基于FPGA的MPEG-2传输流复用卡的设计与实现

MPEG-2传输流复用卡是数字电视前端的关键设备.介绍一种基于FPGA的PCI接口传输流复用卡,详细介绍其工作原理、设计思想、硬件结构及实现方法,并给出该卡在Linux下的驱动程序框架结构.     

AVS标准系统层介绍及复用的实现

在介绍AVS标准的系统部分的基础上,阐述了与MPEG-2标准系统部分的联系与区别.给出了一种易于实现的以帧为单位打PES分组包的复用方法,实现了完全符合AVS标准的传输流和节目流的复用.并且,利用AVS系统部分与MPEG-2系统部分的高度兼容性,给出了一种成本极其低廉的实现AVS音视频数据流复用解复用的方法.该方法完全不需要研制AVS复用解复用设备,而是利用现有的MPEG-2复用解复用设备就实现了AVS标准的传输流和节目流的复用.     

MPEG-2传输中复用及解复用器的一种设计方案

在介绍MPEG-2传输流的格式及传输过程中的复用和解复用问题的基础上,提出了一种MPEG-2传输信号流的复用及解复用的设计方案.复用时,插标记位,不删空包,简化了复用器设计,节约了复用器资源;解复用时,再删空包并提取PCR计算码率,恢复原始码流.最后给出了利用FPGA实现该方案的具体方法和工作流程,该复用、解复用方案简洁清楚,十分利于实际工程实现.     

MPEG-2传输流的复用

MPEG-2是数字电视系统中的关键技术之一,介绍了MPEG-2的概念、系统标准及MPEG-2传输流（TS）的结构,着重介绍了MPEG-2传输流（TS）的复用技术及复用方式。     

CATV的统计复用模型以及软件复用的具体实现

提出了一种基于CATV的统计复用模型,同以往的模型相比,这里通过设定自相关函数和相邻队列长度来确定分组和缓冲之间的关系,从而为复用器的设计奠定基础.同时利用这个模型的理论基础,在CATV网络上具体设计了一个基于软件复用的MPEG-2传输流复用器,在实际的网络上的测试结果基本能够满足8～16路信号的连续复用.     

MPEG-2传输流解复用在内嵌ARM核的FPGA上的实现

本文介绍了MPEG-2传输流解复用的原理,使用内嵌ARM的FPGA芯片EPXA10实现了MPEG-2传输流的解复用,并从硬件设计和软件结构两个方面详细地介绍了设计思想。     

模块化并行结构数字有线电视传输流再复用器设计

介绍了一种在有线电视前端系统中的MPEG-2传输流再复用器的设计方案。该方案采用模块化并行多处理器结构，实现较为复杂的MPEG-2传输流解复用、再复用的过程。还分析了MPEC-2系统级节目特殊信息的内容及结构。     

MPEG-2传输流的码流分析

本文介绍MPEG-2传输流的语法结构及复用，以及ETR290标准规定的传输码流3级错误检测参数，同时结合码流分析软件对MPEG-2传输流的语法结构作-离线分析。     

MPEG-2传输流多路复用的软件实现方法

提出了一种MPEG-2单节目传输流多路复用的软件实现方案。该方法在不改变原有单路传输流(TS)的节目参考时钟(PCR)的情况下,通过修改参加复用的传输流的节目特殊信息(PSI)以及将公共包识别符(PID)进行重新映射,并利用传输速率和PCR之间的关系,仅采用控制空包插入个数以及各传输流中TS包插入位置的方法,将参加复用的各路单节目传输流复用为一路多节目传输流。     

MPEG-2传输流复用去复用机制分析

在对数字电视的软硬件结构作简要分析的基础上,对其控制程序的关键技术——MPEG-2传输流复用去复用机制进行了剖析。     

Digital television on ATM networks: optimum chain for coding andtransmission

This paper presents a global optimization of the transmission chain for video on asynchronous transfer mode (ATM) channels. This optimum control includes compression, transmission, and decoding. First, the gain in statistical multiplexing is put forward to demonstrate that transmitting at variable rates on asynchronous multiplexing links is more efficient than exploiting the constant rate on synchronous links. The joint optimization relies on both the entropy rate and the end-to-end image quality. This requires the characterization of the video sources as entropy generators, and the development of the entropy rate-distortion functions in the coder and the transmission channel. Quantizers and variable-length entropy coders in coding, traffic, and queues in transmission multiplexing each lead to performance functions expressing quality in terms of entropy rate. The objective measures of quality are, respectively, the PSNR in terms of the output data rate and the cell loss in terms of the network loads. The main advantage of transmitting on variable bit-rate channels is to permit the generation of image sequences at constant subjective quality on the coding side, and the saving of transmission bandwidth through a gain in statistical multiplexing on the network side. Mirrored control actions are described for coding and multiplexing; they lead to a unique global optimum of the transmission chain. Since the decoders are generally slaved to the coding and transmission performances, they are restricted to perform independent optimum signal reconstruction     

Statistical multiplexing gain for variable bit rate video codecs in ATM networks

Asynchronous transfer mode (ATM) broadband networks will support variable bit rate video codecs, which are capable of maintaining a constant picture quality. To demonstrate this capability, a prototype hardware video coder has been developed in the Siemens Central Communications Laboratories. The prototype uses interframe coding, combined with a discrete cosine transform, and is able to reproduce the original picture quality, independent of signal sources or picture material used. A gain in transmission efficiency is expected when several video sources share a common ATM channel (‘statistical multiplexing’). This paper reports on a series of measurements that have been performed using this coder for a large variety of video sources to determine the possible gain in transmission efficiency. The main results are: for realistic video phone scenes, up to about three times the number of signals can be transmitted compared to transmision with constant rate and the same picture quality, if the output signal of the coder has been smoothed over a period of one frame. Smoothing over shorter periods reduces the potential gain substantially. The statistical multiplexing gain increases with the duration of the picture sequences due to the criterion of constant picture quality. It varies very little with the acceptable packet loss rate.     

