3G无线视频监控系统的设计与实现

随着3G技术的日益成熟和嵌入式技术的飞速发展,数字化视频监控系统将逐步替代传统的模拟视频监控系统,同时随着人们生活质量的提高和活动范围的不断扩大对无线视频监控系统的需求越来越迫切,所以利用3G网络进行实时视频传输必将成为一种趋势。该系统在Linux操作系统下,搭建了一个基于ARM9的视频图像采集环境,并通过CDMA2000网络完成了视频图像的传输接收,实现了远程视频监控的功能。     

基于Linux的无线视频传输系统设计与实现

选用ARM9（S3C2410）处理器为硬件平台,嵌入式Linux操作系统为软件平台,采用WLAN为传输方式,设计并实现了一个无线视频传输系统。提出一个无线视频系统的总框架,介绍系统硬件平台和软件平台的设计与实现,其中主要介绍无线视频系统中的各个模块,包括视频采集模块、无线视频传输模块、视频显示模块。最后验证系统,在接收端可以清楚、连续地显示出发送端所采集到的视频图像。无线视频传输系统可以广泛地应用于视频监控、信息家电、智能小区、远程抄表等领域,而且所研究的嵌入式视频系统设备经过进一步开发和完善,还可以应用于更广阔的领域。     

基于802．11网络的无线视频传输系统设计

提出一种基于S3C2440A硬件平台和嵌入式Linux操作系统的无线视频传输系统设计方案,介绍系统的总体设计和主要功能模块的设计与实现,主要包括视频采集模块、无线视频传输模块的硬件设计,嵌入式Linux的驱动程序移植、MPEG-4数字视频软件压缩以及应用程序实现等。该系统实现了802．11无线局域网内的视频传输,实时监测网络的数据流量和拥塞状况,自动调节视频的压缩比,提高网络传输质量,保证视频播放流畅性,可靠性高且易于使用。     

基于Linux的无线视频监控系统的研究

随着嵌入式技术、图像压缩技术以及无线传输技术的发展,基于嵌入式系统的无线视频监控系统已成为视频监控领域的发展趋势。文章将嵌入式系统的特点与无线传输技术相结合,研究和开发出一种基于Linux的无线视频监控系统。本嵌入式视频监控系统采用C/S架构,服务器基于ARM11处理器,搭载嵌入式Linux系统,主要实现图像的采集、压缩、预览和传输;PC机作为客户端主要实现视频图像的解压、显示以及参数设置等功能。     

基于嵌入式ARM下的视频监控系统的实现

介绍了一种应用于智能家居视频监控系统的实现方案。通过对嵌入式技术的分析和理解,将无线局域网的特点和优势与嵌入式系统相结合,提出并实现了一种无线视频监控的解决方案。该系统以ARMS3C2440为硬件平台,利用Video4Linux2获得USB摄像头采集到的视频图像数据,将其通过UDP协议进行网络传输,最终在PC端的一个基于SDL库设计的程序上进行实时接收并显示。     

嵌入式视频监控系统的设计和实现

近年来,视频监控系统得到了迅速的发展和广泛的应用,将嵌入式技术用于视频监控是其发展的趋势和方向。基于实际的开发需求,设计了一种基于嵌入式Linux的无线视频监控系统,该系统由服务器和客户端两部分组成。服务器通过video4linux接口循环地采集视频并进行MJPEG压缩,然后采用基于802.11g的无线传输协议发送视频。客户端不断地接收视频并进行解码,然后调用SDL在客户端的计算机屏幕上播放监控画面。经测试,该系统实现了视频的实时传输。     

基于i.MX27的无线视频监控系统的设计与实现

介绍了一种以i.MX27为硬件平台的处理器,嵌入式Linux为操作系统的无线视频监控系统的实现方案.给出了系统的总体结构与软硬件模块,重点阐述了视频采集及编码的过程;针对i.MX27硬件编码单元输出的H.264视频流,设计并实现了在RTP协议下视频流的实时传输.客户端通过接收、解码及显示监控前端传送的H.264视频流,实时显示监控场景.经实验测试,该系统达到了较好的实时性和可靠性.     

一种基于ARM的WiFi无线监控系统设计

WiFi以其灵活性强、安装简单、部署成本低等优点,在各个领域得到了广泛的应用。文中介绍了一种以S3C2440A和Linux嵌入式系统为平台环境的远程无线视频监控的实现方法;通过在该平台上建立Web服务将USB摄像头获取到的图像数据通过WiFi无线模块传输到用户端。用以满足家居、办公等室内环境的视频监控的要求。     

基于S3C6410的无线视频监控系统设计与实现

选用S3C6410处理器为硬件平台,嵌入式Linux操作系统为软件平台,对采集到的实时图像进行H264视频编码,通过3G中的分支-wi—fi传输,设计并实现了一个无线视频传输系统。     

基于嵌入式Linux的3G无线视频终端的设计与实现

基于嵌入式系统开发以及3G相关技术,采用ARM+Linux作为软硬件开发平台,充分利用了ARM以及Linux系统丰富的软硬件资源,设计并实现了一个基于嵌入式Linux的3G无线视频终端。在软件设计上,采用了Linux的Netfilter架构与socket结合的方法,引入内核缓冲机制,达到了将数据包获取功能由用户态转入内核态,实现了数据包在Linux内核态的获取及高效转发,并且解决了3G模块因拨号延迟与视频服务器产生速率不匹配所造成的数据丢包问题,同时在嵌入式Linux下为3G模块开发了驱动。     

