US5416623A — Optical communications system

Claim 1

Independent Claim 119 words

A line monitoring arrangement for use in an optical fibre communications system while it is also carrying system data signals, the monitoring arrangement comprising: a test sequence generator means for generating a sequence of test pulses, an optical transmitter means for repeatedly launching the sequence of test pulses into a first end of a transmission line forming part of the communications system and including means for superimposing said system data signals with said test pulses, and means for receiving signals at said first end and for correlating the signals received at the first end of the transmission line with the earlier generated sequence of test pulses to identify returned test pulse sequences reflected from points along said transmission line.

Claim 2

Dependent Claim 119 words

A line monitoring arrangement for use in an optical fibre communications system while it is also carrying system data signals, the monitoring arrangement comprising: a test sequence generator means for generating a sequence of test pulses, an optical transmitter means for repeatedly launching the sequence of test pulses into a first end of a transmission line forming part of the communications system and including means for superimposing said system data signals with said test pulses, and means for receiving signals at said first end and for correlating the signals received at the first end of the transmission line with the earlier generated sequence of test pulses to identify returned test pulse sequences reflected from points along said transmission line.

Claim 3

Dependent Claim 24 words

An arrangement as in claim 1, wherein the optical transmitter means launches test pulse sequences continuously into said first end of the transmission line.

Claim 4

Dependent Claim 23 words

An arrangement as in claim 1, wherein the optical transmitter means launches system data signals into said first end of the transmission line.

Claim 5

Dependent Claim 26 words

An arrangement as in claim 1, further comprising a second optical transmitter means for launching system data signals into said first end of the transmission line.

Claim 6

Dependent Claim 27 words

An arrangement as in claim 4, wherein the second optical transmitter means is coupled to said first end of the transmission line by a directional optical coupler.

Claim 7

Dependent Claim 44 words

An arrangement as in claim 1, wherein said means for receiving and correlating includes control means for reducing the energy level of data signals returning to said first end of the transmission line relative to the energy level of the returned test pulse sequences.

Claim 8

Dependent Claim 49 words

An arrangement as in claim 6, wherein the control means includes comparator means for applying asymmetric clipping to the signals input to the means for correlating, said comparator means clipping said signals at a level that is slightly higher than the energy level of the returned test pulse sequences.

Claim 9

Dependent Claim 109 words

An arrangement as in claim 6, wherein the control means includes: a comparator positioned between said first end of the transmission line and the correlator, and a time delay unit in parallel with the comparator, the comparator having a threshold level which is higher than the energy level of the returned test pulse sequences so that its output is substantially entirely system data signals, and the time delay unit aligning the output of the comparator with the signals received at said first end of the transmission line so that the system data signals are subtracted from said received signals, whereby substantially only returned test pulse sequences reach the correlator.

Claim 10

Dependent Claim 46 words

An arrangement as in claim 6, wherein the control means includes a non-linear element positioned between said first end of the transmission line and the correlator, the non-linear element increasing the energy level of the returned signals relative to the energy level of system data signals.

Claim 11

Dependent Claim 34 words

An arrangement as in claim 1, further comprising an optical receiver for receiving returned test pulse sequences at said first end of the transmission line, and for transmitting resultant electrical signals to the correlator.

Claim 12

Dependent Claim 22 words

An arrangement as in claim 10, wherein the optical receiver receives system data signals at said first end of the transmission line.

Claim 13

Dependent Claim 44 words

An arrangement as in claim 10, further comprising a second optical receiver for receiving system data signals at said first end of the transmission line, the second optical receiver being coupled to said first end of the transmission line by a directional optical coupler.

Claim 14

Dependent Claim 31 words

An arrangement as in claim 1, wherein the test sequence generator generates PRBS pulses at a low signal level so that system data transmission along the transmission line is substantially unaffected.

Claim 15

Dependent Claim 14 words

An arrangement as in claim 1, wherein the correlator includes a digitally-stablised analogue correlator.

Claim 16

Dependent Claim 126 words

An arrangement as in claim 14, wherein the correlator comprises: a PRBS generator having a control port, a code shift and stepping control unit connected to said control port so as to cause said PRBS generator to produce an output identical to that of the test sequence generator means but shifted in time, an analogue multiplier circuit connected to receive an output of the PRBS generator and incoming data signals and to produce as an output the product thereof, and a digitally-stablised analogue integrate and dump circuit connected to receive the output of said analogue multiplier circuit, the core shift and stepping control unit being connected to receive synchronisation and clock inputs from the test sequence generator means to synchronise the output of the PRBS generator.

Claim 17

Dependent Claim 26 words

An arrangement as in claim 1, further comprising a computer connected to the output of the correlator for displaying or recording the output of the correlator.

Claim 18

Dependent Claim 142 words

An optical fibre communications system comprising: a transmission line, means for launching system data signals into a first end of the transmission line, and a line monitoring arrangement for use in an optical fibre communications system while it is also carrying system data signals, the monitoring arrangement comprising: a test sequence generator means for generating a sequence of test pulses, an optical transmitter for repeatedly launching the sequence of test pulses into a first end of a transmission line forming part of the communications system and including means for superimposing said system data signals with said test pulses, and means for receiving signals at said first end and for correlating the signals received at the first end of the transmission line with the earlier generated sequence of test pulses to identify returned test pulse sequences reflected from points along said transmission line.

Claim 19

Dependent Claim 142 words

An optical fibre communications system comprising: a transmission line, means for launching system data signals into a first end of the transmission line, and a line monitoring arrangement for use in an optical fibre communications system while it is also carrying system data signals, the monitoring arrangement comprising: a test sequence generator means for generating a sequence of test pulses, an optical transmitter for repeatedly launching the sequence of test pulses into a first end of a transmission line forming part of the communications system and including means for superimposing said system data signals with said test pulses, and means for receiving signals at said first end and for correlating the signals received at the first end of the transmission line with the earlier generated sequence of test pulses to identify returned test pulse sequences reflected from points along said transmission line.

Claim 20

Independent Claim 96 words

A method of monitoring an optical fibre transmission line without disrupting system data signals passing thereover, the method comprising steps of: generating a sequence of test pulses, superimposing said test pulses with system data signals, repeatedly launching the superimposed sequence of test pulses and system data signals into a first end of the transmission line, receiving optical signals at the first end of the transmission line including test pulses reflected from points along the transmission line, and extracting returned test pulse sequences from the received signals by correlation with said sequence of earlier generated test pulses.

Claim 21

Independent Claim 96 words

A method of monitoring an optical fibre transmission line without disrupting system data signals passing thereover, the method comprising steps of: generating a sequence of test pulses, superimposing said test pulses with system data signals, repeatedly launching the superimposed sequence of test pulses and system data signals into a first end of the transmission line, receiving optical signals at the first end of the transmission line including test pulses reflected from points along the transmission line, and extracting returned test pulse sequences from the received signals by correlation with said sequence of earlier generated test pulses.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1998-05-15	1998-11-14	1999-05-16	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2002-05-15	2002-11-14	2003-05-16	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2006-05-15	2006-11-14	2007-05-16	$7700.00	Window Closed / Lapsed

Optical communications system

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