• The Journal of Korean Institute of Information Technology
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• v.17 no.5
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• pp.47-55
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• 2019

As the damage caused by GPS jamming has been increased, researches for detecting and preventing GPS jamming is being actively studied. This paper deals with a GPS jamming detection method using multiple GPS receiving channels and three-types machine learning techniques. Proposed multiple GPS channels consist of commercial GPS receiver with no anti-jamming function, receiver with just anti-noise jamming function and receiver with anti-noise and anti-spoofing jamming function. This system enables user to identify the characteristics of the jamming signals by comparing the coordinates received at each receiver. In this paper, The five types of jamming signals with different signal characteristics were entered to the system and three kinds of machine learning methods(AB: Adaptive Boosting, SVM: Support Vector Machine, DT: Decision Tree) were applied to perform jamming detection test. The results showed that the DT technique has the best performance with a detection rate of 96.9% when the single machine learning technique was applied. And it is confirmed that DT technique is more effective for GPS jamming detection than the binary classifier techniques because it has low ambiguity and simple hardware. It was also confirmed that SVM could be used only if additional solutions to ambiguity problem are applied.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.962-963
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• 2015

첨단 과학기술의 발전으로 미래전은 정밀타격이 보편화되는 방향으로 발전할 것이며, 이때 정밀유도무기가 적의 핵심표적만을 선별 공격함으로써 빠른 시간 내에 적 전력의 기능을 마비시킬 수 있을 것이다. 그러나 최근 정밀유도무기에 적용되고 있는 GPS 유도방식은 재밍상황에 그 취약성을 들어 낼 수 있다. 따라서 본 논문에서는 GPS 유도방식인 정밀유도무기를 사용하여 공격할 경우 재밍에 대응하기 위한 방편의 하나로 방위각을 제어함으로써 재밍 대응이 가능한지 여부를 실험 및 분석하였다. 분석결과 방위각 140도까지는 제어 가능함을 확인하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.573-575
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• 2015

Positioning system using satellite GPS is used at positioning, navigation, acquisition time information and other various field and taking an important part precision guided weapon such as missile. But commercial code(C/A code) do not have ECCM. Therefore commercial code is vulnerable to various jamming techniques and noise jamming from near station can attack even the encrypted military code(P code) GPS. In this paper, GPS jamming techniques, North Korean GPS jamming cases and anti-jamming GP S technologies are surveyed and described.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.677-682
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• 2016

Recently, because Global Positioning System (GPS) achieves accuracy for engagement of enemy targets, GPS guided weapons have a wide range of applications from land through sea to air. Especially, when GPS guided weapon is then launched, it reads current position and searches a course to the target. As we all know, because GPS signals are weak, these signals can be affected by interference. If jamming signal is strong enough, it can jam the receiver of GPS guided weapon. Therefore, anti-jamming technique is an important thing under these conditions. In this paper, the controlling azimuth angle was used to improve navigation performance of precision guided missile under jamming conditions. First of all, precision missiles by GPS positioning such as SLAM-ER and JDAM were investigated. Also, the azimuth cutoff angle of satellites for usable navigation under jamming signals was analyzed by experimental tests. As a result, we found that azimuth cutoff angle under 140 degree can help ensure continuous GPS reception under the missile guidance.

• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.58-63
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• 2015

Due to GPS signal's vulnerability of jamming attack, various enhancement techniques are needed. Among variety of techniques, we focused on GPS receiver's anti-jamming techniques. There are many anti-jamming methods at GPS receivers which include filtering methods in time domain, frequency domain and space domain. However, these methods are ineffective to signals, which include both jamming and noise. To solve the problem, this paper proposes a jamming separation scheme by using a BSS method in a jamming environment. As separated GPS signals include noise after the jamming separation method, it is difficult to receive accurate GPS signals. For this reason, this paper also proposes a wavelet de-noising method to effectively eliminate noise. Experimental results of this paper are based on a real field test data of an integrated GPS/QZSS/Wi-Fi positioning system. At the end, the simulation result demonstrates its superiority by showing improved positioning accuracy.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.451-456
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• 2016

