KR101619064B1 - Target tracking method using active clutter map - Google Patents

Abstract

The present invention discloses a target detection method using an active clutter map. A method for detecting a target using an active clutter map according to the present invention is characterized by comprising the steps of: storing a first clutter map storing a first clutter signal in the absence of a target; Generating an adaptive clutter signal for filtering the clutter contained in the received signal via a clutter map, generating a threshold signal of the target based on the received intensity of the received signal that is different for each of the distances, Generating a final critical signal by combining the clutter signal and the critical signal, and detecting a signal section forming the final critical signal abnormality from the received signal as a target signal.

Description

[0001] The present invention relates to an active clutter map,

The present invention relates to a target detection method using an active clutter map, and more particularly, to a target detection method using an active clutter map that efficiently and accurately detects a target among received signals of a radar system.

The radar having a beam width of an acute angle, for example, adopts the FM-CW method, but is limited to the forward surveillance at a distance of several tens to several hundred meters by simultaneous transmission and reception isolation.

Recently, attention has been paid to a near-field, wide-angle radar that monitors targets such as the front and rear sides. However, since the beam width is wide, it is easy to detect a large number of targets among the fixed clutter, It is not.

In order to detect a target from a received signal of a radar, it is necessary to sufficiently suppress the clutter in the search area. When the clutter suppression becomes insufficient, it is difficult to accurately detect the target because the unnecessary reflection object and the target can be confused.

Pulse integration and MTI (Moving Target Indicator) are widely used as a method of using the Doppler frequency for such clutter suppression. The pulse integral method suppresses the clutter by repeatedly transmitting a short pulse and integrating the reflected wave or the range profile (signal response of the range bin) from the object for each pulse.

As another method, there is a method of measuring the Doppler frequency of a target, removing only the fixed clutter on the frequency axis by the notch filter, and a method of removing the fixed clutter in space by controlling the narrow antenna beam using the array antenna It is known.

However, in order to accurately detect the target from the received signal in consideration of the clutter effect that suddenly appeared due to the influence of the surrounding environment rather than the fixed clutter, or to accurately detect the target even when the target is located in the region where the clutter component exists, It is not easily solved by one prior art, and it is necessary to improve such a part.

Korean Registered Patent No. 10-120344 (Nov. 14, 2012)

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a method and a system for detecting a target clutter in a radar system using a default clutter map and an active clutter map updated every predetermined period And a method of detecting a target using an active clutter map that efficiently and accurately detects a target.

The objects of the present invention are not limited to the above-mentioned problems, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a method of detecting a target using an active clutter map, the method comprising: obtaining a first clutter map storing a first clutter signal in the absence of a target; Generating an adaptive clutter signal for filtering the clutter contained in the received signal through an active clutter map storing the two clutter signals, generating an adaptive clutter signal based on the threshold of the target, Generating a final critical signal by combining the adaptive clutter signal and the critical signal, and detecting a signal section forming the final critical signal abnormality from the received signal as a target signal do.

The threshold signal may be changed according to the radar height of the radar system.

When the target is a plurality of targets, the threshold signal of each target among the plurality of targets can be corrected based on the cancellation index in which the received signal is canceled while passing through a plurality of targets.

Therefore, in the present invention, there is an advantage that the target can be efficiently and accurately detected from the received signals of the radar system using the default clutter map in the absence of the target and the active clutter map updated every predetermined period.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the claims.

1 is an exemplary view showing a relationship between a radar system and a target of the present invention.
2 is a block diagram illustrating the radar system of Fig.
3 is a block diagram showing the transmitter of FIG. 2 as an embodiment.
FIG. 4 is a block diagram showing the receiver of FIG. 2 as an embodiment.
5 is a flowchart illustrating a target detection process according to an embodiment of the present invention.
FIG. 6 is an exemplary diagram showing the discrimination of the reception signal of the present invention as an embodiment.
7 is an exemplary diagram showing another embodiment of the determination of the received signal of the present invention.
8 is an exemplary diagram showing another embodiment of the determination of the reception signal of the present invention.
FIG. 9 is a flowchart showing an operation of the radar system of FIG. 1 as an example.
10 is a flowchart showing the step S100 of FIG. 9 as a concrete example.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Further, the embodiments described herein will be described with reference to cross-sectional views and / or schematic drawings that are ideal illustrations of the present invention. Thus, the shape of the illustrations may be modified by manufacturing techniques and / or tolerances. In addition, in the drawings of the present invention, each component may be somewhat enlarged or reduced in view of convenience of explanation.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exemplary view showing a relationship between a radar system and a target of the present invention.

