US3716807A
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US
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Recursive automatic equalizer and method of operation therefore
Assignee: International Business Machines Corp
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Filing: 1971-05-24
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Granted: 1973-02-13
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Expires: 1991-05-24
Abstract
Abstract A recursive automatic equalizer with extremely fast convergence is disclosed. The equalizer includes a plurality of equalizer stages connected in cascade which first reduces impulse response of the communication channel to substantially zero. The front portion or sidelobe is reduced to substantially zero distortion by adjusting the tap settings of successive equalizer stages after successive iterations (the first iteration adjusts the tap settings of the first equalizer stage, the second iteration adjusts the tap settings of the second equalizer stage, and so on) such that after n iterations a given initial distortion D is reduced to substantially zero. The tap setting algorithm involved and the method of operating the cascaded equalizer is disclosed. Finally, after n iterations, the output signal which can be described by the function 1-A(n) is modified by the reciprocal of the foregoing function and, is this manner, the rear or trailing portion of an input signal which is to be equalized has its rear sidelobe distortion reduced to substantially zero leaving only the desired main pulse. Apparatus for modifying the trailing or rear end of a pulse to be equalized is also disclosed.
Inventors
- 👤 R Sha
- 👤 D Tang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:43
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L25/03012; H04L25/03114; H04L25/03133
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
217 words
A method for equalizing an electrical signal comprising the steps of: applying for m iteration an electrical Signal sequence represented by the function 1-A(0) to the input of an equalizer arrangement having a plurality of adjustable tap settings; equalizing only the front portion of said signal to provide for m iterations an output signal represented by the function 1A(m) where m 1, 2, 3, . . . , n, 1-A(m) 1-Af(m) - Ar(m), 1A(n) congruent 1-Ar(n) 1-A(0) Lambda (0) Alpha N(0)zN +. . .+ Alpha 1(0)z1 + 0(0) + Alpha 1(0)z 1 + . . . + Alpha N(0)z N and is the output of a transmission medium in response to a unit pulse input decomposed as the main pulse and side lobes, Alpha is the amplitude value of a signal at a sampling instant and the subscripts associated with the term Alpha are the numbers of the sampling instants before and after the main pulse, Af(m) and Ar(m) are the contributions to the signal distortion of the front and rear side lobes, respectively, and modifying after the nth iteration said output signal represented by the function 1-A(n) by its reciprocal in a recursive equalizer stage having a plurality of adjustable tap settings to reduce the rear end distortion of said signal to a value approaching zero.
Claim 2
Independent Claim
217 words
A method for equalizing an electrical signal comprising the steps of: applying for m iteration an electrical Signal sequence represented by the function 1-A(0) to the input of an equalizer arrangement having a plurality of adjustable tap settings; equalizing only the front portion of said signal to provide for m iterations an output signal represented by the function 1A(m) where m 1, 2, 3, . . . , n, 1-A(m) 1-Af(m) - Ar(m), 1A(n) congruent 1-Ar(n) 1-A(0) Lambda (0) Alpha N(0)zN +. . .+ Alpha 1(0)z1 + 0(0) + Alpha 1(0)z 1 + . . . + Alpha N(0)z N and is the output of a transmission medium in response to a unit pulse input decomposed as the main pulse and side lobes, Alpha is the amplitude value of a signal at a sampling instant and the subscripts associated with the term Alpha are the numbers of the sampling instants before and after the main pulse, Af(m) and Ar(m) are the contributions to the signal distortion of the front and rear side lobes, respectively, and modifying after the nth iteration said output signal represented by the function 1-A(n) by its reciprocal in a recursive equalizer stage having a plurality of adjustable tap settings to reduce the rear end distortion of said signal to a value approaching zero.
