In our monitoring system , we decide to use the standard of video coding for low bit rate communication - h . 263 , because it can get better tradeoff between bit rate and image quality . this paper will emphasis on h . 323 and h . 263 standard , especially h . 263 algorithm and its optimization methods 对于isdn 、 pstn 、以太网等低速率信道，我们选择低码率视频编码标准h . 263进行图像的编解码，这是一种码率和图像质量折衷的编解码标准。
In our monitoring system , we decide to use the standard of video coding for low bit rate communication ? h . 263 , because it can get better tradeoff between bit rate and image quality . in this thesis , firstly , we introduce the development history of monitoring system and its basic architecture 对于isdn 、 pstn 、以太网等低速率信道，我们选择低码率视频编码标准h . 263进行图像的编解码，这是一种码率和图像质量折中较好的编解码标准。
Simulation indicates : using band - pass sampling is right in digitalizing if signal ; it is necessary to use special chip to process if digital signal ; at the same time , it is feasible to process base - band low speed signal ( am , fm etc . ) by software 仿真表明：中频数字化技术，使用带通采样方案是恰当的；现阶段对中频采样信号使用专用芯片作降速率处理是必然选择；同时，对基带低速率信号(如am 、 fm 、 bpsk信号)作全数字化软件处理是切实可行的。
Digital speech has preponderance over analog speech in reliability , robustness and security during communication . however , digital speech needs more bandwidth than the analog signal . especially with the requirement for communication frequency increasing , it ' s necessary to code speech signal at low rates 但是，数字化后的信号所占的频带大幅增加，特别是在带宽需求日益增长的今天，这个问题尤为突出，因此语音的低速率编码(即压缩编码)成为迫切的要求。
The services of electric power communication network have already expanded from telephone scheduling and transmitting data in low speed to digital user ' s service with high speed and great capacity , such as computer internet , wide area network and video transmission , etc . its structure has already developed from simple star topology , which is used to serve schedular center , to today ' s multicenter network to assure that the network can serve the requirement of increasing transmission of electric power information 电力通信网的业务已从调度电话、低速率远动数据传送扩展到高速、数字化、大容量的用户业务，例如计算机互联网、广域网、视频传送等。电力通信网的结构也已从单一服务于调度中心的简单星形方式发展到今天多中心的网状网络，以保证能为日益增长的电力信息传输需求服务。
Currently the key technology of low bit rate video communication is video compression coding and video conduction . according to the limitation of video compression coding currently , a research is done in my paper on the design of low bit rate video system with high compression ratios 目前低速率视频通信的主要问题是视频压缩编码和视频图像处理，本文通过对低速率视频系统的研究，针对目前视频压缩编码的局限性，以小波变换为基础构造了一个高压缩比、高质量还原图像的低速率视频系统。
