US-12625328-B2 - Activity detection in fiber optic network

US12625328B2US 12625328 B2US12625328 B2US 12625328B2US-12625328-B2

Abstract

In some embodiments, local intensity extrema at different wavelengths of a wavelength range reflected across a first cable of a first mode may be determined, the wavelength range being reflected by a second cable of a second mode different from the first mode. Reference locations for sampling windows of the wavelength range may be determined based on the local intensity extrema. A signal reflected across a cable of the first mode may be monitored based on the reference locations for the sampling windows. An activity related to the cable may be detected via a prediction model and based on the monitoring.

Inventors

Bobby Nakanelua
Stephen SOHN
Scott RYE

Assignees

CyberSecure Innovations, LLC

Dates

Publication Date: 20260512
Application Date: 20230802

Claims (20)

1 . A system for facilitating fiber optic cable monitoring, the system comprising: a remote termination unit comprising a housing and a multi-mode fiber optic cable coiled within the housing, the multi-mode fiber optic cable of the remote termination unit having six or more coils and being passively coupled to a single-mode fiber optic cable that is to be monitored; and one or more processors programmed with computer program instructions that, when executed, cause operations comprising: detecting calibration intensity peaks at different wavelengths of a wavelength range reflected across the single-mode fiber optic cable during a calibration phase, the wavelength range being reflected by the coils of the multi-mode fiber optic cable of the remote termination unit; determining, based on the calibration intensity peaks, reference locations for sampling windows of the wavelength range such that (i) each window of the sampling windows comprises a corresponding wavelength of an intensity peak of the calibration intensity peaks, (ii) each window of the sampling windows is a sampling of a different number of wavelengths than another window of the sampling windows, and (iii) the sampling windows collectively do not comprise other wavelengths of the wavelength range between respective ones of the sampling windows of the wavelength range; monitoring, based on the reference locations for the sampling windows, light reflected across the single-mode fiber optic cable during an operation phase without monitoring the other wavelengths of the wavelength range, the light being reflected by the coils of the multi-mode fiber optic cable of the remote termination unit; and detecting, via a prediction model, based on the monitoring, a disturbance activity related to the single-mode fiber optic cable.
2 . The system of claim 1 , further comprising a fiber optic controller configured to transmit a laser signal across the single-mode fiber optic cable to the remote termination unit, wherein monitoring the light reflected across the single-mode fiber optic cable comprises: detecting, via the fiber optic controller, the light reflected across the single-mode fiber optic cable; and filtering, based on the reference locations for the sampling windows, the detected light to obtain filtered light data that excludes wavelengths outside of the sampling windows; and wherein detecting the disturbance activity comprises inputting the filtered light data into the prediction model to obtain a prediction indicating the disturbance activity.
3 . The system of claim 1 , wherein determining the reference locations comprises determining the reference locations for the sampling windows based on the calibration intensity peaks and a spacing threshold such that each sampling window of the sampling windows is separated by at least the spacing threshold from a next sampling window of the sampling windows closest to the sampling window.
4 . The system of claim 1 , wherein the remote termination unit is passively coupled to the single-mode fiber optic cable via an angled physical contact (APC) connector.
5 . A method comprising: detecting local intensity extrema at different wavelengths of a wavelength range reflected across a first cable of a first mode, the wavelength range being reflected by a second cable of a second mode; determining, based on the local intensity extrema, reference locations for sampling windows of the wavelength range such that (i) each window of the sampling windows comprises a corresponding wavelength of a local extremum of the local intensity extrema and (ii) the sampling windows collectively do not comprise other wavelengths of the wavelength range between at least two of the sampling windows of the wavelength range; monitoring, based on the reference locations for the sampling windows, a signal reflected across a cable of the first mode; and detecting, via a prediction model, based on the monitoring, an activity related to the cable.
6 . The method of claim 5 , wherein the first cable of the first mode comprises a single-mode cable, and the second cable of the second mode comprises a multi-mode cable of a remote termination unit, the multi-mode cable of the remote termination unit being passively connected to the single-mode cable.
7 . The method of claim 5 , wherein the first cable of the first mode has a first cable core size, and the second cable of the second mode has a second cable core size different from the first cable core size, the second cable of the second mode being (i) passively connected to the first cable of the first mode and (ii) coiled within a remote termination unit.
