ETC International

Waveform design is a critical technology for orthogonal time-frequency space (OTFS) integrated sens-ing and communication (ISAC) systems. Existing research mainly focuses on the design of multiple-input multiple-output (MIMO)-OTFS communication waveforms or the design of dual-functional OTFS waveforms for single-input single-output (SISO) systems, which results in degraded per-formance in dynamic, multi-user ISAC scenarios. To address these limitations, the paper mainly investigates waveform op-timization for MIMO-OTFS ISAC systems, which formulates the problem as minimizing the weighted integrated sidelobe level (WISL) under peak-to-average power ratio (PAPR) and multi-user interference (MUI) energy constraints. Due to its non-convex nature with multiple constraints, the problem is challenging to solve. To address the complicated optimization problem, an adaptive penalty analytic subproblem decompo-sition (APASD) method is proposed. First, auxiliary variables are introduced to decompose the original problem into several subproblems with analytic solutions. Then, leveraging the structure of the subproblems, we derive the corresponding analytic solutions. Finally, the penalty parameters are adap-tively updated based on the residuals, and the overall problem is iteratively refined until convergence. Simulation results demonstrate that the proposed method can achieve a lower sidelobe level while ensuring the achievable sum-rate, and shows better performance than existing methods.

Automatic Gain Control (AGC) is a fundamental mechanism that ensures the stability of signal processing in radar systems operating over a wide dynamic range. This paper proposes a digital AGC design and FPGA-based implementation method for a secondary meteorological radar. The proposed approach employs a multi-strategy adaptive AGC algorithm that effectively addresses the instability of output signals under large dynamic input conditions. Experimental and engineering applications verify that the designed digital AGC system features fast response time, small steady-state error, and wide dynamic range. The system effectively prevents receiver saturation and signal distortion, thereby improving the signal-to-noise ratio and measurement accuracy.

Abstract. With the rapid development of low-altitude economy in China, path planning for low-altitude aircraft faces challenges such as strong environmental dynamics, complex constraints, and difficult real-time decision-making. To achieve efficient and universal path planning capabilities, this paper proposes a three-layer Spatiotemporal knowledge graph(3L-STKG) architecture comprising a conceptual layer, an instance layer, and a spatiotemporal layer. Guided by ontological spatiotemporal knowledge, this architecture enables efficient route planning in complex scenarios and addresses the challenges of path planning in low-altitude environments. The proposed method pre-matches the maneuverability constraints from the conceptual layer with the grid traversal attributes of the spatiotemporal layer through a cross-layer semantic association mechanism, dynamically constructing an accessible correlation network. On this basis, the path planning problem is transformed into a minimum weighted connected subgraph search problem in the ontology-constrained spatiotemporal network, and an improved A* algorithm is used to solve for the global optimal path. The experimental results show that the planning time in specific scenarios is reduced by 88.54% compared with traditional methods, while supporting rapid adaptation to multiple aircraft types. The research results provide a theoretical framework for intelligent decision-making of low-altitude aircraft in complex environments and have broad application prospects in fields such as emergency rescue and urban logistics.

With the advancement of electronic warfare, radar waveforms with low probability of intercept (LPI) characteristics have attracted increasing attention. In this paper, we propose a novel LPI waveform design method that can minimize the cyclic frequency sidelobes to enhance LPI performance under the constraint of autocorrelation-function peak sidelobe ratio (ACFPSLR) to maintain detection capability. In the proposed method, the weighted sum of cyclic frequency sidelobes is used as the LPI performance metric based on cyclostationary spectrum analysis (CSA). Under the power and ACF-PSLR constraints, the LPI radar waveform design is formulated as a non-convex quartic optimization problem. By introducing auxiliary variables, it is transformed into multiple quadratic subproblems with independent variables and linear inequality constraints, which can be efficiently solved via the alternating direction method of multipliers (ADMM). Simulation results verify that the proposed method can achieve better LPI performance while satisfy the demand of target detection.

With the improvement of satellite capabilities and the rapid development of gallium nitride (GaN) device technology, the requirements for signal power are increasing. GaN solid-state power amplifiers (SSPA) have significant advantages over traveling wave tube amplifiers (TWTA) in terms of installation size, weight, and reliability.This paper presents a band solid-state power amplifier implemented using domestic GaN power devices and multi-chip module (MCM) circuit modules, operating at a frequency of 8-8.2 GHz, with a saturated output power greater than 15 W, an efficiency of 38%, a weight of only 0.9Kg, and a measured amplitude linear error (EVM) value within 9% under rated output.By skillfully utilizing current sampling feedback design, output stability and linearity under extreme operating temperatures are achieved, ensuring the quality of data transmission communication. The results of the accelerated life test show that the SSPA can meet the system's service life requirement of over 8 years.

To enhance the efficiency of aviation emergency rescue and address issues such as unclear situational awareness, poor communication, and dispersed intelligence data in rescue command, this study proposes a design scheme for an Emergency Rescue Command and Information Fusion System for rescue command aircraft. The system is designed to command, dispatch, and handle emergencies during rescue operations. Developed based on GIS (Geographic Information System) and utilizing a Client-Server (C/S) architecture, the system integrates functionalities including situational awareness, command and dispatch, and system management. Once deployed, this system will effectively fill the gap in airborne rescue command systems within China's aviation emergency rescue domain and significantly improve rescue efficiency.

O presente artigo analisa o salário-maternidade no Brasil, com enfoque na interpretação do Supremo Tribunal Federal (STF) na Ação Direta de Inconstitucionalidade (ADI) 2.110, que questionou a exigência de carência diferenciada para a concessão do benefício. A decisão declarou inconstitucional a diferenciação de períodos de contribuição mínimos entre categorias de seguradas, consolidando o entendimento de que o salário-maternidade é um direito fundamental de proteção à maternidade, não condicionado a critérios que restrinjam o acesso de mulheres em situação de vulnerabilidade. Nesse contexto, surge o problema de pesquisa sob o formato do seguinte questionamento: de que maneira a decisão da ADI 2.110 contribui para a inclusão previdenciária de mulheres e para a efetivação de direitos constitucionais relacionados à maternidade? A pesquisa adota metodologia qualitativa, baseada em revisão bibliográfica e análise jurisprudencial, incluindo doutrinas, artigos acadêmicos e decisões judiciais. Os objetivos do estudo foram: geral – analisar os efeitos da decisão do STF na ADI 2.110 sobre a concessão do salário-maternidade; específicos – (1) compreender a fundamentação constitucional da decisão; (2) identificar os impactos jurídicos da declaração de inconstitucionalidade da carência diferenciada; (3) avaliar os impactos sociais e práticos para mulheres em situação de vulnerabilidade; e (4) comparar a evolução jurisprudencial entre a ADI 2.110 e decisões posteriores, como o RE 576.967/PR. Conclui-se que a ADI 2.110 representa um marco jurídico e social, consolidando o salário-maternidade como instrumento de proteção integral à maternidade e cidadania feminina.

Fiber optic gyroscope (FOG) is an essential component of the photoelectric equipment servo system, and its performance degradation during operation can result in the failure of overall equipment causing undesired safety concerns. Therefore, the failure mode, effects, and criticality analysis (FMECA) approach is used in this paper to conduct the degradation-based reliability modeling and assessment of the device and to identify its weakest link. The applied approach for the FOG device indicates its high reliability within 7000 hours of operation being consistent with the actual engineering. The proposed method and analysis result presented in this research can provide a reference for investigations on the reliability of FOG.