The CATV industry steadily improved it s delivery technology from 1941 to date. The industry focused on the downstream delivery of services including videotext, telext, other forms of electronic publishing, and information-age services, home security, and digital audio programming in addition to the video channels. The cable companies, in the late 1980s and early 1990s, realized that unused bandwidth within the cable TV spectrum could be used as part of the Information Superhighway . Many cable companies began upgrading infrastructure during this time period to fiber optics for much of the services to meet reliable data transmission. Video has true broad bandwidth within its medium.
Video is a real bandwidth hog.
The video spectrum uses 4.2 MHz of bandwidth. The video pipe reaches from 6 MHz to 750 MHz, with TV using the bandwidth from 55 MHz to 550 MHz. Cable has two way access within this spectrum. This connection capacity is readily available to large numbers of subscribers via the installed cable TV media. All cable signals start as digital data at the cable company Central Office and are transmitted to universal broadband routers where the digital data is converted into RF signals.