Trimode ladar/radar transponder systems for tracking long range cooperative targets

Detection and tracking of cooperative airborne targets are very important for military and also for civilian purposes. Previous research has shown that detection and tracking LASER offer high precision but their operation range is limited to less than 40 km even in good visibility propagation conditions. For long operation ranges, high power and bulky RADAR are required which can be significantly reduced by using active transponders on the cooperative target. A trimode LADAR/RADAR/Transponder system is investigated providing optimum performances. A L band Radar with active transponder is operated for all weather long ranges up to Low Earth Orbit satellites. The L mode is switched to a Mm wave mode RADAR for operation distances lower than 350 km and to an accurate LASER mode for the final tracking steps.     

地对空雷达干扰系统跟踪精度技术分析

 阐述了地对空雷达干扰系统中角跟踪统系统组成和工作原理，重点分析了影响跟踪精度的主要原因。分析和提出了提高跟踪精度的方法和措施。     

地对空雷达干扰系统跟踪精度的技术分析

阐述了地对空雷达干扰系统中角跟踪统系统组成和工作原理，重点分析了系统随机误差等影响跟踪精度的六点主要因素，提出了利用计算机控制技术对系统误差进行修正以提高跟踪精度的方法和措施。     

Point-based integration for 3D object reconstruction from Ladar range images

A method of point-based integration from multiple registered laser radar (Ladar) range images for 3D object reconstruction is presented in this literature. Our method operates surface point data directly and provides a direct way for overlapping data removal. The overlapping areas were detected using a single distance threshold. In order to set the distance threshold, a local point density approach is introduced to solve it. Compared with the mesh-based, volumetric and other points-based integration approaches, our method is simple and fast, and need less storage memory. The approach is performed on various objects with different geometric shapes. The experimental results demonstrate the efficiency and feasibility of our method.     

Processing for laser radar range images

Imaging laser radar can give intensity and range images, which provide integrated 3-dimensional (3D)information about objects. However, dropouts and range anomalies exacerbate range images, which makes their background cluttered and target blurred. For background suppression, a new algorithm that combines intensity image and its mean is presented. By using this algorithm to process actual laser radar range images, most background noises are suppressed. According to range anomalies characteristics, multitemplate selection order mean filtering algorithm is presented and used for actual ladar range images where the distance between two targets is 77 m. This algorithm obtains the clear range image in which the interval of two objects is 75 m. The result shows that the processing algorithm is correct and effective.     

光电跟踪系统稳定精度测试方法研究

针对光电跟踪系统稳定精度测试需求,提出一种稳定精度动态测试方法。该方法基于光学自准直原理,采用面阵CCD探测器,结合图像求取质心算法,实现被测系统的动态测试,通过该装置获得了稳定精度测试结果。结果表明:测试50 rad级两轴两框架系统动态稳定精度,通过该测试方法测出其稳定精度最大为48 rad。     

二次偏振调制测距系统中调制频率与测距精度的关系

本文在基于二次偏振调制激光测距系统的基础上, 对调制频率与激光测距系统精度的关系做了深入的理论推导和实验验证. 最终得出结论: 相位法激光测距系统的测量精度会随着调制频率的增大而提高, 且精度的提高程度正比于调制频率的不确定度Δf与测程范围内半波长数N值的比值. 并通过选取合适的调制频率来提高系统的测距精度, 提高后的测距精度可达10^-7.     

舰载光电系统高精度跟踪控制技术

在舰船摇摆条件下提高光电跟踪系统对目标动态跟踪精度，其控制系统设计的关键技术是隔离扰动和减小高速跟踪时的动态滞后误差。对几种陀螺反馈惯性空间稳定技术进行了详细叙述和对比，得到了采用高测量带宽的陀螺反馈回路可以有效提高系统隔离度，并推导出系统隔离度的计算公式。同时，介绍了计算机辅助跟踪技术的原理以及在陀螺反馈惯性稳定技术的基础上结合计算机辅助跟踪的综合控制技术在舰载光电设备上的应用。以数据说明了这种综合控制技术的有效性和实用性。     

Simultaneous dual mode add/drop multiplexers for optical interconnects buses

For the potential realization of optical interconnect scheme based on modal diversity, we propose and analyze efficient mode add drop multiplexers (MADM). Each of the two types of MADM proposed here enables a simultaneous two channels (modes) add/drop to/from a multimode bus. The simultaneous operation is of importance in reducing the device footprint within the expected ultra-dense interconnects schemes. We developed analytical design rules for the adiabatic devices and verified by simulation that an implementation based on Silicon over Insulator waveguides, is exhibiting low loss and low channels crosstalk (below −22 dB).     

System feasibility study of a microwave/millimeter-wave radar for space debris tracking

A 35 GHz millimeter-wave radar system has been studied for space debris tracking. The objective is to track the particles ranging in size from 4 mm to 80 mm up to a range of 25 km. The system requires various state-of-the-art technologies including phased arrays, monopulse tracking, pulse compression, high power transmitters, low noise receivers, and pulse integration signal processing techniques.     

Optimized LADAR/RADAR system for detection and tracking

The LADAR (LAser raDAR) is limited in detection and tracking of cooperative targets to less than 30 km range for ground and low altitude systems as has previously been found. This paper addresses the optimized design of a dual mode LADAR/RADAR system with respect to operation ranges. Computational results for specific RADAR Systems show significant improvements for cooperative target detection and tracking ranges beyond 30 km up to 450 km even under severe atmospheric conditions. The price for range improvement is enhanced complexity of the LADAR system and reduced tracking accuracy in the first steps of the detection process.     

