A set of pulse trains may be used. For example, when the pulse width of the pulse signal is increased, the radio wave is less attenuated and can be detected far away. However, since the resolution is lowered, the resolution of the image related to the target is deteriorated. When the pulse width of the pulse signal is shortened, the radio wave is greatly attenuated and cannot be detected far away, but the resolution of the image related to the target is increased.

  The circulator 11 transmits the pulse signal output from the transmission unit 10 to the antenna 12. The antenna 12 is installed in the ship and radiates a pulse signal input via the circulator 11 to the outside with a predetermined directivity while rotating on a horizontal plane at a predetermined rotation speed. In addition, the antenna 12 receives a signal including an echo signal, a noise signal, and the like that are obtained by reflecting a pulse signal emitted from the antenna 12 to a target in the detection area, and outputs the signal to the circulator 11 as a reception signal. The circulator 11 transmits the reception signal output from the antenna 12 to the reception processing unit 13.

  The reception processing unit 13 is a microcomputer, for example, and detects a received signal input via the circulator 11 to detect a target in the detection area. The reception processing unit 13 has functions such as an amplification unit 130, an A / D conversion unit 131, a reception data storage unit 132, and a signal processing unit 133 by executing a program 14 a stored in the storage unit 14.

  The amplification unit 130 amplifies the reception signal input from the antenna 12 via the circulator 11. The amplification unit 130 outputs the amplified received signal to the A / D conversion unit 131. The A / D conversion unit 131 performs analog-digital conversion on the reception signal amplified by the amplification unit 130 at a predetermined sampling time, forms reception data having a predetermined number of bits, and outputs the reception data to the reception data storage unit 132.

  The reception data storage unit 132 includes a so-called sweep memory. The reception data storage unit 132 stores the reception data for one sweep digitally converted by the A / D conversion unit 131 in real time, and the reception data for one sweep is received until the reception data obtained in the following is written again. Store the data. More specifically, the reception data storage unit 132 sequentially receives one sweep in order to sequentially input received data from the short distance side to the long distance side, that is, to line up in the distance direction with reference to the own ship. Remember. At this time, the reception data storage unit 132 includes a plurality of sweep memories so that reception data of a plurality of sweeps arranged in the azimuth direction can be stored.

  The signal processing unit 133 reads reception data from the reception data storage unit 132 as needed, and forms a waveform of a reception signal (input signal). Then, the signal processing unit 133 detects the target in the detection area by detecting only the echo signal from which the false image signal is removed from the received signal. As the detection result, for example, image data is generated and output to a display (not shown). The indicator may be provided in the radar device 1 or may be provided separately from the radar device 1.

  Next, the signal processing unit 133 will be described in detail. In the following description, it is assumed that a target exists from a distance R1 to a distance R2 (> R1) from the ship in the detection area. In other words, the distance R1 is the forefront edge of a target such as a ship, and the distance R2 is the last edge of the target.

  FIG. 2 is a block diagram of functions that the signal processing unit 133 has. FIG. 3 is a schematic diagram illustrating a waveform of a reception signal input to the signal processing unit 133. FIG. 3 is a graph with the horizontal axis representing the distance from the ship and the vertical axis representing the signal level of the received signal input to the signal processing unit 133.

  The signal processing unit 133 has functions such as a signal level detection unit 21, a rising detection unit 22, an image range detection unit 23, a maximum value specification unit 24, a threshold determination unit 25, and an echo signal detection unit 26.

  The signal level detection unit 21 reads the reception data for one sweep from the reception data storage unit 132 as needed to detect the signal level. The signal level detected by the signal level detection unit 21 is associated with each detection distance. In FIG. 3, for example, the signal level of the echo signal formed by reflecting the pulse signal transmitted from the antenna 12 to the frontmost edge of the target is associated with the distance R1.

  The detection distance is calculated by the time from when the pulse signal is transmitted from the antenna 12 until the echo signal corresponding to the pulse signal is received. In FIG. 3, since the target does not exist, the signal level detected by the signal level detection unit 21 until the distance R1 at which the echo signal is not received is a noise level.

