An audio and video network monitoring system for weather modification operation transmitting information by 3G, ADSL and Internet has been developed and applied in weather modification operation of Tai＇an City. The a...An audio and video network monitoring system for weather modification operation transmitting information by 3G, ADSL and Internet has been developed and applied in weather modification operation of Tai＇an City. The all-in-one machine of 3G audio and video network highly integrates all front-end devices used for audio and video collection, communication, power supply and information storage, and has advantages of wireless video transmission, clear two-way voice intercom with the command center, waterproof and dustproof function, simple operation, good portability, and long working hours. Compression code of the system is transmitted by dynamic bandwidth, and compression rate varies from 32 kbps to 4 Mbps under different network conditions. This system has forwarding mode, that is, monitoring information from each front-end monitoring point is trans- mitted to the server of the command center by 3G/ADSL, and the server codes＇and decodes again, then beck-end users call images from the serv- er, which can address 3G network stoppage caused by many users calling front-end video at the same time. In addition, the system has been ap- plied in surface weather modification operation of Tai＇an City, and has made a great contribution to transmitting operation orders in real time, monitoring, standardizing and recording operating process, and improving operating safety.展开更多
Over the past years, we have witnessed an explosive growth in the use of multimedia applications such as audio and video streaming with mobile and static devices. Multimedia streaming applications need new approaches ...Over the past years, we have witnessed an explosive growth in the use of multimedia applications such as audio and video streaming with mobile and static devices. Multimedia streaming applications need new approaches to multimedia transmissions to meet the growing volume demand and quality expectations of multimedia traffic. This paper studies network coding which is a promising paradigm that has the potential to improve the performance of networks for multimedia streaming applications in terms of packet delivery ratio (PDR), latency and jitter. This paper examines several network coding protocols for ad hoc wireless mesh networks and compares their performance on multimedia streaming applications with optimized broadcast protocols, e.g., BCast, Simplified Multicast Forwarding (SMF), and Partial Dominant Pruning (PDP). The results show that the performance increases significantly with the Random Linear Network Coding (RLNC) scheme.展开更多
天地视频/音频通信在载人航天任务中具有重要的作用。为实现天地视频/音频通信,针对载人航天器与地面通信站之间通信链路时延长和前向/返向链路速率不对称的特点,提出一种天地视频/音频通信网络一体化设计。采用国际空间数据系统咨询委...天地视频/音频通信在载人航天任务中具有重要的作用。为实现天地视频/音频通信,针对载人航天器与地面通信站之间通信链路时延长和前向/返向链路速率不对称的特点,提出一种天地视频/音频通信网络一体化设计。采用国际空间数据系统咨询委员会(CCSDS)的IP技术(IP over CCSDS技术)实现视频/音频数据天地一体化传输;针对不同类型、不同优先级的数据,采用静态优先级和轮询调度策略相结合的调度方式,以保证业务传输需求。采用信道编码、加扰和加同步字的方式,保证天地视频/音频传输的服务质量(QoS)。文章提出的天地视频/音频通信网络一体化设计,经过地面试验和在轨飞行验证,结果表明:视频数据传输速率均匀,图像话音清晰无卡顿,均未发生丢包,可用于低轨载人航天器与地面站的通信,也可为后续载人登月、载人登火等深空领域任务提供参考。展开更多
