Synchronisation circuit for optical disc playback - has multiple synchronisation signals used together with PLL to provide operation when information is damaged.

摘要

The playback system for an optical disc using signal contained within sectors on the disc tracks. Each sector contains a number of synchronisation samples that are used in a phase locked loop circuit. The synchronisation circuit has a PLL stage (16) providing a playback clock signal (REP CLK) and uses an input clock (REF CLK) and a digital signal. The circuit responds to a READ GATE signal generated by a circuit consisting of 3 RS latches (17-19), a counter (8) and a processor (23). The counter provides the necessary timing signals for circuit operation. USE/ADVANTAGE - Provides reliable playback of information even when part of synchronising pattern is damaged, e.g. disc is scratched.