WO2023160490A1 - 一种传输信号的方法和装置 - Google Patents

一种传输信号的方法和装置 Download PDF

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Publication number
WO2023160490A1
WO2023160490A1 PCT/CN2023/077123 CN2023077123W WO2023160490A1 WO 2023160490 A1 WO2023160490 A1 WO 2023160490A1 CN 2023077123 W CN2023077123 W CN 2023077123W WO 2023160490 A1 WO2023160490 A1 WO 2023160490A1
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Prior art keywords
signal
frequency value
heterodyne frequency
electrical signal
heterodyne
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PCT/CN2023/077123
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English (en)
French (fr)
Inventor
周恩波
李恭鹏
顾堃
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华为技术有限公司
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Publication of WO2023160490A1 publication Critical patent/WO2023160490A1/zh

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/02—Testing optical properties
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/08—Testing mechanical properties
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/08—Testing mechanical properties
    • G01M11/088—Testing mechanical properties of optical fibres; Mechanical features associated with the optical testing of optical fibres
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
    • G01M11/31—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter and a light receiver being disposed at the same side of a fibre or waveguide end-face, e.g. reflectometers
    • G01M11/3109—Reflectometers detecting the back-scattered light in the time-domain, e.g. OTDR
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/071—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using a reflected signal, e.g. using optical time domain reflectometers [OTDR]

Definitions

  • the present application relates to the technical fields of optical fiber testing and optical fiber sensing, and more particularly, to a method and device for transmitting signals.
  • Optical Time Domain Reflectometer is a commonly used optical fiber testing instrument in the field of optical fiber testing technology. It is based on Rayleigh Backscattering (RBS) and Fresnel Reflection (FR) of light. The principle is made.
  • Related extended applications of OTDR such as phase optical time domain reflectometer ( ⁇ -OTDR), Brillouin optical time domain reflectometer (BOTDR) and Raman optical time domain reflectometer (ROTDR) are commonly used in the field of optical fiber sensing Fiber optic testing instruments.
  • ⁇ -OTDR phase optical time domain reflectometer
  • BOTDR Brillouin optical time domain reflectometer
  • ROTDR Raman optical time domain reflectometer
  • OTDR measures the attenuation of the scattered light signal and reflected light signal along the fiber axis during the propagation of the optical signal in the optical fiber, so that it can analyze the uniformity, defect, fracture and joint coupling of the optical fiber. It is an indispensable tool in the process of maintaining and monitoring fiber loss. For example: fiber length detection, power failure detection, joint position detection, attenuation coefficient detection, joint loss, fiber fault point location, and fiber loss, vibration, temperature and stress distribution along the length, etc.
  • OTDR usually has two detection methods for scattered light signals and reflected light signals: direct detection and coherent detection.
  • the OTDR of the direct detection structure directly detects the signal intensity of the scattered light signal and the reflected light signal after the interference of the detector, and the OTDR can accurately obtain the position point of the disturbance signal, and has the function of multi-point positioning.
  • the OTDR with this structure has simple structure, easy pulse generation, short signal processing time, and low cost. It is suitable for scenarios with short sensing distance and low system signal-to-noise ratio (SNR).
  • SNR system signal-to-noise ratio
  • the direct detection OTDR does not use the frequency and phase information of the optical carrier, and its detection sensitivity, dynamic range (Dynamic Range, DR) and dead zone (dead zone, DZ) are poor, and it is difficult to apply to Longer distance fiber optic fault detection.
  • the coherent detection technology is introduced into the OTDR system.
  • the local oscillator light, the scattered light and the reflected light are coherently demodulated, and the signal strength after demodulation is much greater than that in the direct detection OTDR system.
  • the intensity of the scattered light and reflected light signals significantly improves the SNR value of the OTDR system, and the OTDR can detect tiny scattered light and reflected light signals, effectively increasing the dynamic range of the system.
  • commonly used coherent detection OTDR technology can include homodyne coherent reception and heterodyne coherent reception. For OTDR devices, there is a mutual restrictive relationship between its various specifications.
  • the end face reflection and large insertion loss of the optical fiber will cause a large dead zone in the OTDR curve.
  • the use of higher-energy detection pulses can improve the dynamic range but will crack the blind area, degrading the measurement performance of the device, making it difficult to meet the needs of long-distance and high-precision optical fiber detection. Therefore, how to balance the dynamic range, spatial resolution and dead zone of OTDR to realize high-performance OTDR is a technical problem that needs to be solved urgently during the design of the scheme.
  • the embodiment of the present application provides a method and device for transmitting signals. By adaptively adjusting the input signal to meet the detection requirements in different scenarios, the detection of the heterodyne coherent optical time domain reflectometer OTDR device is improved. performance.
  • a method for transmitting signals is provided, which is applied in the field of optical fiber detection systems, and the method includes: generating and sending a first optical signal; receiving a second optical signal, the second optical signal including the first optical signal The reflected and scattered signals of the signal; converting the second optical signal into the first electrical signal; determining the first heterodyne frequency value of the first electrical signal; based on the first heterodyne frequency value of the first electrical signal and the first One or more eigenvalues of the electrical signal determine a second heterodyne frequency value, wherein the eigenvalues of the first electrical signal include: power spectral density, signal-to-noise ratio, dynamic range, and dead zone; according to the second heterodyne frequency value Generate and send a third optical signal.
  • the laser emitting module in the OTDR device generates and sends the first optical signal, reflects or scatters back the second optical signal through the optical fiber under test, and transmits the second optical signal through the photoelectric detection unit in the receiving module.
  • the second optical signal is converted into a first electrical signal, and the first heterodyne frequency value of the first electrical signal is determined, and the signal feedback control module uses the first heterodyne frequency value of the first electrical signal and the first electrical signal
  • the second heterodyne frequency value is determined by one or more eigenvalues; the signal generation module generates a third optical signal according to the second heterodyne frequency value.
  • the heterodyne frequency of the optical signal input by the OTDR device can be adaptively adjusted to meet the detection requirements in different scenarios, and the spatial resolution of the OTDR system can be further improved under the premise of high dynamic range. Rate and dynamic range indicators and improve the distance of the blind zone to improve the detection performance of heterodyne coherent OTDR devices.
  • determining the second heterodyne frequency value according to the first heterodyne frequency value of the first electrical signal and one or more characteristic values of the first electrical signal includes: converting the first electrical signal into a first digital signal; converting the first digital signal into a first time domain signal; converting the first time domain signal into a first frequency domain signal; according to the first frequency domain signal One or more eigenvalues determine the second heterodyne frequency value.
  • determining the second heterodyne frequency value according to the first heterodyne frequency value of the first electrical signal and one or more characteristic values of the first electrical signal includes: converting the first frequency domain signal into a second time domain signal; determining the second heterodyne frequency value according to one or more eigenvalues of the second time domain signal.
  • the method before determining the second heterodyne frequency value according to the first heterodyne frequency value of the first electrical signal and one or more eigenvalues of the first electrical signal, further The method includes: judging the second heterodyne frequency value, wherein, when the absolute value of the difference between the first heterodyne frequency value and the second heterodyne frequency value of the first electrical signal is greater than a judgment threshold, sending the second heterodyne frequency value Two heterodyne frequency values.
  • the heterodyne frequency value when it is detected in the signal feedback control module that the absolute value of the difference between the first heterodyne frequency value and the second heterodyne frequency is greater than the decision threshold, the heterodyne frequency value will be adjusted to the second Heterodyne frequency value, otherwise no adjustment will be made and the original first heterodyne frequency value will be maintained.
  • the heterodyne frequency value can be adjusted by setting a threshold value to improve the OTDR device. Detection accuracy to meet the detection requirements of heterodyne coherent OTDR devices in different scenarios.
  • generating and sending the third optical signal according to the second heterodyne frequency value includes: determining the second digital signal according to the second heterodyne frequency value, wherein the The second digital signal has the signal characteristic of the second heterodyne frequency value; convert the second digital signal into a second electrical signal; amplify the second electrical signal to obtain a third electrical signal; convert the third electrical signal The signal is converted into a third optical signal.
  • the heterodyne frequency value of the first optical signal is not zero.
  • a device for transmitting signals which is applied in the field of optical fiber detection, including: a laser transmitting module, used to generate and send a first optical signal; a receiving module, used to receive a second optical signal, the first The second optical signal includes reflection and scattering signals of the first optical signal; the receiving module is also used to convert the second optical signal into the first electrical signal; signal feedback A control module, configured to determine a second heterodyne frequency value according to the first heterodyne frequency value of the first electrical signal and one or more eigenvalues of the first electrical signal, wherein the eigenvalues of the first electrical signal include: power Spectral density, signal-to-noise ratio, dynamic range, dead zone; a signal generating module, configured to generate and send a third optical signal according to the second heterodyne frequency value.
  • the signal feedback control module includes: an analog-to-digital conversion unit configured to convert the first electrical signal into a first digital signal; a frame calculation unit configured to The first digital signal is converted into a first time-domain signal; the time-frequency transform calculation unit is used to convert the first time-domain signal into a first frequency-domain signal. The calculation unit is used to convert a signal based on the first frequency-domain signal or a plurality of eigenvalues to determine the second heterodyne frequency value.
  • the signal feedback control module further includes: a time-frequency inverse conversion unit, configured to convert the first frequency-domain signal into a second time-domain signal.
  • the signal feedback control module further includes: a judging unit, configured to judge the second heterodyne frequency value, wherein, when the first electrical signal When the absolute value of the difference between a heterodyne frequency value and the second heterodyne frequency value is greater than a decision threshold, the second heterodyne frequency value is sent to the signal generating module.
  • the signal generating module includes: a digital signal generating unit configured to determine a second digital signal according to a second heterodyne frequency value, wherein the second digital signal has The signal characteristics of the second heterodyne frequency value; the first digital-to-analog conversion unit is used to convert the second digital signal into a second electrical signal; the signal amplification unit is used to amplify the second electrical signal to obtain a third electrical signal; an electro-optical modulator, configured to convert the third electrical signal into a third optical signal.
  • a communication device including: various modules or units configured to implement the method in the first aspect or any possible implementation manner of the first aspect.
  • the present application provides a computer-readable storage medium, where computer instructions are stored in the computer-readable storage medium, and when the computer instructions are run on a computer, any one of the first aspect or the first aspect may be implemented. The method in the implementation of is executed.
  • the present application provides a chip, which is characterized in that it includes: a processor, configured to call and run a computer program from a memory, so that the communication device installed with the chip executes any of the first aspect or the first aspect.
  • a processor configured to call and run a computer program from a memory, so that the communication device installed with the chip executes any of the first aspect or the first aspect.
  • the present application provides a computer program product, the computer program product includes computer program code, when the computer program code is run on a computer, the first aspect or any possible implementation of the first aspect The method in the method is executed.
  • Fig. 1 is a schematic structural block diagram of a heterodyne coherent OTDR device provided by an embodiment of the present application.
  • FIG. 2 is a schematic structural diagram of an example of a signal feedback control module provided by an embodiment of the present application.
  • FIG. 3 is a schematic structural diagram of an example of a signal detection and calculation unit provided by an embodiment of the present application.
  • Fig. 4 shows a schematic structural diagram of an example of a signal generating module provided by an embodiment of the present application.
  • FIG. 5 shows a schematic flow diagram of an example of a method for adaptively adjusting heterodyne frequency values based on OTDR provided by the present application.
  • FIG. 6 is a flow chart of an example of a calculation method for a heterodyne frequency value in an OTDR system provided by an embodiment of the present application.
  • Fig. 7 is a flowchart of a method for dynamically adjusting heterodyne frequency values in a ⁇ -OTDR system provided by the present application.
  • Fig. 8 is a schematic block diagram of a communication device provided by an embodiment of the present application.
  • the technical solutions of the embodiments of the present application can be applied to various OTDR-based distributed optical fiber testing technical fields and optical fiber sensing technical fields, such as: ordinary optical time domain reflectometry (Optical Time Domain Reflectometry, OTDR), polarization-sensitive optical time domain Reflectometer (Polarization Optical Time Domain Reflectometry, POTDR), Phase-Sensitive Optical Time Domain Reflectometry (Phase-Sensitive Optical Time Domain Reflectometry, ⁇ -OTDR), Brillouin Optical Time Domain Reflectometry (BOTDR) ) and Raman Optical Time Domain Reflectometry (Raman Optical Time Domain Reflectometry, ROTDR), etc., which are not limited in this embodiment of the present application.
  • ordinary optical time domain reflectometry Optical Time Domain Reflectometry, OTDR
  • POTDR Polarization-sensitive optical time domain Reflectometer
  • Phase-Sensitive Optical Time Domain Reflectometry Phase-Sensitive Optical Time Domain Reflectometry
  • OTDR is an optoelectronic integration that uses the scattering of optical signals in the optical fiber under test, including Rayleigh scattering, Brillouin scattering and Raman scattering, and the Fresnel reflection of optical signals at discontinuous points in the optical fiber.
  • OTDR is a fiber optic testing instrument used for characteristic analysis, troubleshooting and maintenance of fiber optic links. OTDR testing is performed by transmitting pulsed laser light in the fiber and analyzing it. The working principle of OTDR is to analyze the length, attenuation, fault and other transmission characteristics of the optical fiber by detecting the energy distribution curve of the backscattered light of the pulsed laser on the optical fiber line with time or distance. That is, an optical pulse signal is input to the optical fiber under test. When the optical pulse propagates forward along the optical fiber line, it will scatter and reflect back part of the optical ring signal. Continuous high-speed sampling of this optical signal can reflect the attenuation and fault of the optical fiber. characteristic curve.
  • heterodyne coherent detection type ⁇ -OTDR is usually used.
  • its structure mainly includes a laser, a beam splitter, a modulator, a circulator, an optical fiber under test, a coupler, a photodetector, and a processing unit.
