JPH1078481A - Aircraft loaded radar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct a synthetic aperture radar (SAR) signal process and a moving target detecting process without lowering resolution, detecting distance performance and signal processing speed from one transmission signal by controlling a sampling frequency by an azimuth direction presuming process and limiting a band by a range direction presuming process. SOLUTION: A signal is transmitted from a transmitter 2 via a monopulse antenna 16. A reflection signal from a target is received by the antenna 16, Σsignal and Δ signal are transmitted to a receiver 5, amplified and phase- detected. An azimuth direction presuming processor 17 lowers a sampling frequency of a reception signal, and reduces data to PRF (pulse repetition frequency) necessary for an SAR imaging process. A range direction presuming processor 18 limits a band, lowers range resolution, and prevents a target signal from being divided. Further, an SAR signal process and a moving target detecting process are functioned in parallel. After amplitude detection of a detector 14 is conducted, a target is detected by a target detector 21 by using the Σ signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar mounted on an aircraft which improves the resolution in the azimuth direction by improving the resolution in the range direction by pulse compression, and synthesizing the aperture surface of the antenna by the movement of its own device. .

[0002]

2. Description of the Related Art FIG. 9 is a view showing the configuration of a conventional radar apparatus for on-board an aircraft. In FIG. 9, reference numeral 1 denotes an exciter for generating a continuous wave having a constant frequency, and 2 denotes a signal output from the exciter. Amplify and maintain a constant pulse repetition frequency (Pulse Rep)
A transmitter for transmitting a signal by etion frequency (PRF), 3 is a transmission / reception switch for switching between transmission and reception, 4 is an antenna that emits a signal toward a target, and an antenna that receives a reflected signal thereof, 5 is a received signal 6 is a pulse compressor that demodulates the modulated signal to generate a narrow pulse, and 7 is a range movement correction that corrects a change in distance caused by a target movement of the signal after the pulse compression. A processor 8, an inertial reference device 8 for sensing the movement and shaking of the own machine, a buffer memory 9 for storing data after range movement correction, and a fast Fourier transform (10) for processing data read from the buffer memory. Fast Fourier Transform:
An FFT (calculation unit) 11 is a reference function creator that creates a reference function for performing azimuth compression processing based on the movement and vibration data of the own device output from the inertial reference device 8.
2 is a complex multiplier for performing complex multiplication of the result after the FFT processing and the reference function, and 13 is an inverse fast Fourier transform (Inverse FFT: hereinafter IFF) for processing the result after the complex multiplication.
T) a computing unit, 14 is a detector for detecting the amplitude of the result of the IFFT processing, and 15 is a multi-look processing unit for adding a synthetic aperture radar image after detection in order to reduce speckle noise.

Next, the operation will be described. An exciter 1 generates a signal that has been frequency-modulated with a constant PRF,
The signal is amplified and phase-detected by the transmitter 2. This signal is radiated from the antenna 4 toward the target via the transmission / reception switch 3. The signal reflected from the target is received by the antenna 4 and amplified and phase-detected by the receiver 5. In the pulse compressor 6, the frequency-modulated signal is demodulated, and a narrow pulse is generated. Thereby, the observation region is finely decomposed in the range direction. The range movement correction processor 7 corrects a change in distance to a target caused by the movement of the own device, that is, a range movement, based on the movement and shaking data of the own device output from the inertial reference device 8. The corrected data is stored in the buffer memory 9, and when data necessary for performing FFT is stored, the data is output to the FFT calculator 10. The reference function creator 11 creates a reference function based on the movement and motion data of the own device from the inertial reference device 8. The complex multiplier 12 multiplies the created reference function by the complex multiplier 12 with the data after the FFT processing performed by the FFT calculator 10. The result of the complex multiplication is subjected to IFFT processing in the IFFT calculator 13 and compression in the azimuth direction is performed. The data after the azimuth compression is amplitude-detected by the detector 14 to generate an image. The generated images are superimposed by a multi-look processor 15 in order to reduce speckle noise, and a high-resolution synthetic aperture radar (Synthe) is used.
tic Aperture Radar: SAR)
Output as an image.

