Electrical computers: arithmetic processing and calculating – Electrical analog calculating computer – Particular function performed
Reexamination Certificate
1998-09-11
2001-05-15
Mai, Tan V. (Department: 2121)
Electrical computers: arithmetic processing and calculating
Electrical analog calculating computer
Particular function performed
Reexamination Certificate
active
06233598
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to methods and apparatus for detecting data, and more particularly to, interleaved finite impulse response (FIR) filter functions for servo and data detection in a direct access storage device.
DESCRIPTION OF THE RELATED ART
Direct access storage devices (DASDs) often incorporating stacked, commonly rotated rigid magnetic disks are used for storage of data in magnetic form on the disk surfaces. Data is recorded in concentric, radially spaced data information tracks arrayed on the surfaces of the disks. Transducer heads driven in a path toward and away from the drive axis write data to the disks and read data from the disks. Typically servo information is provided on one or more disk surfaces for reading by the transducer heads for accurately and reliably positioning transducer heads on the disk surfaces at a specific location to read and write data.
As channel speeds go faster, conventional arrangements of circuit functions can be a limiting factor in overall performance. In the design of new DASDs, the performance requirements can be more demanding than the channel can deliver with traditional architectures.
A need exists for an improved, faster finite impulse response (FIR) filter apparatus for servo and data detection in a direct access storage device.
SUMMARY OF THE INVENTION
A principal object of the present invention is to provide an interleaved finite impulse response (FIR) filter apparatus for data detection in a direct access storage device. Other important objects of the present invention are to provide such interleaved finite impulse response (FIR) filter apparatus substantially without negative effects; and to provide such interleaved finite impulse response (FIR) filter apparatus that overcome some of the disadvantages of prior art arrangements.
In brief, an interleaved finite impulse response (FIR) filter apparatus is provided for data detection in a direct access storage device. The FIR filter includes a plurality of sample and hold circuits. Each sample and hold circuit samples an input signal sequentially at a clock rate. At least one set of multiple multipliers is coupled to the plurality of sample and hold circuits. Each multiplier multiplies a sample by a predefined value and provides a multiplier product at the clock rate. At least a pair of summing functions are coupled to the set of multipliers. Each summing function adds a predetermined combination of respective multiplier products and provides at least a pair of interleave outputs. Each of the interleave outputs is provided at less than the clock rate.
REFERENCES:
patent: 4691292 (1987-09-01), Rothweiler
patent: 4777612 (1988-10-01), Tomimitsu
patent: 4866647 (1989-09-01), Farrow
patent: 5438532 (1995-08-01), Nagao et al.
patent: 5563819 (1996-10-01), Nelson
patent: 5931899 (1999-08-01), Kertis
International Business Machines - Corporation
Mai Tan V.
Pennington Joan
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