  • the sensor's lasers, beam splitters, modulators, circulators, couplers, photodetectors and other corresponding power supplies, drivers, circuit units and communication interfaces can be integrated into the same sensor processing device.
  • the measuring fiber is usually arranged in the sensing fiber optic cable.
  • the specific working principle of the heterodyne coherent detection type ⁇ -OTDR device is as follows: the continuous light generated by the laser as a light source is divided into upper and lower paths through the optical splitter, the lower path light is sent to the coupler as local oscillator light, and the upper path is used as the detection light through
  • the modulator is modulated into an optical pulse and injected into the fiber under test through one port of the circulator, and the Rayleigh backscattered light generated in the fiber under test is injected into the coupler through the other port of the circulator to mix with the local oscillator signal. Frequency, and inject the mixed optical signal into the photodetector to detect the output electrical signal, and finally through the analog-to-digital converter (ADC), data acquisition card or oscilloscope in the processing unit for data processing and result display.
  • ADC analog-to-digital converter
  • the heterodyne coherent detection OTDR device can effectively improve the detection sensitivity and dynamic range compared with the traditional OTDR, and can effectively avoid reflections caused by characteristic points such as active connectors and mechanical joints in the test optical fiber link.
  • the blind zone problem caused by the saturation of the receiving end of the OTDR device.
  • Blind areas can include event blind areas and attenuation blind areas.
  • the event blind zone refers to the shortest distance that the OTDR can detect another continuous event after the Fresnel reflection occurs, that is, the sensing length distance from the starting point of the laser pulse reflection peak to the saturation peak of the front-end receiver.
  • the event blind zone is The distance at which the reflection level falls from the peak to 1.5dB.
  • Attenuation dead zone refers to the minimum distance at which OTDR can accurately measure the loss of continuous non-reflective events after Fresnel reflection occurs, that is, the distance from the starting point of the laser pulse reflection peak to other event points that can be identified, also known as optical pulse attenuation blind spot.
  • the attenuation dead zone is 0.5dB from the time the reflection event occurs until the reflection is reduced to the backscattering level of the fiber.
  • the attenuation dead zone is generally longer than the event dead zone.
  • OTDR technology can increase the dynamic range of the system by increasing the pulse width, thereby increasing the measurement range of the OTDR device, but the dead zone of the laser pulse will also increase with the increase of the laser pulse width, which will cause the measurement blind zone to expand and lead to test results cracking.
  • an embodiment of the present application provides a heterodyne coherent detection type OTDR device.
  • a frequency adaptive adjustment module is provided, and the frequency adaptive adjustment module It includes a signal feedback control module and a signal generation module. It finds and adaptively adjusts the optimal heterodyne frequency value of the probe light through the method of calculation and decision feedback, and outputs the optical signal corresponding to the optimal heterodyne frequency value to achieve high Performance heterodyne coherent detection type OTDR device.
  • heterodyne coherent detection OTDR device of the present application will be further described below in conjunction with the accompanying drawings.
  • the following examples are only used to illustrate the technical solutions of the present application more clearly, but not to limit the protection scope of the present application.
  • Fig. 1 is a schematic structural block diagram of a heterodyne coherent OTDR device provided by an embodiment of the present application. It can be seen from FIG. 1 that the heterodyne coherent adaptive heterodyne frequency OTDR device 100 includes a laser emitting module 110 , an optical splitter 120 , a frequency adaptive adjustment module 130 , a circulator 140 , a receiving module 160 and a processing module 170 .
  • the frequency adaptive adjustment module may include a signal feedback control module and a signal generation module.
  • the heterodyne coherent OTDR device may also include a tested optical fiber 150 .
  • the laser emitting module 110 may include a narrow linewidth laser (Narrow Linewidth Laser, NLL), a distributed Bragg grating (Distributed Feedback, DFB) laser and an integrated tunable laser (Integrated Tunable Laser Assembly, ITLA ) and other laser light sources, which are not limited in this embodiment of the present application.
  • NLL narrow Linewidth Laser
  • DFB distributed Bragg grating
  • ITLA integrated Tunable Laser Assembly
  • the output end of the laser emitting module 110 is connected to the input end of the optical splitter 120 .
  • the laser emitting module 110 is used to output continuous optical signals to the input end of the optical splitter 120 .
  • the continuous optical signal generated by the laser emitting module 110 may be the first optical signal.
  • the optical splitter 120 includes two output ports and one input port.
  • the input port of the optical splitter 120 is connected to the output port of the laser emitting module 110
  • the output port of the optical splitter 120 is respectively connected to the input ports of the receiving module 160 and the frequency adaptive adjustment module 130 .
  • the optical splitter 120 is used to divide the continuous optical signal input by the laser transmitting module 110 into two paths, the first path is output to the frequency adaptive adjustment module 130 as a detection optical signal, and the second path is output to the receiving module 160 as a local oscillator optical signal middle.
  • the detected optical signal of the first path split by the optical splitter 120 may be the second optical signal, and the local oscillator optical signal may be the third optical signal.
  • the frequency adaptive adjustment module 130 may include a signal feedback control module and a signal generation module.
  • the frequency adaptive adjustment module 130 is connected to the optical splitter 120, the circulator 140, the receiving module 160 and the processing module 170 respectively.
  • the frequency adaptive adjustment module 130 is used to modulate the detection optical signal sent by the optical splitter 120 into a pulsed optical signal and send it to the first port of the circulator 140, and is used to generate an adjusted optical signal according to the electrical signal sent by the receiving module 160 And sent to the first port of the circulator 140.
  • the frequency adaptive adjustment module 130 modulates the detection optical signal sent by the optical splitter 120, that is, the second optical signal, and the pulsed optical signal can be the fourth optical signal, and the frequency adaptive adjustment module 130 receives The adjusted optical signal generated by the heterodyne frequency value of the first electrical signal sent by the module 160 and one or more eigenvalues of the first electrical signal may be an eighth optical signal.
  • the heterodyne coherent OTDR module may also include an erbium-doped fiber amplifier, which is used to amplify the modulated pulsed optical signal and input it to the first circulator 140. port.
  • an erbium-doped fiber amplifier which is used to amplify the modulated pulsed optical signal and input it to the first circulator 140. port.
  • the erbium-doped amplifier can be connected with the frequency adaptive adjustment module 130 and the first port of the circulator 140 .
  • the circulator 140 includes a first port, a second port and a third port.
  • a circulator 140 is provided at the port of the optical fiber under test to distinguish the incident signal from the reflected signal, and the pulsed laser signal output by the frequency adaptive adjustment module 130 is injected into the optical fiber under test for detection, and the The Rayleigh backscattered light signal reflected upwards is received by the receiving module 160 through the circulator 140 .
  • the circulator 140 can be connected with the frequency The rate adaptive adjustment module 130, the optical fiber under test 150 and the receiving module 160 are connected. Specifically, the first port of the circulator 140 is connected to the output end of the frequency adaptive adjustment module 130 , the second port of the circulator 140 is connected to the optical fiber 150 under test, and the third port of the circulator 140 is connected to the receiving module 160 .
  • the circulator 140 is used for inputting the optical signal generated by the frequency adaptive adjustment module 130 through the first port of the circulator 140, and outputting the optical signal from the second port of the circulator 140 to the optical fiber 150;
  • the Rayleigh backscattered light signal reflected from the optical fiber under test is received, and output to the receiving module 160 through the third port of the circulator 140 .
  • Rayleigh backscattering means that Rayleigh scattering occurs in the fiber medium, and the Rayleigh scattering power of the fiber is distributed throughout the fiber space, and the scattering direction includes forward and backward scattering along the fiber axis in all directions. , where Rayleigh backscattering is the scattering in the fiber in the backward direction along the fiber axis.
  • the detection optical signal output from the second port of the circulator 140 may be the fifth optical signal
  • the Rayleigh backscattered optical signal output from the third port of the circulator 140 may be the sixth optical signal
  • the receiving module 160 may include a coupler 161 and a photodetector 162 .
  • the receiving module 160 is used to couple the Rayleigh backscattered optical signal output from the third port of the circulator 140 and the local oscillator optical signal output by the optical splitter 120 into a seventh optical signal, and pass the photodetection signal to the seventh optical signal. Converter into the first electrical signal output.
  • the coupler 161 is respectively connected to the third port of the circulator 140 and the photodetector 162 .
  • the coupler 161 is configured to couple the Rayleigh backscattered optical signal output from the third port of the circulator 140 with the local oscillator optical signal input by the optical splitter 120 to generate a heterodyne optical signal.
  • the coupler 161 may couple the sixth optical signal input from the third port of the circulator 140 with the third optical signal input from the optical splitter 120 to generate a seventh optical signal.
  • the receiving module 160 in the heterodyne coherent OTDR device 100 further includes an optical filter.
  • the optical filter can be connected to the coupler 161 and the photodetector 162 respectively.
  • the optical filter is used to filter the optical signal output by the coupler 161 and output it to the photodetector 162 .
  • the optical filter can filter the seventh optical signal generated by the coupler 161 and output the filtered seventh optical signal to the photodetector 162 .
  • the photodetector 162 may be connected to the frequency adaptive adjustment module 130 , the coupler 161 and the frequency adaptive adjustment module 130 respectively.
  • the photodetector 162 is configured to convert the input optical signal into an electrical signal, and send the electrical signal to the frequency adaptive adjustment module 130 .
  • the photodetector 162 can convert the seventh optical signal generated by the coupler 161 into the first electrical signal.
  • the heterodyne coherent OTDR device 100 further includes a low noise amplifier, which can be connected to the receiving module 170 and the frequency adaptive adjustment module 130 respectively.
  • the low noise amplifier is used to amplify the weak electric signal filtered by the low pass filter and output it to the processing module 170 .
  • the low-noise amplifier is used to low-pass filter and amplify the second electrical signal output by the frequency adaptive adjustment module 130, and then output it to the processing module 170, wherein the second electrical signal is a frequency-automatic
  • the adaptive adjustment module 130 feeds back the determined electrical signal.
  • the processing module 170 includes a data acquisition card and an oscilloscope, and the processing module 170 is connected with the frequency adaptive adjustment module 130 .
  • a processing module 170 configured to convert the electrical signal input by the frequency adaptive adjustment module 130 into a digital signal and perform processing reason.
  • the data acquisition card is used to convert the input electrical signal into a digital signal, and analyze and collect the data.
  • Oscilloscope for displaying the electrical signal determined by the photodetector.
  • the processing module 170 may convert the electrical signal output by the frequency adaptive adjustment module 130 into a digital signal and perform data processing. It should be understood that the electrical signal is an electrical signal determined by the frequency adaptive adjustment module 130 .
  • the oscilloscope can display the electrical signal determined by the frequency adaptive adjustment module 130 .
  • the above-mentioned heterodyne coherent OTDR device 100 may further include an optical fiber 150 connected to the second port of the circulator 140 .
  • the optical fiber 150 is used to transmit the detection optical signal output from the second port of the circulator 140 , and is used to transmit the Rayleigh backscattered optical signal generated by reflection on the optical fiber 150 to the third port of the circulator 140 .
  • the fifth optical signal output from the second port of the circulator 140 can be transmitted on the optical fiber 150, and the sixth optical signal reflected or scattered back on the optical fiber can be output to the receiver through the third port of the circulator 140.
  • Module 160 the optical signal output from the second port of the circulator 140 may be the initial detection optical signal modulated by the optical signal emitted by the laser emitting module 110 , or the detection light processed by the frequency adaptive adjustment module 130 Signal.
  • the continuous optical signal generated by the laser emitting module 110 can be sent to the input end of the optical splitter 120 as the first optical signal; the optical splitter 120 divides the first optical signal input by the laser emitting module 110 into two paths, and the second The detection optical signal of one path can be a second optical signal and output to the input end of the frequency adaptive adjustment module 130, and the local oscillator optical signal of the second path can be a third optical signal output to the receiving module 160; the frequency adaptive adjustment The pulsed optical signal obtained after the module 130 modulates the second optical signal sent by the optical splitter 120 can be a fourth optical signal, and the frequency adaptive adjustment module 130 can also be based on the first outer signal of the first electrical signal sent by the receiving module 160.
  • the difference frequency value and one or more eigenvalues of the first electrical signal to determine a second heterodyne frequency value, and the adjusted optical signal generated according to the second heterodyne frequency value may be a seventh optical signal;
  • the fourth The optical signal is input through the first port of the circulator 140, and the fifth optical signal is output from the second port of the circulator 140 to the optical fiber under test 150, and the reflected or scattered signal generated by reflection on the optical fiber under test 150 is the sixth optical signal It can be output from the third port of the circulator 140 to the receiving module 160;
  • the coupler 161 in the receiving module 160 can couple the third optical signal and the sixth optical signal, generate the seventh optical signal after mixing, and pass through the photoelectric
  • the first electrical signal is generated and sent to the frequency adaptive adjustment module 130;
  • the frequency adaptive adjustment module 130 is based on the heterodyne value of the first electrical signal and one or more characteristics of the first heterodyne value The value determines a second heterodyne frequency value, and generates a
  • the second heterodyne frequency value is sent; when the first heterodyne frequency value of the first electrical signal.
  • the first heterodyne frequency value of the first electrical signal is retained, and the first electrical signal is output to the signal processing module 170 .
  • FIG. 2 is a schematic structural diagram of an example of the signal feedback control module provided by the embodiment of the present application.
  • FIG. 2 shows a schematic structural diagram of the signal feedback control module 200 in the frequency adaptive adjustment module 130 in the heterodyne coherent OTDR device provided by the embodiment of the present application.
  • the signal feedback control module 200 includes a signal detection and calculation unit 1200 .
  • the signal detection unit 1200 is respectively connected to the receiving module 160, the signal generating module and the signal processing module.
