KR101742056B1 - Target tracking method for synthetic aperture radar seeker - Google Patents

Abstract

We disclose target tracking method of synthetic aperture radar (SAR) explorer. In the present invention, a fixed frequency waveform pulse according to the DBS technique and a stepped frequency waveform (SFW) pulse for applying the HRR (High Range Resolution) technique for improving the distance resolution are alternately repeatedly emitted in the high resolution mode, By combining the distance data obtained from the distance profile obtained from the distance profile obtained by the HRR method on the obtained high resolution image with improved distance data, a high resolution image with improved distance resolution as well as azimuth resolution can be obtained. Therefore, precise target images can be obtained, so that the target can be accurately detected and tracked.

Description

{TARGET TRACKING METHOD FOR SYNTHETIC APERTURE RADAR SEEKER}

The present invention relates to a target tracking method of a synthetic aperture radar searcher, and more particularly to a target tracking method of a synthetic aperture radar searcher capable of simultaneously operating a Doppler beam sharpening technique and HRR.

The navigator may be configured to track a terrestrial or marine target, depending on the purpose of use. Especially, the navigator for guided weapons is mostly used as an electromagnetic wave searcher, and it is configured to detect a target by emitting and receiving a very high frequency signal within a predetermined angle range based on the moving direction. However, since the beam width is wide, angle resolution is not good. Especially, the navigator for guided vehicles to intercept a target such as a ship in the sea near the coast can not accurately detect the target due to the influence of the ground clutter reflected on the land when the land exists at the same distance within the beam width . Also, there is a limitation that it is impossible to acquire the accurate shape of the target, etc., merely by analyzing the existence of the target, the distance and the moving speed.

On the other hand, the image searcher that acquires and analyzes the infrared or visible light image frequently receives the influence of the atmosphere such as rain, snow, clouds, and mist, and often fails to detect the target.

To overcome this limitation, Synthetic Aperture Radar (SAR) has been developed. SAR is generally used in airplanes or on satellites and can be used to acquire a high resolution high-precision image of the indicator by using the relative change characteristics of the Doppler frequency detected in the received signal by radiating the beam several times on the surface while moving. It means radar. Since SAR utilizes microwave frequencies in the microwave range, it is able to observe land terrain and sea without being affected by the climatic conditions such as haze, snow, rain, snow, clouds and smoke, Because it is a system, images can be obtained regardless of night or day.

SAR is a technique for obtaining an image of a non-moving indicator. The SAR is used to steer the beam in the vertical direction in the traveling direction of the flying object, which is the direction in which the change of the indicator is detected the greatest so that the relative change characteristic of the Doppler frequency is well- . However, if the image is obtained by steer- ing the beam in the vertical direction from the traveling direction of the flying object, since the position of the flying object has already passed the target at the time of detecting the target, it is difficult to apply it to the guided vehicle in which the target must be traced. If the beam is steered toward the traveling direction of the flying object, there is a problem that the angle resolution decreases as the traveling direction of the flying object and the angle between the beam are reduced.

In order to solve the above SAR problem, some guidance vehicles have applied the Doppler Beam Sharpening (DBS) technique to improve the angle resolution (azimuth resolution).

The DBS technique is a technique for applying the SAR technique described above. It is known that the Doppler displacement of the reflected wave is either up-shifted or down-shifted depending on whether the position of the index reflecting the beam is front or back, (generally 19-20) bins by using a Doppler filter based on the characteristic of down-shifting the Doppler frequency of the reflected wave, thereby improving the azimuth resolution and searching forward .

In other words, the DBS technique improves resolution in the azimuthal direction, allowing detection of the target in the forward direction at an angle between the advancing direction and the lateral direction, not the side of the vehicle.

Since the elevation information on the target is not needed in the guidance vehicle for intercepting the target placed on the sea surface like the ship, azimuth resolution and distance resolution are important issues in the explorer. The azimuth resolution can be improved using the DBS technique as described above. However, a method of increasing the distance resolution in the state where the guidance vehicle applies the DBS technique is not proposed, and the pulse compression method is used as in the case of the conventional microwave searcher. Therefore, there is a need for a method to accurately track the target by raising the distance resolution while the guidance vehicle uses the DBS technique.

Korean Registered Patent No. 10-1387664 (Registered April 4, 2014)

It is an object of the present invention to provide a target tracking method of a synthetic aperture radar searcher capable of precisely tracking a target by acquiring a high resolution image with improved azimuth resolution and distance resolution.