[0004]

A conventional radar apparatus for mounting on an aircraft for creating a synthetic aperture radar image is constructed as described above, and performs correction by moving and swaying its own aircraft to obtain a high resolution of a fixed target. It is possible to create an image. However, when the moving target exists as shown in FIG. 10A, the Doppler frequency shifts as shown in FIG. 10B. FIG. 11 shows the influence on the SAR image at this time. When the Doppler frequency is shifted as shown in FIG. 11 (a), multiplying by the reference function shown in FIG. 11 (b) results in a moving target with respect to its own speed as shown in FIG. 11 (c). Misalignment occurs. In addition, since the moving speed of the target is not constant in practice, the Doppler frequency has a spread, and the image is blurred when the image processing is performed. Thus, by the Doppler frequency generated by the movement of the target,
If the position of the target is shifted or the image is blurred, and the target Doppler frequency is wider than the band of the radar, aliasing occurs on the frequency axis and there is a problem that imaging cannot be performed. Further, even when the moving target detection processing is performed, the PRF used in the signal processing of the SAR and the PRF necessary for detecting the moving target are greatly different, and therefore, the processing cannot be performed using the same signal.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and detects a moving target in an SAR.
The purpose is to calculate the position and display the moving target on the SAR image.

In addition, the present invention uses the result of the detection of a moving target, so that the inverse synthetic aperture radar (Inverse SA) of the moving target can be used with almost no change in the components.
R: hereinafter referred to as an ISAR) image.

Another object of the present invention is to convert coordinates in the cross-range direction represented by the Doppler frequency of an ISAR image of a moving target into a distance.

Further, the present invention provides an X-band radar capable of obtaining an antenna size and a PRF realizing a performance of 3 m resolution with multi-look [Equation 3] to [Equation 4] in an own vehicle speed of 170 to 190 m / s. The purpose is.

Another object of the present invention is to mount a large antenna without interfering with the body of the vehicle by radio waves.

[0010]

According to a first aspect of the present invention, there is provided a radar apparatus mounted on an aircraft for detecting a moving target by using a PRF.
For the signal transmitted by increasing the azimuth direction presum processor to lower the receiver and sampling frequency,
Performs signal processing to create a high-resolution image. At the same time, a range direction presum processor for limiting the band of the received signal to lower the resolution is provided so that the target reflected signal is not decomposed. In addition, a monopulse antenna that outputs a Σ signal and a Δ signal of a received signal, and performs pulse compression, clutter suppression,
An arithmetic unit for performing frequency analysis and detection is provided.モ ノ Monopulse calculation is performed on the moving target detected using the signal to calculate the angle. From the calculated angle, set the moving target to SAR
An arithmetic unit for superimposing and displaying the image on the image is provided.

[0011] The radar device mounted on an aircraft according to the second aspect of the present invention calculates the Doppler frequency of the moving target based on the detected Doppler frequency.
A range shift correction processor and a Doppler correction processor for calculating and correcting the target range shift amount and Doppler change amount are provided, and a frequency analyzer and a detector are provided for creating a two-dimensional image of the moving target. .

[0012] A third aspect of the present invention provides an airborne radar apparatus comprising: a monopulse antenna for outputting a Σ signal and a Δ signal of a received signal; and a range movement correction processor for processing each of the Σ signal and the Δ signal. , A Doppler correction processor, a frequency analyzer, and a detector, and the angle detector determines the angle of two points in the ISAR image of the moving target. The cross-range direction of the ISAR image is distanced from the Doppler frequency based on the angle. Is provided with a coordinate converter for converting into.

[0014] In addition, the radar device for on-aircraft according to the fourth invention has two antennas arranged side by side, and a signal received from each antenna is subjected to a presum processor, a pulse compression processor, a clutter suppression processor, a frequency analyzer, A detector and a target detector are provided to detect a target. An arithmetic unit for obtaining a target angle from a target phase detected by the two signals is provided. Similarly, a range shift correction processor, a Doppler correction processor, a frequency analyzer, and a detector are provided for two signals, and two ISAR images are created. Two ISAs
An arithmetic unit for calculating the angle of each target point from the R image is provided, and the Doppler frequency component of the ISAR image is converted into a distance.

