Narrow-bandwidth television
Narrow-bandwidth television (NBTV) is a type of television designed to fit into a low-bandwidth channel, in the extreme case using amateur radio voice frequency channels that only range up to a few kilohertz (though channels ranging into a few tens of kilohertz and beyond can also be used). This is in contrast to regular TV systems that use a channel about six megahertz wide. There are two ways to make this work: reduce the scan rate, or reduce the image size. When the scan rate is reduced, this is referred to as slow-scan TV. This article mostly deals with the latter type, where the number of lines in an image may be reduced to just a few dozen.
The earliest mechanical television systems often used narrow channels for sending moving images. Often, the images were only a few dozen lines in size. There is some interest in re-creating some of these old devices, both for the historical perspective and for the technical challenge. However, narrow-bandwidth TV does not require mechanical TV hardware. Computers and other electronic systems can be used instead.
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Categories: Television technology