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762 results about "Optical time-domain reflectometer" patented technology
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An optical time-domain reflectometer (OTDR) is an optoelectronic instrument used to characterize an optical fiber. An OTDR is the optical equivalent of an electronic time domain reflectometer. It injects a series of optical pulses into the fiber under test and extracts, from the same end of the fiber, light that is scattered (Rayleigh backscatter) or reflected back from points along the fiber. The scattered or reflected light that is gathered back is used to characterize the optical fiber. This is equivalent to the way that an electronic time-domain meter measures reflections caused by changes in the impedance of the cable under test. The strength of the return pulses is measured and integrated as a function of time, and plotted as a function of fiber length.
Network profiling system having physical layer test system
A network profiling system is provided including providing a base station tester having both a spectrum analyzer and a vector network analyzer, inserting an optical time domain reflectometer system in the base station tester, and operating a touch screen display of the base station tester for testing a cellular base station having both a non-optical portion and a backhaul with an optical fiber. The operating of the touch screen display further includes testing the non-optical portion with the vector network analyzer, the spectrum analyzer, or a combination thereof. The operating of the touch screen display also includes testing the backhaul having the optical fiber with the optical time domain reflectometer system, and analyzing test data from the testing the non-optical portion with the backhaul.
Owner:SUNRISE TELECOM
Passive optical network (PON) in-band optical time domain reflectometer (OTDR)
ActiveUS20110013904A1Material analysis by optical meansTransmission monitoringSignal onNetwork Communication Protocols
An in-band OTDR uses a network's communication protocols to perform OTDR testing on a link. Because the OTDR signal (probe pulse) is handled like a data signal, the time required for OTDR testing is typically about the same as the time required for other global network events, and is not considered an interruption of service to users. A network equipment includes an optical time domain reflectometry (OTDR) transmitter and receiver, each operationally connected to a link to transmit and receive, respectively, an OTDR signal. When an OTDR is to be performed, a network device operationally connected to the link actuates the OTDR transmitter to transmit the OTDR signal on the link during a determined test time based on a communications protocol of the link, during which data signals are not transmitted to the network equipment. A processing system processes the OTDR signal to provide OTDR test results.
Owner:MICROSEMI ISRAEL STORAGE SOLUTIONS LTD
Optical time domain reflectometer which measures an optical fiber with different wavelengths according to an order and collectively displays waveform data and a list of events for each waveform in the same screen
InactiveUS6611322B1Easy to operateEasy to masterVehicle testingMaterial analysis by optical meansTime domainPhotodetector
A light pulse generator is connected with one end of an optical fiber which selectively emits light pulses of a plurality of wavelengths to the optical fiber. A photodetector outputs a signal corresponding to the strength of the light reflected from the optical fiber. A storage unit stores the signal output from the photodetector for each wavelength. A processor determines the position and characteristic of an event based on the waveform data for each wavelength stored in the storage device. A display device has first and second display areas. A display controller allows the first display area to display the waveform data for each wavelength stored in the storage unit in a discriminable manner, and allows the second display area to display a list of positions and characteristics of events for each wavelength determined by the processor.
Owner:ANRITSU CORP
Bidirectional optical module and optical time domain reflectometer
ActiveUS7853104B2Increase optical powerHigh sensitivityReflectometers dealing with polarizationMaterial analysis by optical meansTime domainOptical Module
A bidirectional optical module according to the present invention emits light to an optical fiber and allows returning light from the optical fiber to enter and includes a plurality of light emitting elements that emit light to enter the optical fiber, a light receiving element that receives light having exited the optical fiber, and a non-reciprocal unit for making an optical path in a forward direction from the light emitting element to the optical fiber and an optical path in a backward direction from the optical fiber to the light emitting element different. Then, polarization planes of light incident on the optical fiber after being emitted from the plurality of light emitting elements are mutually orthogonal, and the non-reciprocal unit emits returning light of light emitted from the plurality of light emitting elements from the optical fiber toward the light receiving element to one light receiving element.
