Asynchronous sampling digital detector system for magnetic and optical recording channels

摘要

A variable sampling-rate digital channel phase detector for reading synchronous data recordings from magnetic or optical media. All-digital implementation allows multiplexing of several parallel channels on a single monolithic chip for tape storage systems or other magnetic or optical data storage systems. The ASDD channel signal processing is entirely digital and includes A/D converter, digital filter and equalizer, digital differentiator and zero-crossing detector, peak amplitude estimator, zero-crossing qualifier and zero-crossing position (phase) estimator. The ASDD input is an analog waveform and the output includes two flags for qualified negative and positive waveform threshold-crossings and a digital signal encoding a waveform threshold-crossing position within the current sampling clock interval. The ASDD operates over a wide continuous range of channel data rates and provides accurate phase detection at relatively low sampling rates. It is suitable for monolithic CMOS implementation, which provides low power dissipation and small size.