Further, the aircraft-mounted radar device according to the fifth invention uses an X-band frequency, uses an antenna of 1.5 m to 2 m, sets a PRF at the time of transmission to 2000 Hz or more,
After reception, when performing high-resolution imaging processing, presum processing is performed, and the rate after resampling is set to 260 to 380 Hz.

Further, in the radar apparatus for onboard aircraft according to the sixth invention, the angle に 対 す る from the antenna boresight direction to the edge located at the shortest distance of the aircraft's own body is 1/1 / the beam width.
Two or more antennas are mounted on the upper or lower part of the fuselage horizontally.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a block diagram showing a first embodiment of the present invention. In FIG. 1, reference numerals 1 to 3 and 5 to 15 are the same as those of the conventional apparatus. Reference numeral 16 denotes a monopulse antenna for performing transmission and reception. The azimuth direction presum processor 17 resamples the data sampled at the PRF necessary for detecting the moving target to the PRF necessary for performing the SAR processing. 18
Is a range direction presum processor for limiting the frequency modulation band applied to create a SAR image with high resolution to a band corresponding to the resolution required for moving target detection. Reference numeral 19 denotes a clutter suppression processor which reduces a reflected signal from a fixed target. 20
Is a frequency analyzer that detects the Doppler frequency of the moving target by FFT processing (performs the same operation as the 10 FFT calculators). 21 is a constant false alarm probability (CF
AR) is a target detector for detecting a target. Reference numeral 22 denotes a target position corrector which calculates a correct position of a target displayed offset on the SAR image. 2
Reference numeral 3 denotes a superposition processor, which superimposes and displays a target symbol on the SAR image.

Next, the operation will be described. The signal output from the transmitter 2 is transmitted to the outside by the monopulse antenna 16. Further, the reflected signal from the target is received by the same monopulse antenna 16. After the reception, the two signals of the Σ signal and the Δ signal are sent to the receiver 5, where they are amplified and phase-detected. FIG. 2A shows the relationship between the amplitudes of the Σ signal and the Δ signal. The signal Σ is sent to the SAR imaging process. Both the Σ signal and the Δ signal are sent to the moving target detection processing. To detect the velocity of a moving target, the radar PRF
Must be greater than the target Doppler frequency. Therefore, it is necessary to increase the PRF in the moving target detection processing. However, when the PRF is increased, S
The amount of data handled in the AR imaging processing increases, and the processing cannot be completed within the data collection time. Therefore, the azimuth direction presum processor 17 lowers the sampling frequency of the received signal and performs processing to reduce the data to the PRF required for SAR imaging processing. With respect to the SAR imaging processing thereafter, the same processing as that of the conventional apparatus is performed. In addition, if the processing for increasing the resolution in the range direction is performed in the moving target detection processing, a reflected signal from a target larger than the resolution is divided in the range direction, the reflected power is reduced, and the detection distance is reduced. .
Therefore, band limitation is performed in the range direction presum processor 18 to reduce the range resolution and prevent the target signal from being divided. Also, by making the SAR signal processing and the moving target detection processing function in parallel as shown in FIG.
The moving target detection processing is performed during the AR signal processing time. Then, the signal after the presum processing passes through 6 pulse compressors,
A narrow pulse (which is wider than the narrow pulse in the SAR imaging process due to the presum) is generated. The clutter suppression processor 19 reduces the reflected signal from the fixed target from the signal after the compression, and outputs only the signal of the moving target. The output signal is subjected to Doppler frequency analysis in the frequency analyzer 20 and amplitude detection is performed by the detector 14. After the amplitude detection, the target is detected by the target detector 21 using the Σ signal. The angle detector 22 calculates an error voltage from the ratio of the Σ signal and the Δ signal in the detected target range bin (FIG. 2).
(B)) The target angle from the boresight direction of the antenna is calculated. The target position calculator 23 calculates the position of the target on the SAR image from the detected distance and angle of the moving target.
A symbol is superimposed and displayed at the correct position of the moving target on the R image.

