基于脉冲信息的敌我识别信号快速分选识别研究

敌我识别系统在现代战争中占有极为重要的地位。分析了敌我识别系统的分类和工作原理,利用敌我识别信号的先验信息,引入时间序列相似性快速匹配原理,提出了一种基于敌我识别脉冲信息的分选识别方法。仿真结果表明,该算法分选速度快,环境适应能力强,能够较好解决复杂环境下敌我识别信号的快速分选识别问题。     

目标识别

目标识别(target identification)指雷达对搜索空域中已检测到的目标正确地进行识别的方法或处理。合作目标的识别依靠二次大战中开发的敌我识别(IFF)技术，即在我方和友方的每一架飞机上，装有转发机，搜索雷达通过IFF发射机发射信号对目标进行询问，目标上的转发机在规定频率上以编码信号响应，IFF系统接收该响应并用可视符号进行显示。目前世界上大多数空军都采用IFF系统，所有的商用航线均采用其于IFF概念的信标跟踪系统，即所谓的二次雷达(参见二次雷达)。非合作目标识别于雷达和目标之间没有任何通信的情况。在这里，雷达和其操作员通过将可检测目标的参数，例如速度、高度和目标信号特征，诸如幅度、相位、频谱、调制方式等同已知(存库的)目标类型的上述参数进行相关比较来进行识别。非合作目标识别的成功在很大程度上取决于雷达的复杂程度，信号处理系统的先进性和目标有效观测时间的长短。     

综合敌我识别方法研究

针对协作式二次雷达敌我识别只能识别“我方”,不能唯一地确认“敌方”的不足,提出基于协作式敌我识别器和信号情报的综合敌我识别方法,能较好地提供全局性的“敌方”、“我方”和“中立方”信息.介绍了系统组成,描述了系统工作过程,指出了需要进一步研究的技术.     

智能水雷敌我识别及关键参数分析

为了解决传统水雷对敌我双方都构成威胁的问题,在分析敌我识别技术工作原理的基础上,提出了一种智能水雷敌我识别流程和敌我识别装置实现方法,通过理论分析和仿真研究了声传播损失和传播距离、发射信号中心频率之间的关系,分析了影响水雷识别距离的参数,得出了识别距离应不小于1 km的结论,为未来水雷的智能化改造提供了依据.     

雷达询问敌我识别技术

主要从雷达敌我识别综合系统的必要性、实现雷达敌我识别综合系统的可能性、ＲＩＳＳ系统中敌我识别应答机、毫米波敌我识别、非协同目标识别等几方面论述了雷达询问敌我识别技术以及综合化问题。     

北约敌我识别现状与发展趋势

敌我识别是避免战场误伤的重要手段之一。出于多国联合作战中避免战场误伤的考虑,北约各国十分重视敌我识别技术与装备的发展。按照不同的技术体制,介绍了北约MARK XIIA敌我识别系统、战场目标识别系统、多体制单兵敌我识别系统的发展现状,包括系统特点、工作机理和指标对比。结合北约近些年的装备发展,指出北约重视敌我识别体系能力建设,并正在推动敌我识别系统向着高性能、综合化、集成化、小型化、智能化、网络化、无人化发展。最后,讨论了敌我识别后续发展重点及对我军敌我识别领域发展和联合作战运用的借鉴意义。     

敌我识别侦察系统性能需求分析

通过对敌我识别系统工作体制的研究,从侦察系统截获能力上,即空域、频域和能量域.提出敌我识别侦察系统的战术及技术需求,确立了针对敌我识别询问信号的旁瓣侦察方法,并结合敌我识别侦察体制,采用基于功能仿真的方法,给出了侦察系统的灵敏度,最后通过分析敌我识别系统的技术参数,确立了双通道接收机体制,实现了对敌我识别信号的完全接收...     

