Systems and methods for retimed virtual data processing
View Patent ↗Various embodiments of the present invention provide systems and methods for data processing system. As one example, a data processing circuit is described that includes an analog to digital converter, an online timing loop, and an offline timing loop. The analog to digital converter receives an analog input and provides a first series of data samples Each bit of the first series of data samples corresponds to the analog input at a time controlled by an updated sampling clock. The online timing loop modifies the updated sampling clock based at least in part upon a processed version of the first series of data samples.
1. A data processing system, the system comprising:
an analog to digital converter operable to receive an analog input and to provide a first series of data samples, wherein each bit of the first series of data samples corresponds to the analog input at a time controlled by an updated sampling clock;
an online timing loop operable to modify the updated sampling clock based at least in part upon a processed version of the first series of data samples; and
an offline timing loop operable to interpolate a derivative of the first series of data samples to yield a second series of data samples, wherein the second series of data samples mimics a series of data samples corresponding to the analog input that were sampled using a free running clock; and wherein the second series of data samples is interpolated to adjust each bit in accordance with an average frequency offset exhibited across the second series of data samples.
2. The system of claim 1 , wherein the system is implemented as part of a storage device.
3. The system of claim 2 , wherein the storage device comprises:
a read/write head assembly disposed in relation to a storage medium and operable to sense an information set on the storage medium and to yield a sensed signal, wherein the analog input is derived from the sensed signal.
4. The system of claim 3 , wherein the storage device further comprises:
an amplifier circuit operable to amplify the sensed signal to yield an amplified signal, wherein the analog input is derived from the amplified signal.
5. The system of claim 1 , wherein the system further comprises:
a data detector circuit operable to apply a data detection algorithm to a detector input derived from the first series of data samples to yield a third series of data samples; and
wherein the online timing loop is operable to modify the updated sampling clock based on a phase error value derived by comparing the detector input to the third series of data samples.
6. The system of claim 5 , wherein the data detector circuit is a maximum a posteriori data detector circuit.
7. The system of claim 5 , wherein the data detector circuit is a first data detector circuit, wherein the data detection algorithm is a first data detection algorithm, wherein the detector input is a first detector input, and wherein the offline timing loop includes:
a digital interpolator circuit operable to receive a second series of data samples and to provide an interpolated series of data samples;
a second data detector circuit operable to apply a second data detection algorithm to a second detector input derived from the interpolated series of data samples to yield a fourth series of data samples;
a phase detector circuit operable to determine a phase error by comparing the second detector input with the fourth series of data samples; and
a loop filter operable to filter the phase error to yield a phase offset value that governs a phase offset applied by the digital interpolator circuit.
8. The system of claim 7 , wherein the second detector input is the interpolated series of data samples.
9. The system of claim 7 , wherein the second detector input is a filtered version of the interpolated series of data samples.
10. The system of claim 1 , wherein the system is implemented as part of an integrated circuit.
11. A data processing system, the system comprising:
an online timing loop operable to modify an updated sampling clock based at least in part upon a processed version of a first series of data samples; and
an offline timing loop operable to interpolate a data set derived from the first series of data samples to yield a second series of data samples, wherein the second series of data samples mimics a series of data samples corresponding to an analog input that were sampled using a free running clock; and wherein the second series of data samples is interpolated to adjust each bit in accordance with an average frequency offset exhibited across the second series of data samples.
12. The system of claim 11 , wherein the system further comprises:
an analog to digital converter operable to receive the analog input and to provide the first series of data samples, wherein each bit of the first series of data samples corresponds to the analog input at a time controlled by the updated sampling clock.
13. The system of claim 12 , wherein the system is implemented as part of a storage device.
14. The system of claim 13 , wherein the storage device comprises:
a read/write head assembly disposed in relation to a storage medium and operable to sense an information set on the storage medium and to yield a sensed signal; and
an amplifier circuit operable to amplify the sensed signal to yield an amplified signal, wherein the analog input is derived from the amplified signal.
15. The system of claim 11 , wherein the system further comprises:
a data detector circuit operable to apply a data detection algorithm to a detector input derived from the first series of data samples to yield a third series of data samples; and
wherein the online timing loop is operable to modify the updated sampling clock based on a phase error value derived by comparing the detector input to the third series of data samples.
16. The system of claim 15 , wherein the data detector circuit is a maximum a posteriori data detector circuit.
17. The system of claim 15 , wherein the data detector circuit is a first data detector circuit, wherein the data detection algorithm is a first data detection algorithm, wherein the detector input is a first detector input, and wherein the offline timing loop includes:
a digital interpolator circuit operable to receive a second series of data samples and to provide an interpolated series of data samples;
a second data detector circuit operable to apply a second data detection algorithm to a second detector input derived from the interpolated series of data samples to yield a fourth series of data samples;
a phase detector circuit operable to determine a phase error by comparing the second detector input with the fourth series of data samples; and
a loop filter operable to filter the phase error to yield a phase offset value that governs a phase offset applied by the digital interpolator circuit.
18. The system of claim 17 , wherein the second detector input is selected from a group consisting of: the interpolated series of data samples, and a filtered version of the interpolated series of data samples.
19. The system of claim 11 , wherein the system is implemented as part of an integrated circuit.
20. The system of claim 17 , wherein the system further comprises:
a data decoder circuit operable to apply a data decoding algorithm to a decoder input and to provides a decoded output; and
an interleaver memory operable to provide either the fourth series of data samples or the third series of data samples as the decoder input depending upon whether online or offline processing is selected.
21. The system of claim 20 , wherein the data decoder circuit is a low density parity check decoder circuit.