A millimeter power synthesizer based on a novel suspended microstrip transition structure has been proposed. The terahertz power combiner combines/distributes power through a traditional waveguide power splitter with one to eight channels, and connects the eight channels of power splitters with a new suspended microstrip transition structure. The proposed new microstrip transition structure is easy to process, and by optimizing the length of the suspended microstrip substrate, the two sides of the substrate are mounted in the protruding waveguide sidewalls, which can suspend and fix the entire microstrip inside the waveguide without affecting transmission performance. The average insertion loss test values of the processed samples remained stable below 0.5 dB. Finally, the overall optimization analysis was conducted on the power combiner. Simulation results showed that within the operating frequency range of 180~220 GHz, the S11 parameter of the power combiner remained stable below -15 dB, and the loss from the input port to the output port of the power combiner was approximately 0.25 dB.

With the rapid development of network real-time system, in order to achieve more efficient communication, the problem of network resource scheduling has been widely concerned by experts and scholars. The static scheduling table is an effective solution for configuring network resources, which is the focus of research in related fields at home and abroad. Since the advent of TTE (Time-Triggered Ethernet) in 2002, the solution method of TTE network static scheduling table has been improved and innovated because of different application fields and specific use scenarios. With the continuous optimization of various algorithms, the generating effect of static scheduling table is more and more ideal, but the scheme still can not be applied to engineering practice. This paper proposes to select Sparrow Search Algorithm (SSA) and add disturbance to the individual optimal position, which can significantly improve the convergence efficiency of fitness function, avoid falling into local optimal, and achieve the purpose of solving TTE static scheduling table.

This paper introduces an application of QC-LDPC codes to telemetry system. At the same time, a joint design method of code length and telemetry frame length is proposed. Spectrum resources, channel qualities, and hardware capabilities are comprehensively considered in this design method, so that the optimal scheme can be designed. By using the RU encoding algorithm and the LLR BP decoding algorithm, a hardware implementation method based on FPGA and AD936X architecture is proposed. The coding gain of the designed system is simulated according to the technical route. Combining the theoretical analysis and simulation results, it can be seen that of the advantages of low latency and high gain, the proposed telemetry system design method has certain application value in future telemetry systems. In summary, the proposed method solves the problem of high coding delay in traditional telemetry system, and brings about 8 dB coding gain at the cost of minimal delay.

To ensure the security of authentication and key distribution in the space information network, this paper proposes a public-key management scheme based on the elliptic curve cryptosystem. With the capacity for network access authentication and key agreement/update, this scheme can achieve various security goals, such as authenticity, anti-replay, and forward/backward security. For interstellar authentication and key agreement, our scheme only requires 3 interactions between the satellites. We provide a security and efficiency analysis for our scheme, and show that the proposed scheme not only satisfies the actual availability in the space information network, but also performs better than other existing public-key management schemes.

There are more and more applications of change detection methods based on deep learning in high-resolution remote sensing images. However, downsampling and cropping strategies deployed to fit the GPU (Graphic Processing Unit) memory constraints on processing large-size remote sensing images often result in incomplete semantic information and loss of fine details. In this paper, a collaborative supervised network based on feature pyramids is proposed to enable the network to learn local and overall features from cropped and downsampled image blocks. In addition, a feature-sharing mechanism is introduced to fuse global features and local features. We evaluated the network on the LEVIR-CD (a remote sensing change detection dataset) and S2Looking (a building change detection dataset) by comparing it with some representative change detection networks. The comparison experiments show that the proposed network performs better in multiscale change detection, with a 2.69% improvement in precision on LEVIR-CD, and 6.83% and 2.68% improvement in precision and recall on the S2Looking dataset, respectively.

In order to find a carrier-to-noise ratio estimation method with low computation and strong practicality, this paper draws on the experience of the classical variance summing method and proposes an improved algorithm. The distribution of the absolute value of the I-branch accumulative value is deduced when stably tracking GPS signals, and an expression for estimating the carrier-to-noise ratio is given based on its statistical characteristics. The Q-branch accumulative value is not necessary in this algorithm. From the aspects of estimation accuracy and computation, the improved algorithm is verified by simulation and actual measurement data analysis. The results show that the overall performance of the improved algorithm is equivalent, with an error of less than 0.4 dBHz, the stability is better than that of the classical variance summing method and narrow to wide power ratio method, and the computation is reduced by 50% compared to that the classical algorithm. The method has certain practicality in some receivers with limited hardware resources.

