US4433348A
Expired / Lapsed
US
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Apparatus and method for requiring proper synchronization of a digital data flow
Assignee: DIGITAL RECORDING A CORP OF UTAH
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Filing: 1981-09-08
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Granted: 1984-02-21
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Expires: 2001-09-08
Abstract
Abstract The synchronization circuitry can be described as operating in essentially four states and is particularly useful at startup, to locate synchronization codes and spacing there between in the data flows. In operation, the synchronization circuitry looks in a data flow at startup for any sync code and, when such sync code is found, counts ahead to where the next sync code should be. If a proper sync code is found, again the circuitry counts ahead to where the next sync code should be, continuing looking at points along the data flow until a certain number (n) of properly located sync codes are discovered whereat synchronization is declared and normal playback is ordered. However, if sync codes are not located where they should be in the data flow, then such failures are subtracted from success until either (n) successes are found or a total of successes less failures reaches zero whereat the circuitry returns to the first state of looking for any sync code.
Inventors
- 👤 Thomas G. Stockham, Jr.
- 👤 Bruce C. Rothaar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:27
CPC Classifications
G; G11; G11B; G11B27/00; G11B27/10; G11B27/19; G11B27/28; G11B27/30; G11B27/3027; G11B20/00; G11B20/10; G11B20/18; G11B20/1803
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
168 words
Apparatus for arrangement in a digital tape recorder for accurately acquiring proper synchronization for playback of a digital data flow at startup including, means for identifying synchronization codes in data words in a digital data flow; means for locking onto an identified synchronization code; locator means arranged for counting a certain number of bits from said identified synchronization code to look for a following synchronization code; counter means arranged for counting the numbers of properly located synchronization codes and failures to locate synchronization codes, which counter means will subtract the failures to locate from the properly located synchronization codes; and declaration means arranged to receive from said counter means the number of properly located synchronization codes less the failures to locate for, when a certain number of properly located synchronization codes are located, declaring synchronization and initiating recorder playback and, when the number of properly located synchronization codes less the failures to locate reaches zero, declaring synchronization not found and reactivating the means for identifying any synchronization code.
Claim 2
Dependent Claim
168 words
Apparatus for arrangement in a digital tape recorder for accurately acquiring proper synchronization for playback of a digital data flow at startup including, means for identifying synchronization codes in data words in a digital data flow; means for locking onto an identified synchronization code; locator means arranged for counting a certain number of bits from said identified synchronization code to look for a following synchronization code; counter means arranged for counting the numbers of properly located synchronization codes and failures to locate synchronization codes, which counter means will subtract the failures to locate from the properly located synchronization codes; and declaration means arranged to receive from said counter means the number of properly located synchronization codes less the failures to locate for, when a certain number of properly located synchronization codes are located, declaring synchronization and initiating recorder playback and, when the number of properly located synchronization codes less the failures to locate reaches zero, declaring synchronization not found and reactivating the means for identifying any synchronization code.
Claim 3
Dependent Claim
43 words
Apparatus for processing digital information as recited in claim 1, wherein the recorder providing for recording of alternating synchronization codes; and the means for identifying synchronization codes in said data words is programmed to looking for and act on said alternating synchronization codes.
Claim 4
Dependent Claim
83 words
Apparatus for processing digital information as recited in claim 1, wherein the apparatus functions by looking for any synchronization code, and upon finding a synchronization code counting to where a next synchronization code should be, and reflecting the present and absence of proper synchronization codes respectively as pluses and minuses together and, when a sum thereof equals a desired number, declaring synchronization and when a sum thereof equals zero, declaring synchronization not found and the process of looking for any synchronization code restarted.
Claim 5
Independent Claim
116 words
A method for accurately acquiring synchronization of digital data words coming off of a permanent media during playback including the steps of, looking for any synchronization code; counting ahead a certain number of bits in the data word and looking for a proper synchronization code; continuing counting ahead the certain number of bits in each data word and looking for proper synchronization codes; subtracting failures to locate proper synchronization codes from located proper synchronization codes; upon locating (n) proper synchronization codes, declaring synchronization and beginning playback; and where properly located synchronization codes less failures to locate proper synchronization codes equal zero, declaring synchronization not found and looking again in the data flow for any synchronization code.
Claim 6
Independent Claim
116 words
A method for accurately acquiring synchronization of digital data words coming off of a permanent media during playback including the steps of, looking for any synchronization code; counting ahead a certain number of bits in the data word and looking for a proper synchronization code; continuing counting ahead the certain number of bits in each data word and looking for proper synchronization codes; subtracting failures to locate proper synchronization codes from located proper synchronization codes; upon locating (n) proper synchronization codes, declaring synchronization and beginning playback; and where properly located synchronization codes less failures to locate proper synchronization codes equal zero, declaring synchronization not found and looking again in the data flow for any synchronization code.
References Cited (Backward Citations)
US3916440A
Cited
US4321632A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-02-20 | 1987-08-22 | 1988-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-02-20 | 1991-08-22 | 1992-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-02-20 | 1995-08-22 | 1996-02-21 | $7700.00 | Window Closed / Lapsed |