According to another aspect of the present invention, there is provided a method for tracking a target of a synthetic aperture radar searcher, the method comprising: in a high resolution mode, a transmitter of the searcher performs a Doppler beam sharpening (DBS ) And a pulse of a stepped frequency waveform (SFW) pulse waveform generated for HRR (High Range Resolution) technique are alternately emitted; The receiver of the searcher distinguishing a pulse corresponding to the DBS pulse waveform and a pulse corresponding to the SFW pulse waveform from a received signal reflected by the alternate beam; Filtering and analyzing a signal corresponding to a pulse corresponding to the DBS pulse waveform according to a predetermined Doppler resolution to obtain a high resolution image; Obtaining a HRR profile for the target from the pulse corresponding to the SFW pulse waveform and comparing the obtained HRR profile with a previously stored reference HRR profile to obtain distance data; And the signal processing unit applying the information of the distance data to the high resolution image to obtain the high resolution image with increased distance resolution; .

Wherein the alternating beam includes alternating pulses of the DBS pulse waveform in which pulses of the same frequency are repeated and pulses of the SFW pulse waveform whose frequency is the same in each pulse and whose frequency linearly increases in accordance with the sequence of radiation, And a pulse waveform that is arranged in a predetermined direction.

The target tracking method radiates the alternate beam in a predetermined reference number in the high resolution mode to obtain a plurality of the high resolution images with increased distance resolution and analyzes the plurality of acquired high resolution images to discriminate the target .

Wherein the target tracking method comprises: before the high resolution mode, the signal processing unit setting an operation mode of the searcher to a DBS mode; Generating a DBS beam composed of the DBS pulse waveform and radiating the DBS beam under the control of the signal processing unit; Filtering the reception signal reflected by the DBS beam according to the Doppler resolution; Analyzing the filtered received signal to obtain a two-dimensional image; Wherein the signal processing unit analyzes the two-dimensional image, sets the region including the target as the target zero if the target is included, and the signal processing unit switches the operation mode of the searcher to the high resolution mode. And further comprising:

Wherein the step of switching to the high resolution mode comprises: setting, as a region of interest, an area determined to include the target so that the searcher searches the ROI in the high resolution mode; And a control unit.

Therefore, the target tracking method of the synthetic aperture radar searcher according to the present invention can be applied to a high-resolution mode for acquiring precise target information, a fixed frequency waveform according to the DBS technique, and a SFW (Stepped frequency waveforms are repeatedly operated to combine the distance data obtained by the distance profile obtained from the distance profile obtained by the HRR method on the high resolution image obtained by the DBS technique to thereby obtain the high resolution image having improved distance resolution as well as the azimuth resolution Can be obtained. Therefore, precise target images can be obtained, so that the target can be accurately detected and tracked.

1 to 4 are views for explaining the DBS technique.
5 is a diagram for explaining a pulse compression technique of the searcher.
6 shows a waveform pattern according to the SFW technique.
FIG. 7 is a graph showing the comparison of the target distinguishing capabilities when the HRR technique is applied and when the HRR technique is not applied.
FIG. 8 shows a target tracking method of a SAR searcher according to an embodiment of the present invention.
9 shows a waveform pattern of a beam in which the SAR searcher of the present invention operates in a high resolution mode.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. However, the present invention can be implemented in various different forms, and is not limited to the embodiments described. In order to clearly describe the present invention, parts that are not related to the description are omitted, and the same reference numerals in the drawings denote the same members.

Throughout the specification, when an element is referred to as "including" an element, it does not exclude other elements unless specifically stated to the contrary. The terms "part", "unit", "module", "block", and the like described in the specification mean units for processing at least one function or operation, And a combination of software.

FIGS. 1 to 4 are diagrams for explaining the DBS technique. FIG. 1 shows an image area obtained according to the beam emission direction and the beam emission in the DBS technique, and FIG. 2 illustrates the relationship between the azimuth angle and the Doppler frequency in the DBS technique. Fig. And FIG. 3 is a diagram for explaining the relationship between the azimuth resolution and the Doppler resolution in the DBS technique.

