甚高频（VHF）在飞机中的应用

随着航空电子的飞速发展,甚高频通信系统功能日渐增多、越发强大。目前,甚高频通信系统仍然是现在飞机中非常重要的通信手段。因为技术的不断发展、技术的不断提高,经验的不断积累与沉淀,甚高频系统现在已经更加成熟,架构余度也很大,安全性能也在日渐提高,操作也简单。本文从甚高频地空数据通讯系统的功能与架构分析出发,结合国内外实际情况对甚高频在飞机中的各方面应用进行了探索。     

甚高频(VHF)在飞机中的应用

随着航空电子的飞速发展,甚高频通信系统功能日渐增多、越发强大。目前,甚高频通信系统仍然是现在飞机中非常重要的通信手段。因为技术的不断发展、技术的不断提高,经验的不断积累与沉淀,甚高频系统现在已经更加成熟,架构余度也很大,安全性能也在日渐提高,操作也简单。本文从甚高频地空数据通讯系统的功能与架构分析出发,结合国内外实际情况对甚高频在飞机中的各方面应用进行了探索。     

GMDSS现代化背景下海上通信技术发展概述

本文在介绍国际海事组织和国际海上人命安全公约的基础上,引出全球海上遇险与安全系统（GMDSS）诞生的历史背景及其现代化进程,详细说明了包括国际移动卫星系统、铱星系统和北斗报文服务系统在内的三个获得国际海事组织批准纳入GMDSS的卫星通信系统现状,同时介绍了甚高频数据交换系统和水上中频安全信息数字广播系统及其被引入GMDSS的相关进展情况。     

机载甚高频ACARS数据链系统及通信管理单元设计

装备通信管理单元、甚高频电台等机载设备的飞机具备接入飞机通信寻址与报告系统(ACARS)地空数据网络的能力.分析了甚高频ACARS数据链机载系统的结构,探讨了通信管理单元的服务功能和应用功能,基于通信管理单元与甚高频数传电台、机上系统以及驾驶舱之间的接口和协议,设计了实现ACARS协议的通信管理单元的软件结构模型.     

浅析甚高频远程监控系统（RCMS）的设计改进

近年来,甚高频远程监控系统(RCMS,Remote Control Monitor System)技术被广泛应用于空管甚高频天线共用系统中。甚高频远程监控系统通过对甚高频电台参数及硬件模块正常与否的实时监控为基础,通过人机界面维护人员可以方便地检查系统状态,并对电台的频率、发射功率、调制度、静噪门限等重要参数进行修改。大幅提高了维护维修人员的工作效率,降低了因设备故障因素影响安全运行及管制业务。本文通过分析近年来空管系统在用的厂家配套甚的高频系统远程监控系统(RCMS)功能的不足,结合实际运行维护工作中的一些思路,优化完善核心功能,从而能够达到预防性维护维修的工作要求。     

民航甚高频地空通信干扰对策研究

在我国民航系统不断壮大背景下,加强民航系统运行质量具有重要意义。本文主要针对民航甚高频地空通信进行研究与分析,在分析民航甚高频地空通信发展现状的基础上,指出我国民航甚高频地空通信管理的重要性以及存在的问题,针对问题提出甚高频地空通信干扰优化策略。     

浅析甚高频数据交换系统

随着软件无线电技术的发展、E-航海概念的引入,使航运业对水上无线电通信数字化、高速化、宽带化的要求越来越高,甚高频数据交换系统(VDES)是国际航标协会航海委员会提出的,VDES对于海上信息服务有重要意义,包括海上救援和海上交通,是E-航海的关键所在.本文通过研究国际重要会议的相关提案,对VDES的提出背景、组成内容及实施路线进行了整理阐述.     

民航甚高频地空数据链地面站优化设计

现有民航甚高频地空数据链通信系统数据源面向用户封闭、无法二次开发,难以满足大飞机研制阶段的验证测试要求。通过分析现有民航甚高频地空数据链的报文处理流程,对地空数据链地面站系统功能进行划分。以满足地空通信协议规范和用户需求为出发点,提出了甚高频地空数据链的优化思想,总结了所需解决的三个问题:算法复杂度评估、硬件数据交互实现、数据管理。文中着重对地面站系统中的解调算法和数据交互方案进行评估,最后给出了优化设计方案。     

甚高频通信互调干扰分析及对策

随着我国科学技术的不断发展,各行业应用的通信技术水平也日益提升,通信质量显著提高.无线电技术是当前最为先进的科学技术,在领域内得到广泛应用,但是无线技术的应用环境日趋复杂,对相关工作的开展造成了不利影响,也降低了甚高频通信系统的稳定性.对此,本文首先对无线电对甚高频通信的影响进行分析,其次阐述了甚高频通信系统无线干扰类型进行总结,然后提出甚高频通信系统可靠性提升措施,为相关人士提供参考.     