Claim 3
Independent Claim
217 words
A method for equalizing an electrical signal comprising the steps of: applying for m iteration an electrical Signal sequence represented by the function 1-A(0) to the input of an equalizer arrangement having a plurality of adjustable tap settings; equalizing only the front portion of said signal to provide for m iterations an output signal represented by the function 1-A(m) where m 1, 2, 3, . . . , n, 1-A(m) 1-Af(m) - Ar(m), 1-A(n) Congruent 1-Ar(n) 1-A(0) Lambda (0) Alpha N(0)zN +. . .+ Alpha 1(0)z1 + 0(0) + Alpha 1(0)z 1 + . . . + Alpha N(0)z N and is the output of a transmission medium in response to a unit pulse input decomposed as the main pulse and side lobes, Alpha is the amplitude value of a signal at a sampling instant and the subscripts associated with the term Alpha are the numbers of the sampling instants before and after the main pulse, Af(m) and Ar(m) are the contributions to the signal distortion of the front and rear side lobes, respectively, and modifying after the nth iteration said output signal represented by the function 1-A(n) by its reciprocal in a recursive equalizer stage having a plurality of adjustable tap settings to reduce the rear end distortion of said signal to a value approaching zero.
Claim 4
Independent Claim
217 words
A method for equalizing an electrical signal comprising the steps of: applying for m iteration an electrical Signal sequence represented by the function 1-A(0) to the input of an equalizer arrangement having a plurality of adjustable tap settings; equalizing only the front portion of said signal to provide for m iterations an output signal represented by the function 1-A(m) where m 1, 2, 3, . . . , n, 1-A(m) 1-Af(m) - Ar(m), 1-A(n) Congruent 1-Ar(n) 1-A(0) Lambda (0) Alpha N(0)zN +. . .+ Alpha 1(0)z1 + 0(0) + Alpha 1(0)z 1 + . . . + Alpha N(0)z N and is the output of a transmission medium in response to a unit pulse input decomposed as the main pulse and side lobes, Alpha is the amplitude value of a signal at a sampling instant and the subscripts associated with the term Alpha are the numbers of the sampling instants before and after the main pulse, Af(m) and Ar(m) are the contributions to the signal distortion of the front and rear side lobes, respectively, and modifying after the nth iteration said output signal represented by the function 1-A(n) by its reciprocal in a recursive equalizer stage having a plurality of adjustable tap settings to reduce the rear end distortion of said signal to a value approaching zero.
Claim 5
Dependent Claim
35 words
A method according to claim 1 further including the step of applying said electrical signal to a signal averaging circuit to generate an output signal which is the average of a number of input signals.
Claim 6
Dependent Claim
45 words
A method according to claim 1 wherein the step of equalizing said signal includes the step of: adjusting initially said plurality of tap settings to zero with the exception of the tap settings which correspond to the main pulse, the latter being adjusted to unity.
Claim 7
Dependent Claim
86 words
A method according to claim 1 wherein the step of equalizing said signal includes the steps of: passing said electrical signal through m equalizer stages, modifying said output signal in a summing circuit to provide a modified signal represented by the function 1+A(m 1) where 1+A(m 1) 1+Af(m 1) +Ar(m 1), feeding the front end portion of said last mentioned signal (1+Af(m 1) ) to a tap adjusting means, and, modifying the tap settings of the mth equalizer stage in accordance with the function 1+Af(m 1).
Claim 8
Dependent Claim
33 words
A method according to claim 1 further including the step of: normalizing the function 1-A(0) at the beginning of each iteration to normalize the main pulse of the electrical signal sequence to unity.
Claim 9
Dependent Claim
147 words
A method according to claim 1 wherein the step of modifying the signal represented by the function 1-A(n) includes the steps of: applying said signal to a summing circuit during the nth iteration which provides at its output the negative of the contribution of the rear sidelobe at the sampling instants represented by the function Ar(n), feeding the signal represented by said last mentioned function to a tap adjusting means, modifying the tap settings of said recursive stage in accordance with the function Ar(n), applying during the interval after the nth iteration, said output signal represented by the function 1-A(n) to said recursive equalizer stage, sensing the main pulse associated with said output signal, and, feeding back to said recursive equalizer stage the signal represented by the function Ar(n) to cancel out the contributions of the rear sidelobes at the sampling instantS represented by the function -Ar(n).
