• 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.

• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.46-51
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• 2015

In this paper, I design a linear array antenna simulator for anti-jamming GPS systems and perform various performance analysis by simulation. First, I generate simulated transmission signals through the analysis of GPS satellite signal structure, and analyze SNR(Signal to Noise power Ratio) performance of linear array antenna according to number of arrays under noise environments. In addition, I analyze the performance of the anti-jamming beam pattern using MMSE(Minimum Mean Square Error) signal processing method, and also analyze the anti-jamming performance considering antenna calibration problem when there are different delays between arrays.

• Journal of the Korea Society of Computer and Information
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• v.16 no.5
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• pp.101-107
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• 2011

The optimum weight vector is studied to remove interference and jamming signals in adaptive array antenna system. The optimum weight vector is calculated to apply a minimum variance algorithm and cost function in linearly constrained conditions, and accurately estimates target's signal. Adaptive array antenna system is the system which improves signal to noise ratio(SNR) and decreases interference and jammer power. Adaptive array antenna system delays at tap output of antenna array element. Each tap finally makes the complex signal of one in multiplier complex weight. In order to obtain optimum's weight calculation, optimum weight vector is used in this paper. After simulation, resolution is increased below $3^{\circ}$, and sidelobe is decreased about 10 dB.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.507-511
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• 2010

Digital Radio Frequency Memory (below, DRFM) performs RF signal data store, delay and re-transmission. DRFM is wildly used as core module of Jammer, EW simulator, Target Echo Generator etc. This paper suggests a hardware design of DRFM which is composed RF section(RF Input/Output Module, Local Oscillator Module) and Digital section(ADC module, memory, DAC module), and confirm the validity of the propose by the test result.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11A
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• pp.924-932
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• 2011

In this paper, we propose a possibility of usage of carrier superpositioning scheme for a specific slow frequency hopping(SFH) transmission method for the satellite data link in which all of hopping carriers have to be synchronized to DSM transponder of our previous work and usage of frequency diversity in the saved frequency to overcome the SFH disadvantage against jammer. We have analyzed anti-jamming performance and LPI performance and confirmed that the proposed scheme can support data service with 18.5dB processing gain against the worst case partial band jamming and give 2.5dB gain in the LPI performance against D&M detector which can estimate the data rate of unknown signals.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.12
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• pp.1216-1227
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• 2013

GNSS(Global Navigation Satellite System) is now being widely used in both civilian and military applications where accurate positioning and timing information are required and it is considered as a representative convergence technique in IT-Military application techniques. However, GNSS has low sensitivity level of GNSS receivers and is vulnerable to jamming signal, since the signals come from the satellite located at approximately 20,000 Km above the earth. The studies for the anti-jamming techniques in military applications have been passively performed in the domestic, because the information related GNSS are dependent on the countries that have GNSS. In this paper, we show the effect of jammer ERP by analyzing the link budget of GPS J/S power as a function of distance between jammer and receiver. Also, we categorize the anti-jamming techniques based on the functional block diagram of GNSS receiver structure and analyze the recent anti-jamming GNSS products and their technologies developed in domestic and foreign countries.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.7
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• pp.576-579
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• 2017

Due to the existence of flash lobe caused by the radome structure, a radar return in general contains clutter component added to target echo. Unlike jammer, clutter is apt to simultaneously coexist with target echo, which hinders a monopulse radar from estimating the angle difference between target echo direction and radar steering direction. In this paper, we propose a clutter estimation algorithm applicable to generalized sidelobe canceller(GSC) based monopulse radar. We show that clutter estimation can be achieved via iterative process of the orthogonal projections. Through simulations, the proposed GSC-based system combined with the clutter estimation can outperform the conventional monopulse system in terms of target angle estimation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.2
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• pp.239-247
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• 2018

Adaptive Beamforming (ABF) algorithm, which is a typical jammer suppression algorithm, guarantees the performance on the assumption that the jamming characteristics of the TDS (Training Data Sample) are stationary, which are obtained immediately before and after transmitting the pulse signal. Therefore, effective jammer suppression can not be expected when the jamming characteristics are non-stationary. In this paper, we propose a new jammer suppression algorithm, of which power spectrum fluctuates fast. In this case, we assume that the location of the jammer station is fixed during the processing time. By applying the MPM (Matrix Pencil Method) to the jamming signal in TDS, we can estimate jammer parameters such as power and incident angle, of which the power will vary fast in time or range bins after TDS. Though we assume that the jammer station is fixed, the estimated jammer's incident angle has an error due to the noise, which degrades the performance of the jammer suppression as the jammer power increases fast. Therefore, the jammer's incident angle should be re-estimated at each range bin after TDS. By using the re-estimated jammer's incident angle, we can construct new covariance matrix under the non-stationary jamming environment. Then, the optimum weight for the jammer suppression is obtained by inversing matrix estimation method based on the matrix projection with the estimated jammer parameters as variables. To verify the performance of the proposed algorithm, the SINR (signal-to-interference plus noise ratio) loss of the proposed algorithm is compared with that of the conventional ABF algorithm.

• Journal of Navigation and Port Research
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• v.36 no.10
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• pp.833-838
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• 2012

TDOA which is one of the position estimation methods is used on indoor positioning, jammer localization, rescue of life, etc. due to high accuracy and simple structure. This paper proposes the super-resolution TDOA estimator using MPM(Matrix Pencil Method). The proposed estimator has more accuracy and is applicable to narrowband signal compared with the conventional cross-correlation. Furthermore, its complexity is low because obtained data directly is used for construction of matrix unlike the MUSIC(Multiple Signal Classification) which is one of the well-known super-resolution estimator using covariance matrix. To validate the performance of proposed estimator, errors of estimation and computational burden is compared to MUSIC through software simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.2164-2170
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• 2010

Digital Radio Frequency Memory, ( as DRFM ), is a device with the ability to restore output to the input RF signal in the required time after storing the incoming RF signals. Therefore DRFM is widely used in Jammer, EW Simulator, Target Echo Generator, and so on. This paper proposes its hardware implementation composed with the high frequency part and the digital processing part consisting of RF input/output module and local oscillator module. It is also proposed the replicated signal generation method which is consisted of the Analog-Digital conversion in the form of pulsed RF signal quantization, and FPGA to save and produce the playback signal, and RF signals to produce a Digital-Analog Conversion in the digital processing unit. This proposed scheme applied to test board and confirmed the validity of the proposed scheme through the test results obtained by the simulated input signals.