KR100866565B1 - Array antenna apparatus and control method of the same in GNSS Anti-jamming system - Google Patents

Abstract

The present invention relates to an efficient array antenna operation scenario and an adaptive digital signal processing method in a global navigation satellite system (GNSS) anti-jamming system, and includes one central element in a conventional six-element circular array antenna. (antenna element) to improve jamming response capability and to operate the element in the ON / OFF form according to whether the initial position information signal is received and whether the jamming signal is present, and the received signal information using the same. The present invention relates to a jamming response for adaptive signal processing. According to the structure of the above-described improved array antenna and its operation scenario, efficient operation can be achieved by reducing power waste of the existing array antenna, and also nulling in the direction of the jamming signal. By increasing the effect, the jamming performance can be improved compared to the conventional array antenna.

Global Navigation Satellite System (GNSS), Anti-jamming, Jamming, Array Antenna Elements

Description

Array antenna apparatus and control method of the same in GNSS Anti-jamming system

1 is a diagram illustrating a general 6-element circular array antenna

2 is a structural diagram of a general Global Navigation Satellite System (GNSS) Anti-jamming system

3A is a diagram illustrating an implementation of a general space-time adaptive processing (STAP) algorithm for adaptive digital signal processing in a GNSS anti-jamming system.

3B is a diagram illustrating an implementation of a general space-frequency adaptive processing algorithm for adaptive digital signal processing in a GNSS anti-jamming system.

4 is a view showing the configuration of an efficient array antenna device (circular array antenna) in the GNSS anti-jamming system according to an embodiment of the present invention

5 illustrates the structure of an improved circular array antenna according to an embodiment of the present invention.

6 is a diagram illustrating an anti-jamming operation scenario when initial position information is known using an improved circular array antenna according to an exemplary embodiment of the present invention.

FIG. 7 is a flowchart illustrating an anti-jamming operation scenario when initial position information of FIG. 6 is known according to an embodiment of the present invention.

8 is a diagram illustrating an anti-jamming operation scenario when initial position information is not known using an improved circular array antenna according to an exemplary embodiment of the present invention.

FIG. 9 is a flowchart illustrating an anti-jamming operation scenario when the initial position information of FIG. 8 is unknown in accordance with an embodiment of the present invention. FIG.

The present invention relates to an array antenna apparatus and method in a GNSS anti-jamming system, and to add one center element to an existing six-element circular array antenna to operate in the absence of jamming signals. Therefore, the present invention relates to an array antenna device for operating an element in an ON / OFF form according to the presence or absence of a jamming signal, and a method using the same.

The Global Navigation Satellite System (GNSS), which is represented by a GPS (Global Positioning System), is a satellite navigation system that receives accurate information about a satellite's position, time, and other errors from satellites and measures accurate visual information and position of the user. GNSS systems are currently used in a variety of land, sea and air systems in the military and civilian sectors. Military use is far more important than civilian use, and is essential for unmanned aircraft takeoffs and precision guided weapons. The GNSS system must be able to receive radio waves from at least four satellites in order to obtain accurate time and location information.

However, it is essential to develop a precision application or military GNSS receiver system that can operate even in the presence of jamming where signal reception from these satellites is fatal. Accordingly, an adaptive antenna that can spatially remove jamming signals has been proposed, but the anti-jamming signal processing technique using only the adaptive antenna has a disadvantage in that performance deteriorates when multipath exists. In addition, a time domain or a frequency domain A technique for removing jamming signals has been introduced by the signal processing in.

At present, it is important to secure technologies for the field of digital signal processing and antenna technology necessary for the development of satellite navigation receiver with jamming capability. Among them, securing the source technology of anti-jamming signal processing technique for array antenna and received signal Systematic research is the most important.

Among the anti-jamming signal processing techniques, the space-time adaptive that compensates for the disadvantages of performance degradation in the presence of multipath with the anti-jamming signal processing technique using only the adaptive antenna capable of removing the spatial jamming signals mentioned above. An anti-jamming signal processing technique using a processing / space-frequency adaptive processing (SFAP) algorithm is discussed.

However, since the anti-jamming technique using the STAP / SFAP algorithm requires a digital signal processing process using the signal of each antenna element, there is a problem that power efficiency is lower than that of the conventional method of removing the jamming signal spatially. In particular, in case of GPS, when the radio wave from the long-distance satellite of 20,000km over the earth arrives at the terrestrial receiver, the power of the radio wave is very weak and it is vulnerable to jamming by jammers. Overcoming jamming with processing gain alone is not enough.

