Broadband video distribution over passive optical network using subcarrier multiplexing techniques

A 16-channel subcarrier-multiplexed video system has been optimised for operation over a passively split optical network. The system delivers a weighted SNR of 47 dB with an optical power budget of 34 dB and a dynamic range of 19 dB.<>     

Optical time-division multiplexing signal processing using electro-optic modulators

We present some optical signal processing methods for optical time-division multiplexing, based on electro-optic modulators. Dual-parallel Mach–Zehnder modulator and time-lens-based signal processing for optical frequency comb generation, optical Nyquist pulse generation and time-domain demultiplexing are realized. Multifunctional optoelectronic oscillators which are capable of performing simultaneous electrical clock recovery, optical clock recovery and demultiplexing are demonstrated with modulators embedded as the key components.     

Multichannel video and IP signal multiplexing system using CWDM technology

This paper describes how coarse wavelength-division multiplexing can realize a multiplexed multichannel video and Internet protocol (IP) system. In the proposed configuration, each signal is optically amplified separately to extend the service area. The IP signals are boosted by cost-effective erbium-doped fiber amplifiers, which have a simple configuration optimized for single-channel use. Two multiplexer/demultiplexer configurations are described. The proposed configurations yield a contents distribution network that offers bidirectional IP service in addition to the multichannel video service, which is transmitted as an analog signal. This paper presents an experiment that confirms the feasibility of this proposed system.     

Optical amplifiers for video distribution

The promise of a broadband fibre communications network has attracted the interest of CATV and Telco concerns. Various networks and topologies have been discussed. Cost is a drawback in some of the proposed networks, particularly those networks which require switching. This paper discusses a low cost broadcast tree and branch network which uses optical amplifiers to extend the network penetration. Recent work in the development of optical amplifiers suggests that the Erbium fibre amplifier may be compatible with VSB-AM. The characteristics of such an amplifier will be discussed. This scenario allows an orderly transition from the present-day AM backbone system to the tree and branch fibre architecture. Once the broadband fibre plant is in place new services can be implemented that exploit the broadband nature of fibre.     

Performance evaluation of digital and analogue video distribution systems using coherent subcarrier multiplexing

Compares digital and analogue approaches for broadband distribution of video signals using a coherent subcarrier multiplexed architecture. The analysis shows that FM is most attractive for near-term applications because it offers very good receiver sensitivity and high channel capacity.<>     

可任意扩展的视音频切换器设计

介绍了手选和自动顺序切换均可任意扩展的视音频切换电路。解决了CD4017在链接中的计数脉冲定向。复位后补发脉冲等问题，使是自动顺序切换的通道数也可任意扩展。     

107-gb/s optical signal generation using electronic time-division multiplexing

This paper reports the first optical transmitter implementations operating at a serial bit rate of 107 Gb/s using solely electronic time-division multiplexing. Two methods to overcome modulator bandwidth limitations are proposed and demonstrated: low-bandwidth optical duobinary modulation and integrated optical equalization. Both transmitters are characterized in terms of bit error ratio and chromatic dispersion tolerance.     

视频会议系统中音频IP多播在局域网上的实现

介绍了一个模拟视频会议的流程设计和一个实用的利用Socket进行多播通信的实现流程,以在局域网上实现音频IP多播为例,说明多播技术的应用及其实现方法。     

带有可编程视频接口单元的单芯片MPEGⅡ视音频编解码器SM2288

1.概述 美国视讯科技有限公司(Stream Machine)公司所推出的低成本,高性能,单芯片的MPEG-2音频视频编解码产品,是由一个RISC(精简指令集运算)芯核,一个24位DSP(数字信号处理器),视频音频接口单元及多个专用处理单元组成。该产品的可编程视频接口单元对多模式的前,后处理及OSD(屏幕显示)有着强大的支持功能。其CODEC(多媒体数字信号编解码器)更是采用了0.18微米CMOS工艺技术的标准信元库。     

改进的TD网Iu接口光信号采集卡的硬件设计

文章主要介绍时分同步码分多址(TD-SCDMA)网络Iu接口光信号采集板卡的研究现状和基本原理.通过与传统采集卡的对比分析,提出一种改进的采集板卡的设计方案,并对采集板卡硬件系统的各组成部分进行了简要的分析和介绍.最后对硬件调试的基本原理作了概括.     

