C. Radio in the usa
Radio in the United States is a major mass medium. Unlike radio in most other countries, American radio has historically relied on commercial sponsorship rather than public funding.
The expansion and dominance of FM radio, which has better audio quality but a more limited broadcast range than AM (amplitude modulation), represented the major technical change in radio during the 1970s and 1980s. FM radio (aided by the development of smaller portable radios and "Walkman" headsets) dominates music programming, while AM has largely shifted to talk and news formats.
Talk radio became more popular during the 1980s as a result of improved satellite communications. While before the 1980s talk radio was primarily a local phenomenon, the development of national spoken-word programming contributed to the renewed popularity of AM radio. However, this popularity is fading as previously AM-only stations begin moving their operations to FM simulcasts.
Both FM and AM radio have become increasingly specialized. Music formats, for instance, comprise a variety of specializations, the top five in 1991 being "country and western," "adult contemporary", "Top 40", "religion" and "oldies". Radio has been shaped by demographics, although to a lesser degree than television; modern radio formats target groups of people by age, gender, urban or rural setting and race. As such, freeform stations with broad-spanning playlists have become uncommon on commercial radio.
In an era in which TV is the predominant medium, the reach of radio is still extensive. Ninety-nine percent of American households have at least one radio; the average is five per household. Every day radio reaches 80 percent of the U.S. population. Radio continues to prevail in automobiles and offices, where attention can be kept on the road (or the task at hand) while radio is an audio background. The popularity of car radios has led to drive time being the most listened-to dayparts on most radio stations (followed by midday).
D. Television in the usa
Television is one of the major mass media of the United States. Household ownership is 96.7% and the majority of households have more than one TV set. As a whole, the television networks of the United States are the largest and most syndicated in the world.
The United States has a decentralized, market-oriented television system. There is a national public broadcast service known as the Public Broadcasting Service (PBS). Local media markets have their own television stations, which may be affiliated with or owned and operated by a TV network.
In addition to the thousands of local TV stations in the USA, there are three major national TV networks:
CBS - Columbia Broadcasting System
NBC - National Broadcasting Company
ABC (American Broadcasting Company
These networks show their broadcasts at the same time throughout the nation during prime time. Being the largest commercial TV companies in the country, these three networks are also responsible for the majority of TV programs broadcast nationwide.
Typically, they begin with an early-morning local news show, followed by a network morning show, such as NBC's Today, which mixes news, weather, interviews and music. Network daytime schedules consist of talk shows and soap operas, with one network (CBS) still carrying game shows and a handful of other games airing in syndication; local news may air at midday.
Syndicated talk shows appear in the late afternoon, followed by local news again in the early evening. ABC, CBS and NBC offer network news, generally at 6:30 or 7:00 in the Eastern Time zone and 5:30 or 6:00 in other areas. Local newscasts or syndicated programs fill the "prime access" hour or half-hour, and lead into the networks' prime time schedules, which are the day's most-watched three hours of television.
Typically, family-oriented comedy programs led in the early part of prime time, although in recent years, reality television like Dancing with the Stars has largely replaced them. Later in the evening, dramas like CSI: Crime Scene Investigation, House M.D., and Grey's Anatomy air.
At the end of prime time, another local news program comes on, usually followed by late-night interview shows, such as Late Show with David Letterman or The Tonight Show. Rather than sign off for the early hours of the morning (as was standard practice until the early 1970s in larger markets and until the mid-1980s in smaller ones), TV stations now fill the time with syndicated programming, reruns of prime time television shows or the local late news o'clock news, or 30-minute advertisements, known as infomercials, and in the case of CBS and ABC, overnight network news programs.
Saturday mornings usually feature network programming aimed at children (including animated cartoons), while Sunday mornings include public-affairs programs. Both of these help fulfil stations' legal obligations, to provide educational children's programs and public-service programming respectively. Sports and infomercials can be found on weekend afternoons, followed again by the same type of prime-time shows aired during the week.
While pay television systems existed in the USA as early as the late 1940s, cable television did not become popular until the early 1970s. There was one major problem: the cost of digging the roads up and of installing cables in people's homes. Today, most American households receive cable TV, and cable networks collectively have greater viewership than broadcast networks.
The first domestic communications satellite, Westar 1, was launched in 1974, and now it is as wide spread in the USA as cable television.