As shown in FIG. 1, the DBS technique steers and emits a beam in a direction tilted at a steering angle? With respect to the traveling direction of a flying object to obtain an image of a required area. Here, the steering angle [phi] is an angle with respect to the center of the beam, and the emitted beam is emitted with a predetermined beam width centered on the steering angle [phi]. As the steering angle (φ), which is the angle between the flying object and the steering direction of the beam, is small, the resolution of the acquired image is very low because the target does not change significantly. On the other hand, The closer the steering direction of the beam is to the vertical direction, the higher the resolution of the acquired image becomes. Therefore, in order to obtain a high-resolution precise image, it is desirable to acquire an image by steering the beam in the vertical direction in the traveling direction of the air vehicle, such as SAR. However, if an image is acquired by steer- ing the beam in the vertical direction from the traveling direction of the aircraft such as SAR, since the position of the flying object has already passed the target at the time when the target is detected, the target must be detected and tracked as long as possible It is difficult to apply it to a flying object or the like. That is, the smaller the steering angle (φ) is, the more advantageous it is in an induction vehicle. In the DBS technique, as shown in FIG. 1, the steering angle phi of the beam can be set to be less than 90 degrees, but it is preferable that the steering angle is set to 10 degrees or more for the resolution.

The searcher using the DBS technique acquires a two-dimensional image as shown in FIG. In FIG. 1, the x-axis denotes a cross-range in the azimuth direction, and the y-axis denotes a down-range direction.

On the other hand, in FIG. 2, the Doppler frequency F _D is calculated according to Equation 1 according to the angle of incidence ψ of the received signal reflected by the beam emitted at the steering angle φ in the searcher provided in the guidance vehicle .

(Where F _D is the Doppler frequency, v is the moving velocity of the guided vehicle, lambda is the wavelength of the emitted beam, and p is the incident angle of the reflected wave).

Since the moving velocity v of the guidance vehicle in Equation 1 is a verifiable value, the Doppler frequency F _D can be calculated according to the incidence angle of the received signal. This means that the angle of incidence? Of the received signal can be confirmed from the Doppler frequency F _D and the DBS technique measures the Doppler frequency F _D of the entire received signal and measures the measured Doppler frequency F _D) by separating the group in Doppler resolution unit (ΔF _D) is set, a technique to determine the angle of the respective received signal is incident. That is, the azimuth resolution can be increased by using the Doppler resolution (ΔF _D ).

Specifically, the searcher performs a Doppler filtering process for filtering a received signal obtained by reflecting a radiated beam at a predetermined Doppler resolution (ΔF _D ) interval. That is, the Doppler frequency F _D of the total reflection wave is divided into the Doppler resolution (ΔF _D ) magnitude and the received signals corresponding to the Doppler frequencies are distinguished. The relationship between the Doppler resolution (ΔF _D) the received signal incident angle difference (Δψ) and the cross street (cross-range) interval (Δx) according to the same as the equation (2).

(Where R represents the distance from the searcher).

Using equation 1 and 2, and the relationship between the Doppler resolution (ΔF _D) and the cross-distance interval (Δx) is obtained as shown in equation (3).

According to Equation (3), it can be seen that the intersection distance Δx is proportional to the Doppler resolution (ΔF _D ). As the intersection distance? X becomes smaller, the identification ability for the target at the intersection distance, i.e., the x-axis direction is improved, so that the azimuth resolution increases. Therefore, by reducing the size of the Doppler resolution (ΔF _D ) and reducing the intersection distance Δx, the azimuth resolution can be increased.

However, as described above, since the DBS technique improves the azimuth resolution by dividing the Doppler frequency F _D that varies according to the incidence angle ψ in units of a predetermined Doppler resolution ΔF _D , As shown in FIG. 4, the signal waveform of the beam is a pulse repetition frequency (PRF) in which pulse waves of the same frequency are repeatedly output with a time difference of pulse repetition interval (PRI) Should be output. That is, the frequency of the beam emitted from the searcher must be fixed.

5 is a diagram for explaining a pulse compression technique of the searcher.

5 (a) shows a pulse waveform according to a pulse compression technique, and (b) shows a frequency variation of a pulse waveform. As shown in FIG. 5, the pulse compression technique is a method in which a signal obtained by linearly modulating a frequency within a range of a bandwidth (?) In a pulse width section (?) Is radiated into a beam and subjected to matched filtering Is a technique that can increase the peak power and reduce the pulse width by acquiring the pulse compression gain according to? *?.

The distance range (? Y) of the searcher according to the pulse compression technique is calculated according to Equation (4).

(Where c is the speed of light and beta is the bandwidth of the beam).

