Abstract:

With the continuous development of Radio Frequency(RF) devices, terahertz communication is evolving from point-to-point fixed communication experiments to communication applications in the moving state, and terahertz beam reconfigurable technology empowers multi-beam communication systems to provide support for terahertz dynamic communication. This paper introduces the research progress of phased array, meta-surface and other multibeam antennas in terahertz bands. The beam reconfiguration schemes and technical routes of terahertz dynamic communication are sorted out. The basic composition and key technologies of each scheme are analyzed. By discussing the advantages and disadvantages of each technical route, the development blueprint of terahertz dynamic communication system covering low frequency to high frequency is described. Multibeam technology will further accelerate the evolution of terahertz communication to flexible and changeable networking communication forms, and provide a technical foundation for the commercial application of 6G terahertz communication.

Abstract:

Terahertz Radio Frequency(RF) devices and communication systems typically exhibit operating bandwidths ranging from several GHz to tens of GHz, with substantial variations in operating characteristics across the band, presenting numerous challenges for performance testing. To address this, this paper proposes an automated measurement method for the terahertz band and designs a versatile automated test system capable of meeting diverse testing requirements, including terahertz RF device and link testing, signal processing algorithm testing, long-distance terahertz channel measurement, and terahertz antenna far-field testing. Measurement results demonstrate that the system can efficiently and accurately complete these various terahertz band testing tasks, not only improving testing efficiency but also providing reliable data support for related research and applications.

Abstract:

In response to the issues of functional coupling and low performance in traditional radar digital simulation platforms, an innovative approach has been proposed by integrating the concepts of object-oriented programming and component reuse. This approach introduces a component-based radar simulation architecture. By abstracting the various functions of the radar digital simulation system into independent components and implementing loose coupling communication through a signal-slot mechanism, the components are made mutually independent, thereby enhancing the reusability among them. Simulation verification has demonstrated that this component-based radar digital simulation platform operates accurately, displays normally, and possesses excellent adaptability and scalability. It is capable of meeting diverse simulation requirements and offers a new solution for radar system development.

Abstract:

Global Navigation Satellite Systems(GNSS) have been widely applied in mass consumer applications, mechanical control, maritime and aviation navigation, and disaster relief. However, due to the inherent weakness of navigation signals and the open user interface of GNSS, GNSS is highly vulnerable to spoofing attacks. Signal Quality Monitoring(SQM) technology offers a simple yet proven approach for detecting GNSS spoofing attacks. Nevertheless, traditional SQM algorithms are vulnerable to environmental factors, making it difficult to simultaneously satisfy the basic requirements of detection accuracy and timeliness. This paper proposes a spoofing detection algorithm based on the sum of absolute values from the in-phase(I) and quadrature(Q) branches. The implementation logic is simple and requires only minor software modifications to GNSS receivers. Experimental analysis using the spoofing signal dataset from the University of Texas at Austin(TEXBAT) demonstrates that, compared with conventional SQM algorithms, the proposed algorithm achieves faster detection speed and superior performance in detecting spoofing attacks.

Abstract:

In an electromagnetic countermeasure environment, communication behavior recognition is a crucial component of signal mining and utilization in electromagnetic space. Under non-cooperative conditions where prior information is difficult to obtain, acquiring electronic intelligence requires performing signal feature analysis on reconnaissance-acquired communication data and conducting communication behavior recognition. Based on extensive analysis of domestic and foreign literatures, this paper summarizes the definitions and classifications of communication behavior oriented toward non-cooperative wireless networks, introduces the concept and primary approaches of communication behavior recognition, and categorizes various existing implementation methods along with their characteristics. Finally, it concludes the main problems and challenges in current communication behavior recognition research and prospects potential future development directions for this technology.