Owner:YOKOGAWA ELECTRIC CORP +1
Measurement of large strains in ropes using plastic optical fibers
InactiveUS20050226584A1Minimal intrusionPrevent slippingControlOptical rangefindersTime domainEngineering
A method for the direct measurement of large strains in ropes in situ using a plastic optical fiber, for example, perfluorocarbon or polymethyl methacrylate and Optical Time-Domain Reflectometer or other light time-of-flight measurement instrumentation. Protective sheaths and guides are incorporated to protect the plastic optical fiber. In one embodiment, a small rope is braided around the plastic optical fiber to impose lateral compressive forces to restrain the plastic optical fiber from slipping and thus experience the same strain as the rope. Methods are described for making reflective interfaces along the length of the plastic optical fiber and to provide the capability to measure strain within discrete segments of the rope. Interpretation of the data allows one to calculate the accumulated strain at any point in time and to determine if the rope has experienced local damage.
Owner:WILLIAMS JERRY GENE +2
Polarization-OTDR for measuring characteristics of optical fibers
InactiveUS6724469B2Reflectometers dealing with polarizationMaterial analysis by optical meansStatistical analysisOptical time-domain reflectometer
In a method of polarization optical time-domain reflectometer (P-OTDR) for measuring a parameter of an optical transmission path, for example an optical fiber, by transmitting pulses of light into the path and measuring the state of polarization of backscattered light against distance, statistical analysis of the degree of polarization (DOP) of the backscattered signal is used to detect sections of an optical transmission path for which mode-coupling behaviour (long h) leads to high PMD. Preferably, successive DOP measurement are taken with different state of polarization, SOP, for the P-OTDR light source.
Owner:EXFO ELECTRO OPTICAL ENG
Dynamic performance monitoring of long slender structures using optical fiber strain sensors
A method is described using optical fiber technology to measure the vibration characteristics of long slender structures subjected to dynamic disturbances imposed by water or wind generated loads. The method is based on making bending strain measurements at selected locations along the length of long slender structures such as marine risers or large ropes using fiber optics technology including Optical Time Domain Reflectometry and Bragg diffraction gratings. Engineering interpretation of information obtained from bending strains determines the vibration characteristics including frequency, amplitude, and wave length. Maximum bending strain measurements assess pending structural damage. One application is measurement of vortex induced vibrations (VIV) response of marine risers. The fiber optics based method is also applicable to the measurement of the bending characteristics of spoolable pipe using plastic optical fibers which can be interpreted to assess the pipe structural integrity and to prevent lock-up during deployment into a small diameter annulus.
Owner:WILLIAMS JERRY GENE
Method and apparatus for optical time domain reflectometry (OTDR) analysis
InactiveUS6674518B1Amplifier modifications to reduce noise influenceDigital computer detailsFiberTime domain
The present invention is directed to a method and apparatus for testing a fiber-optic cable. An Optical Time Domain Reflectometer (OTDR) is presented. Test signals are generated from the OTDR and received by the OTDR for processing. The received test signals are sampled and analyzed. The received test signals include reflectance spikes and a slope. A first-order derivative is taken of the received signal. The first-order derivative is then filtered to remove the reflectance spikes and the slope. Discontinuities in the filtered first-order derivative denote a fault in the fiber-optic cable.
Owner:AMERICAN TELEPHONE & TELEGRAPH CO
Testing of Optical Cable Using Optical Time Domain Reflectometry
ActiveUS20120176607A1Material analysis by optical meansReflectometers detecting back-scattered light in time-domainTime domainEngineering
Methods for testing optical equipment are disclosed. One method includes connecting an optical time domain reflectometer to optical equipment to be tested, the optical equipment including at least one optical connector. The method includes injecting an optical signal onto the optical equipment from the optical time domain reflectometer, and observing an amount of reflected light at the connector. Based on the observed reflected light, an amount of loss attributable to the optical equipment is determined.
Owner:BISON PATENT LICENSING LLC
Passive optical network optical time-domain reflectometry
InactiveUS20080031624A1Material analysis by optical meansTime-division multiplexTime-domain reflectometerOptical test
Optical Time-Domain Reflectometer (OTDR) troubleshooting of a passive optical network (PON) can be enhanced by deploying cascaded splitters, at least some of which have multiple inputs. That is, at least some of the splitters in the PON have not only a first input coupleable to the optical line terminator (OLT) or output of another splitter but also a second input directly coupleable to an Optical Time-Domain Reflectometer (OTDR). Optical time-delay reflectometry can be performed upon a selected portion or segment of the PON by selecting a splitter and transmitting an optical test signal from the OTDR directly to the input of the selected splitter and analyzing the reflected signal.
