JP2014178131A - Radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radar device that enables improvement in distance resolving power of a target, and enables a display of a radar picture unlikely to mistake a distance to the target.SOLUTION: A radar device 10 separating a radar picture of a target in a distance direction and displaying the radar picture therein comprises: a reception part (a transmission/reception part 14) that receives a radar echo reflected by the target; and a signal process part 18 that calculates a maximum value of the radar echo in a predetermined range set to the distance direction, performs a process of correcting a value of the radar echo on a side separated away from the radar device 10 in the predetermined range on the basis of a difference between the maximum value and the value of the radar echo on the side separated away therefrom. The radar picture based on the corrected radar echo is displayed.

Description

  The present invention relates to a radar apparatus that displays a radar image of a target separately in a distance direction.

  The radar device transmits a radar signal (detection signal), receives a radar echo reflected by a target such as a ship or an aircraft, displays a radar image, and monitors the direction of the target and the distance to the target. It is a device to do. The direction of the target can be calculated based on the rotation angle of the transmitting antenna that transmits the radar signal. Also, the distance to the target can be calculated based on, for example, the time from when the radar signal is transmitted until the radar echo is received.

  By the way, if radar echoes reflected by a plurality of targets close to each other in the distance direction overlap, it is difficult to separate and identify the targets. Such a decrease in resolution in the distance direction can be avoided by narrowing the pulse width of the radar signal to be transmitted. However, if the pulse width is narrowed, the distance resolution can be increased, but the reception sensitivity is lowered, so that it is particularly difficult to detect a long-distance target (see Patent Document 1).

  As a radar apparatus capable of increasing the distance resolution, there is an apparatus disclosed in Patent Document 2. In this radar apparatus, the frequency is switched for each radar signal and transmitted, and the received radar echo is subjected to inverse Fourier transform corresponding to the transmitted radar signal to generate a radar image having a high distance resolution. Can do.

  However, the radar apparatus requires a complicated processing circuit such as a frequency synthesizer for switching the frequency of the radar signal and an inverse Fourier transform circuit.

  On the other hand, Patent Document 3 discloses a radar apparatus that can improve distance resolution and azimuth resolution by shaping the waveform of a received radar echo.

JP-A-9-203778 JP-A-5-126943 JP 2008-309606 A

  However, with the radar device of Patent Document 3, the resolution in the distance direction and the azimuth direction can be increased, but the detection accuracy of the distance to the target may be reduced. That is, in Patent Document 3, the radar echoes of the targets that are close to each other are separated by shaping the waveform so that the width of the waveform of the radar echo is narrow. In this case, since the waveform of the bidirectional radar echo between the side close to the radar device and the side away from the radar device is shaped, the position of the target displayed based on the shaped radar echo changes. There is a problem. In other words, when the waveform of the radar echo on the side close to the radar device is shaped, the position of the target moves and is displayed in a direction away from the radar device, so the distance from the radar device to the target is There is a risk of misunderstanding.

  The present invention has been made to solve the above-described problem, and can improve the distance resolution of a target and can display a radar image without the possibility of misidentifying the distance to the target. An object is to provide a radar apparatus.

  A radar apparatus according to the present invention is a radar apparatus that separates and displays a radar image of a target in a distance direction, a receiving unit that receives a radar echo reflected by the target, and the predetermined range set in the distance direction. The maximum value of the radar echo is calculated, and the value of the radar echo on the separated side is corrected based on the difference between the maximum value and the value of the radar echo on the side separated from the radar device within the predetermined range. And a signal processing unit that performs processing, and displays a radar image based on the corrected radar echo.

In the radar apparatus, the signal processing unit is configured to output the radar echo.
S _i = V _i −K × {max (V _i−d : V _i ) −V _i } ^e
S _i: Output data V _i after correction of the radar echo: Input data V _i-d before correction of the radar echoes: the input data _{V i} the input data previously acquired d items only from max _{(V i- d} : V _i ): maximum value from the input data V _i-d to the input data V _i K: coefficient e: corrected as an exponent.

  In the radar apparatus of the present invention, when shaping the waveform of the radar echo reflected by the target, the waveform on the side close to the radar apparatus is not shaped, and only the waveform on the side away from the radar apparatus is close to the radar apparatus. Shape as follows. As a result, the distance resolution of the target can be increased, and the distance to the target is not affected by the waveform shaping, so that it is possible to display a radar image without the possibility of misidentifying the distance to the target. it can.

