WO2022033166A1 - 光纤时域反射仪otdr、测试系统、测试方法及存储介质 - Google Patents

光纤时域反射仪otdr、测试系统、测试方法及存储介质 Download PDF

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Publication number
WO2022033166A1
WO2022033166A1 PCT/CN2021/100624 CN2021100624W WO2022033166A1 WO 2022033166 A1 WO2022033166 A1 WO 2022033166A1 CN 2021100624 W CN2021100624 W CN 2021100624W WO 2022033166 A1 WO2022033166 A1 WO 2022033166A1
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Prior art keywords
signal
otdr
return
test
wavelength
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PCT/CN2021/100624
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English (en)
French (fr)
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张翠红
张建涛
叶知隽
熊涛
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武汉光迅科技股份有限公司
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Priority to US18/020,238 priority Critical patent/US20230275657A1/en
Publication of WO2022033166A1 publication Critical patent/WO2022033166A1/zh

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    • 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]
    • 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
    • H04B10/25—Arrangements specific to fibre transmission
    • H04B10/2575—Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier

Definitions

  • the invention relates to the technical field of optical communication, in particular to an optical fiber time domain reflectometer OTDR, a test system, a test method and a storage medium.
  • Optical Time Domain Reflectometer is an important test instrument in optical fiber communication systems. OTDR uses the backscattered signal generated by Rayleigh scattering and Fresnel reflection when the optical signal is transmitted in the optical fiber, and detects the quality of the optical fiber by analyzing the backscattered signal. OTDRs are widely used in the maintenance of optical fiber communication systems to detect parameters such as optical fiber length and average loss, and to locate faults.
  • Embodiments of the present invention provide an optical fiber time domain reflectometer OTDR, a test system, a test method, and a storage medium.
  • an embodiment of the present invention provides an optical fiber time domain reflectometer OTDR, including:
  • the input terminal is used to receive the input service optical signal
  • a first filter connected to the input end, for filtering interference signals whose wavelength is equal to the test wavelength of the OTDR in the service optical signal
  • the wavelength division multiplexing WDM device has a reflection end, a transmission end and an output end, wherein the reflection end is connected to the first filter, and is used for receiving the service optical signal filtered by the first filter;
  • the OTDR basic unit connected to the transmission end, is used to transmit an OTDR signal equal to the test wavelength and receive a return signal of the OTDR signal, wherein the transmission parameters of the OTDR signal and the return parameters of the return signal , for evaluating the performance index of the optical fiber connected to the output end of the WDM device;
  • the output end of the WDM device is used to output the filtered service optical signal received from the reflection end, output the OTDR signal received from the transmission end, and receive the return from the optical fiber Signal.
  • the device further includes:
  • the second filter is connected to the OTDR basic unit, and is used for filtering the interference signal in the return signal; wherein, the wavelength of the interference signal in the return signal is not equal to the test wavelength.
  • the OTDR basic unit includes:
  • a transmitting module for transmitting an OTDR signal equal to the test wavelength
  • a receiving module for receiving the return signal
  • an optical circulator respectively connected with the transmitting module, the receiving module and the transmission end of the WDM device;
  • the processor is connected to the transmitting module and the receiving module respectively, and is used for obtaining the performance index according to the transmitting parameter of the OTDR signal and the returning parameter of the returning signal.
  • the optical circulator includes:
  • the first port is connected with the transmitting module
  • the second port is connected with the transmission end of the WDM device
  • the third port is connected with the receiving module.
  • an embodiment of the present invention provides an OTDR-based test system, including:
  • a service signal transmitter connected to the input end of the OTDR, for transmitting service optical signals
  • the fiber to be tested is connected to the output end of the OTDR.
  • system further includes:
  • a monitoring device connected to the OTDR, is configured to determine the test wavelength of the OTDR according to the wavelength range of the service optical signal.
  • the monitoring device is also used for:
  • an embodiment of the present invention provides an OTDR-based test method, the method comprising:
  • determining the test wavelength of the OTDR according to the wavelength range of the service optical signal including:
  • the test wavelength of the OTDR is determined according to the wavelength range of the service optical signal and the spectral distribution of the spontaneous emission ASE signal of the EDFA.
  • the receiving and analyzing the return signal of the OTDR signal returned by the fiber to be tested includes:
  • the return parameter includes return time and return power
  • the transmission parameters of the OTDR signal pre-recorded by the processor where the transmission parameters include transmission time and transmission power;
  • the attenuation distribution curve of the fiber to be tested is determined.
  • embodiments of the present invention provide a computer-readable storage medium, where computer-executable instructions are stored in the computer-readable storage medium; after the computer-executable instructions are executed by a processor, one or more of the foregoing can be implemented Test methods provided by technical solutions.
