• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.136-140
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• 2015

In this paper, a comparative studies on the STAP and SFAP were performed, which are known as representative anti-jamming technology for adaptive array antenna. As a method of estimating the weighting vector for simulation, MMSE(Minimum Mean Square Error) algorithm was commonly used and the analyses of the simulation performance in various jamming environments were presented. Especially, performance comparison between STAP and SFAP according to the jamming power J/S(Jamming to Signal Power Ratio), performance comparison in the ratio of jamming bandwidth to signal bandwidth, and performance comparison of BER between STAP and SFAP were presented.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.2
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• pp.152-157
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• 2013

In this paper, we represent the implementation and performance analysis of vector tracking loop based GPS receiver for jamming environment. The vector tracking loop navigation performance is compared by simulation with conventional tracking loop. The simulation results shows that vector tracking loop is more robust than conventional tracking loop in jamming environment. The vector tracking loop can gain 2dB in jamming performance capability over a conventional GPS receiver. Also, Anti-jamming performance of INS Doppler aiding and deep integration method are compared.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.10
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• pp.2883-2902
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• 2023

Since the existing anti-jamming methods, including intelligent methods, have difficulty against high-speed reactive jamming, we studied a new methodology for jamming utilization instead of avoiding jamming. Different from the existing jamming utilization techniques that harvest energy from the jamming signal as a power supply, our proposed method can take the jamming signal as a favorable factor for frequency detection. Specifically, we design an intelligent differential frequency hopping communication framework (IDFH), which contains two stages of training and communication. We first adopt supervised learning to get the jamming rule during the training stage when the synchronizing sequence is sent. And then, we utilize the jamming rule to improve the frequency detection during the communication stage when the real payload is sent. Simulation results show that the proposed method successfully combated high-speed reactive jamming with different parameters. And the communication performance increases as the power of the jamming signal increase, hence the jamming signal can help users communicate in a low signal-to-noise ratio (SNR) environment.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.1
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• pp.115-123
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• 2018

In this paper, we consider the applicability of time-hopping(TH) systems for anti-jamming(AJ) communication. We first briefly summarize fundamentals of TH systems and several common jamming scenarios that have been considered in the literature. We then analyze the AJ performance of TH systems under those common jamming environments. From our simulation results, we reveal that among narrow band, partial band, broadband, and sweep jamming, partial band and sweep jamming are the best ones from jammer perspective. For the partial band jamming case, we show that the most effective bandwidth ratio and location are 50 % and 2.5-3.5 Ghz, respectively. For the sweep jamming case, we illustrate that the AJ performance of the TH system is enhanced when the sweep duration approaches to the bit duration. In addition, we pointed out that the most efficient jamming bandwidth ratio is 1/2. Finally, our results show that the TH-BPSK system greatly outperforms the TH-PPM counterpart.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.2
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• pp.51-57
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• 2020

For the purpose of development of anti-jamming GPS receiver we have developed an anti-jamming algorithm and its Simulink implementation model. The algorithm used here is a form of Space-Time Adaptive Processing (STAP) filter which is well known as an effective way to remove wideband jamming signals. We have chosen Minimum Variance Distortionless Response (MVDR) block-adaptive beamforming algorithm for our development since it can provide relatively fast convergence speed to reach optimal weights, stable and high suppression capability on various types of jamming signals. We will show modeling results for this MVDR type adaptive beamformer and some simulation results. We also show the integrity of the demodulated satellite signals and the accuracy of resulting navigation solutions after anti-jamming operation.

• ETRI Journal
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• v.42 no.1
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• pp.138-149
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• 2020

In this paper, we describe a simultaneously transmitted jamming (ST-jamming) for bi-directional in-band full-duplex (IFD) system to improve information security at the physical layer. By exploiting ST-jamming, each legitimate user transmits data samples and jamming samples together in one orthogonal frequency division multiplexing symbol according to given traffic asymmetry. Regardless of the traffic difference in both directions in IFD communication, eavesdropping of confidential information is prevented in both directions simultaneously without the loss of data rate. We first propose an encoding scheme and the corresponding decoding scheme for ST-jamming to be used by the legitimate users. In addition, we study a transceiver structure of the legitimate users including a baseband modem uniquely designed for the use of ST-jamming. The leakage of confidential information at an eavesdropper is then quantified by studying the mutual information between the confidential transmit signals and the received signals of the eavesdropper. Simulation results show that the proposed ST-jamming significantly reduces the leakage of legitimate information at the eavesdropper.

• Journal of Positioning, Navigation, and Timing
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• v.3 no.2
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• pp.45-51
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• 2014

GNSS has the disadvantage of being vulnerable to jamming, and thus, the necessity of jamming countermeasure techniques has gradually increased. Jamming countermeasure techniques can be divided into an anti-jamming technique and a jammer localization technique. Depending on the type of a jammer, applicable techniques and performance vary significantly. Using an appropriate jamming countermeasure technique, the effect of jamming on a GNSS receiver can be attenuated, and prompt action is enabled when estimating the location of a jammer. However, if an inappropriate jamming countermeasure technique is used, a GNSS receiver may not operate in the worst case. Therefore, jammer identification is a technique that is essential for proper action. In this study, a technique that identifies a jammer based on template matching was proposed. For template matching, analysis of a received jamming signal is required; and the signal analysis was performed using a spectral correlation function. Based on a simulation, it was shown that the proposed identification of jamming signals was possible at various JNR.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.3
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• pp.221-228
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• 2020

This paper presents the radar counter jamming algorithm and ground far-field test results for the pull-off deceptive jamming signals like RGPO(Range Gate Pull Off) and VGPO(Velocity Gate Pull Off). We designed the radar counter jamming algorithm according to the characteristics of the deceptive jamming signals. This algorithm is validated by simulation before ground far-field test. The existing X-band AESA radar demonstrator was used to test the proposed algorithm. The proposed algorithm was applied to the radar processor software. The deceptive jamming signals generated using the commercial jamming signal generator. We performed the repeated ground far-field test with the test scenario. Test results show that the proposed counter deceptive jamming algorithm works in the real radar system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.9
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• pp.3444-3457
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• 2021

In the field of anti-jamming based on dynamic spectrum, most methods try to improve the ability to avoid jamming and seldom consider whether the jammer would perceive the user's signal. Although these existing methods work in some anti-jamming scenarios, their long-term performance may be depressed when intelligent jammers can learn user's waveform or decision information from user's historical activities. Hence, we proposed a hidden anti-jamming method to address this problem by reducing the jammer's sense probability. In the proposed method, the action correlation between the user and the jammer is used to evaluate the hiding effect of the user's actions. And a deep reinforcement learning framework, including specific action correlation calculation and iteration learning algorithm, is designed to maximize the hiding and communication performance of the user synchronously. The simulation result shows that the algorithm proposed reduces the jammer's sense probability significantly and improves the user's anti-jamming performance slightly compared to the existing algorithms based on jamming avoidance.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.6
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• pp.776-784
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• 2009

The function of DIRCM(Directed Infrared Countermeasures) jamming is to cause the missile to miss its intended target by disturbing the seeker tracking process. The DIRCM jamming uses the pulsing flashes of IR energy and its frequency, phase and intensity have influence on the missile guidance system. In this paper, we analysis the DIRCM jamming effect of spin-scan reticle seeker. Simulation results show that the jamming effect is greatly influenced by frequency, phase and intensity of the jammer signal.