Fan, Xiangrui; Lin, Jingyong; Liu, Jiarun; Zhou, Chunmei
Data link is the key information system for the cooperation of weapons, single physical layer anti-jamming technology has been unable to meet its requirements. High dynamic precision-guided weapon nodes like missiles, anti-jamming design of data link system need to have stronger pertinence and effectiveness: the best anti-jamming communication mode can be selected intelligently in combat environment, in real time, guarantee the continuity of communication. We discuss an anti-jamming intelligent networking technology of data link based on interference awareness, put forward a model of intelligent anti-jamming system, and introduces the cognitive node protocol stack model and intelligent anti-jamming method, in order to improve the data chain of intelligent anti-jamming ability.
Small satellite communication has an increasingly important position among the wireless communications due to the advantages of low cost and high technology. However, in view of the case that its relay station stays outside the earth, its uplink may face interference from malicious signal frequently. Here this paper classified enumerates existing interferences, and proposes channel signals as main interference by comparison. Based on a basic digital communication process, then this paper discusses the possible anti - jamming techniques that commonly be realized at all stages in diverse processes, and comes to the conclusion that regarding the spread spectrum technology and antenna anti-jamming technology as fundamental direction of future development. This work provides possible thought for the design of new small satellite communication system with the coexistence of multi - technologies. This basic popular science can be consulted for people interested in small satellite communication.
Jyoti, Vishav; Kaler, R. S.
In this paper, we propose a novel anti-jamming technique for optical code division multiple access (OCDMA) network through four wave mixing (FWM) in semiconductor optical amplifier (SOA) based wavelength converter. OCDMA signal can be easily jammed with high power jamming signal. It is shown that wavelength conversion through four wave mixing in SOA has improved capability of jamming resistance. It is observed that jammer has no effect on OCDMA network even at high jamming powers by using the proposed technique.
Li, Yang-Jun; Lian, Su-Jie; Shi, Jia; Guo, Ya-Fei; Wang, Gao
In order to improve anti-jamming capability of Michelson interferometer system, replace the traditional structure of the moving mirror scanning was replaced, an interference system based on electro-optic modulation of crystal refractive index was designed to achieve optical path scanning. The system modulated voltage signal on the variable refractive crystal, to generate cyclical changes, changed the refractive index to control optical path difference in the original optical path system. Using electronic scanning to replace of mechanical scanning, improved the system's noise immunity was improved. In the electro-optic modulation process, computed the maximum optical path difference of the system was computed, and analyzed of the crystal thickness and crystal diffraction efficiency of the modulation process were analyzed. The simulation experiment shows that, with the modulation voltage range increasing, the available range of the optical path is also increased, and the system spectrum resolving power will also increase accordingly. Meanwhile, in the modulation process set the modulation range was set to make the energy of diffraction energy losses less than 10% of the total energy, so as to ensure a better signal to noise ratio. Experimental results show that, as the modulation voltage changes, interference fringes occurred continuously moved. When the voltage is further increased, the nonlinear error appears. After non-linear error correction for the system, spectrum resolution reached to 7. 2 cm-1, slightly lower than the original system. But its anti-jamming capability is greatly enhanced, as in the absence of experimental platform for seismic conditions, conventional interferometer relative error is more than 20%, while the relative error of the system is less than 5%, in line with the design requirements. It was proved that the anti-jamming capability of the system was enhanced greatly, when the static electro-optical modulation was used.
Cui Jian Hua
Full Text Available Aiming at the problems existing in the attitude measurement using carrier phase of navigation signal in the jamming environment, an antenna array for anti-jamming attitude measurement is constructed. The antenna array is constructed by three circle array with core. An anti-jamming measurement method based on antenna array is proposed. This method uses array antenna to estimate the direction of arrival jamming signal though MUSIC algorithm. Then the adaptive nulling algorithm based on the linear constrained minimum variance algorithm is used to eliminate the jamming and hold the navigation signal. Finally, the double difference method is used to measure the attitude. The whole attitude information is obtained by the attitude measurement of the two baselines. Simulation has been made for eliminating the jamming with adaptive nulling algorithm. Comparison of the attitude measurement accuracy is also made by simulation. The results show that the algorithm we proposed can significantly inhibit the jamming and improve the accuracy of attitude measurement.
Full Text Available Serat optic merupakan media transmisi yang dapat menghantarkan informasi dalam bentuk cahaya. digunakannya cahaya sebagai media penghantaran informasi membuat media ini dapat menghantarkan informasi dengan kapasitas besar dalam waktu yang sangat singkat. Sehingga saat ini serat optic banyak digunakan dalam Telekomunikasi. jaringan serat optic ini harus disertai dengan teknik keamanan yang handal dalam proses transmisi informasinya, karena jika terjadi penyerangan dalam jaringan yang serat optic maka data yang akan diterima oleh receiver akan jauh berbeda dengan data yang dikirim transmitter. Sehingga hal ini sangat fatal jika informasi yang dikirimkan memiliki tingkat kerahasiaan yang sangat tinggi seperti informasi keamanan Negara. Adapun metode yang dapat digunakan dalam pengamanan jaringan serat optic adalah metode steganography dan metode anti-jamming. Dari percobaan yang telah dilakukan terlihat bahwa teknik steganography memiliki tingkat kehandalan yang lebih baik jika dibandingkan dengan metode anti-jamming dengan nilai BER untuk metode steganography adalah 1.91219e-077.
The Chernoff bound parameter, D, provides a performance measure for all coded communication systems. D can be used to determine upper-bounds on bit error probabilities (BEPs) of Viterbi decoded convolutional codes. The impact on BEP bounds of channel measurements that provide additional side information can also be evaluated with D. This memo documents the results of a Chernoff bound parameter evaluation in optimum partial-band noise jamming (OPBNJ) for both BPSK and DPSK modulation schemes. Hard and soft quantized receivers, with and without jammer side information (JSI), were examined. The results of this analysis indicate that JSI does improve decoding performance. However, a knowledge of jammer presence alone achieves a performance level comparable to soft decision decoding with perfect JSI. Furthermore, performance degradation due to the lack of JSI can be compensated for by increasing the number of levels of quantization. Therefore, an anti-jam system without JSI can be made to perform almost as well as a system with JSI.