  The rise detection unit 22 detects the rise of the echo signal. The rise detection unit 22 detects the rise of the signal when, for example, the difference between the signal levels continuously detected by the signal level detection unit 21 is a predetermined value or more. In the present embodiment, the point corresponding to the rising end portion (maximum portion) of the signal detected by the rising detection unit 22 is the distance R1, that is, the forefront edge portion of the target. In addition, the rising detection method in the rising detection part 22 is not specifically limited, It can change suitably.

  The image range detection unit 23 detects a range in which a detection image is generated based on detection results from the signal level detection unit 21 and the rising detection unit 22. Specifically, the image range detection unit 23 detects a range from the rising of the signal until the signal level of the rising signal is reduced to the noise level as a range for generating the detection image. In the present embodiment, it is assumed that the signal level of the signal becomes a noise level at the distance R3. Therefore, the image range detection unit 23 detects the distances R1 to R3 as a range in which the detection image is generated. Note that the detection image generated from the range detected by the image range detection unit 23 includes a radar false image as shown in FIG.

  The maximum value specifying unit (edge level specifying unit, determination unit) 24 receives the received signal within a predetermined time, for example, within a range corresponding to the pulse width of the transmitted pulse signal, when the rising detection unit 22 detects the rising. The maximum value of the signal level is specified. Specifically, the maximum value specifying unit 24 temporarily sets the signal level at the rising end portion of the signal detected by the rising detection unit 22 to a maximum value temporarily. Thereafter, if the maximum value specifying unit 24 detects a signal level that is higher than the signal level temporarily set to the maximum value in the range detected by the image range detection unit 23, the maximum value specifying unit 24 updates the detected signal level as the maximum value.

  For example, in the case of FIG. 3, the signal level at the distance R1 'is higher than the signal level at the distance R1. Therefore, the maximum value specifying unit 24 specifies the signal level at the distance R1 'as the maximum value. As described above, in the case of an ideal waveform, the signal level at the end portion (distance R1) of the rising edge of the signal becomes the maximum value, but the maximum value subsequently fluctuates depending on the influence of noise. Can specify the maximum value of the signal level in consideration of the influence of noise.

  The maximum value specifying unit 24 specifies the signal level at the terminal end of the signal rise as the maximum value when there is no signal level higher than the signal level at the terminal end of the signal rising.

  The threshold determination unit 25 determines a signal level threshold based on the maximum value specified by the maximum value specification unit 24. The threshold value determination unit 25 determines, for example, 80% of the specified maximum value as the signal level threshold value. The threshold value determination unit 25 uses 80% of the maximum value as the signal level threshold value, but the threshold value determination method can be changed as appropriate according to the user's empirical rules or the performance of the radar apparatus 1.

  The echo signal detection unit (echo signal specifying unit) 26 removes the false image signal from the received signal based on the rising edge of the signal detected by the rising edge detection unit 22 and the threshold value determined by the threshold value determination unit 25, thereby Is detected. The echo signal detection unit 26 sets the point corresponding to the rising end of the signal detected by the rising detection unit 22 as the distance R1, that is, the forefront edge of the target. The echo signal detection unit 26 sets a point corresponding to the threshold signal level determined by the threshold determination unit 25 as the distance R2, that is, the last edge of the target. The echo signal detection unit 26 uses the signals from the distances R1 to R2 as echo signals obtained by reflecting the pulse signal transmitted from the antenna 12 to the target, and the signals from the distances R2 to R3 as false image signals. The echo signal detection unit 26 changes (corrects) the signal level of the signal set as the false image signal to the noise level.

  FIG. 4 is a schematic diagram showing the waveform of the received signal after changing the signal level of the false image signal. FIG. 5 is a diagram showing a detection image formed based on the reception signal shown in FIG. As shown in FIG. 4, by changing the signal level of the false image signal to the noise level by the echo signal detection unit 26, it is possible to detect only the echo signal obtained by removing the false image signal from the received signal. As a result, as shown in FIG. 5, the radar false image appearing in FIG. 17 is eliminated, and a detection image of only the target existing at the distances R1 to R2 can be generated, so that highly accurate target detection can be performed. It becomes possible.

