JP2001194455A - Radar signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a signal processor which can obtain a high-resolution image by extracting only an imaging indication position, when a plurality of targets exist. SOLUTION: First, all data are cut out at a data cutting-out part, and range addition is performed conforming to resolution at a range addition part. A phase compensating part performs phase compensation by using set resolution and vibrating data. An azimuth compression part performs processing by using the set resolution and the vibrating data. A second display part performs log transformation of output data of a detection part and displays the results. Concerning a target confirmed by the second display part, imaging indication of high resolution is performed, and a target position and resolution are outputted to a parameter operating part, which operates parameter, such as the number of range bins and the number of pulses from the target position, the resolution, the vibrating data and a target size as the output of the target detecting part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar apparatus for a synthetic aperture radar mounted on a flying object such as an aircraft.

[0002]

2. Description of the Related Art FIG. 7 shows, for example, Merrill Sko
1 is a configuration block diagram of a conventional synthetic aperture radar processing apparatus shown in Radar Handbook by Innik. In FIG. 7, 1 is received data, 2 is a signal processing unit, 3
Is a range compression unit, 4 is a memory unit, 5 is a phase compensation unit, 6 is fluctuation data, 7 is an azimuth compression unit, 8 is a detection unit, and 9 is a display unit.

Next, the operation will be described. Receive data 1
Is a reflected wave transmitted from the synthetic aperture radar to the observation region, where the pulse-modulated signal is transmitted. The reception data 1 is compressed by the range compression unit 3 to increase the resolution in the range direction. Then, the memory unit 4 stores pulse data for the synthetic aperture time. The number of pulses is obtained by Equation 1.

[0004]

(Equation 1)

In equation (1), a method for improving the azimuth resolution by stabilizing an antenna beam toward a target is considered. In Equation 1, θ is the synthetic aperture angle, λ is the wavelength, Δr is the resolution, ψ is the squint angle, R is the distance from the own machine to the target, r is the synthetic aperture length, V is the own machine speed, PRI
Is the pulse repetition interval. These geometries are shown in FIG. In FIG. 8, A is the position of the own device, and B is the target imaging area.

Next, the phase compensator 5 performs phase compensation for compensating for a phase shift from the flight path using the momentary data 6 such as the velocity, x, y, and z positions representing the motion of the aircraft. Then, the azimuth compression unit 7 performs compensation in the azimuth direction while compensating for the distance deviation from the flight path using the fluctuation data 6. The detection unit 8 performs square detection, and the display unit 12 performs log conversion to display a two-dimensional image.

[0007]

Since the conventional radar signal processing apparatus is configured as described above, there is a problem that the amount of data processing becomes large when an image with high resolution is obtained.

Further, there is a problem that the processing time becomes long when an image with a high resolution is obtained.

In addition, when an image with a high resolution is obtained, there is a problem that the target cannot be continuously irradiated with radio waves because the synthetic aperture time is long.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and detects a target in a low-resolution image, and then performs high-resolution image reproduction processing only in an area where the target exists to expand a wide area. It is an object of the present invention to obtain a radar signal processing device that reduces the amount of data processing compared to processing with high resolution.

Further, the present invention performs display by performing signal processing at a low resolution and then performs signal processing at a high resolution only in an area where the target exists, so that necessary target information can be obtained in a short time in a high-resolution image. An object of the present invention is to obtain a radar signal processing device that can be obtained.

Further, according to the present invention, signal processing is performed at a low resolution and displayed, and then control of a flight path, control of an antenna, and control of a gate are performed based on necessary resolution and position information of a target, and radio waves are transmitted to the target. It is an object of the present invention to obtain a radar signal processing device capable of acquiring data by continuously irradiating the image and imaging the image.

[0013]

A radar signal processing apparatus according to a first aspect of the present invention uses a transmission signal (chirp signal) subjected to frequency modulation by an ordinary transmitter to pulse received data output from a receiver. A range compression section for performing compression, a memory section for buffering output data of the range compression section, a phase compensation section for performing phase compensation for output data of the range addition section by using the motion data of the aircraft, and output data of the phase compensation section And an azimuth compression unit for performing azimuth compression on the basis of the above-mentioned fluctuation data.
A detection section for performing multi-detection is provided with a data cutout section for cutting out data for the data in the memory section, a range addition section for performing range addition for the output of the data cutout section, and a target position and a target for power data output from the detection section. A target detection unit for obtaining a size, and a parameter calculation unit for calculating a signal processing parameter using the target position and the target size output from the target detection unit and the above-mentioned fluctuation data are provided.

