US4608703A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Synchronization detection system for data transmission
Assignee: Ricoh Co Ltd
•
Filing: 1984-05-09
•
Granted: 1986-08-26
•
Expires: 2004-05-09
Abstract
Abstract A synchronization detecting system for data transmission in which a two-dimensionally modulated signal is received by way of a demodulator. In a training sequence for a two-dimensional modulation modem, a point of transition from an alternation to a pseudorandom symbol sequence is detected by producing a sum of the vectors of two signals which are remote from each other by a period of two samples, or a difference therebetween. Whether the detection of the transition point has been correct is decided utilizing the alternation.
Inventors
- 👤 Mitsuru Kaga
- 👤 Shigetaka Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:42
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/32; H04L27/34; H04L27/38; H04L7/00; H04L7/04; H04L7/041; H04L7/043; H04L7/046
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
109 words
A system for detecting synchronization in data transmission which, in a training sequence for receiving a two-dimensionally modulated signal by way of a demodulator, detects a point of transition from an alternating symbol sequence of two different symbol elements to a pseudorandom symbol sequence, said system comprising: calculator means for calculating a vector sum of two signals in a signal space which are time-serially remote from each other by a period of two symbol elements; comparator means for comparing said vector sum with a predetermined threshold value; and detector means for detecting said point of transition in terms of a decrease of the vector sum beyond said threshold value.
Claim 2
Independent Claim
109 words
A system for detecting synchronization in data transmission which, in a training sequence for receiving a two-dimensionally modulated signal by way of a demodulator, detects a point of transition from an alternating symbol sequence of two different symbol elements to a pseudorandom symbol sequence, said system comprising: calculator means for calculating a vector sum of two signals in a signal space which are time-serially remote from each other by a period of two symbol elements; comparator means for comparing said vector sum with a predetermined threshold value; and detector means for detecting said point of transition in terms of a decrease of the vector sum beyond said threshold value.
Claim 3
Dependent Claim
32 words
A system as claimed in claim 1, in which the comparator means is constructed to compare the vector sum and the threshold value with respect to an absolute value of a vector.
Claim 4
Dependent Claim
28 words
A system as claimed in claim 1, in which the comparator means is constructed to compare the vector sum and the threshold value with respect to signal power.
Claim 5
Independent Claim
109 words
A system for detecting synchronization in data transmission which, in a training sequence for receiving a two-dimensionally modulated signal by way of a demodulator, detects a point of transition from an alternating symbol sequence of two different symbol elements to a pseudorandom symbol sequence, said system comprising: calculator means for calculating a vector difference between two signals in a signal space which are time-serially remote from each other by a period of two symbol elements; comparator means for comparing said vector difference with a predetermined threshold value; and detector means for detecting said point of transition in terms of an increase in the vector difference beyond said threshold value.
Claim 6
Independent Claim
109 words
A system for detecting synchronization in data transmission which, in a training sequence for receiving a two-dimensionally modulated signal by way of a demodulator, detects a point of transition from an alternating symbol sequence of two different symbol elements to a pseudorandom symbol sequence, said system comprising: calculator means for calculating a vector difference between two signals in a signal space which are time-serially remote from each other by a period of two symbol elements; comparator means for comparing said vector difference with a predetermined threshold value; and detector means for detecting said point of transition in terms of an increase in the vector difference beyond said threshold value.
Claim 7
Dependent Claim
32 words
A system as claimed in claim 4, in which the comparator means is constructed to compare the vector difference and the threshold value with respect to an absolute value of a vector.
Claim 8
Dependent Claim
28 words
A system as claimed in claim 4, in which the comparator means is constructed to compare the vector difference and the threshold value with respect to signal power.
Claim 9
Independent Claim
156 words
A system for detecting synchronization in data transmission which, in a training sequence for receiving a two-dimensionally modulated signal by way of a demodulator, detects a point of transition from an alternating symbol sequence of two different symbol elements to a pseudorandom symbol sequence, said system comprising: first detector means for detecting said point of transition; second detector means for determining whether a symbol at a first time point which is antecedent to the time point of the detection of the transition by a first predetermined period of time and a symbol at a second time point which is antecedent to the time point of the detection of the transition by a second predetermined period of time correspond to anticipated two symbol elements in the alternating symbol sequence; and decision means for deciding that the point of transition is correct when said symbols at said first and second predetermined time points correspond to said anticipated symbols.
Claim 10
Independent Claim
156 words
A system for detecting synchronization in data transmission which, in a training sequence for receiving a two-dimensionally modulated signal by way of a demodulator, detects a point of transition from an alternating symbol sequence of two different symbol elements to a pseudorandom symbol sequence, said system comprising: first detector means for detecting said point of transition; second detector means for determining whether a symbol at a first time point which is antecedent to the time point of the detection of the transition by a first predetermined period of time and a symbol at a second time point which is antecedent to the time point of the detection of the transition by a second predetermined period of time correspond to anticipated two symbol elements in the alternating symbol sequence; and decision means for deciding that the point of transition is correct when said symbols at said first and second predetermined time points correspond to said anticipated symbols.
Claim 11
Dependent Claim
31 words
A system as claimed in claim 7, in which said first and second time points are remote from each other by a period of one symbol element of a received signal.
References Cited (Backward Citations)
US3694757A
Cited
US4027250A
Cited
JPS5274207A
Cited
US4381546A
Cited
JPS561631A
Cited
US4334313A
Cited
US4433425A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-08-25 | 1990-02-24 | 1990-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-08-25 | 1994-02-24 | 1994-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-08-25 | 1998-02-24 | 1998-08-26 | $7700.00 | Window Closed / Lapsed |