That is, as the bandwidth? Is increased, the range distance? Y is reduced, and the distance resolution is increased. Therefore, the pulse compression method is used to increase the bandwidth (β) and to increase the distance resolution at the specified pulse width interval (τ).

However, the pulse compression technique frequently fails to provide the appropriate level of distance resolution required for the searcher using the DBS technique with increased azimuth resolution.

In the present invention, a stepped frequency waveform (SFW) technique and a high range resolution (HRR) technique may be further used to increase the distance resolution.

6 shows a waveform pattern according to the SFW technique.

As shown in FIG. 6, unlike the pulse compression method in which the frequency is varied in the pulse in the SFW technique, the frequency is the same in each pulse section, but the frequency of each pulse is linearly increased as shown in equation to be.

(Where f ₀ is the frequency of the initial pulse, f _i is the frequency of the ith pulse, Δf is the frequency increment, and i is a pulse sequence increasing from 0 to n-1, where n is a natural number). )

Since the SFW technique also emits pulses and receives the received signal, the pulse signal s _i (t) emitted according to the SFW technique is defined by equation (6).

(Where t denotes time, s _i (t) denotes a pulse signal, C _i denotes a constant representing the amplitude of the signal specified in accordance with the pulse sequence (i), and θ _i denotes the phase of the pulse signal.

According to Equation (6), the pulse signal _si (t) emits a pulse signal having the same frequency during the pulse width interval? 'At the i-th pulse time T.

The searcher according to the present invention emits a beam whose frequency linearly increases every pulse and acquires a received signal according to the SFW technique. And while the seeker radiates a plurality of pulses, it can further improve accuracy by performing mobility compensation for the distance and velocity at which the seeker is moved.

In order to distinguish the beam emitted according to the SFW technique from the beam emitted according to the pulse compression technique, the beam emitted according to the SFW technique will be referred to as an SFW beam.

In the present invention, the searcher applies the HRR technique to the received signal obtained by radiating and reflecting the SFW beam. The HRR technique is based on the assumption that a reference HRR profile (HRR profile), which is a one-dimensional image projected on a line of sight (LOS) between a radar and a target, that shows the radar cross section (RCS) And comparing the HRR profile obtained from the currently received signal with the stored reference HRR profile to detect the target. The HRR profile is used to accurately identify the target because it is generated differently depending on the geometry and material of the target.

In particular, the HRR profile can be easily obtained by performing Inverse Fast Fourier Transform (IFFT) on the received signal of the searcher using the SFW beam. That is, the HRR profile can be generated by performing mobility compensation on the received signal and then IFFT, and the generated HRR profile can be compared with the previously stored reference HRR profile to easily obtain the target.

After applying the HRR technique, the distance resolution is calculated as shown in Equation (7).

(Where DELTA F represents the inter-pulse frequency interval, and N represents the number of pulses).

Comparing Equation 7, which is the distance resolution according to the HRR technique, and Equation 4, which is the distance resolution according to the pulse compression technique, the bandwidth? Is replaced by the pulse number N * inter-pulse frequency interval? F, By adjusting the number N and the inter-pulse frequency interval? F, it becomes possible to obtain a further improved distance resolution.

In the above description, the frequency of each pulse is linearly increased in the SFW beam. However, in some cases, the SFW technique can be applied even when the pulse frequency of the beam emitted from the searcher varies irregularly. In this case, the receiving unit for receiving the reflected signal may be provided with a frequency reordering unit, and can be restored in a pattern similar to the case where the SFW beam is radiated by rearranging the frequency of the applied reflected signal irregularly so that the frequency is sequentially increased . This reordering method can be applied to the case where the reflection signals are not sequentially received even when the SFW beam is radiated, and the order is changed for various reasons.

FIG. 7 is a graph showing the comparison of the target distinguishing capabilities when the HRR technique is applied and when the HRR technique is not applied.

FIG. 7 is a view showing a result of simulating the case where two targets are present at an adjacent position. In the middle drawing, the left display shows two adjacent targets, and the left side shows an enlarged view. In the middle drawing, the right mark indicates whether or not the target obtained by analyzing the received signal is detected, and shows the case where the HRR technique is not applied. As shown in FIG. 7, when the HRR technique is not applied, only one peak is detected and the two targets arranged adjacent to each other can not be distinguished. On the other hand, referring to the right drawing using the HRR technique, two peaks are detected It is easy to distinguish two targets. That is, when the HRR profile is used, the effect of improving the distance resolution can be obtained, and a plurality of targets existing at the adjacent distance can be discriminated and identified. In the right figure, the X-axis represents the relative distance to the region of interest, and the Y-axis represents the intensity of the received signal.

