JPH0829528A - Radar - Google Patents

Abstract

PURPOSE:To simplify the constitution of signal processing section by performing the phase compensation for compensating the Dappler frequency shift caused by the speed of host plane at the phase compensating section in a Doppler tracking section. CONSTITUTION:At first, in a host plane speed component compensating section 8b, a range walk compensating section 81 compensates for the position of a receiving signal from a target for a radar video during a synthetic aperture time based on the speed signal of a host plane received from a navigator. The Doppler frequency shift is then corrected at a Doppler tracking section 13b. In this regard, a phase compensating section 133b determines a phase amount by integrating the Doppler frequency for every transmission frequency calculated at a smoothing section 132 while at the same time determines a phase amount from the moving amount of the host plane based on a speed signal from a plane navigator. These phase amounts are multiplied by the receiving signal in order to compensate for the phase at every transmission timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device mounted on a moving body such as an aircraft.

[0002]

2. Description of the Related Art As a conventional radar device of this type, a high resolution radar ISAR (Inversed Synthetic Apertur) is used.
e Radar: Inverse synthetic aperture radar). For convenience of description of the operation of the ISAR, the ground-installed ISAR will be described first, and then the aircraft-mounted ISAR will be described.

FIG. 12 is a basic configuration diagram of an ISAR for ground installation. In FIG. 12, 1 is a transmitter, 2 is an output of the transmitter 1 to an antenna 3 and a reception signal from the antenna 3 is a receiver 4. Is a signal processor that performs high resolution processing (ISAR processing) based on the output of the receiver 4, and 6 is a display that displays a target high resolution image based on the output of the signal processor 5a.

Further, FIG. 13 shows the signal processor 5a of FIG.
Details of the configuration of the ISAR processing unit 9a that performs the ISAR processing in the inside will be described. In the figure, 12 is a distance tracking unit that corrects the deviation of the position (range cell) of the reception echo that occurs when the target moves, 13 is a Doppler tracking unit that corrects the deviation of the target Doppler frequency, and 14 is an FFT for each range cell.
A Fourier transform unit for performing a Fourier transform by the above to convert into a luminance signal, and a detector unit 15 for detecting the Fourier-transformed signal and outputting it as an image signal.

Next, the operation will be described. The high frequency signal (RF signal) output from the transmitter 1 is circulator 2
Is radiated from the antenna 3 to the free space via. Then, the emitted signal is reflected by a target (not shown). The reflected echo received by the antenna 3 is input to the receiver 4 via the circulator 2. The reflected echo is pulse-compressed in the receiver 4 in order to increase the resolution in the range direction (distance direction from the antenna 3), and then A / D converted into a digital radar video. The radar video is quantized and stored in range cells divided according to the distance from the radar.

On the other hand, ISAR achieves high resolution in the cross range direction (direction orthogonal to the range direction) by performing synthesis on the aperture plane. A target image signal can be obtained by increasing the resolution in the cross range direction by the ISAR processing and by increasing the resolution in the range direction by the pulse compression described above. Transmission and reception in ISAR lasts for a few seconds. This duration is called the synthetic opening time. The signal processor 5a performs ISAR processing on the radar video during this synthetic aperture time to synthesize the aperture plane. The processed signal is output from the signal processor 5a to the display 6 as a detection signal. In this way, the radar image with high resolution in the range direction and the cross range direction is displayed on the display 6.

Next, the ISAR processing section 9 of the signal processor 5a
Details of the operation a will be described with reference to FIG.
The ISAR processing is to generate a two-dimensional (range and Doppler) image by extracting the Doppler frequency component of the reflection echo generated by the rotation of the target. The target typically has both translational and rotational motions, with a Doppler component for each. But ISAR
The target information required for the target is the Doppler component of the rotational motion of the target, and the Doppler component of the translational motion is unnecessary. Therefore, in order to suppress the Doppler component of translational motion,
The distance tracking unit 12 and the Doppler tracking unit 13 perform processing for correcting the deviation of the Doppler frequency while keeping the distance between the antenna 3 and a target (not shown) constant during the synthetic aperture time.

The Fourier transform unit 14 includes a Doppler tracking unit 1
Fast Fourier transform (FFT) is performed on the output of 3,
A Doppler component due to a target rotation (not shown) is extracted.
The detection unit 15 detects the output of the Fourier transform unit 14 and outputs F
The amplitude of the radar video after FT is calculated and output to the display 15 as a detection signal.

The above is a description of the structure and operation of the ground-installed ISAR. Next, the aircraft-mounted ISAR will be described.

FIG. 14 is a basic configuration diagram of an aircraft-mounted ISAR. The ground installation ISAR shown in FIG.
An aircraft navigation device 7 that outputs a velocity signal of an aircraft equipped with an AR is provided, and a velocity component compensation process of a vehicle itself that compensates a range cell shift and a Doppler frequency shift based on the velocity signal in the signal processor 5b. The difference is that the portion 8a is incorporated.