Owner:ALCATEL LUCENT SAS
BOTDR (Brillouin Optical Time Domain Reflectometer) for calibrating optical power of reference light and calibrating method thereof
InactiveCN101839698AAccurate measurementHigh measurement accuracyThermometers using physical/chemical changesThermometer testing/calibrationTime domainOptical power
Owner:NANJING UNIV
Optical time domain reflectometer
ActiveUS7880868B2Material analysis by optical meansReflectometers detecting back-scattered light in time-domainTime domainOptical time-domain reflectometer
An improvement is added to an optical time domain reflectometer for emitting pulsed light of invisible light to a measured optical fiber, receiving return light of the pulsed light by a light detection section, measuring the measured optical fiber, and emitting visible light for visible inspection of a fault point of the measured optical fiber to the measured optical fiber. The optical time domain reflectometer includes an incidence-emission port for emitting the invisible light and the visible light to the measured optical fiber and an output judgment section for judging that a communication light exists in the measured optical fiber based on the light power of the light detection section receiving light incident through the incidence-emission port in a state in which the pulsed light of the invisible light is not emitted.
Owner:YOKOGAWA ELECTRIC CORP
Multi-point localizable distribution-type optical-fiber vibration sensor based on polarization-state differential detection
InactiveCN102809421AHigh detection sensitivityHigh positioning accuracySubsonic/sonic/ultrasonic wave measurementUsing wave/particle radiation meansTime domainPhotovoltaic detectors
The invention discloses a distribution-type optical-fiber vibration sensor which is based on polarization-state differential detection and can localize multiple points of vibration sources, and the sensor is characterized in that on the basis of the traditional optical time domain reflectometer, a polarization beam splitter is used for detecting a polarization state of backward scattered light in sensing optical fibers, two beams of orthogonal polarization light which is outputted by the polarization beam splitter are respectively photoelectrically converted by two photoelectric detectors, then differential operation and amplification processing is conducted for two detected signals, the signals are sampled by an analog / digital (A / D) converter, and the sample is sent into an embedded computer to be data analyzed and computed so as to realize the precise localization of the vibration sources which are distributed along the axial direction of the optical fibers. Due to adopting the multi-point localizable distribution-type optical-fiber vibration sensor, the simultaneous localization of multi-point weak vibration sources which are distributed along the axial direction of the optical fibers can be realized. The multi-point localizable distribution-type optical-fiber vibration sensor is simple and reliable, easy to implement and maintain and suitable for the detection and precise localization of the weak vibration signal sensed by the long-distance laid optical fibers.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA
Optical frequency division multiplexing phase-sensitive optical time domain reflectometer
InactiveCN102645268AHigh sensitivityImprove dynamic rangeSubsonic/sonic/ultrasonic wave measurementUsing wave/particle radiation meansLine widthLow-pass filter
The invention discloses an optical frequency division multiplexing phase-sensitive optical time domain reflectometer which comprises a narrow line width laser, an optical fiber coupler, a phase modulator, a scrambler, an erbium-doped optical fiber amplifier, an acoustic optical modulator, an optical fiber circulator, a signal generator module, a trigger source, a double balance detector, a low pass filter, a data acquisition card, a computer and a long-distance sensing optical fiber. According to the optical frequency division multiplexing phase-sensitive optical time domain reflectometer, the fundamental contradictions between the measuring distance and sampling rate in a distributed sensing system can be solved, and remoter or higher-frequency vibration is detected; and moreover, due to amplitude and phase information, the characteristics of a vibration source are judged at the first time, and the early warning can be provided immediately.