Abstract:

To realize low-profile dual-polarized broadside radiation, a 1×8 dual-polarized low-profile slot antenna array fed by Substrate-Integrated Coaxial Line(SICL) is proposed. Unlike conventional dual-polarized arrays in which two independent feeding networks are vertically stacked, the radiating elements and the feeding network of the proposed design are arranged in the same layer, drastically reducing the overall profile. Measured results show that the array achieves a -10 dB impedance bandwidth in 25.8~27.4 GHz and an isolation higher than 20 dB. Benefiting from its simple feeding topology, low profile, and low fabrication cost, the proposed approach is highly attractive for future large-scale, high-gain, dual-polarized millimeter-wave applications.

Abstract:

To address the issue of narrow bandwidth in existing Multiple-Input Multiple-Output(MIMO) microstrip antennas, a compact broadband high-isolation MIMO microstrip antenna and array design is proposed. By introducing cross-type capacitive fences, open slots, and shorting vias, the isolation between ports is gradually enhanced. To validate this concept, a 1×2 microstrip antenna and a 2×2 array were fabricated and measured. The measured impedance bandwidth of the 2×2 array is 44.9%, with an isolation better than 21.8 dB, showing good consistency between the measured and simulated results. Based on the 2×2 array, the applicability of the proposed decoupling structure in large-scale arrays was further verified. Simulation results indicate that the impedance bandwidth of a 2×6 array is 43.5%, with an isolation of at least 20 dB within the operating bandwidth. Therefore, the proposed decoupling solution has broad application prospects in broadband high-isolation MIMO applications and antenna arrays.

Abstract:

To address the difficulty in predicting the Passive Intermodulation(PIM) of waveguide flange connections caused by micro-contact randomness, the fluctuations in both PIM and DC contact resistance at these joints are investigated. Experimental results demonstrate that, upon repeated connections, both PIM and DC contact resistance exhibit stochastic variations; moreover, the PIM level generally decreases as the DC contact resistance diminishes. To uncover the origins of these fluctuations, a Monte Carlo model for PIM at waveguide flanges is developed based on existing theories of PIM in electrical contacts. The numerical results agree well with experimental data, theoretically confirming that the random distribution of contact pressure during successive connections is a primary source of PIM variability in waveguide flange joints.

Abstract:

Transmission lines are often employed in complex metal shielded cavities, where numerical algorithm-based simulations are memory-intensive and computationally inefficient. This paper proposes a novel method for simulating the electromagnetic transient response of transmission line load coupling problems, which combines an improved Locally One-Dimensional Finite-Difference Time-Domain(LOD-FDTD) method with Modified Nodal Analysis(MNA) to more efficiently and accurately solve field-line-circuit electromagnetic problems at fine structural gaps. Gaps and cables are treated as electromagnetic structures, and the improved LOD-FDTD method is employed to solve the field distribution; based on the circuit substitution principle, MNA is employed to analyze the port voltages and currents of circuit modules, thereby completing the hybrid calculation of transient electromagnetic response for the entire field-line-circuit coupling problem. Simulation results demonstrate that, compared to other analysis methods, the proposed approach substantially enhances computational efficiency while maintaining reasonable numerical accuracy.

Abstract:

To address the challenges of privacy protection in recognizing unsafe behaviors such as falls and low cross-environment recognition rates, this paper proposes a behavior recognition framework, Single-antenna Cross-environment Stable Human Activity Feature Extraction and Recognition Framework (SSRF), based on Channel State Information(CSI), optimized from the existing ReWiS model. By collecting data on five types of elderly behaviors(such as falls, no action, etc.) from different environments, the CSI signals are normalized, followed by Singular Value Decomposition(SVD) and Pearson correlation coefficient calculation to generate labeled CSI data samples, which are then fed into the ProtoNet model for classification. Compared to ReWiS, SSRF significantly reduces the number of parameters(from 111 936 to 37 392) and accelerates both training and testing speed, with total training time reduced from 33.12 s to 26.8 s, and per-sample testing time reduced from 0.000 149 s to 0.000 104 s. In the four-category task of a public dataset and the five-category task of a custom dataset, SSRF achieves average cross-environment recognition accuracies of 89% and 85%, respectively, with 95% accuracy for fall detection. Experimental results show that SSRF maintains high generalization performance while significantly improving the efficiency.

