With the increasing number of space debris and the increasing complexity of spacecraft missions as well as the requirements for adaptability to extreme environments, the operational status, damage diagnosis, life prediction and reliable safety as-sessment of spacecraft structure are particularly important. Operating as an effective approach, spacecraft structural health monitoring obtains structural feature information through sensor systems deployed in the structure，analyzes and evaluates the structural status through algorithm processing, thereby ensuring the safe and stable operation of the spacecraft at all stages. This paper focuses on the key technologies of spacecraft structural health monitoring. Firstly, from the sensor end of information acquisition, the technical characteristics, application status, current problems and development directions of optical fiber sensing, acoustic emission sensing and surface acoustic wave sensing are reviewed. Then, the research progress of sensor deployment methods and diagnostic evaluation algorithms for information processing is introduced. Secondly, the development trends and main challenges of spacecraft structural health monitoring are summarized and prospected.

Micro capacitive pressure sensors have important application value in fields such as biomedicine, drone positioning, and wearable devices. This study focuses on MEMS capacitive gauge pressure sensors. A high-precision capacitive pressure sensor is designed and fabricated for implantable biomedical applications. This device is formed by anodic bonding between a glass substrate with fixed electrodes and an SOI wafer with elastic membranes. The elastic membrane will deform when the pressure on both sides changes, resulting in a change in the capacitance of the device. The readout circuit calculates the external pressure by detecting changes in capacitance. This paper improved the nonlinearity of capacitive pressure sensors by designing a structure of a boss on the membrane. The result from ANSYS finite element simulation shows that the nonlinearity was improved from about 17% (flat membrane) to 7% (with boss structure). The structure of the boss was formed by anisotropic etching of silicon with TMAH, and the SOI buried oxide layer serves as the stop layer of etching to achieve high device consistency. Finally, a packaging and testing platform is built for capacitive pressure sensors and calibration. In the measurement range of 0 ~ 40kPa relative to atmospheric pressure, this device achieved a testing accuracy of 0.30%, nonlinearity of 8%, and repeatability error as low as 0.09%.

In the field of ultra-high sound pressure noise environment of rocket engines, fiber laser microphones without diaphragm packaging have prominent pressure-resistant advantages. However, the phase noise problem introduced by unbalanced interferometer in engineering applications limits their performance. This paper focuses on the phase noise of the fiber laser microphone array introduced by the unbalanced interferometer in the modulation system. Firstly, the working principle of the modulation system and the source of the phase noise of the unbalanced interferometer are discussed, and a stable laser light source is incident on the unbalanced interferometer shared by the microphone system, to construct fiber laser microphone array system with suppressed optical phase noise. Then, the suppression principle is theoretically analyzed using the differential cross multiplying (DCM) demodulation. The noise information of the optical reference is used to cancel out the system noise introduced by the interferometer, thereby achieving the dynamic noise suppression. Finally, numerical simulation and experimental verification are conducted on the microphone array system. As a result, the phase noise measured in the non-equilibrium interferometer is reduced from approximately ± 0.34 rad to within ± 0.15 rad compared with the system without optical reference under field experimental conditions. The noise peak is sup-pressed by more than 7 dB, and the noise power spectral density is reduced from -25.02 dB/ to below -32.93 dB/. The suppression effect of phase noise is significant.

To meet the application requirements of inertial navigation, autonomous driving, and other fields, and to advance the development of micro-electromechanical systems (MEMS) silicon gyroscopes towards high precision, digitalization, and miniaturization, this paper presents the design and implementation of a MEMS silicon gyroscope interface ASIC with digital output, based on a 0.35 μm BCD process and a monolithic integration approach. A closed-loop drive scheme based on noise self-excitation is adopted, enabling the gyroscope to achieve harmonic vibration in the drive direction. The detection circuit uses a low-noise capacitive-to-voltage (C/V) conversion circuit to efficiently convert the small displacement signal into a voltage signal. Signal processing is performed using switched-capacitor phase-sensitive demodulation technology, combined with low-pass filtering, effectively suppressing noise interference and yielding a low-noise analog angular velocity output signal. To achieve the digital output of the silicon gyroscope's angular velocity, an integrated fourth-order feed-forward Sigma-Delta (ΣΔ) analog-to-digital converter (ADC) is designed to convert the analog angular velocity signal into a digital signal. The chip test results show that the dynamic range of the ΣΔ modulator reaches 110 dB, with a low-frequency noise floor of approximately -120 dB. The overall range of the gyroscope is ±200(°)/s, with a scale factor of 21 310 LSB/((°)/s), a nonlinearity of 178×10^-6, bias instability of 0.259(°)/h, and angle random walk of 0.028 7(°)/√h. The chip area is 4.3 mm×4.3 mm. By using the integrated interface ASIC to replace the traditional PCB-level system, the system's integration is significantly improved, successfully meeting the miniaturization requirements for MEMS silicon gyroscopes and promot-ing their development in high-precision digital applications.

