With the increasing application demands for radar jammers, traditional array designs and direction-finding algorithms exhibit critical limitations: excessive information redundancy in uniform arrays, restricted estimation accuracy due to limited physical aperture, and significant performance degradation when processing coherent signals. To address these issues, this paper proposes a coherent signal Direction of Arrival (DOA) estimation method based on spatial smoothing preprocessing and the MUSIC algorithm, integrated with a two-dimensional composite uniform arrays. The method aims to overcome traditional array design constraints and mitigate DOA performance deterioration caused by coherent signals. Specifically, the spatial smoothing technique leverages the translational invariance property of uniform arrays to effectively solve the rank deficiency in covariance matrices induced by coherent signals. The two-dimensional composite uniform array adopts a sparse array configuration to expand the effective aperture under the same number of array elements, thereby enhancing DOA resolution. Experimental validation combines two-dimensional spatial smoothing with the MUSIC algorithm for DOA estimation of coherent signals on the composite array. Results demonstrate that the spatial smoothing method successfully suppresses coherent signal interference, while the composite array achieves superior DOA estimation performance compared to traditional uniform arrays with identical element counts, validating the effectiveness of the proposed methodology.

With the rapid development of smart vehicles and autonomous driving technology, high-precision 3D navigation has emerged as a crucial supporting technology. However, the limitations of the BeiDou Navigation Satellite System (BDS) in terms of accurate elevation positioning and complex, variable highway traffic scenarios have posed constraints on autonomous and intelligent driving systems. This paper proposes a BDS+5G integrated positioning model based on adaptive Kalman filtering technology, aiming to address the decline in positioning accuracy caused by signal occlusion, signal loss, and multipath effects in complex highway traffic environments. By constructing an integrated positioning vector equation and introducing innovation vectors and robust factors, the model achieves adaptive suppression of measurement noise, thereby enhancing positioning accuracy. Field tests conducted at the Liuxia Hub on the Hangzhou Beltway Expressway, coupled with superimposed validation using 3D high-precision laser point cloud maps, demonstrate that this model can significantly improve positioning performance in complex traffic environments, with an elevation positioning error of less than 0.2 m, capable of supporting 3D lane-level navigation. This validates the application potential of BDS+5G hybrid positioning technology in the field of smart vehicles and autonomous driving.

In order to improve the orbit determination accuracy of BDS satellites and solve the problem of limited construction of BDS ground stations, this paper proposes a solution using a LEO constellation as a space-based monitoring station. Two indicators were proposed to evaluate the monitoring performance of LEO constellations: Monitoring coverage factor and Satellite Position Dilution of Precision(SPDOP), and different configuration parameters of LEO constellations were optimized, including orbital altitude, number of orbital planes, orbital inclination angle, and number of satellites. An optimal LEO constellation was designed using the BDS-3 satellite as the monitoring object, and the monitoring capability of the LEO constellation was verified based on 30 tracking stations of the iGMAS system. The results show that the monitoring performance of the designed LEO constellation is superior to that of the iGMAS system with 30 tracking stations. The LEO constellation can achieve at least 6-fold of coverage over the entire arc of the BDS satellite with the minimum number of LEO satellites, with a good and stable geometric layout, which helps to improve the orbit determination accuracy of the BDS system and provide high-quality observation data for monitoring and evaluating the operating status and service performance of the BDS system.

Considering the wide application and critical importance of satellite navigation systems, aiming at the requirements for precision and reliability of the next-generation BeiDou satellite navigation system, this study investigates the current development status of integrity technology from four dimensions: basic integrity of satellite navigation systems, integrity of satellite-based augmentation systems (SBAS), advanced receiver autonomous integrity monitoring (ARAIM), and precise point positioning (PPP)integrity, and compares the technical difficulties of each. Finally, it explores the development trends of future integrity technologies. This study is significant for the design and construction of the integrity system of the next-generation BeiDou satellite navigation system.

To meet the demand for highly efficient folding and high gain antenna used in CubeSats, a deployable reflector antenna that can be tightly coiled was presented using flexible composite materials. The antenna was mainly composed of flexible reflector, cylindrical shell boom, sub-reflector and feed. The cylindrical shell booms play the role to deploy and maintaining the flexible reflector in the needed shape. One end of each cylindrical shell boom was connected to the periphery of the reflector, while the other one was fixed to the center of the antenna. A simple method was developed to predict the coiling load using elastic Euler beam theory. A 0.5 m prototype antenna was constructed and tested for coiling deployment and RF performance. The diameter and height of the prototype in coiled state were nearly 140 mm and 180 mm separately, and the predicted constraint load was 24% higher than the test value.