Abstract:

A reduced-dimension Propagation Method(PM) based algorithm is proposed for central Direction-Of-Arrival(DOA) estimation of coherent distributed sources. Based on the Generalized Array Manifold(GAM) model, the central DOA can be decoupled from the original array manifold, achieving separation from the angular spread. To avoid eigenvalue decomposition of the sample covariance matrix, a propagation operator matrix is computed in the orthogonal space of the generalized array steering vectors to construct the objective function. With the introduced dimensionality reduction technique, the proposed algorithm only requires a one-dimensional spectral peak search to determine the central DOA of the sources, which significantly reduces the computational complexity. Additionally, the Cramér-Rao lower Bound(CRB) for this scenario is derived in detail to provide a benchmark for the estimation performance of the algorithm. Performance analysis and numerical simulation results demonstrate that the proposed algorithm maintains excellent angle estimation performance while reducing complexity.

Abstract:

For individual radiation source identification technology using deep neural networks, network depth is continuously increased to achieve good recognition performance, resulting in an explosion of model parameters and computational complexity, which makes deployment difficult on resource-constrained edge devices. To address this, this paper proposes a network architecture called ODCNet(One-Dimensional Depthwise Separable Convolution Network) based on one-dimensional depthwise separable convolution and one-dimensional convolutional block attention modules. By combining depthwise and pointwise convolutions, one-dimensional depthwise separable convolution effectively reduces model parameters and computational complexity. The lightweight one-dimensional convolutional block attention module can effectively enhance model performance and ensure recognition capability. Experimental results show that ODCNet's recognition performance is comparable to MobileNet V3, while its parameters are only 11.27% of MobileNet V3's, its computational complexity is 17.49% of MobileNet V3's, and its inference time is reduced to 50% of MobileNet V3's.

Abstract:

The rapid development of mobile communication technology has generated abundant unlabeled radio source signals. To fully utilize unlabeled data, this paper proposes an Independence Criterion-based Unsupervised Domain Adaptation(ICUDA) method for specific emitter identification. The independence criterion is employed to measure the similarity between the source domain and the target domain, and combined with an improved convolutional neural network to transfer knowledge from the source domain to the target domain, thereby helping improve the classification performance of the target domain that contains only unlabeled data. Under seven transfer scenarios constructed based on Software-Defined Radio(SDR) dataset collected in a laboratory environment, compared with baseline methods and three unsupervised domain adaptation methods, the proposed method achieves the best classification performance in the target domain across all scenarios, with an average recognition accuracy of 84.2%, demonstrating that the proposed method can extract features with good inter-class separability and intra-class compactness on the target domain, effectively reducing the target domain's dependence on high-quality labeled data.

Abstract:

Effective choice of the solution is essential to achieve a real-time, bi-directional(full- duplex) communication of the smart grid. The Power Line Carrier(PLC) technology provides a low-cost solution, which suits China's own national conditions. In this paper, the advantages of OFDM PLC modulation technology are introduced. A PLC module of system model is established through the analysis of the input impedance under the low-voltage power line channel. The high-speed PLC module based on low-voltage Power Line is also designed according to the studies of power line channel. The results show that the design of the PLC module has featured high receiving sensitivity and anti-noise ability.

Abstract:

With the development of Internet applications, users’ demand for bandwidth is soaring sharply. Meanwhile，along with the development of broadband access technology, the endpoint can also adopt multiple network accesses. But due to one-way communication of traditional Transmission Control Protocol(TCP)，the waste of resources will exist. To this end，IETF has specifically proposed Multi-Path TCP(MPTCP) to implement TCP multiplexing，thereby enhancing the efficiency and robustness. This paper gives a review of the IETF’s research on MPTCP，including MPTCP architecture, routing and congestion control, aiming to provide a reference for deeply studying.