Owner:SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
Chaotic optical time domain reflectometer method and apparatus
ActiveUS20100290035A1Avoid disadvantagesHigh resolutionAmplifier modifications to reduce noise influenceDigital computer detailsFiberFiber coupler
In a method and a corresponding apparatus for performing chaotic optical time domain reflectometer, the chaotic laser signal, generated by the chaotic laser transmitter, is split into probe signal I and reference signal II by a fiber coupler. Through an optical circulator, the probe signal I is launched into the test fiber and the echo light is converted into electrical signal by a photodetector and digitalized by an A / D converter. The reference signal II is converted into electrical signal by a photodetector and digitalized by another A / D converter. Two digital signals received from two A / D converters are correlated in a signal processing device to locate the exact position of faults in fibers. The result output is then displayed on a display device. This invention was developed to overcome the tradeoff between resolution and dynamic range of the pulse-based OTDR. This method can improve the dynamic range and spatial resolution significantly; enhance the anti-jamming capability and noise tolerance. Also it has merits of simple structure and lower cost.
Owner:TAIYUAN UNIV OF TECH
Polarization-OTDR for measuring characteristics of optical fibers
InactiveUS20030174312A1Reflectometers dealing with polarizationMaterial analysis by optical meansStatistical analysisOptical time-domain reflectometer
In a method of polarization optical time-domain reflectometer (P-OTDR) for measuring a parameter of an optical transmission path, for example an optical fiber, by transmitting pulses of light into the path and measuring the state of polarization of backscattered light against distance, statistical analysis of the degree of polarization (DOP) of the backscattered signal is used to detect sections of an optical transmission path for which mode-coupling behaviour (long h) leads to high PMD. Preferably, successive DOP measurement are taken with different state of polarization, SOP, for the P-OTDR light source.
Owner:EXFO ELECTRO OPTICAL ENG
Method for simultaneously measuring distributed type temperatures and strain
ActiveCN103674084AReduce complexityReduce manufacturing costThermometers using physical/chemical changesUsing optical meansTime-domain reflectometerRayleigh scattering
The invention provides a method for simultaneously measuring distributed type temperatures and strain. A brillouin optical time domain reflectometer and a coherent light time domain reflectometer share the same optical path system and the same circuit system and serve as a sensing measurement system. The sensing measurement system works in a BOTDR mode and a COTDR mode in an alternate mode to measure a brillouin scattering spectrum and a Rayleigh scattering spectrum which are distributed along a single single-mode sensing optical fiber and detect the frequency shift of the brillouin scattering spectrum and the frequency shift of the Rayleigh scattering spectrum, a linear equation set in two unknowns about the temperature and the strain is set up according to the characteristic that the frequency shift of the two scattering spectra is in the linear relationship with the temperature and the strain, and the temperature and the strain of each position of the sensing optical fiber can be obtained by solving the equation set, and then the temperatures and the strain distributed along the whole sensing optical fiber can be obtained. According to the method, the complexity and the manufacturing cost of the system are greatly reduced, no special requirement for the brillouin frequency shift coefficient of the optical fiber exists, and the application range of the measurement system is enlarged.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING)
Centralized monitoring and managing system for optical cable resources
ActiveCN102523037ASafe and stable operationComprehensive management functionsTransmission monitoring/testing/fault-measurement systemsFiberSystems management
The invention relates to a centralized monitoring and managing system for optical cable resources. A system structure based on two stages of monitoring and managing platforms and a layer of monitoring and operating platform is at least regulated and controlled by the two stages of monitoring centers of a province and city stage and a region stage, and the monitoring of various modes of optical time domain reflectometer (OTDR) test, light power test, linking test thereof and the like is also provided to an optical fiber in use or a standby fiber in an optical fiber network at an executing lay by a plurality of monitoring stations correspondingly. The system also provides an abundant system managing function; especially, a resource topology drawing of an entire network can be drawn according to the configuration parameter of the system; and the operation of quick and accurate positioning during maintenance and fault examination is assisted by utilizing a geographic information system (GIS) technology. Therefore, according to the system disclosed by the invention, the expense of manpower and financial resources for maintenance and management can be effectively reduced, and the time of fault diagnosis and treatment is effectively shortened, so that the safe and stable running of the entire network is ensured.
Owner:SHANGHAI MUNICIPAL ELECTRIC POWER CO +1
Optical line terminal (OLT) optical module integrating optical time domain reflectometer (OTDR) monitoring function
ActiveCN102170309AElectromagnetic transceiversStar-type electromagnetic networksTime-domain reflectometerOptical line termination
The invention discloses an optical line terminal (OLT) optical module, which comprises an optical device, a passive optical network (PON) data signal driver, a PON data signal amplitude limiting amplifier and an optical time domain reflectometer (OTDR) data processing module, wherein the optical device comprises a wavelength division multiplexer (WDM). The OLT optical module can simplify a network wiring structure, and compared with the prior art, reduces OTDR equipment and the WDM as well as the wiring difficulties and network cost of a PON system.