Embodiment 2 FIG. FIG. 3 is a block diagram showing a second embodiment of the present invention.
Is the same as in the first embodiment. Reference numeral 25 denotes a Doppler correction processor, which corrects a change in Doppler frequency caused by movement of a target.

Next, the operation will be described. In the moving target detection processing, the moving range of the target detected by the target detector 21 is calculated using the Doppler frequency of the moving target calculated by the frequency analyzer 20. Note that the target speed is obtained by [Equation 1] using the Doppler frequency f _d and the wavelength λ.

[0020]

(Equation 1)

The average of the movement amount of the target is obtained from the obtained speed of the target and the observation time, and the average is used as a correction amount, and the range movement correction processor 7 corrects the movement of the target range. Further, a change amount of the target Doppler frequency during the observation time is obtained based on the target Doppler frequency obtained by the frequency analyzer 20. This is used as the correction amount, and the Doppler correction processor 25
The correction of the target Doppler frequency change is performed. Through these processes, the target is as if it were stopped (there is no linear motion component). When the target frequency analysis is performed in the frequency analyzer 20 using the data after the correction,
A Doppler frequency generated by a target rotational motion component can be extracted. This is detected in amplitude by the detector 14 to create a target two-dimensional (range-Doppler) image.

Embodiment 3 FIG. FIG. 4 is a block diagram showing a third embodiment of the present invention. In the drawing, 1 to 25 are the same as those of the first and second embodiments. 26 is a coordinate converter,
This is to convert the coordinates in the cross range direction in the ISAR image of the moving target from the Doppler frequency to the distance.

Next, the operation will be described. 1-3,5
The SAR imaging process and the moving target detection process up to 25 are the same as those in the first to third embodiments. Azimuth direction presum processor 1 for Σ and Δ signals output from receiver
7, the sampling frequency is lowered.
To create a narrow pulse. Thereafter, the target range movement is corrected by the ISAR imaging range movement correction processor 7, and the target Doppler frequency change is corrected by the Doppler correction processor 25. A frequency analysis is performed on each of the results of the Σ signal and the Δ signal, and two ISAR images are created. Two error voltages (Δ / Σ) at two points are obtained from the ISAR image, and the angle is calculated. The distance r between the two points can be obtained from [Equation 2] from the angle θ between the two points and the distance R to the target.

[0024]

(Equation 2)

Since the Doppler frequency difference between two points is proportional to the distance, the coordinates in the cross-range direction of the ISAR image are calculated from the Doppler frequency based on the distance obtained between the two points. ) Can be converted. This processing is performed in the coordinate converter 26, and the range
Convert from Doppler to range-range image.

Embodiment 4 FIG. 5 shows a fourth embodiment, in which 27 antennas 1 and 28 antennas 2 instead of the monopulse antenna of the third embodiment are used.
With two antennas. One antenna is used for transmission, and two antennas are used for reception.
Signal 1 of the received signal obtained from these two antennas is represented by S
The signal is output to the AR processing, and the signal 1 and the signal 2 are output to the moving target detection processing and the ISAR processing. The SAR process is the same as in the first to third embodiments. The signals 1 and 2 output to the moving target detection processing are respectively a range direction presum processor 18, a pulse compressor 6, and a clutter suppression processor 1.
9, processed by the frequency analyzer 20 and the detector 14. Thereafter, the target of the signal 1 is detected by the target detector 21. Using the detected phase difference between the signal 1 and the signal 2 in the target, the angle detector 25 calculates the target angle. The principle will be described. As shown in FIG. 6, assuming that the distance between the two antennas is d and the target angle is θ, the phase difference Δφ of the signals received by the two antennas is expressed by the following equation (3) using the difference X in the distance to each antenna. Desired.

[0027]

(Equation 3)

From this, it can be seen that the target angle can be detected if the phase difference between the signal 1 and the signal 2 is obtained. Similarly, range shift correction processor 7, Doppler correction processor 23, and frequency analyzer 19 for signal 1 and signal 2, respectively.
And the processing by the detector 14 to create two ISAR images. From the created ISAR image, two points A and B
(FIG. 8A). Similarly, the phases of A 'and B' are obtained from another ISAR image. (FIG. 8 (b)). The phase differences between AA ′ and BB ′ are represented by [Equation 4] and [Equation 5].

