VIDEO ON MAGNETIC TAPE
The use of magnetic tape to record and replay video signals is now commonplace, but the techniques involved are not so straightforward as for audio recording. The main problem is the relatively large bandwidth of the video signal, which for a broadcast-standard signal extends from d.c. (about 25 Hz in practice) to 5.5 MHz. For domestic videorecorders a more limited response is adequate – the h.f. roll-off occurs at about 2.5 MHz, permitting a more sparing use of the tape.
A magnetic tape system’s output level is proportional to the rate of change of the magnetic flux, so that output is directly geared to frequency. Thus each halving of frequency (octave) halves the output signal, giving the tape/head interface ...
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