| 摘要 |
In a digital information reproducing apparatus in which a clock signal can be recovered stably when reproduced digital information signals are detected by utilizing a partial response (PR) class 4 detection method, a digital information signal reproduced from a magnetic tape is equalized into a PR (1, -1) signal by means of an equalizer circuit, then equalized eventually into the PR class 4 signal by means of a (1+D) operation circuit and supplied to a ternary discriminator circuit to provide original digital information. A signal equalized into the PR (1, -1) signal and delivered out of the equalizer circuit is supplied to a clock component extractor circuit comprised of, for example, two squaring circuits, and a signal spectrum is generated in which a bright-line spectrum of high level develops at a bit frequency component of the reproduced digital information signal. The signal spectrum is supplied to a PLL circuit and a clock signal phase-locked to the bit frequency component can be obtained.
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