Solid rocket motors are widely used in space launch vehicles, missile weapon propulsion, and spacecraft attitude and orbit control. Its tail flame temperature is a key parameter in evaluating propellant combustion performance and the engine efficiency. Due to the high temperature, high pressure and strong washout characteristics of the solid rocket motor exhaust flame, the test site environment is often accompanied by strong vibration, strong stray radiation, dust pollution and high noise, it's a challenge to temperature measurement techniques. In this paper, the development of contact and contactless temperature measurement techniques for solid rocket motor exhaust flame is summarized, and the advantages and disadvantages of the current techniques are analyzed. It is also pointed out that multispectral radiometric imaging thermometry and its temperature inversion algorithm are the current and future research frontiers.

Polymer Derived Ceramics (PDCs) thin-film thermocouples have the advantages of a simple preparation process and a stable high-temperature performance. They are very suitable for temperature measurement of hot-end components such as aircraft engine turbine blades. However, as the operating temperature of advanced engines increases, the upper limit of their temperature resistance needs to be improved. This article develops a precursor ceramic encapsulated PDCs: ITO/In₂O₃ thin film thermocouple. The encapsulation layer uses SiCN as the precursor solution and nano-Al₂O₃ powder as the filling material, and is prepared by the screen printing process. High-temperature test results show that the prepared sensor can survive at 1 500 °C in the short term and have stable output within 1 400 °C. The calibration test at 1 100 °C shows a linearity better than 0.999, with a multiple-cycle error of less than 1%.

The operating temperature of common acrylic-coated optical fibers is usually -65 °C to 80° C, and the working temperature of common high-temperature polyimide-coated optical fibers is up to 300 °C. At higher temperatures, metal-coated special optical fibers, such as aluminum-coated, copper-coated, and gold-coated fibers, are usually used for signal transmission. In this paper, the transmission loss of gold-coated fibers is tested at different ambient temperatures, and it is found that the transmission loss of gold-coated fibers varies greatly when the ambient temperature changes. For fiber optic temperature sensors based on the blackbody radiation principle, the error introduced by the variation in transmission loss can exceed 60 °C. On this basis, based on the transmission characteristics of light in different bands in gold-coated fibers, a dual-band correction method is proposed, which can correct the transmission loss of optical fibers caused by ambient temperature. After the correction, the error caused by the transmission loss is less than 15 °C.

The current wireless SAW (Surface Acoustic Wave) sensor based on langasite (LGS) can work at temperatures as high as 600 °C. Nevertheless, the propagation loss of LGS increases significantly as frequency and temperature increase, which limits the operating frequency of the SAW sensor based on LGS to 1 GHz. However, SAW resonator based on AlN/sapphire structure exhibits gigantic potential for high-temperature sensing applications due to its resistance to high temperatures, high Q-factor, and low propagation loss. In this work, an efficient model for SAW resonator based on AlN/sapphire is developed using the coupled mode (COM) theory combined with the finite element method (FEM). The influence of different numbers of interdigital transducers(IDT), reflective gratings, and different aperture lengths on device performance are investigated. Furthermore, the relationship between resonant frequency and temperature at various temperatures is simulated, which compares well with that of the experimental results. The investigation results show that the resonator works reliably in the temperature range of up to 500 °C and the operating frequency of up to 2.45 GHz. The frequency-temperature characteristics exhibit good linearity, with a temperature coefficient of-67×10^-6 °C^-1. This work provides an important reference for designing high-performance SAW high-temperature sensors.