  • the signal detection and calculation unit 1200 is configured to calculate the first heterodyne frequency value of the first electrical signal sent by the receiving module 160 and one or more eigenvalues of the first electrical signal. Two heterodyne frequency values.
  • the characteristic values of the electrical signal received by the signal detection and calculation unit 1200 include: power spectral density (Power Spectral density, PSD), signal-to-noise ratio (Signal-to-Noise Ratio, SNR), dynamic range (Dynamic Range, DR), dead zone (Dead Zone, DZ) and other characteristics.
  • PSD Power Spectral density
  • SNR signal-to-noise ratio
  • SNR signal-to-Noise Ratio
  • DZ Dead Zone
  • the signal detection and calculation unit 1200 can calculate the second heterodyne frequency value by extracting the first heterodyne frequency value and the SNR value in the first electrical signal sent by the receiving module 160 .
  • the signal feedback control module 200 may further include a decision unit 1300 .
  • the decision unit includes two output terminals and one input terminal.
  • the input end of the decision unit 1300 is connected to the output end of the signal detection and calculation unit 1200 , and the output ends of the decision unit 1300 are respectively connected to the input ends of the signal generation module 300 and the signal processing module 170 .
  • the decision unit 1300 is configured to make a decision on the heterodyne frequency value calculated by the signal detection and calculation unit 1200 .
  • the decision unit 1300 may receive the second heterodyne frequency value sent by the signal detection and calculation unit 1200, and make a decision on it. If the absolute value of the difference between the first heterodyne frequency value and the second heterodyne frequency value of the first electrical signal is greater than the decision threshold, then the second heterodyne frequency value is sent to the signal generating module 300 for processing; if The absolute value of the difference between the first heterodyne frequency value of the first electrical signal and the second heterodyne frequency value is less than or equal to the decision threshold, then the first heterodyne frequency value of the first electrical signal is used as the output heterodyne frequency value, and output the first electrical signal to the processing module 170.
  • the above decision threshold may be set according to actual needs, for example, the decision threshold may be set to 1 MHz, which is not limited in this application.
  • FIG. 3 is a schematic structural diagram of the signal detection and calculation unit 1200 in the signal feedback control unit 1300 provided by the embodiment of the present application.
  • the signal detection and calculation unit 1200 includes an analog-to-digital conversion unit 1201 , a framing calculation unit 1202 , a time-frequency conversion calculation unit 1203 and a calculation unit 1207 .
  • the signal detection and calculation unit 1200 may further include a down-conversion calculation unit 1204 , a filtering unit 1205 and a time-frequency inverse conversion unit 1206 .
  • the analog-to-digital conversion unit 1201 is respectively connected to the output end of the receiving module 160 and the input end of the frame calculation unit 1202 .
  • the analog-to-digital conversion unit 1201 is used to convert the analog electrical signal input by the receiving module 160 into a digital signal.
  • the frame fixing calculation unit 1202 is respectively connected to the output terminal of the analog-to-digital conversion unit 1201 and the input terminal of the time-frequency conversion calculation unit 1203 .
  • the framing calculation unit 1202 is used to divide the input digital signal into different groups of time domain signals with the same length.
  • the framing calculation unit 1202 receives the digital signal Et(i) sent by the analog-to-digital conversion unit 1201, and divides the digital signal Et(i) into K groups of time-domain signals whose lengths are all M, and each The lengths of the group time-domain signals are equal and remain the same as the pulse period.
  • the time-frequency conversion calculation unit 1203 is respectively connected to the output terminal of the framing calculation unit 1202 and the input terminal of the down-conversion calculation unit 1204 .
  • the time-frequency transform calculation unit 1203 is used for converting the time-domain signal processed by the frame-fixing calculation unit 1202 into a frequency-domain signal.
  • the signal detection and calculation unit 1200 further includes a down-conversion calculation unit 1204 .
  • the down-conversion calculation unit 1204 is respectively connected to the output terminal of the time-frequency conversion calculation unit 1203 and the input terminal of the filtering unit 1205 .
  • the down-conversion calculation unit 1204 is used to convert the frequency-domain signal obtained by the time-frequency conversion calculation unit into a down-converted frequency-domain signal.
  • the signal detection and calculation unit 1200 further includes a filtering unit 1205 .
  • the filtering unit 1205 is respectively connected to the output terminal of the down-conversion calculation unit 1204 and the input terminal of the calculation unit 1207 .
  • the filtering unit 1205 is used for filtering the frequency domain signal obtained by the down-conversion calculation unit.
  • the filtering unit 1205 can receive the frequency domain signal Ef_DCC(j,l) obtained by the down-conversion calculation unit 1204, and perform filtering processing on it to filter out out-of-band noise, and the filtered frequency domain signal is H*Ef_DDC, where H is the filter function.
  • the signal detection and calculation unit 1200 further includes a time-frequency inverse conversion unit 1206 .
  • the time-frequency inverse transform unit 1206 may be connected to the output terminal of the filtering unit 1205 and the input terminal of the calculation unit 1207 .
  • the time-frequency inverse transformation unit is used to convert the time-frequency signal obtained by the frame-fixing calculation unit 1202 into a frequency-domain signal; it can also be used to convert the frequency-domain signal filtered by the filtering unit 1205 into a frequency-domain signal.
  • the computing unit 1207 is respectively connected to the output terminal of the filtering unit 1205 and the input terminal of the decision unit 1300 .
  • the calculation unit 1207 is used to calculate the second heterodyne frequency value for one or more feature values in the frequency domain signal filtered by the filtering unit or the frequency domain signal output by the time-frequency inverse transformation unit 1206 .
  • FIG. 4 shows a schematic structural diagram of a signal generation module 400 in a heterodyne coherent OTDR device provided by an embodiment of the present application.
  • the signal generation module 400 includes a digital signal generation unit 4010 , a first digital-to-analog conversion unit 4011 , a signal amplification unit 4012 , a signal coupling unit 4013 and an electro-optic modulator 4014 .
  • the signal generation module 400 may further include a photodetection unit 4015 , a bias voltage monitoring unit 4016 and an optical pulse generation unit 4017 .
  • the digital signal generation unit 4010 is respectively connected to the output end of the signal feedback control unit 1300 and the input end of the first digital-to-analog conversion unit 4011 .
  • the digital signal generation unit 4010 is used to generate a digital signal according to the heterodyne frequency value input by the feedback control unit 1300 .
  • the digital signal generation unit 4010 receives the second heterodyne frequency value provided by the signal feedback control unit 1300, the digital signal generation unit 4010 determines the first digital signal according to the second heterodyne frequency value, and converts the The first digital signal is sent to the first digital-to-analog conversion unit 4011 .
  • the first digital-to-analog conversion unit 4011 is respectively connected to the output terminal of the digital signal generation unit 4010 and the input terminal of the signal amplification unit 4012 .
  • the first digital-to-analog conversion unit 4011 is used to convert the input digital signal into an analog electrical signal.
  • the first digital-to-analog conversion unit 4011 converts the first digital signal generated by the digital signal generation unit 4010 into a second electrical signal.
  • the signal amplification unit 4012 is respectively connected to the output terminal of the first digital-to-analog conversion unit 4011 and the input terminal of the signal coupling unit 4013 .
  • the signal amplifying unit 4012 is used to amplify the input analog electrical signal.
  • the signal amplifying unit 4012 may amplify the second electrical signal generated by the first digital-to-analog converting unit 4011 to generate a third electrical signal.
  • the signal coupling unit 4013 is respectively connected to the input terminal of the electro-optic modulator 4014 , the output terminal of the signal amplification unit 4012 and the output terminal of the bias voltage monitoring unit 4016 .
  • the signal coupling unit 4013 is used for combining the amplified analog electrical signal and the bias voltage and inputting it into the optoelectronic modulator 4014 .
  • the electro-optic modulator 4014 is respectively connected to the first port of the optical splitter 110 , the output end of the signal coupling unit 3013 and the input end of the optical pulse generation unit 4017 .
  • the electro-optic modulator 4014 is used to modulate the input analog electrical signal onto the optical carrier, and output it as an optical signal to the optical pulse generating unit.
  • the electro-optic modulator 4014 can modulate the second optical signal and output it to the optical pulse generation unit, and the electro-optic modulator 4014 can also convert the third electrical signal input by the signal coupling unit 4013 into an eighth optical signal. Signal.
  • the electro-optic modulator 4014 may be replaced by the following modulators, for example, an acousto-optic modulator (Acousto-Optic Modulator, AOM), a semiconductor optical amplifier (Semiconductor Optical Amplifier, SOA), an electro-absorption modulator (Electro- Absorption Modulator, EAM), Mach-Zehnder Modulator (Mach-Zehnder Modulator, MZM), etc., which are not limited in this application.
  • modulators for example, an acousto-optic modulator (Acousto-Optic Modulator, AOM), a semiconductor optical amplifier (Semiconductor Optical Amplifier, SOA), an electro-absorption modulator (Electro- Absorption Modulator, EAM), Mach-Zehnder Modulator (Mach-Zehnder Modulator, MZM), etc., which are not limited in this application.
  • the signal generating module 400 further includes an optical pulse generating unit 4017 .
  • the optical pulse generation unit 4017 is connected to the output terminal of the electro-optic modulator 4014, and is used for processing the optical signal input by the electro-optic modulator 4014 and generating a pulsed optical signal.
  • the optical pulse generating unit 4017 can generate a pulse signal within a test period, or generate multiple repeated pulse signals with a fixed pulse width and duty cycle within a test period.
  • the signal generation module 400 further includes a photodetection unit 4015 .
  • the photodetection unit 4015 is respectively connected to the input terminal of the bias voltage monitoring unit 4016 and the output terminal of the electro-optical modulator 4014, and the photodetection unit 3015 is used for detecting the modulated optical signal.
  • the photodetection unit 4015 can detect the second optical signal or the eighth optical signal output by the electro-optical modulator 4014 .
  • the signal generation module 400 further includes a bias voltage monitoring unit 4016 .
  • the bias voltage monitoring unit 4016 is respectively connected to the input end of the signal coupling unit 4013 and the output end of the photodetection unit 4015 .
  • the bias voltage monitoring unit 4016 is used to feed back the bias voltage according to the detection result of the photodetection unit 4015 and lock the bias voltage.
  • the bias voltage monitoring unit 4016 can determine the bias voltage according to the detection result of the second optical signal or the eighth optical signal output by the electro-optical modulator 4014 by the photodetection unit 4015, and is also used to Set voltage lockout.
  • Fig. 5 shows a schematic flow diagram of an example of a method for transmitting a signal provided by the present application.
  • the first optical signal can be used to indicate the continuous optical signal generated by the laser emitting module, and can also be used to indicate the frequency adaptive adjustment module according to the heterodyne frequency value of the last electrical signal and one or more of the electrical signal. Continuous optical signal generated by eigenvalues.
  • the continuous optical signal generated by the laser emitting module is input through the first port of the circulator, and is output from the third port of the circulator to the optical fiber under test.
  • the second optical signal can be used to indicate the local oscillator optical signal generated by the optical splitter when the laser emitting module emits laser light for the first time.
  • the optical signal output from the third port of the number and circulator is mixed and modulated by the receiving module to generate an electrical signal.
  • the second optical signal can also be used to indicate that in the frequency adaptive adjustment process, the optical signal generated and sent by the signal generation module is reflected or scattered back by the optical fiber link to be tested and mixed with the local oscillator optical signal generated by the optical splitter. generated optical signal.
  • the second optical signal is used to indicate the optical signal generated after the optical signal reflected or scattered back from the first optical signal on the optical fiber under test is coupled with the local oscillator optical signal split by the first optical signal through the optical splitter.
  • the second optical signal is also used to indicate an optical signal preset in the OTDR device.
  • a photodetector in the receiving module converts the second optical signal into the first electrical signal.
  • the signal feedback control module acquires the first electrical signal sent by the receiving module, and determines a heterodyne frequency value of the first electrical signal.
  • the first electrical signal may be used to indicate the electrical signal sent by the receiving module to the frequency adaptive adjustment module.
  • the signal feedback control module determines the second heterodyne frequency value according to the first heterodyne frequency value of the first electrical signal and one or more heterodyne frequency values of the first electrical signal.
  • the signal feedback control module includes a signal detection and calculation unit.
  • the signal detection and calculation unit determines the second heterodyne frequency value according to the first heterodyne frequency value of the first electrical signal and one or more characteristic values of the first electrical signal.
  • the characteristic value of the first electrical signal includes: PSD, SNR, DR, DZ and so on.
  • the signal detection and calculation unit may include an analog-to-digital conversion unit, a framing calculation unit, a time-frequency conversion calculation unit, a down-conversion calculation unit, a filtering unit, and a calculation unit.
  • the digital signal Et(i) is sent, and the digital signal Et(i) is divided into K groups of time-domain signals whose lengths are all M, and the length of each group of time-domain signals is equal and remains the same as the pulse period.
  • the signal detection and calculation unit further includes a down-conversion calculation unit.
  • the signal detection and calculation unit further includes a filtering unit.
  • the filter unit can receive the frequency domain signal Ef_DCC(j,l) obtained by the down-conversion calculation unit, and filter it to filter out the out-of-band noise.
  • the above indicators include: PSD, SNR, DR, DZ, etc. of the frequency domain signal.
  • the signal detection and calculation unit further includes a time-frequency inverse conversion unit.
  • the time-frequency inverse transform unit can be combined with the filter unit
  • the output terminal is connected to the input terminal of the computing unit.
  • the time-frequency inverse transform unit is used to transform the time-frequency signal obtained by the frame-fixing calculation unit into a frequency-domain signal.
  • the feedback control module further includes a decision unit. The judgment is used to judge the second heterodyne frequency value calculated by the signal detection and calculation unit.