[0029]

(Equation 4)

[0030]

(Equation 5)

As a result, the angles θ _A and θ of the points _A and B are
_B can be obtained by [Equation 6] and [Equation 7].

[0032]

(Equation 6)

[0033]

(Equation 7)

From the angles of A and B and the distance R, the distance r _AB between _AB can be obtained by [Equation 8].

[0035]

(Equation 8)

Since the Doppler frequency difference between a certain two points and the distance between the two points are proportional, the coordinates in the cross range direction of the ISAR image are calculated based on the distance r _AB between the two points obtained earlier. It can convert from Doppler frequency to range. In the coordinate converter 26, this process is performed for some isolated reflection points, and the conversion from the Doppler frequency to the range is performed based on the average value.

Embodiment 5 In order to obtain a long-range, high-resolution image in such an aircraft-mounted radar device, the ambiguity of the distance and the ambiguity of the frequency become problems. In order to observe a target over a long distance, the PRF must be set to the condition shown in [Equation 9].

[0038]

(Equation 9)

Here, R is the target distance and c is the speed of light. Also, when trying to increase the resolution in the azimuth direction,
The condition shown in [Equation 10] is derived from the beam width θ _{az in} the azimuth direction, the own vehicle speed v, and the wavelength λ.

[0040]

(Equation 10)

Here, the coefficient 1.5 is an oversampling for preventing the aliasing of the frequency. The length L of the antenna uses the resolution X _a and the number N of multi-looks,
It is obtained by [Equation 11].

[0042]

[Equation 11]

From these conditions, when the frequency in the X band used for a general airborne radar is used, the range 1
In order to satisfy 60 NM or more, the resolution 3 m, the number of multi-looks 3 to 4 and the own speed 170 to 190 m / s, the sampling frequency in the SAR imaging process is 260 to 380.
Hz, the PRF at the time of transmission is 500 Hz or less, and the antenna length is 1.5 to 2 m. When a moving target of 60 knots or more is detected as a high-speed moving target, the PRF at the time of transmission needs to be 2000 Hz or more (the maximum detection distance at this time is 40 NM).

Embodiment 6 FIG. Since it is difficult to mount the antenna having the size as in the fifth embodiment on the nose of the aircraft, it is necessary to mount the antenna horizontally on the lower or upper part of the aircraft. At that time, an antenna is attached as shown in FIG. 8 in order to avoid radio wave interference with the airframe. Angle from the antenna boresight direction to the edge of the aircraft's body ψ
Is installed so as to be equal to or more than の of the beam width, it is possible to eliminate radio wave interference with the airframe.

[0045]

Since the present invention is configured as described above, it has the following effects.

According to the first aspect of the present invention, by controlling the sampling frequency using azimuth presum processing and limiting the band using range presum processing, the resolution, detection distance performance and signal SAR signal processing and moving target detection processing can be performed without lowering the processing speed.

According to the second aspect, by using the information obtained in the moving target detection processing, the ISAR signal processing can be performed only by adding one processing.

According to the third aspect of the present invention, by using the ク ロ ス signal and the Δ signal obtained from the monopulse antenna, the coordinates of the moving target in the cross range direction in the ISAR image can be converted from the Doppler frequency to the range. .

According to the fourth aspect of the present invention, the angle measurement accuracy of the moving target can be improved by using the phase difference between the signals obtained from the two antennas.
The coordinates in the cross range direction in the R image can be converted from the Doppler frequency to the distance.

According to the fifth aspect of the present invention, the PRF of the transmission pulse is set to 2000 Hz or more, the rate after the presum processing in the azimuth direction is set to 260 to 380 Hz, and the antenna length is set to 1.5 to 2 m. Band radar, own speed 170-190 m / s, multi-look number 3
The performance of the resolution of 3 m can be satisfied by ４4.

According to the sixth aspect of the present invention, the antenna is mounted on the upper part of the body such that the angle に 対 す る from the antenna boresight direction to the edge located at the shortest distance of the own body is equal to or more than 以上 of the beam width. Alternatively, a large antenna can be mounted without being interfered by radio waves with the airframe by being mounted horizontally on the lower part.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a conceptual diagram showing the basic principle of angle measurement using a monopulse.

