Television

D

Scanning Systems

The main US TV system (referred to as NTSC, after the US government’s standards committee) produces 30 images of 525 lines per second, but as with all systems across the world, each image consists of two interlaced scanning dots, working on alternate lines. This interlaced system produces less flicker than the single scanning of an entire image. Thus 60 half-pictures per second are actually produced, complying with the 60 Hz powerline frequency that is standard in the United States.

In Europe, 50 Hz is the electrical standard, and the two main European systems (PAL and SECAM) produce 50 half-images per second, making 25 whole images. The human eye perceives this rate of single images as forming continuous motion. PAL, a German development, is widely used in Western Europe; SECAM is used in France, and in much of Eastern Europe. Both have 625 lines, though France experimented with an 819-line SECAM system for a while.

E

HDTV

Recent experiments in Japan, Europe, and the United States have aimed at developing high definition TV (HDTV) based on picture resolutions of 1,125 and even 1,250 lines. HDTV is capable of being shown on a much larger screen, without loss of quality, and in a greater ratio of width to height. For the foreseeable future, HDTV seems likely to remain an expensive option, but may eventually become more widely adopted.

IV

Development of the TV Industry

The development of TV in Britain and the United States represents two very different legacies of the way governments and corporations developed radio and TV broadcasting in the pre-World War II period.

A

TV in the United States

A

1

NBC, CBS, and ABC

In the United States, the dominant concerns were NBC and the Columbia Broadcasting System (CBS Inc.), set up in 1927. These companies built their TV empires on the radio programming networks they created during radio’s heyday in the 1930s, funding expansion through the sales of sets, and of advertising.

Networks produced programmes for a chain of local stations across the country, some of which they owned, but most of which were affiliated with them. NBC and CBS were joined by another two broadcasting networks, American Broadcasting Company (ABC) and DuMont, in the 1940s, and until the 1980s, the trio of NBC, CBS, and ABC dominated the American TV landscape. DuMont went bankrupt in the 1950s, but a fourth network, Fox, owned by Rupert Murdoch, emerged in the late 1980s.

A

2

Network Affiliation

The domination of US TV by the networks was reinforced by the FCC’s 1952 decision to allocate only three VHF (very high frequency) stations to most urban areas. The first three stations in an area inevitably affiliated with the networks in order to get the best-known national shows. New channels were forced on to UHF frequencies, which were of poor reception quality, and unobtainable on most sets. Thus the American TV system developed as an advertising-funded, commercial system, dominated by a small number of companies.

B

TV in Britain