EP0318332A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Synchronisation of digital communications network
Assignee: British Telecommunications PLC
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Filing: 1988-11-28
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Granted: —
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Expires: 2008-11-28
Abstract
Abstract A communications network comprising a central station (4), a plurality of outstations (8), a transmission medium in the form of a branch arrangement between the central station and the outstations which carries in use multiplexed signals for the outstations in the form of a stream of broadcast frames each including a synchronisation signal, said network being adapted for return signals from the outstations to be multiplexed passively in a stream of return frames onto said transmission medium, or onto a similar transmission medium specifically for said return signals; wherein for establishing synchronisation of signals returning to the central station from the outstations the central station comprises means for transmitting a first signal to the outstations, means responsive to the time of receipt of a respective second signal from an outstation to calculate a respective delay for the respective second signal and to transmit a respective third signal to the outstation representative of the respective delay; and each outstation comprises means responsive to receipt of said first signal to transmit said second signal in a predetermined relationship with a received synchronisation signal and means responsive to said third signal to delay the transmission of said second signal by the appropriate amount whereby the second signals from all transmitting outstations are received simultaneously at the central station and effectively form a single synchronising signal for the return multiplexed signals.
Inventors
- 👤 John William Ballance
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 14:53
CPC Classifications
H; H04; H04J; H04J3/00; H04J3/02; H04J3/06; H04J3/0635; H04J3/0682; H04B; H04B10/00; H04B10/27; H04B10/272; H04B10/50; H04J14/00; H04J14/08; H04J3/0602; H04J3/0605; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03828; H04L25/03866
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
225 words
A communications network comprising a central station, a plurality of outstations, a transmission medium in the form of a branch arrangement between the central station and the outstations which carries in use multiplexed signals for the outstations in the form of a stream of broadcast frames each including a synchronisation signal, said network being adapted for return signals from the outstations to be multiplexed passively in a stream of return frames onto said transmission medium, or onto a similar transmission medium specifically for said return signals; wherein for establishing synchronisation of signals returning to the central station from the outstations the central station comprises means for transmitting a first signal to the outstations, means responsive to the time of receipt of a respective second signal from an outstation to calculate a respective delay for the respective second signal and to transmit a respective third signal to the outstation representative of the respective delay; and each outstation comprises means responsive to receipt of said first signal to transmit said second signal in a predetermined relationship with a received synchronisation signal and means responsive to said third signal to delay the transmission of said second signal by the appropriate amount whereby the second signals from all transmitting outstations are received simultaneously at the central station and effectively form a single synchronising signal for the return multiplexed signals.
Claim 2
Dependent Claim
225 words
A communications network comprising a central station, a plurality of outstations, a transmission medium in the form of a branch arrangement between the central station and the outstations which carries in use multiplexed signals for the outstations in the form of a stream of broadcast frames each including a synchronisation signal, said network being adapted for return signals from the outstations to be multiplexed passively in a stream of return frames onto said transmission medium, or onto a similar transmission medium specifically for said return signals; wherein for establishing synchronisation of signals returning to the central station from the outstations the central station comprises means for transmitting a first signal to the outstations, means responsive to the time of receipt of a respective second signal from an outstation to calculate a respective delay for the respective second signal and to transmit a respective third signal to the outstation representative of the respective delay; and each outstation comprises means responsive to receipt of said first signal to transmit said second signal in a predetermined relationship with a received synchronisation signal and means responsive to said third signal to delay the transmission of said second signal by the appropriate amount whereby the second signals from all transmitting outstations are received simultaneously at the central station and effectively form a single synchronising signal for the return multiplexed signals.
Claim 3
Dependent Claim
19 words
A network as claimed in Claim 1 wherein each second signal is in the form of a single pulse.
Claim 4
Dependent Claim
74 words
A network as claimed in Claim 1 or Claim 2 wherein each outstation is arranged, in use, to transmit a respective fourth signal delayed from said respective second signal by a respective predetermined amount; and the central station is arranged to monitor the received fourth signals, to determine when a fourth signal is not in its predetermined position and to transmit a respective correction signal to the respective outstation, and thereby maintain outstation synchronisation.
Claim 5
Dependent Claim
19 words
A network as claimed in Claim 3 wherein each fourth signal is in the form of a single pulse.
Claim 6
Dependent Claim
25 words
A network as claimed in either Claim 3 or Claim 4 wherein the correction signal is a further third signal representative of the required delay.