1 is a configuration block diagram of a radar apparatus according to an embodiment of the present invention. It is a block diagram of the waveform shaping circuit with which the signal processing part in FIG. 1 is equipped. It is explanatory drawing of the radar echo before and behind the shaping process by the waveform shaping circuit shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a radar apparatus 10 according to an embodiment of the present invention.

<Description of Configuration of Radar Device 10>
The radar device 10 is a device that transmits a radar signal, receives a radar echo reflected by a target such as a ship or an aircraft, displays a radar image, and monitors the direction of the target and the distance to the target. is there. The radar apparatus 10 includes an antenna 12, a transmission / reception unit 14 (reception unit), an A / D conversion unit 16, a signal processing unit 18, a coordinate conversion unit 20, a radar echo storage unit 22, a display control unit 24, and a display unit 26.

  The transmission / reception unit 14 transmits a radar signal via the antenna 12 and receives a radar echo reflected by the target. The A / D converter 16 converts the radar echo into a digital signal. The signal processing unit 18 processes the radar echo and performs signal processing to acquire a desired radar echo. The coordinate conversion unit 20 converts the radar echo in the polar coordinate format converted into the digital signal into the radar echo in the orthogonal coordinate format. A radar echo including azimuth information and distance information is drawn in the radar echo storage unit 22. The display control unit 24 performs control to display the radar image of the target on the display unit 26 based on the radar echo drawn in the radar echo storage unit 22. The display unit 26 displays a radar image based on the control of the display control unit 24.

  FIG. 2 is a block diagram of the waveform shaping circuit 28 provided in the signal processing unit 18 in FIG. The waveform shaping circuit 28 is a circuit that performs radar echo waveform shaping processing in order to increase the resolution in the distance direction, and includes a parameter setting unit 30, a maximum value calculation unit 32, a difference indexing unit 34, and a distance direction correction unit 36. Prepare.

  The parameter setting unit 30 sets the reference data number d, the index e, and the coefficient K, which are parameters for waveform shaping. The maximum value calculation unit 32 calculates the maximum value of the radar echo in a predetermined range set in the distance direction supplied from the A / D conversion unit 16. The difference indexing unit 34 calculates a difference index value obtained by raising the difference between the maximum value and the radar echo value on the side away from the radar apparatus 10 by a predetermined range by the set index e. The distance direction correction unit 36 corrects the value of the radar echo on the side away from the radar apparatus 10 based on the calculated difference index value and the set coefficient K, and calculates the radar echo with improved distance direction resolution. To do.

<Description of Processing of Radar Device 10>
Next, processing of the radar apparatus 10 will be described.

  The transmission / reception unit 14 oscillates a magnetron (not shown) and transmits a radar signal toward the target via the antenna 12. The radar signal is reflected by the target and is received as a radar echo by the transmission / reception unit 14 via the antenna 12. The radar echo received by the transmission / reception unit 14 is converted into a digital signal by the A / D conversion unit 16 and supplied to the signal processing unit 18. The radar echo supplied to the signal processing unit 18 is subjected to waveform shaping processing by the waveform shaping circuit 28.

In the waveform shaping circuit 28, the input data V _i that is a radar echo is processed according to the following equation (1), and the waveform-shaped output data S _i is calculated.

S _i = V _i −K × {max (V _i−d : V _i ) −V _i } ^e (1)

Here, the input data V _i is the i-th input data input to the waveform shaping circuit 28. The input data V _i-d is input data that is input by the reference data number d before the input data V _i . The index e and the coefficient K are parameters for shaping so as to narrow the width of the radar echo waveform. These parameters can be set according to the pulse width of the radar signal transmitted from the transmission / reception unit 14 via the antenna 12. The parameters of the reference data number d, the index e, and the coefficient K are set in the parameter setting unit 30 by the operator in advance. The maximum value max (V _i−d : V _i ) is input data having the maximum electric field strength selected from the (i−d) -th to i-th input data V _{i-d to} V _i .

Maximum value calculating unit 32 in accordance with reference data number d from the parameter setting unit 30, A / D input data supplied from the converting unit 16 _{V i-d} ~V _i maximum value _max of the _{(V i-d: V i} ) Is calculated. The difference indexing unit 34 uses the input data V _i , the calculated maximum value max (V _i−d : V _i ), and the index e from the parameter setting unit 30 to calculate the difference index value {max (V _i−d : V _i ) −V _i } ^e is calculated. The distance direction correction unit 36 uses the input data V _i , the calculated difference index value {max (V _i−d : V _i ) −V _i } ^e, and the coefficient K from the parameter setting unit 30, (1) calculating the output data S _i obtained by correcting the input data V _i based on the equation.

  FIG. 3 is an explanatory diagram of radar echoes before and after the shaping process by the waveform shaping circuit 28 shown in FIG.