To evaluate the Doppler positioning performance of Low Earth Orbit (LEO) satellites, this paper analyzes the related errors and positioning performance of single-LEO navigation test satellite. Furthermore, the worldwide constellation Doppler positioning performance is analyzed in conjunction with low-orbit constellation simulation extrapolations. The results show that: ① The Doppler measurement error accuracy is at the decimetre level, which is more than one order of magnitude greater than the other error terms. Furthermore, the Doppler User Equivalent Range Rate Error (UERRE) accuracy of the comprehensive related error term is better than 0.27 m/s; ② The single-satellite Doppler positioning 3D error converges to 200 m in approximately eight minutes, with a post-convergence positioning accuracy of approximately 85 m. Furthermore, the single-star Doppler-equivalent PDOP eventually converges to around 200; ③ When the cut-off altitude angle is 10° or less and the cumulative observation time is 8 min or more, the global average of the constellation Doppler equivalent PDOP is superior to 28.8 m, the RMS is superior to 58.8 m, and better than 156.1 m on the 95%. Furthermore, the constellation Doppler positional accuracy (3D, 1σ) is superior to 7.8 m on average globally, and better than 15.9 m on the RMS, and better than 42.2 m on the 95%. The constellation Doppler-equivalent PDOP and positional accuracy are optimal at high latitudes, suboptimal at midlatitudes, and relatively poor at low latitudes.

Traditional inertial-satellite integrated navigation relies on satellite navigation to provide high-precision positioning results for position correction, which is difficult to adapt to the environment of strong suppression interference. To address this issue, this paper proposes an inertial navigation correction method based on interference direction-of-arrival (DOA) estimation, which can provide satellite-independent positioning correction information in strong jamming environments. The algorithm first estimates the interference direction-of-arrival (DOA) using compressed sensing-based direction finding, then combines this with the shortterm high-precision vehicle trajectory provided by inertial navigation to localize low-dynamic or stationary interference sources. Subsequently, it utilizes the estimated interference source positions and DOA information to inversely determine the aircraft’s position, ultimately providing the inertial navigation system with a satellite-independent correction reference. It is suitable for extreme suppression interference confrontation environment where satellite navigation cannot work for a long time. The main innovation is that a robust positioning method based on the position estimation of the interference source, which provides a extra positioning information source other than satellite navigation for inertial navigation in the application scenario where satellite navigation fails due to interference, and the corrected positioning information source does not need to add additional hardware sensors. The simulation results show that the algorithm can provide stable positioning for inertial navigation in the environment of four static strongly suppressed interference sources, and meet the navigation and positioning requirements in the environment of strong electromagnetic interference.

With the rapid development of satellite communication technology, the volume of data transmitted between satellites and ground stations continues to increase, driving higher demands for signal transmission rates and quality. In traditional modulators, due to limitations such as DAC(Digital-to-Analog Converter)sampling rates and shaping filter technologies, low-order modulation is often adopted, resulting in lower signal transmission rates that cannot meet the requirements of future high-speed transmission. Therefore, a 16-channel parallel shaping filter technology with a continuously variable transmission rate is proposed in this paper. This technology employs 64APSK(Amplitude Phase Shift Keying)modulation to achieve high-speed data transmission. Experimental results show that, based on the existing hardware platform, data transmission at a rate of 7.2 Gbps is achieved with a 4.8 GHz DAC sampling rate, and the EVM (Error Vector Magnitude)is as low as 2.029 9%. Compared to the original high-speed modulator architecture, this technology offers advantages such as high transmission rates, good signal quality, and low resource consumption, making it a valuable reference for the design of future systems for data transmission exceeding 10 Gbps.

In the guidance and control of the first-stage recovery of rocket, the carrier pose measurement is very important. Inertial navigation, satellite navigation, LiDAR are usually used to measure the pose in engineering, while there is no precedent for visual measurement. Visual measurement has the advantages of no cumulative error and high update rate, and has the potential to be applied to rocket recovery. In this paper, the dynamics model of rocket recovery is analyzed and trajectory simulation is carried out, and the Falcon9 rocket is taken as the simulation object and the optimal trajectory is obtained by a convex optimization method. Four cameras were installed in the first stage of the rocket, and the visual pose measurement was realized through the multi-vision sensor measurement model, image target recognition and feature picking. The calculation results show that the visual measurement technology proposed in this paper has a high position accuracy and has the prospect of engineering application.

To address the issue of the baffle of antenna cover baffle obstructing signal transmission and receiving of vehicle ground station under low-elevation condition. Firstly, the solution of the foldable mechanism was identified and the bidirectional spring coaxial parallel system which defined the key technology was studied. Secondly, start with the movement process of the folding mechanism, the mathematical model of total system was established, the influencing factors of spring damping deformation and their analytical values were obtained. Then, the dynamic analysis of the spring coaxial parallel system was carried out, and the dynamic parameters of the system were obtained. The obtained three groups parameters were combined with the virtual prototype for dynamic simulation, and through the analysis of the torsional moment curves under the separate action of the inter and outer springs and their joint action. The results showed that the proposed bidirectional spring coaxial parallel system acted alone compared with the inter and outer springs. The value of dynamic peak not only attenuated significantly(approximately 75 %~90 %)but also the dynamic peak frequency was significantly reduced, which verified that the structure with inter and outer springs connected in coaxial parallel had more stable dynamic characteristics, and which provided the favorable reference for other similar engineering projects.