Further, as shown in FIG. 15, the ISAR processing section 9b, unlike the ISAR processing section 9a, internally has its own vibration component compensating section 16 for eliminating the influence of the motion of the aircraft. FIG. 15 is a block diagram showing details of the signal processor 5b. In the figure, reference numeral 8a denotes an own velocity component compensation processing unit for compensating the shift of the range cell and the shift of the Doppler frequency based on the speed signal, and a range walk compensating unit for compensating the target movement (range walk) based on the speed signal. 81 and a phase compensator 82 for correcting the deviation of the target Doppler frequency based on the velocity signal.
Reference numeral 9b denotes an ISAR processing unit, which is a distance tracking unit 12a that corrects a deviation of the position (range cell) of the reception echo that occurs when the target moves, a Doppler tracking unit 13a that corrects a deviation of the target Doppler frequency, and an aircraft Self-vibration component compensating unit 16 for removing the influence of motion, Fourier transform unit 14 for performing Fourier transform by FFT for each range cell, and transforming into a luminance signal, and detection for detecting the Fourier transformed signal and outputting it as an image signal It consists of a part 15.

Further, as shown in FIG. 15, the distance tracking unit 1
Reference numeral 2 denotes a reference point detection unit 121 that detects an isolated reflection point from the target echo, a smoothing unit 122 that smoothes the target Doppler frequency to obtain a Doppler frequency for each transmission pulse, and a range walk that compensates for the target range walk. Compensation unit 123a. In addition, the Doppler tracking unit 13 focuses on a specific range bin of the received signal to calculate a Doppler frequency of the target translational speed, and a smoothing unit that smooths the target Doppler frequency to obtain the Doppler frequency of each transmission pulse. 132 and a phase compensating unit 133a that integrates the smoothed Doppler frequency of each transmission pulse to obtain a phase amount and corrects the phase amount. In addition, the own vibration component compensator 16
Is composed of a phase amount calculation unit 161 for calculating the phase amount of the vibration component and a phase compensation unit 162 for performing phase compensation based on the phase compensation amount calculated by the phase amount calculation unit 161.

Next, the operation of the conventional airborne ISAR will be described. The basic operation as a radar until the transmitter 1 shown in FIG. 14 radiates an RF signal from the antenna 3 and receives a reflected echo (RF signal) from a target (not shown) by the receiver 4 is the same as in the case of ground-based ISAR. It is the same. However, the airborne ISAR differs in that it compensates for its own motion during the synthetic opening time in order to compensate for the effects of the motion of the onboard aircraft itself. The movement of the player's body is roughly divided into a velocity component and an acceleration component. The velocity component can be usually measured by the navigation device 7 mounted on the aircraft, but the acceleration component cannot be measured by the current navigation device. Since the position of the target reception signal and the Doppler frequency are displaced by the movement of the vehicle itself, it is necessary to compensate for each.

Therefore, in the on-board ISAR, for the radar video during the synthetic aperture time, based on the velocity signal of the own device from the navigation device 7, the own velocity component compensation processing unit 8a.
The range walk compensator 81 compensates the position of the target reception signal, and the phase compensator 82 similarly compensates the Doppler frequency by the relative velocity component. Conventionally, the own speed component compensator 8a is configured by hardware.

The radar video from which the influence of the velocity due to the motion of the own device is removed by the own velocity component compensation processing unit 8a is then subjected to ISAR processing in the ISAR processing unit 9b. That is, as in the case of the ground-installed ISAR, the distance tracking unit 12a performs compensation processing in the range direction to maintain the distance between the radar and the target. This process will be described in detail. First, the reference point detection unit 121 pays attention to the amplitude information of the radar video, detects the target position for each transmission pulse during the synthetic aperture time, and calculates the target distance. Smoothing 12
In 2, the target distance in the synthetic aperture time calculated by the reference point detection unit 121 is smoothed, and the target movement amount is calculated based on the synthetic aperture start time. Range walk compensation unit 1
In 23a, the same process as that of the range walk compensating unit 81 is performed based on the movement amount calculated by the smoothing unit 122.

The Doppler tracking unit 13a corrects the deviation of the Doppler frequency. This process will be described in detail. First, the frequency analysis unit 131 focuses on a specific range cell of the received signal and calculates the Doppler frequency of the target translational speed for each transmission pulse. The smoothing unit 132 smoothes the translational Doppler frequency during the synthetic aperture time calculated by the frequency analysis unit 131. Phase compensation analysis unit 133a
Then, the phase amount is obtained by integrating the Doppler frequency for each transmission pulse calculated by the smoothing unit 132, and the received signal is multiplied to perform the same processing as the phase compensating unit 82.

The own-vibration component compensator 16 compensates in the Doppler direction similarly to the Doppler tracking unit 13a. Compensation is performed by extracting and compensating for vibration characteristics from video information. This process will be described in detail. First, in the phase amount calculation unit 161,
Focusing on the change in the phase amount of the radar video, the phase amount of the vibration component is calculated. In the phase compensator 162, the phase amount calculator 1
By multiplying the received signal by the phase compensation amount calculated in 61, the same processing as the phase compensating unit 133a is performed.

[0018]

The conventional radar device is constructed as described above, and the own velocity component compensation processing unit 8 is provided.
The range walk compensation and the phase compensation are duplicated in both a and the ISAR processor 9b.

