Digital recorded data reproducing device

A digital recorded data reproducing device comprising:

• an analog/digital converting means for sampling a reproduction signal of a recording medium to digital data asynchronously with a phase of a clock component included in the signal;
• a digital data correction means for correcting an offset component and an amplitude from the sampled signal;
• an equalizing filter for subjecting the corrected signal to a partial response equalization;
• a phase-locked loop for detecting a phase error based on an output signal of the equalizing filter;
• a filter factor control means for adaptively controlling a filter factor of the equalizing filter so that an equalization error is minimum based on the output signal of the equalizing filter as well as controlling the filter factor so that there is no phase error based on an output of the phase-locked loop;
• and
• a maximum likelihood decoder for performing a maximum likelihood decoding according to a type of partial response at equalization by the equalizing filter so as to perform a data demodulation.

A digital recorded data reproducing device comprising:

• a preamplifier for emphasizing an output amplitude of a reproduction signal from a recording medium;
• a waveform equalizing means for emphasizing a prescribed frequency band of the emphasized signal;
• an analog/digital converting means for sampling the equalized signal to a digital data with multiple bits asynchronously with a phase of a clock component included in the signal by a clock generated by an oscillator;
• an offset correction means for decreasing an offset component from the sampled signal;
• an automatic gain control means for adjusting the amplitude of the output signal to a required level;
• a transversal filter for subjecting the signal subjected to the amplitude adjustment to a partial response equalization;
• a high-order interpolation filter for reproducing a signal in a regular sampling phase from the signal subjected to the partial response equalization by a high-order interpolation;
• a tap weighting factor control means for controlling a tap weighting factor of the transversal filter from the interpolation output signal adaptively so that an equalization error is minimum;
• a phase comparator for detecting a phase error from the interpolation output signal;
• a loop filter for smoothing the phase error signal;
• and
• a maximum likelihood decoder for subjecting the interpolation output signal to a maximum likelihood decoding according to a type of partial response at equalization by the transversal filter so as to perform a data demodulation, wherein
• the asynchronously sampled signal is subjected to the partial response equalization, and a phase synchronization is compensated by a phase-interpolation-type digital phase-locked loop so that a data demodulation is performed.

A digital recorded data reproducing device comprising:

• a preamplifier for emphasizing an output amplitude of reproduction signal from a recording medium;
• a waveform equalizing means for emphasizing a prescribed frequency band of the emphasized signal;
• an analog/digital converting means for sampling the equalized signal to a digital data with multiple bits asynchronously with a phase of a clock component included in the signal by a clock generated by an oscillator;
• an offset correction means for decreasing an offset component from the sampled signal;
• an automatic gain control means for adjusting the amplitude of the output signal to a required level;
• a phase-interpolation-type transversal filter, which has functions of a transversal filter and a high-order interpolation filter together, for subjecting the signal subjected to the amplitude adjustment to a partial response equalization and reproducing a signal in a regular sampling phase from the signal subjected to the partial response equalization by a high-order interpolation;
• a phase comparator for detecting a phase error from the output signal;
• a loop filter for smoothing the phase error signal to obtain phase information;
• a tap weighting factor setting means for setting a weighting factor of a tap of the phase-interpolation-type transversal filter which makes an equalization error minimum and is for reproducing a normal sampling signal from the phase information and the output signal of the phase-interpolation-type transversal filter;
• and
• a maximum likelihood decoder for subjecting the interpolation output signal to a maximum likelihood decoding according to a type of partial response at equalization by the phase-interpolation-type transversal filter so as to perform a data demodulation, wherein
• the partial response equalization and a digital phase-locked loop are realized by the same filter.

A digital recorded data reproducing device comprising:

• a preamplifier for emphasizing an output amplitude of a reproduction signal from a recording medium;
• a waveform equalizing means for emphasizing a prescribed frequency band of the emphasized signal;
• an analog/digital converting means for sampling the equalized signal to a digital data with multiple bits asynchronously with a phase of a clock component included in the signal by a clock generated by an oscillator;
• an offset correction means for decreasing an offset component from the sampled signal;
• an automatic gain control means for adjusting the amplitude of the output signal to a required level;
• a transversal filter for subjecting the signal subjected to the amplitude adjustment to a partial response equalization;
• a high-order interpolation filter for reproducing a signal in a regular sampling phase from the signal subjected to the partial response equalization by a high-order interpolation;
• a tap weighting factor control means for controlling a tap weighting factor of the transversal filter from the interpolation output signal adaptively so that an equalization error is minimum;
• a phase comparator for detecting a phase error from the interpolation output signal;
• and
• a loop filter for smoothing the phase error signal;
• and
• a maximum likelihood decoder for subjecting the interpolation output signal to a maximum likelihood decoding according to a type of partial response at equalization by the transversal filter so as to perform a data demodulation, as well as comprising:
• a frequency control means for performing a control based on a cycle of a synchronization pattern included in recording data and a time width with which the synchronization pattern is detected;
• a phase synchronization maintaining means for monitoring a control range of the loop filter after a frequency and a frequency of a clock component included in the reproduction signal are pulled in to the neighborhood and performing an up/down control of a clock frequency so that the phase control signal returns to a normal operating range before the signal reaches an area out of phase synchronization control;
• and
• an oscillator control means for controlling the oscillator based on an output signal of the frequency control means and an output signal of the phase synchronization maintaining means.

A digital recorded data reproducing device comprising:

• a preamplifier for emphasizing an output amplitude of a reproduction signal from a recording medium;
• a waveform equalizing means for emphasizing a prescribed frequency band of the emphasized signal;
• an analog/digital converting means for sampling the equalized signal to a digital data with multiple bits asynchronously with a phase of a clock component included in the signal by a clock generated by an oscillator;
• an offset correction means for decreasing an offset component from the sampled signal;
• an automatic gain control means for adjusting the amplitude of the output signal to a required level;
• a transversal filter for subjecting the signal subjected to the amplitude adjustment to a partial response equalization;
• a high-order interpolation filter for reproducing a signal in a regular sampling phase from the signal subjected to the partial response equalization by a high-order interpolation;
• a tap weighting factor control means for controlling a tap weighting factor of the transversal filter from the interpolation output signal adaptively so that an equalization error is minimum;
• a phase comparator for detecting a phase error from the interpolation output signal;
• a loop filter for smoothing the phase error signal;
• and
• a maximum likelihood decoder for subjecting the interpolation output signal to a maximum likelihood decoding according to a type of partial response at equalization by the transversal filter so as to perform a data demodulation, wherein
• the asynchronously sampled signal is subjected to the partial response equalization, and a phase synchronization is compensated by a phase-interpolation-type digital phase-locked loop so that a data demodulation is performed, as well as
• the offset correction means performs an offset correction with reference to the output of the high-order interpolation filter.