  In this embodiment, the point corresponding to the rising end of the signal detected by the rising detection unit 22 is set as the distance R1, but the point corresponding to the rising start end may be set as the distance R1. In addition, the echo signal detection unit 26 changes the signal level of the signal set as the false image signal to the noise level, but the signal level may be “0”.

  Next, the processing operation of the signal processing unit 133 that detects the echo signal by removing the false image signal will be described in detail. FIG. 6 is a flowchart showing a procedure of processing executed by the signal processing unit 133.

  The signal processing unit 133 determines whether or not received data is stored in the received data storage unit 132 (S1). When the received data is not stored (S1: NO), the signal processing unit 133 ends this process. When the reception data is stored (S1: YES), the signal processing unit 133 acquires the reception data from the reception data storage unit 132 as needed and detects the signal level of the reception signal (S2). Then, the signal processing unit 133 detects the rising edge of the echo signal in the received signal (S3).

  Next, the signal processing unit 133 detects a range from the rising of the signal until the signal level of the rising signal becomes a noise level as a range for generating a detection image (S4). For example, in the case of FIG. 8, signals from distances R1 to R3 are detected as a range for generating a detection image. Subsequently, the signal processing unit 133 specifies the signal level at the rising end portion of the signal having the first peak value as the maximum value (S5).

  Thereafter, the signal processing unit 133 determines whether or not a signal level larger than the signal level specified as the maximum value in S5 is within the range detected in S4 (S6). If there is a signal level (S6: YES), the signal processing unit 133 updates the signal level detected in S6 as the maximum value (S7), and proceeds to the process of S8. When there is no signal level (S6: NO), the signal processing unit 133 proceeds to the process of S8 while keeping the signal level specified in S5 as the maximum value.

  The signal processing unit 133 determines a threshold for the signal level based on the identified maximum value of the signal level (S8). For example, the signal processing unit 133 sets 80% of the specified maximum value as the signal level threshold. Then, the signal processing unit 133 detects an echo signal based on the processing results so far (S9). Specifically, the signal processing unit 133 sets the point corresponding to the rising end portion of the signal detected in S3 as the distance R1, and the point corresponding to the threshold signal level determined in S8 as the distance R2. And the signal processing part 133 makes the signal between distance R1 and R2 the echo signal which the pulse signal transmitted from the antenna 12 reflected on the target. In addition, the signal processing unit 133 sets the signal after the distance R2 in the range detected in S4 as a false image signal, and changes the signal level of the false image signal to a noise level. Thereafter, the signal processing unit 133 ends this processing.

  Note that, for example, image data of a detection image converted from an R-θ coordinate system shown in FIG. 5 to an XY coordinate system signal is generated based on the processing result performed by the signal processing unit 133, and Each process in the radar apparatus 1 is executed, such as detecting a region surrounding the target and calculating a representative point thereof.

  As described above, the radar apparatus 1 according to the present embodiment determines a threshold value from the maximum value of the signal level of the received signal, and detects an echo signal obtained by removing the false image signal from the received signal based on the threshold value. Yes. As a result, the radar apparatus 1 can remove the radar false image from the detected image without requiring complicated arithmetic processing and storing data necessary for the processing in advance. Can be detected.

  In this embodiment, the rising end portion of the signal is used as the start end portion of the echo signal. However, the echo signal detecting portion 26 detects a signal having a signal level equal to or higher than the threshold value as the start end portion of the echo signal. Alternatively, the detection range can be changed as appropriate. In addition, the method of detecting the rise by the rise detection unit 22 and the method of determining the maximum value by the maximum value specifying unit 24 are not limited to the contents described in the present embodiment.

