Communicating Information

• US 20080219660A1
• Filed: 03/29/2006
• Published: 09/11/2008
• Est. Priority Date: 03/31/2005
• Status: Active Grant

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Healey, Peter, Sikora, Edmund
• Granted Patent: US 8,396,360 B2
• Time in Patent Office: Days
• US Class Current: 398/16
• CPC Class Codes: G01D 5/35383 using multiple sensor devices using multiplexing techniques
• CPC Class Codes: H04B 10/071 using a reflected signal, e.g. using optical time domain reflectometers [OTDR]

Abstract

The present invention relates to the communication of information where the information is introduced at a plurality of spaced apart locations onto an optical waveguide. The following steps are performed: (i) transmitting test signals onto the waveguide, components of the test signals being returned in a distributed manner along the waveguide; (ii) receiving first component signals returned from beyond a first location at which information is introduced; (iii) receiving second component signals returned from beyond a second location at which information is introduced, the second component signals being returned through the first location; and, (iv) processing the second component signals using the first component signals to distinguish information introduced at the second location from information introduced at the first location.

Claims

1. A communication method in which information is introduced at a plurality of spaced apart locations along an optical waveguide, including the steps of:

(i) transmitting test signals onto the waveguide, components of the test signals being returned in a distributed manner along the waveguide;

(ii) receiving first component signals returned from beyond a first location at which information is introduced;

(iii) receiving second component signals returned from beyond a second location at which information is introduced, the second component signals being returned through the first location; and

, (iv) performing a subtraction operation involving the second component signals and the first component signals in order to distinguish information introduced at the second location from information introduced at the first location, wherein the test signals are formed as pairs of signal copies, the signal copies of each pair being transmitted onto the waveguide with a temporal offset relative to one another.

2. A communication method as claimed in claim 1, wherein the return component signals arising from respective copies of each given pair are temporally realigned.

3. A communication method as claimed in claim 2, wherein the realigned component signals are combined interferometrically.

4. A communication method as claimed in claim 3, wherein the combined component signals succeed one another so as to form a time-distributed return signal, the combined first component signal and the combined second component signal being identifiable from their respective temporal positions in the return signal.

5. A communication method as claimed in claim 1, wherein information is introduced by modulating the test signals.

6. A communication method as claimed in claim 1, wherein an acoustic disturbance is applied to the waveguide in order to introduce information thereon.

7. A communication method as claimed in claim 1, wherein the acoustic disturbance has the form of an audio signal.

8. A communication method as claimed in claim 1, wherein the test signals are returned in by a process of distributed backscattering as the test signals travel along the waveguide.

9. Communication apparatus for receiving information that is introduced at a plurality of spaced apart locations along an optical waveguide, the apparatus including:

a source for transmitting a test signal onto the waveguide;

a receiver for receiving the test signal that has been returned in a time distributed manner along the waveguide;

timer means for evaluating return times; and

processor means configured to capture the returned test signal at a first return time and at a second return time, and to perform a subtraction operation involving the return test signal captured at the first and the second return times.

10. A communication method in which information is introduced at a plurality of spaced apart locations along an optical waveguide, the method including the steps of:

(i) transmitting a test signal onto the waveguide, the test signal being returned in a time distributed manner along the waveguide such that each spaced apart location has a return time associated therewith;

(ii) capturing the returned signal at a return time, the return time being chosen in dependence on the location from which information is to be acquired; and

(iii) processing the test signal captured at the chosen return time in order to acquire the introduced information.

11. A communication method as claimed in claim 10, wherein the step of processing the test signal captured at the chosen return time includes an operation involving the return signal captured at a time that is earlier that the chosen return time.

12. A communication method as claimed in claim 11, wherein the operation includes the subtraction of the return signal captured at earlier time from the return signal capture at the chosen time.

13. A communication method as claimed in claim 10, wherein the test signal is formed as a pair of signal copies, the signal copies of the pair being transmitted onto the waveguide with a temporal offset relative to one another.

14. A communication method in which information is introduced at a plurality of spaced apart locations along an optical waveguide, including the steps of:

(i) transmitting test signals onto the waveguide, components of the test signals being returned in a distributed manner along the waveguide;

(ii) receiving first component signals returned from beyond a first location at which information is introduced;

(iii) receiving second component signals returned from beyond a second location at which information is introduced, the second component signals being returned through the first location; and

, (iv) processing the second component signals using the first component signals to distinguish information introduced at the second location from information introduced at the first location.

15. A communication method as claimed in claim 14, wherein the step of processing the second component signals involves removing a contribution from the first component signals.

16. A communication method as claimed in claim 15, wherein a subtraction operation is performed to remove the contribution.