US3787665A
Expired / Lapsed
US
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Means for synchronizing remotely positioned timing devices
Assignee: McDonnell Douglas Corp
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Filing: 1972-07-17
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Granted: 1974-01-22
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Expires: 1992-07-17
Abstract
Abstract Improvements in means for synchronizing remotely positioned timing devices including means to provide multiple error correction factors which are functions of the time error or time difference between the time keeping means in spaced systems or units being synchronized, said means being particularly useful in group synchronization by providing time convergence to a common synchronizing base. The use of multiple error correction factors restricts or limits relative timing errors between systems or units especially when in the process of changing from one reference time base location to another, and it provides means to bring timing devices at remote locations into closer synchronization on a continuing basis. The present means provide correction factors which are directly proportional to the synchronizing error including those cases where the correction versus error proportion is other than in a one-to-one relationship. This is especially advantageous in situations where there is a ground or master station responsibility that is shared on a rotating, shifting or location basis with other stations that are or may be synchronized but on a different time schedule or time base. Partial corrections in such situations can cause convergence of the synchronizing operation on a global or regional basis to a common time synchronization base and on a continuous and uninterrupted basis. The present means are also able to provide time synchronization of remotely located timing devices or units with or without the need to designate specific units or stations, or sets of units or stations, as masters and slaves. This means that the need for master or central accurately synchronized time references or stations which has characterized prior art time synchronized systems is no longer necessary.
Inventors
- 👤 F Watson
- 👤 J Mohr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:40
CPC Classifications
G; G01; G01S; G01S11/00; G01S11/02; G01S11/08; G04; G04R; G04R40/00; G04R40/06; H; H04; H04B; H04B7/00; H04B7/14; H04B7/15; H04B7/185; H04B7/18502
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
282 words
Means for maintaining a condition close to but not necessarily exactly of synchronism at a plurality of spaced units each of which includes means capable of keeping time in the same length repeating time periods, the amount of difference between the time of occurrence of corresponding time periods at communicating units being the out-of synchronism error, means (144) for assigning a different distinctive time period to each cooperating unit as its synchronizing time, means (136a and 136b) included in each unit for establishing an initial counting rate at the beginning of each occurrence of its assigned time period, means (136a, 136c) at each unit for establishing a second counting rate thereat different from the initial counting rate, means (22) at selected ones of said units for transmitting a signal therefrom beginning at the beginning of each occurrence of the time periods assigned thereto, means (24) at other of said cooperating units within range of said transmitting units for receiving said signals in the same time periods assigned to the said transmitting units and for transmitting reply signals at later times in the same time periods based at least in part on the time of receipt of each such transmItted signals, means (138, 142, 150, 152, 154, 156) at each of said transmitting units for changing the counting rate thereat from the initial counting rate to the second counting rate in response to the receipt in the same time period of the reply signal, the ratio of the initial counting rate before receipt of the reply signal to the second counting rate after receipt of said reply signal being selectable to produce a time error correction that is different from the out-of-synchronism error.
Claim 2
Dependent Claim
282 words
Means for maintaining a condition close to but not necessarily exactly of synchronism at a plurality of spaced units each of which includes means capable of keeping time in the same length repeating time periods, the amount of difference between the time of occurrence of corresponding time periods at communicating units being the out-of synchronism error, means (144) for assigning a different distinctive time period to each cooperating unit as its synchronizing time, means (136a and 136b) included in each unit for establishing an initial counting rate at the beginning of each occurrence of its assigned time period, means (136a, 136c) at each unit for establishing a second counting rate thereat different from the initial counting rate, means (22) at selected ones of said units for transmitting a signal therefrom beginning at the beginning of each occurrence of the time periods assigned thereto, means (24) at other of said cooperating units within range of said transmitting units for receiving said signals in the same time periods assigned to the said transmitting units and for transmitting reply signals at later times in the same time periods based at least in part on the time of receipt of each such transmItted signals, means (138, 142, 150, 152, 154, 156) at each of said transmitting units for changing the counting rate thereat from the initial counting rate to the second counting rate in response to the receipt in the same time period of the reply signal, the ratio of the initial counting rate before receipt of the reply signal to the second counting rate after receipt of said reply signal being selectable to produce a time error correction that is different from the out-of-synchronism error.
Claim 3
Dependent Claim
35 words
The means defined in claim 1 wherein the ratio of the initial counting rate before receipt of the reply signal to the second counting rate after receipt of the reply signal is greater than one.
