Narrow Bandwidth Television

The Narrow Bandwidth Television (narrow-band television, abbreviation NBTV ) originally emerged from an adaptation of the first television experiments in the 1920s and 1930s ( see also mechanical television) for amateur radio. The big advantage is that the television images in very low resolution, for example, in the still frequently encountered old English standard by John Logie Baird only 30 lines to 12.5 frames per second, respectively, in a now more common variant, the NBTV standard, is 32 lines. This results in a maximum requirement for the bandwidth of 32 lines x 48 pixels per row x 12.5 frames = 19,200 pixels, thus 9,600 Hertz. In practice, since less information is sent, a normal short-wave channel for transmission is sufficient, which makes this technique even today for amateur radio interesting. Although the images have a low resolution, but also moving images can be transferred as opposed to the higher -resolution SSTV.

The definition of the so-called NBTV standards is 32 lines, vertical, scanning from bottom right to top left ( non-interlaced ), aspect ratio 3:2 ( " portrait format"), 12.5 frames per second.

Today digital methods are used for the transmission and recording of color images, they are again decomposed into the three primary colors and to play either on the ( mechanical ) TV or transferred to a PC.

Regular broadcasts can, especially in the 80 meter band ( at 3700 kHz) in the AM modulation outside the usual " peak" hours are observed in some cases there are broadcasts in other frequency ranges and in pure digital form.

For decoding, and to generate the images are now often no specific televisions, but usually used computer. ( For digital forms of NBTV a computer is even a requirement. ) However, there are a growing number of fans and hobbyists mechanical and fully electronic television, which specifically use either historical receiver, or such ( partly under the help of modern means, such as light emitting diodes and transistor amplifiers ) rebuild.