AN ALL-DIGITAL BIT DETECTOR FOR COMPACT-DISK PLAYERS

A bit detector is described which is suitable for integration using digital VLSI technology. In the bit detector the signal is sampled at a fixed clock frequency which is not related to the bit rate of the input signal. The incoming bits are detected by comparing to the digitized input signal with the output of an all-digital PLL, which regenerates the bit clock that is present in the input signal. The design must be sufficiently robust to handle deviations in the physical size of the pits and disturbances like dropouts. Experimental optimization of the bit detector is performed with the aid of a hardware realization.