图像式头盔瞄准具定位模型研究与仿真

随着虚拟现实与仿真技术的发展,头盔瞄准技术越来越多地应用于战斗机和直升机地面飞行模拟训练和实际作战。通过对单目视觉测量方法和四点定位模型的分析,论述了图像式头盔瞄准具的系统结构及工作机理,着重讨论了定位模型方程解的结构以及错误解的排除等关键问题。设计了头盔瞄准仿真平台,使用VC开发环境与Open-GL相结合导入3dmax模型,设置投影模型参数与相机标定参数一致,仿真相机成像过程,完成了系统组成结构和工作过程的仿真与模拟。仿真实验证明该模型能够完成目标的精确定位,可供从事头盔瞄准具设计和系统综合的工程师参考。     

头盔CRT显示部件互换性技术

头盔CRT显示部件互换性技术解决了显示部件差异性影响头盔组件互换性的问题,该技术以头盔实用性和互换性为标准,分析各个显示部件对头盔互换性的影响程度。通过更换各显示部件,对显示画面的中心位置、畸变、增益、亮度、聚焦等数据进行测量和分析,找出影响头盔互换性的最大因素,最终提出解决CRT互换性的方法,设计和评定CRT的一致性指标。通过实验证明实现头盔组件的互换性,进一步提高头盔显示系统的实用性和维护性。     

无线电定位技术在蜂窝通信系统中的应用及实现

当前,移动用户对基于无线定位技术的新业务的需求不断增加,推动了对无线测距及定位技术的深入研究,向用户提供精确的定位信息已经成为新一代PCS系统的标准业务之一。主要介绍几种基于现有蜂窝通信系统的无线定位技术的实现原理,所要解决的主要问题和应用前景。     

火控光电瞄准系统在惯导校正中的应用

充分，合理利用现有机载设备的信息资源来提高导航精度和可靠性是一项非常值得研究的课题，根据某型飞机火控光电瞄准系统中头盔瞄准具的测角原理和激光测距机的斜距信息，提出了用其校正惯导航向和位置坐标和数学模型，并对其应用作了进一步的讨论，此结论对于其它机地航信息的融合也具有一定的借鉴价值。     

基于散射体信息的双基站定位

该文基于单次散射移动通信模型,利用双基站测得的多条散射路径的到达时间(TOA)和到达角度(AOA)进行定位,提出了一种非直达波条件下的高精度移动定位算法,仿真结果验证了该算法的有效性。     

Performance of terahertz channel with multiple input multiple output techniques

Terahertz (THz) communication is being considered as a potential solution to mitigate the demand for high bandwidth. The characteristic of THz band is relatively different from present wireless channel and imposes technical challenges in the design and development of communication systems. Due to the high path loss in THz band, wireless THz communication can be used for relatively short distances. Even, for a distance of few meters (>5m), the absorption coefficient is very high and hence the performance of the system is poor. The use of multiple antennas for wireless communication systems has gained overwhelming interest during the last two decades. Multiple Input Multiple Output (MIMO) Spatial diversity technique has been exploited in this paper to improve the performance in terahertz band. The results show that the Bit Error Rate (BER) is considerably improved for short distance (<5m) with MIMO. However, as the distance increases, the improvement in the error performance is not significant even with increase in the order of diversity. This is because, as distance increases, in some frequency bands the signal gets absorbed by water vapor and results in poor transmission. Adaptive modulation scheme is implemented to avoid these error prone frequencies. Adaptive modulation with receiver diversity is proposed in this work and has improved the BER performance of the channel for distance greater than 5m.     

Harris Hawk Optimization Algorithm‐based Effective Localization of Non‐Line‐of‐Sight Nodes for Reliable Data Dissemination in Vehicular Ad hoc Networks

Vehicular Ad hoc NETwork (VANET) is considered as the appropriate candidate for provisioning risk‐free environment that confirms secure cooperation and very minimal congestion among the vehicular nodes in the network. The establishment and maintenance of connectivity between vehicular nodes are determined to be influenced by the existence of Non‐Line‐of‐Sight (NLOS) nodes that introduce channel congestion and broadcasting storm into the network during emergency message delivery. Thus, NLOS nodes need to be localized with optimality for enhancing the emergency data delivery rate with minimized latency degree and energy consumption in the network. In this paper, Harris Hawk Optimization Algorithm (HHOA)‐based NLOS nodes Localization Scheme (NLOS‐LS) (HHOA‐NLOS‐LS) is proposed for facilitating reliable data dissemination among vehicular nodes under emergency situations. HHOA utilizes chasing styles and cooperative behavior of Harris hawks termed as surprise pounce for efficient localization based on reference nodes. In particular, the intelligent strategy of Harris hawks' behavior in attacking the prey in all directions is included for localizing the NLOS nodes from the reference nodes positioned in all directions of the network. It is capable of localizing the NLOS nodes based on adaptive localizing (chasing) styles attained through reference nodes dependingon the dynamic nature of NLOS nodes. The simulation results prove that the mean localization rate is improved by 23.21%, mean neighborhood awareness rate by 19.82%, mean emergency message delivery rate by 18.32% and mean channel utilization by 17.28% when compared to the baseline Weighted Inertia‐based Dynamic Virtual Bat Algorithm (WIDVBA)‐based NLOS‐LS (WIDVBA‐NLOS‐LS), Cooperative Volunteer Vehicular Nodes (CVVN)‐based NLOS‐LS (CVVN‐NLOS‐LS), Vote Selection Mechanisms and Probabilistic Data Association (VSMPDA)‐based NLOS‐LS (VSMPDA‐NLOS‐LS), and Weighted Distance Hyperbolic Prediction (WDHP)‐based NLOS‐LS (WDHP‐NLOS‐LS) for a varying number of vehicular nodes in the network.