Claim 10
Independent Claim
229 words
A method for equalizing an electrical signal sequence represented by the function 1-A(0) comprising the steps of: applying said electrical signal for m iterations to the input of m equalizer stages each of which have adjustable tap settings; modifying said electrical signal by adjusting said tap settings of the mth equalizer in accordance with the function 1+Af(m 1) to produce successive outputs at each of said stages for successive iterations as represented by the function 1-A(m) where m 1, 2, 3, . . . , n, 1-A(m) 1-Af(m)-Ar(m), 1-A(0) Lambda (0) Alpha N(0)zN + . . . + Alpha 1(o)z1 + Alpha 0(0) + Alpha 1(0)z 1 + . . . + Alpha N(0)z N and is the output of a transmission medium in response to a unit pulse input decomposed as the main pulse and side lobes, Alpha is the amplitude value of a signal at a sampling instant and the subscripts associated with the term Alpha are the numbers of the sampling instants before and after the main pulse, Af(m) and Ar(m) are the contributions to the signal distortion of the front and rear side lobes, respectively, and modifying after the nth iteration the function 1-A(n) Congruent 1-Ar(n) by its reciprocal in a recursive equalizer stage having a plurality of adjustable tap settings to reduce the rear end distortion of said signal to a value approaching zero.
Claim 11
Independent Claim
229 words
A method for equalizing an electrical signal sequence represented by the function 1-A(0) comprising the steps of: applying said electrical signal for m iterations to the input of m equalizer stages each of which have adjustable tap settings; modifying said electrical signal by adjusting said tap settings of the mth equalizer in accordance with the function 1+Af(m 1) to produce successive outputs at each of said stages for successive iterations as represented by the function 1-A(m) where m 1, 2, 3, . . . , n, 1-A(m) 1-Af(m)-Ar(m), 1-A(0) Lambda (0) Alpha N(0)zN + . . . + Alpha 1(o)z1 + Alpha 0(0) + Alpha 1(0)z 1 + . . . + Alpha N(0)z N and is the output of a transmission medium in response to a unit pulse input decomposed as the main pulse and side lobes, Alpha is the amplitude value of a signal at a sampling instant and the subscripts associated with the term Alpha are the numbers of the sampling instants before and after the main pulse, Af(m) and Ar(m) are the contributions to the signal distortion of the front and rear side lobes, respectively, and modifying after the nth iteration the function 1-A(n) Congruent 1-Ar(n) by its reciprocal in a recursive equalizer stage having a plurality of adjustable tap settings to reduce the rear end distortion of said signal to a value approaching zero.
Claim 12
Dependent Claim
92 words
A method according to claim 7 wherein the step of modifying said electrical signal includes the steps of: applying said output signal after each iteration to a summing circuit to change said signal to a signal represented by the function 1+A(m 1) where 1+A(m 1) 1+Af(m 1)+Ar(m 1), determining the value of the last mentioned function for each sampling point relating to the front portion only (1+Af(m 1)) of said electrical signal sequence, and, adjusting said adjustable tap settings on the mth of said equalizer stages according to the previously determined value.
Claim 13
Dependent Claim
33 words
A method according to claim 7 further including the step of: normalizing the function 1-A(0) at the beginning of each iteration to normalize the main pulse of said electrical signal sequence to unity.
Claim 14
Dependent Claim
43 words
A method according to claim 7 further including the step of: adjusting initially the tap settings of said equalizer stages to zero with the exception of tap settings which correspond to the main pulse of said sequence the latter being adjusted to unity.
Claim 15
Dependent Claim
150 words
A method according to claim 7 wherein the step of modifying the signal represented by the function 1-A(n) by its reciprocal includes the steps of: applying said signal to a summing circuit during the nth iteration which provides at its output the negative of the contribution of the rear sidelobes at the sampling instants represented by the function Ar(n), feeding the signal represented by said last mentioned function to a tap adjusting means, modifying the tap settings of said recursive stage in accordance with the function Ar(n), applying during the interval after the nth iteration, said output signal represented by the function 1-A(n) to said recursive equalizer stage, sensing the main pulse associated with said output signal, and, feeding back to said recursive equalizer stage the signal represented by the function Ar(n) to cancel out the contributions of the rear sidelobes at the sampling instants represented by the function -Ar(n).
