sion can be lossy. On the other hand, if texts or data files are required to be compressed, a lossless compression must be used (see Chapter 3). Compression/decompression of a video signal became possible thanks to the introduc- tion of digital television, which acted as an improvement over analogue television. Digital television now offers High-Definition Television (HDTV) as well as standard-definition TV, an increased number of programs, reception in moving means of transportation, and distri- bution over the Internet and telecommunications networks. New video codec applications have evolved rapidly. For example, MPEG-1 was devel- oped for video storage on CD-ROM, and MPEG-2 was developed for video broadcast. H.263 was intended for videoconferencing. The trend in video codecs is expected to lead to a reduction in data speeds due to compression. For example, a reduction of approximately 3 Mb/s is expected for good-quality standard-definition video under MPEG-2. The transmis- sion of video through Internet Protocol data is going to be an important visual service in the future, demanding more bandwidth because of the increased number of users. In this case, it is expected that several Mbit/s of IPTV data traffic will be on demand in the future as well. Finally, mobile video will be a service with increasing demand in the future. Com- pressions between 128 kbit/s and 64 kbit/s are expected. Acknowledgment The authors would like to acknowledge the contribution of Professor J. E. Flood in describing modulation. Resources Carlson, B., Crilly, B., and Rutledge, J. (2002) Communication Systems, Fourth Edition, McGraw-Hill, 850. Couch, L. (2001) Digital and Analogue Communications Systems, Seventh Edition, Prentice Hall, 756. Dunlop, J., and Smith, D. G. (1994) Telecommunication Engineering, Third Edition, Chapman and Hall, Chapter 2 Data Transmission Forouzan, B. (2006) Data Communications and Networking, Fourth Edition, McGraw-Hill, 1134. Glover, I., and Grant, P. M. (2004) Digital Communications, Second Edition, Pear