BROADCASTING TELEVISION

Broadcasting

 1927, Baird transmitted a long-distance television signal over 438 miles (705 km) of telephone line between London and Glasgow; Baird transmitted the world's first long-distance television pictures to the Central Hotel at Glasgow Central Station.^[23] This transmission was Baird's response to a 225-mile, long-distance telecast between stations of AT&T Bell Labs. The Bell stations were in New York and Washington, DC. The earlier telecast took place in April 1927, a month before Baird's demonstration

Baird then set up the Baird Television Development Company Ltd, which in 1928 made the first transatlantic television transmission, from London to Hartsdale, New York, and the first television programme for the BBC. In November 1929, Baird and Bernard Natan established France's first television company, Télévision-Baird-Natan. He televised the first live transmission of the Epsom Derby in 1931. He demonstrated a theatre television system, with a screen two feet by five feet (60 cm by 150 cm), in 1930 at the London Coliseum, Berlin, Paris, and Stockholm. By 1939 he had improved his theatre projection system to televise a boxing match on a screen 15 ft (4.6 m) by 12 ft (3.7 m)

From 1929 to 1932, the BBC transmitters were used to broadcast television programmes using the 30-line Baird system, and from 1932 to 1935, the BBC also produced the programmes in their own studio at 16 Portland Place. On 3 November 1936, from Alexandra Palace located on the high ground of the north London ridge, the BBC began alternating Baird 240-line transmissions with EMI's electronic scanning system which had recently been improved to 405 lines after a merger with Marconi. The Baird system at the time involved an intermediate film process, where footage was shot on cinefilm which was rapidly developed and scanned. The trial was due to last 6 months but the BBC ceased broadcasts with the Baird system in February 1937, due in part to a disastrous fire in the Baird facilities at Crystal Palace. It was becoming apparent to the BBC that the Baird system would ultimately fail due in large part to the lack of mobility of the Baird system's cameras, with their developer tanks, hoses, and cables

Baird's television systems were replaced by the electronic television system developed by the newly formed company EMI-Marconi under Isaac Shoenberg, which had access to patents developed by Vladimir Zworykin and RCA. Similarly, Philo T. Farnsworth's electronic "Image Dissector" camera was available to Baird's company via a patent-sharing agreement. However, the Image Dissector camera was found to be lacking in light sensitivity, requiring excessive levels of illumination. Baird used the Farnsworth tubes instead to scan cinefilm, in which capacity they proved serviceable though prone to drop-outs and other problems. Farnsworth himself came to London to Baird's Crystal Palacelaboratories in 1936, but was unable to fully solve the problem; the fire that burned Crystal Palace to the ground later that year further hampered the Baird company's ability to compete

Baird made many contributions to the field of electronic television after mechanical systems had taken a back seat. In 1939, he showed colour television using a cathode ray tubein front of which revolved a disc fitted with colour filters, a method taken up by CBS and RCA in the United States. In 1941, he patented and demonstrated a system of three-dimensional television at a definition of 500 lines. On 16 August 1944, he gave the world's first demonstration of a fully electronic colour television display. His 600-line colour system used triple interlacing, using six scans to build each picture.^] In 1943, the Hankey Committee was appointed to oversee the resumption of television broadcasts after the war. Baird persuaded them to make plans to adopt his proposed 1000-line Telechrome electronic colour system as the new post-war broadcast standard. The picture quality on this system would have been comparable to today's HDTV (High Definition Television). The Hankey Committee's plan lost all momentum partly due to the challenges of postwar reconstruction. The monochrome 405-line standard remained in place until 1985 in some areas, and it was three decades until the introduction of the 625-line system in 1964 and (PAL) colour in 1967. A demonstration of large screen three-dimensional television by the BBC was reported in March 2008, over 60 years after Baird's demonstration

Baird's mechanical scanning did not cease with the development of electronic systems. Improved versions of mechanical scanning survive today in long wavelength infrared cameras used for military purposes, principally to provide night vision capability for fighter pilots. The picture from the camera is typically superimposed on the pilot's forward view by displaying it in the head up display. They have also found a use in airborne police helicopters providing, not only night vision, but the ability to detect heat sources (such as people) during the day. These systems do not use the disc of lenses that Baird used, but instead use discs of prisms to scan the image onto a cooled infrared detector. Electronic pick up tubes are unsuitable for this application because there is no suitable target material with a sensitivity to long wavelength infrared light. Further, the glass bulb is opaque to such wavelengths.