In its early stages of development, LIVESTREAM television employed a combination of optical, mechanical and electronic technologies to capture, transmit and display a visual image. By the late 1920s, however, those employing only optical and electronic technologies were being explored. All modern television systems relied on the latter, although the knowledge gained from the work on electromechanical systems was crucial in the development of fully electronic television.
The first images transmitted electrically were sent by early mechanical fax machines, including the pantelegraph, developed in the late nineteenth century. The concept of electrically powered transmission of television images in motion was first sketched in 1878 as the telephonoscope, shortly after the invention of the telephone. At the time, it was imagined by early science fiction authors, that someday that light could be transmitted over copper wires, as sounds were.
The idea of using scanning to transmit images was put to actual practical use in 1881 in the pantelegraph, through the use of a pendulum-based scanning mechanism. From this period forward, scanning in one form or another has been used in nearly every image transmission technology to date, including television. This is the concept of "rasterization", the process of converting a visual image into a stream of electrical pulses.
In 1884, Paul Gottlieb Nipkow, a 23-year-old university student in Germany, patented the first electromechanical television system which employed a scanning disk, a spinning disk with a series of holes spiraling toward the center, for rasterization. The holes were spaced at equal angular intervals such that, in a single rotation, the disk would allow light to pass through each hole and onto a light-sensitive selenium sensor which produced the electrical pulses. As an image was focused on the rotating disk, each hole captured a horizontal "slice" of the whole image.
Nipkow's design would not be practical until advances in amplifier tube technology became available. Later designs would use a rotating mirror-drum scanner to capture the image and a cathode ray tube (CRT) as a display device, but moving images were still not possible, due to the poor sensitivity of the selenium sensors. In 1907, Russian scientist Boris Rosing became the first inventor to use a CRT in the receiver of an experimental television system. He used mirror-drum scanning to transmit simple geometric shapes to the CRT.
Using a Nipkow disk, Scottish inventor John Logie Baird succeeded in demonstrating the transmission of moving silhouette images in London in 1925, and of moving, monochromatic images in 1926. Baird's scanning disk produced an image of 30 lines resolution, just enough to discern a human face, from a double spiral of Photographic lenses. This demonstration by Baird is generally agreed to be the world's first true demonstration of television, albeit a mechanical form of television no longer in use. Remarkably, in 1927, Baird also invented the world's first video recording system, "Phonovision": by modulating the output signal of his TV camera down to the audio range, he was able to capture the signal on a 10-inch wax audio disc using conventional audio recording technology. A handful of Baird's 'Phonovision' recordings survive and these were finally decoded and rendered into viewable images in the 1990s using modern digital signal-processing technology.
In 1926, Hungarian engineer Kálmán Tihanyi designed a television system utilizing fully electronic scanning and display elements, and employing the principle of "charge storage" within the scanning (or "camera") tube.
On 25 December 1926, Kenjiro Takayanagi demonstrated a television system with a 40-line resolution that employed a CRT display at Hamamatsu Industrial High School in Japan. This was the first working example of a fully electronic television receiver. Takayanagi did not apply for a patent. By 1927, Russian inventor Léon Theremin developed a mirror-drum-based television system which used interlacing to achieve an image resolution of 100 lines.
In 1927, Philo Farnsworth made the world's first working television system with electronic scanning of both the pickup and display devices, which he first demonstrated to the press on 1 September 1928.
WRGB claims to be the world's oldest television station, tracing its roots to an experimental station founded on 13 January 1928, broadcasting from the General Electric factory in Schenectady, NY, under the call letters W2XB. It was popularly known as "WGY Television" after its sister radio station. Later in 1928, General Electric started a second facility, this one in New York City, which had the call letters W2XBS, and which today is known as WNBC. The two stations were experimental in nature and had no regular programming, as receivers were operated by engineers within the company. The image of a Felix the Cat doll, rotating on a turntable, was broadcast for 2 hours every day for several years, as new technology was being tested by the engineers.At the Berlin Radio Show in August 1931, Manfred von Ardenne gave the world's first public demonstration of a television system using a cathode ray tube for both transmission and reception. The world's first electronically scanned television service then started in Berlin in 1935. In August 1936, the Olympic Games in Berlin were carried by cable to television stations in Berlin and Leipzig where the public could view the games live. In 1935, the German firm of Fernseh A.G. and the United States firm Farnsworth Television owned by Philo Farnsworth signed an agreement to exchange their television patents and technology to speed development of television transmitters and stations in their respective countries.On 2 November 1936, the BBC began transmitting the world's first public regular high-definition service from the Victorian Alexandra Palace in north London. It therefore claims to be the birthplace of television broadcasting as we know it today. In 1936, Kálmán Tihanyi described the principle of plasma display, the first flat panel display system. Mexican inventor Guillermo González Camarena also played an important role in early television. His experiments with television (known as telectroescopía at first) began in 1931 and led to a patent for the "trichromatic field sequential system" color television in 1940. Although television became more familiar in the United States with the general public at the 1939 World's Fair, the outbreak of World War II prevented it from being manufactured on a large scale until after the end of the war. True regular commercial television network programming did not begin in the U.S. until 1948. During that year, legendary conductor Arturo Toscanini made his first of ten TV appearances conducting the NBC Symphony Orchestra, and Texaco Star Theater, starring comedian Milton Berle, became television's first gigantic hit show. Since the 1950s, television has been the main medium for molding public opinion.
