Alarm System for an Optical Network

• US 20160218800A1
• Filed: 12/31/2013
• Published: 07/28/2016
• Est. Priority Date: 12/31/2012
• Status: Active Grant

• Current Assignee: Network Integrity Systems, Inc.
• Original Assignee: Network Integrity Systems, Inc.
• Inventors: Murphy, Cary R., Goertzen, Daniel, Bridges, Mark K.
• Granted Patent: US 9,954,609 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02B 6/00 Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
• CPC Class Codes: H04B 10/00 Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
• CPC Class Codes: H04B 10/071 using a reflected signal, e.g. using optical time domain reflectometers [OTDR]
• CPC Class Codes: H04B 10/0793 Network aspects, e.g. central monitoring of transmission parameters
• CPC Class Codes: H04B 10/0795 Performance monitoring; Measurement of transmission parameters
• CPC Class Codes: H04B 10/27 Arrangements for networking
• CPC Class Codes: H04B 10/85 Protection from unauthorised access, e.g. eavesdrop protection
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04L 41/06 Management of faults, events, alarms or notifications
• CPC Class Codes: H04L 43/0811 by checking connectivity
• CPC Class Codes: H04L 43/10 Active monitoring, e.g. heartbeat, ping or trace-route

Abstract

A method is provided for detecting intrusion into optical fibers of a Passive Optical Network (PON) of the type which includes a multiplexing system at the head end for separating a data signal output at the head end to the plurality of fibers for supply to user end terminals and a data transmission system at each of the user end terminals for entering onto the fiber data as an optical signal. The method includes providing a monitor system having a transmitter at the head end and a monitor signal analysis system for analyzing changes in the optical monitor signal after transmission along the fiber for detecting an intrusion event. A monitor signal analysis system is provided at one or more user end terminals for detection and conversion of data from the analysis into a digital signal which is then transmitted from the user end terminals back to the head end using the data transmission system through the PON system or separately from the PON system.

Claims

1. A method for detecting intrusion into at least one optical fiber of an optical fiber cable of an Optical Network where the network comprises:

a plurality of fibers each having a first end and a second end;

the second end of at least some of the fibers being connected to respective ones of a plurality of user end terminals;

a multiplexing system for separating a data signal output to the plurality of fibers for supply to the user end terminals;

a data transmission system at each of the user end terminals for transmitting data as an optical signal;

the method comprising;

providing a monitor system having a transmitter for a monitor signal to be applied onto at least one of the plurality of fibers, the monitor system having a monitor signal analysis system for analyzing changes in the optical monitor signal after transmission along the fiber or fibers for detecting an intrusion event;

providing at at least one of said end user terminals a monitor signal receiver system for detection and conversion of data from the analysis into a digital signal;

and transmitting the digital signal from said at least one of the user end terminals back to the monitor system using the data transmission system.

2. The method according to claim 1 wherein each of a plurality of the end user terminals includes a receiver for detection and conversion to a digital signal after transmission along the respective fiber.

3. The method according to claim 1 wherein the signal processing system of the monitor system is located at the head end and includes an alarm reporting system.

4. The method according to claim 1 wherein the data transmission systems of the end user terminals communicate the data signal using the data network.

5. The method according to claim 1 wherein the data transmission systems of the end user terminals communicate the data signal separately from the network.

6. The method according to claim 1 wherein there is provided a multiplexer for multiplexing the data signals and the monitoring signals onto said fibers.

7. The method according to claim 1 wherein the transmitter is arranged to transmit split signals which are time division multiplexed (TDM) onto said fibers so that the multiplexed signal is received by a single photodetector/ADC at the respective receiver.

8. The method according to claim 6 wherein said signals are demultiplexed at the respective receiver.

9. The method according to claim 6 wherein said signals are demultiplexed at said signal analysis system.

10. The method according to claim 6 wherein the monitor signal is an out of band monitor wavelength.

11. The method according to claim 6 wherein the monitor signal is a portion of the data signal.

12. The method according to claim 6 wherein the monitor signal is an unused wavelength and is multiplexed using WDM.

13. The method according to claim 6 wherein the signal output is an injected special monitor wavelength within WDM window.

14. The method according to claim 6 wherein the signal output is a special monitor wavelength outside of data wavelengths using coupler such as, but not limited to wideband or WDM.

15. The method according to claim 6 including providing an insensitive lead-in fiber leading to the multiplexer.

16. The method according to claim 1 wherein the PON signal and the monitor signal are located in an approved hardened conveyance so as to meet federal approval for alarmed carrier PDS.

17. The method according to claim 1 wherein the PON signal and protection signal are multiplexed onto a single fiber using WDM.

18. The method according to claim 1 wherein the cables to the end users are all fiber cables.

19. The method according to claim 1 wherein the cables to the end users are hybrid fiber/electrical

20. The method according to claim 1 wherein the monitor system acts by providing at least one sensor arrangement for receiving a light signal transmitted through the fibers, detecting a series of received light signals which have been transmitted along the fibers to be monitored;

comparing at least some of the received light signals relative to data obtained from previously received ones of the received light signals to detect changes in the received light signals relative to the previously received light signals; and

analyzing the changes to determine any changes which are indicative of manipulation of the optical fiber causing movement of a portion thereof along the length thereof.