Xu, Hailong; Cui, Xiaowei; Lu, Mingquan
Nowadays, software-defined radio (SDR) has become a common approach to evaluate new algorithms. However, in the field of Global Navigation Satellite System (GNSS) adaptive array anti-jamming, previous work has been limited due to the high computational power demanded by adaptive algorithms, and often lack flexibility and configurability. In this paper, the design and implementation of an SDR-based real-time testbed for GNSS adaptive array anti-jamming accelerated by a Graphics Processing Unit (GPU) are documented. This testbed highlights itself as a feature-rich and extendible platform with great flexibility and configurability, as well as high computational performance. Both Space-Time Adaptive Processing (STAP) and Space-Frequency Adaptive Processing (SFAP) are implemented with a wide range of parameters. Raw data from as many as eight antenna elements can be processed in real-time in either an adaptive nulling or beamforming mode. To fully take advantage of the parallelism resource provided by the GPU, a batched method in programming is proposed. Tests and experiments are conducted to evaluate both the computational and anti-jamming performance. This platform can be used for research and prototyping, as well as a real product in certain applications.
Xu, Hailong; Cui, Xiaowei; Lu, Mingquan
Nowadays, software-defined radio (SDR) has become a common approach to evaluate new algorithms. However, in the field of Global Navigation Satellite System (GNSS) adaptive array anti-jamming, previous work has been limited due to the high computational power demanded by adaptive algorithms, and often lack flexibility and configurability. In this paper, the design and implementation of an SDR-based real-time testbed for GNSS adaptive array anti-jamming accelerated by a Graphics Processing Unit (GPU) are documented. This testbed highlights itself as a feature-rich and extendible platform with great flexibility and configurability, as well as high computational performance. Both Space-Time Adaptive Processing (STAP) and Space-Frequency Adaptive Processing (SFAP) are implemented with a wide range of parameters. Raw data from as many as eight antenna elements can be processed in real-time in either an adaptive nulling or beamforming mode. To fully take advantage of the parallelism resource provided by the GPU, a batched method in programming is proposed. Tests and experiments are conducted to evaluate both the computational and anti-jamming performance. This platform can be used for research and prototyping, as well as a real product in certain applications. PMID:26978363
Full Text Available Nowadays, software-defined radio (SDR has become a common approach to evaluate new algorithms. However, in the field of Global Navigation Satellite System (GNSS adaptive array anti-jamming, previous work has been limited due to the high computational power demanded by adaptive algorithms, and often lack flexibility and configurability. In this paper, the design and implementation of an SDR-based real-time testbed for GNSS adaptive array anti-jamming accelerated by a Graphics Processing Unit (GPU are documented. This testbed highlights itself as a feature-rich and extendible platform with great flexibility and configurability, as well as high computational performance. Both Space-Time Adaptive Processing (STAP and Space-Frequency Adaptive Processing (SFAP are implemented with a wide range of parameters. Raw data from as many as eight antenna elements can be processed in real-time in either an adaptive nulling or beamforming mode. To fully take advantage of the parallelism resource provided by the GPU, a batched method in programming is proposed. Tests and experiments are conducted to evaluate both the computational and anti-jamming performance. This platform can be used for research and prototyping, as well as a real product in certain applications.
Seo, Jiwon; Chen, Yu-Hsuan; De Lorenzo, David S.; Lo, Sherman; Enge, Per; Akos, Dennis; Lee, Jiyun
Due to their weak received signal power, Global Positioning System (GPS) signals are vulnerable to radio frequency interference. Adaptive beam and null steering of the gain pattern of a GPS antenna array can significantly increase the resistance of GPS sensors to signal interference and jamming. Since adaptive array processing requires intensive computational power, beamsteering GPS receivers were usually implemented using hardware such as field-programmable gate arrays (FPGAs). However, a software implementation using general-purpose processors is much more desirable because of its flexibility and cost effectiveness. This paper presents a GPS software-defined radio (SDR) with adaptive beamsteering capability for anti-jam applications. The GPS SDR design is based on an optimized desktop parallel processing architecture using a quad-core Central Processing Unit (CPU) coupled with a new generation Graphics Processing Unit (GPU) having massively parallel processors. This GPS SDR demonstrates sufficient computational capability to support a four-element antenna array and future GPS L5 signal processing in real time. After providing the details of our design and optimization schemes for future GPU-based GPS SDR developments, the jamming resistance of our GPS SDR under synthetic wideband jamming is presented. Since the GPS SDR uses commercial-off-the-shelf hardware and processors, it can be easily adopted in civil GPS applications requiring anti-jam capabilities. PMID:22164116
Full Text Available Due to their weak received signal power, Global Positioning System (GPS signals are vulnerable to radio frequency interference. Adaptive beam and null steering of the gain pattern of a GPS antenna array can significantly increase the resistance of GPS sensors to signal interference and jamming. Since adaptive array processing requires intensive computational power, beamsteering GPS receivers were usually implemented using hardware such as field-programmable gate arrays (FPGAs. However, a software implementation using general-purpose processors is much more desirable because of its flexibility and cost effectiveness. This paper presents a GPS software-defined radio (SDR with adaptive beamsteering capability for anti-jam applications. The GPS SDR design is based on an optimized desktop parallel processing architecture using a quad-core Central Processing Unit (CPU coupled with a new generation Graphics Processing Unit (GPU having massively parallel processors. This GPS SDR demonstrates sufficient computational capability to support a four-element antenna array and future GPS L5 signal processing in real time. After providing the details of our design and optimization schemes for future GPU-based GPS SDR developments, the jamming resistance of our GPS SDR under synthetic wideband jamming is presented. Since the GPS SDR uses commercial-off-the-shelf hardware and processors, it can be easily adopted in civil GPS applications requiring anti-jam capabilities.
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KHANH PHAM BRETT J. DEBLONK, Ph.D. Program Manager Technical Advisor, Spacecraft Component Technology Branch //SIGNED...theory 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON Khanh Pham a. REPORT...Distribution Statement A: Approved for public release; distribution is unlimited. Acknowledgement The authors appreciate Dr. Khanh Pham for his support
Small Aperture Terminal ( VSAT Terminals). Interference is also attributed to the over-crowdedness of the frequency spectrum and the intense competition...User TTR Time-to-Rendezvous UHF Ultra High Frequency VSAT Very Small Aperture Terminal WRAN Wireless Regional Area Network
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National Aeronautics and Space Administration — MARK Resources proposes to develop a method for combining a set of distributed FRPAs into a network that provides high GPS anti-jam/interference capability. Like a...