The present invention proposes a structure and operation scenario of an improved circular array antenna capable of efficiently operating an array antenna as an element technology of a global navigation satellite system (GNSS) anti-jamming system. The operation configuration in the absence of jamming signal using the center element, which operates on / off type element according to the presence or absence of jamming signal, has better power efficiency than the existing GNSS anti-jamming method and the accuracy of jamming processed To improve.

According to an embodiment of the present invention for achieving the above technical problem, the array antenna device in the GNSS anti-jamming system adapts to the jamming signal when a jamming signal exists in addition to the received Global Navigation Satellite System (GNSS) signal. Jamming member antenna unit including an antenna element of the optional operation for the type signal processing operation and a jamming member antenna including a minimum specific antenna element for processing the GNSS signal in the absence of a jamming signal in addition to the received GNSS signal Contains wealth.

According to a preferred embodiment of the present invention for achieving the above technical problem, a signal processing method using an adaptive array antenna when initial position information is recognized in a GNSS anti-jamming system is provided with a jamming signal in addition to the received GNSS signal. Beams in the direction of the GNSS signal by turning on the array antenna elements in an adaptive array antenna including additional antenna elements for processing GNSS signals in addition to circular array antenna elements forming a beam and performing nulling in the direction of the jamming signal and turning on the additional antenna element in the adaptive array antenna in the absence of a jamming signal in addition to the received GNSS signal; It includes the step of processing.

According to a preferred embodiment of the present invention for achieving the above technical problem, a signal processing method using an adaptive array antenna when the initial position information is not known in a GNSS anti-jamming system is provided when a jamming signal other than the received GNSS signal is present. In the adaptive array antenna including an additional antenna element for processing GNSS signals in addition to the circular array antenna elements, the circular array antenna elements are turned on and initialized or arbitrarily set. Forming a beam to confirm the direction of the GNSS signal, and when the direction of the GNSS signal is confirmed, forming a beam in the direction of the identified GNSS signal using the circular array antenna elements; Performing nulling in the jamming signal direction and jamming signal unit other than the GNSS signal; And if present, turning on the additional antenna element at the adaptive array antenna to process the GNSS signal.

Hereinafter, with reference to the accompanying drawings, it looks at the configuration of a general GNSS anti-jamming system and then look at the embodiment of the present invention in detail.

1 is a diagram illustrating a general 6-element circular array antenna.

This relates to an array antenna in the GNSS anti-jamming system and represents a structure and operation principle of a general 6-element circular array antenna. The array antenna has a beam formed in a direction of a desired received signal by adaptive signal processing, and operates on a principle of nulling in the direction of a jamming signal. For beam forming, the direction vector is set by the arrival angle θ and the azimuth angle Φ of the desired signal. The direction vector of the circular array antenna is expressed as follows. The direction vector is called an "array manifold vector" and is important in many ways, such as finding a direction of arrival (DOA), beamforming, and array operations.

이다.Where c is the transmission rate of the signal, N is the number of antenna elements, and r is the radius of the circular array. W is the frequency

to be.

2 is a structural diagram of a general Global Navigation Satellite System (GNSS) Anti-jamming system.

Referring to FIG. 2, the anti-jamming system 200 includes an adaptive antenna 201, a space-time adaptive processing (STAP) / space-frequency adaptive processing (SFAP) process 204, a DOA estimator 202, and the like. weight vector estimator 203. The DOA estimator 202 estimates the DOA of the received signal using the signal received by the adaptive antenna 201 and then passes the DOA information of the received signal to the weight vector estimator 203.

Then, the weight vector estimator 203 removes the jamming signal using the DOA of the received signal estimated by the DOA estimator 202 and the code point information received from the GPS (GNSS) receiver, and maximizes the signal power of the desired signal. Estimate the weight vector. The weight vector estimated by the weight vector estimator 203 is used as the weighting coefficient of the receiving space-time vector of the STAP or the receiving space-frequency vector of the SFAP, and the signal vector obtained by multiplying the received signal vector and the weight vector is an accumulator. The combined signal through 205 is a signal from which the jamming signal is removed and becomes an input signal of the GPS (GNSS) receiver 210.

It can be seen that the STAP / SFAP algorithm is applied to the adaptive digital signal processing of each antenna element signal. A detailed description of the STAP / SFAP algorithm will be described below.

3A is a diagram illustrating an implementation of a general space-time adaptive processing (STAP) algorithm for adaptive digital signal processing in a GNSS anti-jamming system.

This shows the structure of STAP method for eliminating jamming. It is a method of eliminating jamming signal by introducing FIR filter of transversal filter concept to each antenna element of array antenna, and FIR filter coefficients of each array antenna are input to array antenna. The weight vector is estimated using a space time signal vector, which is a combination of spatial signals and temporal signals for the FIR filter, and the estimated weight vector is applied as the FIR filter coefficient of each array antenna to remove the jamming signal. .

