In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.

In some examples, fiber optic cable location may include transmitting a coherent laser pulse into a device under test (DUT). Based on an analysis of reflected light resulting from the transmitted coherent laser pulse, changes in intensity of the reflected light caused by a plurality of signals directed towards the DUT may be determined. Further, based on the changes in intensity of the reflected light, a location of the DUT may be determined.

A time domain reflectometry measurement apparatus and method is provided. Measurement data of a time domain reflectometry measurement are analyzed with respect to previously acquired empirical measurement data of error-free or faulty devices with known failures. In this way, failures can be identified in the device under test without the need of opening the device.

Brillouin fiber sensors can provide distributed measurements of parameters of interest over long distances in a fiber by measuring the Brillouin frequency shift as a function of position along the fiber. The Brillouin frequency shift may be determined, to within a small fraction of the Brillouin linewidth, by establishing a series of lasing modes that experience Brillouin amplification at discrete spatial locations in a test fiber. A linewidth narrowing and high intensity associated with the lasing transition enable precise measurements of the lasing frequency associated with each of the lasing modes. The Brillouin frequency may be determined based on the lasing frequency.

An improved technique for acoustic sensing involves, in one embodiment, launching into a medium, a plurality of groups of pulse-modulated electromagnetic-waves. The frequency of electromagnetic waves in a pulse within a group differs from the frequency of the electromagnetic waves in another pulse within the group. The energy scattered by the medium is detected and, in one embodiment, may be used to determine a characteristic of the environment of the medium. For example, if the medium is a buried optical fiber into which light pulses have been launched in accordance with the invention, the presence of acoustic waves within the region of the buried fiber can be detected.

In some examples, QR code based test data embedding and transmission may include obtaining, by a test data analyzer that is executed by at least one hardware processor, test data based on operation of a test device to measure a parameter associated with an optical fiber. Based on an analysis of the test data, a report that includes the test data may be generated. A quick response (QR) code generator that is executed by the at least one hardware processor may compress the report that includes the test data to generate a compressed report. The QR code generator may generate, based on an analysis of the compressed report, a QR code that includes the compressed report. A display generator that is executed by the at least one hardware processor may generate a display of the QR code that includes the compressed report.

A zeroing method and zeroing device for an optical time-domain reflectometer (OTDR) are disclosed. The zeroing method includes: before starting the optical time-domain reflectometer, when a laser device is in an off state, sending a zeroing signal; and performing zeroing processing according to the zeroing signal. In the embodiments of the present invention, the feedback zeroing can be performed on a receiving circuit by utilizing the idle time prior to a test or during the test, thus the influence of an offset voltage is reduced, and a problem of operational-amplifier zero drift also can be solved in the meantime, which improves a detectability of the OTDR, and overcomes a disadvantage that a manual zeroing method is not intelligent and a measured waveform introduced in an automatic zeroing method is bad.

Methods of measuring an anomaly, any induced change in physical parameters such as strain, temperature, and so forth, in an optical fiber. One method may include launching a plurality of probe pulses from a probe source; recording a Brillouin scattering spectrum from a plurality of reflection signals generated in the optical fiber, responsive to the plurality of probe pulses; determining a relative motion between the optical fiber and the anomaly during the recording the Brillouin back-scattering spectrum; and dynamically adjusting the Brillouin back-scattering spectrum according to the relative motion, or performing an adjustment of the Brillouin back-scattering spectrum after acquisition of the Brillouin back-scattering spectrum.

This invention relates to a fiber optic fiber testing device presented in an app that compares three fiber link parameters against a table of specifications required in order for that fiber to transmit data at a particular speed. The invention presents a convenient ‘Pass’ or ‘Fail’ result for each parameter tested that immediately verifies whether the fiber being tested will meet the minimum basic criteria for transmission of data at a particular bandwidth speed, in accordance with that particular fiber manufacturer's specifications.

An improved technique for acoustic sensing involves, in one embodiment, launching into a medium, a plurality of groups of pulse-modulated electromagnetic-waves. The frequency of electromagnetic waves in a pulse within a group differs from the frequency of the electromagnetic waves in another pulse within the group. The energy scattered by the medium is detected and, in one embodiment, may be used to determine a characteristic of the environment of the medium. For example, if the medium is a buried optical fiber into which light pulses have been launched in accordance with the invention, the presence of acoustic waves within the region of the buried fiber can be detected.