8 . The method of claim 5 , wherein the first cable of the first mode has a first cable material makeup, and the second cable of the second mode has a second cable material makeup different from the first cable material makeup, the second cable of the second mode being (i) passively connected to the first cable of the first mode and (ii) coiled within a remote termination unit.
9 . The method of claim 5 , wherein: monitoring the signal reflected across the cable of the first mode comprises extracting, based on the reference locations for the sampling windows, a portion of the signal that falls within the sampling windows; and detecting the activity related to the cable comprises inputting the extracted portion of the signal to the prediction model to obtain a prediction indicating the activity.
10 . The method of claim 5 , wherein determining the reference locations comprises determining the reference locations for the sampling windows based on the local intensity extrema and a spacing threshold such that each sampling window of the sampling windows is separated by at least the spacing threshold from a next sampling window of the sampling windows closest to the sampling window.
11 . The method of claim 5 , wherein determining, based on the local intensity extrema, reference locations for sampling windows of the wavelength range comprises: for each local intensity extremum of the local intensity extrema, determining the corresponding wavelength of the local intensity extremum; and determining the reference locations of a sampling window by positioning the corresponding wavelength at a center of the sampling window.
12 . The method of claim 5 , wherein each window of the sampling windows is a sampling of a different number of wavelengths than at least one other window of the sampling windows.
13 . The method of claim 5 , wherein: monitoring the signal reflected across the cable of the first mode comprises extracting, based on the reference locations for the sampling windows, portions of the signal that respectively fall within the sampling windows; and detecting the activity comprises: scaling, based on one or more window size criteria, the portions of the signal such that the scaled portions are more similar to one another with respect to the one or more window size criteria than before the scaling; and detecting, via the prediction model, based on the scaled portions of the signal, the activity related to the cable.
14 . The method of claim 5 , wherein: monitoring the signal reflected across the cable of the first mode comprises extracting, based on the reference locations for the sampling windows, portions of the signal that respectively fall within the sampling windows; and detecting the activity comprises: for each portion of the portions of the signal that respectively fall within the sampling windows, determining percentage differences between wavelength intensities within the portion of the signal and baseline wavelength intensities for the sampling window corresponding to the portion of the signal; detecting, via the prediction model, based on the percentage differences, the activity related to the cable.
15 . A non-transitory, computer-readable media storing instructions that, when executed by one or more processors, cause operations comprising: detecting local characteristic extrema at different wavelengths of a wavelength range reflected across a first cable of a first mode; determining, based on the local characteristic extrema, reference locations for sampling windows of the wavelength range such that (i) each window of the sampling windows comprises a corresponding wavelength of a local characteristic extremum of the local characteristic extrema and (ii) the sampling windows collectively do not comprise other wavelengths of the wavelength range between at least two of the sampling windows of the wavelength range; monitoring, based on the reference locations for the sampling windows, a signal reflected across a cable of the first mode; and detecting, via a prediction model, based on the monitoring, an activity related to the cable.
16 . The media of claim 15 , wherein the wavelength range is reflected by a second cable of a second mode different from the first mode.
17 . The media of claim 15 , wherein the cable being monitored is different from the first cable.
18 . The media of claim 15 , wherein determining the reference locations comprises determining the reference locations for the sampling windows based on the local characteristic extrema and a spacing threshold such that each sampling window of the sampling windows is separated by at least the spacing threshold from a next sampling window of the sampling windows closest to the sampling window.
19 . The media of claim 15 , wherein: monitoring the signal reflected across the cable of the first mode comprises extracting, based on the reference locations for the sampling windows, a portion of the signal that falls within the sampling windows; and detecting the activity related to the cable comprises inputting the extracted portion of the signal to the prediction model to obtain a prediction indicating the activity.
20 . The media of claim 15 , wherein: monitoring the signal reflected across the cable of the first mode comprises extracting, based on the reference locations for the sampling windows, portions of the signal that respectively fall within the sampling windows; and detecting the activity comprises: scaling, based on one or more window size criteria, the portions of the signal such that the scaled portions are more similar to one another with respect to the one or more window size criteria than before the scaling; and detecting, via the prediction model, based on the scaled portions of the signal, the activity related to the cable.

