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EP0316459A1
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Fast timing acquisition for partial-response signalling
Assignee: International Business Machines Corp
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Filing: 1987-11-13
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Granted: —
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Expires: 2007-11-13
Abstract
Abstract An apparatus and a method for fast acquisition of the sample-timing phase in systems using partial-response signalling are disclosed. For fast initial adjustment of the timing phase, a known preamble is transmitted. During that phase, previous schemes could occasionally hang up for an extended period of time at the unstable equilibrium point halfway between the desired sampling times. The new procedure eliminates the hangup problem by introducing a hysteresis effect which greatly diminshes the probability of reversals in the once chosen direction of timing-phase adjustment. Thus, reliable adjustment of the timing phase with a much shorter preamble is achieved. The apparatus for furnishing a timing correction signal Δτ n includes a timing gradient generator portion (41) and a data sample reconstruction portion (43). The data sample reconstruction portion (43) develops a present reconstructed data sample x̂ n from the present received signal sample y n and a previous reconstructed data sample. The output x̂ n of the data sample reconstruction portion is delayed and furnished to the gradient generation portion (41) which also receives the present received signal sample y n and a delayed received signal sample, for generating the timing correction signal Δτ n .
Inventors
- 👤 François Bernard Dolivo
- 👤 Gottfried Ungerboeck
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 14:03
CPC Classifications
H; H04; H04L; H04L7/00; H04L7/0054; H04L7/0062; G; G11; G11B; G11B20/00; G11B20/10; G11B20/10009; G11B20/10046; G11B20/10055; G11B20/14; G11B20/1403; H04L25/00; H04L25/38; H04L25/40; H04L25/49; H04L25/4917; H04L25/4919; H04L25/497; H04L7/04; H04L7/10; H04L7/041; H04L7/046
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
235 words
In a receiver for data having been sent or recorded as partial-response (PR) signals, apparatus for generating a timing gradient value Δτ n for initially acquiring the sampling phase when a signal resulting from the transmission of a known preamble of the form + 1 + 1-1-1 + 1 + 1 ... is received, said apparatus comprising: - a common input (55) for received signal samples y n of a transmitted or recorded PR signal; - first delay means (67) having at least one delay stage, for accepting the present received signal sample y n and for providing at least one previous received signal sample y n-i ; - second delay means (61) having at least two delay stages, for accepting a present reconstructed data sample x̂ n and for providing at least a first previous reconstructed data sample x̂ n-j ; - reconstruction means (43) connected to said common input and to said second delay means for generating said present reconstructed data sample x̂ n in response to said present received signal sample y n and at least said first previous reconstructed data sample x̂ n-j ; and - timing gradient generation means (41) connected to said common input and to said first and second delay means and being responsive to said present received signal sample and to output values of said two delay means, for generating said timing gradient value Δτ n .
Claim 2
Dependent Claim
235 words
In a receiver for data having been sent or recorded as partial-response (PR) signals, apparatus for generating a timing gradient value Δτ n for initially acquiring the sampling phase when a signal resulting from the transmission of a known preamble of the form + 1 + 1-1-1 + 1 + 1 ... is received, said apparatus comprising: - a common input (55) for received signal samples y n of a transmitted or recorded PR signal; - first delay means (67) having at least one delay stage, for accepting the present received signal sample y n and for providing at least one previous received signal sample y n-i ; - second delay means (61) having at least two delay stages, for accepting a present reconstructed data sample x̂ n and for providing at least a first previous reconstructed data sample x̂ n-j ; - reconstruction means (43) connected to said common input and to said second delay means for generating said present reconstructed data sample x̂ n in response to said present received signal sample y n and at least said first previous reconstructed data sample x̂ n-j ; and - timing gradient generation means (41) connected to said common input and to said first and second delay means and being responsive to said present received signal sample and to output values of said two delay means, for generating said timing gradient value Δτ n .
Claim 3
Dependent Claim
161 words
Apparatus in accordance with claim 1, characterized in that said reconstruction means (43) comprises: - first non-linear conversion means (51) connected to said second delay means (61) for receiving said first previous reconstructed data sample x̂ n-j , and furnishing on its output (65) one of two possible given values (+ e , - e) as threshold ηn in response to the sign of said first previous reconstructed data sample x̂ n-j ; and - second non-linear conversion means (53) having a first input connected to the output (65) of said first non-linear conversion means for receiving said threshold ηn, and a second input connected to said common input (55) for receiving a present received signal sample y n , and furnishing on its output (59) one of two possible data amplitude values (+ 2 , - 2) as reconstructed data sample x n in response to the difference between said present received signal sample y n and said threshold ηn.
