US4032762A — Adjustable digital filter for high speed digital …

Claim 1

Independent Claim 325 words

An adjustable digital filter for use in a digital data transmission and receiving system for digitally filtering and equalizing a received data signal supplied to the filter as digital data samples x j at twice the baud rate of data transmission and including successive, alternating integer-baud and half-baud samples, comprising: a plurality of successive delay stages for storing successive said digital data samples, a corresponding plurality of adjustable tap gain means respectively associated with said plurality of delay stages, each receiving the samples currently stored in the respectively associated delay stages and a corresponding tap gain control as inputs thereto, and producing as an output thereof the product of the inputs thereto, means for summing the outputs of said tap gain means and producing a filtered and equalized output sample y j in each baud interval for the corresponding integer baud sample x j , means responsive to each sample y.sub. j for generating a corresponding estimated value l o D j representing an estimate of the value of a correctly equalized and filtered output sample y j , means responsive to said summing means and also responsive to said estimated value generating means for generating an error signal Y j = y j - l o D j , first means for adjusting the tap gain control inputs to each of the adjustable tap gain means associated with said delay stages storing integer baud samples of said succession of samples, as a function of said error signal Y j and said digital data samples x j , and second means for adjusting the tap gain control inputs to each adjustable tap gain means associated with a delay stage storing half-integer baud samples of said succession of samples as a function of the adjustment by said first adjusting means to the tap gain control input to the adjustable tap gain means associated with at least one integer baud sample storing delay stage respectively corresponding thereto.

Claim 2

Dependent Claim 325 words

An adjustable digital filter for use in a digital data transmission and receiving system for digitally filtering and equalizing a received data signal supplied to the filter as digital data samples x j at twice the baud rate of data transmission and including successive, alternating integer-baud and half-baud samples, comprising: a plurality of successive delay stages for storing successive said digital data samples, a corresponding plurality of adjustable tap gain means respectively associated with said plurality of delay stages, each receiving the samples currently stored in the respectively associated delay stages and a corresponding tap gain control as inputs thereto, and producing as an output thereof the product of the inputs thereto, means for summing the outputs of said tap gain means and producing a filtered and equalized output sample y j in each baud interval for the corresponding integer baud sample x j , means responsive to each sample y.sub. j for generating a corresponding estimated value l o D j representing an estimate of the value of a correctly equalized and filtered output sample y j , means responsive to said summing means and also responsive to said estimated value generating means for generating an error signal Y j = y j - l o D j , first means for adjusting the tap gain control inputs to each of the adjustable tap gain means associated with said delay stages storing integer baud samples of said succession of samples, as a function of said error signal Y j and said digital data samples x j , and second means for adjusting the tap gain control inputs to each adjustable tap gain means associated with a delay stage storing half-integer baud samples of said succession of samples as a function of the adjustment by said first adjusting means to the tap gain control input to the adjustable tap gain means associated with at least one integer baud sample storing delay stage respectively corresponding thereto.

Claim 3

Dependent Claim 75 words

An adjustable digital filter as recited in claim 1 wherein said second means adjust the tap gain control inputs to each of the adjustable tap gain means associated with said delay stages storing half-integer baud samples as a function of the adjustments by said first adjusting means of the tap gain control inputs to the said next adjacent integer baud sample storing delay stage in at least a current and a preceding baud time interval.

Claim 4

Dependent Claim 83 words

An adjustable digital filter as recited in claim 1 wherein said second means adjust the tap gain control inputs to each of the adjustable tap gain means associated with said delay stages storing half-integer baud samples as a function of the adjustments by said first adjusting means of the tap gain control inputs to at least the respectively preceding and succeeding next adjacent integer baud sample storing delay stages of said successive delay stages for each said half-integer baud sample storing delay stage.

Claim 5

Dependent Claim 94 words

An adjustable digital filter as recited in claim 3 wherein said second means adjust the tap gain control inputs to each of the adjustable tap gain means associated with said delay stages storing half-integer baud samples as a function of the adjustments by said first adjusting means of the tap gain control inputs to at least the respectively preceding and succeeding next adjacent integer baud sample storing delay stages of said successive delay stages in at least a current and a preceding baud time interval, for each said half-integer baud sample storing delay stage.

