Overview
This lecture covers the evolution of television broadcasting technology from wireless to cable, the emergence of cable internet, and key differences between cable and other broadband technologies.
History of Television Broadcasting
- Early television broadcasts were wireless, sent from large towers to home antennas.
- Viewers needed to be within broadcast range to receive television signals.
- Cable television began in the late 1940s to serve remote areas out of wireless range.
- Cable TV grew slowly until the Cable Communications Policy Act of 1984 deregulated the industry.
- Following deregulation, cable television rapidly expanded in the U.S. and globally.
Cable Television and Internet
- By the early 1990s, U.S. cable infrastructure equaled the size of the public telephone network.
- Cable companies explored providing internet using existing coaxial TV cables.
- Coaxial cables could transmit more data than required for TV, enabling high-speed internet.
- Cable broadband delivers internet using frequencies that do not interfere with TV broadcasts.
Shared Bandwidth and Technology Comparison
- Cable internet uses a shared bandwidth model, where multiple users share the same network segment.
- DSL and dial-up provide a dedicated line from each user to a central office (CO), allowing guaranteed bandwidth.
- COs were originally staffed switchboards, now replaced by automated hardware.
- Shared bandwidth can cause slowdowns during peak usage times in cable networks.
- Cable companies have upgraded networks to reduce the impact of shared bandwidth, but slowdowns still occur.
Cable Internet Infrastructure
- A cable modem connects the consumer's network to the cable provider.
- The cable modem termination system (CMTS) aggregates multiple cable connections to the ISP's core network.
Key Terms & Definitions
- Coaxial cable — a type of cable used to transmit television and internet data.
- Cable broadband — high-speed internet delivered through cable TV infrastructure.
- Shared bandwidth — multiple users share a fixed amount of data transfer capacity.
- Central office (CO) — a local facility connecting users directly to the telephone network.
- Cable modem — device connecting a user's network to the cable provider.
- CMTS (Cable Modem Termination System) — equipment at the provider's end managing multiple cable connections.
Action Items / Next Steps
- Review key differences between cable and DSL broadband infrastructure.
- Understand the concept of shared bandwidth and its impact on internet speeds.