• Journal of Positioning, Navigation, and Timing
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• v.4 no.2
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• pp.57-65
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• 2015

Global Navigation Satellite System (GNSS) including Global Positioning System (GPS) is an important element for navigation of both the military and civil Unmanned Aerial Vehicle (UAV). Contrary to the military UAVs, the civil UAVs use the civil signals which are unencrypted, unauthenticated and predictable. Therefore if the civil signals are counterfeited, the civil UAV’s position can be manipulated and the appropriate movement of the civil UAV to the target point is not achieved. In this paper, spoofing on the autonomous navigation UAV is implemented through field experiments. Although the demanded conditions for appropriate spoofing attack exists, satisfying the conditions is restricted in real environments. So, the Way-point of the UAV is assumed to be known for experiments and assessments. Under the circumstances, GPS spoofing signal is generated based on the Software-based GNSS signal generator. The signal is emitted to the target UAV using the antenna of the spoofer and the effect of the signal is analyzed and evaluated. In conclusion, taking the UAV to the target point is hardly feasible. To implement the spoofing as expectation, the position and guidance system of the UAV has to be known. Additionally, the GPS receiver on the UAV could be checked whether it appropriately tracks the spoofing signal or not. However, the effect of the spoofing signal on the autonomous UAV has been verified and assessed through the experimental results. Spoofing signal affects the navigation system of the UAV so that the UAV goes off course or shows an abnormal operation.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.4
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• pp.165-172
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• 2016

A Global Navigation Satellite System (GNSS), which is typically exemplified by the Global Positioning System (GPS), employs a open signal structure so it is vulnerable to spoofing electronic attack using a similar malicious signal with that used in the GPS. It is necessary to require a spoofing test evaluation environment to check the risk of spoofing attack and evaluate the performance of a newly developed anti-spoofing technique against spoofing attacks. The present paper proposed a simulation method of spoofing environment based on simulator that can be implementable in a test room and analyzed the spoofing simulation performance using commercial GPS receivers. The implemented spoofing simulation system ran synchronized two GPS simulator modules in a single scenario to generate both of spoofing and GPS signals simultaneously. Because the signals are generated in radio frequency, a commercial GPS receiver can be tested using this system. Experimental test shows the availability of this system, and anti-spoofing performance of a commercial GPS receiver has been analyzed.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.3
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• pp.127-138
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• 2018

Spoofing attacks including meaconing can provide a bogus position to a victim GPS receiver, and those attacks are notably difficult to detect at the point of view on the receiver. Several countermeasure techniques have been studied to detect, classify, and cancel the spoofing signals. Based on the countermeasure techniques, we have developed an anti-spoofing equipment that detects and mitigates or eliminates the spoofing signal based on raw measurements. Although many anti-spoofing techniques have been studied in the literatures, the evaluation test system is not deeply studied to evaluate the anti-spoofing equipment, which includes detection, mitigation, and elimination of spoofing signals. Each study only has a specific test method to verify its anti-spoofing technique. In this paper, we propose the performance evaluation test system that includes both spoofing signal injection system and its injection scenario with the constraints of stand-alone anti-spoofing techniques. The spoofing signal injection scenario is designed to drive a victim GPS receiver that moves to a designed position, where the mitigation and elimination based anti-spoofing algorithms can be successively evaluated. We evaluate the developed anti-spoofing equipment and a commercial GPS receiver using our proposed performance evaluation test system. Although the commercial one is affected by the test system and moves to the designed position, the anti-spoofing equipment mitigates and eliminates the injected spoofing signals as planned. We evaluate the performance of anti-spoofing equipment on the position error of the circular error probability, while injecting spoofing signals.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.3
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• pp.283-289
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• 2015

In this paper, a GNSS interference detection algorithm based on an adaptive fading Kalman filter is proposed to detect a spoofing signal which is one of the threatening GNSS intentional interferences. To detect and mitigate the spoofing signal, the fading factor of the filter is used as a detection parameter. For simulation, the effect of the spoofing signal is modeled by the ramp type bias error of the pseudorange to emulate a smart spoofer and the change of the fading factor value according to ramp type bias error is quantitatively analyzed. In addition, the detection threshold is established to detect the spoofing signal by analyzing the change of the error covariance and the effect of spoofing is mitigated by controlling the Kalman gain of the filter. To verify the performance analysis of the proposed algorithm, various simulations are implemented. Through the results of simulations, we confirmed that the proposed algorithm works well.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.2
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• pp.101-111
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• 2023