PMD-induced transmission penalties in polarization-multiplexed transmission

In this paper, we investigate for the first time chromatic dispersion and nonlinearity tolerances in the presence of polarization-mode dispersion (PMD) for polarization-multiplexed (POLMUX) 2 /spl times/ 10-Gb/s nonreturn-to-zero (NRZ) transmission. In polarization-multiplexing, the interaction between fiber nonlinearity and PMD can lower the nonlinear tolerance beyond the tolerances evident when considering both transmission penalties separately; the combined penalties are significantly worse than in the case for non-POLMUX transmission. In this paper, we show, through simulations comparing POLMUX with non-POMUX transmission in the presence of nonlinearity, a reduction of about a factor of three in PMD tolerance. In addition, we show that the dispersion tolerance of POLMUX transmission is severely limited in the presence of PMD. For example, a 40-ps differential group delay (DGD) with worst case coupling of the polarization channels into the fiber lowers the dispersion tolerance, resulting in a 1-dB eye-opening penalty (EOP), from 1200 to 450 ps/nm. We conclude that the interaction between PMD, chromatic dispersion, and nonlinearity leads to the worst signal impairments in POLMUX transmission and increases the effort of using polarization-multiplexing as a modulation format.     

Maximum-likelihood transmission image reconstruction for overlapping transmission beams

In many transmission imaging geometries, the transmitted "beams" of photons overlap on the detector, such that a detector element may record photons that originated in different sources or source locations and thus traversed different paths through the object. Examples include systems based on scanning line sources or on multiple parallel rod sources. The overlap of these beams has been disregarded by both conventional analytical reconstruction methods as well as by previous statistical reconstruction methods. We propose a new algorithm for statistical image reconstruction of attenuation maps that explicitly accounts for overlapping beams in transmission scans. The algorithm is guaranteed to monotonically increase the objective function at each iteration. The availability of this algorithm enables the possibility of deliberately increasing the beam overlap so as to increase count rates. Simulated single photon emission tomography transmission scans based on a multiple line source array demonstrate that the proposed method yields improved resolution/noise tradeoffs relative to "conventional" reconstruction algorithms, both statistical and nonstatistical.     

Dispersion-tolerant transmission using a duobinarypolarization-shift keying transmission scheme

We demonstrate a novel dispersion-tolerant transmission scheme based on a three-level duobinary-encoded polarization-shift keying (PoISK) transmission format. Simulations over standard single-mode fiber demonstrate an improvement in the chromatic dispersion-limited transmission distance from ~65 km, using conventional nonreturn to zero intensity modulation to ~195 km for duobinary PoISK     

Attentive transmission

A simple attention-based model is proposed for efficient transmission of visual information using multiresolution structures. Images are sampled nonuniformly in space and time, such that sampling is dense at the focus of attention and sparse in the periphery (retinal-like). Assuming that the focus of attention usually corresponds to eye position while scanning an image, image features which are “eye catching” (such as sharp edges, motion, and high flicker rate) are used to drive the dense center of sampling. The transmitted image is reconstructed by combining each new sample with previous samplings to give progressive transmission. The selection of sampling points depends only on previously transmitted information, and only sampled values without their location need to be transmitted.     

一种适用于数字视频传输的实时传输协议

网络数字视频监控系统的关键技术之一是视频传输.本文针对网络数字视频监控系统中视频传输的特点,对适用于数字视频传输的实时传输协议进行了研究.在对实时传输协议（RTP）和实时传输控制协议（RTCP）规范进行深入研究的基础上,根据网络数字视频监控系统具体应用的要求,设计了一种称之为“SRTP/SRTCP”的实时数据传输协议,并对该协议进行了具体实现.     

Optimal transmission of high definition video transmission in WiMedia systems

WiMedia systems are developed for indoor high-data-rate wireless systems. The H.264/AVC, a high-efficiency video coding technique, is considered for high definition (HD) video application. Considering the transmission of H.264/AVC based HD video over WiMedia, in this paper, we will propose a cross-layer architecture and an analytical model to calculate the optimal payload length with the constraints in error criteria, retransmission mechanism, and the delay budget. Besides, the required minimum reservation slots in WiMedia are also investigated to optimize the transmission performance of HD video.     

Sustainable image transmission

Under the assumption of oscillatory behaviour of the difference between coding gain and transmission cost over time, heavy losses may be incurred in the form of foregone transmission opportunities in the future or in the present. It calls for a sustainable transmission path which would then modify the optimal transmission condition accordingly to render it dynamically efficient over time.But what is the most sustainable transmission path? Sustainable transmission satisfies the needs for transmission at present time without compromising the needs of bits for future transmission.This paper presents a set of axioms that capture this idea of sustainable transmission and characterizes the criterion of sustainable transmission. The Pontryagin’s maximum principle is then used to find out the transmission path that maximizes such a criterion. It will be the most sustainable transmission path.Here we analyze to which point three coding methods lead to sustainable transmission.     

Metal-insulator-semiconductor transmission lines

This paper investigates the one-dimensional metal-insulator-semiconductor transmission line. It develops closed-form expressions for equivalent-circuit parameters, compares them to exact calculations, and explores their limitations. It also investigates the usual assumption of single-mode propagation and shows that, in certain fairly common circumstances, the fundamental mode of propagation becomes so lossy that it can no longer be considered to be the dominant propagating mode     

Flexible AC transmission

The operation and components of the flexible AC transmission system (FACTS) are described. FACTS, designed to overcome the limitations of the present mechanically controlled AC power transmission systems, uses reliable, high-speed power electronic controllers. Its benefits are examined. These include greater control of power, so that it flows on the prescribed transmission routes; secure loading of transmission lines to levels nearer their thermal limits; greater ability to transfer power between controlled areas, so that the generation reserve margin may be reduced; prevention of cascading outages by limiting the effects of faults and equipment failure; and damping of power system oscillations