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Chen, Zhenyu; Meng, Yan; Chen, Yanhong
This paper presents a technical scheme for the integrating of all types of strategic and tactical C4ISR systems through special satellite communication network and proposes information collection and distribution integrating networking scheme. The implementations of compatibility and interoperability of integrated system is described, and also anti-jamming features, covertness, and nuclear survivability are discussed.
Sun, Shou-jun; Wu, Kai; Wu, Xiao-Ming
This paper presents a wireless mobile monitoring system based on Bluetooth technology. This system realizes the remote mobile monitoring of multiple physiological parameters, and has the characters of easy use, low cost, good reliability and strong capability of anti-jamming.
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Full Text Available For digital model of brushless DC motor, simulation models can be built in MATLAB / Simulink. Simulation parameters are selected parameters according to the actual system. The conventional PID control algorithm produce large overshoot and oscillation, we use fuzzy logic PID algorithm to response quickly and back the system overshoot to steady state, the steady state has a higher precision, faster response speed, and bigger anti-jamming capability.
Adamy . 2.1 Reinforcement Learning A reinforcement learning (RL) or a Markov Decision Process ( MDP ) approach has been previously used in the...wireless sensor networks . To address time-varying jamming conditions, the authors formulated the anti-jamming problem of the sensor network as a MDP ...their work did not offer a jamming strategy; it offered a method of choosing the best jamming strategy from a given set. Wu et al., used a MDP
Full Text Available The study on radar polarization information acquisition and processing has currently been one important part of radar techniques. The development of the polarization theory is simply reviewed firstly. Subsequently, some key techniques which include polarization measurement, polarization anti-jamming, polarization recognition, imaging and parameters inversion using radar polarimetry are emphatically analyzed in this paper. The basic theories, the present states and the development trends of these key techniques are presented and some meaningful conclusions are derived.
Lin, Sen; Wang, Guanglong
A fuzzy PID control algorithm is studied based on improved particle swarm optimization (PSO) to perform Brushless DC (BLDC) motor control which has high accuracy, good anti-jamming capability and steady state accuracy compared with traditional PID control. The mathematical and simulation model is established for BLDC motor by simulink software, and the speed loop of the fuzzy PID controller is designed. The simulation results show that the fuzzy PID control algorithm based on PSO has higher stability, high control precision and faster dynamic response speed.
Kostarev, S. N.; Sereda, T. G.
The article is concerned with the problem of transmitting data from telemetric devices in order to provide automated systems for the electric drive control of oil-extracting equipment. The paper given discusses the possibility to use a logging cable as means of signal transfer. Simulation models of signaling and relay-contact circuits for monitoring critical drive parameters are under discussion. The authors suggest applying the operator ⊕ (excluding OR) to increase anti-jamming effects and to get a more reliable noise filter.
Su, Chengeng; Guo, Shuren; Zhou, Hongwei
CPM (continuous phase modulation) has been widely used in the field of satellite communication, which has high spectrum efficiency and constant envelope. This paper explores the applicability of CPM to satellite navigation. A SS-CPM (Spread-Spectrum CPM) modulation is investigated. The SS-CPM with tuned parameters can resemble the spectrum of Binary Offset Carrier (BOC) modulation and yields comparable performance in terms of tracking accuracy, multipath mitigation, anti-jamming, and compatibility. The BOC-like SS-CPM signal maintains the constant envelope at transmission and less out-band emission in radio determination satellite service (RDSS) band, which provides a reference modulation for COMPASS satellite navigation signal.
Li, Dairuo; Xu, Kai
In today's society, with the rapid development and extensive application of the information technology of the network central station and the integrated information system technology, information plays an important role in the military communication, mastering the information right to the competition Important role, how to protect one's own security, smooth access to and transmission of information, and to maximize the elimination of interference has become an important issue at home and abroad. QPSK modulation and its improved QPSK modulation as the mainstream signal modulation, the most widely used. In this paper, the principle of QPSK and QDPSK modulation and demodulation are introduced in this paper. Then, how to interfere with QPSK modulation signal is analyzed, and the interference of QPSK modulation signal is simulated by Matlab scripting program, which can be used in the next step. And to study the next step of anti-jamming measures provided the basis and preparatory work.
Full Text Available By comparison various control methods currently for permanent magnet brushless DC motor, on the basis of motor principle analysis, a current smallest and most real-time all-digital rare earth permanent magnet brushless DC motor control system is designed. The high-speed digital signal processor DSP2812 is applied as the main control unit. The fuzzy PID control algorithm is used to control rectifier regulator and speed, which the speed and current is double closed loop in the system. The principle of control system, control strategy and software is analyzed in this paper. The system has some features such as less overshoot, rapid response speed, good performance of anti-jamming, simple structure, high control precision, flexible in changing control policies and so on. Validity of the design is verified by prototype test.
Wang Yan; Jiao Hongling; He Shanhong; Pan Chao; Feng Deren; Che Wenquan; Xiong Ying
The effective electromagnetic pulse protection is studied in this paper, first the interference of electromagnetic pulse simulator path is analyzed, including the digital signal processor (DSP) and the discharge circuit of coupling interference and net electricity coupling interference. Using the structure optimization design, the hardware block reinforcement measurement and the setting of open software trap, and the watchdog anti-jamming measures, the interference test is completed such as the central processor core voltage of DSP, input/output (I/O) ports of DSP and the display screen. The experimental results show that the combination of hardware and software protection reinforcement technology is effective, and the interference pulse amplitude of DSP board I/O port and the kernel work voltage are reduced, and the interference duration is reduced from 2 μs to 400 ns. The interference pulse is effectively restrained. (authors)
Luo, Ruidan; Xu, Ying; Yuan, Hong
Navigation signal based on compound carrier (NSCC), has the flexible multi-carrier scheme and various scheme parameters configuration, which enables it to possess significant efficiency of navigation augmentation in terms of spectral efficiency, tracking accuracy, multipath mitigation capability and anti-jamming reduction compared with legacy navigation signals. Meanwhile, the typical scheme characteristics can provide auxiliary information for signal synchronism algorithm design. This paper, based on the characteristics of NSCC, proposed a kind of joint tracking method utilizing Weighted Least Square (WLS) algorithm. In this method, the LS algorithm is employed to jointly estimate each sub-carrier frequency shift with the frequency-Doppler linear relationship, by utilizing the known sub-carrier frequency. Besides, the weighting matrix is set adaptively according to the sub-carrier power to ensure the estimation accuracy. Both the theory analysis and simulation results illustrate that the tracking accuracy and sensitivity of this method outperforms the single-carrier algorithm with lower SNR.
