EP0102222A2
Expired / Lapsed
EP
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Loop transmission system and method of controlling its loop-back condition
Assignee: Fujitsu Ltd
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Filing: 1983-08-18
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Granted: —
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Expires: 2003-08-18
Abstract
Abstract @ A loop transmission system comprises a plurality of node stations (ND-A...ND-D), a supervisory station (SV), and two duplicate loop transmission lines (TL1, TL2) which transmit signals in opposite directions. In operation of the system, the supervisory station sends out loop-back commands (LB-0 ON, LB-1 ON) via both of the duplicate loop transmission lines when faults are detected on both of the transmission lines at the same time. Upon receipt of a loop-back command, each of the node stations establishes a loop-back path (TLC) while retaining a connection path to a succeeding note station. The supervisory station then sends release commands (LB-0 OFF, LB-1 OFF) to the node stations, and the loop-back path is released only in those node stations which receive signals normally from both of the duplicate loop transmission lines.
Inventors
- 👤 Akira Takeyama
- 👤 Kenshi Tazaki
- 👤 Satoshi Nojima
- 👤 Norihiro Aritaka
- 👤 Teruyoshi Mita
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 17:47
CPC Classifications
H; H04; H04J; H04J3/00; H04J3/02; H04J3/08; H04B; H04B1/00; H04B1/74; H04B1/745; H04L; H04L1/00; H04L1/24; H04L1/242; H04L1/243; H04L12/00; H04L12/28; H04L12/42; H04L12/437
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
155 words
A loop transmission system comprising a plurality of node stations (ND-A...ND-D); a supervisory station (SV); and duplicate loop transmission lines (TL1, TL2) which transmit signals in opposite directions; characterised by means in the supervisory station to feed loop-back commands (LB-0 ON, LB-1 ON) to both of the duplicate loop transmission lines when faults are detected on both of the duplicate loop transmission lines at the same time and subsequently to feed release commands (LB-0 OFF, LB-1 OFF) to both of the duplicate transmission lines; means (TLC) in each of the node stations to establish a loop-back path while retaining a connection path to a succeeding node station upon the receipt of a loop-back command; and means (LBC) in each node station responsive to the release commands to cause the loop-back path to be released in the respective node station only if that node station receives signals normally from both of the duplicate loop transmission lines.
Claim 2
Dependent Claim
155 words
A loop transmission system comprising a plurality of node stations (ND-A...ND-D); a supervisory station (SV); and duplicate loop transmission lines (TL1, TL2) which transmit signals in opposite directions; characterised by means in the supervisory station to feed loop-back commands (LB-0 ON, LB-1 ON) to both of the duplicate loop transmission lines when faults are detected on both of the duplicate loop transmission lines at the same time and subsequently to feed release commands (LB-0 OFF, LB-1 OFF) to both of the duplicate transmission lines; means (TLC) in each of the node stations to establish a loop-back path while retaining a connection path to a succeeding node station upon the receipt of a loop-back command; and means (LBC) in each node station responsive to the release commands to cause the loop-back path to be released in the respective node station only if that node station receives signals normally from both of the duplicate loop transmission lines.
Claim 3
Dependent Claim
39 words
A system according to Claim 1, characterised in that the loop-back path is released only in the node stations (ND-A...ND-D) which receive the release commands (LB-0 OFF, LB-1 OFF) from both of the duplicate loop transmission lines (TL1, TL2).
Claim 4
Dependent Claim
40 words
A system according to Claim 2, characterised in that the loop-back path is released only in the node stations (ND-A...ND-D) which receive the same release commands (LB-0 OFF, LB-1 OFF) from both of the duplicate loop transmission lines (TLI, TL2).
Claim 5
Dependent Claim
50 words
A system according to Claim 1, characterised in that the loop-back path is released only in the node stations (ND-A...ND-D) which receive a release command (LB-0 OFF, LB-1 OFF) from one of the duplicate transmission lines (TL1, TL2) and receive signals normally from the other of the duplicate transmission lines.
Claim 6
Dependent Claim
45 words
A system according to Claim 4, characterised in that the node stations (ND-A...ND-D) determine whether the signals are received normally when the signals have a magnitude larger than a predetermined value and when the synchronisation of clock pulses extracted from the signals is not disturbed.
Claim 7
Dependent Claim
146 words
A loop transmission system comprising a plurality of node stations (ND-A...ND-D); a supervisory station (SV); and two duplicate loop transmission lines (TL1, TL2) which transmit signals in opposite directions; characterised in that each node station comprises a connection line (TLC) for returning signals received from one of the duplicate loop transmission lines to the other of the duplicate loop transmission lines; and a control circuit (LBC) for controlling the turning on and the turning off of the connection line, the control circuit turning on the connection line in accordance with a loop-back command (LB-0 ON, LB-1 ON) transmitted from the supervisory station (SV) and turning off the connection line when a release command (LB-0 OFF, LB-1 OFF) is transmitted from the supervisory station after the transmission of the loop-back command and when the node station receives signals normally from both of the duplicate loop transmission lines.