The present invention has been made to solve the above problems, and an object thereof is to obtain a radar apparatus capable of simplifying the configuration of a signal processing section by avoiding the duplication of processing.

[0020]

A radar apparatus according to a first aspect of the present invention includes a signal processor for performing synthetic aperture processing on a target reflected video signal to generate a high resolution radar image signal,
The synthetic aperture processing is performed by simultaneously compensating for the fluctuation of the video signal due to the movement of the target and the fluctuation of the video signal due to the movement of the moving body on which the radar is mounted.

According to a second aspect of the present invention, in the radar device, the signal processor is used to change the position of the reflected signal of the target in the video signal due to the movement of the target and the video signal due to the movement of the moving body. In this configuration, the synthetic aperture processing is performed after simultaneously compensating for the variation in the position of the target reflection signal therein.

According to a third aspect of the present invention, there is provided a radar apparatus in which the signal processor is provided with a reference point detecting section for detecting a reference point in the target from the video signal, and a frequency of the reference point is detected a plurality of times from a plurality of transmission signals. A smoothing unit that determines the target frequency from the plurality of frequencies to determine the speed and a speed that is obtained by the smoothing unit and the speed of the moving body that is externally given are combined to obtain the speed. It comprises a range walk compensator for finding the relative change in the distance to the target and compensating the position of the target reflected signal in the video signal for each range cell corresponding to the resolution in the distance direction.

According to a fourth aspect of the present invention, in the radar device, the signal processor is used to change the Doppler frequency of the reflected signal of the target in the video signal caused by the movement of the target and the video signal caused by the movement of the moving body. In the above, the synthetic aperture processing is performed after simultaneously compensating for the fluctuation of the Doppler frequency of the target reflected signal.

According to a fifth aspect of the present invention, in the radar device, the signal processor includes a frequency analysis section for detecting the target frequency from the video signal and a plurality of frequency analysis sections output by the frequency analysis section for a plurality of transmission signals. A smoothing unit that determines the target frequency from the frequency to obtain the speed, a target speed obtained by the smoothing unit, and the speed of the moving body given from the outside are synthesized, and the video is based on the synthesis result. And a phase compensator for compensating for the displacement of the Doppler frequency of the target reflected signal in the signal.

According to a sixth aspect of the present invention, there is provided a radar apparatus in which the signal processor is provided with a plurality of frequency analysis sections for detecting the target frequency from the video signal and a plurality of output sections of the frequency analysis section for a plurality of transmission signals. The smoothing unit that determines the target frequency from the frequency to determine the speed, the phase amount calculation unit that determines the distance change to the target due to the vibration of the moving body and outputs the speed, and the smoothing unit A phase compensator for synthesizing the target velocity and the velocity calculated by the phase amount calculator, and compensating the displacement of the Doppler frequency of the target reflection signal in the video signal based on the synthesized result. Is.

[0026]

According to the present invention, the signal processor performs the synthetic aperture processing by simultaneously compensating the fluctuation of the video signal due to the movement of the target and the fluctuation of the video signal due to the movement of the moving body. .

According to a second aspect of the present invention, the signal processor is arranged to change the position of the reflection signal of the target in the video signal due to the movement of the target and the video signal due to the movement of the moving body in the video signal. Synthetic aperture processing is performed after simultaneously compensating for the variation in the position of the target reflected signal.

In the invention of claim 3, the reference point detecting section of the signal processor detects the reference point in the target from the video signal, and the smoothing section detects the frequency of the reference point from the plurality of transmission signals a plurality of times. At the same time as obtaining, the target frequency is specified from these plural frequencies to obtain the speed, and the range walk compensating unit synthesizes the target speed obtained by the smoothing unit and the speed of the moving body given from the outside. The relative distance change to the target is obtained, and the position of the target reflected signal in the video signal is compensated for each range cell corresponding to the resolution in the distance direction.

According to a fourth aspect of the present invention, the signal processor is arranged to change the Doppler frequency of the reflected signal of the target in the video signal due to the movement of the target and the video signal due to the movement of the moving body. The synthetic aperture processing is performed after simultaneously compensating for the fluctuation of the Doppler frequency of the target reflected signal in (1).

According to a fifth aspect of the present invention, the frequency analysis unit of the signal processor detects the target frequency from the video signal, and the smoothing unit outputs a plurality of signals output from the frequency analysis unit to a plurality of transmission signals. The speed is obtained by specifying the target frequency from the frequency of, and the phase compensating unit synthesizes the target velocity obtained by the smoothing unit and the velocity of the moving body given from the outside, and based on the synthesis result. Compensating for Doppler frequency displacement of the target reflected signal in the video signal.

According to a sixth aspect of the present invention, the frequency analysis unit of the signal processor detects the target frequency from the video signal, and the smoothing unit outputs a plurality of signals output from the frequency analysis unit to a plurality of transmission signals. The frequency is calculated by determining the target frequency from the frequency, and the phase amount calculation unit calculates the distance change to the target due to the vibration of the moving body and outputs it as the speed, and the phase compensation unit calculates it by the smoothing unit. The target speed and the speed calculated by the phase amount calculation unit are combined, and the displacement of the Doppler frequency of the target reflected signal in the video signal is compensated based on the combined result.