Many spoofing detection studies have been conducted to cope with the most difficult types of deception among various disturbances of GPS, such as jamming, spoofing, and meaconing. In this paper, we propose a spoofing detection scheme based on elevation masked-relative received power between GPS L1 and L2 signals in a system using a multi-band array antenna. The proposed scheme focuses on enabling spoofing to be normally detected and minimizes the possibility of false detection in an environment where false alarms may occur due to pattern distortion among elements of an array antenna. The pattern distortion weakens the GPS signal strength at low elevation. It becomes confusing to detect a spoofing signal based on the relative power difference between GPS L1 and L2, especially when GPS L2 has weak signal strength. We propose design parameters for the relative power threshold including beamforming gain, the minimum received power difference between L1 and L2, and the patch antenna gain difference between L1 and L2. In addition, in order to eliminate the weak signal strength of GPS L2 in the spoofing detection process, we propose a rotation matrix that sets the elevation mask based on platform coordinates. Array antennas generally do not have high usefulness in commercial areas where receivers are operated alone, but are considered essential in military areas where GPS receivers are used together with signal processing for beamforming in the direction of GPS satellites. Through laboratory and live sky tests using the device under test, the proposed scheme with an elevation mask detects spoofing signals well and reduces the probability of false detection relative to that without the elevation mask.

• Journal of Advanced Navigation Technology
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• v.20 no.5
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• pp.394-400
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• 2016

It is well known that the encrypted ranging signal, such as GPS P(Y) code, is immune to spoofing attack. However, in order for users to use the signal, there needs permission from the operator. And also there are many restrictions for use because of security issues. In this paper, a ground reference station equipped with high-gain directional antenna and a user receiver were simulated. In the reference station, the encrypted code can be demodulated from the high-gain signal. And then the code can be used to detect spoofing attack in the user receiver. This paper proposes the spoofing detection method using the encrypted signal and deals with simulation results.

• Journal of Advanced Navigation Technology
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• v.17 no.2
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• pp.157-164
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• 2013

In the presence of spoofing signal the GPS signal having the same PRN with the spoofer is hard to be acquired since the power of spoofing signal is usually stronger than that of GPS signal. If a spoofing signal exists for the same PRN, there are double peaks in two-dimensional space of frequency and code phase in acquisition stage. Using double peak information it is possible to detect spoofing signal and acquire GPS information through separate channel tracking. In this paper we introduce an anti-spoofing method using double peak detection, and thus can acquire GPS navigation data after two-channel tracking for the same PRN as the spoofing signal.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.9
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• pp.1273-1280
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• 2014

This paper considers a GPS anti-spoofing problem. Spoofing is an intentional interference that mislead the GNSS receiver. The spoofing attack is very significant since the target receiver is not aware of being attacked from spoofing. Accelerometers can be used to detect the spoofing signal by being compared with the acceleration obtained from GPS information using Kalman filter. In this paper we propose an N by N-point average and M-point window algorithm to detect GPS spoofing by using accelerometers and GPS outputs. The performance of the proposed algorithm is analyzed using actual vehicle trajectory and spoofing trajectory generated from INS and GPS toolbox for simulation.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.2
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• pp.296-303
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• 2010

The term "spoofing" refers to the transmission of counterfeit signals to provide undetectable falsification of GPS service. A spoofing can be accomplished using information from open literature which defines the signal format and the data structure. Spoofing is intended either to produce erroneous navigation solutions or saturate the processor of the victim receiver. The GPS receiver has no way to get rid of the effect of a spoofing because GPS receivers for civil service do not have an anti-spoofing scheme. This paper analyzes the spoofing characteristics, spoofing methods and environment conditions. And the spoofing effects on GPS receiver are analyzed in detail using the designed software-based spoofer and the Nordnav receiver.

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