Claim 6

Dependent Claim 85 words

An adjustable digital filter as recited in claim 1 wherein said second means adjust the tap gain control inputs to each of the adjustable tap gain means associated with said delay stages storing half-integer baud samples as a function of the adjustments by said first adjusting means of the tap gain control inputs to at least the respectively two preceding and two succeeding next adjacent integer baud sample storing delay stages of said successive delay stages for each said half-integer baud sample storing delay stage.

Claim 7

Dependent Claim 94 words

An adjustable digital filter as recited in claim 5 wherein said second means adjust the tap gain control inputs to each of the adjustable tap gain means associated with said delay stages storing half-integer baud samples as a function of the adjustments by said first adjusting means of the tap gain control inputs to at least the respectively preceding and succeeding next adjacent integer baud sample storing delay stages of said successive delay stages in at least a current and a preceding baud time interval, for each said half-integer baud sample storing delay stage.

Claim 8

Dependent Claim 281 words

An adjustable digital filter for use in a digital data transmission and receiving system for digitally filtering and equalizing a received data signal supplied to the filter as digital data samples x j at twice the baud rate of data transmission and including successive, alternating integer-baud and half-baud samples, comprising: means including a plurality of (2N- 1) successive delay stages for storing (2N- 1) successive ones of said digital data samples x j , a corresponding plurality of adjustable tap gain means respectively associated with said plurality of delay stages, each receiving the sample currently stored in the respectively associated delay stage and a corresponding tap gain control as inputs thereto, and producing as an output thereof the product of the inputs thereto, means for summing the outputs of said tap gain means and producing a filtered and equalized output sample y j in each baud interval for the corresponding integer-baud sample x j , means responsive to each sample y j for generating a corresponding, estimated value l o D j , means responsive to said summing means and also responsive to said estimated value generating means for generating an error signal Y j = y j - l o D j where l o D j represents an estimate of the value of the correctly equalized and filtered output sample y j , means for generating tap gain control inputs for adjusting the said adjustable tap gain means for each said sample x j in accordance with 0 ≅ E.sub.j {Y(j) x(j+ i)} where i= 0, 1, 2, . . . (2N- 1), and identifies the tap gain means (i) of the plurality (2N- 1) thereof. y(j) - y(j).]

Claim 9

Dependent Claim 281 words

An adjustable digital filter for use in a digital data transmission and receiving system for digitally filtering and equalizing a received data signal supplied to the filter as digital data samples x j at twice the baud rate of data transmission and including successive, alternating integer-baud and half-baud samples, comprising: means including a plurality of (2N- 1) successive delay stages for storing (2N- 1) successive ones of said digital data samples x j , a corresponding plurality of adjustable tap gain means respectively associated with said plurality of delay stages, each receiving the sample currently stored in the respectively associated delay stage and a corresponding tap gain control as inputs thereto, and producing as an output thereof the product of the inputs thereto, means for summing the outputs of said tap gain means and producing a filtered and equalized output sample y j in each baud interval for the corresponding integer-baud sample x j , means responsive to each sample y j for generating a corresponding, estimated value l o D j , means responsive to said summing means and also responsive to said estimated value generating means for generating an error signal Y j = y j - l o D j where l o D j represents an estimate of the value of the correctly equalized and filtered output sample y j , means for generating tap gain control inputs for adjusting the said adjustable tap gain means for each said sample x j in accordance with 0 ≅ E.sub.j {Y(j) x(j+ i)} where i= 0, 1, 2, . . . (2N- 1), and identifies the tap gain means (i) of the plurality (2N- 1) thereof. y(j) - y(j).]

