• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2021.10a
• /
• pp.664-666
• /
• 2021

Anti-drone means a device that detects and blocks the intrusion and activity of illegal drones, and includes technology that crashes illegal drones or destroys them in the air. This paper analyzes the impact of jamming due to remote drone detection with anti-drone technology. The impact of jamming signals may vary depending on the distance of the drone. The present invention has an advantage of simultaneously jamming a drone at a short distance and a drone at a long distance due to the generation of a triangular wave, and efficiently operates a battery by not transmitting the drone at a maximum power.Also, even if the jamming is not affected at a distance, the jamming effect is greater at a close range, so it can be influenced differently.

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

• Journal of Digital Convergence
• /
• v.11 no.12
• /
• pp.417-422
• /
• 2013

In this paper, the implementation of a null-steering antenna array using GPS patch antennas is suggested. The antenna array consists of five patch antenna elements fabricated on the ceramic substrate. The antenna element proposed here is a typical circular polarization patch and a prototype patch array antenna is manufactured on the PCB. The antenna has one reference element located at the center and other four elements are placed at the corners. A null in the direction of the jamming signal can be produced by changing the phases of 4-elements. Simulation results of the array antenna by CST MWS are presented and discussed. The basic performances are measured and the results are shown. The results show that the antenna presented here can be used to remove the signals from the directions of any jammers.

• Journal of Positioning, Navigation, and Timing
• /
• v.9 no.2
• /
• pp.125-129
• /
• 2020

In this paper, Zero velocity UPdaTe (ZUPT) is implemented on the navigation system of Remotely Piloted Aircraft for GNSS denied environment. RPA's navigation system suffers from lack or loss of satellite signal while maintenance or ground test inside a hangar. Although some of the hangars install GPS repeaters for indoor tests, the anti-jamming equipment with array antenna blocks the repeater signal regarding them as hostile jamming signal. With ZUPT, an aircraft navigation system can be tested free from the divergence of navigation solution without line-of-sight satellites. The designed ZUPT aided centralized Kalman Filter is implemented on the Embedded GPS&INS and simulated with Captive Flight Test data. The simulation result shows stable navigation solution without GNSS updates.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38A no.9
• /
• pp.792-797
• /
• 2013

This paper has derived the conversion loss according to the synchronized condition between the transmitted and locally generated spreading signals for the civil global positioning system (GPS) receiver in the heavy wideband Gaussian noise environments. From this, the outputs of the 2-bit nonuniform quantizer, which has the minimum conversion loss, is set to ${\pm}1$ and ${\pm}2$, while the quantization step size is approximated to the jamming-to-signal power ratio.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39C no.11
• /
• pp.1023-1030
• /
• 2014

Beam steering algorithms using array antenna are mainly used in such a manner as anti-jamming method. However, the performance is changed according to the position of signals despite the same number of signals and the same received power. In this paper, we analyzed the effect of the position relationship of the signals on the performance of the beam steering algorithms. Therefore, we defined 'signal separation' as the minimum angle of the interference signals and the desired signal, and analysed the relationship between the C/N0 performance of beam steering algorithms as LCMV/PM and the signal separation. For simulation, we set many GPS signals and jamming signals compared to the degrees of freedom. And changed the position and the height of the receiver in order to obtain various signal separation angles. In addition, we examined the effects of signal separation and JSR on the anti-jamming performance by applying the loss factors of the received power. Through the research, there is a tendency that the performance of beam steering algorithms is increased with the increase of the signal separation, and signal separation is more severely affecting on the anti-jamming performance compared to the number of signals and JSR.

• Journal of Positioning, Navigation, and Timing
• /
• v.3 no.2
• /
• pp.37-44
• /
• 2014

The most effective method to overcome GPS jamming problem is to use an adaptive array antenna which has the capability of beamforming or nulling to a certain direction. In this paper, Space Time Adaptive Processing (STAP) beamforming algorithm of four elements array antenna will be designed and the anti-jamming performance will be analyzed. According to the analysis, the signal to noise ratio (SNR) and anti-jamming performance can be enhanced by beamforming algorithm. Also, the time tap effect of STAP algorithm will be analyzed theoretically and verified with array antenna modeling and simulation. Specially, the cautious selection of reference time tap in STAP can prevent the degradation of position accuracy performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.12
• /
• pp.1112-1115
• /
• 2016

Global Positioning System(GPS) is a useful system used in both civilian and military applications. However, the signal of GPS is susceptible to jamming attacks due to low receive sensitivity, since the signals come from the satellite located at over 20,000 km above the earth. In this paper, we have conducted a preceding research on a non-Foster matching circuit that efficiently matches an electrically ultra-small GPS antenna. Electrically Small Antennas(ESAs) are inefficient radiators and are difficult to match in wideband due to extremely high quality factor. In order to match small GPS antenna in wideband, a non-Foster matching circuit for a small GPS antenna was designed. A negative impedance converter circuit consisting of Linvill's cross-coupled pair transistors was fabricated and its stability was verified by the time-domain stability analysis. In addition, anechoic chamber measurements show that the non-Foster matching circuit for small GPS antenna can lead bore-sight gain improvement by more than 17 dB.

• Journal of Positioning, Navigation, and Timing
• /
• v.5 no.3
• /
• pp.131-136
• /
• 2016

The present paper shows that beamforming algorithm such as Minimum Variance Distortionless Response (MVDR) based on array antenna signal processing can have not only anti-jamming but also anti-spoofing characteristics. A beam pattern due to the beamforming algorithm strengthens received signal power as it is formed in the incident direction of desired signal. During the process, the effect of unnecessary signals such as spoofing signals can be reduced because the beam pattern reduces received signal power in the incident directions excluding the beam pattern-directed direction. In order to analyze the anti-spoofing effect due to the beamforming algorithm, a software-based simulation environment was configured. An arbitrary error was applied between incident direction of Global Positioning System (GPS) satellite signal and steering vector direction of the beamforming algorithm to analyze the received signal power and required conditions were provided to see the anti-spoofing effect due to the beamforming algorithm. The used antenna was 7-element planar circular array and beam patterns were formed through the MVDR algorithm.

• Journal of Positioning, Navigation, and Timing
• /
• v.11 no.2
• /
• pp.127-134
• /
• 2022

In this paper, a low-cost, flexible GPS simulator based on USRP is designed as a general-purpose software wireless front-end. The simulator consists of a software GPS signal generator and a USRP-based RF transmitter. The simulator supports various scenarios including specified reception time, quantization bit level, I/Q data types, IF frequency, sampling frequency, SNR, ionospheric delay and user dynamics. The generated GPS RF signal is verified using the spectrum analyzer and off-the-shelf GNSS receivers such as U-blox M8T. The experimental results shows that the difference between generated and real live signal is ignorable. It is expected that designed GPS simulator can be used to GNSS signal design, receiver design and signal processing algorithms such as anti-jamming.