# US 9,438,335 B2 · Optical fiber defect detection

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- Number: US 9,438,335 B2
- Document ID: US9438335B2
- Status: Granted
- Kind: B2
- Application number: 14/579,380
- Filed: 2014-12-22
- Published: 2015-07-02
- Granted: 2016-09-06
- Earliest claimed: 2013-12-26
- Assignees: Texas Instruments Incorporated
- Applicants: Texas Instruments Incorporated
- Inventors: Nagarajan Viswanathan
- Web page: https://patentgrep.com/patent/US9438335B2

## CPC

- H04B 10/071: using a reflected signal, e.g. using optical time domain reflectometers [OTDR]
- G01M 11/3109: {Reflectometers detecting the back-scattered light in the time-domain, e.g. OTDR}
- G01M 11/3118: {using coded light-pulse sequences}
- G01M 11/3127: {using multiple or wavelength variable input source}
- H04B: TRANSMISSION
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR

## Abstract

An optical data transmitter is operable to transmit data other than test data on an optical fiber at a first wavelength and an optical time domain reflectometer is operable to receive data from the optical fiber at the first wavelength and to use the received data at the first wavelength to determine whether a defect exists in the optical fiber.

## Claims

### Claim 1

An optical communication system, comprising:
an optical data transmitter operable to transmit data other than test data on an optical fiber at a first wavelength; and
an optical time domain reflectometer operable to receive data from the optical fiber at the first wavelength, to use the received data at the first wavelength to determine whether a defect exists in the optical fiber, to cross-correlate multiple sets of the received data and transmitted data, and to average the resulting cross-correlation values.

### Claim 2 (depends on 1)

The optical communication system of claim 1, where the optical data transmitter is operable to transmit data at a plurality of wavelengths in addition to the first wavelength.

### Claim 3 (depends on 1)

The optical communication system of claim 1, further comprising:
the optical time domain reflectometer further comprising a correlator operable to cross-correlate the received data and the transmitted data.

### Claim 4 (depends on 3)

The optical communication system of claim 3, where the cross-correlation is done in the frequency domain.

### Claim 5 (depends on 3)

The optical communication system of claim 3, further comprising:
the optical time domain reflectometer further operable to average the resulting cross-correlation values.

### Claim 6 (depends on 3)

The optical communication system of claim 3, further comprising:
an anti-aliasing filter that filters received data before cross-correlation.

### Claim 7 (depends on 3)

The optical communication system of claim 3, further comprising:
a decimator that reduces the amount of transmitted data being cross-correlated.

### Claim 8 (depends on 7)

The optical communication system of claim 7, further comprising:
an anti-aliasing filter that filters transmitted data before decimation.

### Claim 9 (depends on 1)

The optical communication system of claim 1, further comprising:
a controller operable to analyze information from the optical time domain
reflector to determine whether defects exist in the optical fiber.

### Claim 10

A method for defect detection in an optical fiber, comprising:
transmitting, by an optical data transmitter, data other than test data on an optical fiber at a first wavelength;
receiving, by an optical time domain reflectometer, data on the optical fiber at the first wavelength; and
cross-correlating, by a correlator, multiple sets of the received data and transmitted data; and
determining, by a controller, from the transmitted and received data, whether there is a defect in the optical fiber.

### Claim 11 (depends on 10)

The method of claim 10, further comprising:
analyzing, by the controller, the results of cross-correlation to determine whether there is a defect in the optical fiber.

### Claim 12 (depends on 11)

The method of claim 11, further comprising:
filtering, by an anti-aliasing filter, the received data before cross-correlating.

### Claim 13 (depends on 11)

The method of claim 11, further comprising:
filtering, by an anti-aliasing filter, the transmitted data before cross-correlating.

### Claim 14 (depends on 13)

The method of claim 13, further comprising:
reducing, by a decimator, the filtered transmitted data before cross-correlating.

### Claim 15

An optical communication system, comprising:
an optical data transmitter operable to transmit data on an optical fiber at a particular wavelength;
an optical time domain reflectometer operable to receive data from the optical fiber at the particular wavelength;
a correlator operable to cross-correlate the received data and the transmitted data; and
the optical communication system further operable to cross-correlate multiple sets of received data and transmitted data and to average the resulting cross-correlation values.

### Claim 16 (depends on 15)

The optical communication system of claim 15, further comprising:
a controller operable to analyze the average of the cross-correlations to determine whether there is a defect in the optical fiber.

### Claim 17 (depends on 15)

The optical communication system of claim 15, where the particular wavelength is also used to transmit data other than test data.

### Claim 18 (depends on 17)

The optical communication system of claim 17, where the particular wavelength is one of a plurality of wavelengths used to transmit data other than test data.

### Claim 19 (depends on 15)

The optical communication system of claim 15, further comprising:
an anti-aliasing filter that filters transmitted data before cross-correlation; and
a decimator that reduces the amount of transmitted data being cross-correlated.

### Claim 20 (depends on 15)

The optical communication system of claim 15, further comprising:
an anti-aliasing filter that filters received data before cross-correlation.