Abstract:

In ground communication systems, microwave components of the base station are exposed in air for a period of time, usually influenced by temperatures, humidity, pollution and other factors. The original clean surface of the components is oxidized and contaminated, leading to poor contact and Passive Intermodulation(PIM), which interferes with the communication system. Therefore, PIM is inevitable in ground mobile communication system. In the satellite communication system, due to the long communication distance and platform limitation, the common transceiver mode should be adopted. As the receiver sensitivity increases, the requirements on PIM indexes are more strict. PIM is one of the key problems for realizing the high reliability of system. The characteristics and research progress of PIM interference in ground mobile communication and satellite microwave components are introduced, which can provide a reference for PIM research.

Abstract:

Passive Intermodulation(PIM) is one of the key reliability problems of the microwave circuits. With the development of microwave system integration and miniaturization, the microstrip circuits are widely used in the industry and studied by the researchers. Therefore, it has great value to investigate the physical mechanisms, the evaluation methods, and the suppression technologies of the PIM interference in the microstrip circuits. The nonlinearities in the microstrip circuits are usually distributed, which are usually different from that of the cavity based microwave devices, and they are also associated with the substrate materials, the fabrication processes and the device structures. All these make it difficult to solve the PIM problems in the microstrip circuits. Though more and more PIM investigations for the mircostrip circuits have been reported in recent years, the practical high-quality circuit-design still faces challenge. In this paper, we review the recent developments about the PIM phenomenon in the microstrip circuits including the nonlinearity mechanisms, the modeling and simulation methods, and the measurement technologies, which could provide comprehensive guidance for the future study of the PIM problems in the microstrip circuits.

Abstract:

As an important electrical connector, the reliability of spring electrical connection directly affects the electrical performance of the device. It is important to study the regularity and influencing factors of spring electrical connection for improving equipment performance and saving cost. In this paper, through software simulation and experimental measurements, the rule is tested that the contact resistance decreases with the decrease of the resistivity of the contact metal surface material and decreases with the increase of the applied force when the electrical connection parts represented by the spring are under weak external force(<2N). Through the analysis and calculation of mechanical contact theory, it is verified that the contact resistance is affected by the resistivity and external force of the material. The mechanism of contact resistance of the projectile is clearly explained, and the relationship between contact resistance of the projectile and different contact interfaces can be more accurately judged.

Abstract:

A method is proposed to measure electrical contact Passive Intermodulation(PIM) based on a slot waveguide, which is separable and can simultaneously measure contact resistance and PIM. On this basis, the statistical behavior of metal contact PIM is investigated. Firstly, it is determined that the existence of oxide film on the surface of Device Under Test(DUT) with aluminum and silver coated aluminum, is the main reason for the producing of PIM, by characterizing the surface topography and analyzing the components. Secondly, the contact resistance(R_c) and its statistical regularities are obtained by repeating loading-unloading at some certain pressure with four-terminal sensing method. Finally, the relationship among contact resistance, PIM and contact pressure of aluminum alloy and silver coated aluminum alloy are measured by special designed slot waveguide measurement system. The experimental results show that, the contact resistance of the contact joint has the statistical characteristic under the certain pressure and its PIM value is also fluctuant. Both the contact resistance and PIM value decrease as the contact pressure increases and their fluctuant ranges decrease.

Abstract:

The Passive Intermodulation(PIM) value of the reflector's metal mesh, an important performance parameter of high-power spaceborne mesh antenna, is tested traditionally by the radiation method which requires a large size of metal mesh sample and has a low test efficiency. A 3-port PIM test method is proposed for the metal mesh, which is carried out by adopting a waveguide testing system based on the 3-port module. A PIM performance test system based on the 3-port module is constructed in order to verify the effectiveness of this test method. The PIM performance test is carried out on two metal mesh samples of the traditional type and the improved type, respectively. The test results show that the PIM performance of the improved metal mesh sample has been improved by 50 dB than that of the traditional mesh sample. This metal mesh's PIM test system bears the characteristics of high integration, stable performance, and high system construction efficiency. The test sample size for the proposed method is reduced to about 1/10 than that of the traditional method. The proposed 3-port PIM test method provides support for the rapid research of novel low-PIM-level metal meshes.

