【発明の名称】クロツクパルス発生器同期用装置

Japanese Patent JPS6035863

B2

During the reading of serial data signals, for example, from a so-termed magnetic floppy disc, a synchronized condition between the local oscillator of the reading device and the timing of the data stream must be reached as quickly as possible after the start of the read operation. When the initial synchronization has been reached, readjustment of phase and frequency may take place only slowly, because the instants at which the actual signal transitions occur may exhibit a large spread with respect to the nominal instants. Therefore, during a synchronization operation an element of a read clock pulse train is applied to the phase comparator at each status transition of the medium as well as at further instants. The data sample signal of the clock pulse generator is applied at twice the bit frequency to the other input of the phase comparator. As a result, during the synchronization operation the phase comparison is performed in a dense series, so that the low-pass filter connected to the output of the phase comparator may have a high cut-off frequency. Once the synchronization has been realized, the phase comparison is performed only once per data bit and, the low-pass filter is switched over to a lower cut-off frequency.

MIROSURABU JANAKU
MARUCHIN GIUSUBERUKU
ARUBUREHITO RAINERUSU

JP1794380A

August 16, 1985

February 18, 1980

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FUIRITSUPUSU FURUUIRANPENFUABURIKEN NV

G11B5/09; G11B20/14; H04L7/00; H04L7/02; H04L7/033; (IPC1-7): H04L7/02; G11B20/14

Akihide Sugimura

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