  • the optical fiber time domain reflectometer OTDR, test system and test method provided by the embodiments of the present invention include an input end, a first filter, a wavelength division multiplexing (Wavelength Division Multiplexing, WDM) device, an OTDR basic unit and an output end.
  • the first filter is respectively connected to the input end and the reflection end of the WDM device, and the OTDR basic unit is connected to the transmission end of the WDM device.
  • WDM wavelength division multiplexing
  • the interference signal equal to the test wavelength of the OTDR in the service optical signal is filtered through the first filter; the OTDR signal equal to the test wavelength emitted by the OTDR basic unit and the filtered service optical signal are combined and output by the WDM device, and received The return signal of the OTDR signal is transmitted, and the return signal is transmitted to the OTDR basic unit for analysis and processing.
  • the service optical signal is filtered by the first filter, and the interference signal equal to the test wavelength in the service optical signal is largely eliminated without affecting the service optical signal, so as to ensure that the OTDR test is not transmitted in the optical fiber line. Therefore, it is suitable for performance testing of transmission fibers without interrupting services.
  • integrating the first filter in the OTDR eliminates the need to configure a special power supply and signal interface for the first filter, has strong compatibility with related technologies, is easy to install, and does not add additional equipment or devices.
  • FIG. 1 is a schematic block diagram of a composition structure of an OTDR provided by an embodiment of the present invention
  • Fig. 2 is the attenuation spectrum diagram of the first filter in the OTDR provided by the embodiment of the present invention
  • Fig. 3 is the attenuation spectrum diagram of the WDM device in the OTDR provided by the embodiment of the present invention.
  • Fig. 4 is the attenuation spectrum diagram of the second filter in the OTDR provided by the embodiment of the present invention.
  • FIG. 5 is a schematic block diagram of an optional composition structure of an OTDR provided by an embodiment of the present invention.
  • FIG. 6 is a schematic structural diagram of an OTDR-based test system provided by an embodiment of the present invention.
  • FIG. 7 is an optional schematic structural diagram of an OTDR-based test system provided by an embodiment of the present invention.
  • FIG. 8 is a schematic flowchart of an OTDR-based testing method provided by an embodiment of the present invention.
  • Fig. 9 is the spectral distribution diagram of the ASE signal that EDFA produces.
  • FIG. 10 is a schematic diagram of the flow of an optical signal in an OTDR according to an embodiment of the present invention.
  • first ⁇ second ⁇ third is only used to distinguish similar objects, and does not represent a specific ordering of objects. It is understood that "first ⁇ second ⁇ third" Where permitted, the specific order or sequence may be interchanged to enable the embodiments of the invention described herein to be practiced in sequences other than those illustrated or described herein.
  • optical fiber transmission systems Due to the widespread use of wavelength division multiplexing technology in optical fiber transmission systems, the number of channels is increasing and the transmission distance is getting longer and longer. In order to adapt to longer transmission distances, various optical amplifiers are widely used in optical fiber transmission systems. The spectral distribution of the optical signal in the optical fiber is wide, and the spectral distribution of the noise signal is also relatively wide.
  • OTDR optical fiber line performance detection
  • optical fiber quality detection optical fiber fault point location and other occasions.
  • the OTDR online optical fiber line detection function is gradually integrated into the optical fiber transmission system. Due to the huge amount of data transmitted in the optical fiber line, it is required that the OTDR test cannot interrupt or affect the transmission of business signals.
  • the test principle of OTDR is to use the optical Rayleigh scattering characteristics of the optical fiber and the reflection characteristics of the optical fiber end face to receive the return signal by outputting periodic optical pulses, and to detect the attenuation and connection of the optical fiber line according to the return signal. But the return signal is very weak. Especially the return signal at the far end of the fiber, its power is below -70dBm.
  • FIG. 1 is a schematic block diagram of the composition and structure of an OTDR provided by an embodiment of the present invention.
  • the device includes:
  • the input terminal is used to receive the input service optical signal
  • a first filter connected to the input end, for filtering interference signals whose wavelength is equal to the test wavelength of the OTDR in the service optical signal
  • the wavelength division multiplexing WDM device has a reflection end, a transmission end and an output end, wherein the reflection end is connected to the first filter, and is used for receiving the service optical signal filtered by the first filter;
  • the OTDR basic unit connected to the transmission end, is used to transmit an OTDR signal equal to the test wavelength and receive a return signal of the OTDR signal, wherein the transmission parameters of the OTDR signal and the return parameters of the return signal , for evaluating the performance index of the optical fiber connected to the output end of the WDM device;
  • the output end of the WDM device is used to output the filtered service optical signal received from the reflection end, output the OTDR signal received from the transmission end, and receive the return from the optical fiber Signal.
