Technical Background:
Cable Television and Advanced Services

March 4, 2004

Prepared by
Columbia Telecommunications Corporation
5550 Sterrett Place, Suite 200
Columbia, MD 21044
410.964.5700
www.internetCTC.com

Cable has become the dominant form of broadband communications to residences. Owing to its physical capacity, it can carry a wider range of communications services than a copper telephone wire or power line.

As the largest communications “pipe” entering a residence or small business, it has the theoretical capability of simultaneously transporting:

• Hundreds of video channels
• Two-way data-- hundreds of times faster than telephone wires
• Advanced voice services
• Future interactive services

Cable has evolved since its inception in the 1950s and 1960s and continues to evolve. The original systems served tens of thousands of homes and provided improved reception of regular off-air television. Later systems also offered satellite channels (HBO, TBS, pay-per-view, CSPAN).

“Bandwidth” refers to the speed or capacity of the cable. Older systems carried 40 to 60 TV channels (330 to 450 MHz of bandwidth). Upgraded systems have 750 to 860 MHz of bandwidth, now including about 30 MHz from the subscriber to the system. The new bandwidth enables the system to have more channels and more advanced services.

“Analog” refers to traditional television or voice technology. If an analog signal becomes weak, it may appear snowy or distorted.

“Digital” refers to the transmission or storage of video, data, or voice signals as “1”s or “0” and is a more advanced technology than analog. Conversion from analog to digital is done at the studio or headend. It results in:

• generally better picture quality
• ability to compress more channels in a given amount of bandwidth
• availability of high definition television (HDTV)
• ability to store video on a computer hard drive or digital tape
• ability to view video on a computer
• ability to edit video on a computer

The use of digital technology and the increasing power of computer desktops and the Internet may result in Internet technologies replacing television broadcast stations, cable-TV, and direct satellite technologies.

“Fiber Optics” are strands of glass used in new-technology communications cables. Cable companies use fiber optics between their main buildings in failsafe rings. Cable companies generally also construct fiber from their main buildings to neighborhoods.

Fiber optics offer:

• Improved signal capacity
• Ability to provide two-way services to each customer in a large system
• Ability to “narrowcast” to each neighborhood (and thus re-use the same channels neighborhood-by-neighborhood)
• Ability to provide capacity for Internet, video-on-demand, and voice

Fiber cables are generally lashed to the pre-existing cable-TV cables. Cable systems typically use a hybrid fiber-coax (HFC) design. In HFC, the fiber cable interfaces with the coaxial cable in each neighborhood at a “node.”

Another design type is fiber-to-the-premises (FTTP). FTTP extends the benefits of narrowcasting to individual homes or businesses, providing practically unlimited capacity. Few cable companies use FTTP. Most FTTP is offered by municipal providers, networks installed by builders and developers, and trials by telephone carriers.

Coaxial cable (traditional metallic cable) remains in most neighborhoods and premises. Limitations relative to fiber optics include capacity, signal quality, and reliability.

Per foot, the costs of fiber or coaxial construction are comparable. Most costs are due to labor—therefore in areas of new construction it is optimal to build fiber instead of or in addition to coaxial cable.

Cable is built and maintained in the public rights of way. Cable construction and maintenance pose public safety issues and create burden and expense on the public rights of way.

Video-on-demand (VOD) provides the ability to select between thousands of video programs with rewind, pause, and fast-forward functionality. Cable provides VOD by dedicating a channel between the viewer and the system.

VOD is stored on disk drives and streamed to the viewer from a video file server.

Voice-over-IP (VoIP) delivers voice services using the same channels and technical platform as the cable modem system.

Depending on the configuration of the system, cable VoIP:

• May be a toll-grade service or suitable as a backup, low-cost second line
• May or may not operate if the power at the premises has failed
• May or may not provide identification or location information to a 911 dispatcher

Some cable operators use their systems as backbone networks for wireless services and connecting their systems to wireless antennas to provide:

• Wireless hotspot service
• Extend service to hard-to-reach areas:
  • Office parks
  • Malls, shopping centers
  • Public areas
    • Multi-dwelling units