  • the decision unit may receive the second heterodyne frequency value sent by the signal detection and calculation unit, and make a decision on it. If the absolute value of the difference between the first heterodyne frequency value and the second heterodyne frequency value of the first electrical signal is greater than the decision threshold, the second heterodyne frequency value is sent to the signal generation module for processing; if the first electrical signal If the absolute value of the difference between the first heterodyne frequency value and the second heterodyne frequency value of the signal is less than or equal to the decision threshold, the first heterodyne frequency value of the first electrical signal is retained, and the first electrical signal is output to The processing module performs processing.
  • the above decision threshold may be set according to actual scenario requirements, for example, the decision threshold may be set to 1 MHz, which is not limited in this application.
  • the third optical signal is used to instruct the signal generation module to generate the third optical signal according to the second heterodyne frequency value sent by the signal feedback control module.
  • the signal generation module may include a digital signal generation unit, a first digital-to-analog conversion unit, a signal amplification unit, a signal coupling unit and a modulation unit.
  • the signal generating module may further include the photodetection unit and the bias voltage monitoring unit.
  • the digital signal generating unit receives the second heterodyne frequency value sent by the signal feedback control module, determines the second digital signal according to the second heterodyne frequency, and sends the second digital signal to the first A digital-to-analog conversion unit, wherein the second digital signal has a signal characteristic of a second heterodyne frequency value;
  • the first digital-to-analog conversion unit receives the first digital signal sent by the digital signal generation unit, and converts the first digital signal into The second electrical signal;
  • the signal amplifying unit receives the second electrical signal generated by the first digital-to-analog conversion unit and amplifies the analog electrical signal to generate a third electrical signal;
  • the signal coupling unit receives the second electrical signal amplified and processed by the signal amplifying unit Three electrical signals, combine the analog electrical signal and bias voltage and input it into the photoelectric modulation unit;
  • the modulation unit receives the third electrical signal input by the signal coupling unit, and converts the third electrical signal into a third optical signal .
  • the photodetection unit can detect the optical signal output by the modulation unit; the bias voltage monitoring unit is used to feed back the bias voltage for the detection structure of the photodetection unit and lock the bias voltage.
  • FIG. 6 is a block diagram of a method for calculating a heterodyne frequency value in an OTDR system according to an embodiment of the present application. As shown in Figure 6, the method includes the following steps:
  • the initial heterodyne frequency value in this embodiment of the present application may be 10 MHz.
  • the heterodyne frequency value is gradually increased at a fixed frequency, and the set number of pulses is sent at each heterodyne frequency value ⁇ f, and the corresponding time domain signal E t is collected and recorded, and then used The Fourier transform converts it into a frequency domain signal E f .
  • the fixed frequency of stepping in the embodiment of the present application can be set to 30MHz, and the number of pulses It can be set to 4096 times.
  • the above threshold may be BW 6dB , where BW 6dB is an analog bandwidth value when the receiving end is 6dB, and this value corresponds to 25% of the peak power.
  • the SNR value corresponding to the initial heterodyne frequency value ⁇ f 0 is SNR 0 .
  • the method of calculating the output heterodyne frequency value by gradually increasing the heterodyne frequency value in the OTDR system can be achieved based on the limitation of the analog bandwidth of the current equipment by adaptively optimizing the heterodyne frequency value.
  • the optimal system performance can effectively improve the anti-fiber link reflection capability, reduce the impact of attenuation dead zone, and balance the dynamic range and attenuation dead zone of the OTDR system.
  • Fig. 7 is a flowchart of dynamically adjusting heterodyne frequency values based on the ⁇ -OTDR system provided by the embodiment of the present application. As shown in Figure 7, the dynamic adjustment method of the heterodyne frequency value includes:
  • the heterodyne frequency value A needs to be adjusted, and the adjusted heterodyne frequency value B is input to S703, and the SNR value corresponding to the adjusted heterodyne frequency value B is calculated again.
  • the heterodyne frequency value of , a is a constant coefficient, which is not limited in this embodiment of the present application.
  • S705 if the SNR value is greater than or equal to the SNR threshold, return to S703 after the ⁇ -OTDR system time delay and detect the SNR values at all distances under the heterodyne frequency value again.
  • the ⁇ -OTDR system is delayed for 100 ms and then returned to S703, and the SNR values at different detection distances at the heterodyne frequency value are calculated again.
  • the ⁇ -OTDR system detects the SNR value at all distances, when the fading point at a certain distance is lower than the phase demodulation threshold, that is, when the signal-to-noise ratio of the signal When it is lower than the threshold value, it is difficult to separate the useful signal from it, and when the signal-to-noise ratio of the signal is raised above the threshold value, the useful signal can be separated.
  • the SNR value at a certain distance is lower than the demodulation threshold for a long time, it will easily lead to the formation of a coherent attenuation blind zone in a specific area, which will reduce the measurement accuracy of the ⁇ -OTDR system and seriously reduce the detection performance of the ⁇ -OTDR system.
  • blind spots caused by the saturation of the receiving end of the OTDR system caused by reflections at characteristic points such as active connectors and mechanical joints in the OTDR distributed optical fiber link are called blind spots.
  • the laser pulse reflection peak caused by the access to the active connector in the optical fiber, the distance from the starting point of the laser pulse reflection peak to other identifiable time points is called the optical pulse attenuation dead zone.
  • the above method of adaptively adjusting the heterodyne frequency value is adopted to adjust the heterodyne frequency value below the phase demodulation threshold, so that the measurement accuracy at this distance is improved. Avoid affecting the detection performance of the ⁇ -OTDR system due to blind spots. But at the same time, the SNR value at the distance adjacent to this place will be affected by the external The change of the difference frequency value causes its SNR value to be lower than the demodulation threshold value. It is necessary to make multiple dynamic adjustments to the heterodyne frequency value at different distances to avoid the long-term attenuation blind zone at a specific distance and limit the detection accuracy of the ⁇ -OTDR system.
  • the self-adaptive adjustment of the heterodyne frequency value can be realized by way of decision feedback, so as to avoid the failure to demodulate the phase at a specific distance for a long time at the coherent fading point, which is effective Avoiding the formation of coherent attenuation dead zone at a specific distance, thereby improving the performance of the all-fiber link of the ⁇ -OTDR system, and further improving the detection performance of the ⁇ -OTDR system.
  • Fig. 8 is a schematic block diagram of a communication device provided by an embodiment of the present application.
  • the communication device may include: a receiving unit 810 , a sending unit 820 and a processing unit 830 .
  • the communication device 800 may include units for performing various methods in the method 500 in FIG. 5 . Moreover, each unit in the communication device 800 and the above-mentioned other operations and/or functions are respectively intended to implement a corresponding flow of the method 500 in FIG. 5 .
  • the sending unit 810 is configured to send the first optical signal.
  • the sending unit 810 is further configured to send a third optical signal.
  • the receiving unit 820 is configured to receive the second optical signal, where the second optical signal includes reflection and scattering signals of the first optical signal.
  • the processing unit 830 is configured to convert the second optical signal into the first electrical signal.
  • the processing unit 830 is further configured to determine a second heterodyne frequency value according to the first heterodyne frequency value of the first electrical signal and one or more eigenvalues of the first electrical signal, wherein the eigenvalue of the first electrical signal Including: power spectral density, signal-to-noise ratio, dynamic range, dead zone.
  • the processing unit 830 is further configured to generate a third optical signal according to the second heterodyne frequency value.
  • the processing unit 830 is further configured to convert the third frequency domain signal into a second time domain signal; and determine a second heterodyne frequency value of the second signal according to one or more characteristics of the second time domain signal.
  • the processing unit 830 is further configured to, before determining the second heterodyne frequency value according to the first heterodyne frequency value of the first electrical signal and one or more characteristic values of the first electrical signal, The frequency value is judged, wherein, when the absolute value of the difference between the first heterodyne frequency value and the second heterodyne frequency value of the first electrical signal is greater than a judgment threshold, the second heterodyne frequency value is sent.
  • the processing unit 830 is further configured to determine a second digital signal according to the second heterodyne frequency value, where the second digital signal has a signal characteristic of the second heterodyne frequency value; convert the second digital signal into a first second electrical signal; amplifying the second electrical signal to obtain a third electrical signal; combining the third electrical signal and a bias voltage and inputting it into the photoelectric modulation unit; converting the third electrical signal into a third optical signal.
  • the processing unit 830 is further configured to detect the third optical signal; determine the bias voltage according to the detection result of the third optical signal, and lock the bias voltage to fix the adjusted second heterodyne frequency value.
  • processing unit 830 in the communication device 800 may be implemented by at least one processor.
  • processing unit 830 in the communication device 800 may be implemented by a processor, a microprocessor, or an integrated circuit integrated on the chip or chip system.
  • the disclosed devices and methods may be implemented in other ways.
  • the device embodiments described above are only illustrative.
  • the division of the units is only a logical function division. In actual implementation, there may be other division methods.
  • multiple units or components can be combined or May be integrated into another system, or some features may be ignored, or not implemented.
  • the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be in electrical, mechanical or other forms.
  • a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer.
  • an application running on a computing device and the computing device can be components.
  • One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between two or more computers.
  • these components can execute from various computer readable media having various data structures stored thereon.
  • a component may, for example, be based on a signal having one or more packets of data (e.g., data from two components interacting with another component between a local system, a distributed system, and/or a network, such as the Internet via a signal interacting with other systems). Communicate through local and/or remote processes.
  • packets of data e.g., data from two components interacting with another component between a local system, a distributed system, and/or a network, such as the Internet via a signal interacting with other systems.
  • the processor in the embodiments of the present application can be a central processing unit (Central Processing Unit, CPU), and can also be other general-purpose processors, digital signal processors (Digital Signal Processor, DSP), application-specific integrated circuits (Application Specific Integrated Circuit, ASIC), Field Programmable Gate Array (Field Programmable Gate Array, FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof.
  • a general-purpose processor can be a microprocessor, or any conventional processor.
  • the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, each unit may exist separately physically, or two or more units may be integrated into one unit.
  • the functions described above are realized in the form of software function units and sold or used as independent products, they can be stored in a computer-readable storage medium.
  • the technical solution of the present application is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the various embodiments of the present application.
  • the medium includes: a USB flash drive, a removable hard disk, a read-only memory (Read-Only Memory, ROM), a random access memory (Random Access Memory, RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
  • "for indicating” may include both for direct indicating and for indirect indicating.
  • indication information for indicating A it may include that the indication information directly indicates A or indirectly indicates A, but it does not mean that A must be carried in the indication information.
  • specific indication manners may also be various existing indication manners, such as but not limited to, the above indication manners and various combinations thereof.
  • various indication manners reference may be made to the prior art, which will not be repeated herein. It can be known from the above that, for example, when multiple pieces of information of the same type need to be indicated, there may be a situation where different information is indicated in different ways.
  • the required indication method can be selected according to the specific needs.
  • the embodiment of the present application does not limit the selected indication method. In this way, the indication method involved in the embodiment of the present application should be understood as covering the There are various methods by which a party can obtain the information to be indicated.
  • serial numbers of the above-mentioned processes do not mean the order of execution, and the order of execution of the processes should be determined by their functions and internal logic, and should not be implemented in this application.
  • the implementation of the examples constitutes no limitation.
  • a corresponds to B means that B is associated with A, and B can be determined according to A.
  • determining B according to A does not mean determining B only according to A, and B may also be determined according to A and/or other information.
  • the above is an example of the three elements of A, B and C to illustrate the optional items of the project.
  • the expression includes at least one of the following: A, B, ..., and X"
  • the applicable entries for this item can also be obtained according to the aforementioned rules.