Because GPS signals are weak, system jamming is a real and present danger. This can happen when the receiver is subjected to intentional or unintentional interference by a transmitter. If the jamming signal is strong enough, the receiver can be operated to take corrective action automatically. Current methods to protect GPS receiver from jamming condition are based on spatial filtering. In this paper, the beamforming as referred to in signal processing technique used in arrays for directional signal reception was suggested and analyzed for anti-jamming. In order to change the directionality of the array when receiving a jamming signal, a beamformer can control the signal at each sensor. Therefore, cutoff angle ${\theta}$ was measured in the opposite direction of the jammer. GPS signals are only processed when the antenna element is within inside the cutoff angle. As a result, GPS positioning can be used in condition under cutoff angle $30^{\circ}$.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.337-339
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• 2013

최근 국내에서는 북한의 사이버 테러로 추정되는 전산망 해킹(APT공격)사건과 더불어 하나의 전자전으로서 GPS 재밍 사건들이 인천 등 서해에서 다수 발생되어 왔다. 즉, 이러한 GPS 재머는 러시아 등에서 유출되는 간단한 장비에서부터 치명적인 대규모 전파공격까지 다양한 형태가 발생될 수 있다. 특히 GPS 정보를 사용하는 선박의 AIS 정보는 다수의 선박으로부터 전송되는 정보로서 재밍 대응 가능한 고가의 장비를 선박측에서 탑재하기 어려우며, 송신지가 인근 북한의 경우 국내에서 근원지를 탐지하더라도 대응이 어려운 실정이다. 따라서 본 논문에서는 GPS 교란의 지능화된 여러 공격 형태를 파악하고, 해상교통관제 시스템에서 자체적으로 실시간 대응할 수 있는 방안을 검토하여 시스템 설계에 반영 하고, 관제사의 실시간 인지를 통한 혼란을 방지하며, 선박에 해당 교란 정보를 제공함으로서 능동적인 관제 방안을 제시한다. 실제적으로 재밍에 대응하는 시스템 설계가 관제에 효율적인 방안인지 확인되어야 하며, 국가적으로도 VTS 서비스의 안전성을 보장하는 기술개발로 진화가 고려되어야 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8C
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• pp.745-757
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• 2007

In this paper, we propose a design of GPS anti-jamming system and its operational method, which can effectively suppress interference and jamming signals induced in GPS receiver. The 7-array antenna used in the proposed system is composed of conventional 6 equi-spaced circular elements with one element on the center of antenna and can be efficiently operated under power-constrained conditions. Futhermore, in this paper, we analyze the structure and complexity of STAP and SFAP which are well known techniques in adaptive array antenna signal processing, and we compare the BER performances between STAP and SFAP in various jamming environment based on the same complexity.

• The Journal of the Korea Contents Association
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• v.15 no.12
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• pp.1-7
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• 2015

These anti-jamming GPS systems are verified using large anechoic chamber or field-test until now. When using a large anechoic chamber, Independent verification from external enviroments like noise is an advantage but high cost and availability of chamber are disadvantages. And in case of field test, verification under real propagation enviroment is an advantage but security problem of military equipments and problem of making same test condition are disadvantages. This paper presents an newly developed anti-jamming GPS test system. This test system mainly consists of small anechoic chamber, jamming divider, jamming signal generator and satellite simulator. The small anechoic chamber is installed many jamming antennas to transmit multi jamming signals and the jamming divider is newly developed to control multi jamming signals. According to self performance test and combined test with Anti-jamming GPS receiver, we verified our system's reliability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1759-1761
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• 2016

In this letter, we propose a GPS repeat-back jamming signal detection scheme based on the sample variance of the horizontal location of a receiver and evaluate the detection performance using real positioning data of the GPS receiver.