Referring to FIG. 1, a radar system 100 efficiently and accurately detects a target from a received signal of a radar system 100 using a default clutter map in the absence of a target and an active clutter map updated every predetermined period And the like.

Here, the radar system 100 is a device that uses radio frequency signals to determine the search, tracking, and position information of a target that has come into a surveillance area. In the radar system 100, a radio frequency signal is transmitted to a target, and the radiated waves are acquired for the distance, direction, and altitude of the target, and then returned to the radar system 100.

The term "clutter" as determined by the radar system 100 means a reflection obstacle such as an echo caused by unnecessary reflected waves generated from the ground, sea surface, raindrops, etc. in the radar, It means visual notation.

For example, sea surface clutter is influenced by wave height, wind direction, and antenna height, and raindrop clutter is a noise phenomenon on the screen that is affected by rainfall, snowfall, and fog.

In general radar, climatic targets such as raindrops are regarded as clutters. In weather radar, ground, aircraft, etc. are treated as clutters. That is, the clutter setting can also be changed depending on which target of the radar system 100 is.

2 is a block diagram illustrating the radar system of Fig.

Referring to FIG. 2, the radar system 100 includes a transmitter 110, a receiver 120, and a controller 130.

The transmitting unit 110 transmits a radio frequency signal for detecting a target in the surveillance region, and the receiving unit 120 receives a reception signal that is a radio wave reflected from the target and clutter after being transmitted by the transmitting unit 110 do.

For example, when the radar system 100 is equipped with an IR-UWB radar, the radar system 100 may include a transmitter 110 as shown in FIG. 3 and a receiver 120 as shown in FIG. .

3, the transmitter 110 includes a transmission antenna 111, a pulse generator 112, a synchronizer 113, a clock generator 114, a code generator 115, a modulator 116, and a first interface 117).

Data to be transmitted to the surveillance region is input to the transmission unit 110 through the first interface 117.

Converted into the data modulated through the modulator 116 input to the first interface 117 and the data modulated with the encryption code output from the code generator for the enciphering process is input to the synchronizer 113 .

The synchronizer 113 synchronizes the modulated data with the above-described encryption code based on the reference clock provided from the clock generator.

Thereafter, the pulse generator 112 generates the synchronization data provided from the synchronizer 113 as a pulse signal, and provides the generated pulse signal to the transmission antenna 111. [

The transmitting antenna 111 transmits the pulse signal provided from the pulse generator to the monitoring area which is in directivity.

4, the receiving unit 120 includes a receiving antenna 121, a correlator 122 (including a multiplexer 122-1, an integrator 122-2, and a S / H 122-3) A clock generator 123, a synchronizer 124, a clock generator 125, a signal processor 126, a second interface 127 and a code generator 128.

In addition, when the radar system 100 further includes a transmitting / receiving switch, the transmitting unit 110 and the receiving unit 120 are not separately provided as described above, but may be integrally provided.

The receiving unit 120 receives the reception signal, which is a radio wave reflected by at least one of the target and the clutter after being transmitted by the transmission unit 110, processes the reception signal in a form that can be determined, And transfers the received signal to the control unit 130. [

5 is a flowchart illustrating a target detection process according to an embodiment of the present invention.

5, the control unit 130 detects a target signal from a received signal received by the receiving unit 120, and also executes a pre-processing for detecting a target signal from a received signal.

That is, the control unit 130 receives the received signal from the receiving unit 120, and removes the clutter, which is a background noise, in order to detect the target from the received signal (b). For example, the controller 130 may use a loop-filter algorithm and an SVD algorithm to remove the clutter.

Thereafter, the controller 130 determines the degree of similarity between the original signal stored as a sample and the received signal A removed from the clutter, extracts a reflection signal for the target from the determination result, and outputs the extracted reflected signal It is possible to determine the distance between the radar systems 100 (d).