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Abstract

本申请提供了一种传输信号的方法和装置，包括：生成并发送第一光信号；接收第二光信号，该第二光信号包括第一光信号的反射和散射信号；将第二光信号转换成第一电信号；确定该第一电信号的第一外差频率值；根据该第一电信号的第一外差频率值和该第一电信号的一个或多个特征值确定第二外差频率值；根据该第二外差频率值生成并发送第三光信号。本申请提供的方法可应用于外差相干型光时域反射仪OTDR装置，通过对输入的光信号进行自适应调整，可保证在高动态范围的前提下进一步提升OTDR系统的空间分辨率和动态范围指标，以及改善盲区距离，进而提高外差相干型OTDR装置的检测性能。

Description

一种传输信号的方法和装置
本申请要求于2022年2月24日提交中国国家知识产权局、申请号为202210175621.8、申请名称为“一种传输信号的方法和装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光纤测试技术领域和光纤传感技术领域，并且更具体地，涉及一种传输信号的方法和装置。
背景技术
光时域反射仪(Optical Time Domain Reflectometer,OTDR)是光纤测试技术领域常用的光纤测试仪器，是根据光的瑞利背向散射(Rayleigh Backscattering,RBS)与菲涅尔反射(Fresnel Reflection,FR)原理制作而成。OTDR的相关拓展应用，例如相位型光时域反射仪(φ-OTDR)、布里渊光时域反射仪(BOTDR)和拉曼光时域反射仪(ROTDR)是在光纤传感领域常用的光纤测试仪器。以下描述中有关OTDR均包括所有φ-OTDR、BOTDR和ROTDR的所有相关拓展应用。
OTDR通过测量光信号在光纤中传播过程中产生的散射光信号和反射光信号沿光纤轴向衰减的情况，从而可分析出光纤的均匀性、缺陷、断裂及接头耦合等若干性能，是光缆施工、维护及监测光纤损耗过程中必不可少的工具。例如：光纤长度检测、断电检测、接头位置检测、衰减系数检测、接头损耗、光纤故障点定位以及光纤沿长度的损耗、振动、温度和应力分布情况等。
目前，OTDR对于散射光信号和反射光信号的探测方式通常有直接探测与相干探测两种。直接探测结构的OTDR由探测器直接探测散射光信号和反射光信号相互干涉后的信号强度，OTDR可以准确地获取扰动信号的位置点，具备多点定位功能。该结构的OTDR结构简单，脉冲产生容易，处理信号过程时间短，成本低廉，适用于传感距离较短，且系统信噪比(Signal-to-Noise Ratio,SNR)较低的场景。然而，受其原理的限制，直接探测型OTDR没有利用光载波的频率和相位信息，其探测灵敏度及动态范围(Dynamic Range,DR)和盲区(dead zone，DZ)等指标较差，难以适用于较长距离的光纤故障检测中。
为了进一步提高传统OTDR装置的探测灵敏度，将相干探测技术引入到OTDR系统中，本振光与散射光和反射光进行相干解调，解调后的信号强度远大于直接探测型的OTDR系统中的散射光和反射光信号强度，使得OTDR系统的SNR值得到显著提升，OTDR可以探测到微小的散射光和反射光信号，有效增加系统的动态范围。目前，常用的相干探测OTDR技术可包括零差相干接收与外差相干接收两种技术方案。对于OTDR装置，其各规格指标之间存在着相互制约关系。例如在非理想光纤链路中，光纤的端面反射和大插损会导致OTDR曲线出现大盲区。采用较大能量的探测脉冲可以提升动态范围但是会裂化盲区，使得装置的测量性能下降，难以满足长距离高精准的光纤检测的需求。因而，如何平衡OTDR的动态范围、空间分辨率和盲区，以实现高性能OTDR是方案设计时亟需解决的技术问题。
发明内容
本申请实施例提供了一种用于传输信号的方法和装置，通过对输入的信号进行自适应调整以适应不同场景下的检测需求，从而提高外差相干型光时域反射仪OTDR装置的检测性能。
第一方面，提供了一种用于传输信号的方法，应用于光纤检测系领域，该方法包括：生成并发送第一光信号；接收第二光信号，该第二光信号包括该第一光信号的反射和散射信号；将第二光信号转换成第一电信号；确定该第一电信号的第一外差频率值；根据该第一电信号的第一外差频率值和该第一电信号的一个或多个特征值确定第二外差频率值，其中，该第一电信号的特征值包括：功率谱密度、信噪比、动态范围、盲区；根据该第二外差频率值生成并发送第三光信号。
从而，根据本申请提供的技术方案，OTDR装置内的激光发射模块通过生成并发送第一光信号，经过被测光纤反射或散射回第二光信号，并经过接收模块中的光电探测单元将第二光信号转换成第一电信号，并确定出该第一电信号的第一外差频率值，信号反馈控制模块通过根据该第一电信号的第一外差频率值和该第一电信号的一个或多个特征值来确定该第二外差频率值；信号生成模块根据该第二外差频率值生成第三光信号。通过本申请提供的技术方案，可针对OTDR装置输入的光信号的外差频率进行自适应调整，以满足不同场景下的检测需求，可保证在高动态范围的前提下进一步提升OTDR系统的空间分辨率和动态范围指标以及改善盲区距离，以提高外差相干型OTDR装置的检测性能。
结合第一方面，在第一方面的某些实现方式中，根据第一电信号的第一外差频率值和第一电信号的一个或多个特征值确定第二外差频率值，包括：将该第一电信号转换为第一数字信号；将该第一数字信号转换为第一时域信号；将该第一时域信号转换成第一频域信号；根据该第一频域信号的一个或多个特征值确定该第二外差频率值。
结合第一方面，在第一方面的某些实现方式中，根据第一电信号的第一外差频率值和第一电信号的一个或多个特征值确定第二外差频率值，包括：将该第一频域信号转换为第二时域信号；根据该第二时域信号的一个或多个特征值确定该第二外差频率值。
结合第一方面，在第一方面的某些实现方式中，根据第一电信号的第一外差频率值和第一电信号的一个或多个特征值确定第二外差频率值之前，还包括：对该第二外差频率值进行判决，其中，当该第一电信号的第一外差频率值与该第二外差频率值的差值的绝对值大于判决阈值时，发送该第二外差频率值。
从而，在本申请中，当在信号反馈控制模块中检测到该第一外差频率值与该第二外差频率的差值的绝对值大于判决阈值时，将调整外差频率值为第二外差频率值，否则不进行调整，保持原第一外差频率值。通过对该第一电信号的第一外差频率值和该第二外差频率值的绝对值的大小与判决阈值进行判决，可以通过设置阈值的方式调整外差频率值，以提升OTDR装置的检测精度，以满足不同场景下外差相干型OTDR装置的检测需求。
结合第一方面，在第一方面的某些实现方式中，根据该第二外差频率值生成并发送第三光信号，包括：根据第二外差频率值确定第二数字信号，其中，该第二数字信号具有该第二外差频率值的信号特征；将该第二数字信号转换成第二电信号；将该第二电信号进行放大处理，得到第三电信号；将该第三电信号转换为第三光信号。
结合第一方面，在第一方面的某些实现方式中，该第一光信号的外差频率值不为零。
第二方面，提供了一种用于传输信号的装置，应用于光纤检测领域，包括：激光发射模块，用于生成并发送第一光信号；接收模块，用于接收第二光信号，该第二光信号包括第一光信号的反射和散射信号；该接收模块，还用于将第二光信号转换成第一电信号；信号反馈 控制模块，用于根据第一电信号的第一外差频率值和第一电信号的一个或多个特征值确定第二外差频率值，其中，该第一电信号的特征值包括：功率谱密度、信噪比、动态范围、盲区；信号生成模块，用于根据该第二外差频率值生成并发送第三光信号。
结合第二方面，在第二方面的某些实现方式中，该信号反馈控制模块包括：模数转换单元，用于将该第一电信号转换为第一数字信号；定帧计算单元，用于将该第一数字信号转换为第一时域信号；时频变换计算单元，用于将该第一时域信号转换成第一频域信号计算单元，用于根据该第一频域信号的一个或多个特征值确定该第二外差频率值。
结合第二方面，在第二方面的某些实现方式中，该信号反馈控制模块还包括：时频逆变换单元，用于将该第一频域信号转换为第二时域信号。
结合第二方面，在第二方面的某些实现方式中，该信号反馈控制模块还包括：判决单元，用于对该第二外差频率值进行判决，其中，当该第一电信号的第一外差频率值与该第二外差频率值的差值的绝对值大于判决阈值时，向信号生成模块发送该第二外差频率值。
结合第二方面，在第二方面的某些实现方式中，该信号生成模块包括：数字信号产生单元，用于根据第二外差频率值确定第二数字信号，其中，该第二数字信号具有该第二外差频率值的信号特征；第一数模转换单元，用于将该第二数字信号转换成第二电信号；信号放大单元，用于将该第二电信号进行放大处理，得到第三电信号；电光调制器，用于将该第三电信号转换为第三光信号。
第三方面，提供了一种通信装置，包括：用于实现第一方面或第一方面任一种可能实现方式中的方法的各个模块或单元。
第四方面，本申请提供一种计算机可读存储介质，所述计算机可读存储介质中存储有计算机指令，当计算机指令在计算机上运行时，使得如第一方面或第一方面任一种可能的实现方式中的方法被执行。
第五方面，本申请提供一种芯片，其特征在于，包括：处理器，用于从存储器中调用并运行计算机程序，使得安装有所述芯片的通信装置执行如第一方面或第一方面任一种可能的实现方式中的方法。
第六方面，本申请提供一种计算机程序产品，所述计算机程序产品包括计算机程序代码，当所述计算机程序代码在计算机上运行时，使得如第一方面或第一方面任一种可能的实现方式中的方法被执行。
附图说明
图1是本申请实施例提供的外差相干型OTDR装置的结构方框示意图。
图2是本申请实施例提供的信号反馈控制模块的一例结构示意图。
图3是本申请实施例提供的信号检测与计算单元的一例结构示意图。
图4示出了本申请实施例提供的信号生成模块的一例结构示意图。
图5示出了本申请提供的基于OTDR的自适应调节外差频率值的方法的一例示意性流程框图。
图6本申请实施例提供的一例在OTDR系统中对外差频率值的计算方法的流程框图。
图7是本申请提供的一例φ-OTDR系统中动态调整外差频率值的方法的流程框图。
图8是本申请实施例提供的通讯装置的示意性框图。
具体实施方式
本申请实施例的技术方案可以应用于各种基于OTDR的分布式光纤测试技术领域和光纤传感技术领域，例如：普通光时域反射仪(Optical Time Domain Reflectometry,OTDR)、偏振敏感光时域反射仪(Polarization Optical Time Domain Reflectometry,POTDR)、相位敏感光时域反射仪(Phase-Sensitive Optical Time Domain Reflectometry,φ-OTDR)、布里渊散射光时域反射仪(Brillouin Optical Time Domain Reflectometry,BOTDR)和拉曼光时域反射仪(Raman Optical Time Domain Reflectometry,ROTDR)等，本申请实施例对此并不限定。
OTDR是利用光信号在被测光纤中产生的散射，包括瑞利散射、布里渊散射和拉曼散射，以及光信号在光纤中不连续点产生的菲涅尔反射，制成的光电一体化仪表。OTDR是一种用于对光纤链路进行特征分析、故障排查和维护的光纤检测仪器，通过在光纤中传输脉冲激光并对其进行分析来执行OTDR测试。OTDR的工作原理是通过检测脉冲激光在光纤线路上的背向散射光随时间或距离的能量分布曲线来分析得到光纤的长度、衰减、故障等传输特性。即向被测光纤输入一个光脉冲信号，当光脉冲沿着光纤线路向前传播的同时，会散射和反射回部分光环信号，连续高速采样出此光信号可得出反映光纤的衰减、故障等特性的曲线。
例如，在光纤振动传感领域通常采用外差相干探测型φ-OTDR。在现有的外差相干型φ-OTDR装置中，其结构主要包括激光器、分光器、调制器、环形器、被测光纤、耦合器、光电探测器以及处理单元等。在实际使用过程中，可将该传感器的激光器、分光器、调制器、环形器、耦合器、光电探测器及其它相应的电源、驱动、电路单元及通信接口集成同一传感处理装置中，被测光纤通常布置在传感光缆中。该外差相干探测型φ-OTDR装置的具体工作原理为：激光器作为光源产生连续光通过分光器被分为上下两路，下路光作为本振光发送至耦合器中，上路作为探测光经调制器调制为光脉冲并通过环形器的一端口注入被测光纤中，在被测光纤产生的瑞利背向散射光经环形器的另一端口注入到耦合器中与本振光信号进行混频，并将混频后的光信号注入到光电探测器中进行探测输出电信号，最后经处理单元内的模数转换器(ADC)、数据采集卡或者示波器进行数据处理及结果显示。
例如，在光纤测试领域外差相干探测型OTDR装置相较于传统OTDR可有效提升探测的灵敏度及动态范围，并能有效避免因测试光纤链路中的活动连接器、机械接头等特征点产生反射引起的OTDR装置接收端饱和而带来的盲区问题。盲区可包括事件盲区与衰减盲区，在利用OTDR技术进行光纤链路的检测时，由于散射光信号和反射光信号的影响，使得在一定的距离或时间内难以检测或准确定位到光纤链路中的事件点和故障点，上述中难以被检测或准确定位的距离即是盲区。具体地，事件盲区是指菲涅尔反射发生后OTDR可检测到另一个连续事件的最短距离，即从激光脉冲反射峰的起始点到前端接收器饱和峰之间的传感长度距离，事件盲区是反射级别从峰值下降到1.5dB处的距离。衰减盲区是指菲涅尔反射发生后OTDR能精准测量连续非反射事件损耗的最小距离，即从激光脉冲反射峰的起始点到可以识别的其他事件点之间的距离，也称为光脉冲衰减盲区。衰减盲区是从反射事件发生时开始直到反射降低至光纤的背向散射级别的0.5dB。此外，衰减盲区一般较事件盲区长。
目前，OTDR技术可通过增加脉冲宽度的方式增加系统的动态范围，从而增加OTDR装置的测量范围，但激光脉冲的盲区也会随激光脉冲宽度的增加而不断增加，使得测量盲区扩大而导致测试结果裂化。
为了进一步提升OTDR装置的检测性能，本申请实施例提供了一种外差相干探测型OTDR装置。在该外差相干探测型OTDR装置中设置有频率自适应调节模块，该频率自适应调节模块 包括信号反馈控制模块和信号生成模块，通过计算并判决反馈的方法寻找和自适应调整探测光的最优外差频率值，并输出该最优外差频率值所对应的光信号，以实现高性能的外差相干探测型OTDR装置。
下面结合附图对本申请的外差相干探测型OTDR装置作进一步描述。以下实施例仅用于更清楚地说明本申请的技术方案，而不能以此来限制本申请的保护范围。
