Read read-only fields while writing
AssigneeSeagate Technology LLC
InventorsBarmeshwar Vikramaditya, Bruce Douglas Buch, Timothy Ellis
Life of this patent
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Abstract
A circuit may be configured to reduce the amount of space used on a storage device when a transducer having a reader and writer passes from a writable data field to a read-only field by enabling both the reader and writer simultaneously. The circuit can be configured to reduce to a threshold level the noise on a read signal that can occur when the reader is over a read-only field and the writer is over a writable data field, and can ignore the read data when both the writer and reader are enabled simultaneously over a writable data field.
Claims17
An apparatus comprising:
- a circuit including an adaptive least mean square (LMS) filter coupled to a finite impulse response (FIR) filter, the circuit configured to:
- receive a read signal via a read element of a transducer when the read element enters a read-only field;
- provide a write signal to a write element of the transducer when the write element is over a writable data field and the read element is in the read-only field;
- enable the FIR filter to determine an estimate of interference in the read signal, the estimate based on the write signal, during simultaneous operation of the write element and the read element;
- subtract the estimate of interference from the read signal to produce a filtered read signal;
- provide the filtered read signal to a detector when the noise of the read signal is above a threshold level;
- provide a non-filtered read signal when noise of the read signal is below the threshold level;
- and
- the adaptive LMS filter configured to program coefficients to the FIR filter based on noise remaining in the filtered read signal after subtraction of the estimate of interference, the program coefficients selected by the LMS filter to correct errors in the estimate of interference.
An apparatus comprising:
- a circuit including:
- a first input to receive write data from a write element, the write data obtained when the write element is over a writable data field and a read element is producing a read signal from a write-disabled field;
- a cancellation filter circuit adapted to:
- acquire a non-filtered read signal when noise of the read signal is below a threshold level;
- acquire a filtered read signal when the noise of the read signal is above the threshold level;
- the cancellation filter including:
- a finite impulse response (FIR) filter configured to produce an estimate of interference based on the write data, and the filtered read signal is based on the estimate of interference;
- an adaptive least mean square (LMS) filter coupled to the FIR filter, the adaptive LMS filter configured to program coefficients to the FIR filter based on noise in the filtered read signal, the program coefficients selected by the LMS filter to correct errors in the estimate of interference.
A method comprising:
- writing data via a write element when the write element is over a writable data field while a read element is generating a read signal by reading from a read-only field;
- estimating interference based on the write data;
- acquiring a non-filtered read signal when noise of the read signal is below a threshold level;
- acquiring a filtered read signal, based on the estimate of interference, when the noise of the read signal is above the threshold level;
- and
- programming coefficients via an adaptive least mean square (LMS) filter to a finite impulse response (FIR) filter based on noise in the filtered read signal, the program coefficients selected by the LMS filter to correct errors in the estimate of interference.
Dependencies are inferred from the claim text.