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In the large-scale satellite constellation technology, the establishment of satellite internal network is the top priority. As the network capacity of the constellation continues to expand and the number of satellite nodes continues to increase, the previous multiple access technology can no longer meet the network capacity requirements of large-scale constellations. In order to meet the requirements of massive connections of satellite nodes in large-scale constellation for new networking communication methods, this paper establishes a sparse spread spectrum inter-satellite communication system with sparse code multiple access (SCMA) as the core. At the same time, the channel characteristics of large-scale constellation are analyzed and the corresponding inter satellite channel model is established in MATLAB. Based on this channel model, the performance of the system is simulated. The simulation results show that under the same signal energy to noise ratio, the sparse spread spectrum inter-satellite communication system established in this paper has better BER characteristics compared with orthogonal frequency division multiple access (OFDMA) and code division multiple access (CDMA). In addition, the threshold signal energy to noise ratio of the system is more than 2 dB better than that of CDMA technology, and the utilization rate of time-frequency resources is 50% higher than that of OFDMA technology.

Abstract A low‐complexity anti‐multipath interference spread spectrum communication system is proposed to address shortcomings in traditional anti‐multipath technology, such as complex structures and high resource consumption. The system utilizes a fast Fourier transform to capture pseudo‐noise code signals and simultaneously detect multipath signals. Moreover, the signal‐to‐noise ratio (SNR) of each path signal is calculated, and the multipath signal is synthesized through the designed optimal SNR synthesis method to improve the SNR of the demodulated signal to reduce the bit error rate. MATLAB is used to perform functional simulations of the system to verify its feasibility. The simulation results show that the system can successfully detect and synthesize multipath signals and achieve lower communication error rates than traditional code division multiple access (CDMA) systems.

Abstract Aiming at the problems of high system cost, complex ranging process, low ranging accuracy, and limited measurement distance in commonly used methods for ground fixed point distance measurement journals, a variable frequency microwave ranging system based on a dual transponder architecture is proposed in this letter. The system uses carrier dual transponder as an active forwarding architecture, utilizing the digital phase‐locked loop to obtain the high‐precision phase difference between two signals, and resolving the ambiguity through microwave frequency sweep within a certain range. The simulation results show that the system can quickly obtain the unambiguous distance between two fixed points, besides, driven by a high‐stability crystal oscillator, submillimetre accuracy can be achieved in km‐level ranging.

In recent years, the low Earth orbit microsatellite network technology has experienced rapid development due to its advantages of low latency, low cost, and short development cycles. However, building an efficient and reliable satellite network routing system faces many challenges due to the characteristics of satellite networks, such as fast‐changing topology, large variations in link latency, higher probabilities of node and link failures, and limited resources. Routing algorithms have a significant impact on intersatellite communication and have become a research hotspot. The current mainstream algorithms focus on reducing information propagation delays between satellites to enable faster transmission. However, many satellite networks, such as meteorological observation satellite networks, are not sensitive to propagation delays but emphasize reducing hardware costs, especially for the receiving and transmitting signal systems of satellites. This means minimizing the single‐step signal transmission distance of satellites. This article proposes a routing algorithm based on time slot planning and the shortest path step length. Experimental simulation results demonstrate that this algorithm significantly reduces the step length of signal transmission and lowers hardware costs. [ABSTRACT FROM AUTHOR]

This paper reports an approach of in-operation temperature bias drift compensation based on phase-based calibration for a stiffness-tunable MEMS accelerometer with double-sided parallel plate (DSPP) capacitors. The temperature drifts of the components of the accelerometer are characterized, and analytical models are built on the basis of the measured drift results. Results reveal that the temperature drift of the acceleration output bias is dominated by the sensitive mechanical stiffness. An out-of-bandwidth AC stimulus signal is introduced to excite the accelerometer, and the interference with the acceleration measurement is minimized. The demodulated phase of the excited response exhibits a monotonic relationship with the effective stiffness of the accelerometer. Through the proposed online compensation approach, the temperature drift of the effective stiffness can be detected by the demodulated phase and compensated in real time by adjusting the stiffness-tuning voltage of DSPP capacitors. The temperature drift coefficient (TDC) of the accelerometer is reduced from 0.54 to 0.29 mg/°C, and the Allan variance bias instability of about 2.8 μg is not adversely affected. Meanwhile, the pull-in resulting from the temperature drift of the effective stiffness can be prevented. TDC can be further reduced to 0.04 mg/°C through an additional offline calibration based on the demodulated carrier phase representing the temperature drift of the readout circuit.Highlights: The temperature drift behavior of a MEMS accelerometer with stiffness-tuning double-sided parallel-plate capacitors is investigated. An in-operation temperature drift compensation approach is proposed based on the extracted phase of an AC stimulus acceleration. The proposed stiffness-loop phase closed-loop can reduce the temperature drift of the proposed accelerometer while preventing the temperature drift-induced pull-in. [ABSTRACT FROM AUTHOR]

Space robots exhibit a strong dynamic coupling between the manipulator and the base spacecraft, with this phenomenon being particularly pronounced in mini space robots. The uncertainty surrounding the inertial parameters of space robots often renders dynamics-based controllers ineffective, and identifying these parameters in an on-orbit environment poses significant challenges. In this paper, we propose an adaptive controller for dynamic approximation that is specifically designed for mini space robots. This controller employs a linear separation of inertial parameters and utilizes recursive least-squares and Lyapunov methods to update the inertial parameter vectors. Simulation results validate the effectiveness of this adaptive controller in enabling mini space robots to accurately track predefined trajectories. Additionally, we compare the effects of the two parameter update methods on the controller stability under varying prior inertial parameter errors. The proposed inertial parameter separation adaptive controller significantly approximates the dynamics of mini space robots and facilitates precise on-orbit control, thereby offering considerable potential for advancing space exploration, satellite missions, and robotic operations. [ABSTRACT FROM AUTHOR]