[0032]

【Example】

Example 1. Hereinafter, the radar device according to the present invention (ISA
An embodiment of R) will be described with reference to FIG. FIG. 1 is a block diagram showing details of the signal processor 5 of the radar device according to the first embodiment. Other transmitters 1, circulators 2 and the like have the same configuration, and therefore their illustration and description are omitted. In the figure, reference numeral 8b is a speed component compensation processing unit for compensating a range cell shift based on a speed signal,
It comprises a range walk compensator 81 for compensating for a target movement (range walk) based on the velocity signal. Reference numeral 9c denotes an ISAR processing unit, which is a distance tracking unit 12a that corrects a deviation of the position (range cell) of the reception echo that occurs when the target moves, a Doppler tracking unit 13b that corrects a deviation of the target Doppler frequency, and an aircraft Self-vibration component compensator 16 for eliminating the influence of motion, F for each range cell
It is composed of a Fourier transform unit 14 which performs Fourier transform by FT and transforms it into a luminance signal, and a detector unit 15 which detects the Fourier transformed signal and outputs it as an image signal.

Further, as shown in FIG. 1, the distance tracking unit 12
a is a reference point detection unit 121 that detects an isolated reflection point from the target echo, a smoothing unit 122 that smoothes the target Doppler frequency to obtain a Doppler frequency for each transmission pulse, and a range walk that compensates the target range walk. Compensation unit 123a. In addition, the Doppler tracking unit 13b is a frequency analysis unit 131 that calculates the Doppler frequency of the target translational speed by focusing on a specific range bin of the received signal, a smoothing unit that smooths the target Doppler frequency and obtains the Doppler frequency for each transmission pulse. 132 and the phase compensating unit 13 that integrates the Doppler frequency for each smoothed transmission pulse to obtain and correct the phase amount, and also corrects the deviation of the Doppler frequency due to the speed of the aircraft based on the speed signal from the airframe navigation device 7.
3b and. Further, the own-machine vibration component compensating unit 16 calculates the phase shift for each hit based on the phase shift calculated by the phase amount calculation unit 161 and the phase amount calculation unit 161 for obtaining the target phase shift for each hit due to the vibration of the own device. And a phase compensator 162 for compensating for In the figure, the phase compensating unit 82 of the velocity component compensating process 8a of the conventional radar device is integrated with the phase compensating unit 133b of the Doppler tracking unit 13 of the ISAR processing unit 9b.

Next, the operation will be described. The basic principle of ISAR is a radar that utilizes the Doppler effect generated by the relative motion of the radar and the target, and the information necessary for signal processing is the Doppler component of the target rotational motion. Therefore, the Doppler component due to the motion of the ship itself and the Doppler component due to the translational motion of the target are unnecessary, and these must be compensated. Since these components can be treated as one motion component as a relative motion between the radar and the target, in the first embodiment, the Doppler tracking unit 13 collectively performs compensation for these components.

The transmitter 1 radiates an RF signal from the antenna 3, and the receiver 4 receives a reflection echo (RF signal) from a target (not shown). Airborne ISARs compensate for the effects of movement of the onboard aircraft itself. The movement of the player's body is roughly divided into a velocity component and an acceleration component. The velocity component can be usually measured by the navigation device 7 mounted on the aircraft.

First, in the velocity component compensation processing unit 8b of the aircraft, the range walk compensation of the velocity component compensation processing unit 8 of the aircraft itself is performed on the radar video during the synthetic aperture time based on the velocity signal of the aircraft from the navigation device 7. The unit 81 compensates the position of the target received signal.

Here, range walk compensation will be described. FIG. 2 is a diagram showing a storage position of a reception signal for each transmission pulse in a relative positional relationship when an aircraft equipped with ISAR approaches a target. In the figure, c
Is the light velocity, and t is the transmission pulse width. At this time, the distance resolution is given by ct / 2, and this is the range cell width (range cell unit) which is the processing unit of the reflected echo in the range direction.
Equivalent to.

In the figure, the transmission pulse is generated at a constant repetition period, and the transmission pulse numbers are sequentially associated with 1 to (m-1) n (m and n are positive integers). Further, a range cell is shown for each transmission pulse number, and a smaller range cell number indicates a position closer to the antenna 3.

First, it is assumed that the received signal of the reflected echo from the target is stored in the Lth range cell at the transmission pulse number 1 immediately after the start of the synthetic aperture. ISAR
Since the aircraft equipped with is approaching the target, the distance becomes shorter as the relative positional relationship between the aircraft and the target changes while the transmission is repeated. As shown in the figure, for the first time with the pulse of the transmission pulse number n, the received signal approaches one range cell and moves to the (L-1) th range cell. Similarly, the target received signal approaches the range cell of (L-2) th by 2 range cells in the pulse of the transmission pulse number 2n, moves to the (L-2) th range cell, and (m-1) in the pulse of the transmission pulse number (m-1) n. Move closer to the range cell and move to the (L-m + 1) th position. In this way, the range cell number in which the target reception signal exists changes with each transmission pulse as the relative positional relationship between the own device and the target changes. By the way, since the ISAR processing is performed on a target reception signal for each transmission pulse, it is necessary to track the reception signal as the reception signal moves to extract the signal. Therefore, the range cell is moved in response to the movement of the received signal, and compensation is performed so that the received signal can always be processed.

