The high-precision navigation of the remote sensing instruments onboard FengYun-4 (FY-4) geostationary meteoro-logical satellite is the basis for instrument calibration, product retrieval, and quantitative application. The geosynchronous interfero-metric infrared sounder (GIIRS) onboard FY-4 satellite, the new generation geostationary meteorological satellite in China, is the first hyperspectral vertical detector operating in the geostationary orbit in the world. In the process of hyperspectral detection, it is key to keep the "resident" observation target stable with high precision. The FY-4 satellite uses an advanced three-axis stable attitude control platform, which brings great flexibility to earth observation and great challenges to the high-precision navigation of the GIIRS. The stability of the high-precision observation target requires the cooperation of satellite platform, attitude control, the instru-ment and the ground system, which process is very complicated. Based on the introduction of the detection principle and working mode design of the GIIRS, the key technology of satellite-ground integrated navigation is researched. The resident accuracy as well as the navigation accuracy are tested and analyzed using the measured data from the GIIRS in orbit. The results show that the GIIRS achieves a resident accuracy of 1/10 pixel and a navigation accuracy of 1 pixel, laying a good foundation for quantitative applications including numerical weather prediction.

Clouds and precipitation are vital to the global water and energy cycle and act as crucial elements in maintaining the Earth's energy balance. Spaceborne cloud and precipitation radars can actively detect clouds and precipitation and obtain three-dimensional structural information of cloud and precipitation globally all day and night,effectively filling the shortcomings of pas-sive detection by meteorological satellites. Firstly, the demand analysis is conducted on spaceborne cloud and precipitation radars,summarizing the shortcomings of cloud and precipitation detection capabilities of current Chinese meteorological satellites. Then,the development status of spaceborne cloud and precipitation radars at home and abroad is introduced, and the problems that China's spaceborne cloud and precipitation radars need to be solved are summarized. Finally, we give the main direction of the development of spaceborne cloud and precipitation radars in China in the future.

China's first precipitation measurement satellite has been successfully launched in April 2023, combining active and passive microwave instruments dual-frequency precipitation measurement radar and microwave imager to carry out high precision precipitation detection. In view of the limited coverage of precipitation measurement radar, the radar reflectivity factor data of wide swath radar is developed by using the microwave radiometer imager data of the same platform and the deep learning model, and the coverage of 2.67 times the width of precipitation measurement radar is achieved, which significantly increases the observation range of precipitation measurement radar. Taking Typhoon "Tali" in 2023 and extreme short-time heavy precipitation in North China as examples, the application potential of the wide swath results generated by the service is analyzed. The calculation result of the radar re-flectivity factor of wide swath radar is consistent with that of ground based radar, which has a good reference in practice. In the ground system operation scheduling, in order to support the continuous high-timeliness calculation of wide swath radar reflectivity factor data, this paper designs the wide swath radar reflectivity factor operation flow, comprehensively considers the resource con-sumption, timeliness and reliability of the operation implementation, and proposes the best data-driven operation scheduling strategy,which can effectively reduce the running time and improve the timeliness.

From March 27-29, 2021, a large-scale and prolonged dust pollution event occurred in the north of China. This study analyzed the optical properties, vertical distribution, and transport patterns of dust aerosols using data from MODIS and ground-based lidar (AMPLE-001), combined with the HYSPLIT model. Additionally, hourly data from the China Environmental Monitoring Station and aerosol optical depth (AOD) data from MCD19A2 and AERONET were used to verify the accuracy of the ground-based lidar measurements. The key findings are as follows: ① The dust was primarily transported at an altitude of 4 km over the northern Gobi Desert, and mixed with local pollutants and then settled. ② During the dust event, particulate matter concentrations surged dra-matically. PM₁₀ concentrations peaked at over 2 492.65 μg/m³, while PM_2.5 reached a maximum of 236.48 μg/m³. The highest record-ed AOD was 4.1, with dust pollution being most severe in the southern and eastern parts of Beijing, Tianjin, and Hebei. ③ In terms of accuracy validation, comparisons between AOD values from sun photometers and lidar showed a strong correlation, with a corre-lation coefficient of 95.63%. Similarly, the PM₁₀ and PM_2.5 data from ground-based lidar were highly consistent with official monitor-ing data, with correlation coefficients of 85.93% and 98.47%, respectively. These results validate the detection capability and accura-cy of the AMPLE-001 ground-based lidar system.

