| 摘要 |
A circuit capable of simply writing a specified modulation signal, for example, eight to fourteen modulated signals onto a writable optical disk, by utilizing rising and falling edges of the signal. The circuit includes a first pulse generator for generating a first write pulse upon each rising edge of the first format of modulation signal; a second pulse generator for generating a second write pulse upon each falling edge of the first format of modulation signal; a gating circuit for providing either one of the first and second pulses, in sequence of occurrence, to a laser power controller, so as to enable to write the first format of modulation signal onto the disk; a signal reproducing circuit for reproducing the first format of modulation signal retrieved from the disk into the original modulation signal; and a switching circuit for selecting either one of the second type of reproduced modulation signal and output of the signal reproducing circuit for a demodulating circuit. The circuit makes it possible to write an EFM signal by two successive write pulses, irrespectively of the length of logic high duration of the EFM signal.
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