(Embodiment 2)
Next, Embodiment 2 of the signal processing apparatus according to the present invention will be described. In the present embodiment, the configuration of the radar apparatus 1 shown in FIG. 1 is the same, but the function and operation of the signal processing unit 133 are different from those in the first embodiment. Hereinafter, differences from the first embodiment will be described.

  FIG. 7 is a block diagram of functions of the signal processing unit 133 according to the second embodiment. FIG. 8 is a schematic diagram illustrating a waveform of a reception signal input to the signal processing unit 133.

  The signal processing unit 133 according to the present embodiment includes functions such as a signal level detection unit 21, a rising detection unit 22, an image range detection unit 23, a maximum value specifying unit 24, a distance calculation unit 27, and an echo signal detection unit 26. Since the signal level detection unit 21, the rising detection unit 22, the image range detection unit 23, and the maximum value specifying unit 24 are the same as those in the first embodiment, description thereof is omitted.

  The distance calculating unit 27 calculates a distance corresponding to the time from when the rising edge of the signal detected by the rising edge detecting unit 22 is detected to when the maximum value signal level specified by the maximum value specifying unit 24 is detected. In the present embodiment, as shown in FIG. 8, the point corresponding to the rising start end of the signal detected by the rising detection unit 22 is set as the distance R1, that is, the forefront edge of the target. Further, a point corresponding to the maximum signal level specified by the maximum value specifying unit 24 is set as a distance R1 '. The distance calculation unit 27 calculates a distance (R1′−R1) from the distance R1 to R1 ′. This calculated distance (R1'-R1) is the distance related to the rise of the echo signal.

  The echo signal detection unit 26 detects an echo signal based on the calculation result by the distance calculation unit 27. The echo signal detection unit 26 sets a position that is a distance (R1'-R1) behind the distance R1 'corresponding to the maximum signal level as a distance R2 that is the last edge of the target. In other words, the echo signal detection unit 26 assumes that the fall time of the echo signal is the same as the rise time of the echo signal, and sets the distance R2 when the double of the rise time of the echo signal has elapsed from the distance R1. . Then, the echo signal detection unit 26 uses a signal between the distances R1 and R2 as an echo signal and a signal after the distance R2 as a false image signal.

  The echo signal detection unit 26 changes the signal level of the signal set as a false image signal to a noise level. In the present embodiment, the echo signal detection unit 26 changes the signal level to gradually become a noise level from the distance R1 'to R2, as indicated by a one-dot chain line in FIG. As a result, as in the first embodiment, only the echo signal obtained by removing the false image signal from the received signal can be detected. Note that the echo signal detection unit 26 may change the signal level of the signal after the distance R2 to a noise level, as shown in FIG.

  Next, the processing operation of the signal processing unit 133 will be described in detail. FIG. 9 is a flowchart showing a procedure of processing executed by the signal processing unit 133.

  The signal processing unit 133 determines whether or not reception data is stored in the reception data storage unit 132 (S11). When the reception data is not stored (S11: NO), the signal processing unit 133 ends this process. When the received data is stored (S11: YES), the signal processing unit 133 acquires the received data from the received data storage unit 132 as needed and detects the signal level of the received signal (S12). Then, the signal processing unit 133 detects the rising edge of the signal (S13). The signal processing unit 133 detects a range for generating a detection image from the received signal (S14).

  Next, the signal processing unit 133 calculates a distance (R1′−R1) from the distance R1 to R1 ′ in FIG. 8 (S15). Then, the signal processing unit 133 sets a position that is behind the distance (R1′−R1) from the distance R1 ′ as a distance R2 that is the last edge of the target, and outputs a signal between the distances R1 and R2 as an echo signal. (S16). Thereafter, the signal processing unit 133 ends this processing.

  As described above, the radar apparatus 1 according to the present embodiment does not require complicated arithmetic processing as in the first embodiment, and can detect a detection image even if data necessary for the processing is not stored in advance. As a result, it is possible to detect a target with high accuracy.

(Embodiment 3)
Next, a third embodiment of the signal processing apparatus according to the present invention will be described. In the present embodiment, the configuration of the radar apparatus 1 shown in FIG. 1 is the same, but the function and operation of the signal processing unit 133 are different from those in the first embodiment. Hereinafter, differences from the first embodiment will be described.

