Swept frequency reflectometry using an optical signal with sinusoidal modulation
First Claim
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1. A method for characterizing an optical transmission path in a network with network traffic, the method comprising:
- modulating an optical signal with a pilot tone and outputting the modulated optical signal onto the optical transmission path;
sweeping the pilot tone across a frequency range;
detecting amplitudes and phases of the pilot tone along a forward path and a reflected path of the optical transmission path; and
characterizing the optical transmission path based on the detected amplitudes and phases.
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Abstract
An optical line terminal determines an approximate location of impairment in an optical transmission path (e.g., optical fiber) without disconnecting the optical line terminal from the optical transmission path. The optical line terminal generates pilot tones that are modulated on an optical signal and used to make reflection and dispersion measurements in a frequency domain reflectometry manner, thus providing for in-vivo diagnostic testing of the optical transmission path. The dispersion can be automatically corrected by using a dispersion compensator.
58 Citations
45 Claims
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1. A method for characterizing an optical transmission path in a network with network traffic, the method comprising:
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modulating an optical signal with a pilot tone and outputting the modulated optical signal onto the optical transmission path;
sweeping the pilot tone across a frequency range;
detecting amplitudes and phases of the pilot tone along a forward path and a reflected path of the optical transmission path; and
characterizing the optical transmission path based on the detected amplitudes and phases. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An apparatus for characterizing an optical transmission path in a network with network traffic, the apparatus comprising:
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a modulator that modulates an optical signal with a pilot tone and outputs the optical signal onto the optical transmission path carrying network traffic;
a sweep controller coupled to the modulator that causes the modulator to sweep the pilot tone across a frequency range;
a detection unit coupled to the optical transmission path and that detects amplitudes and phases of the pilot tone along a forward path and a reflected path of the optical transmission path; and
a processing unit responsive to the detection unit that characterizes the optical transmission path based on the detected amplitudes and phases. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. An apparatus for characterizing an optical transmission path in a network with network traffic, the apparatus comprising:
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means for modulating an optical signal with a pilot tone and for outputting the optical signal onto the optical transmission path carrying network traffic;
means for sweeping the pilot tone across a frequency range;
means for detecting amplitudes and phases of the pilot tone along a forward path and a reflected path of the optical transmission path; and
means for characterizing the optical transmission path based on the detected amplitudes and phases.
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38. A computer-readable medium having stored thereon sequences of instructions, the sequence of instructions, when executed by a digital processor, causing the process to perform the steps of:
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modulating an optical signal with a pilot tone, the optical signal being output onto an optical transmission path in a network with network traffic;
sweeping the pilot tone across a frequency range;
obtaining detected pilot tone amplitude and phase along a forward path and a reflected path of the optical transmission path; and
characterizing the optical transmission path based on the detected pilot tone amplitudes and phases.
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39. A data communications system for characterizing an optical transmission path in a network with network traffic, the system comprising:
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optical I/O providing data transfer across the optical transmission path; and
a swept frequency reflectometry subsystem including (i) a modulator to apply modulation to an optical signal across a frequency range in a swept manner, (ii) a detector coupled to the optical transmission path to detect the modulation along forward and reflected paths in the optical transmission path, and (iii) a processor coupled to the detector characterize the optical transmission path based on amplitudes and phases of the modulated optical signal in the forward and reflected paths. - View Dependent Claims (40, 41, 42, 43, 44, 45)
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Specification