Owner:SOURCE PHOTONICS CHENGDU
Fault location apparatus and procedures in CWDM business applications using wavelength selective OTDR
ActiveUS7042559B1Material analysis by optical meansReflectometers detecting back-scattered light in time-domainTime domainFiber
A method for verifying fiber connections and diagnosing loss of light or loss of signal conditions in a WDM optical system. The method utilizes an optical time domain reflectometer (OTDR) having user-selectable wavelengths to shoot OTDR traces at a specified wavelength corresponding to an optical data-bearing channel into a selected one of a plurality of optical fiber transmission lines that are connected to a multiplexer that respectively multiplexes a data bearing channel carried on each of the plurality of optical fiber transmission lines onto a trunk, or a demultiplexer that demultiplexes multiplexed data bearing channels from the trunk. The OTDR receives backscattered light from the selected optical fiber transmission line and generates a trace of the backscattered light, thereby enabling a fault location in the WDM optical system to be determined from the trace.
Owner:AMERICAN TELEPHONE & TELEGRAPH CO
Raman amplifier system and method with integrated optical time domain reflectometer
ActiveUS20140077971A1Security mechanismElectric signal transmission systemsLaser detailsFiberTime domain
Raman amplifier systems and methods with an integrated Optical Time Domain Reflectometer (OTDR) for integrated testing functionality include an amplifier system, an OTDR and telemetry subsystem, and a method of operation. The OTDR and telemetry subsystem is configured to operate in an OTDR mode when coupled to a line in port and to operate in a telemetry mode when coupled to a line out port. The OTDR and telemetry subsystem enables on-demand fiber testing while also operating as a telemetry channel that is both a redundant optical service channel (OSC) and provides a mechanism to monitor Raman gain over time. The OTDR and telemetry subsystem minimizes cost and space by sharing major optical and electrical components between the integrated OTDR and other functions on the Raman amplifier.
Owner:CIENA
Optical time domain reflectometer simultaneously sensing temperature and stress
InactiveCN104180833AReduce the impact of noiseReduce the scattered light signal-to-noise ratioConverting sensor output opticallyFiberData acquisition
Disclosed is an optical time domain reflectometer simultaneously sensing temperature and stress. The system is based on parallel detection of Rayleigh and Brillouin scattered light and includes devices such as a multi-wavelength laser source, a light-pulse modulator, a balance detector, a microwave amplifier, a high-speed data acquisition card, a coupler and a circulator and the like. In the optical time domain reflectometer, the frequency interval of wavelengths of the multi-wavelength laser source is arranged to be in a range of 9-12 GHz, which is equivalent to a frequency shift quantity of Brillouin scattered light in a fiber. A heterodyne coherent detection method is used to carry out parallel detection on Rayleigh and Brillouin scattered spectra and temperature and stress information is demodulated through a Landau-Placzek ratio (LPR) and Brillouin frequency shift distribution; and at the same time, coherent Rayleigh noises are reduced and superposition of the scattered spectra improves the signal-to-noise ratio of the scattered light. The optical time domain reflectometer is capable of realizing simultaneous temperature and stress sensing of a distributed fiber sensing system, improving the signal-to-noise ratio of the scattered light and improving the sensing precision and distance.
Owner:SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
Method for automatically monitoring and maintaining optical cable
InactiveCN102098100AImprove battery lifeReduce power consumptionTelephonic communicationElectromagnetic transmissionGeneral Packet Radio ServiceGeographic site
The invention discloses a method for automatically monitoring and maintaining an optical cable. The method comprises the following steps of: automatically monitoring the power of the optical cable by a power meter and giving an alarm; when the power of the optical cable is alarmed, determining the alarm level of the optical power, and driving an optical time domain reflectometer module to test the optical cable; automatically analyzing whether the optical cable is broken and determining the breakpoint distance according to a test result; automatically calculating the geographical position of the breakpoint through optical cable facility information; automatically transmitting a short message to the mobile phone of an optical cable maintainer; and making an emergency maintenance by the maintainer or a manager. The invention is characterized in that: the method replaces the traditional polling mode so as to reduce the electric consumption, greatly improve the cruising capability of a handheld intelligent terminal, and improve the availability of the whole system; the optical cable is not required to be communicated with a server frequently so as to greatly save a general packet radio service (GRPS) flow; and when the optical cable is out of service, the server immediately transmits the message to the handheld intelligent terminal; and compared with the polling mode, the method has higher real time.
