CUE SIGNAL GENERATOR
PURPOSE:To reduce noise on a screen due to a cue signal for program search by adding an erasing signal as a bias signal to the output of a sine-wave generating circuit, and recording the resulted output by a full-erasing head to the overall width of a magnetic tape. CONSTITUTION:A 3.58MHz color subc...
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Sprache: | eng |
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Zusammenfassung: | PURPOSE:To reduce noise on a screen due to a cue signal for program search by adding an erasing signal as a bias signal to the output of a sine-wave generating circuit, and recording the resulted output by a full-erasing head to the overall width of a magnetic tape. CONSTITUTION:A 3.58MHz color subcarrier signal is frequency-divided by 59,718 at a frequency dividing circuit 7 and further frequency-divided by two to generate a 30Hz rectangular wave, which is used by a sine wave generating circuit 1 to generate a sine wave; and the sine wave and the output of an erasing signal generating circuit 2 for generating an erasing signal which is used in video recording are added together and amplified by an amplifying circuit 4, whose output is applied to the full-erasing head 5 to record it as a cue signal to the overall width of the magnetic tape. The length of the signal is controlled by the sine wave generating circuit 1 by using the output signal of a High signal generating circuit 8 which goes up to a level Hight on the completion of loading to obtain a length equivalent to 0.5-1sec. As the cue signal is a sine wave, the variation in waveform with time is slow as compared with the differential waveform of the rectangular wave, a triangular wave, etc. and noise on the playback screen are reduced. |
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