图1是本申请实施例提供的外差相干型OTDR装置的结构方框示意图。由图1可知该外差相干型自适应外差频率OTDR装置100包括激光发射模块110、分光器120、频率自适应调节模块130、环形器140、接收模块160以及处理模块170。其中，频率自适应调节模块可包括信号反馈控制模块和信号生成模块。
可选地，该外差相干型OTDR装置还可包括被测光纤150。
应理解，在本申请实施例中激光发射模块110可包括窄线宽激光器(Narrow Linewidth Laser，NLL)，分布布拉格光栅(Distributed Feedback,DFB)激光器与集成的可调谐激光器(Integrated Tunable Laser Assembly,ITLA)等多种激光光源，本申请实施例对此不做限定。
激光发射模块110的输出端与分光器120的输入端连接。激光发射模块110用于输出连续的光信号至分光器120的输入端。
在一种实现方式中，经激光发射模块110产生的连续光信号可为第一光信号。
可选地，分光器120包括二个输出端口和一个输入端口。其中，分光器120的输入端口与与激光发射模块110的输出端口连接，分光器120的输出端口分别与接收模块160和频率自适应调节模块130的输入端口连接。
分光器120，用于将激光发射模块110输入的连续光信号分成两路，第一路作为探测光信号输出至频率自适应调节模块130中，第二路作为本振光信号输出至接收模块160中。
在一种实现方式中，经分光器120分开的第一路作为探测的光信号可为第二光信号，作为本振光信号可为第三光信号。
频率自适应调节模块130可包括信号反馈控制模块和信号生成模块。
可选地，频率自适应调节模块130分别与分光器120、环形器140、接收模块160和处理模块170连接。
频率自适应调节模块130用于对分光器120发送的探测光信号进行调制成脉冲光信号并发送至环形器140的第一端口，以及用于根据接收模块160发送的电信号生成调整后光信号并发送至环形器140的第一端口。
在一种实现方式中，频率自适应调节模块130对分光器120发送的探测光信号即第二光信号进行调制后的脉冲光信号可为第四光信号，以及频率自适应调节模块130根据接收模块160发送的第一电信号的外差频率值和该第一电信号的一个或多个特征值生成的调整后的光信号可为第八光信号。
可选地，本申请实施例中提供的外差相干型OTDR模块还可包括掺饵光纤放大器，掺饵光纤放大器用于将已经过调制后的脉冲光信号放大并输入至环形器140的第一端口。
掺饵放大器可与频率自适应调节模块130和环形器140的第一端口连接。
环形器140包括第一端口、第二端口及第三端口。
可选地，在测光纤的端口处设置环形器140，可区分入射信号和反射信号，经频率自适应调节模块130输出的脉冲激光信号注入到待测光纤上进行检测，并在该被测光纤上反射回的瑞利背向散射光信号经环形器140被接收模块160接收。可选地，环形器140可分别与频 率自适应调节模块130、被测光纤150和接收模块160连接。具体地，环形器140的第一端口与频率自适应调节模块130的输出端连接，环形器140的第二端口与被测光纤150连接，环形器140的第三端口与接收模块160连接。
环形器140，用于将频率自适应调节模块130生成的光信号由环形器140第一端口输入，从环形器140第二端口输出至光纤150上；还用于从环形器140第二端口处接收从被测光纤反射回的瑞利背向散射光信号，并经环形器140第三端口输出至接收模块160中。
应理解，瑞利背向散射是指在光纤介质中会发生瑞利散射，光纤的瑞利散射功率在整个光纤空间中都有分布，散射方向四面八方包含沿光纤轴向向前及向后的散射，其中，瑞利背向散射为光纤中沿光纤轴向向后方向的散射。
在一种实现方式中，从环形器140第二端口输出的探测光信号可为第五光信号，在环形器140第三端口输出的瑞利背向散射光信号可为第六光信号。
接收模块160可包括耦合器161和光电探测器162。
在一种实现方式中，接收模块160用于将从环形器140第三端口输出的瑞利背向散射光信号和分光器120输出的本振光信号耦合成第七光信号，并经过光电探测器转换成第一电信号输出。
可选地，耦合器161分别与环形器140的第三端口和光电探测器162连接。
耦合器161，用于将环形器140第三端口输出的瑞利背向散射光信号和分光器120输入的本振光信号进行耦合生成外差光信号。
在一种实现方式中，耦合器161可将环形器140第三端口输入的第六光信号与分光器120输入的第三光信号进行耦合后产生第七光信号。
可选地，外差相干型OTDR装置100内的接收模块160还包括光学滤波器。
可选地，该光学滤波器可分别与耦合器161和光电探测器162连接。
光学滤波器用于将耦合器161输出的光信号进行滤波后输出至光电探测器162中。
例如，光学滤波器可对耦合器161产生的第七光信号进行滤波，并将滤波后的第七光信号输出至光电探测器162。
可选地，光电探测器162可分别与频率自适应调节模块130、耦合器161和频率自适应调节模块130连接。
光电探测器162，用于将输入的光信号转换成电信号，并将该电信号发送至频率自适应调节模块130中。
在一种实现方式中，光电探测器162可将耦合器161产生的第七光信号转换成第一电信号。
可选地，外差相干型OTDR装置100还包括低噪声放大器，低噪声放大器可分别与接收模块170和频率自适应调节模块130连接。
低噪声放大器用于将低通滤波器滤波后的微弱电信号进行放大后输出至处理模块170中。
在一种实现方式中，低噪声放大器用于将频率自适应调节模块130输出的第二电信号低通滤波并进行放大后输出至处理模块170中，其中，该第二电信号为经过频率自适应调节模块130反馈确定的电信号。
处理模块170包括数据采集卡与示波器，该处理模块170与频率自适应调节模块130连接。
处理模块170，用于将频率自适应调节模块130输入的电信号转换成数字信号并进行处 理。
其中，数据采集卡，用于将输入的电信号转换成数字信号，并进行数据的分析与采集。
示波器，用于对光电探测器确定的电信号进行显示。
在一种实现方式中，处理模块170可将频率自适应调节模块130输出的电信号转换成数字信号并进行数据处理。应理解，该电信号为经过频率自适应调节模块130确定的电信号。
在一种实现方式中，示波器可对频率自适应调节模块130确定的电信号进行显示。
可选地，上述外差相干型OTDR装置100还可包括光纤150，该光纤150与环形器140的第二端口连接。
光纤150，用于传输环形器140第二端口输出的探测光信号，以及用于向环形器140的第三端口传输在光纤150上反射产生的瑞利背向散射光信号。
在一种实现方式中，环形器140第二端口输出的第五光信号可在光纤150上进行传输，在光纤上反射或散射回的第六光信号可通过环形器140第三端口输出至接收模块160。应理解，该环形器140第二端口输出的光信号可为经激光发射模块110发射出的光信号经调制后的初次探测光信号，也可以是经频率自适应调节模块130处理后的探测光信号。
接下来以信号在不同模块与设备间的走向为例，对该外差相干型OTDR装置的工作原理进行详细解释。
在一种实现方式中，激光发射模块110产生的连续光信号可作为第一光信号发送至分光器120的输入端；分光器120将激光发射模块110输入的第一光信号分成两路，第一路的探测光信号可为第二光信号并输出至频率自适应调节模块130的输入端，第二路的本振光信号可为第三光信号输出至接收模块160中；频率自适应调节模块130对分光器120发送的第二光信号进行调制后得到的脉冲光信号可为第四光信号，以及频率自适应调节模块130还可以根据接收模块160发送的第一电信号的第一外差频率值和该第一电信号的一个或多个特征值来确定第二外差频率值，并根据该第二外差频率值生成的调整后的光信号可为第七光信号；第四光信号经环形器140的第一端口输入，从环形器140的第二端口输出第五光信号至被测光纤150上，在被测光纤150上反射产生的反射或散射信号即第六光信号可从环形器140的第三端口输出至接收模块160中；接收模块160中的耦合器161可对第三光信号与第六光信号进行耦合，混频后产生第七光信号，并经过光电探测器162调制后产生第一电信号并发送至频率自适应调节模块130中；频率自适应调节模块130根据该第一电信号的外差值和该第一外差值的一个或多个特征值确定第二外差频率值，并根据第二外差频率值来生成第七光信号。其中，若当第一外差频率值与第二外差频率值的差值的绝对值大于判决阈值时，发送该该第二外差频率值；当该第一电信号的第一外差频率值与该第二外差频率值的差值的绝对值小于等于判决阈值时，保留该第一电信号的第一外差频率值，并将该第一电信号输出至信号处理模块170中。
为了对自适应调节模块130内的信号反馈控制模块200的工作原理进行详细解释，图2是本申请实施例提供的信号反馈控制模块的一例结构示意图。图2示出了本申请实施例提供的外差相干型OTDR装置内频率自适应调节模块130内的信号反馈控制模块200的结构示意图。该信号反馈控制模块200包括信号检测与计算单元1200。
可选地，信号检测单元1200分别与接收模块160、信号生成模块和信号处理模块连接。
在一种实现方式中，信号检测与计算单元1200用于通过根据接收模块160发送的第一电信号的第一外差频率值和该第一电信号的一个或多个特征值，来计算第二外差频率值。
示例性地，信号检测与计算单元1200接收的电信号的特征值包括：功率谱密度(Power  Spectral density,PSD)、信噪比(Signal-to-Noise Ratio,SNR)、动态范围(Dynamic Range,DR)、盲区(Dead Zone,DZ)等特征。
在一种实现方式中，信号检测与计算单元1200可通过提取接收模块160发送的第一电信号中的第一外差频率值及SNR值，来计算出第二外差频率值。
可选地，该信号反馈控制模块200还可以包括判决单元1300。该判决单元包括两个输出端和一个输入端。
在一种实现方式中，判决单元1300的输入端与信号检测与计算单元1200的输出端连接，该判决单元1300的输出端分别与信号生成模块300和信号处理模块170的输入端连接。
判决单元1300用于对信号检测与计算单元1200计算出的外差频率值进行判决。
在一种实现方式中，判决单元1300可接收信号检测与计算单元1200发送的第二外差频率值，并对其进行判决。若该第一电信号的第一外差频率值与该第二外差频率值的差值的绝对值大于判决阈值，则将该第二外差频率值发送至信号生成模块300进行处理；若该第一电信号第一外差频率值与该第二外差频率值的差值的绝对值小于等于判决阈值，则将该第一电信号的第一外差频率值作为输出的外差频率值，并将该第一电信号输出至处理模块170中。
应理解，上述判决阈值可以根据实际需求进行设定，例如，判决阈值可以设置为1MHz，本申请对此不做限定。
下面将结合图3对该信号反馈控制模块200中的信号检测与计算单元1200的结构原理进行详细说明。图3是本申请实施例提供的信号反馈控制单元1300内的信号检测与计算单元1200的结构示意图。如图3所示，该信号检测与计算单元1200包括模数转换单元1201、定帧计算单元1202、时频变换计算单元1203和计算单元1207。其中，该信号检测与计算单元1200还可包括下变频计算单元1204、滤波单元1205和时频逆变换单元1206。
模数转换单元1201分别与接收模块160的输出端和定帧计算单元1202的输入端连接。该模数转换单元1201用于将接收模块160输入的模拟电信号转换成数字信号。
在一种实现方式中，模数转换单元1201获取接收模块160发送的第一电信号，并将其转换成长度为N的数字信号Et(i)，其中，i＝1,2,…N。
定帧计算单元1202分别与模数转换单元1201的输出端和时频变换计算单元1203的输入端连接。该定帧计算单元1202用于将输入的数字信号分割成不同组长度相同的时域信号。
在一种实现方式中，定帧计算单元1202接收模数转换单元1201发送的数字信号Et(i)，并将该数字信号Et(i)分割成K组长度均为M的时域信号，每组时域信号的长度相等，且保持和脉冲周期相同。第j组的数字时域信号为Et(j,l)，其中，j＝1,2,…,K，l＝1,2,…,M，且N＝K*M。
时频变换计算单元1203分别与定帧计算单元1202的输出端和下变频计算单元1204的输入端连接。该时频变换计算单元1203用于将通过定帧计算单元1202处理得到的时域信号转化为频域信号。
在一种实现方式中，时频变换计算单元1203接收定帧计算单元1202发送的第j组时域信号，并将其转化为频域信号Ef(j,l)，其中，l＝1,2,…,M。应理解，时频变换的方式可以是傅里叶变换计算，即Ef＝F(Et)。依次令j＝1,2,…,K，即执行该步骤K次，可获得K组长度均为M的频域信号Ef(j,l)，其中j＝1,2,…,K，l＝1,2,…,M，且N＝K*M。
可选的，该信号检测与计算单元1200还包括下变频计算单元1204。该下变频计算单元1204分别与时频变换计算单元1203的输出端和滤波单元1205的入口端连接。该下变频计算单元1204用于将时频变换计算单元得到的频域信号转化为下变频后的频域信号。
在一种实现方式中，下变频计算单元1204可将通过时频变换单元1203得到的频域信号Ef(j,l)转化为下变频后的频域信号Ef_DDC(j,l)，其中l＝1,2,…,M。可依次令j＝1,2,…,K，即执行该步骤K次，可获得K组长度均为M的频域信号Ef_DDC(j,l)，其中j＝1,2,…,K，l＝1,2,…,M，且N＝K*M。
可选的，该信号检测与计算单元1200还包括滤波单元1205。该滤波单元1205分别与下变频计算单元1204的输出端和计算单元1207的输入端连接。该滤波单元1205用于将下变频计算单元得到的频域信号进行滤波。
在一种实现方式中，滤波单元1205可接收下变频计算单元1204得到的频域信号Ef_DCC(j,l)，并对其进行滤波处理，以滤除带外噪声，滤波后的频域信号为H*Ef_DDC，其中H为滤波函数。
可选地，该信号检测与计算单元1200还包括时频逆变换单元1206。时频逆变换单元1206可与滤波单元1205的输出端和计算单元1207的输入端连接。该时频逆变换单元用于将通过定帧计算单元1202得到的时频信号转化为频域信号；还可用于将滤波单元1205滤波后的频域信号转化为频域信号。
