Dynamic magnetic information storage or retrieval – General processing of a digital signal – Data clocking
Patent
1993-09-01
1995-04-11
Hajec, Donald
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Data clocking
360 61, G11B 509, G11B 1512
Patent
active
054064279
ABSTRACT:
In a clock generator for magnetic disk drive of the zone-bit recording type in which a training signal is written in a preamble portion of data, comprising: a sample-holder circuit for generating a sampling signal from a read signal; a phase-comparator for detecting a phase difference from the sampling signal; a loop filter; and a voltage-controlled oscillator whose frequency is controlled by the phase difference as it is smoothed; there is provided a frequency divider; a clock extraction circuit for extracting a clock timing from the training signal as it is equalized partially-response signal; and a phase-comparator for finding a phase difference from an output of the frequency divider and an output of the clock extraction circuit, and the phase-comparator is connected to the loop filter during reproduction of the preamble portion of the data and the phase-comparator is connected to the loop filter during reproduction of a data portion of the data by the switching of a change-over switch. As a result, hangup is prevented and an accurate clock timing in the clock generator.
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F. M. Gardner, "Hangup in Phase-Lock Loops", IEEE Transactions on Communications, vol. COM-25, No. 10, pp. 1210-1214 Oct. 1977.
Kurt H. Mueller & Markus Muller, "Timing Recovery in Digital Synchronous Data Receivers", IEEE Transactions on Communications, vol. COM-24, No. 5, pp. 516-531 May 1976.
Fujitsu Limited
Hajec Donald
Kim Won Tue C.
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