雷达敌我识别干扰方法研究

雷达敌我识别系统用来识别雷达发现目标的敌我属性,它的基本原理是询问机发射射频脉冲询问信号给应答机,应答机收到后自动发回应答信号完成敌我识别;雷达敌我识别干扰则是利用己方的雷达敌我识别对抗装备对敌方的雷达敌我识别系统实施电子干扰的作战行动。文章通过阐述基本工作原理、分析典型信号特征,介绍了雷达敌我识别系统;针对其存在的弱点,分析了雷达敌我识别干扰的可行性;结合已有研究成果和可行性分析,探讨了压制性干扰、欺骗性干扰和灵巧干扰的方法,对雷达敌我识别对抗技术的深入研究具有一定的意义。     

外军飞机对海目标敌我识别错误机理分析

海战场环境下受复杂识别链路时序关系及海面复杂电磁传播环境影响,飞机时常错误识别海上目标的敌我属性,带来误击事件发生隐患.以北约敌我识别系统Mark XII为研究对象,分析了飞机识别海上目标敌我属性技术机理和信号链路流程,给出了不同链路情况下的敌我识别结果,从系统本身、自然环境、电子对抗等角度对识别错误机理进行了分析.研究结论可为我国空海敌我识别能力的提升提供借鉴,也可为开展国外敌我识别系统电子对抗提供有效支撑.     

射频与激光组合识别方案

分析了MarkXIIA敌我识别系统和激光敌我识别系统的现状,提出了射频与激光组合识别方案。该方案综合利用激光指向性高和Mark XIIA系统识别能力强的优点,通过并行使用射频询问射频应答工作方式和激光询问射频应答工作方式,避免了来自射频询问主波束内的多目标应答问题,在具备多目标处理能力的同时,提高了对密集目标中点目标的敌我属性识别能力。该方案也为单兵提供了可行的敌我识别手段。最后,论述了该方案的实用性,以期为新型敌我识别系统的设计提供参考。     

Dynamic spreading code selection method for PAPR reduction inOFDM-CDMA systems with 4-QAM modulation

We present a new dynamic spreading code selection technique to obtain low peak-to-average-power ratio (PAPR) of an orthogonal frequency-division multiplexing code-division multiple-access (OFDM-CDMA) system with 4-QAM modulation for the down-link in mobile communication. In this method, initially, each user is assigned a low and a high PAPR spreading code, which allows selecting one when the system is operating. The spreading code of each user is dynamically selected so that total PAPR level of the whole user group present in the system is minimized. With the proposed technique, the PAPR level of a system with 10 users and 64 sub-carriers using 64 chip Walsh-Hadamard (WH) codes, can be limited to 15 dB while the worst case theoretical maximum could go up to 28.1 dB. Although 64 chip WH codes are employed to evaluate the performance it can be generalized to all other sets of spreading codes     

对二次雷达敌我识别系统的高重频询问干扰研究

文章介绍了二次雷达IFF系统的工作原理,分析了IFF系统单站、多站工作的目标识别概率。针对IFF系统工作机理中存在的不足,建立了高重频询问干扰模型,从IFF系统的识别概率的角度,论证了高重频询问干扰能提高二次雷达IFF系统的应答占据概率,因而降低IFF系统的识别概率,从而达到干扰IFF系统的目的。     

Source-channel optimized trellis codes for bitonal imagetransmission over AWGN channels

We consider the design of trellis codes for transmission of binary images over additive white Gaussian noise (AWGN) channels. We first model the image as a binary asymmetric Markov source (BAMS) and then design source-channel optimized (SCO) trellis codes for the BAMS and AWGN channel. The SCO codes are shown to be superior to Ungerboeck's codes by approximately 1.1 dB (64-state code, 10^-5 bit error probability), We also show that a simple “mapping conversion” method can be used to improve the performance of Ungerboeck's codes by approximately 0.4 dB (also 64-state code and 10 ^-5 bit error probability). We compare the proposed SCO system with a traditional tandem system consisting of a Huffman code, a convolutional code, an interleaver, and an Ungerboeck trellis code. The SCO system significantly outperforms the tandem system. Finally, using a facsimile image, we compare the image quality of an SCO code, an Ungerboeck code, and the tandem code, The SCO code yields the best reconstructed image quality at 4-5 dB channel SNR     