  • the service optical signal refers to an optical signal used to modulate service data.
  • the filter is an instrument for wavelength selection
  • the filter can select a desired wavelength from a large number of wavelengths, and filter out signals of other wavelengths except the selected wavelength in the optical signal .
  • the filter can be divided into a band-pass filter, a band-stop filter, a low-pass filter, a high-pass filter, and the like.
  • the first filter can be realized by a fiber grating filter or a coating filter; wherein, the fiber grating filter is a kind of optical passive device, which utilizes the thermal sensitivity of the fiber material to generate in the fiber core along the axis of the fiber core. The index of refraction is periodically transformed, thereby forming a narrowband filtering function.
  • the coating filter adopts the method of evaporation coating, and coats the dielectric film with high and low refractive index on the quartz glass substrate according to the design requirements; The coherence is enhanced, the wavelength is filtered out, and the optical signal of the remaining wavelengths is reflected due to the reflection enhanced by the interference, thus realizing the filtering function.
  • the first filter can be a band-stop filter, and the stop-band spectral range can be set according to the test wavelength of the OTDR signal;
  • the signal is greatly attenuated, and the optical signal in the service optical signal whose wavelength range is outside the spectral range of the stop band can pass through the first filter with low loss.
  • FIG. 2 is an attenuation spectrum diagram of a first filter in an OTDR provided by an embodiment of the present invention.
  • the center wavelength of the OTDR signal is ⁇ 0 .
  • ⁇ 0 ⁇ can be considered as the test wavelength.
  • the stopband spectral range of the first filter is ⁇ 0 ⁇ .
  • the first filter will attenuate the optical signal in the wavelength range of ⁇ 0 ⁇ in the service optical signal, and the attenuation value is V2; the optical signal in the service optical signal with a wavelength range outside ⁇ 0 ⁇ passes through the first filter with low loss , the attenuation value is V1.
  • V1 here can be much smaller than V2.
  • V1 is much smaller than V2, which can reduce the loss of the optical signal of the modulated service data as much as possible, and ensure the transmission quality of the optical signal with the modulated service data.
  • the WDM device may be a passive device, which is used to complete multiplexing and demultiplexing of multiple optical signals of different wavelengths.
  • a passive device which is used to complete multiplexing and demultiplexing of multiple optical signals of different wavelengths.
  • a prismatic dispersion type WDM device or a diffractive fiber type WDM device etc.
  • the WDM device includes a reflection end, a transmission end and an output end.
  • the service optical signal is received from the reflection end of the WDM device, and the OTDR signal is received from the transmission end, so that the interference signal equal to the test wavelength in the service optical signal is attenuated by the WDM device, and the OTDR signal is attenuated at the same time.
  • Interfering signals outside the test wavelength range are possible.
  • FIG. 3 is an attenuation spectrum diagram of a WDM device in an OTDR provided by an embodiment of the present invention.
  • the WDM device will attenuate the optical signal whose wavelength range is within ⁇ 0 ⁇ , and the attenuation value is V8; the optical signal whose wavelength range is outside ⁇ 0 ⁇ in the optical signal Low-loss pass through the WDM with an attenuation value of V7.
  • the WDM device will attenuate the optical signal with a wavelength range outside ⁇ 0 ⁇ in the optical signal, and the attenuation value is V6 ;
  • the low-loss signal passes through the WDM, and the attenuation value is V5.
  • the V7 here can be much smaller than the V8. In this way, by processing the large loss of the optical signal in the service optical signal whose wavelength range is within ⁇ 0 ⁇ , the signal that interferes with the test of the OTDR signal in the service optical signal is filtered out.
  • the V5 is much smaller than the V6.
  • V7 is much smaller than V8
  • V5 is much smaller than V6, which can reduce the loss of service optical signals and OTDR signals as much as possible, and ensure that the OTDR test does not affect the normal transmission of service optical signals; at the same time, it ensures that the OTDR test is not affected by the service. influence of light signals.
  • the first filter is respectively connected to the input end of the OTDR and the reflection end of the WDM device; the transmission end of the WDM device is connected to the OTDR basic unit, and the output end of the WDM device is connected to the output end of the OTDR.
  • the OTDR receives the input service optical signal through the input end, and filters the service optical signal through the first filter, and filters the interference signal whose wavelength is equal to the test wavelength of the OTDR in the service optical signal, so as to prevent the service optical signal from affecting the OTDR. test affects.
  • the OTDR basic unit transmits the OTDR signal equal to the test wavelength, and the filtered service optical signal and the OTDR signal output by the OTDR basic unit are combined by the WDM device, and the combined signal is transmitted to the output end of the OTDR for output.
  • the WDM device receives the return signal of the OTDR signal and sends it to the OTDR base unit; the OTDR base unit evaluates the performance index of the optical fiber connected to the OTDR output end according to the return parameters of the received return signal and the transmission parameters of the OTDR signal.