FIG. 3 is a configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a configuration diagram showing a third embodiment of the present invention.

FIG. 5 is a configuration diagram showing a fourth embodiment of the present invention.

FIG. 6 is a conceptual diagram showing a basic principle of angle measurement using two antennas.

FIG. 7 shows an isolated reflection point A,
It is a conceptual diagram which shows B, A ', and B'.

FIG. 8 is a diagram showing a sixth embodiment of the present invention.

FIG. 9 is a configuration diagram of a conventional airborne radar device.

FIG. 10 is a conceptual diagram showing a shift in Doppler frequency due to movement of a target.

FIG. 11 is a conceptual diagram illustrating a shift of an SAR image due to movement of a target.

[Explanation of symbols]

Reference Signs List 1 exciter, 2 transmitter, 3 transmission / reception switch, 4 antenna, 5 receiver, 6 pulse compressor, 8 inertial reference unit, 9 buffer memory, 10 FFT calculator, 11
Reference function generator, 12 complex multiplier, 13 IFFT operator, 14 detector, 15 multi-look processor, 16
Monopulse antenna, 17 azimuth direction presum processor, 18 range direction presum processor, 19 clutter suppression processor, 20 frequency analyzer, 21 target detector, 22 angle detector, 23 target position calculator, 24
Superposition processor, 25 Doppler correction processor, 26
Coordinate converter, 27 antenna 1, 28 antenna 2, 2
9 own aircraft, 30 fixed targets, 31 moving targets.

Claims (6)

