A covert spoofing algorithm of an unmanned aerial vehicle (UAV) based on GPS/INS integrated navigation is analyzed in this paper. The proposed algorithm theoretically proves the fact that: when the acceleration component of the counterfeit GPS signal is the difference between the UAV's current acceleration and the spoofing control input, the UAV can be covert spoofed. To avoid adverse consequences (detection or crash) caused by frequent changes in UAV flight during the GPS spoofing attacks, the proposed algorithm requires that the deception trajectory planned by the GPS spoofer is slowly changing relative to the reference trajectory which is pre-set by the UAV. Simulation results have verified the correctness of the proposed covert spoofing algorithm of UAV. Moreover, the spoofing effect is more distinct when the deception trajectory planning is considered.

Since the drifts of Inertial Navigation System (INS) solutions are inevitable and also grow over time, a Doppler Velocity Log (DVL) is used to aid the INS to restrain its error growth. Therefore, INS/DVL integration is a common approach for Autonomous Underwater Vehicle (AUV) navigation. The parameters including the scale factor of DVL and misalignments between INS and DVL are key factors which limit the accuracy of the INS/DVL integration. In this paper, a novel parameter calibration method is proposed. An iterative implementation of the method is designed to reduce the error caused by INS initial alignment. Furthermore, a simplified INS/DVL integration scheme is employed. The proposed method is evaluated with both river trial and sea trial data sets. Using 0.03°/h(1σ) ring laser gyroscopes, 5 × 10⁻⁵ g(1σ) quartz accelerometers and DVL with accuracy 0.5% V ± 0.5 cm/s, INS/DVL integrated navigation can reach an accuracy of about 1‰ of distance travelled (CEP) in a river trial and 2‰ of distance travelled (CEP) in a sea trial.

Gyroscopes based on micro-electromechanical system (MEMS) technology suffer in high-dynamic applications due to obvious g-sensitivity errors. These errors can induce large biases in the gyroscope, which can directly affect the accuracy of attitude estimation in the integration of the inertial navigation system (INS) and the Global Positioning System (GPS). The observability determines the existence of solutions for compensating them. In this paper, we investigate the observability of the INS/GPS system with consideration of the g-sensitivity errors. In terms of two types of g-sensitivity coefficients matrix, we add them as estimated states to the Kalman filter and analyze the observability of three or nine elements of the coefficient matrix respectively. A global observable condition of the system is presented and validated. Experimental results indicate that all the estimated states, which include position, velocity, attitude, gyro and accelerometer bias, and g-sensitivity coefficients, could be made observable by maneuvering based on the conditions. Compared with the integration system without compensation for the g-sensitivity errors, the attitude accuracy is raised obviously.

Intentional spoofing interference can cause damage to the navigation terminal and threaten the security of a global navigation satellite system (GNSS). For spoofing interference, an anti-spoofing algorithm based on pseudorange differences for a single receiver is proposed, which can be used to detect simplistic and intermediate spoofing attacks, as well as meaconing attacks. Double-difference models using the pseudorange of two adjacent epochs are established followed by the application of Taylor expansion to the position relationship between the satellite and the receiver (or the spoofer). The authenticity of the signal can be verified by comparing the results of the proposed spoofing detection algorithm with the traditional least squares method. The results will differ when spoofing is present. The parameter setting of the proposed algorithm is introduced. The algorithm has the advantage of both simplicity and efficiency and needs only a single receiver and pseudorange data. A NovAtel receiver is adopted for the actual experiments. The Texas spoofing test battery (TEXBAT), as well as two other simulation experiments are used to verify the performance of the algorithm. The simulation results validate the feasibility and effectiveness of the algorithm.

To meet the task requirements of using GNSS spoofing signals to achieve directional spoofing of unmanned target platforms, this paper proposes an INS/GNSS integrated navigation covert directional spoofing method, which can be used in key place security defense and public security protection scenarios. Taking the steady-state gain matrix as a breakthrough, this paper firstly studies the influence mechanism of GNSS spoofing signals on the position output of INS/GNSS integrated navigation, and then deduces the feasibility of directional spoofing by using exponential spoofing signal with two adjustable parameters in INS/GNSS integrated navigation mode. Then, the influence of spoofing signals on the attitude and speed of the integrated navigation output is analyzed, and the relevant constraints of velocity and attitude errors are introduced to determine the exponential GNSS spoofing signals model that meets the requirements of covertness, and finally the task of covert directional spoofing of the target unmanned platform is realized. Simulation and experiments verify the effectiveness and correctness of INS/GNSS covert directional spoofing method.

In order to solve the spoofing problem of SINS/GNSS tightly integrated navigation system with inertial assist spoofing detection module, this paper proposes a covert spoofing algorithm for SINS/GNSS tightly integrated navigation system. Firstly, the influence mechanism of the GNSS spoofing signal on the innovation and state estimation parameters of the SINS/GNSS tightly integrated navigation system is analyzed, and then the GNSS spoofing signal model is established with the constraint condition of the influence of the GNSS spoofing signal on the innovation and state estimation parameters of the SINS/GNSS tightly integrated navigation system. Secondly, the mathematical model of covert spoofing is constructed by using the GNSS spoofing signal model. Finally, SINS/GNSS tightly integrated navigation system is spoofed by GNSS spoofing signal generated according to the mathematical model of covert spoofing. Note to Practitioners —The motivation of this paper is to solve the spoofing problem of SINS/GNSS tightly integrated navigation system, so as to realize the control of the illegal unmanned platform equipped with tightly integrated navigation system. The existing spoofing methods are easily detected by the spoofing detection module, and it is difficult to meet the spoofing requirements of SINS/GNSS tightly integrated navigation system equipped with inertial aided spoofing detection module. This paper proposes a covert spoofing algorithm. Firstly, the influence mechanism of GNSS spoofing signal on SINS/GNSS tightly integrated navigation system is analyzed. Then, the mathematical model of covert spoofing is established by taking the influence of GNSS spoofing signal on the innovation parameter and state estimation parameters of SINS/GNSS tightly integrated navigation system as the constraint condition. Finally, the GNSS spoofing signal generated by the covert spoofing mathematical model is used to spoof the SINS/GNSS tightly integrated navigation system. Simulation and experimental results verify the effectiveness and correctness of the proposed method. In the future research, we will further promote the experiment and application of spoofing technology in the control of various illegal unmanned platforms.