Claim 4
Dependent Claim
123 words
Apparatus in accordance with claim 1 or claim 2, characterized in that - said first delay means (67) comprises only one delay stage having a delay of one sampling period, and provides at its output a delayed received signal sample y n-1 , which constitutes said previous received signal sample y n-1 , and - said second delay means (61) comprises two delay stages (61(1), 61(2)) in series, the first (61(1)) of said delay stages providing at its output a delayed reconstructed data sample x̂ n-1 as a second previous reconstructed data sample, and the second (61(2)) of said delay stages providing at its output another delayed reconstructed data sample x̂ n-2 which constitutes said first previous reconstructed data sample x̂ n-j .
Claim 5
Dependent Claim
174 words
Apparatus in accordance with claim 3, characterized in that said timing gradient generation means (41) comprises: - first multiplying means (45) having one input connected to said common input (55) for receiving said present received signal sample y n , another input connected to an output of said second delay means (61) for receiving said second previous reconstructed data sample x̂ n-1 , and having an output; - second multiplying means (47) having one input connected to the output (59) of said second non-linear conversion means for receiving said present reconstructed data sample x̂ n , another input connected to said first delay means (67) for receiving said previous received signal sample y n-1 , and having an output; and - subtracting means (49) having its two inputs connected to the outputs of said first and second multiplying means, for subtracting the output of said first multiplying means from the output of said second multiplying means, and furnishing at its own output (57) the generated difference as said timing gradient value Δτ n .
Claim 6
Dependent Claim
215 words
Apparatus in accordance with claim 1, characterized in that said reconstruction means (43A) comprises: - first non-linear conversion means (51 A) connected to said second delay means (61A) for receiving said first previous reconstructed data sample x̂ n-j , and furnishing on its output (65A) one of two possible given values (+ e , - e) as basic threshold value in response to the sign of said first previous reconstructed data sample x̂ n-j ; - adding means (75, 77) connected to the output (65A) of said first non-linear conversion means, for adding two different increment values (+ 8, - 5) to said basic threshold value, and furnishing two separate threshold values ( , ) on its outputs; and - second non-linear conversion means (53A) having a first and a second input connected to the outputs of said adding means (75, 77) for receiving said two separate threshold values ( , η - n ), and a third input connected to said common input (55A) for receiving a present received signal sample y n , and furnishing on its output (59A) one of three possible data amplitude values (+ 2A , 0 , - 2A) as reconstructed data sample x̂ n in response to said present received signal sample and said two separate threshold values.
Claim 7
Dependent Claim
126 words
Apparatus in accordance with claim 1 or claim 5, characterized in that - said first delay means (67A) comprises two delay stages (67A(1), 67A(2)) having a total delay of two sampling time periods, providing at its output a delayed received signal sample y n-2 . which constitutes said previous received signal sample y n-i , and - said second delay means (61 A) comprises two delay stages (61A(1), 61A(2)) in series, the first (61A(1)) of said delay stages providing at its output a delayed reconstructed data sample x̂ n-1 as a second previous reconstructed data sample, and the second (61A(2)) of said delay stages providing at its output another delayed reconstructed data sample x̂ n-2 which constitutes said first previous reconstructed data sample x̂ n-j .
Claim 8
Dependent Claim
144 words
Apparatus in accordance with claim 6, characterized in that said timing gradient generation means (41A) comprises: - subtracting means (71) having one input connected to said common input (55A) for receiving said present received signal sample y n , another input connected to said first delay means (67A) for receiving said previous received signal sample y n . 2 , and having an output for furnishing the difference of its two input values; and - multiplying means (73) having one input connected to the output of said first delay stage (61A(1)) of said second delay means for receiving said second previous reconstructed data sample x̂ n-1 , and another input connected to the output of said subtracting means (71) for receiving said difference, and furnishing at its output (57A) the product of its two input values as said timing gradient value Δτ n .