FIG. 3B is a diagram illustrating an implementation of a general space-frequency adaptive processing algorithm for adaptive digital signal processing in a GNSS anti-jamming system.

This shows the structure of the SFAP method for jamming elimination. The SFAP method removes jamming through adaptive signal processing in the frequency domain by applying Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) to each antenna array. In this way, the signals received by each array antenna are stored in a buffer of the FFT size and then converted into signals in the frequency domain through the FFT, and the weight vector is the spatial signals input to the array antenna and the frequency domain signals after passing the FFT. It is estimated using the space frequency signal vector, which is a combination of the two. The estimated weight vector is applied as a coefficient of each frequency bin to remove the jamming signal.

However, the above-mentioned STAP / SFAP method can compensate for the deterioration of the performance deterioration in the presence of multipath of the anti-jamming signal processing technique using only an adaptive antenna capable of removing the spatial jamming signal. As mentioned, STAP and SFAP type digital signal processing process is required by using the signal of each antenna element, so it is much deteriorated in power efficiency compared to the conventional method of removing jamming signal and moves to the target using limited power. In order to do so, the mobile platform requires a large power.

Therefore, in the following to improve the above disadvantages to look at the efficient array antenna device and method in the GNSS anti-jamming system of the present invention.

4 is a view showing the configuration of an efficient array antenna device (circular array antenna) in the GNSS anti-jamming system according to an embodiment of the present invention.

Referring to FIG. 4, the efficient array antenna device 400 may include antenna elements of an optional operation for adaptive signal processing operation for the jamming signal when a jamming signal exists in addition to the received Global Navigation Satellite System (GNSS) signal. An jamming presence antenna unit 410 is included and a jamming member antenna unit 420 including a minimum specific antenna element for processing the GNSS signal in the absence of a jamming signal in addition to the received GNSS signal.

Herein, the antenna elements in the jamming presence antenna unit 410 are six elements of a circular array antenna, and the specific antenna element in the jamming member antenna unit 420 is An additional antenna element located in the middle of the antenna elements of the jamming presence antenna section 410.

In order to improve the efficiency of jamming, even when there is a jamming signal in addition to the GNSS signal, the specific antenna element of the jamming member antenna unit 420 is operated together with the antenna elements of the jamming presence antenna unit 410 to remove jamming. Do it.

5 is a view showing the structure of an improved circular array antenna according to an embodiment of the present invention.

This represents the structure of the improved circular array antenna and the operation principle in the presence of a jamming signal. As an example of the efficient array antenna device shown in FIG. 4, the conventional six-element circular array antenna is used. It further relates to a 7-element circular array antenna having one center antenna element.

The improved 7-element circular array antenna is the same as the operation principle of the six-element circular antenna device in the presence of a jamming signal, but one center antenna element added when the jamming signal is not present ) Can be operated in ON / OFF mode depending on the presence of jamming signal.

In other words, if there is a jamming signal, the circular array antenna around the center element is turned on to perform an adaptive signal processing operation, and if the jamming signal is not present, the jamming signal is removed. It is a method of receiving a GNSS signal using only the center element.

The structure of the anti-jamming system to which the improved array antenna device is applied and the structure of STAP and SFAP, which are adaptive digital signal processing technologies, are the same in FIGS. 2, 3A, and 3B. Is the same as described above. The improved operation of the circular array antenna has the advantage of eliminating power waste caused by adaptive signal processing that operates even when no jamming signal exists in the existing array antenna device. In addition, the use of seven antenna elements improves the nulling performance compared to the existing 6-element circular array antenna, thereby achieving more robust jamming performance.

Now, it is necessary to consider a method of processing jamming signals using an improved array antenna device, which is largely unknown when the direction of the initial GNSS signal is unknown, the direction of the initial GNSS signal, and the initial Operational scenarios can be divided into those affected by jamming signals and those not received after orientation.

FIG. 6 is a diagram illustrating an anti-jamming operation scenario when initial position information can be known using an improved circular array antenna according to an exemplary embodiment of the present invention.

This shows an operation scenario when the initial location information can be known, and the initial location information can be classified into a sleep mode and an anti-jamming (AJ) mode. Sleep mode is a mode in which the mobile platform set the initial position is not affected by the jamming signal, and turns off six elements except the center element among the seven elements and receives the GNSS signal using only the center element. Done. If the jamming signal does not exist with the setting of the sleep mode, power usage may be minimized by not performing the adaptive signal processing operation.