Claim 16
Dependent Claim
224 words
Apparatus for equalizing an electrical signal comprising: a signal source for producing an electrical signal; a communications medium connected to said signal source which introduces distortion on said electrical signal to provide a distorted electrical signal represented by the function 1-A(0) and, means connected to said communications medium for equalized the front portion only of said distorted electrical signal to provide at the output thereof an output signal represented by the function 1-A(m) for m iterations where m 1, 2, 3, . . . , n, wherein 1-A(m) 1-Af(m)-Ar(m), 1-A(n) Congruent 1-Ar(n) 1-A(0) Lambda (0) Alpha N(0)zN +. . . + Alpha 1(0)z1 + Alpha 0(0) + Alpha 1(0)z 1 +. . . + Alpha N(0)z N and is the output of a transmission medium in response to a unit pulse input decomposed as the main pulse and side lobes, Alpha is the amplitude value of a signal at sampling instant and the subscripts associated with the term Alpha are the numbers of the sampling instants before and after the main pulse, Af(m) and Ar(m) are the contributions to the signal distortion of the front and rear side lobes, respectively, and means operable after the nth iteration for modifying the function 1-A(n) by its reciprocal connected to said equalizing means to reduce the rear end distortion of said signal to a value approaching zero.
Claim 17
Dependent Claim
224 words
Apparatus for equalizing an electrical signal comprising: a signal source for producing an electrical signal; a communications medium connected to said signal source which introduces distortion on said electrical signal to provide a distorted electrical signal represented by the function 1-A(0) and, means connected to said communications medium for equalized the front portion only of said distorted electrical signal to provide at the output thereof an output signal represented by the function 1-A(m) for m iterations where m 1, 2, 3, . . . , n, wherein 1-A(m) 1-Af(m)-Ar(m), 1-A(n) Congruent 1-Ar(n) 1-A(0) Lambda (0) Alpha N(0)zN +. . . + Alpha 1(0)z1 + Alpha 0(0) + Alpha 1(0)z 1 +. . . + Alpha N(0)z N and is the output of a transmission medium in response to a unit pulse input decomposed as the main pulse and side lobes, Alpha is the amplitude value of a signal at sampling instant and the subscripts associated with the term Alpha are the numbers of the sampling instants before and after the main pulse, Af(m) and Ar(m) are the contributions to the signal distortion of the front and rear side lobes, respectively, and means operable after the nth iteration for modifying the function 1-A(n) by its reciprocal connected to said equalizing means to reduce the rear end distortion of said signal to a value approaching zero.
Claim 18
Dependent Claim
38 words
Apparatus according to claim 12 further including means interposed between said communications medium and said equalizing means for averaging said distorted electrical signal to generate an output signal which is the average of a plurality of input signals.
Claim 19
Dependent Claim
207 words
Apparatus according to claim 12 wherein said means for modifying the function 1-A(n) by its reciprocal includes: means for converting said signal during the nth interation to provide at the output thereof the negative of the contributions of the rear sidelobe at the sampling instants as represented by the function Ar(n) connected to the output of said equalizing means, tap adjusting means responsive to the output of said converting means for providing tap setting outputs which are proportional to the function Ar(n) at the sampling instants, a plurality of multipliers, a plurality of adjustable tap settings on said multipliers connected to said tap setting means responsive to said tap setting outputs which are adjusted during said nth iteration, a plurality of summing circuits and delay devices arranged in an interleaving series manner connected to the output of said equalizer means during the interval succeeding the nth iteration each of said summing circuits being connected to a different associated multiplier, threshold means responsive to the main pulse of said electrical signal operative in the interval after said nth iteration for providing an output via said multipliers to said summing circuits which cancels the contribution of the rear sidelobe at the sampling instants as represented by the function -Ar(n).
Claim 20
Dependent Claim
99 words
Apparatus according to claim 12 wherein said means for equalizing said distorted electrical signal includes a plurality of equalizer stages each having a plurality of adjustable tap settings the output of one stage being connected to the input of a succeeding stage, means connected to the last of said equalizer stages for modifying said output signal to provide the function 1+A(m 1) wherein 1+A(m 1) 1+Af(m 1) + Ar(m 1) and, means connected to said modifying means and said adjustable tap settings for adjusting the tap settings associated with mth equalizer stage in accordance with the function 1+Af(m 1).