Claim 7
Dependent Claim
36 words
A network as claimed in either Claim 3 or Claim 4 wherein the correction signal is a fifth signal representative of an increment or decrement required of the delay previously transmitted via said respective third signal.
Claim 8
Independent Claim
219 words
A method of establishing outstation synchronisation in a return frame in a communication network comprising a central station, a plurality of outstations, a transmission medium in the form of a branch arrangement between the central station and the outstations which carries in use multiplexed signals in the form of a stream of broadcast frames each including a synchronisation signal, the network being adapted for return signals from the outstations to be multiplexed passively in a stream of return frames onto said transmission medium, or onto a similar transmission medium specifically for the return signals: which method comprises the steps of sending a first command signal to a selected outstation to cause it to send to the central station a return synchronisation signal in a predetermined relationship with a received synchronisation signal, receiving at the central station the return synchronisation signal and determining the time difference between the time of receipt of the return synchronisation signal and a required time for the synchronisation signal in the return frame, sending a second command signal to the selected outstation representative of said time difference to cause it to change said predetermined relationship in accordance with said second command signal whereby subsequent return synchronisation signals from said selected outstations are received at the central station at said required time in the return frames.
Claim 9
Independent Claim
219 words
A method of establishing outstation synchronisation in a return frame in a communication network comprising a central station, a plurality of outstations, a transmission medium in the form of a branch arrangement between the central station and the outstations which carries in use multiplexed signals in the form of a stream of broadcast frames each including a synchronisation signal, the network being adapted for return signals from the outstations to be multiplexed passively in a stream of return frames onto said transmission medium, or onto a similar transmission medium specifically for the return signals: which method comprises the steps of sending a first command signal to a selected outstation to cause it to send to the central station a return synchronisation signal in a predetermined relationship with a received synchronisation signal, receiving at the central station the return synchronisation signal and determining the time difference between the time of receipt of the return synchronisation signal and a required time for the synchronisation signal in the return frame, sending a second command signal to the selected outstation representative of said time difference to cause it to change said predetermined relationship in accordance with said second command signal whereby subsequent return synchronisation signals from said selected outstations are received at the central station at said required time in the return frames.
Claim 10
Dependent Claim
20 words
A method as claimed in Claim 7 wherein said return synchronisation signal is in the form of a single pulse.
Claim 11
Independent Claim
181 words
A method of maintaining outstation synchronisation in an communications network comprising a central station, a plurality of outstations, a transmission medium in the form of a branch arrangement between the central station and the outstations which carries in use multiplexed signals in the form of a stream of broadcast frames each including a synchronisation signal, the network being adapted for return signals from the outstations to be multiplexed passively in a stream of return frames onto said transmission medium, or onto a similar transmission medium specifically for the return signals:, wherein each outstation sends a respective synchronisation check signal at a respective predetermined time in a return frame, receiving at the central station the synchronisation check signals, determining any deviation from the expected times of receipt of the respective synchronisation check signals and sending a respective command signal to each outstation whose synchronisation check signal has not been received at the respective expected time to cause it to change the timing of its return signals in accordance with the respective command signal and thereby return to synchronisation within the return frames.
Claim 12
Independent Claim
181 words
A method of maintaining outstation synchronisation in an communications network comprising a central station, a plurality of outstations, a transmission medium in the form of a branch arrangement between the central station and the outstations which carries in use multiplexed signals in the form of a stream of broadcast frames each including a synchronisation signal, the network being adapted for return signals from the outstations to be multiplexed passively in a stream of return frames onto said transmission medium, or onto a similar transmission medium specifically for the return signals:, wherein each outstation sends a respective synchronisation check signal at a respective predetermined time in a return frame, receiving at the central station the synchronisation check signals, determining any deviation from the expected times of receipt of the respective synchronisation check signals and sending a respective command signal to each outstation whose synchronisation check signal has not been received at the respective expected time to cause it to change the timing of its return signals in accordance with the respective command signal and thereby return to synchronisation within the return frames.
Claim 13
Dependent Claim
20 words
A method as claimed in Claim 9 wherein each outstation sends a respective synchronisation check signal in each return frame.
Claim 14
Dependent Claim
25 words
A method as claimed in either Claim 9 or Claim 10 wherein the respective synchronisation check signals are in the form of a single pulse.
References Cited (Backward Citations)
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