一种改进的CPFSK信号频率估计方法

针对突发信号解调中多普勒频偏大的问题,提出了一种改进的连续相位移频键控信号(CPFSK)频率估计方法.首先接收信号平方运算使信号的调制指数加倍,再通过一次离散傅里叶变换(DFT),用搜索信号平方谱谱峰的方法实现突发信号频率估计.仿真实验表明,在低信噪比条件下,该算法的频率估计精度比经典的相位差频率估计算法提高了20%;该算法与广泛用于高动态突发信号的频率插值估计算法相比,同道干扰信道下信干比改善可达4 dB,DFT长度缩短约1/3.     

一种短时突发PSK信号的自适应解调方法

短时突发相移键控（PSK）通信具有隐蔽性好、信道利用率高的特点，得到广泛应用。将已调信号非线性放大、限幅处理，使其幅度稳定在一定范围，基于锁相原理得到与已调信号同步的本地载波，是PSK信号解调相干载波恢复的常用方法。然而接收信号的非线性处理，会使PSK信号信噪比急剧下降，影响载波相位跟踪精度，给帧同步信号生成和码元抽取带来不确定性，导致误码率升高。针对常规方法存在的问题，提出了基于Hilbert变换的短时PSK信号自适应解调算法，通过信号归一化，在不降低解调信号信噪比情况下，确保载波恢复运算不受数据信号幅度的影响，具有恢复速度快、跟踪精度高、帧同步信号解调可靠、码元采样时间准确的特点。     

一个混沌保密通信方案的改进

对文献[1]中的一个方案作了改进。用混沌映射信号作保密通信系统的调制载波,对待加密传输的信息信号进行调制,不需要用其它混沌同步方法,利用模运算在接收端直接完成混沌载波的恢复,从而恢复信息信号;为了更好地隐匿信息信号特征,借鉴混沌掩盖对信息信号幅度进行限制,使密文完全随机化。仿真结果表明:该加密系统加密效果好,且能抵御密码分析。     

Synchronous longitudinal reference signal generation—An experimental study of its use in automatic vehicle control

A method of obtaining a continuous reference signal for use in the synchronous longitudinal control of automated ground transport systems is presented and evaluated in preliminary full-scale tests. The results of the latter, which were obtained using a reference signal in conjunction with an instrumented vehicle at speeds from 0 to 46 ft/s over 1600 ft of roadway, are presented. Successful operation was achieved with both steady-state and time-varying velocity command signals. A significant finding, with respect to implementation of the method, was that the roadway environment introduces signal attenuation (2 dB/100 ft) that must be circumvented before practical long-distance operation can be achieved. However, with system refinement, the technique holds great promise for future implementation.     

长线传输的阻抗匹配设计

通过计算长线传输中的阻抗匹配和设计隔离电路,达到了减少高频信号反射,提升能源效益的目的.根据多种设计原则,提出了一种行之有效的匹配方法.采用该匹配方法可减小雷达信号的传输误差,并为测试系统技术在阻抗匹配研究中的应用,以及分析控制特征阻抗带来一定的参考价值.     

PWM变换器并联运行的小信号分析

对开关电源进行模块化设计和并联运行是提高系统可靠性和扩大供电容量的有效手段。但电源的并联运行需要采用均流措施。均流方法多种多样,其中效果较好的是自主均流法。文中采用小信号分析法对PWM变换器及其并联运行所采用的自主均流法进行了建模和仿真分析,结果验证了自主均流法的三环控制的合理性。     

A method for spark rejection in ultraviolet flame detectors

A novel method is presented to render ultraviolet (UV) flame detectors insensitive to ignition spark radiation. The method involves isolating the signal due to the sparks from the UV sensor output and subtracting a DC signal proportional to it from the output of the flame detector sensor system. A practical demonstration of the method is given using a commercially available UV flame detector with the addition of an analog circuit to perform the necessary signal processing. A selectivity improvement to spark radiation of greater than 130 has been obtained. The method is robust in that it is independent of the distance between the light source and the flame detector and has been designed to work with different spark generators found on the market. The analog circuit is simple, requiring few components, thus ensuring rugged, fail-safe operation and low cost     

新型通用雷达侦察信号处理硬件平台

信号处理机是雷达侦察设备的重要组成部分,提高其工作性能、处理能力、可靠性,应用灵活性、通用性、标准化,以及减小体积、降低功耗都具有极其重要的意义。首先介绍信号处理硬件平台的现状及需求,然后提出了一种基于CPCI标准由TMS320C6455双DSP加FPGA通用信号处理平台的设计方案,并详细讨论了该平台的硬件组成、工作原理、特点以及实现方法。     

Observer using low-frequency injection for sensorless induction motor Control-parameter sensitivity analysis

The zero-frequency vector control of an induction motor without a speed sensor has proven to be a very difficult task. Uncertainty and variation in the electrical parameters of the motor deteriorate the performance of fundamental-wave flux observers as the frequency approaches zero, and observers based on high-frequency signal injection rely on motor-specific phenomena. A new method has recently been proposed, where a low-frequency current signal is injected in the estimated rotor flux direction. If there is an error in the orientation, the signal gives rise to a torque oscillation and affects the back electromotive force (EMF) through the mechanical system. The phenomenon makes it possible to reach sensorless zero-frequency operation. This paper shows that the method is insensitive to the variation of the motor parameters. Experiments confirm the result.     

