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US 7,889,446 B2Granted
Baseline correction apparatus
AssigneeRohm Co., Ltd.
InventorsAtsushi Esumi, Kai Li, Hidemichi Mizuno
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Abstract
A read channel includes a variable gain amplifier, a low-pass filter, an AGC, an analog-to-digital converter, a frequency synthesizer, a filter, a soft-output detector, an LDPC decoding unit, a synchronizing signal detector, a run-length limited decoding unit, a descrambler, and a first baseline wander corrector. The first baseline wander corrector corrects a baseline variation by a feedforward control.
Claims6
A baseline correction apparatus comprising:
- an input unit which receives input of an analog-to-digital converted digital signal;
- a conversion unit which converts the digit signal inputted to said input unit, into a decision signal that takes any one of three values over time;
- a moving averaging unit which takes a moving average of the decision signal from said conversion unit;
- a decision unit which determines whether the decision signal is balanced over time or not, based on an output of said moving averaging unit;
- and
- a correction unit which corrects the signal from said input unit when the decision signal is not balanced over time or which does not correct the digital signal when the decision signal is balanced over time, based on an output of said decision unit,
- whereby said baseline correction apparatus corrects the baseline variation in the digital signal, and
- wherein said moving averaging unit is structured such that a different output is generated between
- in a first case where in the decision signals a middle value of the three values continues for a predetermined period or a difference between the numbers of two values opposite to each other with the middle value interposed therebetween is less than or equal to a predetermined number in the predetermined period, and
- in a second case where in the decision signals the difference between the numbers of two values opposite to each other with the middle value interposed therebetween is greater than or equal to the predetermined number in the predetermined period, and
- wherein, in the first case, said decision unit determines, based on an output of said moving averaging unit, that the value of the decision signal is balanced over time.
8 more elements
Dependencies are inferred from the claim text.