## 1 Introduction
However, this technique requires massive computational resources and remains incapable of determining the exact positions of spoofing signal sources. Existing spatial information processing techniques can be categorised mainly into three types: mobile single-antenna, dual-antenna array, and multi-antenna array. The mobile single-antenna technique detects spoofing in basic static scenarios based on Doppler information and single-differenced carrier-phase information; however, there are limitations in identifying the directions of the signal sources. [PERSON] et al. employed two fixed antennas to form a baseline vector and ascertain the similarity of carrier-phase data to achieve spoofing detection [18]. However, this model is unable to effectively determine the direction of arrival (DOA) of a signal source and cannot provide direction indication for countermeasures such as zeroing antennas. This study aims to independently determine the DOA of a navigation signal from a single satellite through integrated navigation based on the inter-station single-difference carrier-phase information received by the common-clock dual antennas and the information provided by a micro-inertial measurement unit (MIMU). The direction of the signal source is determined by constructing a dual-antenna inter-station single-difference carrier-phase observation model and utilising the multi-epoch data of the carrier in the dynamic motion state. The proposed method effectively addresses the challenges faced by small vehicles equipped with dual GNSS antennas in identifying spoofed signals and determining the directions of signal sources. Based on the background mentioned earlier, this paper proposes a method for determining the directions of the deceptive signal source in the dynamic carrier coordinate system based on the dual-antenna carrier phase observations and inertial measurements with multiple epochs. A new method is proposed to determine the single-differenced integer ambiguity between two GNSS antenna with short baseline which is combined with the dual-GNSS antenna/MIMU integration information to determine the two-dimensional directions of the spoofing interference source. This method utilises the broadcasted satellite ephemeris and MEMS-based inertial navigation to forecast the direction of satellite navigation signals. By analysing the anomalies between the direction of the spoofing signal source and the forecasted direction from the ephemeris information, effective identification of the spoofing signals can be achieved. Due to insufficient observation information from a single epoch, this paper proposes a trajectory planning strategy that involves significant manoeuvring in at least one direction over multiple epochs. A multi-epoch observation model is established based on the changes in the attitude and carrier-phase observations along the trajectory, thereby providing high-accuracy two-dimensional direction information for the spoofing signal source. Furthermore, this paper establishes a real-time two-dimensional direction determination model for extended Kalman Filter (EKF) filtering. This study assesses the effectiveness and accuracy of the proposed method through both simulation and experimental tests. The structure of the paper is presented as follows. Section 2 briefly introduces the system models of the proposed method, including the integrated system model, the satellite signal observation model, and two-dimensional direction model for spoofer. Section 3 derives a new method for single-frequency single-epoch dual-frequency station single-difference ambiguity resolution, and establishes the two-dimensional direction determination method for spoofing signal sources. Section 4 verifies the effectiveness of the proposed method through a comprehensive simulation analysis and a land vehicular test. Section 5 concludes this paper.