Full Text Available The approach of using Magnetic Angular Rate Gravity (MARG sensor for the current multi-sensor based pedestrian navigation algorithm magnetometers is susceptible to the external magnetic interference. The result of attitude is affected by many factors, like the low-precision MEMS gyro drift and large body linear acceleration measurements. In this paper, we propose anti-jamming algorithm which is based on four elements of Extended Kalman Filtering (EKF. To reduce carrier linear acceleration and local magnetic field that impact on attitude measurement, the adaptive covariance matrix structure is considered. Moreover, the heading angle correction threshold method is used in magnetic field compensation and interference environment. Based on the experimental results, the effectiveness of the proposed algorithm suppresses the influence of the external magnetic interference on heading angle, as well as improving the accuracy of system attitude measurement.
Mao, Luhong; Li, Cheng; Li, Honglei; Chen, Xiongbin; Mao, Xurui; Chen, Hongda
In the paper, a mixed-interval multi-pulse position modulation (MI-MPPM) scheme for visible light communication (VLC) system is theoretical proposed and implemented on field programmable gate array (FPGA). It has better bandwidth efficiency than PPM and MPPM. And it has better anti-jamming than MPPM. A real-time VLC link based on phosphorescent white LED is also built to measure the performance of the proposed MI-MPPM scheme. The data rate of 104 Mbps in our VLC system under the distance of 60 cm could be achieved, and bit error rate is 3 . 81 × 10-5. As far as we know, it is the highest data rate that can be achieved in continuous real-time VLC system with phosphorescent white LED based on PPM and its derivative modulation. The performance of VLC system under different distances, advantages and the possible application scenarios of MI-MPPM are also discussed.
Full Text Available Navigation Signal based on Compound Carrier (NSCC, is proposed as the potential future global navigation satellite system (GNSS signal modulation scheme. NSCC, a kind of multi-carrier (MC signal, is generated by superposition and multi-parameter adjustment of sub-carriers. Therefore, a judious choice of parameter configation is needed. The main objective of this paper is to investigate the performance of the NSCC which is influenced by these parameters and to demonstrate its structure characteristics and superiority, employing a comprehensive evaluation system. The results show that the proposed NSCC signal processes full spectral efficiency and limited out of band (OOB emissions, satisfying the demands of crowed frequency resources. It also presents better performance in terms of spectral separation coefficients (SSCs, tracking accuracy, multipath mitigation capability and anti-jamming reduction compared with the legacy navigation signals. NSCC modulation represents a serious candidate for navigation satellite augmentation systems, especially for signals applied in challenging environments.
Fan, Jinxiang; Huang, Jianxiong
In recent years, precision guided weapons play more and more important role in modern war. The development and applications of infrared imaging guidance technology have been paid more and more attention. And with the increasing of the complexity of mission and environment, precision guided weapons make stricter demand for infrared imaging seeker. The demands for infrared imaging seeker include: high detection sensitivity, large dynamic range, having better target recognition capability, having better anti-jamming capability and better environment adaptability. To meet the strict demand of weapon system, several important issues should be considered in high-performance infrared imaging seeker design. The mission, targets, environment of infrared imaging guided missile must be regarded. The tradeoff among performance goal, design parameters, infrared technology constraints and missile constraints should be considered. The optimized application of IRFPA and ATR in complicated environment should be concerned. In this paper, some design considerations for high-performance infrared imaging seeker were discussed.
Aziz, Farhan M.
Commercial LTE networks are being studied for mission-critical applications, such as public safety and smart grid communications. In this paper, LTE networks are shown vulnerable to Denial-of-Service (DOS) and loss of service attacks from smart jammers, who may employ simple narrowband jamming techniques to attack without any need to hack the network or its users. We modeled the utilities of jamming and anti-jamming actions played by the jammer and the network under the framework of single-shot and repeated Bayesian games. In a single-shot game formulation the only Nash Equilibria (NE) are pure strategy equilibria at which network utility is severely compromised. We propose a repeated-game learning and strategy algorithm for the network that outperforms single-shot games by a significant margin. Furthermore, all of our proposed actions and algorithms can be implemented with current technology.
Full Text Available In this paper, a pressure distribution sensing system based on wavelet analysis and resistance tomography is proposed to overcome the shortcomings of a traditional electrode type pressure distribution sensor, which needs to be arranged with many electrodes and has a high production cost. The system uses ADS1256, a constant current source module, a serial communication module, a Raspberry host, a touch screen, and other components. The wavelet transform is used to preprocess the collected signal to improve the anti-jamming performance of the system. The method of resistance tomography is used to realize the real-time imaging of pressure distribution. Finally, the reliability of the system is verified using conductive silica gel as a sensitive material. The experimental results show that wavelet analysis preprocessing can significantly improve the quality of pressure distribution imaging.
Dai Hangyang; Deng Sheng; Cui Can
According to the requirements of the integrated and miniaturization boron concentration measurement system, the data acquisition system based on SOPC (System on a programmable chip) achieves the acquisition of the pulse signals and temperature signals, and can decrease the transmitting interference and improve the accuracy of boron concentration measurement. According to the principle of boron concentration measurement, this paper firstly introduces the structure of the data acquisition system, and then carries on the detailed research on temperature acquisition module, pulse acquisition module, digital potentiometer, self-test control module, on-sit display module and telecommunication module. So the multifunctional data acquisition system is integrated into a more complete and flexible SOPC. At last, the testing results verify the reliability, accuracy and anti-jamming capability of boron concentration measurement system based on SOPC. (authors)
Liu, Xianxuan; Yuan, Xueguang; Zhang, Yangan
Optical fiber sensing has many advantages, such as volume small, light quality, low loss, strong in anti-jamming. Since the invention of the optical fiber sensing technology in 1977, optical fiber sensing technology has been applied in the military, national defense, aerospace, industrial, medical and other fields in recent years, and made a great contribution to parameter measurement in the environment under the limited condition .With the rapid development of computer, network system, the intelligent optical fiber sensing technology, the sensor technology, the combination of computer and communication technology , the detection, diagnosis and analysis can be automatically and efficiently completed. In this work, we proposed a noninvasive blood pressure detection and analysis scheme which uses optical fiber sensor. Optical fiber sensing system mainly includes the light source, optical fiber, optical detector, optical modulator, the signal processing module and so on. wavelength optical signals were led into the optical fiber sensor and the signals reflected by the human body surface were detected. By comparing actual testing data with the data got by traditional way to measure the blood pressure we can establish models for predicting the blood pressure and achieve noninvasive blood pressure measurement by using spectrum analysis technology. Blood pressure measurement method based on optical fiber sensing system is faster and more convenient than traditional way, and it can get accurate analysis results in a shorter period of time than before, so it can efficiently reduce the time cost and manpower cost.