Claim 10

Dependent Claim 140 words

An adjustable digital filter as recited in claim 7 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the integer baud sample storing delay stage respectively next adjacent each said half-integer baud sample storing delay stage in accordance with: g[(i+1/2)T].sub.t.sub.=KT ≃g(iT).sub.KT · [1+1/2+1/8]- g(iT).sub.(K.sub.-1)T · [1/2+1/4]+ g(iT).sub.(K.sub.-2)T · [1/8] where g[(i+1/2)T] identifies the tap gain setting for a given half-baud stage (i+1/2), i=1, 2, 3, . . . n, and g(iT) is the tap gain setting for the respective, preceding successively next adjacent integer baud stage (i) in a present and preceding baud intervals K, (K-1), and (K-2), respectively

Claim 11

Dependent Claim 174 words

An adjustable digital filter as recited in claim 7 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the integer baud sample storing delay stages respectively preceding and succeeding, and next adjacent each said half-integer baud sample storing delay stage in accordance with: g[(i+1/2)T].sub.t.sub.=KT ≈ 1/2{g(iT).sub.KT ·[1+1/2+1/8] + g[(i+1)T].sub.KT ·[1-1/2+1/8]-g(iT).sub.(K.sub.-1)T ·[1/2 + 1/4] + g[(i+1)T].sub.K.sub.-1)T · [1/2-1/4] +g(iT).sub.(K.sub.-2)T · [1/8] + g[(i+1)T].sub.(K.sub.-2)T ·[1/8]} where g[ (1+1/2)T] identifies the tap gain setting for a given half-baud stage (i+ 1/2), i=1, 2, 3, . . . n and g(iT) is the tap gain setting for the respective next adjacent, preceding integer baud stage (i) and g[ (i+1)T] is the tap gain setting for the respective, next adjacent, succeding integer baud stage (i+1) in a present and successively preceding baud intervals K, (K-1), and (K-2), respectively.

Claim 12

Dependent Claim 180 words

An adjustable digital filter as recited in claim 7 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the integer baud sample storing delay stages respectively preceding and succeeding, and next adjacent each said half-integer baud sample storing delay stage in accordance with: Δg[(i+1/2)T].sub.t.sub.=KT ≃1/2·{ g(iT).sub.KT · [1+1/2+1/8]+ Δg[(i+1)T].sub.KT ·[1-1/2+1/8] -Δg(iT).sub.(K-1)T · [1/2+1/4]+ Δg[(i+1)T] .sub.(K.sub.-1)T · [1/2 - 1/4]+ Δg(iT).sub. (K.sub.-2)T · [1/8] + Δ g[(i+1)T].sub.(K.sub.-2)T ·[1/8]} where g[ (1+1/2)T] identifies the tap gain setting for a given half-baud stage (i+ 1/2 ), i=1, 2, 3, . . . n and g(iT) is the tap gain setting for the respective, next adjacent, preceding integer baud stage (i) and g[(i+ 1)T] is the tap gain setting for the respective, next adjacent, succeeding integer baud stage (i+ 1) in a present and successively preceding baud intervals K, (K-1), and (K-2), respectively.

Claim 13

Dependent Claim 190 words

An adjustable digital filter as recited in claim 7 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the successive integer baud sample storing delay stages respectively next adjacent, preceding and succeeding, each said half-integer baud sample storing delay stage in accordance with: g[(i+1/2)T].sub.t.sub.=KT = 1/2· { g(iT).sub.KT ·[1+1/2+1/8] + g[(i+1)T].sub.KT · [1-1/2+1/8] -g(iT).sub.(K.sub.-1)T · [1/2+1/4]+ g[(i+1)T].sub.(K.sub.-1)T · [1/2- 1/4] + g(iT).sub.(K.sub.-2)T ·[1/8] + g[(i+1)T].sub.(K-2)T ·[1/8] - g(iT).sub.(K.sub.-3)T ·[1/48]+ g[(i+1)T].sub.(K.sub.-3)T · [1/48] + g(iT).sub.(K.sub.-4)T [1/384] + g[(i+1)T].sub.(K.sub.-4)T · [1/384] + . . . } where g[ (i+ 1/2 )T] identifies the tap gain setting for a given half-baud stage (i+ 1/2 ), i= 1, 2, 3, . . . n, g(iT), and g[ (i+ 1)T] are the tap gain settings for the respective, preceding and succeeding integer baud stages (i) and (i+ 1) in a present and successive, preceding baud intervals K, (K-1), and (K-2), . . . .