X-ray communication technology is a kind of space communication mode using X-ray as a carrier, which has the advantages of a large communication bandwidth, light weight, small volume, low power consumption, and high confidentiality. By designing a multi-target X-ray signal modulation device, the X-ray communication rate can be improved, and the accuracy of X-ray energy spectrum recognition at the signal receiving end can be ensured, so that the advantages of X-ray communication based on energy load can be truly played. In this paper, an X-ray communication demodulation method based on peaking multi-level support vector machine is proposed to accurately identify the X-ray characteristic energy spectrum of multi-target materials. A peaking multilevel support vector machine classifier suitable for four-element communication is designed. The parameter tuning and verification ensure high accuracy and generalization ability. The simulation results show that support vector machine provides an efficient, accurate, and robust signal recognition solution for X-ray communication based on energy load.

The Phase Gradient Autofocus (PGA) algorithm is widely used to compensate for phase errors in Synthetic Aperture Radar (SAR) images. In the processing flow of the PGA algorithm, the two-step operation of selecting points and adding windows has a significant impact on algorithm performance. Traditional PGA algorithms often suffer from poor point selection quality or incorrect window width estimation, leading to poor focusing effect and slower convergence speed. This article proposes a strong point selection method based on the maximum energy signal-to-noise ratio criterion and an adaptive window width estimation method. Using the dimensions of energy and signal-to-noise ratio, ideal isolated strong scattering points are selected from image data, and two traditional windowing methods are combined and improved to adaptively estimate the window width, achieving improved algorithm stability and convergence speed. The simulation and experimental data processing results confirm the effectiveness of the algorithm proposed in this paper.

In order to solve the networking communication problem of the main-subsidiary satellite cluster under discrete and sparse topology and to ensure the demand of real-time interactive remote control telemetry and task information between satellites,this paper proposes a set of communication system architecture and inter-satellite networking protocol stack design scheme according to the hierarchical and clustered spatial topology characteristics. Firstly, in the design of the network layer, the data structure of the network layer, the subnet cluster head selection backup mechanism based on the multi-weight priority cost function and the process of the sub-satellite network access are given respectively. Secondly, in the data link layer, the data is processed hierarchically according to the subcontracted remote control and subcontracted telemetry system. Then, in the design of the physical layer, the spread frequency hopping is used as the communication system of the inter-satellite link, and the time division multiple access method is used to realize the multi-user communication of the satellite cluster, and the specific communication index of the inter-satellite link is given. Finally, the link calculation of inter-satellite communication is carried out. The calculation results show that the physical layer design meets the communication requirements of each satellite.

Compared to 32QAM technology, 32APSK technology reduces the number of amplitudes and is suitable for a nonlinear channel in a relay satellite communication system. TCM technology combines channel coding and multi-level modulation,doesn't increase the spectrum bandwidth, decreases the transmission power, cuts down energy consumption, lowers the requirements for technical indexes of the power amplifier, and is beneficial for achieving lightweight and miniaturization of satellite payloads. This paper combines 32APSK technology and TCM technology, proposes a kind of 32APSK-TCM technology, discusses details of the 32APSK-TCM technology constellation subset splitting method and constellation point selection method, and analyzes the performance of the 32APSK-TCM technology. This paper simulates the 32APSK-TCM technology and 16APSK technology using the simulation platform of the relay satellite communication system developed by our research team. Simulation results demonstrate that under the condition of an ideal channel, I/Q amplitude phase imbalance, amplitude frequency characteristics, group delay, phase noise, power amplifier saturation point, and nonlinear channel, if the maximization value of the required bit error rate is 1E-6, compared to 16APSK technology, the minimization value of the signal-to-noise ratio of 32APSK-TCM technology saves 13.29 dB, 13.29 dB, 14.84 dB, 15.54 dB, 15.11 dB, 15.77 dB, and 16.37 dB, respectively.