在一种实现方式下，时频逆变换单元1206可接收滤波单元1205滤波后的第j组频域信号H*Ef_DDC，并将其转化为时域信号E’t(j,l)，其中l＝1,2,…,M。其中，时频逆变换的方式可以是通过反傅里叶变换进行计算，即Ef＝F-1(Et)。
计算单元1207分别与滤波单元1205的输出端和判决单元1300的输入端连接。该计算单元1207用于对通过滤波单元滤波后的频域信号或时频逆变换单元1206输出的频域信号中的一个或多个特征值来计算第二外差频率值。
在一种实现方式中，计算单元1207接收滤波单元1205滤波后的频域信号H*Ef_DDC，并根据该频域信号的至少一个指标确定第二外差频率值△f’＝function(△f,PSD,SNR,…)，其中，上述指标包括：频域信号的PSD,SNR,DR,DZ等。
可选地，计算单元1207还可接收时频逆变换单元1206转化后的时域信号E’t(j,l)，并根据该频域信号的一个或多个特征值来确定第二外差频率值△f’＝function(△f,PSD,SNR,…)，其中，上述频域信号的特征值包括：频域信号的PSD,SNR,DR,DZ等。
下面将结合图4对该频率自适应调节模块130内的信号生成模块400的结构原理进行详细说明。图4示出了本申请实施例提供的外差相干型OTDR装置内信号生成模块400的结构示意图。如图4所示，该信号生成模块400包括数字信号产生单元4010、第一数模转换单元4011、信号放大单元4012、信号耦合单元4013和电光调制器4014。其中，该信号生成模块400还可包括光电探测单元4015、偏置电压监控单元4016和光脉冲产生单元4017。
数字信号产生单元4010分别与信号反馈控制单元1300的输出端和第一数模转换单元4011的输入端连接。该数字信号产生单元4010用于根据反馈控制单元1300输入的外差频率值来产生数字信号。
在一种实现方式中，数字信号产生单元4010接收信号反馈控制单元1300提供的第二外差频率值，该数字信号产生单元4010根据该第二外差频率值确定第一数字信号，并将该第一数字信号发送至第一数模转换单元4011。
第一数模转换单元4011分别与数字信号产生单元4010的输出端和信号放大单元4012的输入端连接。该第一数模转换单元4011用于将输入的数字信号转换成模拟电信号。
在一种实现方式中，第一数模转换单元4011将数字信号产生单元4010产生的第一数字信号转换成第二电信号。
信号放大单元4012分别与第一数模转换单元4011的输出端和信号耦合单元4013的输入端连接。该信号放大单元4012用于对输入的模拟电信号进行放大。
在一种实现方式中，信号放大单元4012可对第一数模转换单元4011产生的第二电信号进行放大处理，并生成第三电信号。
信号耦合单元4013分别与电光调制器4014的输入端、信号放大单元4012的输出端和偏置电压监控单元4016的输出端连接。该信号耦合单元4013用于将放大后的模拟电信号和偏置电压合路并输入至光电光调制器4014中。
电光调制器4014分别与分光器110的第一端口、信号耦合单元3013的输出端和光脉冲产生单元4017输入端连接。该电光调制器4014用于将输入的模拟电信号调制到光载波上，并输出为光信号至光脉冲产生单元。
在一种实现方式中，电光调制器4014可对第二光信号进行调制并输出至光脉冲产生单元，该电光调制器4014还可以将信号耦合单元4013输入的第三电信号转换成第八光信号。
可选地，电光调制器4014可包用以下调制器进行替换，例如，声光调制器(Acousto-Optic Modulator,AOM)、半导体光放大器(Semiconductor Optical Amplifier,SOA)、电吸收调制器(Electro-Absorption Modulator,EAM)、马赫-曾德尔调制器(Mach-Zehnder Modulator,MZM)等，本申请对此不做限定。
可选地，该信号生成模块400还包括光脉冲产生单元4017。该光脉冲产生单元4017与电光调制器4014的输出端连接，用于对电光调制器4014输入的光信号进行处理并产生脉冲光信号。
示例性地，该光脉冲产生单元4017可在一个测试周期内生成一个脉冲信号，或者在一个测试周期内生成固定的脉宽和占空比的多个重复的脉冲信号。
可选地，该信号生成模块400还包括光电探测单元4015。
光电探测单元4015分别与偏置电压监控单元4016的输入端和电光调制器4014的输出端连接，该光电探测单元3015用于对调制后的光信号进行检测。
在一种实现方式中，光电探测单元4015可对电光调制器4014输出的第二光信号或第八光信号进行检测。
可选地，该信号生成模块400还包括偏置电压监控单元4016。
偏置电压监控单元4016分别与信号耦合单元4013的输入端和光电探测单元4015的输出端连接。该偏置电压监控单元4016用于根据光电探测单元4015的检测结果来反馈偏置电压，并对该偏置电压进行锁定。
在一种实现方式中，偏置电压监控单元4016可根据光电探测单元4015对电光调制器4014输出的第二光信号或第八光信号的检测结果来确定偏置电压，还用于对该偏置电压锁定。
图5示出了本申请提供的一种传输信号的方法的一例示意性流程框图。
S501，生成并发送第一光信号。
可选地，该第一光信号可用于指示经激光发射模块产生的连续光信号，也可用于指示频率自适应调节模块根据上一次电信号的外差频率值和该电信号的一个或多个特征值生成的连续光信号。
在一种实现方式中，经激光发射模块产生的连续光信号通过环形器第一端口输入，从环形器的第三端口输出至被测光纤上。
S502，接收第二光信号，该第二光信号包括第一光信号的反射和散射信号。
具体地，第二光信号可用于指示激光发射模块初次发射激光时经分光器产生的本振光信 号与环形器第三端口输出的光信号经接收模块混频调制后产生的电信号。该第二光信号还可用于指示在频率自适应调整过程中信号生成模块生成并发送的光信号经待测光纤链路反射或散射回的光信号和分光器产生的本振光信号混频处理后产生的光信号。
具体地，该第二光信号用于指示第一光信号在被测光纤上反射或散射回的光信号与第一光信号经过分光器分出的本振光信号进行耦合后产生的光信号。
可选地，该第二光信号还用于指示在OTDR装置中预设定的光信号。
S503，将第二光信号转换成第一电信号；
在一种实现方式中，在接收模块中的光电探测器将该第二光信号转换成第一电信号。
S504，确定第一电信号的第一外差频率值。
在一种实现方式中，信号反馈控制模块获取接收模块发送的第一电信号，并对该第一电信号的外差频率值进行确定。
S505，根据第一电信号的第一外差频率值和该第一电信号的一个或多个特征值，确定第二外差频率值。
可选地，第一电信号可用于指示接收模块发送至频率自适应调节模块的电信号。
在一种实现方式中，信号反馈控制模块根据第一电信号的第一外差频率值和该第一电信号的一个或多个外差频率值来确定该第二外差频率值。
其中，该信号反馈控制模块包括信号检测与计算单元。
具体地，信号检测与计算单元根据第一电信号的第一外差频率值和该第一电信号的一个或多个特征值来确定该第二外差频率值。其中，该第一电信号的特征值包括：PSD、SNR、DR、DZ等。
具体地，在本申请实施例中，信号检测与计算单元可包括模数转换单元、定帧计算单元、时频变换计算单元、下变频计算单元、滤波单元和计算单元。
在一种实现方式中，以第一电信号在不同单元之间的走向为例进行详细说明。模数转换单元接收接收模块发送的第一电信号，并将其转换成长度为N的数字信号Et(i)，其中，i＝1,2,…N；定帧计算单元接收模数转换单元发送的数字信号Et(i)，并将该数字信号Et(i)分割成K组长度均为M的时域信号，每组时域信号的长度相等，且保持和脉冲周期相同。第j组的数字时域信号为Et(j,l)，其中，j＝1,2,…,K，l＝1,2,…,M，且N＝K*M；时频变换计算单元接收定帧计算单元发送的第j组时域信号，并将其转化为频域信号Ef(j,l)，其中，l＝1,2,…,M。应理解，时频变换的方式可以是傅里叶变换计算，即Ef＝F(Et)。依次令j＝1,2,…,K，即执行该步骤K次，可获得K组长度均为M的频域信号Ef(j,l)，其中j＝1,2,…,K，l＝1,2,…,M，且N＝K*M。
可选地，该信号检测与计算单元还包括下变频计算单元。该信号检测与计算单元可将通过时频变换单元得到的频域信号Ef(j,l)转化为下变频后的频域信号Ef_DDC(j,l)，其中l＝1,2,…,M。可依次令j＝1,2,…,K，即执行该步骤K次，可获得K组长度均为M的频域信号Ef_DDC(j,l)，其中j＝1,2,…,K，l＝1,2,…,M，且N＝K*M。
可选地，该信号检测与计算单元还包括滤波单元。该滤波单元可接收下变频计算单元得到的频域信号Ef_DCC(j,l)，并对其进行滤波处理，以滤除带外噪声，滤波后的频域信号为H*Ef_DDC，其中H为滤波函数；计算单元接收滤波单元滤波后的频域信号H*Ef_DDC，并根据该频域信号的至少一个指标确定第二外差频率值△f’＝function(△f,PSD,SNR,…)，其中，上述指标包括：频域信号的PSD,SNR,DR,DZ等。
可选地，该信号检测与计算单元还包括时频逆变换单元。时频逆变换单元可与滤波单元 的输出端和计算单元的输入端连接。该时频逆变换单元用于将通过定帧计算单元得到的时频信号转化为频域信号。
在一种实现方式下，时频逆变换单元可接收滤波单元滤波后的第j组频域信号H*Ef_DDC，并将其转化为时域信号E’t(j,l)，其中l＝1,2,…,M。其中，时频逆变换的方式可以是通过反傅里叶变换进行计算，即Ef＝F-1(Et)；计算单元可接收时频逆变换单元转化后的时域信号E’t(j,l)，并根据该频域信号的至少一个指标确定第二外差频率值△f’＝function(△f,PSD,SNR,…)，其中，上述指标包括：频域信号的PSD,SNR,DR,DZ等。
可选地，反馈控制模块还包括判决单元。该判决用于对信号检测与计算单元计算出的第二外差频率值进行判决。
在一种实现方式中，判决单元可接收信号检测与计算单元发送的第二外差频率值，并对其进行判决。若第一电信号的第一外差频率值与第二外差频率值的差值的绝对值大于判决阈值，则将该第二外差频率值发送至信号生成模块进行处理；若第一电信号的第一外差频率值与第二外差频率值的差值的绝对值小于等于判决阈值，则保留该第一电信号的第一外差频率值，并将该第一电信号输出至处理模块进行处理。
应理解，上述判决阈值可以根据实际场景需求进行设定，例如，判决阈值可以设置为1MHz，本申请对此不做限定。
S506，根据第二外差频率值生成第三光信号。
在一种实现方式中，第三光信号用于指示信号生成模块根据信号反馈控制模块发送的第二外差频率值生成第三光信号。
其中，该信号生成模块可包括数字信号产生单元、第一数模转换单元、信号放大单元、信号耦合单元和调制单元。
可选地，信号生成模块还可包括该光电探测单元和偏置电压监控单元。
在一种实现方式中，数字信号产生单元接收信号反馈控制模块发送的第二外差频率值，并根据该第二外差频率确定第二数字信号，并将该第二数字信号发送至第一数模转换单元，其中，该第二数字信号具有第二外差频率值的信号特征；第一数模转换单元接收数字信号产生单元发送的第一数字信号，并将该第一数字信号转换成第二电信号；信号放大单元接收第一数模转换单元产生的第二电信号并对该模拟电信号进行放大处理并产生第三电信号；信号耦合单元接收信号放大单元放大处理处理后的第三电信号，并将该模拟电信号和偏置电压合路并输入至光电调制单元中；调制单元接收信号耦合单元输入的第三电信号，并将该第三电信号转换成第三光信号。
可选地，光电探测单元可对调制单元输出的光信号进行检测；偏置电压监控单元用于针对光电探测单元的检测结构来反馈偏置电压，并对该偏置电压进行锁定。
图6本申请实施例提供一例OTDR系统中的外差频率值的计算方法的流程框图。如图6所示该方法包括以下步骤：
S601，设定初始外差频率值Δf0。
示例性的，作为实例而非限定，本申请实施例的初始外差频率值可以为10MHz。
S602，以固定的频率逐步增加外差频率值Δf。
在一种实现方式中，以固定的频率，逐步增加外差频率值，并在每个外差频率值Δf下发送设置好的脉冲次数，对其相应时域信号Et进行采集记录，随后利用傅里叶变换将其转换成频域信号Ef。
其中，作为实例而非限定，本申请实施例中步进的固定频率可设定为30MHz，脉冲次数 可设置为4096次。
S603，当外差频率值Δf大于阈值时，停止调整外差频率值。
具体地，上述阈值可为BW6dB，该BW6dB为接收端为6dB时的模拟带宽值，该值对应于峰值功率的25％。
应理解，上述阈值可以根据实际需求进行设定，本申请实施例对此不做限定。
S604，计算不同外差频率值下对应的SNR值。
其中，初始外差频率值Δf0对应的SNR值为SNR0。
S606，选取满足SNR阈值的数值最大的外差频率值Δf作为输出的外差频率值Δf1。
在一种实现方式中，该Δf1的SNR值满足：SNR≥SNR0-Δ0(dB)，其中，Δ0＝1.5(dB)，在上述条件下选取数值最大的外差频率值作为输出的外差频率值。
根据本申请提供的上述技术方案，在OTDR系统中采用逐步递增的外差频率值来计算输出外差频率值的方法，通过自适应优化外差频率值，可达到基于当前设备模拟带宽限制下的最优系统性能，能够有效提升抗光纤链路反射能力，减小衰减盲区的影响，并且，还可以平衡OTDR系统的动态范围与衰减盲区。
图7是本申请实施例提供的一种基于φ-OTDR系统的动态调整外差频率值的流程框图。如图7所述，该外差频率值的动态调整方法包括：
S701，初始化φ-OTDR系统。
S702，在初始条件下，计算出初始外差频率值A。
S703，检测初始外差频率值下被测光纤上不同距离上的SNR值。
S704，如果满足SNR值小于SNR阈值，则需调整外差频率值A，并将调整后的外差频率值B输入至S703，再次对调整后的外差频率值B对应的SNR值进行计算。
示例性地，若SNR＜SNRth，则需调整外差频率值A，该外差频率值B可为Δf′＝a×Δf，其中Δf′为调整后的外差频率值，Δf为调整前的外差频率值，a为常系数，本申请实施例对此不做限定。
应理解，上述SNR阈值可以根据实际需求进行设定，本申请实施例对此不做限定。
S705，如果满足SNR值大于等于SNR阈值，则对φ-OTDR系统时延后回到S703再次对该外差频率值下所有距离上的SNR值进行检测。
示例性地，若SNR≥SNRth，则将φ-OTDR系统延时100ms后回至S703，再次对该外差频率值下不同检测距离上的SNR值进行计算。