Further, the radar signal processing apparatus according to the second aspect of the present invention processes a normal range compression section, a memory section, a phase compensation section, an azimuth compression section, a detection section, and output data of the detection section at first with a low resolution. Display image data,
Next, a display section for displaying high-resolution image data on a target is provided with the data cutout section, the range addition section, the target detection section, and the parameter calculation section.

Further, the radar signal processing apparatus according to the third aspect of the present invention is a radar signal processing apparatus in which the data cutout section, the range addition section, and the target detection section are provided in a normal range compression section, a memory section, a phase compensation section, an azimuth compression section, and a detection section. A second display unit for displaying output data of the detection unit and setting an imaging position and a resolution; signal processing based on output data of the second display unit, output data of the target detection unit, and sway data And a second parameter calculation unit for obtaining a parameter for use.

A radar signal processing apparatus according to a fourth aspect of the present invention comprises a normal antenna unit, a transmission / reception switching unit, a transmission unit, a reception unit,
An A / D converter, a signal processing unit, the target detection unit, a second display unit for inputting an observation position by an operator, and parameters obtained from output data of the display unit, the sway data, and an output of the target detection unit. A second parameter calculation unit, a flight control unit that controls a flight path so that the beam hits the observation position by using the output of the second parameter, and a center of the beam is set to the observation position output from the display unit. And an antenna control unit for controlling an antenna, and a gate control unit for changing a gate to an observation position which is an output of the display unit.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention. In FIG. 1, a signal processing unit 2, a range compression unit 3, a memory unit 4, a phase compensation unit 5, an azimuth compression unit having the same configuration as the conventional example of FIG. Since the section 6 and the detection section 8 have already been described, the description is omitted here. Reference numeral 10 denotes a target detection unit, 11 denotes a parameter calculation unit, 12 denotes a data cutout unit, and 13 denotes a range addition unit.

Next, the operation will be described. First, the target for resolution [Delta] r _t for processing a wide area processing resolution [Delta] r _w and the target for finding the target to the parameter calculation unit 11 with high resolution. In the first time, all data is cut out by the data cutout unit 12 as shown in Expression 2.

[0019]

(Equation 2)

In Equation 2, R is the ratio between the resolution for wide-area processing and the resolution for target, x and y are the center coordinates of the image, and x = y in the first time.
0, y = 0. Din (i, j) indicates data before data extraction, D (i, j) indicates data after data extraction, i indicates a range bin number, and j indicates a pulse number. M is the number of range bins, and N is the number of pulses. Next, as shown in Expression 3, the range addition unit 13 performs range addition in accordance with the resolution for wide area processing and the resolution for target.

[0021]

(Equation 3)

In the equation (3), R is the ratio between the resolution for wide-area processing and the resolution for target, D (i, j) is the data before range addition,
Dadd (i, j) indicates data after range addition, i indicates a range bin number, and j indicates a pulse number. The processes from the phase compensation unit 5 to the detection unit 8 perform the same processing as the conventional example. Target detection unit 1
If the value is 0, the maximum value is detected, and the data is binarized according to Equation 4.

[0023]

(Equation 4)

Here, Ci and j are i range bins, power value data of j pulses, and S is a threshold. As shown in FIG. 2, the range size x and the azimuth size y are determined, and the image center position c is determined. Using these and the target resolution, the parameter calculation unit 11 calculates signal processing parameters. For example, for the number of pulses,
The obtained by performing a re-calculation as Δr _t. Then, signal processing for the target area is performed. Use the same resource as the first time. The data cutout unit 12 cuts out the range according to Equation 2. As shown in Equation 5, the phase compensator 5 compensates for the phase shift amount Δφ from the image center position c and the flight path using the fluctuation data 6 which changes every moment such as the position indicating the fluctuation of the airframe. The azimuth compression unit 7 uses the motion data 6 to compensate for the distance deviation from the flight path and to perform azimuth compression.

[0025]

(Equation 5)

In equation (5), Δφ is the phase of the deviation from the image center position and the flight path, dR is the deviation from the image center position c and the ideal flight path, and dr is the distance from the own position and the ideal flight path. Indicates the amount of deviation. Also, dR +
dr is the distance shift amount. The detector 8 performs the same processing as the first time. In this way, high-resolution image processing data is obtained only for the point where the target exists.

Embodiment 2 FIG. FIG. 3 is a block diagram showing the configuration of a second embodiment of the present invention. In FIG. 3, a range compressor 3, a memory 4, a phase compensator 5, an azimuth compressor 6, and a detector having the same configuration as the conventional example of FIG. 8 has already been described, and the description is omitted here. 9 is a display unit,
Reference numeral 10 denotes a target detection unit, 11 denotes a parameter calculation unit, and 12 denotes a data cutout unit.

