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Test Card C
The following is a list of test cards used by the BBC at various points in broadcasting. Tuning Signals The first "Interval signal, Tuning Signals" test card was broadcast by the BBC in 1934. It was a simple line and circle broadcast using John Logie Baird, Baird's Mechanical television, 30-line system, and was used to synchronise the mechanical scanning system. Test Card A Test Card A made its debut in 1937. However, it and Test Card B were soon replaced by the more useful Test Card C. Test Card B Test Card B was an early BBC television test card. It was very similar to Test Card A but was never broadcast, possibly used by BBC engineers for internal use. The original card has since gone missing. The only difference was it had an extra greyscale stripe below the circle. The letter box in Test Card A was moved to the top of the card. Test Card C Test Card C was a BBC television test card first broadcast in 1948. It was the first test card to resemble the famous Test Card F. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Test Card
A test card, also known as a test pattern or start-up/closedown test, is a television test signal, typically broadcast at times when the transmitter is active but no program is being broadcast (often at sign-on and sign-off). Used since the earliest TV broadcasts, test cards were originally physical cards at which a television camera was pointed, allowing for simple adjustments of picture quality. Such cards are still often used for calibration, alignment, and matching of cameras and camcorders. From the 1950s, test card images were built into monoscope tubes which freed up the use of TV cameras which would otherwise have to be rotated to continuously broadcast physical test cards during downtime hours. Electronically generated test patterns, used for calibrating or troubleshooting the downstream signal path, were introduced in the late-1960s. These are generated by test signal generators, which do not depend on the correct configuration (and presence) of a camera, and can also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