统计复用发展综述

本文首先综述了统计复用的相关术语和概念;其次综述了可变比特率统计复用与固定比特率比较、开环和闭环统计复用的比较,以及MPEG-2和H.264/AVC统计复用的比较。     

阵列波导光栅复用器的数学特性

叙述了基于阵列波导光栅复用器的结构与原理,在此基础上分析了其输入与输出信号的傅里叶变换、信号传输、信号循环移位,复用、解复用和波长路由的信号矩阵变换等光信号时空变换和光信号处理的数学特性,拓宽了阵列波导光栅波分复用器的应用领域。     

基于超连续谱和超结构光纤光栅的波分复用/光码分复用系统

实验验证了基于超连续谱(SC)和超结构光纤光栅(SSFBG)的波分复用/光码分复用(WDM/OCDM)混合系统,超结构光纤光栅实现了对超连续谱光源的双波段同时相位编解码。由于波分复用/光码分复用系统中信道间干涉和噪声的影响,解码输出脉冲的信号波形出现劣化,自相关曲线旁瓣明显增大,自相关峰展宽至8.2 ps。在非线性放大环镜(NALM)的阈值判决作用下,解码输出脉冲的信号波形质量有了明显的改善,自相关峰宽度压缩至4.8 ps,较好地抑制了自相关曲线的旁瓣和噪声。实验中非线性放大环镜的输入信号峰值功率约为8 mW。     

Computationally efficient variational Bayesian method for PAPR reduction in multiuser MIMO‐OFDM systems

This paper investigates the use of the inverse‐free sparse Bayesian learning (SBL) approach for peak‐to‐average power ratio (PAPR) reduction in orthogonal frequency‐division multiplexing (OFDM)‐based multiuser massive multiple‐input multiple‐output (MIMO) systems. The Bayesian inference method employs a truncated Gaussian mixture prior for the sought‐after low‐PAPR signal. To learn the prior signal, associated hyperparameters and underlying statistical parameters, we use the variational expectation‐maximization (EM) iterative algorithm. The matrix inversion involved in the expectation step (E‐step) is averted by invoking a relaxed evidence lower bound (relaxed‐ELBO). The resulting inverse‐free SBL algorithm has a much lower complexity than the standard SBL algorithm. Numerical experiments confirm the substantial improvement over existing methods in terms of PAPR reduction for different MIMO configurations.     

GA-based optimal dimensioning of three-level traffic shaper for statistical multiplexing in ATM networks

In this paper we discuss genetic algorithm (GA)- based optimal dimensioning of the three-level traffic shaper (tlts) for statistical multiplexing in atm networks. As the objective function for the optimal dimensioning, we consider three alternatives — the variance of the output cell service periods, the variance of the output cell rates, and the sum of squared differences of adjacent cell service periods. We perform simulations for optimal dimensioning of the tlts for statistical multiplexing of vbr video services, and we confirm that the objective function based on the variance of the output cell rates is the most suitable among the three alternatives. The framework of the optimal dimensioning procedure introduced in this paper can be easily extended to other optimal design problems in atm networks for which traditional gradient- based optimal dimensioning methods or random search techniques are not easily applicable due to the nonlinearities and complexities of the related functions and the discreteness of the involved parameters.     

Diode Circuits for Pulse Regeneration and Multiplexing at Ultrahigh Bit Rates

Clocked step-recovery diode (SRD) circuits are investigated for regenerating and multiplexing PCM-type signals in the range from 0.1 to a few gigabits per second. One regenerator type is particularly suited for operating with signals in the 1-V range, whereas a differential version employing a magic T was developed for handling signals of down to about 5 mV. By making use of line transformers as coupling networks, high-level versions have been cascaded. Experiments performed at 0.3 and 1 Gbit/s yielded voltage amplifications (peak amplitudes) of 2.5-5.5 for single stages, and insertion power gains of 7-11 dB for 2-3 stage cascades. Diode stages have also been used for multiplexing 4 and 2 individual bit streams to give a combined output signal at 1 and 2 Gbit/s, respectively. In a preliminary multiplexer experiment an output at 4.5 Gbit/s was obtained. Finally, possibilities are discussed for improving the performance of the regenerators/multiplexers and for their applications.     

CMOS circuit for readout of microbolometer arrays

A CMOS circuit for the readout of microbolometer arrays is presented. It provides a pulsed bias for the microbolometers, signal amplification and multiplexing to a common output. The chip can be used with linear and small two-dimensional arrays of microbolometers realising a hybrid infrared sensor     

IPQAM前端插入VOD点播业务的传输方案

分析IPQAM前端插入VOD点播业务的传输方案,介绍在前端采用频率空间复用的网络结构实现IPQAM数字电视信号的定向插播,以及IPQAM输出端口并发流的组合分配设计。