Sun Xueliang; Wu Taosheng; Chen Kezhi; Zheng Wenyao; Hao Huaide
The introduction of the safety renovation project of the control and protection system of the swimming-pool research reactor (SPR) is presented. An advanced control and protection system for 49-2 (SPR) has been designed, manufactured, installed and tested. In the design of the new system, the modern measuring and control techniques are employed and the national standards and nuclear safety codes are strictly followed. Protection variables and equipment are modified; Sensitivity increased about 1-2 orders of magnitude; at shutdown condition, 5 independent monitors indicate reactor power at the same time; It has good stability and anti-jamming ability. New type of auto-power adjusting system is of good quality; and the Minimum reactor power for patting into auto-mode is modified to be 10 W level instead of previous kw level. Thus the operation safety is ensured and sensitivity increased; added UPS as backup power supply ensures safe shutdown and the indication of the reactor power at reactor shutdown. This project is the first attempt of the renovation of the control and protection systems of the research reactors in China. The success of the two years safe operation of the new system would be of value for the reconstruction of other research reactors and for the design of the new Research Reactors
Liu Wufeng; Qiao Weimin; Yuan Youjin; Mao Ruishi; Zhao Tiecheng
For heavy-ion radiotherapy, HIRFL-CSR (Heavy Ion Research Facility in Lanzhou-Cooler Storage Ring) needs a long term uniform ion beam extraction from HIRFL-CSR main ring to high energy beam transport line to meet the requirement of heavy-ion radiotherapy's ion beam. Slow extraction control system uses the synchronous signal of HIRFL-CSR control system's timing system to realize process control. When the synchronous event data of HIRFL-CSR control system's timing system trigger controlling and changing data (frequency value, tune value, voltage value), the waveform generator will generate waveform by frequency value, tune value and voltage value, and will amplify the generated waveform by power amplifier to electrostatic deflector to achieve RF-KO slow extraction. The synchronous event receiver of slow extraction system is designed by using FPGA and optical fiber interface to keep high transmission speed and anti-jamming. HIRFL-CSR's running for heavy-ion radiotherapy and ten thousand seconds long period slow extraction experiments show that slow extraction control system is workable and can meet the requirement of heavy-ion radiotherapy's ion beam. (authors)
Qiu, Robert; Guo, Nan; Li, Husheng; Wu, Zhiqiang; Chakravarthy, Vasu; Song, Yu; Hu, Zhen; Zhang, Peng; Chen, Zhe
Dynamic spectrum access is a must-have ingredient for future sensors that are ideally cognitive. The goal of this paper is a tutorial treatment of wideband cognitive radio and radar—a convergence of (1) algorithms survey, (2) hardware platforms survey, (3) challenges for multi-function (radar/communications) multi-GHz front end, (4) compressed sensing for multi-GHz waveforms—revolutionary A/D, (5) machine learning for cognitive radio/radar, (6) quickest detection, and (7) overlay/underlay cognitive radio waveforms. One focus of this paper is to address the multi-GHz front end, which is the challenge for the next-generation cognitive sensors. The unifying theme of this paper is to spell out the convergence for cognitive radio, radar, and anti-jamming. Moore’s law drives the system functions into digital parts. From a system viewpoint, this paper gives the first comprehensive treatment for the functions and the challenges of this multi-function (wideband) system. This paper brings together the inter-disciplinary knowledge. PMID:22454598
Knowles, Gareth J.; Bird, Ross W.; Barrett, Ron
UAV's, UCAV's, miniaturized munitions and smart bombs have a variety of objectives clamoring for easement of weight/volume restrictions. These include anti-jam, explosive, servo control, electronics packaging, GPS and other required functions. The possibility of freeing up valuable real estate in the missile itself is most attractive for such applications. QorTek has developed the first self-contained high authority control surface to replace externally activated steering fins or canards. These flight actuation systems require only external control signal and power. Moreover, the technology easily scales to micro munitions. Because of their unique composite structure, these powerful solid-state devices offer exceptional performance in a durable package suitable for miniature munitions. The purpose of this paper is to discuss new breakthroughs in piezo-actuated technology that minimize vol./weight enabling a self-contained flight control actuation system that eliminates the need for servo controls. The presentation will focus on the new design that enables integration into high angular displacement actuation into a graphite epoxy fabricated RALA flight control actuator that can handle the aerodynamic loading conditions.
Xu, S C; Li, J Q; Zhang, R
Soil is a kind of discrete, multiphase compound that is composed of soil particles, liquid and air. When soil is disturbed by bulldozing plate, the mechanical behavior of the soil will become very complex. Based on the law of action and reaction, the dynamic mechanical behavior of disturbed soil was indirectly analyzed by measuring and studying the forces on the bulldozing plate by soil currently, so a stress-strain virtual measuring system for bulldozing plate, which was designed by the graphical programming language DASYLab, was used to measure the horizontal force Fz acting on the bulldozing plate. In addition, during the course of design, the experimental complexities and the interferential factors influencing on signal logging were analyzed when bulldozing plate worked, so the anti-jamming methods of hardware and software technology were adopted correlatively. In the end, the horizontal force Fz was analyzed with Error Theory, the result shown that the quantificational analysis of Fz were identical to the qualitative results of soil well, and the error of the whole test system is under 5 percent, so the tress-strain virtual measuring system was stable and credible
Full Text Available Technique of FM jamming time domain cancellation suppression based on noise floor estimation with dynamic threshold is researched, by using the colored noise NLR filter estimation algorithm instead of the narrowband filtering algorithm, the problem that the target echo signal is lost in the process of jamming amplitude estimation is solved. Through the phase analysis of the jamming signal, the problem of jamming signal amplitude estimation in the background of echo signal is transformed into the problem of useful signals spectral estimation in colored noise background. Combined with the characteristics of the low frequency components of the useful signal, the traditional NLR filtering algorithm is improved by adding the dynamic threshold, so as to achieve the purpose of colored noise’s non-invasive estimation, and then to obtain more accurate jamming signal amplitude estimation. The simulation results show that compared with the traditional jamming cancellation algorithm, this algorithm can improve the SJR of the echo signal better and the anti - jamming ability is stronger.
