Other

Fauci to step down after decades as top US infection expert

Dr. Anthony Fauci, the nation's top infectious disease expert who became a household name—and the subject of partisan attacks—during the COVID-19 pandemic, announced Monday he will leave the federal government in December ...

Neuroscience

Finding structure in the brain's static

While sleeping, the entire brain rolls through long, slow waves of electrical activity, like waves on a calm ocean. Researchers call that state of consciousness "slow wave sleep." Waking up changes the pattern of electrical ...

Vaccination

South Africa launches drive to vaccinate 500,000 in 2 days

South Africa launched a new COVID-19 vaccination drive Friday and will try to give doses to 500,000 people in two days to reinvigorate a flagging campaign that's coming up against hesitancy and complacency in the continent's ...

Vaccination

In world first, Cuba starts COVID jabs for toddlers

Cuba on Monday became the first country in the world to vaccinate children from the age of two against COVID-19, using home-grown jabs not recognized by the World Health Organization.

page 1 from 21

Television

Television (TV) is a widely used telecommunication medium for transmitting and receiving moving images, either monochromatic ("black and white") or color, usually accompanied by sound. "Television" may also refer specifically to a television set, television programming or television transmission. The word is derived from mixed Latin and Greek roots, meaning "far sight": Greek tele (τῆλε), far, and Latin visio, sight (from video, vis- to see, or to view in the first person).

Commercially available since the late 1930s, the television set has become a common communications receiver in homes, businesses and institutions, particularly as a source of entertainment and news. Since the 1970s the availability of video cassettes, laserdiscs, DVDs and now Blu-ray discs, have resulted in the television set frequently being used for viewing recorded as well as broadcast material.

Although other forms such as closed-circuit television are in use, the most common usage of the medium is for broadcast television, which was modeled on the existing radio broadcasting systems developed in the 1920s, and uses high-powered radio-frequency transmitters to broadcast the television signal to individual TV receivers.

Broadcast TV is typically disseminated via radio transmissions on designated channels in the 54-890 megahertz frequency band. Signals are now often transmitted with stereo and/or surround sound in many countries. Until the 2000s broadcast TV programs were generally recorded and transmitted as an analog signal, but in recent years public and commercial broadcasters have been progressively introducing digital television broadcasting technology.

A standard television set comprises multiple internal electronic circuits, including those for receiving and decoding broadcast signals. A visual display device which lacks a tuner is properly called a monitor, rather than a television. A television system may use different technical standards such as digital television (DTV) and high-definition television (HDTV). Television systems are also used for surveillance, industrial process control, and guiding of weapons, in places where direct observation is difficult or dangerous.

Amateur television (HAM TV or ATV) is also used for experimentation, pleasure and public service events by amateur radio operators. HAM TV stations were on the air in many cities before commercial TV stations came on the air.

This text uses material from Wikipedia, licensed under CC BY-SA