| 摘要 |
PURPOSE: A data back-up apparatus using full bandwidth of a composite video signal is provided to modulate the frequency of a luminance signal with an extended frequency band as a frequency band for a color signal at a data back-up so that many more back-up data are stored to a video tape having the same time length and also use a frequency modulating portion in common as selecting a modulation frequency varying portion varying a modulation frequency in the frequency modulation of a luminance signal. CONSTITUTION: The data back-up apparatus includes a data modulating portion(10), a luminance signal/color signal dividing portion(20), first and second signal switching portions(30a,30b), a low band converting portion(40), a frequency modulating portion(60), a modulation frequency varying portion(65) and a magnetic recording portion(80). The data modulating portion receives the back-up data for making back-up according to selection of a data back-up mode to store a back-up data and modulates into a form of a composite video signal to generate a pseudo composite video signal. The luminance signal/color signal dividing portion divides a real luminance signal from a real color signal in the real composite video signal according to selection of a recording mode to record the real composite video signal. The first signal switching portion switches an output of the data modulating portion when the data back-up mode is selected and the divided real luminance signal to the luminance signal/color signal dividing portion when the recording mode is selected. The low band converting portion converts the real color signal divided from the luminance signal/color signal dividing portion into a low frequency band. The second signal switching portion switches an output of the low band converting portion when the recording mode is selected and the ground when the data back-up mode is selected. The frequency modulating portion receives an output of the first signal switching portion and modulates frequency into the first frequency band modulation when the recording mode is selected and receives an output of the first signal switching portion and modulates frequency into the second frequency band summed the first frequency band and the low frequency band when the data back-up mode is selected. The modulation frequency varying portion is combined to the frequency modulating portion and converts the modulation frequency of the frequency modulating portion into the first frequency band and the second frequency band respectively as varying a resistance value corresponding to selection the recording mode and the data back-up mode. The magnetic recording portion overlays an output of the low band converting portion and an output of the second signal switching portion to record in a video tape.
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