Claim 14

Dependent Claim 153 words

An adjustable digital filter as recited in claim 7 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the successive integer baud sample storing delay stages respectively next adjacent, preceding and succeeding, each said half-integer baud sample storing delay stage in accordance with: Δg[(i+1/2)T].sub.t=KT = 1/2 · {Δg(iT).sub.KT [13/8] +Δg[(i+1)T] .sub.KT · [5/8]} where Δ g[(i+ 1/2)T] identifies the tap gain setting adjustment for a given half-baud stage (i+ 1/2 ), i= 1, 2, 3, . . . n, and Δ g(iT), and Δ g[ (i+ 1)T] are the tap gain setting adjustments for the respective preceding and succeeding integer baud stages (i) and (i+ 1) in a current time interval K.

Claim 15

Dependent Claim 189 words

An adjustable digital filter as recited in claim 7 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the successive integer baud sample storing delay stages respectively next adjacent, preceding and succeeding, each said half-integer baud sample storing delay stage in accordance with: g[(i+1/2)T] 1/2· {g(iT)· [13/16] + g[(i+1)T]· [5/16] + g[(i-1)T]· [11/256]+ g[(i+2)T]· [4/256] + g[(i-2)T]· [9/4096] + g[(i+3)T]· [3/4096] +g[(i-3)T]· [7/65,536] +g[(i+4)T]· [2/65,536] + . . . } where g[ (i+1/2 )T] identifies the tap gain setting for a given half-baud stage (i+ 1/2 ), i= 1, 2, 3, . . . n, and g(iT), g(i- 1)T, . . . are the tap gain settings for the respective preceding integer baud stages (i), (i- 1), . . . and g[(i+ 1)T] , g[ i+2)T] , . . . are the tap gain settings for the respective, succeeding integer baud stages (i+1), (i+2), . . . .

Claim 16

Dependent Claim 54 words

An adjustable digital filter as recited in claim 7 wherein said adjusting means includes first means for adjusting the tap gain control inputs to each of the adjustable tap gain means associated with said delay stages storing integer-baud samples of said succession of samples in accordance with: E.sub.j {Y.sub.j · Sgn( x.sub.j.sub.+i)} = 0.

Claim 17

Dependent Claim 96 words

An adjustable digital filter as recited in claim 14 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the integer baud sample storing delay stage respectively next adjacent each said half-integer baud sample storing delay stage in accordance with: g[(i+1/2)T].sub.t.sub.=KT ≃g(iT).sub. KT · [1+ 1/2+1/8]- g(iT).sub. (K.sub.- 1)T · [1/2+1/4] + g(iT).sub. (K.sub.-2)T · [1/8].

Claim 18

Dependent Claim 181 words

An adjustable digital filter as recited in claim 14 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the integer baud sample storing delay stages respectively preceding and succeeding, and next adjacent each said half-integer baud sample storing delay stage in accordance with: g[(i+1/2)T].sub.t.sub.=KT ≈1/2{ g(iT).sub.KT · [1+1/2+1/8] + g[(i+1)T].sub.KT · [ 1-1/2+1/8] -g(iT).sub.(K.sub.-1)T · [1/2+1/4] + g[(i+1)T].sub.(K.sub.-1)T · [1/2-1/4] + g(iT).sub.(K.sub.-2)T · [1/8] + g[(i+1)T].sub.(K.sub.-2)T · [1/8]} where g[ (1+1/2)T] identifies the tap gain setting for a given half-baud stage (i+ 1/2 ), i= 1, 2, 3, . . . n and g(iT) is the tap gain setting for the respective next adjacent, preceding integer baud stage (i) and g[(i+ 1)T] is the tap gain setting for the respective, next adjacent, succeeding integer baud stage (i+i+1) in a present and successively preceding baud intervals K, (K-1), and (K-2), respectively.

