| 摘要 |
PURPOSE:To obtain an optional amplitude characteristics and to improve the drop in the resolution with simple constitution, by using a surface acoustic wave filter as the RF moldulator of a VTR. CONSTITUTION:Video signals from a terminal 12 are given to a modulator 14 where they are changed to modulated video signals by a prescribed frequency f1 from an oscillator 16 and sound signals from another terminal 18 are given to another modulator 20 where they are changed to modulated sound signals. The modulated video signals and modulated sound signals from the modulators 14 and 20 are supplied to the input of a surface acoustic wave filter 22 under a superimposed condition. The amplitude characteristic of the filter 22 is raised at the high-frequency side within the passing band as shown by the line A and performs high-frequency boosting on the video signals and its group delay frequency characteristics are almost flat as shown by the line B. Therefore, deterioration of the high-frequency component of the video signals caused by the frequency characteristic of a video tape itself is compensated and drop in the resolution is improved.
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