Next, the operation will be described. First, the parameter calculation unit 11 sets a wide-range processing resolution for finding a target and a target resolution for processing the target with high resolution. In the first time, all data is cut out by the data cutout unit 12, and the range addition unit 13 performs range addition according to the wide area processing resolution. The phase compensator 5 to the detector 8 perform the same processing as the conventional example. The display unit 9 performs log conversion of the output data of the detection unit 8 and displays the result. Considering the data processing amount, for example, the data processing amount of the azimuth compression unit is represented by Expression 6.

[0029]

(Equation 6)

Here, C is a complex multiplication number, F is an FFT number, M
Is the number of ranges to be processed, and N is the number of pulses to be processed. The data processing amount is proportional to the number of ranges and the number of pulses, respectively, but is inversely proportional to the resolution as shown in Equation 1. For example, if the resolution for wide-area processing is 64 m and the resolution for target processing is 1 m, and the same area is processed,
It is processed and displayed in 1/096 of the time. On the other hand, the target detecting section 10 detects the maximum value, binarizes the target by the equation 2, estimates the target size, and determines the image center position from the range size x and the azimuth size y. A parameter for signal processing is obtained by parameter calculation 11 based on the range size x, the image center position c, and the target resolution, and the second signal processing is started. The data extraction unit 12 extracts a range. The number of pulses is obtained by recalculating using Equation 1. The phase compensator 5 performs phase compensation using the range obtained from the fluctuation data 6 and the image center position c. The azimuth compression unit 7 also obtains a reference from the motion data 6 and the image center position c and performs azimuth compression. The detection unit 8 performs the same processing as the first time. The display unit 9 displays high-resolution image data only at the point where the target exists. For example, when observing an area of 10 km ² at the above resolution and the target size is 200 m ² , it is possible to obtain detailed target information about 200 times faster than displaying high-resolution image data at one time. it can.

Embodiment 3 FIG. 4 is a block diagram showing the configuration of a third embodiment of the present invention. In FIG. 4, a range compressor 3, a memory 4, a phase compensator 5, an azimuth compressor 7, and a detector having the same configuration as the conventional example of FIG. 8 has already been described, and the description is omitted here. 10 is a target detection unit, 12 is a data cutout unit, 13 is a range addition unit,
Reference numeral 14 denotes a parameter calculation unit, and 15 denotes a second display unit.

Next, the operation will be described. First, the second parameter calculation unit 14 sets a wide-area processing resolution for finding a target. The first time is the data extraction unit 12
Then, all data are cut out, and the range addition unit 13 performs range addition according to the resolution. The phase compensator 5 performs the phase compensation using the set resolution and the sway data 6. The azimuth compression unit 7 performs processing using the set resolution and the fluctuation data 6. In the second display unit 15, the output data of the detection unit 8 is log-converted and displayed. Second
A high-resolution imaging instruction is given for the target confirmed on the display unit 15 of the above, and the target position and the resolution are determined by the parameter calculation unit 1.
4 is output. The parameter calculation unit 14 calculates parameters such as the number of range bins and the number of pulses from the target position, the resolution, the fluctuation data 6, and the target size output from the target detection unit 10. The number of range bins is calculated by Equation 7, and the number of pulses is calculated by Equation 1.

[0033]

(Equation 7)

The number M in 7 range bins number, Sx is range direction target size, [Delta] r _s denotes the range sample interval. In the case of an imaging instruction, a plurality of imaging positions are set, for example, when there are a plurality of targets as shown in FIG. 5, and imaging priority items such as an instruction order, an order of a larger target size, and an order of a closer range are added. The parameter calculation unit 14 sorts according to priority items and calculates parameters for each target.
From the second time on, the signal processing is performed for the designated target number in accordance with the parameters calculated by the parameter calculation unit 14. Thus, even if there are a plurality of targets, the imaging order can be designated according to the purpose, and a high-resolution image can be displayed.

Embodiment 4 FIG. FIG. 6 is a block diagram showing the configuration of a fourth embodiment of the present invention. In the figure, 16 is an antenna unit, 17 is a transmission unit, 18 is a transmission / reception switching unit, 19 is a reception unit, 6 is fluctuation data, and 20 is A / A A D conversion unit, 2 is a signal processing unit, 10 is a target detection unit, 15 is a second display unit, 14 is a parameter calculation unit, 21 is a flight control unit, 22 is an antenna control unit, and 23 is a gate control unit.

Next, the operation will be described. Antenna part 1
6, the transmission unit 17, the transmission / reception switching unit 18, and the reception unit 19 are conventional ones. Radio waves are radiated from the antenna unit 19 via the transmission / reception switching unit 18 in response to a transmission signal from the transmission unit 17. Further, the radio wave received by the antenna unit 16 passes through the transmission / reception switching unit 18 and is gated by the reception unit 19 in accordance with the gate control unit 23. The received signal output from the receiving unit 19 is A
The signal is converted from an analog signal to a digital signal by the / D converter 20 and input to the signal processor 2. Signal processing unit 2, 1
0 is omitted because the target detection unit, the second display unit 15, and the fluctuation data 6 have already been described.

