Systems and methods for recovering information from a defective medium
Various embodiments of the present invention provide systems and methods for data regeneration. For example, a system for regenerating data is disclosed. The system includes a media defect detector that is operable to identify a potential media defect associated with a medium from which an input signal is derived, an attenuation amplitude detector that generates an attenuation factor, and a data detector. The data detector includes a first data path and a second data path. The first data path includes a bank of two or more selectable noise prediction filters and the second data path includes a fixed noise prediction filter and the attenuation factor. The data detector processes a derivative of the input signal using the second data path when the potential media defect is indicated, and processes the derivative of the input signal using the first data path when a media defect is not indicated.
1. A method for regenerating data derived from a defective medium, the method comprising:
providing a data regeneration circuit, wherein the data regeneration circuit includes a first data path including a bank of two or more selectable noise prediction filters and a second data path including a fixed noise prediction filter;
receiving a data input, wherein the data input is derived from a medium;
identifying a media defect corresponding to the data input;
based at least in part on the identified media defect, asserting a media defect flag;
selecting the second data path for processing whenever the media defect flag is asserted;
determining an attenuation factor associated with the defective medium, wherein the attenuation factor is incorporated in the second data path; and
augmenting the data input by a derivative of the attenuation factor to regenerate the data.
2. The method of claim 1 , wherein at least one output from the second data path is non-zero.
3. The method of claim 2 , wherein the data input is represented as y, the attenuation factor is represented as η, the fixed noise prediction filter is represented as ƒ(0000), and an ideal filter is represented as IDEAL′(X 3 X 2 X 1 X 0 ), wherein the second data path yields an output represented as: [ƒ(0000)*y−η·IDEAL′(X 3 X 2 X 1 X 0 )] 2 /N0.
4. The method of claim 2 , wherein the data input is a first data input, wherein the method further comprises:
receiving a second data input, wherein the second data input is derived from the medium;
determining that the medium is non-defective at the location corresponding to the second data input; and
selecting the first data path for processing whenever the media defect flag is de-asserted.
5. The method of claim 1 , wherein the second data path includes a multiplier augmenting the processed data by a programmable scalar value.
6. The method of claim 1 , wherein an output of the second data path is multiplied by a programmable scalar value.
7. A system for regenerating data, the system comprising:
a media defect detector, wherein the media defect detector is operable to identify a potential media defect associated with a medium from which an input signal is derived;
an attenuation amplitude detector, wherein the attenuation amplitude detector generates an attenuation factor associated with the potential media defect;
a data detector, wherein the data detector includes a first data path and a second data path, wherein the first data path includes a bank of two or more selectable noise prediction filters and the second data path includes a fixed noise prediction filter and the attenuation factor, and wherein the data detector processes a derivative of the input signal using the second data path when the potential media defect is indicated by augmenting the data input by a derivative of the attenuation factor to regenerate data.
8. The system of claim 7 , wherein the data detector is a maximum a posteriori detector.
9. The system of claim 7 , wherein the data detector is a soft output Viterbi algorithm detector.
10. The system of claim 7 , wherein an output of the data detector is provided to a decoder, and wherein the decoder provides a decoded output reflecting a regenerated value of the input signal.
11. The system of claim 10 , wherein the decoder is a low density parity check decoder.
12. The system of claim 7 , wherein the data input is represented as y, the attenuation factor is represented as η, the fixed noise prediction filter is represented as ƒ(0000), and an ideal filter is represented as IDEAL′(X 3 X 2 X 1 X 0 ), wherein the second data path yields an output represented as: [ƒ(0000)*y−η·IDEAL′(X 3 X 2 X 1 X 0 )] 2 /N0.
13. The system of claim 7 , wherein the data detector processes a derivative of the input signal processed by the first data path when a media defect is not indicated.
14. The system of claim 7 , wherein the data detector processes the input signal without augmentation by the attenuation factor when the potential media defect is not indicated.
15. The system of claim 7 , wherein the system further includes a decoder circuit, and wherein an output of the data detector is provided to the decoder circuit.