Proper total pressure, temperature and humidity environment in the cabin are the basic conditions for the stable operation of the space station platform and the safety of astronauts. For the long-term and reliable measurement of the total pressure, temperature and humidity environment in the cabin, an intelligent integrated monitoring technology and instrument are introduced, including the overall design, sensor design, integration challenges and calibration scheme. From the verification of on-orbit data, it is concluded that the instrument can achieve high-precision and high-reliability measurement of the total pressure, temperature and humidity in the cabin. It not only improves the level of environmental measurement in China's space station, but also provides new technical support for environmental detection of the manned space program in the future.

Aiming at the temperature measurement requirements of fiber grating sensors, this paper proposes and implements a Zynq-based Fiber Bragg Grating (FBG) temperature demodulation system. The system adopts the Zynq architecture, and the acquisition of FBG spectra and the calculation of the center wavelength are realized in the hardware system. Through the analysis and optimization of Gaussian fitting peak-seeking algorithm, the matrix operation is used to reduce the amount of curve-fitting operations, and the FBG center wavelength solving is realized in the hardware system, which takes into account the demodulation accuracy and at the same time, improves the demodulation rate and real-time performance of the system. The miniaturized fiber grating temperature demodulation system developed has a wavelength demodulation range of 1 510 nm ~ 1 590 nm with a stability of ±2 pm, which has a good potential application value in structural monitoring and other fields.

Fiber Optic Gyroscope (FOG) is the core component of the fiber optic strapdown inertial navigation system, which has been widely used in aviation, aerospace, navigation and other fields. The scale factor is the main factor affecting the dynamic performance of FOG. Because the photoelectric devices inside FOG are highly sensitive to temperature vaviations, the scale factor error will be produced under the influence of temperature, which will affect the precision of FOG. In the variable temperature environment, each photoelectric device is heated unevenly, which leads to the hysteresis of the scale factor error. In this paper, the scale factor hysteresis error of FOG is studied, and a multi-temperature sensor measuring system is built. The source and characteristics of the scale factor hysteresis error are determined by the experimental results. Based on the above analysis, an error compensation algorithm based on gravitational search algorithm (GSA) and long short-term memory (LSTM) network is proposed. The parameters of LSTM network are optimized by GSA, and the LSTM model is used to compensate the scale factor hysteresis error. The experimental results show that the peak-to-peak value of scale factor error in the whole temperature range is reduced from 835.1×10^-6 to 38.02×10^-6 by the proposed algorithm. By comparing with the compensation results of multilayer perceptron (MLP) and traditional LSTM algorithm, the effectiveness of the proposed algorithm in scale factor hysteresis error compensation is further verified.

It is of great significance to obtain accurate heat flux data for understanding the thermal environment and optimizing the thermal protection system of the flight vehicles. The important aspects of heat flux measurement technology development are heat flux calibration and heat flux data processing. The heat flux sensor based on the hybrid heat transfer principle needs to utilize heat flux terms from different sources, such as the heat storage term and the temperature difference term to achieve heat flux results during data processing. The error sources and the magnitudes of influence of these terms are different, resulting in limitations of the common single-coefficient calibration method. Especially when the testing time is longer, some error factors will cause changes in heat flux measurement error. This paper proposes a multi-coefficient calibration method that corrects each heat flux term using different coefficients separately. Based on the temperature data in the calibration test and the known input heat flux, the calibration coefficient matrix is solved using the least squares method. The analysis and processing results of the calibration testing data show that using the multi-coefficient calibration method, the heat flux results are in better agreement with the input heat flux than those using the single-coefficient method. With enough testing data, the calibration deviation is less than 5% within the calibration time.

In response to the demand for in-situ continuous measurement of molten steel temperature in the field of metallurgy, a novel contact-type continuous temperature measurement sensor structure scheme is proposed. The thermal response characteristics are analyzed by establishing a three-dimensional heat transfer model. Then a high-pressure process and a high-temperature annealing process are used to realize the preparation of an integrated sensitive component of thermocouple/ceramic protection body, which is then encapsulated inside the lance-type support structure of MgO-C material for making a temperature measurement sensor; Continuous temperature measurement tests are carried out under the environment of molten steel of Ladle Furnace, and the results show that in the 1 600 ℃~1 650 ℃ high temperature molten steel environment, the sensor can effectively measure temperature continuously for more than 16 minutes.