Abstract:

Traditional methods and instruments are not able to measure the true Root Mean Square(RMS) of distortion sine wave or non-sine signal accurately. This article introduces a method to measure the true RMS of any high frequency signal by using the true RMS measurement IC，AD536A，designed by AD corporation. The paper analyses the difference between the RMS measured by the average measure method and the true RMS in theory. It explains the disadvantages of current RMS measure method，and presents the design of true RMS measure circuit. The experiment results prove that the proposed method and circuit can measure the true RMS of any high frequency signal accurately.

Abstract:

Terahertz(THz) optoelectronics has promoted the development of the THz generation, transparent control, and detection methods，and hastened many devices in the past decades. Especially, THz metamaterials and metasurfaces will exhibit extraordinary electromagnetic response when the subwavelength scale metal structure is excited by the THz illumination. Therefore, they have been applied to the devices such as wave beam shaper, waveguide, and modulator etc. The THz metamaterials and metasurfaces also show the potential applications in the research fields such as sensors, communications, and radars. In this paper, the works about the spectrum and wavefront modulation with THz metadevices carried out in our group are summarized. The basic theory and corresponding experiment results for different devices are introduced. It is expected these works can pave the avenue of the application of the THz metadevices.

Abstract:

Aiming at the problems in existing underground personnel positioning systems, an assisted positioning method based on pedestrian dead reckoning is proposed. Low-cost Inertial Measurement Unit(IMU) and magnetometer are employed to constitute a stable Attitude Heading Reference System (AHRS). The theory of inertial navigation is utilized, an algorithm for step detection is described, and Zero velocity Update(ZUPT) is adopted for velocity and position estimation to compose a pedestrian dead reckoning system. An experiment is performed in the corridor of a laboratory building to emulate the underground mine road environment. The experimental results demonstrate that the dead reckoning performs well and this method is an effective complement to existing underground positioning by improving the positioning accuracy.

Abstract:

The requirements for micro stress measurement of strain gauge are high precision，high linearity，high stability and high gain. One kind of differential amplifier circuit with excellent performance was designed. Some skillful techniques were adopted to avoid common voltage in the circuit and to reduce the temperature drift. The gain linearity is about 0.01%，and its Common-Mode Rejection Ratio(CMRR) is about 129 dB under work conditions.

Abstract:

The background requirements of the fuze antenna in terahertz spectrum as well as its advantages and disadvantages are introduced. The working principles and application characteristics of dielectric lens antenna in terahertz frequency are analyzed in order to implement the terahertz fuze antenna. The longitudinal size of H plane horn antenna can be reduced effectively by using fuze antenna formed by an H plane horn with dielectric lens antenna. The terahertz fuze antenna with different beam angles is achieved by focal technology of lens. The feasibility of the technology solution is verified through simulation.

Abstract:

According to the requirements of safe, simple and nondestructive radiation effect investigation of semiconductor devices, the method of laser simulation was proposed and greatly promoted. Compared with large-scale facilities, laser simulation has various unique advantages. It helps understand the ionization radiation effect in depth and is an effective low-cost, table-top supplement for the hardness assurance. Its research shows great significance for radiation effect study in both theory and practice. In this paper, the basic principles of the interactions of γ and laser with semiconductor devices are firstly presented. Then the physical basics and characteristics of laser simulation are given, with the research progress review followed. The existing problems of current research are deeply discussed providing with feasible research approaches. In the end, necessary research contents in the future are proposed.

Abstract:

Ultra-wideband(UWB) communication shows its advantages of fast data transfer(100 Mb/s or above) in a relatively short distance(typically below 10 m) with relatively weak power consumption (energy spectrum below -41.3 dBm/MHz). Integrated with Multiple Input Multiple Output(MIMO) technology, channel capacity could be further enhanced. As a critical link in the ultrawideband communication，UWB antenna needs extra efforts in design optimization to boost the performance of the whole system. UWB antenna is defined as the antenna whose bandwidth exceeds 500 MHz or relative bandwidth greater than 20%. This paper takes the most representative Vivaldi antenna as a show case for multi-objective optimization design with statistical methods. The optimized miniaturized antenna(sized130 mm×100 mm) shows a -10 dB bandwidth of 2.4 GHz. The design method provides guidance in common wideband，multi-parameter antenna design.

