NTSC video is a full motion video format in which 60 interlaced fields (or pictures) of 262.5 horizontal lines are drawn on the receiving television or monitor per second. This results in 30 complete pictures transmitted per second. These lines are drawn by an electron beam striking a phosphor coating on the inside of the television screen. The beam is deflected (or "steered") by magnetic fields created by a deflection yoke on the back of the television's cathode ray tube. The NTSC video signal is a complicated waveform consisting of synchronization (both horizontal and vertical) to keep the receiver's electron gun in the right place, luminance, which is the continuously varying basic picture definition, and chrominance, or the color hue and saturation information. The video signal occupies a bandwidth of about 4 MHz.
NTSC video is send by amplitude-modulating the video transmitter, which results in a carrier and two identical sidebands. It was discovered early in the development of television that the home receiver could properly detect the signal if the carrier and only one sideband was transmitted. Therefore to save valuable frequency spectrum, only a part (or vestige) of the lower sideband is transmitted, hence the name vestigial sideband. The sound is sent by wide-band frequency modulating a carrier that is one-tenth the strength of the video carrier and exactly 4.5 MHz above it. The 75 microsecond pre-emphasized audio deviates the carrier +/- 25 kHz. The audio bandwidth is 30 to 15,000 Hz. The bandwidth of one channel including picture and sound is 6 MHz.