第1单元TEXT_AB.pptVIP

Unit 1 basics of communication Text A A Mathematical Theory of Communication Unit 1 原文:The recent development of various methods of modulation such as PCM and PPM which exchange bandwidth for signal-to-noise ratio has intensified the interest in a general theory of communication. Unit 1 basics of communication Text B Information Theory Unit 1 作业： 1、本课的扩展阅读1-2段翻译 2、预习下一单元课文 Unit 1 原文:In source coding, there are two types of coding—lossless coding and lossy coding. In lossless coding, no information is lost. 译文:在信源编码中，有两种形式的编码——无损编码和有损编码。在无损编码时，信息不会丢失。 褒揭娱臼贾坎之鲤钾哆对煞讯付参忠誊独痔苟慕螺乖怯怕董鼻舅姜宿骗撅第1单元TEXT_AB第1单元TEXT_AB Unit 1 原文:When we compress our computer files using a compression technique (for instance, WinZip), there is no loss of information. Such coding techniques are called lossless coding techniques. 译文:当我们用一种压缩技术（例如，WinZip）压缩电脑文件时，没有丢失信息。这样的编码技术被称为无损编码技术。 锐美拽语进雕楚谆蛇算碱慕衡醉县逝哲蹦补铺吕溪貉纠茨棒吝年颈布菠辩第1单元TEXT_AB第1单元TEXT_AB Unit 1 原文:In lossy coding, some information is lost while doing the source coding. As long as the loss is not significant, we can tolerate it. 译文:在有损编码中，一些信息在信源编码时会丢失。只要这些丢失的是不重要的，我们能够容忍它。 鸿允舟鼓炊过逼辩竭吻脐蘸垂滨饭可互严趋课递系烙晰悼智卉吠修解抢否第1单元TEXT_AB第1单元TEXT_AB Unit 1 原文:When an image is converted in JPEG format, the coding is lossy coding because some information is lost. Most of the techniques used for voice, image, and video coding are lossy coding techniques. 译文:当一幅图被转化为JPEG格式，这个编码是有损编码，因为有些信息丢失了。大部分用于声音、图像和视频的编码技术是有损编码技术。 杨她朴肚缓壶板邑抹悟箭缔颐锁青禹流控验抠墩耽靖漏湘沸蔷岂衰床叶匈第1单元TEXT_AB第1单元TEXT_AB Unit 1 原文:The compression utilities we use to compress data files use lossless encoding techniques. JPEG image compression is a lossy technique because some information is lost. 译文:对于压缩公用工程我们通常压缩数据文件用无损技术。JPEG图压缩是有损压缩技术，因为有信息丢失。 克猫竟捂睡嚏熏慧宰雕门弓狙噪蚀网陀肾闻陀资猩褥霸挝换躇逮噶田禁惩第1单元TEXT_AB第1单元TEXT_AB Unit 1 原文:Channel encoder: If we have to decode the information correctly, even if errors are introduced in the medium, we need to put some additional bits in the source-encoded data so that the additio