Abstract:

Wireless communication systems are increasingly developing towards high power and high sensitivity. The interference of Passive Intermodulation(PIM) on signal transmission is one of the difficult problems to be solved in the development of communication systems. Based on this, the mechanism of passive intermodulation is summarized in this paper. The research progress of passive intermodulation suppression technology from three aspects, such as reducing contact surface roughness, applying coating materials and optimizing device structure, are mainly reviewed. Moreover, the advantages and disadvantages of different suppression technologies are analyzed. Finally, the development trends of passive intermodulation suppression technology are prospected. This work aims to provide reference and guidance for relevant researchers.

Abstract:

In the context of rapid development of terahertz communication technology, the complex scattering property of wireless channel caused by building occlusion, bad weather and other reasons poses new challenges on secure and reliable data transmission. The confidentiality property of terahertz communication contains risks such as leakage and eavesdropping under the wide area of the communication network. Investigations on the feasibility of existing encryption and anti-eavesdropping methods in terahertz communication systems, promoting the innovation and application of physical layer security technology, and achieving stable and secure data transmission have become a valuably urgent topic. In this paper, from the perspective of secure communication, some of the existing physical layer encryption and anti-eavesdropping methods are presented and analyzed; their fusion applications and efficiencies in terahertz communication are summarized; and the trends on future development are expected.

Abstract:

The spectral characteristics of solid α-lactose are studied by using the attenuated total reflection Terahertz Time-Domain Spectroscopy(THz-TDS) technique. Firstly, the experiment is based on the traditional transmission spectroscopy technique, and two strong absorption peaks at 0.53 THz and 1.36 THz are obtained. In addition, taking two samples ofα-lactose with the doses of 1.8 mg+2.56 mg and 1.8 mg respectively the absorption lines are obtained by the attenuated total reflection THz-TDS system. Strong absorption peaks appear at 0.53 THz and 1.36 THz. Increasing the sample dose has no effect on the absorption intensity at 0.53 THz and 1.36 THz. Finally, taking two samples of α-lactose with the same doses, one is screened to 75 μm, and the other is not screened, the absorption lines are obtained by the attenuated total reflection THz-TDS system. Strong absorption peaks appear at 0.53 THz and 1.36 THz. When the particle size of the sample is reduced, the absorption intensity increases around 0.53 THz and 1.36 THz.

Abstract:

Micro-motion of helicopter blades forms the micro-Doppler effect, which is a kind of important characteristic and is extremely important for identifying different types of helicopters in the battlefield environment. Determining the micro-motion characteristics of helicopter rotor is the precondition for the identification. Because of the short wavelength and significant Doppler effect of terahertz radar, it is urgent to determine the fretting characteristics of the rotor target in terahertz band. Firstly, the propeller targets with even and odd blades are modeled. Then, the targets are simulated by using the radar in microwave band(3 GHz) and terahertz band(120 GHz, 220 GHz), and the Doppler frequency shift information is extracted from the characteristics of the target echo signal. Using Short Time Fourier Transform(STFT) in time-frequency analysis, the influence of the target and the radar parameters on the Doppler effect and the modulation relationship are contrasted. The simulation results show that the micro-Doppler effect in Terahertz band is more significantly enhanced than that in microwave band, and the Doppler curve is clearer and more details of the blades can be observed under the condition of the same rotation speed, angle of view and blade length. Using terahertz radar to extract micro-Doppler information can provide significant features for helicopter target recognition.