Owner:GUANGXUN SCI & TECH WUHAN +1
Optical Transceiver Integrated with Optical Time Domain Reflectometer Monitoring
ActiveUS20120243863A1Improve protectionGuaranteed successTransmission monitoringTransmission monitoring/testing/fault-measurement systemsTime-domain reflectometerTime domain
An optical transceiver having an integrated optical time domain reflectometer monitoring unit and methods for using the same are disclosed. The disclosure relates to an optical transceiver comprising an optical device comprising a wavelength division multiplexing system (WDM), a data signal driver, a data signal limiting amplifier, and an optical time domain reflectometer (OTDR) data processing module. Furthermore, the optical transceiver is particularly advantageous in an optical line terminal (OLT) and / or a passive optical network (PON). The integrated OTDR data processing module can protect the optical transceiver, ensure successful monitoring data, simplify network wiring and decrease system and network costs by decreasing the number of OTDR modules and WDM units.
Owner:SOURCE PHOTONICS
Online traffic volume monitoring system and method based on phase-sensitive optical time domain reflectometry
ActiveUS20160275788A1Low costHigh sensitivityDetection of traffic movementCharacter and pattern recognitionFiberPhase sensitive
An online traffic volume monitoring system based on a phase-sensitive optical time domain reflectometry and its monitoring method are related to a field of intelligent transportation and an application of distributed fiber sensing. A vehicle moving temporal-spatial response graph is generated by accumulating differentiated Optical Time-Domain Reflectometry tracks at different moments in one unit monitoring period for traffic volume statistics, and then converted into a vehicle moving trajectory image through binarization and image pre-processing. Parameters of the moving vehicles are detected by utilizing a search-match method. A traffic volume, moving speeds, moving directions and locations are obtained respectively from detected trajectory number, and a tilt angle and pixel positions. The monitoring method is helpful to solve traffic congestion problem and informing drivers of real-time traffic volume, and contributes to realize an intelligent city traffic regulation.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA
Method and apparatus using polarisation optical time domain reflectometry for security applications
InactiveUS7173690B2Detection of fluid at leakage pointWave based measurement systemsPolarizerRayleigh backscattering
A preferred apparatus and method is presented in which a distributed fiber optic sensor is used in order to detect a disturbance along its length. A pulse of polarized light is launched into an optical fiber; as the pulse propagates along the optical fiber, it continuously loses a small portion of its energy due to Rayleigh backscatter. The Rayleigh backscattered light is analyzed using a polarization sensitive element such as a fiber polarizer. The dynamics of the time dependence of the polarization analyzed backscattered light is used to ascertain if there has been a disturbance along the length of the optical fiber. This technique can be used for applications in areas such as fiber optic telecommunications, perimeter security, fire detection, and pipelines.
Owner:SENSTAR CORP
Method for precisely positioning fault of optical cable by utilizing rayleigh scattering and coherent optical time domain reflection technology
InactiveCN103051377AAchieve precise positioningShorten the timeElectromagnetic transmissionRayleigh scatteringTime domain
The invention discloses a method for precisely positioning a fault of an optical cable by utilizing rayleigh scattering and coherent optical time domain reflection technology. The method comprises the following steps of utilizing the coherent optical time domain reflection and rayleigh scattering technology, wherein rayleigh scattered light carries each distributed point information of the optical cable according to the optical time domain reflection principle, and the distributed point information of the optical cable comprises strength information caused by loss and phase information of an interferometer based on Sagnac ring principle caused by external disturbance; testing the positioning of the optical cable by combining an ultrasonic vibrator with a Rayleigh scattered optical time domain reflectometer, finding out the position of a vibration point, re-utilizing a method of combining absolute positioning with relative positioning, and carrying out successive approximation to finally realize precise positioning of the optical cable. Compared with the prior art, the method for precisely positioning the fault of the optical cable by utilizing the rayleigh scattering and coherent optical time domain reflection technology, disclosed by the invention, has the advantages of simplicity in operation, small calculated amount, shortened time for finding out a fault point and reduced maintenance cost.