FIG. 8 shows a target tracking method of a SAR searcher according to an embodiment of the present invention, and FIG. 9 shows a waveform pattern of a beam in which a SAR searcher of the present invention operates in a high resolution mode.

Referring to FIG. 8, in the target tracking method of the SAR searcher of the present invention, the signal processor (not shown) of the searcher operates the searcher in the basic mode (S11). The signal processing unit may set an operation mode in consideration of an operation state of an induction vehicle having a searcher, and may set an operation mode according to a predetermined order according to an operation purpose of the guidance vehicle, or may set an operation mode in response to a user command have.

Here, the basic mode may be a DBS mode as an example. The DBS mode can be used to determine whether the guidance vehicle is moving to a predetermined stopover point or destination on the ground. If the guided vehicle is a guided weapon that intercepts and tracks the target, it should preferably be operated in DBS mode at the beginning of the launch, especially if it is a guided weapon to intercept a target on the ground.

When the basic operation mode is the DBS mode, the signal processor adjusts the steering angle of the beam to be emitted by the searcher to be 10 degrees or more and less than 90 degrees based on the traveling direction of the guidance vehicle, and controls the transmitter (not shown) In order to apply the DBS technique, a beam having a pulse waveform of the same frequency is emitted (S12). In order to apply the DBS technique, a beam having a pulse waveform of the same frequency is referred to as a DBS waveform beam.

Meanwhile, a receiver (not shown) of the searcher performs a Doppler filtering process for filtering the received signal obtained by reflecting and receiving the radiated DBS waveform beam at a predetermined Doppler resolution (ΔF _D ) interval to convert the received signal into an incident angle , And the two-dimensional image is obtained by analyzing the received signals classified by the signal processing unit (S13). Then, the signal processing unit analyzes the two-dimensional image and determines whether the two-dimensional image includes a target (S14).

If it is determined that the target is included in the two-dimensional image, and it is determined that accurate target information acquisition is necessary (for example, the identified target is twice or more the size of the target target) Sets the included region as the ROI, and switches the mode of the searcher to the high resolution mode (S17). The high-resolution mode is a mode for precisely observing the region of interest acquired in the basic mode. In the high-resolution mode, the signal processing unit controls the transmitter of the searcher to alternately emit a signal of a frequency waveform for the DBS technique and a signal of a frequency waveform for the HRR technique (S18).

As described above, when the HRR technique is applied, the distance resolution is improved and the target can be tracked more accurately. However, since the searcher must apply the SFW beam, the pulse frequency of the beam emitted by the searcher must be variable. However, the DBS technique for improving the azimuth resolution requires to emit pulses of the same frequency. Therefore, there is a problem that the HRR technique and the DBS technique can not be utilized at the same time.

In the present invention, as shown in FIG. 9, the signal of the DBS pulse waveform of the same frequency for the BS technique and the signal of the SFW pulse frequency waveform for the HRR technique are alternately emitted. That is, pulse waveforms according to each technique are alternately emitted.

Then, a HRR profile is generated by generating a high-resolution image with improved azimuth resolution from the reflected wave for the beam radiated with the DBS pulse waveform, receiving and analyzing the reflected wave for the beam radiated with the SFW pulse waveform for HRR (S19) .

At this time, the signal processing unit of the searcher may perform the motion compensation first considering the moving distance of the searcher while the alternate beams are radiated sequentially, and then perform the IFFT conversion to obtain the HRR profile.

Thereafter, the signal processing unit compares the generated HRR profile with at least one reference HRR profile previously stored to acquire distance data for the target, and applies the obtained distance data to the ROI in the high resolution image, so that not only the azimuth resolution but also the distance resolution And acquires an enhanced high-resolution image (S20).