[Claims] An exciter for generating a continuous wave having a constant frequency, a transmitter for generating a frequency-modulated transmission pulse signal at a constant pulse repetition frequency, and radiating the transmission pulse signal toward a target. A monopulse antenna that receives a reflected signal from a target and outputs a Σ signal and a Δ signal of the received signal, a transmission / reception switch that switches between transmission and reception, and a reception that obtains a video signal by amplifying and phase detecting the received signal. , An arithmetic unit that lowers the sampling frequency of the received signal, a pulse compressor that demodulates the frequency modulation in the resampled signal to generate a narrow pulse, and is caused by the movement of the own equipment in the signal after pulse compression. A computing unit that corrects the change in distance to the target, a buffer memory that temporarily stores the data of the received signal, and a buffer that is read from the buffer memory. An arithmetic unit that performs a fast Fourier transform on the received signal, an inertial reference device that senses the movement and motion of the own device, and a reference for performing azimuth compression using the movement and motion data of the own device output from the inertial reference device. A computing unit that creates a function, a computing unit that performs a complex multiplication of the result of the fast Fourier transform and the reference function, a computing unit that performs the inverse fast Fourier transform on the result of the complex multiplication, and a computing unit that performs the inverse fast Fourier transform. A detector that detects the amplitude of a signal to create an image, an arithmetic unit that performs multi-look processing to reduce speckle noise in the image whose amplitude is detected, and an arithmetic operation that limits the band of a signal output from a receiver And a pulse compressor that demodulates the band-limited signal and generates a narrow pulse,
An arithmetic unit that reduces the clutter signal in the signal after pulse compression and extracts only the moving target signal, an arithmetic unit that analyzes the Doppler frequency of the signal after clutter suppression, and detection that detects the amplitude of the signal after frequency analysis Detector, a target detector for detecting a target from the detected signal with a certain false alarm probability, an arithmetic unit for detecting the target angle using the detected target Σ signal and Δ signal, and a calculator based on the detected angle. And a calculator for calculating the position of the moving target in the synthetic aperture radar image, and a calculator for superimposing the symbol of the moving target on the multi-look processed synthetic aperture radar image. . 2. An exciter for generating a continuous wave having a constant frequency, a transmitter for generating a frequency-modulated transmission pulse signal at a constant pulse repetition frequency, and radiating the transmission pulse signal toward a target. A monopulse antenna that receives a reflected signal from a target and outputs a Σ signal and a Δ signal of the received signal, a transmission / reception switch that switches between transmission and reception, and a reception that obtains a video signal by amplifying and phase detecting the received signal. , An arithmetic unit that lowers the sampling frequency of the received signal, a pulse compressor that demodulates the frequency modulation in the resampled signal to generate a narrow pulse, and is caused by the movement of the own equipment in the signal after pulse compression. A computing unit that corrects the change in distance to the target, a buffer memory that temporarily stores the data of the received signal, and a buffer that is read from the buffer memory. An arithmetic unit that performs a fast Fourier transform on the received signal, an inertial reference device that senses the movement and motion of the own device, and a reference for performing azimuth compression using the movement and motion data of the own device output from the inertial reference device. A computing unit that creates a function, a computing unit that performs a complex multiplication of the result of the fast Fourier transform and the reference function, a computing unit that performs the inverse fast Fourier transform on the result of the complex multiplication, and a computing unit that performs the inverse fast Fourier transform. A detector that detects the amplitude of a signal to create an image, an arithmetic unit that performs multi-look processing to reduce speckle noise in the image whose amplitude is detected, and an arithmetic operation that limits the band of a signal output from a receiver And a pulse compressor that demodulates the band-limited signal and generates a narrow pulse,
An arithmetic unit that reduces the clutter signal in the pulse-compressed signal and extracts only the moving target signal, an arithmetic unit that analyzes the Doppler frequency of the clutter-suppressed signal, and a detector that detects the amplitude of the frequency-analyzed signal And a target detector that detects a target from the amplitude detected signal with a constant false alarm probability, a calculator that detects the target angle using the detected target Σ signal and Δ signal, and a detected angle based on the detected angle. An arithmetic unit for calculating the position of the moving target in the synthetic aperture radar image, an arithmetic unit for superimposing the symbol of the moving target on the multi-look processed synthetic aperture radar image, and a target generated by the movement of the target detected by the target detector An arithmetic unit for correcting a change in distance to the target using the frequency analysis result, an arithmetic unit for correcting a change in Doppler frequency caused by movement of the target, A calculator for analyzing the frequency and obtaining a difference in Doppler frequency due to rotation of the target, and a detector for detecting the amplitude of the output signal and creating an inverse synthetic aperture radar image of the moving target, Airborne radar equipment. 