航空电子网络上音视频应用的需求日益剧增,对网络的带宽及服务质量都提出了更高的要求。音视频传输AVB(Audio Video Bridge)以太网络在传统以太网上提供时间同步和低延迟的音视频流服务,因而受到航电应用的关注。分析了AVB协议,针对航...航空电子网络上音视频应用的需求日益剧增,对网络的带宽及服务质量都提出了更高的要求。音视频传输AVB(Audio Video Bridge)以太网络在传统以太网上提供时间同步和低延迟的音视频流服务,因而受到航电应用的关注。分析了AVB协议,针对航电环境下信息交换需解决的问题,提出了时间触发AVB网络方案,研究了其实时性传输机制和流量映射等模型;结合某综合航电系统的案例,构建了AVB网络的系统架构,仿真结果表明时间触发AVB网络有望满足分布式综合模块化航空电子(DIMA)系统实时性需求,并且比AFDX网络具有优越性。展开更多
基金Supported by the Integration and Application Project of Meteorological Key Technology of China Meteorological Administration(CMAGJ2012M30) Technology Development Projects of Tai'an Science and Technology Bureau in 2010 (201002045) and 2011
文摘An audio and video network monitoring system for weather modification operation transmitting information by 3G, ADSL and Internet has been developed and applied in weather modification operation of Tai＇an City. The all-in-one machine of 3G audio and video network highly integrates all front-end devices used for audio and video collection, communication, power supply and information storage, and has advantages of wireless video transmission, clear two-way voice intercom with the command center, waterproof and dustproof function, simple operation, good portability, and long working hours. Compression code of the system is transmitted by dynamic bandwidth, and compression rate varies from 32 kbps to 4 Mbps under different network conditions. This system has forwarding mode, that is, monitoring information from each front-end monitoring point is trans- mitted to the server of the command center by 3G/ADSL, and the server codes＇and decodes again, then beck-end users call images from the serv- er, which can address 3G network stoppage caused by many users calling front-end video at the same time. In addition, the system has been ap- plied in surface weather modification operation of Tai＇an City, and has made a great contribution to transmitting operation orders in real time, monitoring, standardizing and recording operating process, and improving operating safety.
文摘Over the past years, we have witnessed an explosive growth in the use of multimedia applications such as audio and video streaming with mobile and static devices. Multimedia streaming applications need new approaches to multimedia transmissions to meet the growing volume demand and quality expectations of multimedia traffic. This paper studies network coding which is a promising paradigm that has the potential to improve the performance of networks for multimedia streaming applications in terms of packet delivery ratio (PDR), latency and jitter. This paper examines several network coding protocols for ad hoc wireless mesh networks and compares their performance on multimedia streaming applications with optimized broadcast protocols, e.g., BCast, Simplified Multicast Forwarding (SMF), and Partial Dominant Pruning (PDP). The results show that the performance increases significantly with the Random Linear Network Coding (RLNC) scheme.
文摘天地视频/音频通信在载人航天任务中具有重要的作用。为实现天地视频/音频通信,针对载人航天器与地面通信站之间通信链路时延长和前向/返向链路速率不对称的特点,提出一种天地视频/音频通信网络一体化设计。采用国际空间数据系统咨询委员会(CCSDS)的IP技术(IP over CCSDS技术)实现视频/音频数据天地一体化传输;针对不同类型、不同优先级的数据,采用静态优先级和轮询调度策略相结合的调度方式,以保证业务传输需求。采用信道编码、加扰和加同步字的方式,保证天地视频/音频传输的服务质量(QoS)。文章提出的天地视频/音频通信网络一体化设计,经过地面试验和在轨飞行验证,结果表明:视频数据传输速率均匀,图像话音清晰无卡顿,均未发生丢包,可用于低轨载人航天器与地面站的通信,也可为后续载人登月、载人登火等深空领域任务提供参考。
文摘航空电子网络上音视频应用的需求日益剧增,对网络的带宽及服务质量都提出了更高的要求。音视频传输AVB(Audio Video Bridge)以太网络在传统以太网上提供时间同步和低延迟的音视频流服务,因而受到航电应用的关注。分析了AVB协议,针对航电环境下信息交换需解决的问题,提出了时间触发AVB网络方案,研究了其实时性传输机制和流量映射等模型;结合某综合航电系统的案例,构建了AVB网络的系统架构,仿真结果表明时间触发AVB网络有望满足分布式综合模块化航空电子(DIMA)系统实时性需求,并且比AFDX网络具有优越性。