Optical coherent broad-band transmission for long-haul anddistribution systems using subcarrier multiplexing

Signal multiplexing techniques for coherent optical transmission are compared, and appropriate application for a coherent subcarrier multiplexing (SCM) system is discussed. Optical frequency modulation (FM) using direct modulation of a distributed-feedback laser diode (DFB-LD) and a heterodyne detection is shown to be feasible. A transmission system using a local laser in the transmitter is unaffected by polarization and is cost effective. Phase noise can be suppressed by a phase-noise-canceling circuit (PNC) in a heterodyne receiver. This circuit can also effectively compensate for the frequency of instability of light sources. A theoretical simulation of a coherent SCM system showed that 100 channels of 30-MHz FM signal or 15 channels of 155-Mb/s signal can be distributed to 10000 subscribers using single-stage or double-stage optical amplifiers     

64 kbit/s audio signal transmission approaches using 32 kbit/sADPCM channel banks

Two simple 64-kb/s wideband coding approaches using 32-kb/s ADPCM (adaptive digital pulse-code modulated) channel banks are proposed and compared to CCITT 64 kb/s ADPCM, which is being recommended as CCITT G.722. These two, folding ADPCM and QMF ADPCM, are intended to pave the way for smooth transition from conventional 4-kHz band telephone systems to 7-kHz wideband systems in private networks. The first approach, supporting the high-quality audio program transmission, requires only samplers and multiplexers at the input and output ports of the channel banks. In the second approach, samplers and multiplexers are replaced by quadrature mirror filters in order to increase coding quality. Performance test results for audio signal transmission show that these simplified approaches provide an inexpensive way to introduce wideband communication systems     

基于WDM/OCDMA-PON的光纤无线混合接入网结构

通过分析波分多址技术、码分多址技术的PON光纤接入技术和宽带无线技术相结合的混合光纤无线接入网技术的优越性和可行性,提出了基于WDM/OCDMA-PON光纤无线混合(HOWBAN)接入网技术的基本结构,给出WDM/OCDMA-PON光纤无线混合接入网系统的实现方案,提出了应用前景等.     

Radar signal categorization using a neural network

Neural networks are used to analyze a complex simulated radar environment which contains noisy radar pulses generated by many different emitters. The neural network used is an energy-minimizing network. The limiting process contains the state vector within a set of limits, and this model is called the brain state in a box, or BSB model, which forms energy minima (attractors in the network dynamical system) based on learned input data. The system first determines how many emitters are present (the deinterleaving problem). Pulses from individual simulated emitters give rise to separate stable attractors in the network. Once individual emitters are characterized, it is possible to tentatively identify them based on their observed parameters. As a test of this idea, a neural network was used to form a small database that could potentially make emitter identification. There were three errors of classification. The number of iterations are required to reach an attractor state was very long, and some of the final states were not fully limited. These factors indicate the uncertainty of the neural network     

Optical computing techniques for image/video compression

The advantage of optics is its capability of providing highly parallel operations in a three-dimensional space. In this paper, we propose optical architectures to execute various image compression techniques. We optically implement the following compression techniques: transform coding, vector quantization, video coding. We show many generally used transform coding methods, for example, the cosine transform, can be implemented by a simple optical system. The transform coding can be carried out in constant time. Most of this paper is concerned with an innovative optical system for vector quantization using holographic associative matching. Limitations of conventional vector quantization schemes are caused by a large number of sequential searches through a large vector space. Holographic associative matching provided by multiple exposure holograms can offer advantageous techniques for vector-quantization-based compression schemes. Photorefractive crystals, which provide high-density recording in real time, are used as our holographic media. The reconstruction alphabet can be dynamically constructed through training or stored in the photorefractive crystal in advance. Encoding a new vector can be carried out by holographic associative matching in constant time. An extension to interframe coding using optical block matching methods is also discussed     

WDM ring network using a centralized multiwavelength light sourceand add-drop multiplexing filters

We propose and experimentally demonstrate a wavelength division multiplexed (WDM) ring network employing a centralized multiwavelength light source to supply all nodes with optical carriers of precise wavelength spacing. This approach overcomes the problem of monitoring and controlling the wavelengths of optical sources dispersed throughout the network. A four-node test bed using optical lattice-type add-drop multiplexing filters and a multiwavelength light source based on resonant cavity-enhanced four wave mixing in a Fabry-Perot laser diode was constructed to demonstrate the feasibility of the proposed method. The effects of coherent crosstalk in such networks are analyzed, and methods such as phase scrambling or the use of a pulsed optical source are shown to significantly reduce the effects of coherent crosstalk. The use of four-port add-drop multiplexer (ADM) filters instead of 1:n optical wavelength multiplexer/demultiplexers to implement the wavelength add-drop function at each node is shown to lead to a broader transmission bandwidth for each channel and also easier compatibility with the coherent crosstalk suppression mechanisms described     

Identifying multipath within terrestrial video using a locallymodified GCR signal

The results of a new simple method of obtaining the multipath channel distortion for terrestrial transmitted video is presented. It finds in isolation, the VSB induced detected quadrature ghost relative amplitudes which had previously been difficult. The method is based on correlation of the received signal with a version of the PAL GCR standard signal which has been modified by the inherent quadrature forming filter spectrum of the receiver VSB filter