高重频激光对激光制导武器的干扰及抗干扰措施研究

简要介绍了激光制导原理,通过对高重频激光对激光半主动制导武器的干扰机理和激光导引头抗干扰措施的分析,提出了采用这种干扰方法应注意的一些实际问题。     

高重频激光对激光制导武器的干扰机理分析

为了研究高重频激光对激光制导武器的干扰机理,根据高重频激光干扰原理,建立了半主动激光制导导引头编码识别模型、时间波门模型、多信号处理模型和干扰信号调制处理模型等相关理论模型,提出了导引头干扰有效的3σ判定准则。在此基础上重点研究了多源干扰和信号调制特性对高重频激光干扰效果的影响,并进行了仿真系统测试。结果表明,多源干扰和干扰信号频率调制能够有效增强干扰效果,干扰信号幅值调制对干扰效果改善作用并不明显。该研究结果将为高重频激光干扰效果评估和高重频激光干扰系统应用提供理论参考。     

高重频激光对激光制导武器的干扰机理分析

为了研究高重频激光对激光制导武器的干扰机理,根据高重频激光干扰原理,建立了半主动激光制导导引头编码识别模型、时间波门模型、多信号处理模型和干扰信号调制处理模型等相关理论模型,提出了导引头干扰有效的3σ判定准则。在此基础上重点研究了多源干扰和信号调制特性对高重频激光干扰效果的影响,并进行了仿真系统测试。结果表明,多源干扰和干扰信号频率调制能够有效增强干扰效果,干扰信号幅值调制对干扰效果改善作用并不明显。该研究结果将为高重频激光干扰效果评估和高重频激光干扰系统应用提供理论参考。     

被动单脉冲导引头对噪声调频干扰的角跟踪

研究了被动振幅和差单脉冲导引头对宽带噪声调频干扰源的响应和跟踪特性，并重点研究了主波束内存在两个非相干干扰源的情况下导引头的角跟踪规律，最后提出了在存在两个噪声调频干扰时导引头提取角信号的一种方法，计算机仿真验证了该方法的正确性和有效性。     

基于STUKF的激光平台导引头干扰力矩在线补偿方法研究

隔离度会降低导引头输出信息的精度,增加导弹的脱靶量。针对激光平台导引头的隔离度问题,首先建立了考虑隔离度寄生回路的制导系统模型,经分析确定干扰力矩为引发隔离度的主要原因,并提出采用滤波算法对其进行估计补偿的方案。之后依据平台导引头的基本结构与干扰力矩的产生机理建立了用于在线辨识隔离度的非线性滤波模型,采用强跟踪无迹卡尔曼滤波算法（STUKF）补偿建模误差,解决了干扰力矩难以精确建模的问题,以对其进行在线辨识与前馈补偿。最后对所提方法进行了数学仿真与半实物仿真实验论证,实验结果表明:所提方法可增强导引头光轴对弹目视线角速度的跟踪能力,改善导引头输出制导信息的品质,并有效地抑制隔离度,达到提升系统制导精度的目的。     

高重频激光对激光半主动制导武器干扰技术研究

通过对激光半主动制导武器制导机理和抗干扰技术的分析,阐述了高重频激光对激光半主动制导武器的干扰机理和应用特点,为进一步的理论研究和工程实践提供帮助。     

激光导引头四象限探测器测角精度的建模研究

四象限探测器对目标的测角精度直接影响激光制导武器的制导精度,因此研究四象限探测器测角精度十分重要。采用计算和仿真分析的方法,基于导引头入瞳处脉冲峰值功率密度服从均匀分布,噪声干扰电流服从高斯分布,建立了激光导引头光束偏转角误差模型;但由于噪声干扰使光束偏转角误差具有随机概率性,所以将光束偏转角误差的均值和标准差作为四象限探测器测角精度的衡量标准,分别建立了光束偏转角误差的均值和标准差与导引头光学系统参数、光斑半径、漫反射激光入射角、噪声干扰电流以及导引头入瞳处脉冲峰值功率密度之间的关系,并以导引头光束偏转角误差标准差为例,结合应用背景进行了仿真分析。     

汇聚噪声干扰对HFC上行信道传输性能的影响

HFC网络上行信道所面临的至关重要的问题就是噪声抑制问题。一般来说，影响数据传输的主要是上行信道的汇聚噪声干扰。章分析、仿真了汇聚噪声干扰对HFC上行信道的影响。仿真使用ImportanceSampling（IS，重点抽样）方法，较常用的Monte-Carlo方法，它能显地减少运算时间。     

