Cable television

• 1. Introduction

  ›

  Cable television begins, in a sense, on a mountaintop. In 1948, communities in the United States and Switzerland found themselves cut off from the television signals that urban viewers were already enjoying. The problem was simple physics: hills blocked radio waves. The solution was equally direct. Entrepreneurs erected tall community antennas at high elevations and ran cable directly into homes. They called it community antenna television, and the abbreviation CATV stuck for decades.

  What started as a workaround for geography quietly grew into one of the most pervasive media systems ever built. By 1988, cable had passed through the front doors of 52.8 percent of all American households. That number had been a mere 6.4 percent in 1968. The questions worth asking are not just how that growth happened, but what it changed about the way people watch, pay for, and think about television.

• 2. Wires Through the Hills

  ›

  Alfred, New York offers an unusual footnote in early cable history. This college town was one of the rare American communities that used its cable system to retransmit Canadian channels rather than only American ones. The inversion captures something essential about cable's origins: it was never about glamour. It was about closing the gap between what a transmitter could reach and what a subscriber actually wanted to see.

  The earliest American cable systems were commercial operations that took root in the 1950s. They did nothing more sophisticated than receive weak broadcast signals, amplify them, and pass them along unshielded wires to nearby homes. The receiving antenna was simply taller than anything an individual household could afford to install. In hilly or mountainous terrain, that antenna went up to a high elevation where the signal was strong.

  Canada presented a different dynamic. Communities there already had their own local signals, yet viewers still subscribed to cable because they wanted to receive American programming. That appetite for more, for signals that couldn't be reached by geography or regulation alone, became the commercial engine the industry ran on.

• 3. The Channel Ceiling

  ›

  Early television receivers could tune twelve channels, numbered 2 through 13. But the maximum number of channels that could practically broadcast within a single city was seven. Receivers at the time could not handle strong local signals on adjacent channels without producing distortion. Engineers had to leave frequency gaps between channels 4 and 5 and between 6 and 7 to make even that much work.

  As equipment improved, all twelve VHF channels became usable, but only up to a point. Amplifiers of the era struggled to carry frequencies above 250 MHz to distant parts of a coaxial network. UHF channels could not be used at all. To push beyond twelve channels, operators turned to non-standard midband frequencies, slotted between the FM band and channel 7, or to superband channels beyond channel 13 up to about 300 MHz. Subscribers needed separate tuner boxes just to access these signals, which arrived retranslated onto channel 2, 3, or 4.

  The passage of the All-Channel Receiver Act in 1964 required all new television sets to include a UHF tuner. It took a few more years after that before UHF stations became genuinely competitive. Meanwhile, those midband frequencies became home to early pay television experiments, among them The Z Channel in Los Angeles and HBO, both transmitted in the clear because standard television sets of the period could not receive them and ordinary viewers had no way to detune their sets to pick them up.

• 4. Scrambling and the Set-Top Box

  ›

  Electronics hobby magazines including Popular Science and Popular Electronics created an unexpected obstacle for the cable industry. The descrambling circuitry that operators used to protect premium channels was published openly in those publications. Anyone with more than a basic knowledge of broadcast electronics could build their own descrambler and receive programming without paying for it.

  As consumer television sets gradually gained the ability to receive all 181 FCC-allocated channels, premium broadcasters had no remaining option but to scramble their signals. The scrambling circuitry appeared in commercial television tuners and VCRs for a time during the 1980s and 1990s, which cost cable operators significant revenue. The industry eventually returned to the set-top box model it had used since the 1970s. Each box is activated by a code that the cable company sends only after a subscriber signs up. If a subscriber stops paying, the company can send a signal to deactivate the box remotely.

  Set-top boxes grew more capable over time. Providers began offering high-definition wireless digital video recorder receivers connected through HDMI or component outputs. Basic boxes continued to deliver standard-definition pictures over the old coaxial connection. The boxes became the point of control for a subscriber's entire service relationship, from channel access to billing to the ability to request pay-per-view programming.

• 5. Fiber, Coax, and the Modern Network

  ›

  A single modern cable network and headend can serve an entire metropolitan area. Most systems now use a hybrid fiber-coaxial architecture, abbreviated HFC. The trunklines running from the headend out to local neighborhoods carry optical fiber, which delivers far greater bandwidth than coaxial cable and leaves room for future expansion.

  At the headend, the original electrical signal is converted into an optical signal and fed into the fiber. That fiber runs to distribution hubs, from which multiple fiber strands fan out to optical nodes placed throughout local communities. At each optical node, the signal converts back to an electrical form and travels the remaining distance to homes over coaxial cable lines on utility poles. Along the way, signal amplifiers and line extenders maintain strength, passing the signal to customers through passive RF devices called taps.

  The downstream channels, carrying programming to subscribers, occupy a band of frequencies from approximately 50 MHz to 1 GHz. Upstream channels, which carry data from a customer's box back to the headend for features such as pay-per-view requests and internet access, occupy a narrower band from 5 to 42 MHz. One enduring problem in older systems is that amplifiers placed along cable routes were designed to carry signals in only one direction. Enabling broadband upload speeds required expensive upgrades to replace those unidirectional devices.

• 6. Beyond Television

  ›

  Coaxial cable carries far more signal capacity than television programming actually uses. That surplus bandwidth opened a second commercial chapter for cable operators. Broadband internet access arrived through cable modems, which convert network data into a digital signal that travels over the same coaxial lines that carry programming. The standard for this is called DOCSIS.

  Cable telephone service followed in North America, Australia, and Europe. The system installs a telephone interface at the customer's premises that converts analog signals from the home's existing phone wiring into a digital signal. That signal then replaces the analog last mile, connecting into the public switched telephone network at the company's switching center. One standard for digital cable telephony, PacketCable, drew particular attention for its ability to meet the quality-of-service demands that emergency calls require.

  The combination of television, telephone, and internet access packaged together became known as triple play, a term used whether the provider was a cable company or a traditional telecommunications carrier. Traditional cable providers and telecom companies increasingly competed for the same household on all three fronts. In Africa, however, cable television gained little traction. The economics did not work: laying cable across sparsely populated areas was not cost-effective, and microwave-based systems became the alternative approach.

• 7. Narrowcasting and Local Voices

  ›

  During the 1980s, United States regulations modeled on public, educational, and government access requirements helped spark a new kind of television. Cable-only stations appeared across major markets with their own news bureaus. These outlets could provide coverage that was more immediate and more geographically specific than anything the nearest network newscast offered.

  These local cable stations did not broadcast over the air and were not regulated by the FCC. Their call signs carried no technical meaning. Some adopted on-air branding similar to nearby broadcast affiliates. Many eventually evolved into what are now digital subchannels, where a main broadcast station rebroadcasts a nearby affiliate's programming and fills the remainder with its own local news and community content.

  By the late 1980s, cable-only signals outnumbered broadcast signals on cable systems, some of which had expanded beyond 35 channels. Specialty channels focused first on movies and major sporting or performance events, then diversified into narrowcasting: programming aimed at specific audiences rather than the broadest possible one. By the 1990s, customers could subscribe to different service tiers to access specialty channels, movie channels, and foreign-language channels above the basic selection. Cornwall, Ontario represents one early experiment in a different direction: its cable operator ran a dual distribution network with channels 2 through 13 carried separately on each of two cables.