Method for monitoring wavelength-division multiplexed signal

• US 8,111,988 B1
• Filed: 06/10/2008
• Issued: 02/07/2012
• Est. Priority Date: 06/10/2008
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Schantz, Howard J., Uhlhorn, Brian L.
• Primary Examiner(s): Vanderpuye, Kenneth N
• Assistant Examiner(s): Wolf, Darren E
• Application Number:
  US12/136,249
• Time in Patent Office: 1,337 Days
• Field of Search: None
• US Class Current: 398/34
• CPC Class Codes: H04B 10/0775 Performance monitoring and measurement of transmission parameters
• CPC Class Codes: H04B 2210/078 using a separate wavelength

Abstract

A method for monitoring wavelength-division multiplexed (WDM) signal for detecting signal drift of objective signals, including generation of one or more objective signals and a guard signal. The guard signal has a wavelength that is within a range defined by a guard channel. The first and second objective signals and the guard signal are wavelength-division multiplexed to generate a wavelength-division multiplexed signal. The first objective signal, the second objective signal, and the guard signal are assigned to a first multiplexed objective channel, a second multiplexed objective channel, and a multiplexed guard channel, respectively. The wavelength-division multiplexed signal is received by a monitor and then the error rate of the multiplexed guard channel is determined.

Claims

1. A method for monitoring a wavelength-division multiplexed signal, comprising:

generating a first objective signal including a first objective wavelength λ

_o1,

generating a second objective signal including a second objective wavelength λ

_o2,

selecting a guard wavelength λ

_g according to a channel hopping protocol wherein the guard wavelength λ

_g varies between λ

_o1 and λ

_o2, and generating a guard signal including the guard wavelength λ

_g that is between λ

_o1 and λ

_o2;

generating a wavelength-division multiplexed signal by wavelength-division multiplexing the first objective signal, the second objective signal, and the guard signal,

wherein the wavelength-division multiplexed signal includes;

a first multiplexed objective channel,

a second multiplexed objective channel, and

a multiplexed mud channel having a range of wavelengths between λ

_o1 and λ

_o2;

receiving the wavelength-division multiplexed signal by a monitor; and

determining an error of the multiplexed guard channel by comparing the multiplexed guard channel to the guard signal.

2. The method for monitoring a wavelength-division multiplexed signal according to claim 1, wherein the channel hopping protocol includes selecting the guard wavelength λ

_g from a predetermined set of guard channel wavelengths λ

₁ to λ

_N (N≧

2).

3. The method for monitoring a wavelength-division multiplexed signal according to claim 1, wherein the channel hopping protocol includes selecting the guard wavelength λ

_g randomly from a predetermined set of guard channel wavelengths λ

₁ to λ

_N (N≧

2).

4. The method for monitoring a wavelength-division multiplexed signal according to claim 1, wherein the channel hopping protocol includes time variably selecting the guard wavelength λ

_g.

5. A system for monitoring a wavelength-division multiplexed signal, comprising:

a first node that generates a first objective signal for carrying data;

a second node that generates a second objective signal for carrying data;

a guard channel monitor that generates a guard signal having a predetermined wavelength;

a central hub configured to receive the first objective signal, the second objective signal, and the guard signal, and configured to wavelength-division multiplex the first objective signal, the second objective signal, and the guard signal to generate a multiplexed signal, and configured to send the multiplexed signal to the guard channel monitor, the multiplexed signal has a range of wavelengths that includes the predetermined wavelength; and

the guard channel monitor configured to compare the guard signal to the multiplexed signal at the predetermined wavelength.

6. The system for monitoring a wavelength-division multiplexed signal according to claim 5, wherein the central hub is a star coupler.

7. The system for monitoring a wavelength-division multiplexed signal according to claim 6, wherein the star coupler is a passive star coupler.

8. A method for monitoring a wavelength-division multiplexed signal, comprising:

generating from a first node, a first objective signal for carrying data;

generating from a second node, a second objective signal for carrying data;

generating from a guard channel monitor, a guard signal having a predetermined wavelength;

receiving by a central hub, the first objective signal, the second objective signal, and the guard signal, and generating a multiplexed signal by wavelength-division multiplexing the first objective signal, the second objective signal, and the guard signal, and sending the multiplexed signal to the guard channel monitor, the multiplexed signal has a range of wavelengths that includes the predetermined wavelength; and

the guard channel monitor receiving the multiplexed signal, and comparing the guard signal to the multiplexed signal at the predetermined wavelength.

9. The method according to claim 8, further comprising:

determining a direction of a signal drift of the first objective signal by comparing the guard signal to the multiplexed signal at the predetermined wavelength.