Claim 21
Dependent Claim
26 words
Apparatus according to claim 15 wherein said means for modifying said output signal includes a summer circuit which converts the function 1-A(m 1) to 1+A(m 1).
Claim 22
Dependent Claim
30 words
Apparatus according to claim 15 wherein said means for adjusting includes drive means connected to said adjustable tap settings responsive to the signal sequence represented by the function 1+Af(m 1).
Claim 23
Dependent Claim
15 words
Apparatus according to claim 15 wherein each said equalizer stage includes a tapped delay line.
Claim 24
Dependent Claim
14 words
Apparatus according to claim 15 wherein each said equalizer stage includes a shift register.
Claim 25
Dependent Claim
249 words
Apparatus for equalizing an electrical signal represented by the function 1-A(0) comprising: means for applying said electrical signal for m iterations to the input of m equalizer stages each of which have a plurality of adjustable tap settings, the output of one stage being connected to the input of a succeeding stage, and means connected to the last of said plurality of equalizers and said plurality of adjustable tap settings for modifying said tap settings to produce successive outputs at the mth of said equalizer stages for successive iterations as represented by the function 1-A(m) where m 1, 2, 3, . . . , n, 1-A(m) 1-Af(m)-Ar(m), 1-A(0) Lambda (0) Alpha N (0) zN + . . . + Alpha 1(0) z1 + Alpha 0(0) + Alpha 1(0)z 1 + . . . + Alpha N(0) z N and is the output of a transmission medium in response to a unit pulse input decomposed as the main pulse and side lobes, Alpha is the amplitude value of a signal at a sampling instant and the subscripts associated with the term Alpha are the numbers of the sampling instants before and after the main pulse, Af(m) and Ar(m) are the contributions to the signal distortion of the front and rear sidelobes, respectively, and means operable after the nth iteration for modifying the function 1-A(n) Congruent 1-Ar(n) by its reciprocal connected to the last of said equalizer stages to reduce the total distortion of said signal to a value approaching zero.
Claim 26
Dependent Claim
249 words
Apparatus for equalizing an electrical signal represented by the function 1-A(0) comprising: means for applying said electrical signal for m iterations to the input of m equalizer stages each of which have a plurality of adjustable tap settings, the output of one stage being connected to the input of a succeeding stage, and means connected to the last of said plurality of equalizers and said plurality of adjustable tap settings for modifying said tap settings to produce successive outputs at the mth of said equalizer stages for successive iterations as represented by the function 1-A(m) where m 1, 2, 3, . . . , n, 1-A(m) 1-Af(m)-Ar(m), 1-A(0) Lambda (0) Alpha N (0) zN + . . . + Alpha 1(0) z1 + Alpha 0(0) + Alpha 1(0)z 1 + . . . + Alpha N(0) z N and is the output of a transmission medium in response to a unit pulse input decomposed as the main pulse and side lobes, Alpha is the amplitude value of a signal at a sampling instant and the subscripts associated with the term Alpha are the numbers of the sampling instants before and after the main pulse, Af(m) and Ar(m) are the contributions to the signal distortion of the front and rear sidelobes, respectively, and means operable after the nth iteration for modifying the function 1-A(n) Congruent 1-Ar(n) by its reciprocal connected to the last of said equalizer stages to reduce the total distortion of said signal to a value approaching zero.
Claim 27
Dependent Claim
207 words
Apparatus according to claim 20 wherein said means for modifying the function 1-A(n) by it reciprocal includes: means for converting said signal during the nth iteration to provide at the output thereof the negative of the contributions of the rear sidelobe at the sampling instants as represented by the function Ar(n) connected to the output of said equalizing means, tap adjusting means responsive to the output of said converting means for providing tap setting outputs which are proportional to the function Ar(n) at the sampling instants, a plurality of multipliers, a plurality of adjustable tap settings on said multipliers connected to said tap setting means responsive to said tap setting outputs which are adjusted during said nth iteration, a plurality of summing circuits and delay devices arranged in an interleaving series manner connected to the output of said equalizer means during the interval succeeding the nth iteration each of said summing circuits being connected to a different associated multiplier, threshold means Responsive to the main pulse of said electrical signal operative in the interval after said nth iteration for providing an output via said multipliers to said summing circuits which cancels the contribution of the rear sidelobe at the sampling instants as represented by the function -Ar(n).