应理解，在上述初始外差频率值条件下，φ-OTDR系统对所有距离上的SNR值进行检测，当在某处距离的衰落点低于相位解调门限时，即当信号的信噪比低于门限值时，难以将有用的信号从中分离出来，而当信号的信噪比提升到门限值之上时，才能将该有用的信号分离出来。若存在某一距离下的SNR值长期低于解调门限值以下，易导致在特定区域形成相干衰减盲区，使得φ-OTDR系统的测量精度下降，严重降低φ-OTDR系统的检测性能。
其中，在OTDR分布式光纤链路中的活动连接器、机械接头等特征点产生反射引起的OTDR系统接收端饱和而带来的一系列“盲点”称之为盲区。光纤中由于接入活动连接器而引起激光脉冲反射峰，从激光脉冲反射峰的起始点到可以识别的其他时间点之间的距离，称为光脉冲衰减盲区。
为了提升φ-OTDR系统的测量精度，采用了上述自适应调整外差频率值的方法，对处于低于相位解调门限的外差频率值进行调整，使得这一距离上的测量精度得到提升，避免因为出现盲区而影响φ-OTDR系统的检测性能。但同时，与该处距离相邻距离处的SNR值会因外 差频率值的变动导致其SNR值低于解调门限值，需要对改变不同距离处的外差频率值进行多次动态调整，避免特定距离长期处于衰减盲区限制φ-OTDR系统的检测精度。
根据本申请提供的上述技术方案，在φ-OTDR系统中通过判决反馈的方式实现对外差频率值的自适应调整，从而可以避免特定距离长期处于相干衰落点上而无法解调相位，即可有效避免在特定距离处形成相干衰减盲区，从而提升φ-OTDR系统的全光纤链路性能，并进一步提升该φ-OTDR系统的检测性能。
上文结合图1至图7，详细描述了本申请的基于光时域反射仪OTDR的自适应调整外差频率值的方法侧实施例，下面将结合图8，详细描述本申请的基于光时域反射仪OTDR的自适应调整外差频率值的装置侧。应理解，装置侧实施例的描述与方法侧实施例的描述相互对应，因此，未详细描述的部分可以参见前面的方法侧实施例。
图8是本申请实施例提供的通讯装置的示意性框图。如图8所示，该通信装置可包括：接收单元810、发送单元820与处理单元830。
应理解，该通信装置800可以包括用于执行图5中的方法500中各种方法的单元。并且，该通信装置800中的各单元和上述其它操作和/或功能分别为了实现图5中的方法500的相应流程。
示例性地，该发送单元810，用于发送第一光信号。
发送单元810，还用于发送第三光信号。
接收单元820，用于接收第二光信号，其中，该第二光信号包括第一光信号的反射和散射信号。
处理单元830，用于将第二光信号转换成第一电信号。
处理单元830，还用于根据第一电信号的第一外差频率值和该第一电信号的一个或多个特征值确定第二外差频率值，其中，该第一电信号的特征值包括：功率谱密度、信噪比、动态范围、盲区。
可选地，处理单元830还用于根据该第二外差频率值生成第三光信号。
可选地，处理单元830还用于将第一电信号转换为第一数字信号，其中该第一电信号可转换为长度为N的数字信号Et(i),其中i＝1,2,…N；将该第一数字信号转换为第一时域信号，其中，该第一时域信号为K组长度为M的时域信号，每组时域信号的长度相等，且该第一时域信号的长度保持和脉冲周期相同；将第一时域信号转换成第一频域信号，其中，该第一频域信号是由第一时域信号经过傅里叶变换计算得到的；将第一频域信号转化为下变频处理后的第二频域信号；对该第二频域信号进行滤波处理，得到第三频域信号；以及根据该第三频域信号的一个或多个特征值确定第二外差频率值。
可选地，处理单元830还用于将第三频域信号转换为第二时域信号；以及根据第二时域信号的一个或多个特征确定第二信号的第二外差频率值。
可选地，处理单元830还用于在根据第一电信号的第一外差频率值和该第一电信号的一个或多个特征值确定第二外差频率值之前，对该第外差频率值进行判决，其中，当该第一电信号的第一外差频率值与第二外差频率值的差值的绝对值大于判决阈值时，发送该第二外差频率值。
可选地，处理单元830还用于根据该第二外差频率值确定第二数字信号，其中，该第二数字信号具有第二外差频率值的信号特征；将第二数字信号转换成第二电信号；将第二电信号进行放大处理，得到第三电信号；将第三电信号和偏置电压合路输入至光电调制单元中；将第三电信号转换为第三光信号。
可选地，处理单元830还用于对第三光信号进行检测；根据第三光信号的检测结果确定该偏置电压，并对该偏置电压进行锁定以固定调整后的第二外差频率值。
还应理解，该通信装置800中的处理单元830可通过至少一个处理器实现。
还应理解，该通信装置800中的处理单元830可以通过该芯片或芯片系统上集成的处理器、微处理器或集成电路等实现。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的系统、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅是示意性的，例如，所述单元的划分，仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
在本说明书中使用的术语“部件”、“模块”、“系统”等用于表示计算机相关的实体、硬件、固件、硬件和软件的组合、软件、或执行中的软件。例如，部件可以是但不限于，在处理器上运行的进程、处理器、对象、可执行文件、执行线程、程序和/或计算机。通过图示，在计算设备上运行的应用和计算设备都可以是部件。一个或多个部件可驻留在进程和/或执行线程中，部件可位于一个计算机上和/或分布在2个或更多个计算机之间。此外，这些部件可从在上面存储有各种数据结构的各种计算机可读介质执行。部件可例如根据具有一个或多个数据分组(例如来自与本地系统、分布式系统和/或网络间的另一部件交互的二个部件的数据，例如通过信号与其它系统交互的互联网)的信号通过本地和/或远程进程来通信。
可以理解的是，本申请的实施例中的处理器可以是中央处理单元(Central Processing Unit，CPU)，还可以是其它通用处理器、数字信号处理器(Digital Signal Processor，DSP)、专用集成电路(Application Specific Integrated Circuit，ASIC)、现场可编程门阵列(Field Programmable Gate Array，FPGA)或者其它可编程逻辑器件、晶体管逻辑器件，硬件部件或者其任意组合。通用处理器可以是微处理器，也可以是任何常规的处理器。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。
所述功能如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施例所述方法的全部或部分步骤。而前述的存储 介质包括：U盘、移动硬盘、只读存储器(Read-Only Memory，ROM)、随机存取存储器(Random Access Memory，RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
在本申请的各个实施例中，如果没有特殊说明以及逻辑冲突，不同的实施例之间的术语和/或描述具有一致性、且可以相互引用，不同的实施例中的技术特征根据其内在的逻辑关系可以组合形成新的实施例。
应理解，在本申请实施例中，编号“第一”、“第二”…仅仅为了区分不同的对象，比如为了区分不同的网络设备，并不对本申请实施例的范围构成限制，本申请实施例并不限于此。
在本申请中，“用于指示”可以包括用于直接指示和用于间接指示。当描述某一指示信息用于指示A时，可以包括该指示信息直接指示A或间接指示A，而并不代表该指示信息中一定携带有A。
此外，具体的指示方式还可以是现有各种指示方式，例如但不限于，上述指示方式及其各种组合等。各种指示方式的具体细节可以参考现有技术，本文不再赘述。由上文所述可知，举例来说，当需要指示相同类型的多个信息时，可能会出现不同信息的指示方式不相同的情形。具体实现过程中，可以根据具体的需要选择所需的指示方式，本申请实施例对选择的指示方式不做限定，如此一来，本申请实施例涉及的指示方式应理解为涵盖可以使得待指示方获知待指示信息的各种方法。
还应理解，在本申请的各种实施例中，上述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本申请实施例的实施过程构成任何限定。
还应理解，在本申请中，“当…时”、“若”以及“如果”均指在某种客观情况下网元会做出相应的处理，并非是限定时间，且也不要求网元实现时一定要有判断的动作，也不意味着存在其它限定。
还应理解，在本申请各实施例中，“A对应的B”表示B与A相关联，根据A可以确定B。但还应理解，根据A确定B并不意味着仅仅根据A确定B，还可以根据A和/或其它信息确定B。
还应理解，本文中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
本申请中出现的类似于“项目包括如下中的一项或多项：A，B，以及C”表述的含义，如无特别说明，通常是指该项目可以为如下中任一个：A；B；C；A和B；A和C；B和C；A，B和C；A和A；A，A和A；A，A和B；A，A和C，A，B和B；A，C和C；B和B，B，B和B，B，B和C，C和C；C，C和C，以及其他A，B和C的组合。以上是以A，B和C共3个元素进行举例来说明该项目的可选用条目，当表达为“项目包括如下中至少一种：A，B，……，以及X”时，即表达中具有更多元素时，那么该项目可以适用的条目也可以按照前述规则获得。
可以理解的是，在本申请的实施例中涉及的各种数字编号仅为描述方便进行的区分，并不用来限制本申请的实施例的范围。上述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (12)

  1. 一种传输信号的方法，其特征在于，包括：
    生成并发送第一光信号；
    接收第二光信号，所述第二光信号包括所述第一光信号的反射和散射信号；
    将所述第二光信号转换成第一电信号；
    确定所述第一电信号的第一外差频率值；
    根据所述第一电信号的第一外差频率值和所述第一电信号的一个或多个特征值确定第二外差频率值，其中，所述第一电信号的特征值包括：功率谱密度、信噪比、动态范围、盲区；
    根据所述第二外差频率值生成并发送第三光信号。
  2. 根据权利要求1所述的方法，其特征在于，所述根据所述第一电信号的第一外差频率值和所述第一电信号的一个或多个特征值确定第二外差频率值，包括：
    将所述第一电信号转换为第一数字信号；
    将所述第一数字信号转换为第一时域信号；
    将所述第一时域信号转换成第一频域信号；
    根据所述第一频域信号的一个或多个特征值确定所述第二外差频率值。
  3. 根据权利要求2所述的方法，其特征在于，所述根据所述第一电信号的第一外差频率值和所述第一电信号的一个或多个特征值确定第二外差频率值，还包括：
    将所述第一频域信号转换为第二时域信号；
    根据所述第二时域信号的一个或多个特征值确定所述第二外差频率值。
  4. 根据权利要求3所述的方法，其特征在于，在所述根据所述第一电信号的第一外差频率值和所述第一电信号的一个或多个特征值确定第二外差频率值之前，还包括：
    对所述第二外差频率值进行判决，其中，当所述第一电信号的第一外差频率值与所述第二外差频率值的差值的绝对值大于判决阈值时，发送所述第二外差频率值。
  5. 根据权利要求1-3中任一项所述的方法，其特征在于，所述根据所述第二外差频率值生成并发送第三光信号，包括：
    根据所述第二外差频率值确定第二数字信号，其中，所述第二数字信号具有所述第二外差频率值的信号特征；
    将所述第二数字信号转换成第二电信号；
    将所述第二电信号进行放大处理，得到第三电信号；
    将所述第三电信号转换为所述第三光信号。
  6. 根据权利要求1-5中任一项所述的方法，其特征在于，所述第一光信号的外差频率值不为零。
  7. 一种传输信号的装置，其特征在于，包括：
    激光发射模块，用于生成并发送第一光信号；
    接收模块，用于接收第二光信号，所述第二光信号包括所述第一光信号的反射和散射信号；
    所述接收模块，还用于将所述第二光信号转换成第一电信号；
    信号反馈控制模块，用于确定所述第一电信号的第一外差频率值；
    信号反馈控制模块，还用于根据所述第一电信号的第一外差频率值和所述第一电信号的 一个或多个特征值确定第二外差频率值，其中，所述第一电信号的特征值包括：功率谱密度、信噪比、动态范围、盲区；
    信号生成模块，用于根据所述第二外差频率值生成并发送第三光信号。
  8. 根据权利要求7所述的装置，其特征在于，所述信号反馈控制模块包括：
    模数转换单元，用于将所述第一电信号转换为第一数字信号；
    定帧计算单元，用于将所述第一数字信号转换为第一时域信号；
    时频变换计算单元，用于将所述第一时域信号转换成第一频域信号；
    计算单元，用于根据所述第一频域信号的一个或多个特征值确定所述第二外差频率值。
  9. 根据权利要求8所述的装置，其特征在于，所述信号反馈控制模块还包括：
    时频逆变换单元，用于将所述第一频域信号转换为第二时域信号。
  10. 根据权利要求9所述的装置，其特征在于，所述信号反馈控制模块还包括：
    判决单元，用于对所述第二外差频率值进行判决，其中，当所述第一电信号的第一外差频率值与所述第二外差频率值的差值的绝对值大于判决阈值时，发送所述第二外差频率值。
  11. 根据权利要求7-10中任一项所述的装置，其特征在于，所述信号生成模块，包括：
    数字信号产生单元，用于根据所述第二外差频率值确定第二数字信号，其中，所述第二数字信号具有所述第二外差频率值的信号特征；
    第一数模转换单元，用于将所述第二数字信号转换成第二电信号；
    信号放大单元，用于将所述第二电信号进行放大处理，得到第三电信号；
    电光调制器，用于将所述第三电信号转换为所述第三光信号。
  12. 一种芯片，其特征在于，包括：处理器，用于从存储器中调用并运行计算机程序，使得安装有所述芯片的通信装置执行如权利要求1至6中任一项所述的方法。
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