空空导弹导引头位标器质量不平衡对制导精度的影响

空空导弹导引头位标器质心与回转中心的重合度要求极为严格。本文主要分析格斗导弹导引头位标器质心偏差对制导精度的影响；以及导弹动特性不同时，位标器质心偏差对制导精度的影响，要得到满意的制导精度，位标器质心偏差要求不超过０．７×１０＾－５ｍ。     

大气湍流对激光半主动制导精度的影响

根据强度起伏导致的对数振幅方差和相位起伏导致的到达角方差,计算出由大气湍流引起的激光半主动制导跟踪系统的角误差,并通过专用软件仿真了大气湍流引起的角误差对激光半主动制导瞄准精度的影响。计算和仿真结果表明:大气湍流引起的跟踪误差可达几十微弧度,导致制导系统的瞄准精度下降10%左右。     

光源噪声对光纤光栅解调精度的影响

采用耦合模型理论对光纤光栅的传输特性进行了分析,运用矩阵法对均匀光纤光栅反射谱进行了数值模拟。分析了光学检测中的噪声来源,并对实验室条件下使用激光器时噪声的大小进行了估算和验证。通过对光源施加不同功率大小的噪声,并根据光纤光栅的反射谱来研究光源噪声对峰值检测的影响。实验表明,激光器的功率噪声对光纤光栅解调精度有很大影响,波长检测精度越高,噪声影响越大,在解调精度达到皮米级时,激光器的噪声应接近量子噪声的极限水平。为光纤光栅技术在高精度装备检测中的应用和研究提供理论基础。     

导引头隔离度对最优落角制导律制导性能影响研究

针对工程应用中最优落角制导律性能受导引头隔离度影响的问题,基于最优落角制导律（GLTIA）和拓展最优落角制导律（EGLIA）,建立了包含捷联导引头隔离度寄生回路的最优落角制导律系统,研究了捷联导引头隔离度对制导系统稳定性的影响,利用伴随函数法,通过仿真对比分析了捷联导引头隔离度对GLTIA和EGLIA制导精度的影响。仿真结果表明:相比正反馈情况,当捷联导引头隔离度寄生回路为负反馈时,最优落角制导律具有较高的稳定域,系统稳定性会随着隔离度幅值的增大而减小。相比于GLTIA,EGLIA的制导性能更优,但导引头隔离度对其制导性能的影响也更为严重,在实际工程应用中,要保证最优落角制导律有较高的制导性能,EGLIA和GLTIA需将导引头隔离度水平分别控制在2.5%和3.5%以下,以降低寄生回路对制导系统稳定性的影响。     

全捷联对地攻击制导武器导引头隔离度对制导系统性能的影响

针对全捷联图像导引头隔离度问题,分别推导了由探测器和角速率陀螺之间的刻度尺系数误差及动力学偏差引起的隔离度传递函数;采用系数冻结法及劳斯判据分析了含有隔离度寄生回路的制导系统稳定区域,给出了不同无量纲末导时间下制导系统稳定时刻度尺误差和动力学偏差的取值范围;利用伴随函数法研究了隔离度对制导精度的影响。以上研究结果可以为全捷联制导武器制导控制系统参数设计提供参考,对于隔离度正反馈的情况应予以更多关注。     

激光成像雷达扫描性能的检测精度

为实现对激光成像雷达扫描系统性能的高精度检测,完成了激光束扫描性能检测设备的研制.对该设备的检测精度进行了分析,着重研究了提高设备检测精度的方法,根据检测设备的检测原理和使用特点,提出了在数据处理环节校正光学系统畸变和利用二次成像法精确测量光学系统焦距的方法,使检测设备对扫描角的检测精度提高一个量级,实验及分析结果表明:采用上述改善精度方法后,该设备对扫描角的检测精度可以达到1.2 mrad.改进的设备可以对扫描成像激光雷达的扫描系统性能作高精度的检测.     

Effect of semiconductor laser phase noise on BER performance in an optical DPSK heterodyne-type experiment

We report the first experimental investigation of the effect of laser-diode phase noise on the error-rate performance in a PSK heterodyne differential detection fibre communication experiment. A newly designed AlGaAs laser emitter with adjustable linewidth is used as both the signal carrier and the local oscillator. Error rate is measured for 25 Mbit/s and 50 Mbit/s signals at an intermediate frequency of 250 MHz, and a BER (bit error rate) of 10?10 has been achieved.     