The present invention emits alternating beams in which the DBS pulse waveform and the SFW pulse waveform are alternately emitted without first obtaining a high resolution image by radiating the DBS waveform beam and then radiating the SFW beam to generate the HRR profile, And the HRR profile. When a searcher is applied to a high-speed mobile device such as a guided weapon, a DBS waveform beam is radiated to acquire a high-resolution image, and then an HRR profile is generated by radiating an SFW beam. There is a problem that it is difficult to orient the distance resolution of the high resolution image. In order to solve this problem, in the present invention, the DBS pulse waveform and the SFW pulse waveform are alternately radiated, so that a high-resolution image and an HRR profile can be obtained together in one alternate beam emission period. In other words, by acquiring information about the same position, the distance data acquired based on the HRR profile can be easily reflected on the high-resolution image.

On the other hand, the signal processor determines whether the number of times the alternate beams are emitted to obtain a high-resolution image with improved distance resolution is equal to or greater than a preset reference number (S21). If the number of alternate beam emission times is less than the reference number, the signal processing unit again radiates an alternating beam and controls to obtain a high resolution image and an HRR profile. This is to improve target detection accuracy by acquiring a plurality of high resolution images with improved distance resolution. Here, the reference frequency may be set in a range of 2 to 8 times, for example, and may be variable according to the moving speed of a device such as a guided weapon equipped with a searcher.

If the number of times of alternate beam emission is less than the reference number, the signal processing unit can accurately track the target shape and position from the high resolution image having a plurality of improved distance resolutions.

When the target is confirmed, the signal processing unit tracks the identified target (S24).

Accordingly, the target tracking method of the navigator for guidance vehicle according to the present invention emits an alternating beam in which the DBS pulse waveform and the SFW pulse waveform are alternately radiated in the high resolution mode, and acquires a high resolution image according to the DBS pulse waveform of the reflected and received signals The improved distance data is obtained using the HRR profile obtained according to the SFW pulse waveform, and the obtained distance data is reflected on the high resolution image, thereby obtaining a high resolution image having improved azimuth resolution as well as distance resolution. Therefore, the target can be tracked precisely.

The method according to the present invention can be implemented as a computer program stored in a medium for execution in a computer. Where the computer-readable medium can be any available media that can be accessed by a computer, and can also include both computer storage media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, (Digital Versatile Disk) -ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art.

Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (5)

A target tracking method for a synthetic aperture radar (SAR)
A DBS pulse waveform generated according to a Doppler Beam Sharpening (DBS) technique at a beam steering angle designated by the signal processor of the searcher under the control of the searcher in the high resolution mode, and a SFW (High Range Resolution) (Stepped frequency waveform) each pulse of the pulse waveform radiating an alternating alternating beam;
The receiver of the searcher distinguishing a pulse corresponding to the DBS pulse waveform and a pulse corresponding to the SFW pulse waveform from a received signal reflected by the alternate beam;
Filtering and analyzing a signal corresponding to a pulse corresponding to the DBS pulse waveform according to a predetermined Doppler resolution to obtain a high resolution image;
Obtaining a HRR profile for the target from the pulse corresponding to the SFW pulse waveform and comparing the obtained HRR profile with a previously stored reference HRR profile to obtain distance data; And
The signal processing unit applying the information of the distance data to the high resolution image to obtain the high resolution image with increased distance resolution; And the target tracking method of the SAR searcher. 2. The method of claim 1,
The pulse of the SFW pulse waveform in which the frequency of the same frequency is repeated and the pulse of the SFW pulse waveform in which the frequency is the same in each pulse and the frequency is linearly increased in accordance with the order of radiation, Wherein the target tracking method has a waveform. 2. The method of claim 1,
Characterized by radiating the alternating beam at a predetermined reference number in the high resolution mode to acquire a plurality of the high resolution images with increased distance resolution and analyzing the acquired plurality of high resolution images to discriminate the target Target tracking method of explorer. 2. The method of claim 1,
Before the high resolution mode, the signal processing unit sets the operation mode of the searcher to the DBS mode;
Generating a DBS beam composed of the DBS pulse waveform and radiating the DBS beam under the control of the signal processing unit;
Filtering the reception signal reflected by the DBS beam according to the Doppler resolution;
Analyzing the filtered received signal to obtain a two-dimensional image;
Analyzing the two-dimensional image by the signal processing unit to determine whether the target is included; And
Setting an area including the target as an area of interest when the target is included and switching the operating mode of the searcher to the high resolution mode; Wherein the target tracking method further comprises: 5. The method of claim 4, wherein switching to the high resolution mode comprises:
Setting an area determined as containing the target to be an area of interest so that the searcher searches the area of interest in the high resolution mode; And a target tracking unit for tracking the target of the SAR searcher.

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