Claim 9
Independent Claim
165 words
A method for acquiring, in response to a received known preamble, the sampling time phase τ n in a receiver for data having been sent or recorded as partial-response (PR) signals, said method comprising the steps of: (a) sending as said preamble a data sequence of the form + 1 + 1 -1 -1 + 1 + 1 ... ; and at each sampling time (b) developing a reconstructed data sample x̂ n from the present received signal sample y n and at least a first previous reconstructed data sample x̂ n-j ; (c) developing a stochastic timing phase gradient Δτ n from the present received signal sample y n , at least one previous received signal sample y n-1 , and at least a second previous reconstructed data sample x̂ n-i ; and (d) using said stochastic timing phase gradient Δτ n as a correcting term for obtaining a new timing phase value τ n+1 from a preceding timing phase value τ n .
Claim 10
Independent Claim
165 words
A method for acquiring, in response to a received known preamble, the sampling time phase τ n in a receiver for data having been sent or recorded as partial-response (PR) signals, said method comprising the steps of: (a) sending as said preamble a data sequence of the form + 1 + 1 -1 -1 + 1 + 1 ... ; and at each sampling time (b) developing a reconstructed data sample x̂ n from the present received signal sample y n and at least a first previous reconstructed data sample x̂ n-j ; (c) developing a stochastic timing phase gradient Δτ n from the present received signal sample y n , at least one previous received signal sample y n-1 , and at least a second previous reconstructed data sample x̂ n-i ; and (d) using said stochastic timing phase gradient Δτ n as a correcting term for obtaining a new timing phase value τ n+1 from a preceding timing phase value τ n .
Claim 11
Dependent Claim
91 words
Method in accordance with claim 8, in which said step (b) comprises the following steps: - selecting one of two given values (+ ∈ , - E ) as threshold value η n in response to the sign of said first previous reconstructed data sample x̂ n-j ; and - selecting, in response to the difference between said threshold value η n and the present received signal sample y n , one of two possible data amplitude values (+ 2 , - 2) as new reconstructed data sample x̂ n .
Claim 12
Dependent Claim
159 words
Method in accordance with claim 8 or 9, comprising the following additional steps: - delaying said present received signal sample y n by one sample time period to provide a delayed sample y n-1 as said previous received signal sample, and delaying said reconstructed data sample x̂ n by one and by two sample time periods to provide a sample x̂ n-2 as said first previous reconstructed data sample and another sample x̂ n-1 as said second previous reconstructed data sample; and - developing said stochastic timing phase gradient Δτ n by providing as a first auxiliary value the product of said present received signal sample y n and said second previous reconstructed data sample x̂ n-1 ; providing as a second auxiliary value the product of said previous received signal sample y n-1 and said present reconstructed data sample x̂ n ; and providing a difference value in subtracting said first auxiliary value from said second auxiliary value.
Claim 13
Dependent Claim
146 words
Method in accordance with claim 8, in which said step (b) comprises the following steps: - selecting one of two given values (+ ∈ , - E) as basic threshold value in response to the sign of said first previous reconstructed data sample x̂ n-j ; - adding a positive (+ 5) and a negative (-δ) increment value to said basic threshold value to generate two different threshold values and ; and - selecting one of three possible data amplitude values (+ 2A , 0 , - 2A) as new reconstructed data sample x̂ n depending on the fact whether the present received signal sample y n is equal to or greater than the greater of said two different threshold values, or has a value between said two different threshold values, or is equal to or less than the smaller of said two different threshold values.
Claim 14
Dependent Claim
136 words
Method in accordance with claim 8 or 11, comprising the following additional steps: - delaying said present received signal sample y n by two sample time periods to provide a delayed sample Yn . 2 as said previous received signal sample, and delaying said reconstructed data sample x̂ n by one and by two sample time periods to provide a sample x̂ n-2 as said first previous reconstructed data sample and a sample x̂ n-1 as said second previous reconstructed data sample; and - developing said stochastic timing phase gradient Δτ n by first providing a difference value in subtracting said present received signal sample y n from said previous received signal sample y n-2 , and by finally providing the product of said difference value and said second previous reconstructed data sample x̂ n-1 .
Claim 15
Dependent Claim
89 words
Method in accordance with claim 8, comprising the following additional step: - obtaining a new timing phase value τ n+1 on the basis of the current timing phase value τ n and the current timing phase gradient Δτ n by generating τ n+1 = Tn + k 1 • Δτ n - AT n , where ATn = ΔT n-1 + k2 •Δτ n-1 , and ki and k 2 are preselected constant values; ro being the random timing phase occurring at the beginning of the phase acquisition procedure.
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