AJ mode is a mode that performs beamforming in the direction of a received signal and nulling in the direction of a jamming signal when a mobile platform having an initial position set is affected by a jamming signal. This mode is to turn on the element and perform anti-jamming digital signal processing by applying STAP / SFAP method. That is, the jamming signal is removed through the AJ mode. After that, when the jamming signal is not affected again, the jamming signal is switched back to the sleep mode to minimize power usage.

FIG. 7 is a flowchart illustrating an anti-jamming operation scenario when initial position information of FIG. 6 is known according to an exemplary embodiment of the present invention.

This shows an operation scenario when the position information of the initial GNSS signal is known. Referring to FIG. 7, when a jamming signal exists in addition to the GNSS signal received first (701), circular array antenna elements (circular array) In the adaptive antenna including an additional antenna element for processing other GNSS signals, the circular array antenna elements are turned on to form a beam in the direction of the GNSS signal and the jamming signal. Nulling is performed in the direction of 702. However, when a jamming signal is not present in addition to the received GNSS signal (701), the adaptive antenna turns on the additional antenna element to process the GNSS signal (703).

In the adaptive antenna, the additional antenna element is located in the middle of six six-element circular array antennas, and performing the quenching in the direction of the jamming signal is the aforementioned space-time adaptive. use a processing / space-frequency adaptive processing (SFAP) algorithm.

Also, when forming a beam in the direction of the GNSS signal and performing nulling in the direction of the jamming signal, the adaptive antenna turns on the circular array antenna elements and the additional antenna element to beam in the direction of the GNSS signal. And pressing in the direction of the jamming signal.

8 is a diagram illustrating an anti-jamming operation scenario when initial position information is not known using an improved circular array antenna according to an exemplary embodiment of the present invention.

This shows an operation scenario when the initial position information is unknown, and when the initial position information is unknown, it is largely divided into a nulling mode, an anti-jamming mode, and a sleep mode. Nulling Mode is a mode that turns on six elements around a center element and performs anti-jamming digital signal processing by applying STAP / SFAP method, but because the initial position information is not known due to the influence of the initial jamming signal, The direction is a mode that forms beams in the initial DOA and removes jamming signals.

When the direction of GPS (GNSS) signal is found through the operation of the nulling mode, the system transitions from the nulling mode to the AJ mode.After that, when the signal is not affected by the jamming signal again, it switches back to the sleep mode to minimize the power usage. It is operated by. Therefore, the improved circular array antenna has the advantage of minimizing the power waste caused by adaptive signal processing that operates even when there is no jamming signal by setting the sleep mode that does not exist in the existing circular array antenna through the center element. have.

In detail, the jamming performance of the improved circular array antenna is superior to that of the conventional circular array antenna by comparing the performance of the conventional circular array antenna structure and the improved circular array antenna structure.

First, the parameters for the simulation are shown in Table 1 below.

Chip rate 1.023Mcps PRN code C / A code Modulation BPSK Spreading Factor 20460 Antenna Array Conventional 6 element circular Linear Array Enhanced 7 element circular Linear Array Jamming signal Wideband jamming

Tables 2 and 3 below show the SINR (Signal-to-Interference and Noise Ratio) and BER (Bit) according to the jamming power of the conventional 6-element circular array antenna structure and the improved 7-element circular array antenna structure in a single jammer environment. Error rate) performance comparison. As shown in the performance of Table 2 and Table 3, when the maximum jamming power is increased to 60dB of the GNSS signal, the improved 7-element circular array antenna structure shows better jamming performance than the conventional 6-element circular array antenna structure. You can check it.

The SINR and BER performance comparisons in a single jammer environment are as follows.

Table 4 and Table 5 compare the SINR and BER performance according to the jamming power of the conventional 6-element circular array antenna structure and the improved 7-element circular array antenna structure in the presence of two jamming signals. Table 7 compares the SINR and BER performance according to the jamming power of the conventional 6-element circular array antenna structure and the improved 7-element circular array antenna structure in the presence of three jamming signals.

The SINR performance comparison and BER performance comparison in two jammer environments are as follows.

The SINR and BER performance comparisons in three jammer environments are as follows.

As a result of the performance verification, the structure of the improved 7-element circular array antenna is improved when the maximum jamming power is increased to 60 dB of the GNSS signal even in the environment where the two or three jamming signals exist as well as the performance in the single jammer environment. It can be seen that the jamming performance is superior to that of the 6-element circular array antenna structure. Through this, it can be seen that the improved 7-element circular array antenna structure is superior to the conventional 6-element circular array antenna in terms of power efficiency and jamming performance.

