759 results about "Optical time-domain reflectometer" patented technology

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.

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.

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.

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.

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.

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.

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.

The invention relates to a BOTDR (Brillouin Optical Time Domain Reflectometer) for calibrating optical power of reference light and a calibrating method thereof. The calibrating method comprises the following steps of: acquiring an electric signal of local reference light from a heterodyne photoreceiver on a basis of a traditional BOTDR for heterodyne coherent detection; transmitting the electric signal subjected to analog-to-digital conversion in a computer to be used as the optical power calibrating feedback quantity of the reference light; sending out an instruction by the computer to adjust the output power of a microwave source and change the optical power of the local reference light so that the difference between the optical power of the local reference light and the preset reference light power is smaller than a set value; calibrating the power; and detecting a BOTD signal. In the invention, the BOTDR in a working process can not be influenced by the working environment temperature, a microwave transmission line connecting the microwave source with an electro-optic modulator and different power responses of the electro-optic modulator on microwave signals of different frequencies, the error between the reference light power at different frequency points and the preset power is smaller than a set value, and the accurate measurement of the stress and the temperature is ensured.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

The invention discloses a spontaneous Brillouin scattering optical time domain reflectometer (BOTDR) based on a superconductive nanowire single-proton detector, which is characterized in that an optical pulse emitted by an optical pulse generating unit is coupled to a sensing optical fiber through a circulator, backward scattered light scattered from the sensing optical fiber is subjected to filtration of rayleigh scattering light through an optical filter unit to obtain Brillouin scattering light, a back scattering light signal is detected by the superconductive nanowire single-proton detector, an electric signal output from the superconductive nanowire single-proton detector is acquired and processed by a data acquiring and processing unit, and finally, a result is obtained through a certain demodulation relation. Compared with the traditional BOTDR, the BOTDR provided by the invention is used for carrying out data acquisition and processing by adopting the noise equivalent power (NEP) low/no-bandwidth-limit superconductive nanowire single-proton detector as a detection unit and adopting a single-proton counting technology.