The second parameter calculator 14 calculates a squint angle from the target position, the resolution, and the sway data 6 output from the second display unit 15. Here, it is simplified and projected two-dimensionally as shown in FIG. The flight direction is controlled according to Equation 8 from the squint angle and the threshold angle.

[0038]

(Equation 8)

Here, ψ is a squint angle, ψ0 is a threshold angle, and Δθ is an angle to be changed from the current flight direction. The flight control unit 21 controls the flight in accordance with the flight direction output from the second parameter calculation unit 14. The second parameter calculator 14 outputs an antenna angle at which the beam center coincides with the target center to the antenna controller, and outputs a gate position to the gate controller so that the target enters the gate. In this way, the target is kept irradiated with the radio wave during the synthetic aperture time.

[0040]

According to the first aspect of the present invention, only the necessary area is processed with high resolution, so that the amount of data processing can be reduced.

According to the second aspect, a wide area can be displayed in a short time, a high-resolution image can be displayed by extracting only a target, and data used for a wide area can be used. .

According to the third aspect of the present invention, a wide area can be displayed in a short time to find a target, and even when there are a plurality of targets, only a designated imaging position can be extracted to obtain a high-resolution image. .

Further, according to the fourth aspect of the present invention, even if the synthetic aperture time is long, it is possible to continuously irradiate a beam during data acquisition to acquire data and image it.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a first embodiment of a radar signal processing device according to the present invention;

FIG. 2 is a conceptual diagram of a target detection unit 10;

FIG. 3 is a diagram showing a second embodiment of the radar signal processing device according to the present invention;

FIG. 4 is a diagram showing a third embodiment of the radar signal processing device according to the present invention;

FIG. 5 is a conceptual diagram in which an imaging instruction is issued on a second display unit 15;

FIG. 6 is a diagram illustrating a fourth embodiment of a radar signal processing device according to the present invention;

FIG. 7 is a diagram of a conventional radar signal processing device.

FIG. 8 is a diagram showing a positional relationship between the own device and a target image area.

[Explanation of symbols]

1 received data, 2 signal processing section, 3 range compression section,
4 memory unit, 5 phase compensation unit, 7 azimuth compression unit,
8 detection section, 9 display section, 10 target detection section, 11 parameter calculation section, 12 data cutout section, 13 range addition section, 14 second parameter calculation section, 15 second display section, 16 antenna section, 17 transmission section , 18 transmission / reception switching unit, 19 reception unit, 20 A / D conversion unit, 21 flight control unit, 22 antenna control unit, 23 gate control unit.

Claims (4)

[Claims] 1. A radar signal processing apparatus for a synthetic aperture radar mounted on a flying object, using a transmission signal (chirp signal) subjected to frequency modulation by a transmitter to pulse received data output from a receiver. A range compressing unit for performing compression, a memory unit for buffering output data of the range compressing unit, a data extracting unit for extracting data from the memory unit, a range adding unit for performing range addition on the output of the data extracting unit, and the range A phase compensator for performing phase compensation using the body motion data for the output data of the adder, an azimuth compressor for performing azimuth compression using the output data of the phase compensator and the motion data, and output data of the azimuth compressor. , A detector that performs square-law detection on the power data output from the detector, A radar signal comprising: a target detection unit for obtaining a target size; and a parameter calculation unit for calculating a signal processing parameter using the target position and the target size output from the target detection unit and the sway data. Processing equipment. 2. A display unit for displaying image data processed at a low resolution with respect to output data of the detection unit, and then displaying high-resolution image data for a target. 2. The radar signal processing device according to claim 1. 3. A second display unit for displaying output data of the detection unit and setting an imaging position and a resolution.
A signal processing parameter for obtaining a signal processing parameter from the output data of the display unit, the output data of the target detection unit, and the sway data.
2. The radar signal processing apparatus according to claim 1, further comprising: a parameter calculation unit. 4. A second display unit for displaying an output of the detection unit and for inputting an observation position by an operator, and for obtaining a parameter from output data of the display unit, the sway data and an output of the target detection unit. A flight control unit that controls the flight path so that the beam hits the observation position by using the output of the second parameter; and an antenna such that the center of the beam comes to the observation position that is the output of the display unit. 2. The radar signal processing apparatus according to claim 1, further comprising an antenna control unit for controlling a signal, and a gate control unit for changing a gate at an observation position which is an output of the display unit.