Amateur television (ham TV or ATV) was developed for non-commercial 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. In 2012, it was reported that television revenue was growing faster than film for major media companies. LIVESTREAM ONLINE TV.
The Weather Channel (TWC) is a US cable and satellite television network that, since May 2, 1982, broadcasts weather forecasts and weather-related news, along with entertainment programming related to weather 24 hours a day. In addition to its programming on the cable channel, TWC also provides forecasts for terrestrial and satellite radio stations, newspapers, and websites, and maintains an extensive online presence at weather.com.
Tornadoes are violent storms that come from powerful thunderstorms. They appear as a funnel- or cone-shaped cloud with winds that can reach up to 300 miles per hour. They cause damage when they touch down on the ground. They can damage an area one mile wide and 50 miles long. Tornado season commonly occurs during the months of March through August, but they can occur at any time. They can happen in any state but are most commonly found in Arkansas, Iowa, Kansas, Louisiana, Minnesota, Nebraska, North Dakota, Ohio, Oklahoma, South Dakota, and Texas - an area of which is commonly called "Tornado Alley". If there are weather or news reports that say there is a tornado in your area, the most important thing to do is to take shelter immediately in a place without windows, such as a bathroom or a basement. "Tornado" was a 14th-century sailor's word for a violent, windy thunderstorm. It may come from the Spanish word tronada, meaning "thunderstorm."
Earthquakes are the shaking, rolling or sudden shock of the earth’s surface.
Earthquakes happen along cracks (called fault lines) in the earth's surface. Earthquakes can be felt over large areas although they usually last less than one minute.
Earthquakes cannot be predicted -- although scientists are working on it! Earthquakes are measured by something called a Richter scale. While earthquakes are common on the West Coast, they can occur in 45 states and territories across the United States.
In an earthquake, remember to DROP, COVER and HOLD ON. DROP to the floor and get under something for COVER and HOLD ON until the shaking stops. Earthquakes are sometimes called temblors, quakes, shakers or seismic activity. In 1280, "earthquakes" were called "eorthequakynge".
Fires are unexpected events that can happen anywhere at school, at home, in a store or shopping mall or even in the outdoors in a forest or field. It is important to always know where the emergency exits are and to remember to be calm during a fire emergency. The most important thing you can do during a fire is listening to the direction of adults around you, like your teacher or parent. Remember to use the stairs (NEVER use an elevator) to leave the building or fire area right away and then call 911.
At Yellowstone National Park, the average time when fires are reported is 3:03 in the afternoon! This is because fires burn more vigorously during the middle of the day when the sun is very hot. These smoky fires are easily seen and often reported by park visitors!
Flooding happens during heavy rains, when rivers overflow, when ocean waves come onshore, when snow melts too fast or when dams or levees break. This is the most common natural weather event and can happen in every U.S. state. Flooding may be only a few inches of water or it may cover a house to the rooftop. Floods that happen very quickly are called flashfloods. It can happen in every U.S. state and territory. Stay as far away from flood water as you can. Moving flood water can be dangerous because it can knock you off your feet. And any type of flood water can be contaminated, meaning it can contain dangerous substances. The word "flood" comes from Old English and means "a flowing of water, river or sea."
Important Terms To Know:
Flood Watch or Flashflood Watch -- Flooding may happen soon. Stay tuned to the radio or television news for more information. If you hear a flashflood warning, talk to an adult immediately!
Flood Warning -- You may be asked to leave the area. A flood may be happening or will be very soon. Tell an adult if you hear a flood warning.
If you have to leave the area, remember to bring your Disaster Supply Kit and make arrangements for your pets.
Flashflood Warning -- A flashflood is happening. Get to high ground right away. Tell an adult!
A tsunami (pronounced soo-nahm-ee) is a series of giant waves that happen after underwater movement due to a variety of natural events such as earthquakes, volcanic eruptions, landslides and meteorites. The waves travel in all directions from the area of disturbance, much like the ripples that happen after throwing a rock. The waves may travel in the open sea as fast as 450 miles per hour.
As the big waves approach shallow waters along the coast they grow to a great height and smash into the shore. They can be as high as 100 feet. They can cause a lot of destruction on the shore. Tsunamis generally appear in the Pacific Ocean. Hawaii is the state at greatest risk for a tsunami. They get about one a year, with a damaging tsunami happening about every seven years. Alaska is also at high risk. California, Oregon and Washington experience a damaging tsunami about every 18 years.
If you feel an earthquake in the Pacific Coast area, turn on your battery-powered radio to learn if there is a tsunami warning. If you hear a tsunami warning, and they say to evacuate, do this immediately. "Tsunami" is a Japanese word. Tsu means "harbor" and nami means "wave."
Hurricanes are severe tropical storms that form in the southern Atlantic Ocean, Caribbean Sea, Gulf of Mexico and in the eastern Pacific Ocean. Hurricanes gather heat and energy through contact with warm ocean waters.
Evaporation from the seawater increases their power. Hurricanes rotate in a counter-clockwise direction around an "eye." Hurricanes have winds at least 74 miles per hour.
When hurricanes come onto land, their heavy rain, strong winds and large waves can damage buildings, trees and cars. The heavy waves are called a storm surge. Storm surges are very dangerous and it is important to take shelter during a hurricane and listen to the television or radio for instructions. "Hurricane" comes from the Spanish word huracan.