  A portion A1 where the electric field strength of the radar echo increases and a portion A2 where the electric field strength decreases are radar echoes by the first target before shaping. A portion B1 where the electric field strength of the radar echo increases and a portion B2 where the electric field strength decreases are radar echoes by the second target before shaping. The first target is closer to the radar device 10 than the second target. When the first target and the second target are close to each other, the radar echoes before shaping are the maximum values of the electric field strengths of the portions A1, A2 and B1, B2 (values of the points P1, P2) and the portion A2. Since the difference between the minimum value of the electric field intensity between B1 and the value of the point P3 is small, it is difficult to identify the first target and the second target separately.

On the other hand, the radar echo portions A3 and A4 are radar echoes by the first target after shaping based on the equation (1), and the portions B3 and B4 are radar echoes by the second target after shaping. is there. In this case, in the range where the electric field strength of the radar echo specified by the reference data number d increases,
max (V _i-d : V _i ) = V _i
Therefore, the output data S _i in this range is obtained from the equation (1):
S _i = V _i
It becomes. Therefore, in this range, the radar echo portions A1 and A3 of the first target close to the radar device 10 and the radar echo portions B1 and B3 of the second target close to the radar device 10 are shaped. It does not change before and after processing.

On the other hand, in the range where the electric field intensity of the radar echo defined by the reference data number d decreases,
max (V _i-d : V _i ) = V _i-d
Therefore, the output data S _i in this range is obtained from the equation (1):
S _i = V _i −K × (V _i−d −V _i ) ^e
It becomes. Therefore, in this range, the radar echo portion A2 of the first target that is separated from the radar device 10 and the radar echo portion B2 of the second target that is separated from the radar device 10 are portions A4 in which the electric field strength is weakened. And the portion B4 are respectively subjected to the shaping process.

  As a result, the shaped radar echo output from the waveform shaping circuit 28 is not affected by the shaping process because the distance to the first target and the second target on the side close to the radar apparatus 10 is not affected. It is possible to detect without misidentifying the positions of the first target and the second target with respect to 10. Note that the distance from the radar device 10 to the first target and the second target approaches the radar device 10 side by the shaping process, but the positions of the first target and the second target are detected. Will not be a problem.

  Further, as shown in FIG. 3, the minimum value of the electric field strength between the portions A2 and B1 before the shaping process (the value of the point P3) is the minimum value of the electric field strength between the parts A4 and B3 by performing the shaping process. It greatly decreases to (the value of the point P4). Therefore, the resolution in the distance direction is increased, and the radar echo by the first target and the radar echo by the second target can be easily separated and identified.

  The radar echo shaped as described above is converted from the polar coordinate format to the orthogonal coordinate format by the coordinate conversion unit 20 and then drawn in the radar echo storage unit 22. Next, the display control unit 24 reads out the radar echo drawn in the radar echo storage unit 22 and displays it on the display unit 26 as a radar image. In this case, as shown in FIG. 3, the radar echo is displayed after the waveform is shaped, so that it is possible to obtain a high resolution in the distance direction and a radar image that does not misidentify the distance to the target. Can be obtained.

  In addition, this invention is not limited to embodiment mentioned above, It is possible to change in the range which does not deviate from the main point of this invention.

DESCRIPTION OF SYMBOLS 10 ... Radar apparatus 12 ... Antenna 14 ... Transmission / reception part 16 ... A / D conversion part 18 ... Signal processing part 20 ... Coordinate conversion part 22 ... Radar echo memory | storage part 24 ... Display control part 26 ... Display part 28 ... Waveform shaping circuit 30 ... Parameter setting unit 32 ... maximum value calculating unit 34 ... difference indexing unit

Claims (2)

In a radar device that displays a radar image of a target separately in the distance direction,
A receiver for receiving radar echoes reflected by the target;
The maximum value of the radar echo in a predetermined range set in the distance direction is calculated, and based on the difference between the maximum value and the value of the radar echo on the side remote from the radar device in the predetermined range, the separating side A signal processing unit for performing processing for correcting the value of the radar echo of
And a radar image based on the corrected radar echo. The radar apparatus according to claim 1, wherein
The signal processing unit, the radar echo,
S _i = V _i −K × {max (V _i−d : V _i ) −V _i } ^e
S _i: Output data V _i after correction of the radar echo: Input data V _i-d before correction of the radar echoes: the input data _{V i} the input data previously acquired d items only from max _{(V i- d} : V _i ): Maximum value from the input data V _i-d to the input data V _i K: Coefficient e: Corrected as an exponent.

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