Claim 28
Dependent Claim
41 words
Apparatus according to claim 20 wherein said means for modifying includes a summer circuit which converts the output of the mth stage to a signal as represented by the function 1-A(m 1) to 1+A(m-1), where 1+A(m 1) 1+Af(m 1) +Ar(m 1).
Claim 29
Dependent Claim
57 words
Apparatus according to claim 22 further including tap adjusting means connected to said summer and each of said equalizer stages for converting that portion of the output electrical signal of said summer circuit represented by the function 1+Af(m 1) to mechanical motion and linkages connected between said tap adjusting means and said plurality of adjustable tap settings.
Claim 30
Dependent Claim
233 words
Apparatus for equalizing an electrical signal sequence represented by the function 1-A(0) comprising: means for applying said electrical signal for m iterations to the input of m cascaded equalizer stages each of which have a plurality of adjustable tap settings the output of one stage being connected to the input of a succeeding stage; and means for modifying said electrical signal sequence by adjusting said tap settings in accordance with the function 1+Af(m 1) to produce successive outputs at each of said equalizer stages for successive iterations as represented by the function 1-A(m) where m 1, 2, 3,...,n, 1-A(m) 1-Af(m)-Ar(m) 1-A(0) Lambda (0) Alpha N(0)zN +...+ Alpha 1(0)z1 + Alpha 0(0) + Alpha 1(0)z 1 +...+ Alpha N(0)z N and is the output of a transmission medium in response to a unit pulse input decomposed as the main pulse and side lobes, Alpha is the amplitude value of a signal at a sampling instant and the subscripts associated with the term Alpha are the numbers of the sampling instants before and after the main pulse, Af(m) and Ar(m) are the contributions to the signal distortion of the front and rear side lobes, respectively, and means operable after the nth iteration for modifying the function 1-A(n) > or = 1-Ar(n) by its reciprocal connected to the last of said equalizer stages to reduce the total distortion of said signal to a value approaching zero.
Claim 31
Dependent Claim
233 words
Apparatus for equalizing an electrical signal sequence represented by the function 1-A(0) comprising: means for applying said electrical signal for m iterations to the input of m cascaded equalizer stages each of which have a plurality of adjustable tap settings the output of one stage being connected to the input of a succeeding stage; and means for modifying said electrical signal sequence by adjusting said tap settings in accordance with the function 1+Af(m 1) to produce successive outputs at each of said equalizer stages for successive iterations as represented by the function 1-A(m) where m 1, 2, 3,...,n, 1-A(m) 1-Af(m)-Ar(m) 1-A(0) Lambda (0) Alpha N(0)zN +...+ Alpha 1(0)z1 + Alpha 0(0) + Alpha 1(0)z 1 +...+ Alpha N(0)z N and is the output of a transmission medium in response to a unit pulse input decomposed as the main pulse and side lobes, Alpha is the amplitude value of a signal at a sampling instant and the subscripts associated with the term Alpha are the numbers of the sampling instants before and after the main pulse, Af(m) and Ar(m) are the contributions to the signal distortion of the front and rear side lobes, respectively, and means operable after the nth iteration for modifying the function 1-A(n) > or = 1-Ar(n) by its reciprocal connected to the last of said equalizer stages to reduce the total distortion of said signal to a value approaching zero.
Claim 32
Dependent Claim
98 words
Apparatus according to claim 24 wherein said means for modifying includes a summing circuit connected to the last of said plurality of equalizer stages to change said signal to a signal represented by the function 1+A(m 1) wherein 1+A(m 1) +Ar(m 1), means connected to said summer circuit for determining the value of that portion of said last mentioned function for a plurality of sampling points of said electrical signal sequence represented by the function 1+Af(m 1) , and means for adjusting each of said plurality of tap settings on the mth of said plurality of equalizer stages.
References Cited (Backward Citations)
US3624562A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-13 | 1976-08-14 | 1977-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-13 | 1980-08-14 | 1981-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-13 | 1984-08-14 | 1985-02-13 | $7700.00 | Window Closed / Lapsed |