空管甚高频综合管理系统的设计与实现

我国民用航空事业的快速发展,导致原有的民航用甚高频的频率和设备数量已不能满足使用需求,近些年来民航甚高频频率和设备量都在以极大的数量增长,对频率的使用和管理带来了诸如:频率串扰,设备维护数据庞大,维护数据跟踪困难,路由资料缺漏等众多问题。在详细分析了本地区民用航空甚高频产生的频率串扰原因,对管理室范围内分散的甚高频频率和设备进行集中高效的管理需求基础上,利用运用SQL SERVER数据库和Visual C#2010集成开发工具,自行研发一套贴合实际应用的空管甚高频频率以及甚高频地空通信设备管理系统。系统自投入使用半年多以来,运行稳定,使用方便快捷,为值班人员提供了解决频率串扰问题的有效工具,并且极大地提高了本管理室对于甚高频频率管理的效率。     

Review of antenna technologies for very high frequency Data Exchange Systems

The Automated Identification System (AIS) was originally developed as a terrestrial system tracking vessels near the coastline. Dedicated channels were allocated within the spectrum historically reserved for maritime applications in the very high frequency (VHF) band, enabling long range communications, up to a few kilometers. There have been various initiatives in the last decade that extended this system with a space segment, enabling global monitoring of vessels beyond the range of terrestrial stations. Recently, the World Radiocommunication Conference has allocated frequencies for the extension of this system to a two-way VHF Data Exchange System (VDES) via satellite. This requires to adapt spaceborne antenna solutions previously developed for AIS, particularly for missions using small satellites and CubeSats. This paper provides a timely review of existing VHF antenna solutions and new concepts under development which could be applicable to VDES missions. Some key metrics are identified to provide a comparative study between various candidate solutions. Considering the range of possible missions, from secondary payloads on-board larger satellites to dedicated constellations, it is believed that a number of antenna products can find application in future VDES space-based infrastructure.     

Performance Specifications for the Roll-Off Factor and Filter Order for Filtered Multitone Modulation in the Maritime VHF Data Exchange System

Mobile Networks and Applications - The Maritime VHF Data Exchange System (VDES) will be a basic method of data exchange in the e-Navigation strategy, which has been developed by the International...     

VDES R-Mode performance analysis and experimental results

Global Navigation Satellite Systems (GNSS) have become an essential part of maritime navigation, in particular to improve situational awareness and vessel traffic management. The dependence on GNSS creates vulnerability for maritime shipping. Driven by this vulnerability, the desire for a backup system for maritime navigation has been emerging. The VHF Data Exchange System (VDES) standard provides communication capabilities for maritime applications. VDES is currently being revised. As part of this revision, VDES will be extended by ranging and navigation functionalities, called R-Mode, as an alternative for maritime navigation. In this paper, we address system design aspects and evaluate the positioning performance of VDES R-Mode. We derive estimation theory bounds on the accuracy of VDES R-Mode distance and velocity. In a case study, we discuss and evaluate the benefit of satellite links to complement VDES R-Mode positioning. Furthermore, we introduce a Kalman filter for position and velocity tracking, which we apply to experimental data. We describe an experiment we conducted at Lake Ammer, southwest of Munich, and evaluate the VDES R-Mode positioning performance for this setup. Our experimental results show that VDES R-Mode is capable of achieving a 95th-percentile horizontal position error of 22 m. Thus, VDES R-Mode is a promising approach for a maritime backup system that can meet the IALA accuracy requirements.     

基于OFDM的VDES地面子系统设计

为解决海上远距离通信给甚高频数据交换系统（VDES）地面子系统带来的严重多径干扰,将正交频分复用（OFDM）技术融入VDES 地面子系统,在协议框架下完成对系统物理层时隙结构的设计,利用OFDM 技术优越的抗多径性能解决VDES 地面子系统存在的严重多径干扰问题。首先,在VDES 地面子系统基础框架下,设计融合了OFDM 技术的VDES 地面子系统完整底层链路系统,并确保各子模块基础性能不差于建议书提供的需求指标。然后,利用MATLAB 软件对系统开展了在逼近循环前缀（CP）大小的极限时延下多径信道环境的仿真测试,结果表明在大时延多径信道环境下系统仍具有很好的抗多径性能,且传输速率略高于当前VDES 标准协议参数。最后,完成了系统的硬件设计并于大连海域完成海上实测,系统最大极限空口速率可达312.7 kbit/s。研究表明,把OFDM 技术引入到VDES 系统,对于帮助VDES 系统对抗多径干扰,提升系统稳健性有相当重要的作用,这也是VDES 系统发展需要探索的方向之一。     