  FIG. 10 is a block diagram of functions of the signal processing unit 133 according to the third embodiment. FIG. 11 is a schematic diagram illustrating a waveform of a reception signal input to the signal processing unit 133.

  The signal processing unit 133 includes functions such as a signal level detection unit 21, a rising detection unit 22, an image range detection unit 23, a transmission pulse information acquisition unit 28, and an echo signal detection unit 26. Since the signal level detection unit 21, the rise detection unit 22, and the image range detection unit 23 are the same as those in the first embodiment, description thereof is omitted.

  The transmission pulse information acquisition unit 28 acquires information related to the pulse signal transmitted from the transmission unit 10. Specifically, the transmission pulse information acquisition unit 28 acquires the pulse width (time width) of the transmitted pulse signal.

The echo signal detection unit 26 detects an echo signal from the reception signal based on the pulse width of the pulse signal acquired by the transmission pulse information acquisition unit 28. When the pulse signal transmitted from the antenna 12 is reflected by the target, the antenna 12 receives an echo signal having the same pulse width. Therefore, as shown in FIG. 11, the echo signal detection unit 26 is the last edge of the target from the start end of the rise detected by the rise detection unit 22 to the rear of the pulse width of the transmitted pulse signal. The distance is R2. Then, the echo signal detection unit 26 uses a signal after the distance R2 as a false image signal. Note that the echo signal detection unit 26 may convert the signal level of the signal that is a false image signal into a noise level as in the first and second embodiments. Next, the processing operation of the signal processing unit 133 will be described in detail. Describe. FIG. 12 is a flowchart illustrating a procedure of processing executed by the signal processing unit 133.

  The signal processing unit 133 determines whether or not received data is stored in the received data storage unit 132 (S21). When the reception data is not stored (S21: NO), the signal processing unit 133 ends this process. When the reception data is stored (S21: YES), the signal processing unit 133 acquires the reception data from the reception data storage unit 132 as needed and detects the signal level of the reception signal (S22). Then, the signal processing unit 133 detects the rising edge of the signal (S23). The signal processing unit 133 detects a range for generating a detection image from the received signal (S24).

  Next, the signal processing unit 133 acquires information related to the pulse signal from the transmission unit 10 (S25). Specifically, the signal processing unit 133 acquires the pulse width of the transmitted pulse signal. Then, the signal processing unit 133 sets the distance R2 that is the last edge of the target from the start end of the detected signal rise to the rear of the acquired pulse width, and echoes the signal between the distances R1 and R2. It detects as a signal (S26), and complete | finishes this process.

  As described above, the radar apparatus 1 according to the present embodiment does not require complicated arithmetic processing as in the first and second embodiments, and even if data necessary for processing is not stored in advance, The radar false image can be removed from the detected image, and as a result, the target can be detected with high accuracy.

(Embodiment 4)
Next, a fourth embodiment of the signal processing apparatus according to the present invention will be described. In the present embodiment, the configuration of the radar apparatus 1 shown in FIG. 1 is the same, but the function of the signal processing unit 133 is different from that of the first embodiment. Hereinafter, differences from the first embodiment will be described.

  FIG. 13 is a block diagram of functions of the signal processing unit 133 according to the fourth embodiment.

  The signal processing unit 133 according to the present embodiment includes functions such as a signal level detection unit 21, a rising detection unit 22, an image range detection unit 23, a smoothing unit 29, an inclination calculation unit 30, and an echo signal detection unit 26. Since the signal level detection unit 21, the rise detection unit 22, and the image range detection unit 23 are the same as those in the first embodiment, description thereof is omitted.