基于形态滤波的心电信号基线矫正算法

基线矫正是心电(ECG)信号预处理中的一个重要步骤.本文提出了一个基于形态滤波的ECG信号基线矫正算法.首先,对原始输入ECG信号进行基于相同结构元素的形态开闭-闭开滤波,抑制其中的QRS波群;然后,采用两个不同宽度的结构元素,对去除QRS波群后的ECG信号进行广义形态开-闭滤波,分离出基线漂移信号;最后,用原始ECG信号减去估计出的基漂信号,得到经过基线矫正的ECG信号.仿真实验与实际应用结果表明,本文方法不仅可以有效去除ECG信号中的基漂干扰,而且较好地保持了ECG信号的原有特征形态,处理效果明显优于以往算法.     

电子战系统作战效能灰色层次评估

电子战系统作战效能评估是电子战领域的一个重要课题。由于电子战系统在信息化战场上处于错综复杂的信号环境中,影响其作战效能的因素很多,针对电子战系统信息少和不确定性的特点,提出运用灰色层次评估法对电子战系统作战效能进行评估。构建了电子战系统作战效能指标体系框架,建立了灰色层次数学模型。以某型通信对抗系统为例,进行了评估仿真,结果证明该灰色层次评估方法科学有效。     

生物基因技术在多功能雷达信号解析中的应用

多功能雷达作为一个大规模动态系统,具有复杂的信号形式.对其信号进行解析,揭示系统内部的运行规律,是当今电子侦察领域面临的严重挑战.本文借鉴生物基因工程的思想,提出了多功能雷达信号解析的研究框架和研究手段.详细分析了多功能雷达的工作机制,从系统的角度,将其与生物体的细胞做类比,指出两者在系统结构和运行机制上的高度相似性.对生物基因工程中的逆向工程等关键技术进行了总结,在此基础上,讨论了其在多功能雷达信号解析领域的应用前景.前期的研究成果表明了本文方法的合理性.     

一种新的混沌同步及保密通信方式

本文提出一种新的混沌同步及保密通信方式。在发送端，将信息信号与混沌载波的和经取模运算后再嵌入混沌动力系统的迭代之中以实现调制；在接收端，用一个相应的非动力学系统从接收信号中提取混沌载波并进而恢复信息信号。研究表明，该混沌同步方式具有较强的抗干扰能力并且实现容易；该保密通信系统保密性能良好。     

地面运动目标振动信号的特性分析与目标识别

地面目标振动信号的特征提取是进行目标识别技术的关键,针对人员行走、车辆行驶等地面目标运动时产生的振动信号,首先进行实验测试建立包含反映目标属性特征信息的信号样本数据库,然后通过过零数分析方法得到信号的时域特征,实现了单人与车辆的目标识别,最后采用Welch谱分析法对信号进行了频域分析并实现了单人与多人的目标识别。实验表明这两种方法简便、易实现,有较好的识别效果。     

Timing Jitter Reduction by All-Optical Signal Regeneration Using a Polarization Bistable VCSEL

All-optical signal regeneration is experimentally demonstrated using a polarization bistable vertical-cavity surface-emitting laser. The retiming operation of signal regeneration is performed by using an AND gate operation and a reset operation. An optical clock pulse and input data signal are used for the AND gate operation. The timing jitter of the regenerated signal is reduced by optimizing the injection power ratio of the clock pulse and the data signal. The retiming operation is analyzed using a simple model that includes random fluctuation of the polarization switching threshold and bandwidth limitation of the response to the injection light.      

简易函数信号发生器与计数器设计

介绍了简易函数信号发生器与计数器设计的基本方法和应用;并详细叙述了单元电路结构、信号走线、信号控制方法、整机基本工作原理以及在实际应用中的调试方法及注意事项.     

Adjoint sensitivity models and signal-flowgraph reversal

The method of Seviora and Sablatash for obtaining adjoint digital filters is interpreted for general signal-flowgraph application. It is shown that the procedure reduces to the reversal operation for signal flowgraphs. Motivated by this result, a simple alternative derivation of the adjoint signal flowgraph is presented which is based on direct sensitivity models and Mason's topological formula. Tellegen's theorem or the calculus of variations are not required. The derivation is an extension to interreciprocal linear systems of an argument used by Leeds and Ugron for reciprocal networks.     

基于SMI－CMA联合自适应算法的性能分析

恒模算法(CMA)被广泛地应用到盲自适应波束形成中，除了传输信号波形具有恒定的包络外．CMA不需要先验知识。基于SMI—CMA算法的恒模(CM)阵列级联的结构，由SMI算法决定CMA的初始权向量．系统可以分离多个同信道信源，在干扰信号较强时，仍有稳定的SINR输出，具有较好的收敛速度。仿真结果也证明了SMI—CMA算法具有较强的稳健型和较快的收敛速度。     

一种新型复杂电磁环境模拟器的设计与实现

介绍了目前国内复杂电磁环境模拟器的发展现状，提出了一种新的复杂电磁环境模拟器的实现方法。该方法提高了信号密度，丰富了信号的样式，基于宽带相控阵天线的设计可同时照射多个目标，模拟TWS（边扫描边跟踪）或TAS（边跟踪边搜索）扫描。文中同时介绍了诱饵源配合模拟器在试验和实战中的布阵设计思想和应用方案。以上设计方法已经在实际项目中采用，并正常运行，实践证明了该思路的可行性和有效性。     

An iterative algorithm for signal reconstruction from bispectrum

The author presents a procedure to reconstruct a (minimum or nonminimum phase) discrete-time signal from its bispectrum. The algorithm is iterative and based on using the method of projections onto convex sets (POCS) in an inner product space in which the vector space consists of real sequences, and vector addition, is defined in terms of the convolution operation. Prior information, such as an energy bound on the signal, can be incorporated into this algorithm. An algorithm that employs energy information was found to produce better results in simulation than one that ignores energy constraints