FIG. 9 is a flowchart illustrating an anti-jamming operation scenario when initial position information in FIG. 8 is unknown according to an exemplary embodiment of the present invention.

This represents an operation scenario when the initial position information of the GNSS signal is unknown. Referring to FIG. 9, circular array antenna elements are present in the presence of a jamming signal other than the received GNSS signal (901). After the antennas are turned on in an adaptive antenna including an additional antenna element for processing GNSS signals in addition to the antenna elements and forming a beam in an initialized or arbitrarily set direction The direction of the GNSS signal is checked (902).

When the direction of the GNSS signal is confirmed, a beam is formed in the direction of the identified GNSS signal using the circular array antenna elements, and nulling is performed in the direction of the jamming signal (903). . However, in the absence of the jamming signal other than the GNSS signal (901), the adaptive antenna is turned on to process the GNSS signal (904).

Here, when the direction of the GNSS signal is confirmed (902), the circular antenna element and the additional antenna element are turned on together in the adaptive antenna to confirm the direction of the GNSS signal, and the direction of the GNSS signal is confirmed. In the case where the circular array antenna elements and the additional antenna element are used together, a beam is formed in the direction of the identified GNSS signal and the antenna is pressed in the direction of the jamming signal (903).

The invention can also be embodied as computer readable code on a computer readable recording medium. Computer-readable recording media include all kinds of recording devices that store data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disks, optical data storage devices, and the like, which are also implemented in the form of carrier waves (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. In addition, functional programs, codes, and code segments for implementing the present invention can be easily inferred by programmers in the art to which the present invention belongs.

Such a method and apparatus of the present invention have been described with reference to the embodiments shown in the drawings for clarity, but these are merely exemplary, and various modifications and equivalent other embodiments are possible to those skilled in the art. Will understand. Therefore, the true technical protection scope of the present invention will be defined by the appended claims.

An efficient array antenna apparatus and a processing method using the same in the GNSS anti-jamming system of the present invention are the structure of an improved circular array antenna in which a center antenna element is added to an existing 6-element circular array antenna and an operation scenario thereof. Efficient operation is possible by reducing power waste of existing array antennas, and also improves jamming performance by increasing the nulling effect in the jamming signal direction. This improvement in power efficiency and jamming performance has the effect of improving the efficiency and accuracy of platforms equipped with GNSS anti-jamming systems.

Claims (5)

Adaptive array antenna including additional antenna elements for processing GNSS signals in addition to circular array antenna elements when jamming signals are present in addition to the received Global Navigation Satellite System (GNSS) signal A jamming presence antenna unit configured to turn on the circular array antenna elements to form a beam in the direction of the GNSS signal and to null in the direction of the jamming signal; And A jamming member antenna unit configured to process the GNSS signal by turning on the additional antenna element in the adaptive array antenna in the absence of a jamming signal in addition to the received GNSS signal; a GNSS anti-jamming system comprising a Array antenna device in. The antenna of claim 1, wherein the jamming presence antenna unit In the presence of the jamming signal, the additional antenna element is turned on together to form a beam in the direction of the GNSS signal and to perform nulling in the direction of the jamming signal. Array antenna device in jamming system. In the signal processing method when the initial position information is recognized in the Global Navigation Satellite System (GNSS) Anti-jamming system, In the presence of a jamming signal in addition to the received GNSS signal, the circular array antenna in an adaptive array antenna including an additional antenna element for processing GNSS signals in addition to the circular array antenna elements. Turning on elements to form a beam in the direction of the GNSS signal and nulling in the direction of the jamming signal; And And in the absence of a jamming signal in addition to the received GNSS signal, processing the GNSS signal by turning on the additional antenna element in the adaptive array antenna. Antenna control method. In the signal processing method when the initial location information is unknown in the Global Navigation Satellite System (GNSS) Anti-jamming system, The circular array antenna elements in an adaptive array antenna including an additional antenna element for processing GNSS signals in addition to the circular array antenna elements in the presence of a jamming signal other than the received GNSS signal. Checking the direction of the GNSS signal by turning on and forming a beam in an initialized direction or a predetermined direction; When the direction of the GNSS signal is confirmed, forming a beam in the direction of the identified GNSS signal using the circular array antenna elements and performing nulling in the direction of the jamming signal; And And processing the GNSS signal by turning on the additional antenna element in the adaptive array antenna in the absence of the jamming signal other than the GNSS signal. Way. The method of claim 3, wherein In the presence of the jamming signal, the additional antenna element is turned on together to form a beam in the direction of the GNSS signal and to perform nulling in the direction of the jamming signal. Array antenna control method in jamming system.

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