The Surface Water and Ocean Topography (SWOT) satellite is a new generation ocean observation satellite. It is used to provide a new method for wave detection by adopting the synthetic aperture radar (SAR) observation system at a small inci-dence angle. Based on previous studies on SAR wave spectrum inversion, the applicability of the wave spectrum inversion algorithm for SWOT satellite data is studied. The effects of wind speed, wind direction, and main wave direction on wave spectrum inversion are discussed. The effective wave height of the inversion is verified using the ERA5 dataset from the European Center for Mediumrange Weather Forecasts (ECMWF). The results show that the root mean square errors (RMSE) of the effective wave height inver-sion are 0.30 m, 0.19 m, and 0.64 m at wind speeds of 7-9 m/s, 9-11 m/s, and >11 m/s, respectively. The scatter indices (SI) are 16.74%, 7.03%, and 19.61%, respectively. It can be proven that the SWOT satellite, as a small incidence angle SAR, has the poten-tial to invert wave spectra and wave parameters.

As one of the earth orientation parameters, UT1-UTC characterizes the irregularities of the earth rotation speed, and plays an important role in many space exploration activities such as space autonomoμs navigation, deep space probe orbit determination. Yet China has not established the relatively stable independent guarantee ability of UT1-UTC, it is of great reference signifi-cance to carry out UT1-UTC determination simulation at the early stage of system planning and construction. In this paper, the Mon-te Carlo simulation analysis of UT1-UTC solution is carried out by μsing VieSked++ software, and the measured data is utilized to verify the simulation conclμsions. Firstly, the IVS conventional observation mode is simulated, and subsequently about 100 times of IVS conventional observation data are used for comparison and verification. The results show that the actual solution accuracy is about 1.4 times of the repeatability factor. Secondly, the UT1-UTC intensive observation simulation is carried out for the single base-line of the Chinese deep space network, which is located in the northern and southern hemispheres, respectively. The simulation re-sults show that the UT1-UTC solution accuracy of the JM-KS baseline and the NM-AG baseline of the deep space network is expect-ed to be about 18 μs and 22.4 μs, respectively. Furthermore, the real observation data by JM-KS baseline of China deep space net-work are used for resolving UT1-UTC to verify the simulation result. Finally, on the basis of deep space network station resources,the simulation of multi-station and multi-baseline UT1-UTC monitoring capability is carried out. The results of this paper effectively evaluate the ability of UT1-UTC monitoring based on single baseline of China deep space network, and provide reference for subse-quent system construction and UT1-UTC solution ability evaluation.

This paper introduces an MSK non-coherent demodulation algorithm that integrates the soft spreading spectrum of CCSK, addressing the issue of signal demodulation in noisy environments. MSK modulation is widely used due to its efficient spec-tral utilization and low bit error rate, but traditional coherent demodulation relies on accurate carrier phase information, which is not suitable for short-burst communication and high-dynamic environments. The algorithm combines CCSK spreading technology, using base functions with strong periodic auto-correlation characteristics and their cyclic shift sequences, and proposes a waveform-matching-based MSK non-coherent demodulation algorithm, which significantly enhances the anti-interference capability, simplifies the receiver design, and maintains good demodulation performance under low signal-to-noise ratio conditions, with a high degree of tolerance to the sampling point drift. The simulation results show that under a signal-to-noise ratio of -5.5 dB, the system's bit error rate (BER) can be kept below 10^-6, demonstrating excellent noise resistance. Additionally, simulation experiments analyzed the im-pact of sampling point drift, revealing that a 1-sample point drift can cause 2-3 dB decrease in demodulation performance, while a 2-sample point drift can contribute to a 5-6 dB decrease, yet the demodulation performance remains within an operational range. The algorithm demonstrates outstanding demodulation performance under low signal-to-noise ratios and in high-dynamic scenarios. In conclusion, the waveform-matching-based MSK non-coherent demodulation algorithm proposed in this paper offers an efficient and reliable solution for wireless communication in complex environments.

This paper introduces the composition, major function, and technical specifications of a high integrated eight-channel Ka-band low noise down-converter module. An eight-channel Ka-band low noise down-converter module is designed, and the imple-mentation method of the circuit is proposed. The isolation, amplitude imbalance, noise figure (NF), and combined frequency interfer-ence are also analyzed. The measured results of the module are as follows: NF is lower than 2.3 dB, the converter gain is more than 35 dB, and the amplitude imbalance is lower than ±0.5 dB. The isolation of multi-channel is more than 60 dB. The module has the advantages of a small size, high output power, high reliability, and good consistency. It has been successfully applied in TT&C.