Arcangeli, Marie-Laure; Bardin, Florence; Frontera, Vincent; Bidaut, Ghislain; Obrados, Elodie; Adams, Ralf H; Chabannon, Christian; Aurrand-Lions, Michel
The junctional adhesion molecules Jam-b and Jam-c interact together at interendothelial junctions and have been involved in the regulation of immune response, inflammation, and leukocyte migration. More recently, Jam-c has been found to be expressed by hematopoietic stem and progenitor cells (HSPC) in mouse. Conversely, we have reported that Jam-b is present on bone marrow stromal cells and that Jam-b-deficient mice have defects in the regulation of hematopoietic stem cell pool. In this study, we have addressed whether interaction between Jam-b and Jam-c participates to HSPC mobilization or hematopoietic reconstitution after irradiation. We show that a blocking monoclonal antibody directed against Jam-c inhibits hematopoietic reconstitution, progenitor homing to the bone marrow, and induces HSPC mobilization in a Jam-b dependent manner. In the latter setting, antibody treatment over a period of 3 days does not alter hematopoietic differentiation nor induce leukocytosis. Results are translated to human hematopoietic system in which a functional adhesive interaction between JAM-B and JAM-C is found between human HSPC and mesenchymal stem cells. Such an interaction does not occur between HSPC and human endothelial cells or osteoblasts. It is further shown that anti-JAM-C blocking antibody interferes with CD34(+) hematopoietic progenitor homing in mouse bone marrow suggesting that monoclonal antibodies inhibiting JAM-B/JAM-C interaction may represent valuable therapeutic tools to improve stem cell mobilization protocols. © AlphaMed Press.
Zhang, Hua; Zeng, Luan
Binocular stereoscopic vision can be used for space-based space targets near observation. In order to solve the problem that the traditional binocular vision system cannot work normally after interference, an online calibration method of binocular stereo measuring camera with self-reference is proposed. The method uses an auxiliary optical imaging device to insert the image of the standard reference object into the edge of the main optical path and image with the target on the same focal plane, which is equivalent to a standard reference in the binocular imaging optical system; When the position of the system and the imaging device parameters are disturbed, the image of the standard reference will change accordingly in the imaging plane, and the position of the standard reference object does not change. The camera's external parameters can be re-calibrated by the visual relationship of the standard reference object. The experimental results show that the maximum mean square error of the same object can be reduced from the original 72.88mm to 1.65mm when the right camera is deflected by 0.4 degrees and the left camera is high and low with 0.2° rotation. This method can realize the online calibration of binocular stereoscopic vision measurement system, which can effectively improve the anti - jamming ability of the system.
Zhang, Hai-bo; Cao, Li-hua; Geng, Ai-hui; Li, Yan; Guo, Ru-hai; Wang, Ting-feng
Laser pulse code is an anti-jamming measures used in semi-active laser guided weapons. On account of the laser-guided signals adopting pulse coding mode and the weak signal processing, it need complex calculations in the frequency measurement process according to the laser pulse code signal time correlation to meet the request in optoelectronic countermeasures in semi-active laser guided weapons. To ensure accurately completing frequency measurement in a short time, it needed to carry out self-related process with the pulse arrival time series composed of pulse arrival time, calculate the signal repetition period, and then identify the letter type to achieve signal decoding from determining the time value, number and rank number in a signal cycle by Using CPLD and DSP for signal processing chip, designing a laser-guided signal frequency measurement in the pulse frequency measurement device, improving the signal processing capability through the appropriate software algorithms. In this article, we introduced the principle of frequency measurement of the device, described the hardware components of the device, the system works and software, analyzed the impact of some system factors on the accuracy of the measurement. The experimental results indicated that this system improve the accuracy of the measurement under the premise of volume, real-time, anti-interference, low power of the laser pulse frequency measuring device. The practicality of the design, reliability has been demonstrated from the experimental point of view.
Li, Baosheng; Yue, Xiang; Wang, Yicheng; Liu, Shanlin
The rotation center of the optical tomography is not strict in the actual device, resulting in the deviation of the rotation center, so that the final projection image reconstruction effect is not ideal. The method proposed in this paper introduces the sampling and fitting circle method on the basis of the original projection sinusoidal center calibration method, makes a preliminary calibration of the rotation center and makes it more accurate with the gradient operator after the center of the projection sinusoid is positioned. A further central calibration of the object imaging in the optical path transmission is made at the center of the detector target surface according to the gradient. Experiments show that the center position of this method is more accurate than the original sinusoidal calibration and has a reliable basis. Using the gradient operator to judge the effective image clarity, the final reconstructed image also has high resolution and anti-jamming. The feature recognition rate of the image has greatly improved. The experimental results have made a great contribution to obtaining clear and effective information.
Yan, Xu; Guo, Lixin; Cheng, Mingjian; Li, Jiangting; Huang, Qingqing; Sun, Ridong
The probability densities of orbital angular momentum (OAM) modes of the autofocusing Airy beam (AAB) carrying power-exponent-phase vortex (PEPV) after passing through the weak anisotropic non-Kolmogorov turbulent atmosphere are theoretically formulated. It is found that the AAB carrying PEPV is the result of the weighted superposition of multiple OAM modes at differing positions within the beam cross-section, and the mutual crosstalk among different OAM modes will compensate the distortion of each OAM mode and be helpful for boosting the anti-jamming performance of the communication link. Based on numerical calculations, the role of the wavelength, waist width, topological charge and power order of PEPV in the probability density distribution variations of OAM modes of the AAB carrying PEPV is explored. Analysis shows that a relatively small beam waist and longer wavelength are good for separating the detection regions between signal OAM mode and crosstalk OAM modes. The probability density distribution of the signal OAM mode does not change obviously with the topological charge variation; but it will be greatly enhanced with the increase of power order. Furthermore, it is found that the detection region center position of crosstalk OAM mode is an emergent property resulting from power order and topological charge. Therefore, the power order can be introduced as an extra steering parameter to modulate the probability density distributions of OAM modes. These results provide guidelines for the design of an optimal detector, which has potential application in optical vortex communication systems.
