In accordance with a method and apparatus of the present invention, a timing recovery device is disclosed to include a timing correction module responsive to a sampled input signal and adapted to generate a time-corrected signal and to further include a linear predictor coupled to the timing correction module for filtering the time-corrected signal to generate a whitened output signal and to further include a timing update module responsive to the whitened output signal for updating at least one parameter in the timing correction module.

Optimized timing recovery device and method using linear predictor

A digital magnetic recording system is described that doubles the linear data bit density of an existing head/medium interface. It uses the combination of the following three techniques: an efficient new run-length limited code (3PM), a special kind of ac-bias recording, and pulse slimming by write current shaping. The new code has the inherent potential of increasing linear data density over MFM by 50 percent. This potential can be fully utilized only if the analog waveshape is equalized to optimum spectral shaping. The present paper uses pulse slimming by double step write current shaping to achieve optimum equalization. Write current shaping requires linear operation. This is accomplished by ac-bias recording, assuring symmetrical single pulse shape that allows a large degree of pulse slimming. The parameters of ac-bias recording are chosen so that large signal amplitude is used. This, in conjunction with write current shaping, maximizes signal-to-noise ratio in the read channel, further increasing the bit density. An additional increase is realized by using a low inductance head that yields narrow PW50 value. The combination of all these factors results in 8000 BPI density on the original 4000 BPI MFM system.

http://ieeexplore.ieee.org/iel5/20/25799/01145879.pdf

High Density Recording with Write Current Shaping

An interest in the application of communication techniques to the recovery of information from magnetic recording has lead to an investigation of clock synchronization for these channels. The work presented here demonstrates a means of extracting clocking information using a lattice linear predictor on a received digital data stream, such as seen from a recording channel. The lattice linear predictor accurately follows the transient behavior of the digital symbols and isolates the symbols to form a sync signal suitable for driving a phase-locked-loop. The supression of noise using this technique enables the bandwidth of the locked oscillator to be sufficient to allow rapid tracking of the varying data rate associated with magnetic readback signals.

M. Larimore

Papers

Recursive linear prediction for clock synchronization