Specifically, the range walk compensator 81
As shown in FIG. 3, the range walk compensation amount is obtained by calculating the movement amount of the target reception signal range cell for each transmission pulse with reference to the storage position of the reception signal range cell at the transmission pulse number 1. This is done by shifting the position of. For example, in the case of the transmission pulse 1, since the compensation amount is 0, no processing is performed. In the case of the transmission pulse n, the compensation amount is 1 range cell, so 1 is added before the range cell 1.
Insert a space for the range cell. Similarly, in the case of the transmission pulse 2n, two range cells are transmitted, and the transmission pulse (mn)
In the case of n, the (m-1) range cell is inserted.

Here, the movement amount of the range cell is calculated based on the speed signal obtained from the airframe navigation device 7. Since the movement amount of the range cell is quantized by ct / 2, it is difficult to continuously compensate the storage position corresponding to the velocity signal, and it is compensated for each range cell in processing. This simplifies the process.

The radar video from which the influence of the velocity due to the motion of the own device is removed by the own velocity component compensation processing unit 8 is then subjected to ISAR processing in the ISAR processing unit 9c. First, the reference point detection unit 121 pays attention to the vibration information of the radar video, detects the target position for each transmission pulse during the synthetic aperture time, and calculates the target distance. Smoothing 12
In 2, the target distance in the synthetic aperture time calculated by the reference point detection unit 121 is smoothed, and the target movement amount is calculated based on the synthetic aperture start time. Range walk compensation unit 1
In 23a, the same process as that of the range walk compensating unit 81 is performed based on the movement amount calculated by the smoothing unit 122.

Next, the Doppler tracking unit 13b corrects the deviation of the Doppler frequency. This process will be described in detail. First, the frequency analysis unit 131 focuses on a specific range cell of the received signal and calculates the Doppler frequency of the target translational speed for each transmission pulse. For example, radar video (I
/ Q video) is the one shown in FIG. 4 (a),
Each segment a ₁ , a ₂ , a ₃ , ... A _n using the segment FFT
Calculate the frequency for each. Then, they are plotted as shown in FIG. 4B, the frequency fd _n having the maximum amplitude is obtained, and this is set as the target Doppler frequency. here,
The segmented FFT is an FFT performed for the time when the synthetic aperture time is divided into some segments.

The smoothing unit 132 smoothes the translational Doppler frequency during the synthetic aperture time calculated by the frequency analysis unit 131. For example, the sections a ₁ , a ₂ , and a in FIG.
_3, the Doppler frequency of the target determined for each · · · a _n, and a straight line drawn so plotted as in Figure 5, the error is reduced for each Doppler frequency (e.g., regression line), transmission pulse The target Doppler frequency is calculated for each.

The phase compensator 133b obtains the phase amount by integrating the Doppler frequency for each transmission pulse calculated by the smoothing unit 132. At the same time, the phase compensator 1
33b obtains the moving amount ΔR (t) (t: time based on the synthetic opening start time) of the own aircraft from the speed signal from the airframe navigation device 7, and calculates this by the expression exp (j · 4πΔR (t) /
The phase amount is obtained by substituting it into λ) (j: imaginary unit, λ: transmission wavelength). Then, phase compensation is performed by multiplying the received signal by these phase amounts. This compensation is performed for each transmission timing.

The own-machine vibration component compensator 16 is for compensating in the Doppler direction similarly to the Doppler tracking unit 13b. Compensation is performed by extracting and compensating the vibration characteristic from the information.

Explaining this process in detail, first, the phase amount calculator 161 pays attention to the change in the phase amount of the radar video and calculates the phase amount of the vibration component. This is shown in FIG.
Will be explained. If there is no vibration of the machine,
As shown in (a), the phase of the isolated reflection point of the target changes linearly with respect to time based on the relative motion between the target and the player's aircraft (straight line p in the figure). However, when the own machine vibrates, the phase of the isolated reflection point fluctuates irregularly as a ₁ , a ₂ , ..., A ₆ for each hit of the transmission pulse as shown in FIG. 6B. To do. Therefore, in order to compensate the vibration of the own device, it is sufficient to perform compensation so that all the observed phases are on the straight line p as shown in FIG. The phase compensation amounts b ₁ , b ₂ , ..., B _{6 at} this time are obtained as follows. Since the Doppler tracking unit 13b knows the Doppler frequency based on the relative motion between the target and the player's aircraft, the straight line p in FIG. 6 can be known from this. Therefore, the phases a ₁ , a ₂ , ... Of the isolated reflection points observed with reference to the straight line p
.., a ₆ to the straight line p, the phase compensation amounts b ₁ , b ₂ , ..., B ₆ can be obtained.

In the phase compensator 162, the phase amount calculator 161
Phase compensation amount b _1, b ₂ calculated in, performing phase compensation on the basis of the · · · b _6. The specific method of phase compensation is the same as the case of the phase compensation unit 133b of the Doppler tracking unit 13b.