  The smoothing unit 29 smoothes the signal in the range detected by the image range detection unit 23 using a low-pass filter. FIG. 14 is a schematic diagram showing waveforms of received signals before and after smoothing. The upper part of FIG. 14 shows the waveform of the signal before smoothing, and the lower part shows the waveform of the signal after smoothing. As shown in the figure, the range detected by the image range detection unit 23 and the signals from the distances R1 to R3 are smoothed to facilitate the calculation of the slope of the signal waveform by the slope calculation unit 30 described later. The smoothing process may also be performed in the first to third embodiments.

  The slope calculation unit 30 calculates the slope (differential value) of the signal waveform at each point from the distances R1 to R3 from the smoothing result by the smoothing unit 29. FIG. 15 is a schematic diagram illustrating the slope of the calculated signal waveform with arrows.

  The echo signal detection unit 26 detects an echo signal based on the inclination calculated by the inclination calculation unit 30. The echo signal detection unit 26 refers to the slope of the signal waveform calculated in order from the rising start end, and more specifically, the position where the slope is negative to positive, more specifically, the head of the portion where the slope is continuously negative. Is detected. The echo signal detection unit 26 sets the detected position as the distance R2 of the last edge of the target, and sets the signal after the distance R2 as a false image signal (see FIG. 15). Note that the echo signal detection unit 26 may convert the signal level of a signal that is a false image signal into a noise level, as in the first and second embodiments.

  Next, the processing operation of the signal processing unit 133 will be described in detail. FIG. 16 is a flowchart showing a procedure of processing executed by the signal processing unit 133.

  The signal processing unit 133 determines whether or not received data is stored in the received data storage unit 132 (S31). When the received data is not stored (S31: NO), the signal processing unit 133 ends this process. When the reception data is stored (S31: YES), the signal processing unit 133 acquires the reception data from the reception data storage unit 132 as needed and detects the signal level of the reception signal (S32). Then, the signal processing unit 133 detects the rising edge of the signal (S33). The signal processing unit 133 detects a range for generating a detection image from the received signal (S34).

  Next, the signal processing unit 133 smoothes the signal in the range where the detection image detected in S34 is generated (S35), and calculates the slope of the smoothed signal waveform (S36). Then, the signal processing unit 133 sets the position where the calculated inclination is positive to negative as the distance R2 that is the last edge of the target, and detects a signal between the distances R1 and R2 as an echo signal (S37). Thereafter, the signal processing unit 133 ends this processing.

  As described above, the radar apparatus 1 according to the present embodiment does not require complicated arithmetic processing as in the first and second embodiments, and even if data necessary for processing is not stored in advance, The radar false image can be removed from the detected image, and as a result, the target can be detected with high accuracy. The preferred embodiments of the present invention have been specifically described above, but each configuration, operation, and the like can be appropriately changed and are not limited to the above-described embodiments. For example, in the above-described embodiment, the radar apparatus 1 including the signal processing apparatus according to the present invention has been described. However, a scanning sonar, or a fish detection apparatus that transmits and receives an ultrasonic pulse and its echo signal directly below the own ship. It may be.

1-radar apparatus, 10-transmission unit, 12-antenna, 13-reception processing unit, 21-signal level detection unit, 22-rising detection unit, 23-image range detection unit, 24-maximum value specifying unit, 25-threshold value Determination unit, 26-echo signal detection unit (specification unit, correction unit), 130-amplification unit, 131-A / D conversion unit, 132-received data storage unit, 133-signal processing unit

Claims (15)

