新型编译码器的应用

编码器 MC145026和译码器 MC145027、MC145028是美国莫托罗拉公司80年代中期产品,它们在实现多路遥控中具有电路简单、抗干扰性能强、工作稳定可靠、系统及功能容易组合和扩展等优点,广泛应用于工业控制、家用电器及其它电子产品。本文以四通道遥控电源开关为例,介绍新型编、译码电路的应用。     

CMOS PCM编译码器CSC3057的内电路剖析及编码原理

本文根据ＰＣＭ编译码器ＣＳＣ３０５７的内电路结构，介绍了该电路的功能特点及信号流程。为使用户在应用时了解内电路的工作过程，文章较详细地介绍了电路的编码过程。     

实现和优化Turbo编译码器

介绍了Turbo编译码器的实现及优化过程.     

四相相移键控（QPSK）差分编译码器的实现

为了消除四相相移键控（ＱＰＳＫ）调制方式中相干解调时载波恢复存在的相位模糊问题，本文推导了在收发两端所分别插入的自然码差分编译码方程。在此基础上，阐述了采用中规模集成电路（数据选择器）实现自然码差分编码器和译码器的具体步骤、硬件实现电路。最后就文中所实现的编码器和译码器硬件电路进行了扼要的讨论。     

PCM编译码器CSC3057中单元电路的熔断微调测试原理

本文根据PCM编译码器CSC3057的内电路结构,简介了该电路的功能特点,并在此基础上论述了有关单元电路的熔断微调原理。文章对于制定此类电路的熔断测试方案,具有一定的指导意义。     

一种简单分组码编、译码器的单片机实现方案

本论文给出了一种简单分组码-（7,4）汉明码编、译码器的单片机实现方案。在硬件实现上验证了（7,4）汉明码的纠一位随机错误能力和交织度为2时的纠两位突发错误的能力。     

Subjective assessment method for television digital codecs

Results of previous experiments to compare the performance of quality and impairment types of subjective grading scales for television pictures have been re-examined with particular reference to performance near the threshold of visibility. No evidence was found to suggest that the quality scale should be superseded for assessing television digital codecs.     

Double-stimulus quality rating method for television digital codecs

Results are presented showing the development of a subjective method for the assessment of television digital codecs which preserves many of the features of the existing single-stimulus method employed for television transmission impairments. Rating standards are found to be highly stable in the presence of changes in the general level of impairment.     

广播电视音视频系统传输与应用

文章在阐述广播电视音视频传输系统结构组成的基础上,分析了SCM广播电视音视频系统传输技术及其具体的应用。SCM技术在广播电视音视频系统传输稳定性、可靠性等方面更具优势,值得大范围推广应用。     

浅析媒体资产管理系统在广电系统的应用

媒体资产管理系统在广电领域具有广泛应用。简要阐述了媒体资产管理的相关概念,介绍了广电媒体资产管理系统的组成、各子系统功能以及相关关系,并对媒体资产管理系统在广电系统中的应用现状和前景进行了分析。     

Characterization of video codecs as autoregressive moving averageprocesses and related queueing system performance

A method of characterizing video codec sources in asynchronous transfer mode (ATM) networks as an autoregressive moving average (ARMA) process is described. Measurements of long-term mean and the autocorrelation function of cell interarrival times allow the parameter estimation of the ARMA model. The video source is then described by ARMA model. Furthermore, it is shown that the multiplexed stream of video cells is also an ARMA process. Such a cell stream is then applied to a model of a queuing system to obtain performance measures of the system. Perturbation analysis is then performed on the functional behavior of the queuing system by appropriate perturbation of the model parameters to determine cell waiting time sensitivity due to slight variations of the input process     

Rate-distortion optimization of scalable video codecs

In this paper joint optimization of layers in the layered video coding is investigated. Through theoretical analysis and simulations, it is shown that, due to higher interactions between the layers in a SNR scalable codec, this type of layering technique benefits most from joint optimization of the layers. A method for joint optimization is then proposed, and its compression efficiency is contrasted against the separate optimization and an optimized single layer coder. It is shown that, in joint optimization of SNR scalable coders when the quantization step size of the enhancement layer is larger than half the step size of the base layer, an additional improvement is gained by not sending the enhancement zero valued quantized coefficients, provided they are quantized at the base-layer. This will result in a non-standard bitstream syntax and as an alternative for standard syntax, one may skip the inter coded enhancement macroblocks. Through extensive tests it is shown that while separate optimization of SNR coders is inferior to single layer coder by more than 2 dB, with joint optimization this gap is reduced to 0.3–0.5 dB. We have shown that through joint optimization quality of the base layer video is also improved over the separate optimization. It is also shown that spatial scalability like SNR scalability does benefit from joint optimization, though not being able to exploit the relation between the quantizer step sizes. The amount of improvement depends on the interpolation artifacts of upsampled base-layer and the residual quantization distortion of this layer. Hence, the degree of improvement depends on image contents as well as the bit rate budget. Simulation results show that joint optimization of spatial scalable coders is about 0.5–1 dB inferior to the single layer optimized coder, where its separate optimization counterpart like SNR scalability is more than 2 dB worse.     

电视会议系统的中频切换技术

１前言中国广播电视节目的远距离传送最初是使用模拟微波,然后发展到使用模拟卫星传送。目前随着数字微波、数字卫星和光纤技术的发展,不少省市的模拟微波设备改成了数字微波设备。但是,模拟微波具有投资少、见效快、建设周期短、技术成熟、性能稳定、抗自然灾害能力强和易于维护等特点,仍被广泛地用于地（市）至县及县至乡镇的有线电视微波联网。近期正规微波厂家生产的模拟微波设备,从质量指标到设备的稳定性、可靠性均比以前的产品有了很大的提高,所以,目前已建成的地（市）至县及县至乡镇的模拟微波网中,大部分的枢纽站、中继站…     

Application of NB/WB AMR speech codecs in the 30-kHz TDMA system

A new system enhancement method is proposed for the EIA/TIA-136 system offering both channel operational range extension and improved performance within the current operational range. The existing time-division multiple-access (TDMA) (136) speech codec, the IS-641 enhanced full rate vocoder, operates at a fixed bit rate and does not allow the reallocation of bits to channel error protection as channel conditions degrade. The research presented here investigates the application of the narrow-band adaptive multirate (NB-AMR) speech codec and the wide-band AMR (WB-AMR) codec, both originally designed for the 200 kHz GSM channel, in the TDMA (TIA/EIA-136) 30-kHz system. In particular, we investigate adaptively allocating bits between NB/WB speech coding and error control coding within the limited channel bandwidth. Four modes out of 17 have been carefully chosen for the new TDMA/AMR system. Switching between codec rates as channel conditions change produces range extension below a C/I of 15 dB while also improving performance in the existing operational range above 15 dB. We keep the time slot formats unchanged so that our method is completely compatible with existing 136 systems.     

简述数字化在广播电视技术中的应用

在经济的发展下,科学技术随之提高,数字化在广播电视技术的使用中愈发普及.数字化技术身为广播电视技术中的重要方面,成为无法取缔的主要内容,可以有效提升广播电视信息在传输方面的效率以及质量,令电视节目的播放频道数量不断增加,人们对广播电视的所需均可获得满足,广播电视技术通过数字化的帮助,可以更加稳定的发展.