Patent US4745625A successfully refreshed from Google Patents.
US4745625A
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Transition detector
Assignee: Motorola Solutions Inc
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Filing: 1986-03-12
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Granted: 1988-05-17
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Expires: 2006-03-12
Abstract
Abstract The unknown time when a transition in a signal point sequence has occurred is determined by a trellis technique based on known subsequences of symbols that preceded and followed the transition.
Inventors
- 👤 Vedat M. Eyuboglu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:56
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/32; H04L27/34; H04L27/38; H04L27/01; H04L7/00; H04L7/04; H04L7/041; H04L7/046
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
122 words
A receiver comprising means for deriving from a received signal a sequence of signal points, each said signal point comprising a symbol and a distortion sample, said sequence comprising a first periodic subsequence of said symbols ending at an unknown time instant, and a second periodic subsequence of said symbols beginning at said unknown time instant, one period of each said first and second subsequences being known to said receiver, and means for determining said unknown time instant from said derived sequence by comparing measures, with respect to said sequence of signal points derived by said receiver, of sequences corresponding to all possible combinations of said first and second subsequences, said combinations corresponding to different possible positions of said unknown time instant.
Claim 2
Dependent Claim
122 words
A receiver comprising means for deriving from a received signal a sequence of signal points, each said signal point comprising a symbol and a distortion sample, said sequence comprising a first periodic subsequence of said symbols ending at an unknown time instant, and a second periodic subsequence of said symbols beginning at said unknown time instant, one period of each said first and second subsequences being known to said receiver, and means for determining said unknown time instant from said derived sequence by comparing measures, with respect to said sequence of signal points derived by said receiver, of sequences corresponding to all possible combinations of said first and second subsequences, said combinations corresponding to different possible positions of said unknown time instant.
Claim 3
Dependent Claim
23 words
The receiver of claim 1 wherein said unknown time instant is determined by a trellis-type sequence estimation technique whose trellis has two states.
Claim 4
Dependent Claim
18 words
The receiver of claim 1 wherein the periods of said first and second periodic subsequences are the same.
Claim 5
Dependent Claim
17 words
The receiver of claim 3 wherein the periods of said first and second periodic subsequences are 2.
Claim 6
Dependent Claim
31 words
The receiver of claim 4 wherein said first periodic subsequence comprises alternating complex numbers denoted A and B, and said second periodic subsequence comprises alternating complex numbers denoted C and D.
Claim 7
Dependent Claim
36 words
The receiver of claim 5 wherein said complex numbers represent signal amplitude and phase, and said amplitudes are the same and said phases are 180 degrees apart for A and C, and for B and D.
Claim 8
Dependent Claim
47 words
The receiver of claim 3 wherein the periods of said first and second periodic subsequences are one and said first periodic subsequence comprises A, said second periodic subsequence comprises C, and said amplitudes are the same and said phases are 180 degrees apart for A and C.
Claim 9
Dependent Claim
11 words
The receiver of claim 1 wherein said second subsequence is zero.
Claim 10
Dependent Claim
61 words
The receiver of claim 1 wherein for a given symbol s k-1 that appears in said first subsequence immediately prior to said unknown time instant, the first symbol s K that appears in said second subsequence immediately after said unknown time instant may only be one of a predetermined set of fewer than all of the symbols in said second subsequence.
Claim 11
Dependent Claim
26 words
The receiver of claim 9 wherein for successive symbols in said first subsequence the corresponding symbols s K appear in the order of said second subsequence.
Claim 12
Dependent Claim
23 words
The receiver of claim 9 wherein said symbol s K may only be a predetermined one of said symbols in said second subsequence.
Claim 13
Dependent Claim
27 words
The receiver of claim 1 further comprising means for coupling said receiver to a noise-affected channel driven by a transmitter in accordance with said subsequences of symbols.
Claim 14
Dependent Claim
11 words
The receiver of claim 12 wherein said symbols are complex numbers.
Claim 15
Dependent Claim
31 words
The receiver of claim 1 wherein said measures are computed iteratively only for sequences which for a given iteration have accumulated the minimum measure among all sequences with the same future.
Claim 16
Dependent Claim
28 words
The receiver of claim 14 wherein a final determination is made when, after an iteration, the minimum measure sequence has undergone a transition at least D iterations earlier.
Claim 17
Dependent Claim
27 words
The receiver of claim 14 further comprising a reference generator for delivering to said means for determining a sequence of reference symbols corresponding to said known sequences.
Claim 18
Dependent Claim
42 words
The receiver of claim 14 wherein said means for determining and comparing measures comprises means for calculating with respect to each said signal point in said sequence its squared distance respectively from symbols belonging to said first subsequence and said second subsequence.
Claim 19
Dependent Claim
20 words
The apparatus of claim 14 wherein said means for determining further comprises means for storing values indicative of said measures.
Claim 20
Dependent Claim
20 words
The apparatus of claim 14 wherein said means for determining further comprises means for generating normalized versions of said measures.
Claim 21
Dependent Claim
19 words
The receiver of claim 14 further comprising a means for generating a tentative determination earlier than said delayed determination.
References Cited (Backward Citations)
US4041391A
Cited
US4308617A
Cited
US4253186A
Cited
US4262360A
Cited
US4290139A
Cited
US4293953A
Cited
US4320517A
Cited
US4355397A
Cited
US4347619A
Cited
US4447908A
Cited
US4416015A
Cited
US4462108A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-05-17 | 1991-11-16 | 1992-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-17 | 1995-11-16 | 1996-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-17 | 1999-11-16 | 2000-05-17 | $7700.00 | Window Closed / Lapsed |