3. An exciter for generating a continuous wave of a constant frequency, a transmitter for generating a frequency-modulated transmission pulse signal at a constant pulse repetition frequency, and radiating the transmission pulse signal toward a target. A monopulse antenna that receives a reflected signal from a target and outputs a Σ signal and a Δ signal of a received signal, a transmission / reception switch that switches between transmission and reception, and a receiver that amplifies and phase-detects a received signal to obtain a video signal An arithmetic unit for lowering the sampling frequency of the received signal, a pulse compressor for demodulating the frequency modulation in the resampled signal to generate a narrow pulse, and a target generated by the movement of the own device in the signal after the pulse compression. Computing unit that corrects the change in distance to the buffer, buffer memory that temporarily stores the data of the received signal, and data that is read from the buffer memory. Creates an arithmetic unit that performs fast Fourier transform of the received signal, an inertial reference device that detects the movement and movement of the own device, and a reference function for azimuth compression based on the movement and movement data of the own device output from the inertial reference device Computing unit that performs complex multiplication of the result of the fast Fourier transform with the reference function, a computing unit that performs the inverse fast Fourier transform on the result of the complex multiplication, and the amplitude of the inverse fast Fourier transformed signal A detector that creates an image by performing detection, an arithmetic unit that performs multi-look processing to reduce speckle noise of an image whose amplitude is detected, and an arithmetic unit that limits the band of a signal output from a receiver, A pulse compressor that demodulates the band-limited signal to generate a narrow pulse, a calculator that reduces the clutter signal in the pulse-compressed signal and extracts only the moving target signal, and a clutter An arithmetic unit for analyzing the Doppler frequency of the suppressed signal, a detector for detecting the amplitude of the frequency-analyzed signal, a target detector for detecting a target from the amplitude-detected signal with a constant false alarm probability, and a target An arithmetic unit for detecting the target angle using the Σ signal and the Δ signal, an arithmetic unit for calculating the position of the moving target in the synthetic aperture radar image based on the detected angle, and a multi-look processed synthetic aperture radar image , A computing unit that superimposes a symbol of a moving target, a computing unit that corrects a change in distance to the target caused by the movement of the detected target using a frequency analysis result, and a change in Doppler frequency caused by movement of the target. Calculator for analyzing the target frequency and obtaining the difference in Doppler frequency due to the rotation of the target, and a moving target for detecting the amplitude of the output signal. A detector that creates an inverse synthetic aperture radar image of the above, an angle detector that detects the angle of each point of the inverse synthetic aperture radar image with a monopulse, and an inverse synthetic aperture radar image based on the obtained angle of each point A coordinate converter for converting coordinates in a cross-range direction from a Doppler frequency to a distance. 4. An exciter for generating a continuous wave having a constant frequency, a transmitter for generating a frequency-modulated transmission pulse signal at a constant pulse repetition frequency, and radiating the transmission pulse signal toward a target. Two antennas for receiving a reflected signal from a target, a transmission / reception switch for switching between transmission and reception, a receiver for amplifying and phase detecting a received signal to obtain a video signal, and lowering a sampling frequency of the received signal. An arithmetic unit, a pulse compressor that demodulates frequency modulation of the resampled signal to generate a narrow pulse, and an arithmetic unit that corrects a change in distance to a target caused by movement of the own device in the signal after pulse compression. And a buffer memory for temporarily storing received signal data, and performing a fast Fourier transform on the received signal read from the buffer memory. An arithmetic unit, an inertial reference device for sensing the movement and shaking of the own machine, an arithmetic unit for creating a reference function for azimuth compression based on the movement and shaking data of the own machine output from the inertial reference device, and a fast Fourier A computing unit that performs complex multiplication of the converted result and the reference function, a computing unit that performs inverse fast Fourier transform on the complex multiplied result, and an image is created by detecting the amplitude of the inverse fast Fourier transformed signal A detector, an arithmetic unit that performs multi-look processing to reduce speckle noise in the image whose amplitude is detected, an arithmetic unit that limits the band of the signal output from the receiver, and demodulates the band-limited signal A pulse compressor that generates a narrow pulse, an arithmetic unit that reduces the clutter signal in the signal after the pulse compression and extracts only the moving target signal, and a Doppler frequency of the clutter-suppressed signal An arithmetic unit that analyzes the signal, a detector that detects the amplitude of the signal after the frequency analysis, a target detector that detects a target from the detected amplitude signal with a certain probability of false alarm, and a target using two detected signals. An arithmetic unit for detecting the angle, an arithmetic unit for calculating the position of the moving target in the synthetic aperture radar image based on the detected angle, and an operation for superimposing the symbol of the moving target on the multi-look processed synthetic aperture radar image An arithmetic unit for correcting a change in distance to the target caused by the movement of the detected target using the frequency analysis result, an arithmetic unit for correcting a change in Doppler frequency caused by the movement of the target, and a target frequency And an arithmetic unit for obtaining the difference in Doppler frequency due to the rotation of the target and detecting the amplitude of the output signal to create an inverse synthetic aperture radar image of the moving target. Detector, an angle detector that detects the angle of each point of the inverse synthetic aperture radar image by the phase difference between the inverse synthetic aperture radar images obtained from the two antennas, and inverse synthesis based on the obtained angle of each point A coordinate converter for converting coordinates in a cross-range direction represented by a Doppler frequency of an aperture radar image into a distance; 5. A pulse repetition frequency of a transmission signal for detecting a moving target is set to 2000 Hz or more, and a sampling frequency in a synthetic aperture radar imaging signal processing is set to 260 to 38.
The airborne radar device according to any one of claims 1 to 4, wherein the frequency is in the X band using an antenna having a length of 1.5 m to 2 m at 0 Hz. 6. An antenna mounted horizontally on a lower or upper part of an aircraft, such that an angle from an antenna boresight direction to an edge located at a shortest distance of an airframe of the own aircraft is equal to or more than の of a beam width. An aircraft-mounted radar device according to claim 1.