Abstract:

The evaluation of System of Systems(SoS) contribution rate is an important index for the effectiveness assessment of electronic information equipment SoS. Taking a typical electronic information equipment for example, the essence of electronic information equipment SoS is investigated, and its complexity such as openness and dynamic property are analyzed.It is pointed out that the contribution rate of electronic equipment SoS should be evaluated by systematic theory. Based on the meta-synthesis method, the integrated method process of contribution rate evaluation of typical electronic information equipment SoS is studied by taking radar equipment as an example, and three important steps of the process are given, including the qualitative integrated judgment and understanding of the connotation, essential characteristics and function mode of contribution rate of electronic information equipment SoS, the indexes selection and evaluation combined with qualitative and quantitative evaluation of SoS contribution rate, as well as the comprehensive integration methodology from qualitative to quantitative analysis and verification of system contribution rate evaluation indexes, which provides reference for contribution rate test and evaluation of electronic equipment test system.

Abstract:

Aiming at the nonuniform weighting for covariance lags in virtual array interpolation, the covariance matrix reconstruction of the coprime array is modeled as the low-rank matrix completion and atomic norm reconstruction. A novel covariance matrix reconstruction algorithm based on atomic norm for coprime array is proposed. Firstly, the Generalized Augmentation Approach(GAA) is utilized to obtain a partial covariance matrix of the coprime array. Then the partial covariance matrix is completed with the truncated mean singular value threshold method and reconstructed through the atomic norm minimization. A robust positive definite Toeplitz covariance matrix is accomplished. The proposed algorithm makes full use of the information contained in the coprime array to improve the stability of Direction of Arrival(DOA) estimation algorithm and reduce the computational complexity.

Abstract:

In All-Digital Transmitter(ADTx) system, Radio Frequency Pulse Width Modulation(RF-PWM) encodes the amplitude and phase information of baseband modulation signal into the width and position of output pulse. Due to the non-ideal characteristics of digital signal processing devices, the rising edge and falling edge of the clock signal have jitter errors, which affects the output signal quality of RF-PWM. Based on three RF-PWM implementation schemes, the distortion term caused by timing jitter is determined by formula derivation, and the mathematical analytical expressions of the noise floor of different schemes' output pulse signals under the influence of timing jitter are given. Finally, Matlab is employed to simulate and verify the fundamental, odd harmonic and noise floor of different schemes under the condition of timing jitter, which proves the correctness of theoretical derivation. At the same time, the Error Vector Magnitude(EVM) and Adjacent Channel Power Ratio(ACPR) of signal are simulated, and the influence of timing jitter on the performance of signal in-band and out-of-band is analyzed. The results show that the nonlinear distortion caused by timing jitter is mainly reflected in the improvement of noise floor. For different RF-PWM implementation schemes, the influence characteristics of timing jitter are different, among which the five-level scheme has a restraining effect on timing jitter, and it increases with the increase of time resolution.

Abstract:

A dual-feed circularly polarized patch antenna based on Substrate Integrated Coaxial Line(SICL) feed is proposed. Dual-feed point method is utilized to realize circular polarization. With the backed cavity, the antenna performance, for example, the bandwidth, the back lobe, the mutual coupling and the structure miniaturization, has been improved. Simulation results show that the antenna can achieve S₁₁<-10 dB(relative bandwidth is 28.8%@51 GHz) at 42.42~56.69 GHz, and the axial ratio is less than 3 dB and the maximum gain is 8.9 dBi at 45.26~48.08 GHz.

Abstract:

A Ku-band high gain eight-channel Transmitter and Receiver(T/R) module is discussed and fabricated with the advantages of highly integrated design of Low Temperature Co-fire Ceramic(LTCC) technologies. The module improves the transmit and receive gains of the component effectively by using bidirectional amplifier. By combining the silicon aluminum shell and the aluminum alloy heat dissipation teeth, the heat conduction ability of the module under continous wave emission conditions is improved greatly. A transmitting power level of 1 W, an emission gain greater than 45 dB, and a receiving gain greater than 29 dB, a receiving circuit noise less than 3.5 dB of the eight-channel T/R module are realized, with a size of 84 mm×48 mm×6 mm, and a low weight of 60 grams. The eight channels of the module have good consistency and stable performance. The module has a good engineering applicability value.