With the rapid development of 5G communication and millimeter-wave technology, the performance requirements for high-frequency passive interconnect structures in radio frequency (RF) microsystems have become increasingly critical. To address the efficiency bottlenecks caused by fragmented process data and isolated models in traditional design workflows, this paper proposed an independently developed 1~40 GHz silicon-based passive interconnect Process Design Kit (PDK). By integrating equivalent circuit models with HFSS full-wave electromagnetic simulation data, parameterized models for core structures such as grounded coplanar waveguide (GCPW) and micro-bump interconnects are established, and high-precision model matching is achieved through gradient optimization algorithms. The PDK development is completed on the Keysight ADS platform, including symbol libraries, parameterized cells, design rules, and verification workflows. Experimental results demonstrate that the developed PDK achieves a root mean square error (RMSE) of S-parameters below 10% across the 1~40 GHz frequency band. Based on this PDK, the simulation design of an X-band RF micro system was completed. The microsystem meets the specified performance requirements, verities the validity of the PDK. This PDK provides for reliable support for efficient design-process co-optimization in high-frequency RF systems.

In recent years, low-orbit navigation enhancement system has been gradually incorporated into the construction of integrated PNT system, and the capture and tracking of low-orbit signals has gradually become a hot research issue. In the scenario that the integrated PNT application terminal needs to receive BeiDou + LEO navigation augmentation signals at the same time, due to the large resource consumption of the capture module, using two sets of hardware resources to compatibly receive high, medium and low orbit-signals will cause a great waste of resources, and it is not possible to realize the small size and low power consumption requirements of the user terminal. This paper further optimizes the algorithm on the basis of the existing BeiDou signal capture module, and through the design of flexible and reusable matched filter plus FFT structure, on-chip distributed processing and off-chip ultra-long storage architecture, and techniques such as high Doppler pseudo-code, carrier frequency compensation, etc., it realizes the compatible reception of high, medium and low-orbit signals, and at the same time, it can realize the capture of high and medium orbit BeiDou B1C signals with a capture sensitivity of -145 dBm capture sensitivity and 40 kHz STL burst signal in low orbit.

This study explores the combination of t-Distributed Stochastic Neighbor Embedding (t-SNE) dimensionality reduction technique and the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm to address the challenges in multi-parameter radar signal sorting. As the complexity of radar signals has been increasing, traditional signal processing methods have revealed limitations. t-SNE effectively extracts essential features from the data by reducing dimensionality, eliminating noise and redundant information, and providing a clearer boundary for subsequent DBSCAN clustering. In the experiment, we generated five different types of radar signal data and conducted analyses using t-SNE and DBSCAN. The results show that the t-SNE dimensionality reduction combined with the DBSCAN clustering algorithm performs well in terms of purity and silhouette score, confirming the effectiveness of this method in complex radar signal sorting.

Spaceborne synthetic aperture radar is one of the important means of detecting ocean internal waves, and sea surface wind speed has a significant impact on the ability of synthetic aperture radar to detect ocean internal waves. Based on the theory of the influence of sea surface wind speed on the ability of synthetic aperture radar to detect ocean internal waves, combining the insitu measured parameters of ocean internal waves, additional with the corresponding ocean environment and synthetic aperture radar data, this paper analyzes the imaging mechanism of ocean internal waves on synthetic aperture radar images, discusses the different manifestations of upward and downward ocean internal waves, and elaborates on the ability of synthetic aperture radar to detect ocean internal waves under the combined influence of internal wave amplitude, thermocline depth, and thermocline intensity under different wind speed conditions. Simulation analysis shows that the smaller the sea surface wind speed, the larger the internal wave amplitude, the shallower the thermocline depth, and the stronger the thermocline intensity, the stronger the ability of synthetic aperture radar to detect internal waves in the ocean. The results can provide technical support for the planning of satellite observation tasks in the early stage of detecting ocean internal waves using spaceborne synthetic aperture radar.