Video Recording

The baseband (original) frequencies contained in a video signal lie between 10 Hz and 5 MHz. For a given bandwidth, assuming a simple, linear motion of the tape over a stationary recording head, the speed of the tape would be given by:

Speed of tape (meters per second) = width of gap (meters) × 2 × frequency (Hertz).

For a 5-MHz bandwidth and gap width of 1 × 10^-6 meters, the speed of the tape required would thus be 10 m per second, and 36,000 meters (over a mile) of tape would be needed to record a one-hour program. In practice, a linear tape speed for recording video signals of 24 mm per second can be achieved using various techniques. Some of the recording techniques used in the past and others currently in use are discussed in the following sections.