Optimized LADAR/RADAR system for detection and tracking

The LADAR (LAser raDAR) is limited in detection and tracking of cooperative targets to less than 30 km range for ground and low altitude systems as has previously been found. This paper addresses the optimized design of a dual mode LADAR/RADAR system with respect to operation ranges. Computational results for specific RADAR Systems show significant improvements for cooperative target detection and tracking ranges beyond 30 km up to 450 km even under severe atmospheric conditions. The price for range improvement is enhanced complexity of the LADAR system and reduced tracking accuracy in the first steps of the detection process.     

空间激光通信系统动态跟瞄参数测试方法研究

跟瞄精度是空间激光通信系统捕获、跟踪和瞄准(acquisition,tracking and pointing, ATP)分系统的重要指标参数之一,其准确测量是评估空间激光通信系统远距离通信性能的关键。介绍了空间激光通信系统ATP分系统跟瞄精度的测试方法,设计了一种基于平行光管法的空间激光通信系统动态瞄参数测量装置,分析和讨论了影响动态跟瞄精度测量不确定度的因素。试验表明,该测量装置在100 Hz振动频率条件下,ATP分系统稳定精度测量不确定度达到1.9 μrad(k=2),可用于空间激光通信系统ATP分系统跟瞄参数检测以及远距离激光通信性能评估。     

Correlation recognition for range image of laser radar

The target recognition of laser radar becomes hot research in recent years, because laser radar can produce high space resolution and collect rich target information, such as range image, intensity image and Doppler image. In the vertical detection of laser radar, the problem of in-plane target rotation invariance is firstly solved. In the paper, a new support vector machine (SVM) correlation filter is presented, which simultaneously has the attractive attributes of SVM and common correlation filter. Exploiting the idea of margin of separation maximization, the design criterion is produced. The filter is synthetic by the multiple training images which are generated by rotating one image. The real range images of laser radar are used to finish the correlation experiments. The results show that the filter is not sensitive to the noise, the correlation peak is changed slightly for the different testing images, and the precision of location is high.This design way can be used in other recognition fields.     

移动地面站宽温度跟瞄系统信标接收镜头

为了保证移动地面站光电跟瞄系统在野外复杂环境下具有稳定的跟踪精度,针对-20~40℃宽工作温度范围下信标接收镜头成像光斑弥散的问题,进行了光学系统与光机结构的设计,提出了一种以步进电机驱动补偿镜组的温度补偿方案。分析了极限温度条件下光学系统性能的改变以及不同温度补偿方案的效果,针对光电跟瞄系统的指标要求,设计了光机结构并进行了力学、光学性能的分析。分析结果表明,系统一阶模态为370 Hz;补偿镜组向前移动0.695 mm能够补偿-20℃时光学系统成像光斑的弥散,令中心视场光斑尺寸由73μm降为3.2μm,边缘视场光斑尺寸由77μm降为15.7μm;向后移动0.885 6 mm能够补偿40℃时成像光斑的弥散,令中心视场光斑尺寸由94μm降为3.9μm,边缘视场光斑尺寸由96μm降为21.8μm;使用ZYGO干涉仪对光学系统的像质进行检测,波像差RMS值(均方根值)为0.061λ(λ=632.8 nm),PV值(峰谷值)为0.466λ,能够满足跟瞄系统指标要求。     

Reduction of range walk error in direct detection laser radar using a Geiger mode avalanche photodiode

In this paper a new technique to improve the accuracy of direct detection time-of-flight (TOF) laser radar using a Geiger mode avalanche photodiode (APD) by reducing range walk error is presented. Assuming that the creation of primary electrons in the APD is Poisson-distributed, a mathematical model for the detection probability of each time bin in a TOF histogram is derived. It is shown that the range walk error depends on the energy of the laser-return pulse at the Geiger mode APD with the mathematical model regarded as the TOF histogram of multiple laser pulses in a single-hit case. The method which reduces the range walk error with the center of mass detection in the TOF histogram is then proposed, and the experiment for its proof is carried out.     

同步水声跟踪定位系统软件抗距离模糊技术研究

同步水声跟踪定位系统通过时延测量进行定位,当信号传播时延大于脉冲重复周期时,就会出现距离模糊。距离模糊是远程高帧率定位系统不可避免的问题。以往多采用硬件方法抗模糊,使得系统趋于复杂。本文提出了两种软件抗模糊方法:举手表决法和参考位置标示法,前者利用真解的一致性抗模糊,无需任何先验信息;后者利用目标的参考位置抗模糊,需要目标初始就位点这一先验信息。文中给出了算法原理和适用条件。软件抗模糊方法简化了系统设备,海试结果验证了算法的有效性。     

一种宽温双光谱红外搜索跟踪系统的设计

基于谐衍射光学元件特殊的色差和热差特性,将谐衍射元件应用于红外搜索成像系统中, 设计了一个双光谱宽温度范围的红外搜索跟踪成像系统,该系统工作波段为3.7—4.8 μm和8.7—11.3 μm, F数为2.5,有效焦距为200 mm,全视场角为5°, 环境温度为-80 ℃—200 ℃. 设计结果表明,使用谐衍射透镜不仅可以使系统在两个波段范围成像优良, 而且结构简单紧凑、透射比高、具有良好的消热差特性. 关键词： 光谱成像 红外搜索 热差     

Investigations of range accuracy for long-range three-dimensional active imaging

Distance resolutions and noises are analyzed experimentally for long-range three-dimensional (3D) active imaging systems that have signal-to-noise ratios (SNRs) more optimal than 30:1. Findings indicate that the photon shot noise primarily determines the SNR. However, the active imaging method, which has a relatively low SNR, generates a relatively high distance resolution. To explain this phenomenon, a theory in which the distance resolution of 3D active imaging systems is determined by both the photon shot noise and the subinterval width is developed. Theoretical and experimental results differ by less than 4%.