基于不同信息获取方式的敌我识别系统

本文从宏观的角度出发,通过对目标敌我属性信息特点的分析,提出了多种针对不同敌我识别系统所采用的识别信息获取方式,并分析了不同系统体制的特点,指出了各自存在的问题及局限性,澄清了在敌我识别系统研究领域中的若干模糊概念,最后就不同的作战使用环境,讨论了各种识别系统的适用范围。     

Markov Decision Process Based Multiple Codes Assignment in UMTS WCDMA Mobile Networks

For achieving high transmission rate in mobile multimedia communications, 3G WCDMA systems adopt the Orthogonal Variable Spreading Factor (OVSF) code tree to assign a single channelization code for each accepted connection. Based on the orthogonal characteristic of an OVSF code tree, an allocated code blocks the channelization codes that are on the descendant branches and the ancestral codes of the allocated code. Several researches have been proposed to overcome the code-blocking problem for maximizing system utilization. By using both the code assignment and reassignment mechanisms, the system utilization and code blocking can be improved. Nevertheless, the data rate of traffic classes in such single code assignment system should be powers of two of the basic rate, which is impractical and wastes the system capacity when the required rate is not powers of two of the basic rate. A good solution is to assign multiple codes to a new connection, but causes two drawbacks: high complexity of handling multiple codes and high cost from using more number of rake combiners. Consequently, there is a trade-off between waste rate and complexity of handling multiple codes assignments. In previous researches, high computation complexity of assigning multiple codes for a connection and large number of reassignment codes suppressed the advantage of reducing waste rate. Therefore, we propose an adaptive efficient partition algorithm with the Markov Decision Process (MDP) analysis approach to reduce the large number of reassignment codes while improving waste rate. There are two main motivations in the proposed approach. First, we propose an adaptive efficient partition algorithm to determine multiple codes based on the current state of the OVSF code tree for the new incoming connection. Second, after determining the multiple codes, we adopt the MDP analysis to assign the least-cost code for each determined code. Numerical results demonstrate that the proposed MDP approach yields the least number of reassignments and the least number of codes per connection while reducing waste rate significantly, as compared to other approaches.     

Variable to fixed-length codes for Markov sources

Petry's efficient and optimal variable to fixed-length source code for discrete memoryless sources was described by Schalkwijk. By extending this coding technique we are able to give an algorithm for Markov sources that is easy to implement. We can bound the loss of efficiency as a function of the code complexity and the mismatch between the source and the code. Rates arbitrarily close to the source entropy are shown to be achievable. In this sense the codes introduced are optimal.     

A Bayesian Multiuser Detection Algorithm for MIMO-ODFM Systems Affected by Multipath Fading, Carrier Frequency Offset, and Phase Noise

We derive a novel Bayesian algorithm for multiuser detection in the uplink of a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system employing stacked space-time block codes, such as the stacked Alamouti code with two transmit antennas, and a stacked quasi-orthogonal code with four transmit antennas. The proposed technique accomplishes joint estimation of the carrier frequency offset, phase noise, channel impulse response and data of each active user. Its derivation relies on the specific structure of the transmitted signal and on efficient Markov chain Monte Carlo (MCMC) methods. Simulation results evidence the robustness of the proposed algorithm in both uncoded and coded systems.     

敌我识别系统与一次雷达融合的一种设计方法

介绍了敌我识别（IFF）系统的组成和工作原理,分析了IFF系统和传统一次雷达的区别与联系,并提出了一种融合IFF系统与一次雷达的设计方法。     

Mark XIIA Mode 5系统中的软扩频技术应用

介绍了Walsh码的产生和解码原理,阐述了基于Walsh码软扩频在敌我识别(IFF)Mark XIIA Mode 5系统中的应用,利用Simulink平台建立仿真模型,实验结果表明,软扩频技术的应用有效地提高了系统的抗干扰性能。