Abstract:

The design of code tracking loop is a key sector of the realization of noncoherent spectrum spread receiver. In order to realize the code tracking in noncoherent spectrum spread receiver, an energy-normalization digital delay-locked loop was designed, the structure of the loop and the calculating procedure of loop parameters were introduced. The characteristic of noncoherent spectrum spread was analyzed first，and then the key point of the loop design was pointed out. Based on this, the design and realization methods of code loop discriminator, loop filter, early and lag code generator were expatiated. A set of specific loop parameters were introduced as well. Modelsim simulation results and FPGA actual measured data prove the precise code tracking ability of the design.

Abstract:

Radio Frequency IDentification(RFID) series Radio Frequency(RF) card has been applied widely because of its stability，reliability and easy operation features. Aiming at multiple protocols，such as ISO14443 protocol，ISO15693 protocol and Tag-it protocol，this study proposed a new type of circuit design based on Advanced RISC Machine(ARM) for the RFID series RF card reader. The data stream encryption was implemented by using peripheral device in the operation. The system composition，working principle and work flow were introduced. Then，the detailed circuit design of the RF network and encryption hardware were presented，and the test and analysis for the design were performed. The results showed that the circuit could accurately read, write and encrypt various types of card within effective range.

Abstract:

The application of CORDIC(COordinate Rotation DIgital Computing) arithmetic in solving transcendental function has become popular in modern engineering. A brief introduction of CORDIC arithmetic was given in this study. Taking the hyperbolic sine and cosine functions as examples, the method of realizing the arithmetic in FPGA was presented and simulated on ISE(Integrated Software Environment) platform. The result showed this arithmetic was of good precision and instantaneity because of using pipeline. This arithmetic has great practical value in some applications. In addition, a curve of the relationship between the iterative number and the error obtained by the Matlab simulation of the arithmetic can help designers planning the number of iterations for practical applications.

Abstract:

The implementation of TCP/IP protocol stack on TM320DM642 platform could provide technological support for the application of multimedia embedded systems to networks. Both the function of TM320DM642 chip and the hierarchical structure of LWIP(Light Weight Internet Protocol) were analyzed. Network communications for TM320DM642 systems were implemented by the transplantation of LWIP, not by a solution scheme of NDK(Network Developer’s Kit). Testing examples verified the effectiveness of the LWIP transplanted method.

Abstract:

This article introduces a new type of high speed，multi-modulated digital modulator with adjustable center frequency and bit rate features. It can realize the Quadrature Phase Shift Keying(QPSK) and 16QAM(Quadrature Amplitude Modulation) with 80 MHz center frequency and 7.936 5 MHz bandwidth. The general-purpose modulation arithmetic based on software radio，symbol mapping and the realization of pulse shaping filter are discussed. The measuring results demonstrate that the modulation scheme meets the requirements of practicability and general utilization.

Abstract:

High-speed data acquisition system is an important component in modern radar signal processing. A design of high-speed data acquisition system based on band-pass sampling was presented and applied to the signal processing of wideband receiver. The Virtex Series FPGA was used as the main platform to control the high-speed ADC08D1000 for completing data acquisition, transmission，storage and signal processing. High-speed First Input First Output(FIFOs) were selected as the storage devices to implement data rate conversion. The system realized the software and hardware design，and test results verified the feasibility of the solution.

Abstract:

The Spatial Light Modulation(SLM) technology has been widely applied to the fields of threshold switch, high speed optical interconnection and optical logic operations, which demands good performance on the real-time and fast optical signal addressing. Compared with Electro-Addressing SLM(EA-SLM), Optically-Addressing SLM(OA-SLM) shows great advantages of fast speed and high resolution by parallel addressing. Nevertheless, how to achieve fast and stable optically addressing is the key point in practice. Based on ZnO thin film as a photoconductive layer, Liquid Crystal OASLM(LC-OASLM) is designed and fabricated; the modulation of the readout light intensity and phase distribution in the two-dimensional space is achieved effectively.

