The original English version and the machine-translated Chinese version.
Narrow-band television, in a broad sense, refers to all methods of transmitting motion images with lower bandwidth, inheriting from the Bell Labs mechanical television. Unlike slow-scan televisions, narrow-band televisions transmit full motion images.
The bandwidth of narrow-band television (30 lines) is typically less than 15 kHz, but the sidebands are not sharply cut off. Adding a low-pass filter can further restrict the bandwidth of narrow-band television, but this reduces resolution (making the image blurry). This can be seen as the image passing through a low-pass filter. The BBC's previous narrow-band television broadcasts used a bandwidth below 4.5 kHz.
Narrow-band televisions can transmit both black and white images, as well as color images. The bandwidth is proportional to the frame rate, line count, number of colors, etc.
Commonly used line numbers are 30, 32, 60, and 120 lines. The scanning direction is also not fixed.
Malcolm Baird (the son of J. L. Baird, the father of mechanical television), wrote the preface to the NBTV manual in 2010 as Honorary Chairman of the Narrow Band Television Association.
I will write a short article introducing narrow-band television and mechanical scanning television.
Manual URL:http://www.nbtv.wyenet.co.uk/handbook.htm
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