Satellite forward VDES channel modeling and impact on higher-layer performance

VHF data exchange system (VDES) is an emerging maritime communications standard that is meant to provide ship-to-shore, shore-to-ship, and ship-to-ship information services. VDES also includes a satellite component to extend the service coverage also to the high sea. Ships can receive important information via VDES and access this service via satellite when they are far from the shore. This paper uses data taken during a measurement campaign to develop an ON-OFF model for the VDE-SAT downlink channel taking the multipath effects caused by sea reflections into account. This model has been used to evaluate the impact of packet-level forward error correction (FEC) schemes (i.e., ideal codes, RaptorQ codes, and 2-Dimension Reed-Solomon codes) to further protect transmissions from deep fading events and to evaluate the impact at the transport level considering the possibility to adopt the transmission control protocol (TCP) for a file map delivery service.     

Performance bounds for VDE-SAT R-Mode

There has been growing interest within the satellite navigation community in the possibility of delivering positioning and timing services from existing or emerging constellations of Low-Earth Orbit communication satellites. At the same time, the international maritime community has been investigating the potential use of communication signals transmitted from shore-based stations for positioning—a concept commonly referred to as ‘ranging mode’, or R-Mode. The driving force for these developments is the desire to reduce the reliance on traditional Global Navigation Satellite Systems (GNSS). One of the technologies being considered for use in R-Mode is the evolution of the Automatic Identification System (AIS) known as the Very High Frequency Data Exchange System (VDES). VDES has a terrestrial and a satellite component. The feasibility of using terrestrial VDES transmissions for ranging was studied in a previous publication by the authors. This paper builds on the previous study and extends its results to the satellite component of VDES. Statistical bounds on the ranging error are derived for all downlink waveforms currently being considered for use in satellite VDES and for several custom-designed transmission formats. The analysis supports the feasibility of using both the existing and custom waveforms in ranging applications and points to related trade-offs that will need to be considered in the design of satellite VDES R-Mode systems.     

一种船舶自动识别系统甚高频信道的低成本设计

随着船舶自动识别系统(AIS)市场竞争的日益激烈,低成本化是AIS产品研制的必然趋势。根据国际海事组织(IMO)有关标准,给出了一种AIS甚高频(VHF)信道的低成本设计方案。介绍了AIS工作原理及其VHF信道的工作过程,给出了简洁实用的发射机和接收机设计,并对调制器、VHF功放、解调器等核心单元设计方法、器件选择进行了详细阐述。测试和外场实用表明该VHF信道各项指标均已达到规定要求,并且该VHF信道硬件成本低,性能可靠。     

基于安全性评估的民用客机VHF通信电台架构

进行设备级的安全性评估是民用客机VHF通信电台适航审定的要求。简述了机载系统和设备的安全性评估指南、方法及过程,描述了VHF通信电台各组成模块的失效模式及失效率,并运用SAEARP4761所推荐的故障树方法估算出了单通道架构VHF通信电台的失效概率,估算结果说明单通道架构VHF通信电台不能满足飞机级PSSA(Preliminary System Safety Assessment)分配的失效概率要求。最后,为了降低VHF通信电台的失效概率,提出了VHF通信电台的非相似多通道实现架构。分析表明,与单通道架构相比,非相似多通道实现架构的VHF通信电台具有更低的失效概率。     

VDES R-Mode: Vulnerability analysis and mitigation concepts

VDES R-Mode aims at providing a contingency maritime positioning and navigation system when the operation of Global Navigation Satellite Systems (GNSS) is disrupted. However, VDES R-Mode, similarly to GNSS, can itself also be subject to different types of attacks, such as jamming or spoofing. In this paper, we evaluate the vulnerabilities of VDES R-Mode and discuss the effectiveness and cost of different types of countermeasures. The outcome of this cost-benefit analysis is a recommendation to introduce authentication for the navigation messages of R-Mode using the Timed Efficient Stream Loss-Tolerant Authentication (TESLA) protocol.     

Application of cognitive radio and interference cancellation in the L-Band based on future air-to-ground communication systems

The Very High Frequency band (VHF) currently used for aeronautical communications is becoming congested, and future Air-to-Ground (A/G) communication will require much greater use of data communications. For meeting future capacity requirements in aeronautical communications, we propose two new approaches one of which is a cognitive radio based A/G communication network that provides dynamic spectrum access to airplanes to overcome the spectrum scarcity problem in the VHF band. Another approach involves use of a new spectrum in the Ultra-High Frequency band (UHF) to create a new A/G link. In this paper, we propose and investigate the possibilities for developing a spectrum sensing approach to detect idle band in the VHF spectrum and analyze the possible interference between future L-band Digital Aeronautical Communication System (L-DACS) and legacy aeronautical systems.