Abstract:

The corresponding solutions are proposed to tackle with the disadvantages of conventional oilfield Geographic Information System(GIS), including inconvenience of Client/Server(C/S) mode operation and maintenance, being unable to perform real-time online Point of Interest(POI) rendering, being incapable of segmentation and location according to regions, etc. An oilfield information query system of Browser/Serve(B/S) framework based on AJAX+JSON+HTML5 is designed and implemented. Experimental results show that the POI real-time rendering and regional segmentation improve on their interactivities, and the experiences of users are enriched, which meets the actual requirements of oilfield development. This work has paved the way for the development of diversified network services.

Abstract:

A detector can achieve quick response when it is much smaller than the wavelength of the source signal in THz wave band at the expense of signal coupling capability．Therefore, an antenna is applied to collect signals in order to enhance the signal coupling capability of the detector．The properties of antenna determine the frequency response band，the sensitivity and other parameters of the detector directly. A planar-integrated antenna is adopted for signal acquisition in the Nb5N6 microbolometer detector, which is fabricated by lithography，lift-off and other processes of micro-fabrication. The Nb5N6 microbolometer is placed in the center of the planar antenna. Aiming for the center frequency of 0.32 THz, a special capacitive coupling design is proposed to improve the signal coupling capability．

Abstract:

A double gate setting with priority of Doppler velocity and the Extended Kalman Filter(EKF) based Multiple Hypothesis Tracking(MHT) algorithm are proposed in order to realize Multiple Targets Tracking(MTT) in High Frequency(HF) ground-wave radar, and to effectively improve the performance of MTT by using the Doppler measurement. In the EKF based MHT, parameters obtained in the EKF are adopted directly to calculate the probability of each hypothesis. A simulation scene is built, and the EKF based MHT algorithm is compared with the one which assumes that the Doppler measurement is independent from the radius measurement. Simulation results show that the double gate setting helps induce number of clutter, and the EKF-based MHT algorithm is better than the other one under dense environments of HF ground-wave radar with stronger track-catching and false-alarm-filtering ability and higher efficiency.

Abstract:

The single-channel blind separation of GMSK(Gaussian Minimum Shift Keying) mixing signals is researched. The GMSK mixing signals can not be separated by the Per-Survivor Processing (PSP) algorithm directly, therefore, linear approximation processing of the GMSK signal is considered, which enables GMSK signal to be separated by the PSP algorithm. This algorithm separates the GMSK mixing signals by maximum likelihood estimation in the joint space of the symbol sequential and the channel parameters, reserves the best path and outputs the symbol pairs to get the separated signals. Simulation results show that the bit error rate performance produced by the PSP algorithm on separating the GMSK mixing signals is slightly better than that produced by the particle filtering algorithm; and the complexity of the proposed PSP algorithm is much smaller.

Abstract:

A new usage of Hough Transform is introduced in this paper.Firstly,the position and scope of the license plate is located and the image that contains the license plate is picked up.Then, a two-stage Hough transform algorithm is applied to the image to cal

Abstract:

A forward secure strong proxy signature scheme is proposed on the basis of the proxy signature schemes and forward secure schemes.The security of the proposed scheme relies on the difficulty of solving discrete logarithm problems and the difficulty of com

Abstract:

Based on three generally accepted basic hypotheses, the definition of environmental factor and restricting conditions of constant failure mechanism are discussed.The research status and common study methods of environmental factor are reviewed. Finally, a

Abstract:

For completing the scheme of hard target smart fuze, several factors influencing the outputting acceleration of the high-G accelerometer such as target material, impact angle, impact velocity, the fixed position of accelerometer, carry plane etc., are put

Abstract:

Blind source separation (BSS) is a recently developed methodology used to separate unknown source signals from their mixtures. It has been applied to many fields widely and effectively. The theory and two types of implementation methods-independent compon