Claim 19

Dependent Claim 184 words

An adjustable digital filter as recited in claim 14 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the integer baud samples storing delay stages respectively preceding and succeeding, and next adjacent each said half-integer baud sample storing delay stage in accordance with: Δg[(i+1/2)T].sub.t.sub.=KT ≃1/2 · { g(iT).sub.KT · [1+1/2+1/8]+ Δg[(i+1)T].sub.KT · [1-1/2+1/8] -Δg(iT).sub. (K.sub.-1)T · [1/2+1/4]+ Δg[(i+1)T].sub.(K.sub.-1)T · [1/2-1/4]+ Δg(iT).sub. (K.sub.-2)T · [1/8] + Δg[(i+1)T].sub.(K.sub.-2)T · [1/8]} where g[ (1+ 1/2)T] identifies the tap gain setting for a given half-baud stage (i+ 1/2 ), i= 1, 2, 3, . . . n and g(iT) is the tap gain setting for the respective next adjacent, preceding integer baud stage (i) and g[ (i+ 1)T] is the tap gain setting for the respective, next adjacent, succeeding integer baud stage (i+ 1) in a present and successively preceding baud intervals K, (K-1), and (K-2), respectively.

Claim 20

Dependent Claim 194 words

An adjustable digital filter as recited in claim 14 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the successive integer baud sample storing delay stages respectively next adjacent, preceding and succeeding, each said half-integer baud sample storing delay stage in accordance with: g[(i+1/2)T] .sub.t=KT =1/2·{ g(iT).sub.KT ·[ 1+1/2+1/8] +g[(i+1)T].sub.kT · [ 1-1/2+1/8] -g(iT).sub.(K-1)T · [1/2+1/4] + g[ [(i+ 1)T].sub.(K-1)T · [1/2· 1/4] + g(iT).sub.(K-2)T · [1/8] + g[(i+1)T].sub.(K-2)T · [1/8]- g(iT).sub.K-3)T · [1/48] + g[ (i+1) T].sub.(K-3)T · [1/48] + g(iT).sub.K-4)T [1/384] +g[ (i+1)T].sub.(K-4)T · 1/384] + . . . } where g[ (i+ 1/2 )T] identifies the tap gain setting for a given half-baud stage (i+ 1/2 ), i= 1, 2, 3, . . . n, g(iT), and g[(i+1)T] are the tap gain settings for the respective, preceding and succeeding integer baud stages (i) and (i+1) in a present and successive, preceding baud intervals K, (K-1), and (K-2), . . .

Claim 21

Dependent Claim 150 words

An adjustable digital filter as recited in claim 14 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the successive integer baud sample storing delay stages respectively next adjacent, preceding and succeeding, each said half-integer baud sample storing delay stage in accordance with: Δg[ (i+1/2)T].sub.t=kt = 1/2· Δg( iT).sub.kt [13/8] +Δg[ (i+1)T].sub.kt · [5/8]} where Δ g[ (i+ 1/2)T] identifies the tap gain setting adjustment for a given half-baud stage (i+1/2), i= 1, 2, 3, . . . n, and Δ g(iT), and Δg[ (i+1)T] are the tap gain setting adjustments for the respective preceding and succeeding integer baud stages (i) and (i+1) in a current time interval K.

Claim 22

Dependent Claim 195 words

An adjustable digital filter as recited in claim 14 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the successive integer baud sample storing delay stages respectively next adjacent, preceding and succeeding, each said half-integer baud sample storing delay stage in accordance with: g[ (i+1/2)T] = 1/2· { g(iT)·[13/16] + (g[(i+1)T]·[ 5/16] + g[ (i-1)T]·[11/256] + g[ (i+2)T]·[4/256] + g[ (i-2)T]·[9/4096] + g[ (i+3)T]·[ 3/4096] + g[ (i-3)T]·[7/65,536] + g[ (i+4)T]·[2/65,536] + . . . } where g[ (i+ 1/2)T] identifies the tap gain setting for a given half-baud stage (i+1/2), i= 1, 2, 3, . . . n, and g(iT), g(i- 1)T, . . . are the tap gain settings for the respective preceding integer baud stages (i), (i- 1), . . . and g[ (i+ 1)T] , g[i+2)T], , . . . are the tap gain settings for the respective, succeeding integer baud stages (i+ 1), (i+ 2), . . . .