The Fourier transform unit 14 performs a fast Fourier transform (FFT) on the output of the self-vibration component compensation unit 16 to extract a Doppler component due to a target rotation (not shown). The detection unit 15 detects the output of the Fourier transform unit 14 to calculate the amplitude of the radar video after FFT, and outputs it to the display unit 15 as a detection signal.

As described above, according to the radar apparatus of the first embodiment, the phase compensation for compensating the deviation of the Doppler frequency due to the speed of the own device is also combined in the phase compensating unit for performing the phase compensation of the Doppler tracking unit. Since only one phase compensation process is required, the configuration is simplified, and the time required for the process can be shortened to enable high-speed processing.

Example 2. In the first embodiment described above, the Doppler tracking unit 13b integrates the Doppler phase compensation of the velocity component of the vehicle and the translational component to the target. On the other hand,
Since the compensation of the vibration component of the own device is also the phase compensation in the Doppler direction, the Doppler tracking 13b and the vibration component compensation 14 of the own device may be integrated and processed in the same block.

FIG. 7 shows a functional block diagram of signal processing of the radar system of the second embodiment. In the figure, 17a is a Doppler compensating unit that performs Doppler tracking processing and own-machine vibration component compensation processing. The Doppler compensating unit focuses on a specific range bin of the received signal to calculate a Doppler frequency of the target translational speed, a smoothing unit 172 that smooths the target Doppler frequency to obtain the Doppler frequency of each transmission pulse, Based on the phase amount calculation unit 173 for obtaining a target phase shift for each hit due to the vibration of the machine and the phase amount and the phase shift calculated by the phase amount calculation unit 173 by integrating the Doppler frequency for each smoothed transmission pulse. And a phase compensator 174a that corrects the deviation of the Doppler frequency.

The own speed component compensation processing unit 8a is shown in FIG.
5, the distance tracking unit 12a, the Fourier transform unit 14, and the detection unit 15 are the same as those shown in FIG.

Next, the operation will be described. The difference from the operation of the radar device of FIG. 1 is the operation of the Doppler compensating unit 17a, so this part will be described. In the second embodiment, the Doppler tracking 13a shown in FIG.
Are collectively processed by the Doppler compensation unit 17a.

Explaining this processing in detail, first, the frequency analysis unit 171 pays attention to a specific range cell of the received signal and calculates the Doppler frequency of the target translational speed for each transmission pulse. The smoothing unit 172 smoothes the translational Doppler frequency during the synthetic aperture time calculated by the frequency analysis unit 171.

The phase amount calculation unit 173 calculates a phase amount that provides a constant phase amount regardless of the target translational velocity. For example, as shown in FIG. 8, when the phase of the signal observed for each transmission pulse is a ₁ , a ₂ , ..., A ₆ , the phase amount is such that each phase becomes “0”. Find b ₁ , b ₂ , ... b ₆ . Specifically:
a _1, -a _2, ···, a -a _6.

The phase compensator 174a multiplies the received signal by the phase amount calculated by integrating the Doppler frequency for each transmission pulse calculated by the smoothing unit 133 and the phase amount calculated by the phase amount calculator 173. I do. This compensation is performed for each transmission timing. The specific processing is the same as in the case of the phase compensation unit 133b in FIG.

In the above description, the phase amount calculation unit 173 is used.
Although the case where "phase = 0" is described as an example of the reference phase in Fig. 5, the reference phase is merely a reference value and may be "phase = π" or "phase = -π" without being limited to "0". .

As described above, according to the radar apparatus of the second embodiment, the phase compensation for compensating the deviation of the Doppler frequency due to the vibration of the own machine is also performed by the phase compensating unit for performing the phase compensation of the Doppler tracking unit. Since the processing is performed, only one phase compensation process is required, the configuration is simplified, and the time required for the process can be shortened to enable high-speed processing. Further, since the phase amount is calculated by a simple method, the calculation in the phase amount calculation means becomes simple and the processing time becomes shorter.

Example 3. Combining the first embodiment and the second embodiment, the Doppler compensating unit 17b of the ISAR processing unit 9d compensates the phase of the velocity component of the own vehicle, compensates for the deviation of the Doppler frequency due to the relative motion between the target and the own vehicle, and The phase compensation of the vibration component may be performed simultaneously. FIG. 9 shows a functional block diagram of the signal processor of the radar apparatus according to the third embodiment.

In FIG. 9, reference numeral 17b denotes a Doppler compensating section for carrying out own-machine velocity component compensation processing, Doppler tracking processing and own-machine vibration component compensation processing. The phase compensating unit 174b of the Doppler compensating unit 17b is different from the above-described first and second embodiments in that the phase compensating unit 174b performs the phase compensating for these three processes, but since the contents of each process are the same, the description thereof will be omitted. To do.