Description

SUMMARY Methods and systems are described herein for improvements related to detection of activities based on monitoring cable signals (e.g., selected portions of light reflected by a remote termination unit and across a fiber optic cable). With respect to existing light-based activity detection systems, for example, activity detection is generally performed by monitoring electrical signals from components such as photodiodes (e.g., the detector component) to measure the intensity of a light source (e.g., a laser source) and output an electronic signal related to the measurement. In the context of intrusion detection, such existing systems will typically measure laser signal strength, Fresnel reflections, and Rayleigh backscatter either directly from the signal or from a reflected laser signal. Such existing systems, however, typically require specialized and complex hardware (e.g., Fabry-Pérot (FP) lasers, precise pulse generators, etc.,) to do so that are costly or introduce other constraints (e.g., distributed acoustic sensing has limited dynamic range). To address one or more of the foregoing issues, in some embodiments, a remote termination unit (RTU) including a multi-mode fiber optic cable may be employed by passively coupling the RTU to a fiber optic cable to be monitored (e.g., at an end of the fiber optic cable). As an example, as a laser signal travels through the multi-mode cable of the RTU, the multi-mode cable causes dispersion of the laser signal, and much of this dispersed laser signal is reflected back from the multi-mode cable through the monitored cable. In one use case, an interrogator (e.g., fiber optic interrogator, a fiber optic controller, etc.) may detect the reflected laser. In this way, for example, due to the dispersion caused by the multi-mode cable, activity directed at or in a vicinity of the fiber optic cable causes a detectable change in the detected laser without necessarily requiring one or more specialized and complex hardware (e.g., without requiring the use of a distributed system of Fiber Bragg grating (FBG) sensors, FP lasers, precise pulse generators, etc.). In some embodiments, selected portions of a wavelength range of the reflected laser, instead of the entire wavelength range detected by the interrogator, may be monitored. As an example, during a calibration phase, calibration intensity peaks may be detected at different wavelengths of a wavelength range reflected by the multi-mode fiber optic cable of the RTU and across the single-mode fiber optic cable. Based on the calibration intensity peaks, reference locations for sampling windows of the wavelength range may be determined. Each window of the sampling windows may include a corresponding wavelength of an intensity peak of the calibration intensity peaks. Additionally, or alternatively, the sampling windows collectively may not include other wavelengths of the wavelength range between respective ones of the sampling windows of the wavelength range. In some embodiments, at least two windows of the sampling windows may span different numbers of wavelengths than each other. In some embodiments, monitoring for one or more activities of the fiber optic cable may be performed by monitoring, based on the reference locations for the sampling windows, light reflected across the fiber optic cable during one or more time periods of an operation phase without monitoring the other wavelengths of the wavelength range during such time periods, thereby reducing computation resource usage or processing time (and, thus, increasing the efficiency of the system). Based on the monitoring, the activities (e.g., a disturbance event related to the fiber optic cable) may be detected via a prediction model. Spectral features of reflected light may depend on or relate to characteristics of components in a light path that the light traverses. Such components may include, for example, a specific RTU (e.g., having a multi-mode fiber optic cable with a specific core size, material, or length), a specific fiber optic cable to be monitored, a specific fiber interrogator, or other components. In some embodiments, instead of a dedicated prediction model for each combination of these components of such a monitoring system, a light signal reflected by an RTU and detected by a fiber interrogator may be processed such that the processed signal may be analyzed using a common prediction model (e.g., by scaling or performing other normalization techniques on the reflected light signal), thereby increasing the versatility of the prediction model of the system. Additional, or alternatively, parameters employed in monitoring may be adjusted based on specific applications (e.g., specific fiber optic cables to be monitored, specific RTUs, or fiber interrogators to be used), feedback from prior monitoring, user instructions, or other information, thereby allowing adaptation or improvement of the system. Various other aspects, features, and advantages of the