Claim 8
Dependent Claim
146 words
A loop transmission system comprising a plurality of node stations (ND-A...ND-D); a supervisory station (SV); and two duplicate loop transmission lines (TL1, TL2) which transmit signals in opposite directions; characterised in that each node station comprises a connection line (TLC) for returning signals received from one of the duplicate loop transmission lines to the other of the duplicate loop transmission lines; and a control circuit (LBC) for controlling the turning on and the turning off of the connection line, the control circuit turning on the connection line in accordance with a loop-back command (LB-0 ON, LB-1 ON) transmitted from the supervisory station (SV) and turning off the connection line when a release command (LB-0 OFF, LB-1 OFF) is transmitted from the supervisory station after the transmission of the loop-back command and when the node station receives signals normally from both of the duplicate loop transmission lines.
Claim 9
Dependent Claim
70 words
A system according to Claim 6, characterised in that each of the node stations (ND-A...ND-D) comprises a level error detecting circuit (LV) which outputs a level error signal (E RL ) when the signals have a magnitude smaller than a predetermined value and a clock error detecting circuit (CSC) which outputs a clock error signal (E RC ) when the synchronisation of clock pulses extracted from the signals is disturbed.
Claim 10
Dependent Claim
54 words
A system according to Claim 7, characterised in that the node stations (ND-A...ND-D) determine whether the signals are received normally when the level error detecting circuit (LV) does not output the level error signal (E RL ) and the clock error detecting circuit (CSC) does not output the clock error signal (E RC ).
Claim 11
Dependent Claim
108 words
A system according to Claim 7 or Claim 8, characterised in that the node stations (ND-A...ND-D) comprise a command receiving circuit (CMR) for detecting commands sent from the supervisory station (SV); a loop-back control circuit (LBC) which outputs loop-back signals (LB-0, LB-l) in accordance with the commands received by the command receiving circuit, the level error signal (E RL ) supplied from the level error detecting sircuit (LV), and the clock error signal (E RC ) supplied from the clock error detecting circuit (CSC); and a transmission line switching circuit (TLC) which extablishes a loop-back path in accordance with the loop-back signals output from the loop-back control circuit.
Claim 12
Independent Claim
149 words
A method of controlling the loop-back condition of a loop transmission system comprising a plurality of node stations (ND-A...ND-D), a supervisory station (SV), and two duplicate loop transmission lines (TL1, TL2) which transmit signals in opposite directions, characterised in that the supervisory station sends out loop-back commands (LB-0 ON, LB-1 ON) to both of the duplicate loop transmission lines when faults are detected on both of the duplicate loop transmission lines at the same time; in that each of the node stations establishes a loop-back path (TLC) while retaining a connection path to a succeeding node station upon the receipt of a loop-back command; and in that the loop-back path is released only in those node stations which receive signals normally from both of the duplicate loop transmission lines when the supervisory station sends release commands (LB-0 OFF, LB-I OFF) to the node stations after sending the loop-back commands.
Claim 13
Independent Claim
149 words
A method of controlling the loop-back condition of a loop transmission system comprising a plurality of node stations (ND-A...ND-D), a supervisory station (SV), and two duplicate loop transmission lines (TL1, TL2) which transmit signals in opposite directions, characterised in that the supervisory station sends out loop-back commands (LB-0 ON, LB-1 ON) to both of the duplicate loop transmission lines when faults are detected on both of the duplicate loop transmission lines at the same time; in that each of the node stations establishes a loop-back path (TLC) while retaining a connection path to a succeeding node station upon the receipt of a loop-back command; and in that the loop-back path is released only in those node stations which receive signals normally from both of the duplicate loop transmission lines when the supervisory station sends release commands (LB-0 OFF, LB-I OFF) to the node stations after sending the loop-back commands.
Claim 14
Dependent Claim
40 words
A method according to Claim 10, characterised in that the loop-back path (TLC) is released only in those node stations (ND-A...ND-D) which receive the release commands (LB-0 OFF, LB-1 OFF) from both of the duplicate loop transmission lines (TL1, TL2).
Claim 15
Dependent Claim
40 words
A method according to Claim 11, characterised in that the loop-back path (TLC) is released only in those node stations which receive the same release commands (LB-0 OFF, LB-1 OFF) from both of the duplicate loop transmission lines (TL1, TL2).
Claim 16
Dependent Claim
51 words
A method according to Claim 10, characterised in that the loop-back path (TLC) is released only in those node stations (ND-A...ND-D) which receive the release command (LB-0 OFF, LB-1 OFF) from one of the duplicate transmission lines (TL1, TL2) and receive signals normally from the other of the duplicate transmission lines.
Claim 17
Dependent Claim
45 words
A method according to Claim 10, characterised in that the node stations (ND-A...ND-D) determine whether the signals are received normally when the signals have a magnitude larger than a predetermined value and when the synchronisation of clock pulses extracted from the signals is not disturbed.
References Cited (Backward Citations)
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