As described above, according to the radar apparatus of the third embodiment, the phase compensation for compensating for the deviation of the Doppler frequency due to the velocity component of the vehicle itself and the deviation of the Doppler frequency due to the vibration of the vehicle itself is performed by the Doppler tracking unit. Since the phase compensation unit that performs the phase compensation is also performed, only one phase compensation process is required, the configuration is simpler, and the time required for the process can be shortened to enable higher speed processing. Further, since the phase amount is calculated by a simple method, the calculation in the phase amount calculation means becomes simple and the processing time becomes shorter.

Example 4. In the first to third embodiments, the compensation function for Doppler is integrated, but instead of or in addition to these, the distance direction (range direction)
It is also possible to integrate the compensation function for.

FIG. 10 shows a functional block diagram of the signal processor of the radar apparatus according to the fourth embodiment. Reference numeral 12b is a distance tracking unit that compensates for both the range walk caused by the velocity component of the own vehicle and the range walk caused by the relative movement between the target and the own vehicle. The range walk compensating unit 123b of the distance tracking unit 12b compensates for the velocity component of the own vehicle based on the velocity signal from the navigation device 7, and also performs the compensation based on the target and the relative velocity of the own aircraft obtained by the smoothing unit 122. Specifically, the range walk compensation may be performed with a new compensation amount obtained by adding the compensation amount resulting from the relative speed between the target and the own device to the compensation amount described with reference to FIG. 3 in the first embodiment.

Alternatively, range walk compensation may be performed based on the amplitude information of the radar video obtained by the smoothing unit 122 instead of the velocity signal from the airframe navigation device 7. In this case, the speed signal from the outside is unnecessary.

As described above, according to the radar apparatus of the fourth embodiment, the range tracking unit also performs the range walk compensation by the speed of the own machine, so that only one range walk process is required. The configuration is simplified, the processing time can be shortened, and high-speed processing becomes possible. Further, as a result, an external interface between the respective components is not required, which further simplifies the configuration.

Example 5. The above-described first to fourth embodiments may be put together to integrate and integrate the compensation functions in both the Doppler direction and the range direction to the necessary minimum. FIG. 11 shows a functional block diagram of the signal processor of the radar device of the fifth embodiment.

The radar apparatus according to the fifth embodiment has a simpler configuration than any of the radar apparatuses according to the first to fourth embodiments, and the processing time can be shortened to enable high-speed processing.

[0069]

As described above, according to the first aspect of the invention, the signal processor of the radar device mounted on the moving body is provided with the video signal fluctuation due to the movement of the target and the video signal due to the movement of the moving body. Since the synthetic aperture processing is performed by simultaneously compensating for the fluctuations of the above, the compensation processing for the fluctuations does not overlap, and the structure is simple and high-speed processing is possible.

According to a second aspect of the present invention, the signal processor is arranged to change the position of the reflection signal of the target in the video signal due to the movement of the target and the video according to the movement of the moving body. Since the synthetic aperture processing is performed after simultaneously compensating for the positional fluctuation of the target reflected signal in the signal, the compensating processing for the positional fluctuation does not overlap, and the configuration is simple and high-speed processing is possible. Will be possible.

According to a third aspect of the present invention, the signal processor includes a reference point detecting section for detecting a reference point in the target from the video signal, and a frequency of the reference point from a plurality of transmission signals. A plurality of times is obtained, and a smoothing unit that obtains a speed by specifying the target frequency from the plurality of frequencies, a target speed obtained by the smoothing unit, and a predetermined speed of the moving body are combined. Since the change of the relative distance to the target is obtained and the range walk compensating unit for compensating the position of the target reflected signal in the video signal for each range cell corresponding to the resolution in the distance direction, There is no need for a dedicated range walk compensator for compensating for changes in the above target distance due to body movements, and the configuration is simple and high-speed processing is possible. Range Walk compensation is facilitated because the process every.

According to a fourth aspect of the present invention, the signal processor is configured to change the Doppler frequency of the target reflected signal in the video signal due to the target movement and the movement of the moving body. Since the synthetic aperture processing is performed after simultaneously compensating for the fluctuation of the Doppler frequency of the target reflected signal in the video signal, the composition is simplified without compensating processing for the fluctuation of the Doppler frequency. High-speed processing becomes possible.

Further, according to the invention of claim 5, the signal processor outputs the frequency analysis section for detecting the target frequency from the video signal and the frequency analysis section for a plurality of transmission signals. A smoothing unit that determines the speed by specifying the target frequency from a plurality of frequencies, synthesizes the target velocity obtained by the smoothing unit and the velocity of the moving body given in advance, and based on the result of the synthesis, Since it is composed of a phase compensator that compensates for the displacement of the Doppler frequency of the target reflected signal in the video signal, a dedicated phase compensator for compensating for the fluctuation of the Doppler frequency due to the motion of the moving body is not required. The configuration is simple and high-speed processing is possible.

According to the invention of claim 6, the signal processor outputs the frequency analysis section for detecting the target frequency from the video signal and the frequency analysis section for a plurality of transmission signals. The smoothing unit that determines the speed by specifying the target frequency from a plurality of frequencies, the phase amount calculation unit that calculates the distance change to the target due to the vibration of the moving body and outputs the speed, and the smoothing unit. And a phase compensating unit for compensating the displacement of the Doppler frequency of the target reflection signal in the video signal based on the result of the synthesis, by synthesizing the target velocity and the velocity calculated by the phase amount calculating unit. Therefore, the compensating process for the fluctuation of the Doppler frequency does not overlap, the configuration is simple, and the high-speed process is possible. Further, the structure is further simplified by not requiring a speed signal from the outside.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a signal processor of a radar device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an operation of a range walk compensation processing unit according to the first embodiment.