After that, the controller 130 can continuously correct the distance information while tracking the motion characteristic of the determined target (e). At this time, the controller 130 can track the motion characteristics of the target by using the Kalman-filter algorithm.

FIG. 6 is an exemplary diagram showing the discrimination of the reception signal of the present invention as an embodiment.

Referring to FIG. 6, the radar system 100 may cause an error that recognizes noise as a target due to an instantaneous noise component.

Even if the process of removing clutter and other noise from the received signal is preceded, there may be a signal component having a relatively large value of the RCS (Rader Cross Section) and an irregularly existing clutter signal component.

In particular, the target may act as an obstacle. That is, when the position of the radar system 100 is referred to, the signals traveling from the back of the target to the radar system 100 are relatively weaker than the signals reflected to the target and transmitted to the radar system 100, It may be an error factor for more accurately detecting the target.

6, when the target ① moves in front of the object ② having a large RCS value, the signal value of the object ② fluctuates. As a result, An error that the object (2) is judged to be a different target may occur.

7 is an exemplary diagram showing another embodiment of the determination of the received signal of the present invention.

Referring to FIG. 7, the radar system 100 may include a fixed clutter map.

When a fixed clutter map is applied, it may not be easy to accurately detect the target when the target is located at a relatively large clutter position or when the environment of the monitoring area is changed by removing the stationary clutter.

As shown in FIG. 7, when the target (1) is located in the section C where no other clutter component exists, the radar system 100 calculates the target (1) and The target (1) can be easily detected.

However, when the target (2) is located in the section K where the clutter component is relatively large by the clutter (2) and the clutter (3), the radar system 100 detects the target (2) Not only the signal components including the clutter (2) and the clutter (3) are mixed and the signal component of the target (2) is not clearly distinguishable from the corresponding section of the fixed clutter map Therefore, the target (2) may not be detected.

8 is an exemplary diagram showing another embodiment of the determination of the reception signal of the present invention.

8, each signal component for the target (4), clutter (2) and clutter (3) located behind the target (1) on the basis of the position of the radar system (100) The signal intensity is transmitted to the radar system 100 in a state that the signal strength is reduced due to the radio wave interference due to the presence of the radio wave (1). Therefore, it may not be detected that the target (4) exists in the signal section in which the target (4), the clutter (2) and the clutter (3) exist.

However, if there is no target, the control unit 130 of the radar system 100 transmits a pulse signal to the surveillance region and receives a preliminary signal, which is a reflection signal thereof, to check the clutter state existing in a fixed state in the surveillance region Generates a first clutter signal, and manages a default clutter map storing the generated first clutter signal.

In addition, the control unit 130 generates a second clutter signal by receiving a preliminary signal, which is a reflection signal thereof, after confirming the state of the added clutter in the surveillance region, , And manages an active clutter map for storing the generated second clutter signal.

The control unit 130 generates an adaptive clutter signal capable of filtering the clutter included in the received signal for detecting the target of the surveillance region using the default clutter map and the active clutter map. That is, the controller 130 may store the clutter as an adaptive clutter signal at every cycle, and may set the minimum value of the adaptive clutter signal for each clutter sample.

The controller 130 calculates the reception intensity of the target reception signal according to the distance and outputs the threshold signal of the target (that is, it can be expressed as Threshold a (t)) to a value lower than a predetermined level lower than the calculated reception intensity .

Here, a (t) of the threshold a (t) can be set to a value that changes according to the height of the radar and the distance of the target. That is, when the height of the radar is increased, the reflection area of the target is changed. Therefore, if the signal intensity considering the distance of the target according to the height of the radar is calculated, the threshold signal (i.e., the threshold a can do.

Further, when there are a plurality of targets, a signal passing through the target can be canceled. As a result, the second target positioned behind the first target relative to the radar system 100 is formed as a signal having a smaller signal magnitude relative to the first target, so that a threshold value corresponding to the position and distance of each target In other words, it is necessary to increase detection accuracy for each target.