Zhang, Zexiang; Hu, Shengbin
The four - rotor unmanned aerial vehicle (UAV) is the object of study, in this paper. In order to solve the problem of poor robustness and low control precision of the four-rotor unmanned aerial vehicle (UAV) control system, and realized the stability control problem of the four-rotor UAV attitude. First, the dynamic model of the four-rotor unmanned aerial vehicle is established. And on this basis, a fuzzy controller is designed, and used to control the channel. Then, the simulation platform is built by Matlab / Simulink simulation software, and the performance of the designed fuzzy controller is analyzed comprehensively. It is also determined whether the algorithm can control the attitude of the four rotor unmanned aerial vehicle. The simulation results fully verify the accuracy of the model, and proved fuzzy controller has better dynamic performance and robustness under appropriate parameters so that UAVs can fly stable. The algorithm can improve the anti-jamming performance and control accuracy of the system, it has a certain significance for the actual four-rotor aircraft attitude control.
Ma, Jichi; Li, Yan; Yin, Chunyong
Nanometer measurement has become more and more important in the development of metrology, material science, microelectronics and biology. Heterodyne Fabry-Perot interferometer can be used in the nonlinear error calibration with an accuracy of nanometer and sub-nanometer order. We can get very high resolution by using heterodyne Fabry-Perot interferometer frequency locking technique in theory. However, the measure uncertainty and the stability of results are worse than the expectation's. In this paper, in order to solve the problems of air refrective index change and temperature excursion, we designed the vacuum system that adjusts the interference light path and built it based on NIM's heterodyne Fabry-Perot interferometer. The key in our design is to reduce the thermic balance time and to ensure reliable hermetization of movable components. The influnce of the change of air refractive index to the measured precision was studied, and the approximate formula of vacuum degree that the system requires was concluded. It has been proved in the experiment that the system works steadily. The system's ability of anti-jamming has been improved, and the demand of the measure surroundings has been lowered. Comparing with capacitance displacement measurement instrument, we conclude that the nonlinear degree of this system in the range of 0.35um, which is longer than half of the wavelength of the laser, is better than 3.9nm.
Niu, Zengyuan; Luo, Xin; Ye, Xiwen; Xiu, Xiaoli; Zhang, Li; Wang, Xin; Chen, Jing
A rapid screening method based on high performance liquid chromatography-linear ion trap/orbitrap high-resolution mass spectrometry (HPLC-LTQ/Orbitrap MS) for 22 disperse dyes in ecological textiles has been established. The target compounds were extracted by pyridine/water (1:1, v/v) by shaking extraction in 90 degrees C water bath. The extracts were then separated by a CAPCELL PAK C18 column (100 mm x 2.0 mm, 5 μm) using gradient elution with acetonitrile-5 mmol/L ammonium acetate containing 0.01% (v/v) formic acid as mobile phases, and finally analyzed by HPLC-LTQ/Orbitrap in positive and negative ESI modes. The retention time and accurate mass of parent ion were used for fast screening of 22 disperse dyes, while the confirmatory analysis was obtained by fragments generated by collision-induced dissociation (CID) MS/MS. Target analysis exhibited high mass accuracy (textiles, and Disperse Orange 37/76 was detected in one of them. With high selectivity and strong anti-jamming ability, this method is simple, rapid, accurate, and it can be used for the inspection of disperse dyes in textiles.
Kong, Zhijie; Li, Ping; Yan, Xiaopeng; Hao, Xinhong
Currently, frequency-modulated continuous-wave (FMCW) proximity sensors are widely used. However, they suffer from a serious sweep jamming problem, which significantly reduces the ranging performance. To improve its anti-jamming capability, this paper analyzed the response mechanism of a proximity sensor with the existence of real target echo signals and sweep jamming, respectively. Then, a multi-channel harmonic timing sequence detection method, using the spectrum components' distribution difference between the real echo signals and sweep jamming, is proposed. Moreover, a novel fast Fourier transform (FFT)-based implementation was employed to extract multi-channel harmonic information. Compared with the traditional band-pass filter (BPF) implementation, this novel realization scheme only computes FFT once, in each transmission cycle, which significantly reduced hardware resource consumption and improved the real-time performance of the proximity sensors. The proposed method was implemented and proved to be feasible through the numerical simulations and prototype experiments. The results showed that the proximity sensor utilizing the proposed method had better anti-sweep jamming capability and ranging performance.
Full Text Available The recruitment of dendritic cells to sites of infections and their migration to lymph nodes is fundamental for antigen processing and presentation to T cells. In the present study, we showed that antibody blockade of junctional adhesion molecule C (JAM-C on endothelial cells removed JAM-C away from junctions and increased vascular permeability after L. major infection. This has multiple consequences on the output of the immune response. In resistant C57BL/6 and susceptible BALB/c mice, we found higher numbers of innate immune cells migrating from blood to the site of infection. The subsequent migration of dendritic cells (DCs from the skin to the draining lymph node was also improved, thereby boosting the induction of the adaptive immune response. In C57BL/6 mice, JAM-C blockade after L. major injection led to an enhanced IFN-γ dominated T helper 1 (Th1 response with reduced skin lesions and parasite burden. Conversely, anti JAM-C treatment increased the IL-4-driven T helper 2 (Th2 response in BALB/c mice with disease exacerbation. Overall, our results show that JAM-C blockade can finely-tune the innate cell migration and accelerate the consequent immune response to L. major without changing the type of the T helper cell response.
Full Text Available Built-in-test (BIT is responsible for equipment fault detection, so the test data correctness directly influences diagnosis results. Equipment suffers all kinds of environment stresses, such as temperature, vibration, and electromagnetic stress. As embedded testing facility, BIT also suffers from these stresses and the interferences/faults are caused, so that the test course is influenced, resulting in incredible results. Therefore it is necessary to monitor test data and judge test failures. Stress monitor and BIT self-diagnosis would redound to BIT reliability, but the existing anti-jamming researches are mainly safeguard design and signal process. This paper focuses on test results monitor and BIT equipment (BITE failure judge, and a series of improved approaches is proposed. Firstly the stress influences on components are illustrated and the effects on the diagnosis results are summarized. Secondly a composite BIT program is proposed with information integration, and a stress monitor program is given. Thirdly, based on the detailed analysis of system faults and forms of BIT results, the test sequence control method is proposed. It assists BITE failure judge and reduces error probability. Finally the validation cases prove that these approaches enhance credibility.