Abstract:

To address the problems of poor robustness and poor detection accuracy of multimodal remote sensing image saliency detection, this paper proposes a method based on the novel and efficient Multi-modal Edge aware Guidance Network(MEGNet), which mainly consists of a salient detection backbone network for multi-modal remote sensing images, a cross-modal feature sharing module and an edge aware guidance network. First of all, a Cross-modal Feature Sharing Module(CFSM) is used during feature extraction for remote sensing image pairs, which encourages different modalities to complement each other in the feature extraction process and suppresses the influence of defective feature data from different modalities. Secondly, based on the Edge Aware Guidance Network(EAGN), the effectiveness of edge features is detected through the edge map supervision module and the final salient detection map will have clear boundaries. Finally, experiments are carried out on three kinds of saliency objects detection remote sensing image datasets. The average Fβ, Mean Absolute Error(MAE) and Sm scores are 0.917 6, 0.009 5 and 0.919 9, respectively. The experimental results show that the proposed MEGNet is suitable for saliency detection in multi-modal scenes.

Abstract:

Multi-channel isolation transmission based on fragmentation of information data is one of the common methods to ensure the security of information transmission, but it lacks the theory of provable security and evaluation methods. A multi-channel fragmentation transmission system is formally defined firstly, including data encryption, fragmentation multi-channel transmission and recombination functions. Then from the data leakage probability analysis in the process of multi-channel transmission, the provable security level of multi-channel fragmentation transmission technology is defined. A set of security level evaluation methods for multi-channel data fragmentation transmission is established to verify the effectiveness of the security level evaluation method from the theoretical point of view. This paper provides theoretical guidance for the realization of multi-channel data fragmentation transmission technology and guidelines for the security evaluation of multi-channel data fragmentation transmission system. The proposed method can also be applied to the security analysis of data fragmentation storage and transmission.

Abstract:

Micro-blog text data is high-dimensional, bearing the obvious features of synonymy and polysemy. Traditional topic detection method based on Vector Space Model(VSM) combined with K-means has some problems such as low accuracy, complex calculation, and being difficult to determine the center of clustering. A Relevance Vector Machine(RVM) optimized VSM method is proposed to realize the text vectorization. Firstly, the dimension of VSM feature vector is reduced automatically by using the adaptive feature selection ability of RVM, and then Principal Component Analysis(PCA) is applied to determine the cluster center of K-means clustering algorithm. K-means algorithm is employed to get the clustering results. Finally, according to the number of micro-blog forwarding and comments, the topic with the largest heat index is the current hot topic. The results show that compared with two traditional methods, the accuracy of the proposed method is improved by 7.3% and 1.1%, and the real-time performance is improved by 45% and 53%, respectively.

Abstract:

It is difficult to distinguish the spaceborne single-photon laser echo signal mixed with the noise. A two-step method for denoising spaceborne single-photon data based on statistical histogram is proposed. In order to eliminate noisy photons in the spaceborne single-photon echo data, a small window histogram method along the track is used for coarse denoising, and then a distance square statistical histogram method is used for fine denoising. The echo photon data of the Advanced Topographic Laser Altimeter System(ATLAS) spaceborne single photon lidar under three typical conditions of strong and weak beam, day and night, flat ground and mountain are selected as experimental data. Combined with the official results of ATLAS and based on the confusion matrix, the de-noising accuracy is calculated. Experimental results show that the denoising accuracy of strong beam data is 98.86%, and that of weak beam data is 96.94%; the denoising accuracy of night data is 99.02%, and that of daytime data is 98.86%; the denoising accuracy of mountain data is 96.28%, and that of flat data is 96.94%. The results show that the proposed method is suitable for spaceborne single photon data denoising under above three typical conditions.

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:

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:

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:

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:

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:

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 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:

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:

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:

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:

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 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:

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 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:

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 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:

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:

Wavelet denoising is an important application of wavelet analysis in engineering.The keys of wavelet denoising,namely how to select threshold and how to utilize the threshold to dispose wavelet coefficients,are introduced.Via the noised simulated signal e

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