Assessment of laser noise influence on direct-detection transmission system performance

A new semi-analytical method of estimating the influence of laser noise on directly modulated direct-detection transmission system performance is proposed. Its accuracy is assessed for different propagation situations and receiver noise type dominance using rigorous mixed semi-analytical simulation. Two different relative intensity noise (RIN) powers at receiver input associated with the two laser currents of the binary levels are considered, and not just a single one corresponding to the laser average current as in other published works. It is shown that, to perform rigorous simulation, suitable methods of solving stochastic laser rate equations should be used, and a number of samples high enough in order to stabilize the sensitivity estimator should be considered. It has been found that, for power penalties of about 1 dB, more than 150 samples may be necessary. For a power penalty due to laser noise of about 4.5 dB, discrepancies not exceeding 0.4 dB are observed between the results obtained using the new semi-analytical approach and using the rigorous simulation. It is shown that the new semi-analytical approach gives more precise results than other approach currently used. For a power penalty due to laser noise not exceeding 2 dB, the discrepancies between the two approaches can reach roughly 1 dB. It is shown that these discrepancies can increase with the laser linewidth. Explicit expressions for system power penalty due to the RIN at the fiber output are presented, for both signal-independent and -dependent noise dominance. It is shown that these expressions give good upper bounds of the real power penalties.     

Effect of thermal noise and APD noise on the performance ofOPPM-CDMA receivers

The effect of thermal noise and avalanche-photodiode (APD) noise on the performance of optical overlapping pulse-position modulation/code-division multiple-access (OPPM-CDMA) systems with and without double optical hardlimiters is examined. Comparisons with the corresponding optical on-off keying/CDMA (OOK-CDMA) systems are presented as well. The maximum data rate that can be achieved under laser pulsewidth and bit error rate constraints is determined. It is shown that about 10 dB increase in the average power, with respect to the Poisson shot-noise-limited system, is required to compensate for the performance degradation due to thermal noise and APD noise. Moreover, it is indicated that for a bit error rate not exceeding 10^-9, a laser pulsewidth of 0.03 ns, and an average received optical power of -55 dBm, a data rate of more than 3 Gb/s can be achieved per channel when using OPPM-CDMA systems with double optical hardlimiters     

Amplifier techniques for combining low noise, precision, and high-speed performance

A monolithic operational amplifier is presented which optimizes voltage noise both in the audio frequency band, and in the low frequency instrumentation range. In addition, the design demonstrates that the requirements for low noise do not necessitate compromising the specifications in other respects. Techniques are set forth for combining low noise with high-speed and precision performance for the first time in a monolithic amplifier. Achieved results are: 3 nV//spl radic/Hz white noise, 80 nV/SUB p-p/ noise from 0.1 to 10 Hz, 17 V//spl mu/s slew rate, 63 MHz gain-bandwidth product, 10 /spl mu/V offset voltage, 0.2 /spl mu/V//spl deg/C drift with temperature, 0.2 /spl mu/V/month drift with time, and a voltage gain of two million.     

Effect of laser noise on analogue fibre optic systems

A simple theory taking into account both source noise and receiver noise contribution to the s.n.r. performance of analogue fibre optic systems is derived and experimentally verified. Experiments indicate that high quality a.m.-v.s.b. video transmission (s.n.r. > 60 dB) is not feasible with state-of-the-art gain-guided laser diodes.     

Effects of laser phase noise on the performance of optical coherent receivers

Laser phase noise (LPN) plays an important role in optical coherent systems. Based on the algorithm of Viterbi-Viterbi carrier phase estimation (CPE), the effects of LPN imposed on the coherent receivers are investigated for quadrature phase shift keying (QPSK), 8 phase shift keying (8PSK) and 16-quadrature amplitude modulation (16-QAM) optical coherent systems, respectively. The simulation results show that the optimal block length in the phase estimation algorithm is a tradeoff between LPN and additive white Gaussian noise (AWGN), and depends on the level of modulation formats. The resolution requirements of analog to digital converter (ADC) in the coherent receivers are independent of LPN or the level of modulation formats. For the bit error rate (BER) of 10-3, the required bit number of ADC is 6, and the gain is marginal for the higher resolution.