That is, when the number of targets is plural, the control unit 130 preferably corrects the threshold signal of each target among the plurality of targets based on the cancellation index where the received signal is canceled while passing through a plurality of targets.

The control unit 130 generates a final threshold signal combining the adaptive clutter signal and the threshold signal and applies the final threshold signal generated in this way to the received signal, As shown in FIG.

Here, the applied clutter signal can be set to the minimum value as mentioned above, and the final threshold signal can be expressed as follows.

Threshold C (t) = Min (C _d , C _a ) + a (t)

(C (t): final threshold signal, C _d : first clutter signal, C _a : second clutter signal, a (t)

As shown in Fig. 8, the control unit 130 can clearly detect each target of the plurality of targets by comparing the received signal with the final threshold signal. That is, the control unit 130 can easily detect the target (1) and the target (4) as a result of detecting the signal section (e.g., D, E) forming the final critical signal abnormality in the received signal as the target signal.

FIG. 9 is a flowchart showing an operation of the radar system of FIG. 1 as an example.

Referring to FIG. 9, the radar system 100 includes a primary clutter map storing a first clutter signal in the absence of a target, and an active clutter storing a second clutter signal, And generates an adaptive clutter signal for filtering the clutter included in the received signal through the map (S100).

Thereafter, the radar system 100 generates a threshold signal of the target based on the reception intensity of the received signal which is different for each distance (S200).

Thereafter, the radar system 100 generates a final threshold signal combining the minimum value of the adaptive clutter signal and the threshold signal of the target by distance (S300).

Thereafter, the radar system 100 detects a signal section forming a final critical signal abnormality among the received signals while monitoring the surveillance region as a target signal (S400).

Then, the above-mentioned steps are repeated until the operation of the radar system 100 is terminated (S500).

FIG. 10 is a flowchart showing the step S100 of FIG. 9 as a concrete example.

Referring to FIG. 10, the step of generating an adaptive clutter signal uses a default clutter map and an active clutter map, as described above.

The active clutter map may be implemented as a result of conducting a clutter search every predetermined period, or as an example, performing a clutter search every target search period.

According to the above example, the step of generating the adaptive clutter signal may be classified based on whether or not the target exists (S102).

In step S102, when there is a target, a second clutter signal that is updated as a result of conducting a clutter search at a predetermined period is generated (S104), and the active clutter map is updated using the generated second clutter signal (S106).

In step S102, when there is no target, a first clutter signal is searched for a clutter that is fixed in the monitoring area (S108), and a default clutter map is stored using the generated first clutter signal (S110).

Thereafter, the radar system 100 adjusts the clutter contained in the received signal as a result of monitoring the surveillance region using the updated active clutter map in step S106 and the default clutter map managed in step S110. Type clutter signal (S112).

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

In addition, since the present invention efficiently and accurately detects a target in a received signal of a radar system using a default clutter map in the absence of a target and an active clutter map updated every predetermined period, Is not only sufficient but also practically usable because it can be practically carried out clearly.

100: radar system 110: transmitter
111: transmitting antenna 112, 123: pulse generator
113, 124: synchronizer 114, 125: clock generator
115, 128: code generator 116: modulator
117: First interface 120: Receiver
121: Receive antenna 122: Correlator
122-1: multiplexer 122-2: integrator
122-3: S / H 126: Signal processor
127: second interface 130:

Claims (3)

A method for detecting a target of a radar system,
A clutter contained in a received signal is filtered through an active clutter map storing a default clutter map storing a first clutter signal in the absence of a target and a second clutter signal searching for clutter every predetermined period Generating an adaptive clutter signal for the adaptive clutter signal;
Calculating a reception intensity of the signal corresponding to the target by being divided by a distance and generating a threshold signal of the target based on the calculated reception intensity;
Generating a final threshold signal combining the adaptive clutter signal and the threshold signal; And
And detecting a signal section forming the final critical signal abnormality from the received signal as a target signal. The method according to claim 1,
Wherein the threshold signal is changed according to a radar height of the radar system. 3. The method according to claim 1 or 2,
And an active clutter map for correcting a critical signal of each target among the plurality of targets based on a cancellation index in which the received signal is canceled while passing through a plurality of targets when the target is a plurality of targets.

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