Claim 4
Dependent Claim
35 words
The means defined in claim 1 wherein the ratio of the initial counting rate before receipt of the reply signal to the second counting rate after receipt of the reply signal is less than one.
Claim 5
Dependent Claim
41 words
The means defined in claim 1 wherein all cooperating units include means for shifting the time of occurrence of the repeating time periods thereat in a direction to make the later occurrences thereof occur more nearly simultaneously at all cooperating units.
Claim 6
Dependent Claim
18 words
The means defined in claim 1 wherein the ratio of the said counting rates is other than two-to-one.
Claim 7
Dependent Claim
310 words
Means to cause time keeping means at a plurality of remotely positioned devices in a system to converge on a system-wide bases toward a common synchronized condition comprising a plurality of spaced units each of which includes means capable of keeping time in the same length repeating time periods, means dividing the time periods into a plurality if distinct message slots for assignment to respective ones of the cooperating units as its time for transmitting, receiving and synchronizing, means in each unit for establishing an initial time keeping rate commencing at the beginning of each occurrence of its assigned message slot, means at each unit for establishing a second counting rate thereat different from the initial time keeping rate, other means at each unit for receiving signals transmitted by other cooperating units within range thereof and in the message slots assigned to said other units, means at each receiving unit for transmitting a reply signal at a later time in the same message slot based on the time of receipt of the said received signal, means at each unit operable in its assigned message slot and responsive to receipt of the reply signal for changing by shifting the times of occurrence of future occurrences of the said time periods and of the message slots therein based on the time keeping means reaching a predetermined count, said means responsive to the time of receipt of the reply signal including means to change from the initial to the second time keeping rate, the ratio of the difference between the times of occurrence of the message slots at two cooperating units before receipt of said reply signal to the correction introduced by shifting the times of occurrence thereof after receipt of the reply signal during the same message slot and until the predetermined count is reached being other than in a one-to-one relationship.
Claim 8
Dependent Claim
310 words
Means to cause time keeping means at a plurality of remotely positioned devices in a system to converge on a system-wide bases toward a common synchronized condition comprising a plurality of spaced units each of which includes means capable of keeping time in the same length repeating time periods, means dividing the time periods into a plurality if distinct message slots for assignment to respective ones of the cooperating units as its time for transmitting, receiving and synchronizing, means in each unit for establishing an initial time keeping rate commencing at the beginning of each occurrence of its assigned message slot, means at each unit for establishing a second counting rate thereat different from the initial time keeping rate, other means at each unit for receiving signals transmitted by other cooperating units within range thereof and in the message slots assigned to said other units, means at each receiving unit for transmitting a reply signal at a later time in the same message slot based on the time of receipt of the said received signal, means at each unit operable in its assigned message slot and responsive to receipt of the reply signal for changing by shifting the times of occurrence of future occurrences of the said time periods and of the message slots therein based on the time keeping means reaching a predetermined count, said means responsive to the time of receipt of the reply signal including means to change from the initial to the second time keeping rate, the ratio of the difference between the times of occurrence of the message slots at two cooperating units before receipt of said reply signal to the correction introduced by shifting the times of occurrence thereof after receipt of the reply signal during the same message slot and until the predetermined count is reached being other than in a one-to-one relationship.
Claim 9
Dependent Claim
29 words
The means defined in claim 6 wherein the relationship of the difference between the times of occurrence of the message slots and the correction introduced is greater than one.
Claim 10
Dependent Claim
29 words
The means defined in claim 6 wherein the relationship of the difference between the times of occurrence of the message slots and the correction introduced is less than one.
Claim 11
Dependent Claim
94 words
The means defined in claim 6 wherein each cooperating unit includes means for shifting the times of occurrence of its assigned message slot in a direction to make future occurrences thereof in all cooperating units occur more nearly simultaneously, the accumulative effect of the said means at all cooperating units causing the time keeping means at all said units to converge toward a condition in which all of the cooperating units are synchronized on real time which is a condition in which the occurrences of each message slot Occurs simultaneously in all cooperating units.
Claim 12
Dependent Claim
34 words
The means defined in claim 6 wherein the relationship of the difference between the times of occurrence of the message slot and the correction introduced is different in at least two spaced cooperating units.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-21 | 1977-07-23 | 1978-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-21 | 1981-07-23 | 1982-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-21 | 1985-07-23 | 1986-01-22 | $7700.00 | Window Closed / Lapsed |