In a signal processing device for identifying an echo signal due to reflection on a target from an input signal,
A signal level detector for detecting the signal level of the input signal;
A rise detection unit for detecting the rise of the echo signal in the input signal;
A signal processing apparatus comprising: an echo signal specifying unit that specifies an echo signal caused by reflection from a target from a signal detected by the rising detection unit until a predetermined time elapses from the start of rising. The signal processing device according to claim 1,
A maximum value specifying unit that specifies the maximum value of the signal level of the signal from the start of the rising detected by the rising detection unit until the predetermined time elapses;
The echo signal specifying unit is
The signal processing device, wherein the echo signal is specified based on the maximum value specified by the maximum value specifying unit. The signal processing apparatus according to claim 2,
A threshold value determining unit for determining a threshold value of the signal level based on the maximum value;
The echo signal specifying unit is
A signal processing apparatus characterized in that a signal having a signal level equal to or higher than a threshold determined by the threshold determination unit is identified as an echo signal. The signal processing device according to claim 3,
The echo signal specifying unit is
A signal processing apparatus characterized in that a signal from when the signal level becomes the maximum value specified by the maximum value specifying unit to the threshold value is specified as an echo signal. The signal processing device according to claim 3 or 4,
The maximum value specifying unit includes:
An end level specifying unit for specifying the signal level of the signal at the maximum part of the rising detected by the rising detection unit;
A determination unit for determining the presence or absence of a signal level greater than the signal level specified by the end level specifying unit,
When the determination unit determines that there is a signal level greater than the signal level specified by the end level specifying unit, the signal level higher than the signal level specified by the end level specifying unit is specified as a maximum value,
The echo signal specifying unit is
A signal processing apparatus that identifies a signal from the local maximum until the signal level reaches the threshold value as an echo signal. The signal processing device according to claim 2,
A calculation unit for calculating a time from the start of the rising detected by the rising detection unit until the signal level reaches the maximum value specified by the maximum value specifying unit;
The echo signal specifying unit is
A signal processing device that identifies an echo signal as a signal from the start of rising until a time at least double the time calculated by the calculation unit elapses. The signal processing device according to claim 2, wherein
A signal processing apparatus, further comprising: a correction unit that corrects a signal level of an input signal after the signal specified by the echo signal specifying unit. The signal processing device according to claim 7,
The correction unit is
A signal processing apparatus characterized in that the signal level is a noise level. The signal processing apparatus according to any one of claims 2 to 8,
A signal processing apparatus, further comprising: a smoothing unit that smoothes the signal level detected by the signal level detection unit. The signal processing device according to claim 1,
When detecting an echo signal, which is a reflection of the transmitted pulse signal from the target, from the input signal,
A means for obtaining a time width of the transmitted pulse signal;
The echo signal specifying unit is
The signal processing apparatus, wherein the time width from the start of the rise detected by the rise detection unit is specified as an echo signal due to reflection from a target. A signal processing device according to any one of claims 1 to 10,
A radar device comprising an antenna for transmitting and receiving signals,
The echo signal specifying unit of the signal processing device is
From the signal received by the antenna, identify the echo signal due to reflection at the target,
A radar apparatus, wherein a target in a region where the antenna transmits a signal is detected based on an echo signal detected by the echo signal specifying unit. In a signal processing method for identifying an echo signal due to reflection on a target from an input signal,
Detecting the signal level of the input signal;
Detecting the rise of the echo signal in the input signal;
And a step of identifying an echo signal due to reflection from a target from a signal from the start of the detected rise until a predetermined time elapses. In a signal processing method for identifying an echo signal due to reflection on a target from an input signal,
Detecting the signal level of the input signal;
Detecting the rise of the echo signal in the input signal;
Identifying the maximum value of the signal level of the signal after the start of the detected rise,
Identifying an echo signal due to reflection at the target based on the identified maximum value;
A signal processing method comprising: In a signal identification program executed by a computer for identifying an echo signal due to reflection on a target from an input signal,
Computer
A signal level detector for detecting the signal level of the input signal,
A rise detection unit for detecting the rise of the echo signal in the input signal; and
A signal specifying program that functions as an echo signal specifying unit that specifies an echo signal caused by reflection on a target from a signal from the start of rising detected by the rising detection unit until a predetermined time elapses. In a signal identification program executed by a computer for identifying an echo signal due to reflection on a target from an input signal,
Computer
A signal level detector for detecting the signal level of the input signal,
A rise detection unit for detecting the rise of the echo signal in the input signal;
A maximum value specifying unit that specifies the maximum value of the signal level of the signal after the start of the rising detected by the rising detection unit; and
A signal specifying program that functions as an echo signal specifying unit that specifies an echo signal caused by reflection at a target based on the maximum value specified by the maximum value specifying unit.

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