The paper provides a brief overview of the development of terahertz technology and its advantages in various appli-cation scenarios, including high resolution and strong anti-stealth characteristics in radar. Regarding terahertz atmospheric transmis-sion characteristics, the paper focuses on the basic principles of the MPM and provides an overview and comparison of mainstream atmospheric transmission models like the ATM model and AM model. At the same time, this paper also introduces recent research developments and progress on terahertz atmospheric transmission characteristics domestically and internationally. Finally, this paper summarizes the development of terahertz technology and offers prospects for its applications.

DRO orbit in cislunar space is a kind of periodic orbit with great value and mission potential. The scientific exploration satellite on DRO orbit has the requirement of timely down-transmission of critical buret data of scientific payload and global coverage of measurement and control management. This paper analyzes the basic capability of BDS-3 global short message. The cis-lunar space TT&C data transmission scheme and TT&C data transmission process are designed based on the BDS-3 global short message, and the key technologies are analyzed. The research and analysis show that the cislunar space TI&C data transmission scheme based on the BDS-3 global short message can make up for the gap of ground-based TT&C, and realize the low-cost TT&C data transmission in all weather and all day.

Aiming at the issue of poor stability of visual localization and mapping (SLAM) methods during dynamic low-altitude flight of unmanned aerial vehicles (UAVs) in the absence of navigation signals, this paper proposes a UAV visual localization method based on edge features, which generates the edge features by downsizing the traditional feature extraction algorithm and finally completes the position estimation by nonlinear optimization. A convolutional neural network is employed to match edge fea-tures between consecutive key frames, yielding an edge feature reprojection error function, and finally the position estimation is com-pleted by nonlinear optimization. The experimental results demonstrate that compared to the state-of-the-art ORB-SLAM3 algo-rithm, the proposed method reduces localization time by 31% on the dataset and improves localization accuracy by 15.04% in low-texture scenes. Flight experiments further indicate a significant enhancement in the accuracy and stability of UAV localization.

The optical phased array controls the emission beam by adjusting the phase of the array antenna to change the wave-front, thus achieving control over the emission beam. Optical phased array technology has great potential applications in areas such as laser radar, laser communication, high-brightness laser generation, and synthetic aperture detection. This article reviews the re-search progress, advantages, and disadvantages of liquid crystal phased arrays, micro-electro-mechanical system phased arrays, and optical waveguide phased arrays. It also delves into the optical waveguide phased array technology in laser radar, proposing break-through directions for this technology.

Considering cost and integration constraints, traditional phased array antennas are usually single-polarized or time-multiplexed polarized and do not finely regulate the polarization form when transmitting or receiving signals, which constrains the polarization domain efficiency of phased array antennas. To address this issue, this paper is based on heterogeneous fully polarized phased arrays and jointly regulate their beam pointing and polarization parameters, in an attempt to achieve the full polarization ap-plication of phased array antennas at a lower cost. Firstly, the concept of heterogeneous fully polarized phased arrays is proposed;then, the mathematical model for the joint regulation of beam pointing and polarization parameters of heterogeneous fully polarized phased arrays is established; finally, a joint regulation method is proposed and mathematically simulated. The simulation results dem-onstrate the correctness and effectiveness of the joint regulation method for beam pointing and polarization parameters of heteroge-neous fully polarized phased arrays.

In order to achieve high-precision remote sensing inversion of suspended particulate matter concentration in the seas surrounding the Yellow River Estuary, this paper constructs seasonal models for spring, summer, and autumn, as well as a cross-seasonal model, utilizing GOCI-I image data and based on the WOA-BP algorithm. These models are compared with multiple algo-rithms such as Catboost, RF, KNN, BP and so on. The results reveal that within each seasonal model, the WOA-BP algorithm exhib-its superior performance on both the training and testing sets, with the average relative errors for the respective seasonal testing sets being 24.18%, 25.97%, and 29.42%. When the cross-seasonal testing set is employed to evaluate the three models, and their accura-cy is found to be significantly lacking, which indicates that seasonal models are not applicable across different seasons. In the cross-seasonal model, the WOA-BP algorithm again demonstrates the highest accuracy, with an overall average relative error of 26.96%. The average relative errors when testing with the three seasonal testing sets are 25.80%, 21.90%, and 37.17%, respectively. While the accuracy for summer is improved, the accuracy for the other two seasons falls below that of the corresponding seasonal models,with autumn experiencing the greatest decline in precision. Therefore, it is suggested that the cross-seasonal model be employed for spring and summer, whereas the appropriate seasonal models are recommended for autumn.