Phase tolerant servo gray code detector
AssigneeTexas Instruments Incorporated
InventorsRyohei Kuki, Isao Takigasaki
Life of this patent
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Abstract
Methods and apparatus are disclosed for detecting PR4 equalized Gray codes, providing phase tolerant Gray codes and detection thereof. A Gray code detector is provided, which receives a PR4 equalized Gray code input signal and provides a binary detector output. The detector comprises a plurality of filters providing Euclidean distance values based on the input signal. A logic component selectively provides the detector output based on one or more of the Euclidean distance values from the matched filters, according to one or more criteria, such as the detector mode.
Claims31
A Gray code detector for receiving a PR4 equalized Gray code input signal and providing a detector output, the detector comprising:
- first, second, and third filters providing first, second, and third Euclidean distance values, respectively, based on the input signal;
- a logic component providing the detector output based on at least one of the first, second, and third Euclidean distance values;
- and
- first, second, and third comparators providing first, second, and third comparison values, based on comparisons of the first, second, and third Euclidean distance values with first, second, and third threshold values, respectively, wherein the logic component provides the detector output based on at least one of the first, second, and third comparison values.
A Gray code detector for receiving a PR4 equalized Gray code input signal and providing a detector output, the detector comprising:
- first, second, and third filters providing first, second, and third Euclidean distance values, respectively, based on the input signal;
- and
- a logic component providing the detector output based on at least one of the first, second, and third Euclidean distance values;
- wherein the Gray code input signal comprises six bits Y−5, Y−4, Y−3, Y−2, Y−1, and Y0;
- wherein the first filter provides the first Euclidean distance value as (Y−5+Y−4−2Y−3−2Y−2+Y−1+Y0);
- wherein the second filter provides the second Euclidean distance value as (Y−5−Y−4−Y−3);
- and
- wherein the third filter provides the third Euclidean distance value as (−Y−2−Y−1+Y0).
A Gray code detector for receiving a PR4 equalized Gray code input signal and providing a detector output, the detector comprising:
- first, second, and third filters providing first, second, and third Euclidean distance values, respectively, based on the input signal;
- and
- a logic component providing the detector output based on at least one of the first, second, and third Euclidean distance values;
- wherein the Gray code input signal comprises gray code data represented by a rate 1/6 Gray code, wherein a gray code data “0” is represented in the Gray code as an NRZI code of “001000” and a PR4 code of “001100” or “00−1−100”, and wherein a gray code data “1” is represented in the Gray code as an NRZI code of “101010” and a PR4 code of “11−1−111” or “−1−111−1−1”.
A method of detecting a PR4 equalized rate 1/6 Gray code in an input signal, wherein a pray code data “0” is represented in the Gray code as an NRZI code of “001000” and a PR4 code of “001100”, and wherein a gray code data “1” is represented in the Gray code as an NRZI code of “10101” and a PR4 code of “11−1−111”, the method comprising:
- providing first, second, and third Euclidean distance values based on the input signal;
- and
- providing a detector output based on at least one of the first, second, and third Euclidean distance values,
- wherein the Gray code input signal comprises six bits Y−5, Y−4, Y−3, Y−2, Y−1, and Y0;
- wherein providing the first Euclidean distance comprises computing (Y−5+Y−4−2Y−3−2Y−2+Y−1+Y0);
- wherein providing the second Euclidean distance comprises computing (Y−5−Y−4−Y−3);
- and
- wherein providing the third Euclidean distance comprises computing (−Y−2−Y−1+Y0).
A method of detecting a PR4 equalized rate 1/6 Gray code in an input signal, wherein a gray code data “0” is represented in the Gray code as an NRZI code of “001000” and a PR4 code of “001100”, and wherein a gray code data “1” is represented in the Gray code as an NRZI code of “101010” and a PR4 code of “11−1−111”, the method comprising:
- providing first, second, and third Euclidean distance values based on the input signal;
- and
- providing a detector output based on at least one of the first, second, and third Euclidean distance values,
- wherein providing the detector output comprises:
- comparing the first, second, and third Euclidean distance values with first, second, and third threshold values to provide first, second, and third comparison values, respectively;
- providing the detector output based on the first Euclidean distance value when the detector is in a track mode;
- and
- providing the detector output based on a logical OR of the first, second, and third comparison values when the detector mode is a seek mode.
A mass storage device read channel, comprising:
- a circuit operative to receive data signals representing a Gray code from a storage medium;
- an equalizer circuit operative to modify the data signals to a PR4 target to produce a Gray code input signal;
- and
- a Gray code detector, comprising:
- first, second, and third filters providing first, second, and third Euclidean distance values, respective, based on the Gray code input signal;
- a logic component providing the detector output based on at least one of the first, second, and third Euclidean distance values;
- and
- first, second, and third comparators providing first, second, and third comparison values, based on comparisons of the first, second, and third Euclidean distance values with first, second, and third threshold values, respectively, wherein the logic component provides the detector output based on at least one of the first, second, and third comparison values.
Dependencies are inferred from the claim text.