16. The system of claim 15 , wherein the decoder circuit is an LDPC decoder circuit.
17. The system of claim 7 , wherein an output of the second data path is multiplied by a programmable scalar value.
18. The system of claim 7 , wherein the second data path includes a multiplier augmenting the processed data by a programmable scalar value.
19. A system for regenerating data, the system comprising:
a media defect detector, wherein the media defect detector is operable to identify a potential media defect associated with a medium from which an input signal is derived;
an attenuation amplitude detector, wherein the attenuation amplitude detector generates an attenuation factor;
a data detector, wherein the data detector includes a first data path and a second data path, wherein the first data path includes a bank of two or more selectable noise prediction filters and a second data path includes a fixed noise prediction filter and the attenuation factor, and wherein the data detector processes a derivative of the input signal processed by the second data path when the potential media defect is indicated;
wherein an output of the second data path is multiplied by a first programmable scalar value; and
wherein the first data path includes a multiplier augmenting the processed data by a second programmable scalar value.
20. The system of claim 19 , wherein the data detector is a maximum a posteriori detector.
21. The system of claim 19 , wherein the data detector is a soft output Viterbi algorithm detector.
22. The system of claim 19 , wherein an output of the data detector is provided to a decoder, and wherein the decoder provides a decoded output reflecting a regenerated value of the input signal.
23. The system of claim 22 , wherein the decoder is a low density parity check decoder.
24. The system of claim 19 , wherein the data input is represented as y, the attenuation factor is represented as η, the fixed noise prediction filter is represented as ƒ(0000), and an ideal filter is represented as IDEAL′(X 3 X 2 X 1 X 0 ), wherein the second data path yields an output represented as: [ƒ(0000)*y−η·IDEAL′(X 3 X 2 X 1 X 0 )] 2 /N0.
25. The system of claim 19 , wherein the data detector processes a derivative of the input signal processed by the first data path when a media defect is not indicated.
26. The system of claim 19 , wherein the data detector processes the input signal without augmentation by the attenuation factor when the potential media defect is not indicated.
27. The system of claim 19 , wherein the system further includes a decoder circuit, and wherein an output of the data detector is provided to the decoder circuit.
28. The system of claim 27 , wherein the decoder circuit is an LDPC decoder circuit.
29. The system of claim 19 , wherein the system is implemented as part of a data storage device.
30. The system of claim 19 , wherein the system is implemented as part of an integrated circuit.
31. The system of claim 7 , wherein the system is implemented as part of a data storage device.
32. The system of claim 7 , wherein the system is implemented as part of an integrated circuit.
33. A data processing circuit, the data processing circuit comprising:
a media defect detector operable to identify a potential defect on a medium from which an input signal is derived, and to assert a defect flag;
an attenuation amplitude detector operable to calculate an attenuation of the input signal and to provide an attenuation factor corresponding to the attenuation of the input signal; and
a data processor circuit operable to receive a processing input, wherein the processing input is derived from the input signal multiplied by the attenuation factor during a period when the defect flag is asserted;
wherein the input signal is represented as y, the attenuation factor is represented as η, the fixed noise prediction filter is represented as ƒ(0000), and an ideal filter is represented as IDEAL′(X 3 X 2 X 1 X 0 ), wherein the second data path yields an output represented as: [ƒ(0000)*y−η·IDEAL′(X 3 X 2 X 1 X 0 )] 2 /N0.
34. The circuit of claim 33 , wherein the data processor circuit is a data detector circuit.
35. The circuit of claim 34 , wherein the data detector circuit is selected from a group consisting of: a maximum a posteriori detector circuit, and a Viterbi algorithm detector circuit.
36. The circuit of claim 33 , wherein the circuit is implemented as part of a data storage device.
37. The circuit of claim 33 , wherein the circuit is implemented as part of an integrated circuit.
38. The circuit of claim 33 , wherein at least one instance ops the attenuation factor is non-zero.
39. The circuit of claim 33 , wherein the period is a first period, and wherein the processing input is the input signal during a second period when the defect flag is de-asserted.
40. The circuit of claim 7 , wherein at least one output from the second data path is non-zero.