US5258940A — Distributed arithmetic digital filter in a partia…

Claim 1

Independent Claim 76 words

A finite impulse response (FIR) digital filter comprising: means for storing a plurality of partial sums of predetermined tap weights; means for receiving a fixed qualifier value; means for calculating a predetermined tap weight using selected ones of said stored partial sums and said received fixed value; means for calculating predetermined filter coefficients using said calculated predetermined tap weight and predefined ones of said stored partial sums; and means for storing said calculated predetermined filter coefficients.

Claim 2

Dependent Claim 76 words

A finite impulse response (FIR) digital filter comprising: means for storing a plurality of partial sums of predetermined tap weights; means for receiving a fixed qualifier value; means for calculating a predetermined tap weight using selected ones of said stored partial sums and said received fixed value; means for calculating predetermined filter coefficients using said calculated predetermined tap weight and predefined ones of said stored partial sums; and means for storing said calculated predetermined filter coefficients.

Claim 3

Dependent Claim 36 words

A finite impulse response (FIR) digital filter as recited in claim 1 wherein said partial sums storing means includes a random access memory (RAM) and said filter coefficient storing means includes a random access memory (RAM).

Claim 4

Dependent Claim 46 words

A finite impulse response (FIR) digital filter as recited in claim 1 wherein said stored plurality of partial sums of tap weights include a plurality of stored partial sums of predetermined odd tap weights and a plurality of stored partial sums of predetermined even tap weights.

Claim 5

Dependent Claim 34 words

A finite impulse response (FIR) digital filter as recited in claim 3 wherein a number of tap weights equals 10 and 4 partial sums of both predetermined odd and even tap weights are stored.

Claim 6

Dependent Claim 45 words

A finite impulse response (FIR) digital filter as recited in claim 4 wherein said fixed qualifier value includes a first fixed qualifier value K 1 used for calculating odd filter coefficients and a second fixed qualifier value K 2 used for calculating even filter coefficients.

Claim 7

Dependent Claim 56 words

A finite impulse response (FIR) digital filter as recited in claim 5 wherein said first fixed qualifier value K 1 is defined by T 1 -T 3 +T 5 -T 7 +T 9 and wherein said second fixed qualifier value K 2 is defined by T 2 -T 4 +T 6 -T 8 +T 10 .

Claim 8

Dependent Claim 34 words

A finite impulse response (FIR) digital filter as recited in claim 8 wherein said calculated predetermined filter coefficients include 32 values, each calculated value is stored in predetermined one of two 16×9-bit RAM locations.

Claim 9

Dependent Claim 20 words

A finite impulse response (FIR) digital filter as recited in claim 1 wherein said calculating means includes a 3-way adder.

Claim 10

Dependent Claim 72 words

A finite impulse response (FIR) digital filter as recited in claim 6 wherein said partial sum storing means includes a random access memory (RAM) having addressable storage locations, one addressable location for storing each of said partial sums of predetermined tap weights, and wherein said 3-way adder receives two of said stored partial sums read from selected RAM locations for calculating said predetermined tap weight and for calculating each predetermined filter coefficient.

Claim 11

Dependent Claim 152 words

A finite impulse response (FIR) digital filter comprising: random access memory means for storing a plurality of partial sums of predetermined odd tap weights and for storing a plurality of partial sums of predetermined even tap weights; means for receiving an odd fixed qualifier value and an even fixed qualifier value; adder means for calculating a predetermined odd tap weight and a predetermined even tap weight, said predetermined odd tap weight being calculated by adding two of said stored partial sums of predetermined odd tap weights and said received odd fixed value; said predetermined even tap weight being calculated by adding two of said stored partial sums of predetermined even tap weights and said received even fixed value; said adder means for calculating predetermined filter coefficients using said calculated predetermined tap weight and predefined ones of said stored partial sums; and random access memory means for storing said calculated predetermined filter coefficients.

Claim 12

Dependent Claim 152 words

A finite impulse response (FIR) digital filter comprising: random access memory means for storing a plurality of partial sums of predetermined odd tap weights and for storing a plurality of partial sums of predetermined even tap weights; means for receiving an odd fixed qualifier value and an even fixed qualifier value; adder means for calculating a predetermined odd tap weight and a predetermined even tap weight, said predetermined odd tap weight being calculated by adding two of said stored partial sums of predetermined odd tap weights and said received odd fixed value; said predetermined even tap weight being calculated by adding two of said stored partial sums of predetermined even tap weights and said received even fixed value; said adder means for calculating predetermined filter coefficients using said calculated predetermined tap weight and predefined ones of said stored partial sums; and random access memory means for storing said calculated predetermined filter coefficients.

Claim 13

Dependent Claim 27 words

A finite impulse response (FIR) digital filter as recited in claim 10 further including a counter for providing control signals including sign control to said adder means.

Claim 14

Dependent Claim 149 words

A direct access storage device of the type including a partial-response maximum-likelihood (PRML) data channel comprising: a housing; at least one disk mounted in said housing for rotation about an axis and having at least one disk surface for storing data; transducer means mounted for movement across said disk surface for reading and writing data to said disk surface; a digital filter in said PRML data channel coupled to said transducer means for filtering digital sample values, said digital filter including; means for storing a plurality of partial sums of predetermined tap weights; means for receiving a fixed qualifier value; means for calculating a predetermined tap weight using selected ones of said stored partial sums and said received fixed value; means for calculating predetermined filter coefficients using said calculated predetermined tap weight and predefined ones of said stored partial sums; and means for storing said calculated predetermined filter coefficients.

Claim 15

Dependent Claim 149 words

A direct access storage device of the type including a partial-response maximum-likelihood (PRML) data channel comprising: a housing; at least one disk mounted in said housing for rotation about an axis and having at least one disk surface for storing data; transducer means mounted for movement across said disk surface for reading and writing data to said disk surface; a digital filter in said PRML data channel coupled to said transducer means for filtering digital sample values, said digital filter including; means for storing a plurality of partial sums of predetermined tap weights; means for receiving a fixed qualifier value; means for calculating a predetermined tap weight using selected ones of said stored partial sums and said received fixed value; means for calculating predetermined filter coefficients using said calculated predetermined tap weight and predefined ones of said stored partial sums; and means for storing said calculated predetermined filter coefficients.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1996-11-01	1997-05-03	1997-11-02	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2000-11-01	2001-05-03	2001-11-02	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2004-11-01	2005-05-03	2005-11-02	$7700.00	Window Closed / Lapsed

Distributed arithmetic digital filter in a partial-response maximum-likelihood disk drive system

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