Claim 23

Dependent Claim 57 words

An adjustable digital filter as recited in claim 7 wherein said adjusting means includes first means for adjusting the tap gain control inputs to each of the adjustable tap gain means associated with said delay stages storing integer-baud samples of said succession of samples in accordance with: Δg.sub.i = L· {Y.sub.j · sgn( x.sub.j.sub.+ i)}, L= constant.

Claim 24

Dependent Claim 92 words

An adjustable digital filter as recited in claim 21 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the integer baud sample storing delay stage respectively next adjacent each said half-integer baud sample storing delay stage in accordance with: g[(i+1/2)T].sub.t=KT ≃g(iT).sub. KT · [1+1/2+1/8]- g(iT).sub.(K-1)T ·[ 1/2+1/4] + g(iT).sub.K-2)T ·[ 1/8]

Claim 25

Dependent Claim 194 words

An adjustable digital filter as recited in claim 21 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the integer baud sample storing delay stages respectively preceding and succeeding, and next adjacent each said half-integer baud sample storing delay stage in accordance with: g[(i+1/2)T].sub.t=KT ≈ 1/2{ g (iT).sub.KT · [1+ 1/2 + 1/8] + g[ (i+1)T].sub.KT · [1-1/2 + 1/8] -g(iT).sub.(K-1)T ·[ 1/2 + 1/4] + g[ (i+1)T].sub.K-1)T ·[ 1/2 - 1/4] + g(iT).sub.K-2)T ·[.sup. 1/8] + g[ (i+1)T].sub.(K-2)T ·[ 1/8]} where g[ (1+1/2)T] identifies the tap gain setting for a given half-baud stage (i+ 1/2 ), i= 1, 2, 3, . . . n and g(iT) is the tap gain setting for the respective next adjacent, preceding integer baud stage (i) and g[(i+1)T] is the tap gain setting for the respective, next adjacent, succeeding integer baud stage (i+ 1) in a present and successively preceding baud intervals K, (K-1) and (K-2), respectively.

Claim 26

Dependent Claim 183 words

An adjustable digital filter as recited in claim 21 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the integer baud sample storing delay stages respectively preceding and succeeding, and next adjacent each said half-integer baud sample storing delay stage in accordance with: Δg[(i+1/2)T].sub.t=KT ≈1/2·} g(iT).sub.KT · [1+1/2+1/8]+ Δg[(i+1)T].sub.KT · [1-1/2+1/8] -Δg(iT).sub. (K-1)T · [1/2+1/4] + Δ g[(i+1)T] .sub.(K-1)T ·[ 1/2-1/4]+Δg(iT).sub.(K-2)T ·.sup.. [1/8] + Δg [(i+1)T].sub.(K-2)T ·[1/8]} where g[ (1+1/2)Tπ identifies the tap gain setting for a given half-baud stage (i+ 1/2 ), i= 1, 2, 3 , . . . n and g(iT) is the tap gain setting for the respective next adjacent, preceding integer baud stage (i) and g[ (i+ 1)T] is the tap gain setting for the respective, next adjacent, succeeding integer baud stage (i+ 1) in a present and successively preceding baud intervals K, (K-1), and (K-2), respectively.

Claim 27

Dependent Claim 155 words

An adjustable digital filter as recited in claim 21 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the successive integer baud sample storing delay stages respectively next adjacent, preceding and succeeding, each said half-integer baud sample storing delay stage in accordance with: Δg[ (i+ 1/2)T].sub.t.sub.=KT = 1/2· {Δ g( iT).sub.KT [13/8] +Δg[(i+1)T].sub.KT · [5/8]} where Δ g[ (i+ 1/2 )T] identifies the tap gain setting adjustment for a given half-baud stage (i+ 1/2 ), i= 1, 2, 3, . . . n, and Δ g(iT), and Δ g[(i+ 1)T] are the tap gain setting adjustments for the respective preceding and succeeding integer baud stages (i) and (i+1) in a current time interval K.