Full Text Available Traditional monopulse angle estimations are mainly based on phase comparison and amplitude comparison methods, which are commonly adopted in narrowband radars. In modern radar systems, wideband radars are becoming more and more important, while the angle estimation for wideband signals is little studied in previous works. As noise in wideband radars has larger bandwidth than narrowband radars, the challenge lies in the accumulation of energy from the high resolution range profile (HRRP of monopulse. In wideband radars, linear frequency modulated (LFM signals are frequently utilized. In this paper, we investigate the monopulse angle estimation problem for wideband LFM signals. To accumulate the energy of the received echo signals from different scatterers of a target, we propose utilizing a cross-correlation operation, which can achieve a good performance in low signal-to-noise ratio (SNR conditions. In the proposed algorithm, the problem of angle estimation is converted to estimating the frequency of the cross-correlation function (CCF. Experimental results demonstrate the similar performance of the proposed algorithm compared with the traditional amplitude comparison method. It means that the proposed method for angle estimation can be adopted. When adopting the proposed method, future radars may only need wideband signals for both tracking and imaging, which can greatly increase the data rate and strengthen the capability of anti-jamming. More importantly, the estimated angle will not become ambiguous under an arbitrary angle, which can significantly extend the estimated angle range in wideband radars.
Ma, Lin; You, Zheng; Liu, Tianyi; Shi, Shuai
Positioning, navigation, and timing (PNT) is a strategic key technology widely used in military and civilian applications. Global navigation satellite systems (GNSS) are the most important PNT techniques. However, the vulnerability of GNSS threatens PNT service quality, and integrations with other information are necessary. A chip scale atomic clock (CSAC) provides high-precision frequency and high-accuracy time information in a short time. A micro inertial measurement unit (MIMU) provides a strap-down inertial navigation system (SINS) with rich navigation information, better real-time feed, anti-jamming, and error accumulation. This study explores the coupled integration of CSAC, MIMU, and GNSS to enhance PNT performance. The architecture of coupled integration is designed and degraded when any subsystem fails. A mathematical model for a precise time aiding navigation filter is derived rigorously. The CSAC aids positioning by weighted linear optimization when the visible satellite number is four or larger. By contrast, CSAC converts the GNSS observations to range measurements by "clock coasting" when the visible satellite number is less than four, thereby constraining the error divergence of micro inertial navigation and improving the availability of GNSS signals and the positioning accuracy of the integration. Field vehicle experiments, both in open-sky area and in a harsh environment, show that the integration can improve the positioning probability and accuracy.
Pawel, Stefaniak; Jacek, Wodecki; Jakubiak, Janusz; Zimroz, Radoslaw
Nowadays, drilling & blasting is crucial technique for deposit excavation using in hard rock mining. Unfortunately, such approach requires qualified staff to perform, and consequently there is a serious risk related to rock mechanics when using explosives. Negative influence of explosives usage on safety issues of underground mine is a main cause of mining demands related to elimination of people from production area. Other aspects worth taking into consideration are drilling precision according to drilling pattern, blasting effectiveness, improvement of drilling tool reliability etc. In the literature different drilling support solutions are well-known in terms of positioning support systems, anti-jamming systems or cavity detection systems. For many years, teleoperation of drilling process is also developed. Unfortunately, available technologies have so far not fully met the industries expectation in hard rock. Mine of the future is expected to incorporate robotic system instead of current approaches. In this paper we present preliminary research related to robotization of drilling process and possibilities of its application in underground mine condition. A test rig has been proposed. To simulate drilling process several key assumptions have been accepted. As a result, algorithms for automation of drilling process have been proposed and tested on the test rig. Experiences gathered so far underline that there is a need for further developing robotic system for drilling process.
Fan, Jinxiang; Wang, Feng
Today's infrared imaging guiding missiles are facing many challenges. With the development of targets' stealth, new-style IR countermeasures and penetrating technologies as well as the complexity of the operational environments, infrared imaging guiding missiles must meet the higher requirements of efficient target detection, capability of anti-interference and anti-jamming and the operational adaptability in complex, dynamic operating environments. Missileborne infrared imaging detecting systems are constrained by practical considerations like cost, size, weight and power (SWaP), and lifecycle requirements. Future-generation infrared imaging guiding missiles need to be resilient to changing operating environments and capable of doing more with fewer resources. Advanced IR imaging detecting and information exploring technologies are the key technologies that affect the future direction of IR imaging guidance missiles. Infrared imaging detecting and information exploring technologies research will support the development of more robust and efficient missile-borne infrared imaging detecting systems. Novelty IR imaging technologies, such as Infrared adaptive spectral imaging, are the key to effectively detect, recognize and track target under the complicated operating and countermeasures environments. Innovative information exploring techniques for the information of target, background and countermeasures provided by the detection system is the base for missile to recognize target and counter interference, jamming and countermeasure. Modular hardware and software development is the enabler for implementing multi-purpose, multi-function solutions. Uncooled IRFPA detectors and High-operating temperature IRFPA detectors as well as commercial-off-the-shelf (COTS) technology will support the implementing of low-cost infrared imaging guiding missiles. In this paper, the current status and features of missile-borne IR imaging detecting technologies are summarized. The key
V. N. Skosyrev
overview in elevation plane ray beam with high directivity and electronic scanning. This method is preferable from the viewpoint of the anti-jamming passive and active interference, as well as reducing electromagnetic visibility.
Ying, Feng; He, Zhang; Xiangjin, Zhang; Kun, Liu
With the monochromatic and the directional capability of the laser, laser detection system is confidential in anti-jamming. Detection accuracy is improved significantly as the result of laser's good orientation ability. Sensitivity is enhanced as laser's high-brightness characteristic. With the development of laser technology and laser devices, laser detections are developed both in civilian and military areas. In the military field, laser detection system has been widely applied in various types of tactical missiles, the technique is more mature. Because photo detectors receive the backscattering echo signal of target in laser detection system, they are required sensitive enough to weak signal. With APD's salient features of high sensitivity, rapid response speed, high response frequency and low noise equivalent power, etc.; PIN is replaced by APD to improve sensitivity of laser detection system in recent years. The signal magnification is inadequate in laser detection system, the detector output is usually amplified by multistage amplifiers. And then the system noise includes detector noise and latter amplifiers noise. With its high internal gain, APD becomes the primary noise source of receiving system. This point can be attested by analyzing the transfer function of laser detection system receiver. To ensure the system detecting ability, APD noise must be mitigated as low as possible. According to a large number of experiments, the power signal-to-noise (SNR) and the best multiplication factor of APD are mostly affected by background radiation and temperature. In order to make APD operate at state of the best multiplication factor, the optimum bias must be selected due to the actual operating circumstance. Therefore, APD realtime compensation must be adopted. The existing APD compensation includes the constant false alarm rate compensation, the noise compensation and the temperature compensation. The features of these compensations are obtained by analyzing