FIG. 3 is an explanatory diagram of an operation of a range walk compensation processing unit according to the first embodiment.

FIG. 4 is an explanatory diagram of an operation of the frequency analysis unit according to the first embodiment.

FIG. 5 is an explanatory diagram of the operation of the smoothing unit according to the first embodiment.

FIG. 6 is an explanatory diagram of an operation of the phase amount calculation unit according to the first embodiment.

FIG. 7 is a functional block diagram of a signal processor of a radar device according to a second embodiment of the present invention.

FIG. 8 is an explanatory diagram of an operation of a phase amount calculation unit according to the second embodiment.

FIG. 9 is a functional block diagram of a signal processor of a radar device according to a third embodiment of the present invention.

FIG. 10 is a functional block diagram of a signal processor of a radar device according to a fourth embodiment of the present invention.

FIG. 11 is a functional block diagram of a signal processor of a radar device according to a fifth embodiment of the present invention.

FIG. 12 is a configuration diagram of a conventional ground-based radar device.

FIG. 13 is a functional block diagram of a signal processor of a conventional ground-based radar device.

FIG. 14 is a configuration diagram of a conventional radar device mounted on an aircraft.

FIG. 15 is a functional block diagram of a signal processor of a conventional radar device mounted on an aircraft.

[Explanation of symbols]

8 own speed component compensation processing unit, 9 ISAR processing unit, 1
2 distance tracking unit, 13 Doppler tracking unit, 14 Fourier transform unit, 15 detection unit, 16 own vibration component compensation unit, 1
7 Doppler compensator, 81 Range walk compensator, 8
2 phase compensation section, 121 reference point detection section, 122 smoothing section, 123 range walk compensation section, 131
Frequency analyzing section, 132 smoothing section, 133 phase compensating section, 161 phase amount calculating section, 162 phase compensating section,
171 frequency analysis unit, 172 smoothing unit, 173
Phase amount calculation unit, 174 Phase compensation unit.

Claims (6)

[Claims] 1. A transmitter for generating a transmission signal, an antenna for radiating the transmission signal and receiving a reflected signal from a target, a receiver for receiving and processing the reflected signal to generate a video signal, A radar device mounted on a moving body, comprising: a signal processor that performs a synthetic aperture process on a video signal to generate a high-resolution radar image signal; and a display that displays the high-resolution radar image signal. A radar device, characterized in that the signal processor is configured to perform a synthetic aperture process by simultaneously compensating for the fluctuation of the video signal due to the movement of the target and the fluctuation of the video signal due to the movement of the moving body. 2. The signal processor is configured to change the position of the target reflection signal in the video signal due to the movement of the target and the target reflection signal in the video signal due to the movement of the moving body. 2. The radar apparatus according to claim 1, wherein the synthetic aperture processing is performed after simultaneously compensating for the position variation of the position. 3. The signal processor comprises: a reference point detection unit for detecting a reference point in the target from the video signal; a frequency of the reference point obtained from a plurality of transmission signals a plurality of times; From the smoothing section that determines the target frequency to obtain the speed, and the target speed obtained by the smoothing section and the externally given speed of the moving body are combined to obtain the relative distance to the target. 3. The radar device according to claim 2, further comprising: a range walk compensating unit that obtains a change in the target signal and compensates the position of the target reflected signal in the video signal for each range cell corresponding to the resolution in the distance direction. . 4. The signal processor comprises: a variation of the Doppler frequency of the reflected signal of the target in the video signal due to the movement of the target; and a reflection of the target in the video signal due to the movement of the moving body. 2. The radar apparatus according to claim 1, wherein the synthetic aperture processing is performed after simultaneously compensating for the fluctuation of the signal Doppler frequency. 5. The signal processor includes: a frequency analysis unit that detects the target frequency from the video signal; and a target frequency from a plurality of frequencies output by the frequency analysis unit for a plurality of transmission signals. A smoothing unit that obtains a speed by specifying it, synthesizes the target velocity obtained by the smoothing unit and the velocity of the moving body given from the outside, and reflects the target in the video signal based on the synthesis result. The radar device according to claim 4, wherein the radar device comprises a phase compensating unit for compensating for the displacement of the signal Doppler frequency. 6. The signal processor comprises: a frequency analysis unit for detecting the target frequency from the video signal; and a target frequency from the plurality of frequencies output by the frequency analysis unit for a plurality of transmission signals. A smoothing unit that specifically determines the speed, a phase amount calculation unit that calculates the distance change to the target due to the vibration of the moving body and outputs it as a speed, and the target speed and the phase amount calculated by the smoothing unit. 5. A phase compensating unit for synthesizing the velocity calculated by the calculating unit and compensating the displacement of the Doppler frequency of the target reflection signal in the video signal based on the result of the synthesizing. The described radar device.