Claim 28

Dependent Claim 54 words

An adjustable digital filter as recited in claim 7 wherein said adjusting means includes first means for adjusting the tap gain control inputs to each of the adjustable tap gain means associated with said delay stages storing integer-baud samples of said succession of samples in accordance with: Δg.sub.i = K· {sgn(y.sub.j)· sgn(x.sub.j.sub.+i)}, K= constant

Claim 29

Dependent Claim 93 words

An adjustable digital filter as recited in claim 26 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the integer baud sample storing delay stage respectively next adjacent each said half-integer baud sample storing delay stage in accordance with: g[(i+1/2)T] .sub.t.sub.=KT ≃g(iT).sub.KT · [1+1/2+1/8]- g(iT).sub. (K.sub.-1)T · [1/2+1/4]+ g(iT).sub. (K.sub.-2)T · [1/8].

Claim 30

Dependent Claim 176 words

An adjustable digital filter as recited in claim 26 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the integer baud sample storing delay stages respectively preceding and succeeding, and next adjacent each said half-integer baud sample storing delay stage in accordance with: g[(i+1/2)T] .sub.t.sub.=KT ≈1/2{g(iT).sub.KT ·[1+1/2+1/8] + g[(i+1)T].sub.KT ·[1-1/2+1/8] -g(iT).sub.(K-1)T ·[1/2+1/4] + g[(i+1)T].sub.(K-1)T ·[1/2-1/4] + g(iT).sub.(K-2)T ·[1/8 ] + g[(i+1)T].sub.(K-2)T ·[1/8]} where g[ (1+1/2)T] identifies the tap gain setting for a given half-baud stage (i+ 1/2 ), i= 1, 2, 3, . . . n and g(iT) is the tap gain setting for the respective next adjacent, preceding integer baud stage (i) and g[ (i+ 1)T] is the tap gain setting for the respective, next adjacent, succeeding integer baud stage (i+1) in a present and successively preceding baud intervals K, (K-1), and (K-2), respectively.

Claim 31

Dependent Claim 181 words

An adjustable digital filter as recited in claim 26 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-integer baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the integer baud sample storing delay stages respectively preceding and succeeding, and next adjacent each said half-integer baud sample storing delay stage in accordance with: Δg[(i+1/2)T].sub.t.sub.=KT ≃1/2· { g(iT).sub.KT · [1+1/2+1/8]+ Δg[(i+1)T].sub.KT ·[1-1/2+1/8] -Δg(iT).sub. (K.sub.-1)T · [1/2+1/4]+ Δg[(i+1)T].sub.(K.sub.-1)T · [1/2-1/4]+ Δ g(iT).sub. (K.sub.-2)T · [1/8] + Δg[(i+1)T].sub.(K.sub.-2)T ·[1/8]} where g[ (1+1/2)T] identifies the tap gain setting for a given half-baud stage (i+ 1/2 ), i= 1, 2, 3, . . . n and g(iT) is the tap gain setting for the respective next adjacent, preceding integer baud stage (i) and g[ (i+ 1)T] is the tap gain setting for the respective, next adjacent, succeeding integer baud stage (i+ 1) in a present and successively preceding baud intervals K, (K-1), and (K-2), respectively.

Claim 32

Dependent Claim 155 words

An adjustable digital filter as recited in claim 26 wherein said adjusting means further includes second means for adjusting said adjustable tap gain means associated with each said delay stage storing half-interger baud samples as a function of the adjustment by said first adjusting means of the tap gain control inputs to the adjustable tap gain means associated with the successive integer baud sample storing delay stages respectively next adjacent, preceding and succeeding, each said half-integer baud sample storing delay stage in accordance with: Δ g[(i+1/2)T].sub.t.sub.=KT = 1/2· {Δg(iT).sub. kT [13/8] +Δ g[(i+1)T].sub.KT · [5/8]} where Δ g[ (i+ 1/2)T] identifies the tap gain setting adjustment for a given half-baud stage (i+ 1/2 ), i= 1, 2, 3, . . . n, and Δ g(iT), and Δ g[ (i+ 1)T] are the tap gain setting adjustments for the respective preceding and succeeding integer baud stages (i) and (i+ 1) in a current time interval K.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1980-06-27	1980-12-27	1981-06-28	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1984-06-27	1984-12-27	1985-06-28	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1988-06-27	1988-12-27	1989-06-28	$7700.00	Window Closed / Lapsed

Adjustable digital filter for high speed digital transmission

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