Owner:GUILIN G LINK TECH
Wavelength-encoding optical time domain reflection test device and measurement method thereof
ActiveCN101764646AReduce noiseReduce Spontaneous Emission NoiseFibre transmissionOptical apparatus testingTime domainPhotovoltaic detectors
The invention discloses a wavelength-encoding optical time domain reflection test device and a measurement method thereof. The device comprises an optical wavelength encoding generator, an optical fiber splitting device, a polarization controller, an optical fiber coupler, a photoelectric detector and a beat frequency signal detection device; wherein an encoding optical pulse signal generated from the optical wavelength encoding generator is input from a first port of the optical fiber splitting device and divided into a detection light signal and a reference light signal which are respectively output from a second port and a third port of the optical fiber splitting device; the detection light source enters into an optical fiber link to be tested, and a reflected light signal generated after meeting breakpoints or damages of the optical fiber link to be tested returns to the optical fiber splitting device from the second port and is output from a fourth port; the reflected light signal passes through the polarization controller, then passes through the optical fiber coupler together with the reference light signal and enters into the photoelectric detector to carry out frequency beating, and a beat-frequency low-frequency signal enters into the beat-frequency signal detection device and is then observed and recorded. The invention solves the problems that the OTDR resolution ratio and the dynamic range of the traditional device can not be simultaneously improved.
Owner:INST OF SEMICONDUCTORS - CHINESE ACAD OF SCI
Phase-sensitive optical time domain reflectometer type optical fiber distributed disturbing sensor of double-arm pulse optical interference
InactiveCN102538846AHigh detection sensitivityConverting sensor output opticallyRayleigh scatteringTime domain
The invention relates to the technical field of the optical fiber sensor, providing a phase-sensitive optical time domain reflectometer type optical fiber distributed disturbing sensor of double-arm pulse optical interference. By adopting a laser that is narrow in line width, large in power and low in frequency drift, the phase-sensitive optical time domain reflectometer type optical fiber distributed disturbing sensor of double-arm pulse optical interference provided by the invention based on the phase-sensitive optical time domain reflection technology can position the disturbing signals in a single point or multiple points simultaneously through interference of backward Rayleigh scattering light in two sensing arms pulse width areas by comparing the signals after and before disturbance. By extracting the phase information in a trigonometric function for large numbers accumulation or average, the invention improves the sensitivity of the system equivalently. The invention improves the sensitivity of the system by way of square or exponentiation. Finally, optimally, PGC (phase generated carrier) algorithm is used to extract the phase information so as to eliminate the influence of random change of scattered signals, thereby improving the sensitivity of the system equivalently.
Owner:BEIHANG UNIV
Brillouin optical time domain reflectometer for single-photon detection based on edged filter method
InactiveCN102620857ASimple structureReduce volumeThermometers using physical/chemical changesUsing optical meansTime correlationPhoton detection
The invention discloses a Brillouin optical time domain reflectometer for single-photon detection based on an edged filter method, which comprises a narrow linewidth laser (1), a pulse modulator (2), a circulator (3), a sensing optical fiber (4), an optical fiber module (5), 3dB coupler (6), a linear edged filter (7), an InGaAs / InP SPAD (single-photon avalanche diode) detector group (8), a signal generator (9), a data processing module (10) and a pulse signal generator (11), wherein the InGaAs / InP SPAD detector group (8) includes two or three InGaAs / InP SPAD detectors. The InGaAs / InP SPAD detector group with a high counting rate and high sensitivity is used as a detection unit, Brillouin frequency shift information is acquired by the edged filter method, time correlation single-photon counting technology is adopted by the data processing module (10), limitations on the bandwidth and sensitivity of a traditional detector are broken through, spatial resolution and measuring precision of the reflectometer can be simultaneously improved, and temperature and strain are simultaneously sensed.
Owner:NANJING FAAIBO OPTOELECTRONICS TECH
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