  • the service optical signal (wavelength range ⁇ 0 ⁇ ) filtered by the first filter
  • the external optical signal) is input to the WDM device through the reflection end; after passing through the first filter and the WDM device, the optical signal in the service optical signal whose wavelength range is within ⁇ 0 ⁇ has an attenuation value of V2+V8;
  • the optical signal whose wavelength range is outside ⁇ 0 ⁇ passes through the first filter and the WDM device with low loss, and the attenuation value is V1+V7.
  • the OTDR can greatly reduce the fall of the OTDR in the service optical signal without affecting the service optical signal.
  • the interference signal within the test wavelength range of the OTDR ensures that the test performance of the OTDR is not affected by the service optical signal transmitted in the optical fiber line.
  • the apparatus further includes:
  • a second filter connected to the OTDR basic unit, is used to filter the interference signal in the return signal; wherein, the wavelength of the interference signal in the return signal is not equal to the test wavelength.
  • the second filter can be a band-pass filter, and the pass-band spectral range can be set according to the wavelength of the OTDR test signal;
  • the optical signal is greatly attenuated, and the optical signal whose wavelength range is in the passband spectral range in the return signal can pass through the second filter with low loss.
  • FIG. 4 is an attenuation spectrum diagram of a second filter in an OTDR provided by an embodiment of the present invention.
  • the center wavelength of the test wavelength of the OTDR is ⁇ 0 .
  • the passband spectral range of the second filter is ⁇ 0 ⁇ .
  • the second filter will attenuate the optical signal whose wavelength range is outside ⁇ 0 ⁇ in the return signal, and the attenuation value is V4; the optical signal in the return signal whose wavelength range is within ⁇ 0 ⁇ passes through the second filter with low loss and attenuates The value is V3.
  • V4 here can be much smaller than V3.
  • V4 is much smaller than V3, which can reduce the interference of the reverse Rayleigh scattering signal of the service optical signal to the return signal as much as possible, and ensure that the OTDR test performance is not degraded.
  • the second filter is connected to the OTDR basic unit, and is used for filtering out the interference signal in the return signal.
  • the OTDR receives the return signal of the OTDR signal through the output end, and the WDM device receives the return signal through the output end; and the transmission end transmits the return signal to the second filter, and the second filter filters the return signal and transmits it. to the OTDR base unit.
  • the test wavelength of the OTDR is ⁇ 0 .
  • the interference signal in the return signal (optical signal outside the wavelength range of ⁇ 0 ⁇ ) is filtered out by the second filter.
  • the optical signal whose wavelength range is outside ⁇ 0 ⁇ in the return signal has an attenuation value of V6+V4; the optical signal whose wavelength range is within ⁇ 0 ⁇ in the return signal passes through with low loss WDM device and second filter, the attenuation value is V5+V3.
  • interference signals outside the test wavelength range of the OTDR in the return signal of the OTDR are further filtered out by the second filter.
  • the OTDR base unit includes:
  • a transmitting module for transmitting an OTDR signal equal to the test wavelength
  • a receiving module for receiving the return signal
  • an optical circulator respectively connected with the transmitting module, the receiving module and the transmission end of the WDM device;
  • the processor is respectively connected with the transmitting module and the receiving module, and is used for obtaining the performance index according to the transmitting parameter of the OTDR signal and the returning parameter of the returning signal.
  • the emission module is an optoelectronic device used for electro-optical conversion; for example, a pulsed laser or the like.
  • the emitting module includes a light emitting device and a driving circuit; after receiving the electrical signal, the driving circuit drives the light emitting device to send an optical signal of a set wavelength according to the received electrical signal.
  • the receiving module is an optoelectronic device used for photoelectric conversion.
  • the receiving module includes a light receiving device, a booster circuit, and a microprocessor (Microcontroller Unit, MCU).
  • the light receiving device is used to convert the light signal into an electrical signal, such as an avalanche diode, etc.
  • the boost circuit is used to provide a bias voltage for the light receiving device
  • the MCU is used to control the voltage output by the boost circuit.
  • the optical circulator is a multi-port optical device with non-reciprocal characteristics. It includes at least three ports, and a connected annular channel is formed between the ports of the optical circulator.
  • a connected annular channel is formed between the ports of the optical circulator.
  • the transmission direction of the circulator is: from the first port connected with the transmitting module to the second port connected with the WDM device; and then from the second port to the third port connected with the receiving module.
  • the processor is an execution unit for information processing and program operation, and is used to process and analyze the received optical signal, thereby detecting and obtaining parameters such as performance indicators of the optical fiber.
  • the optical circulator is respectively connected with the transmitting module, the receiving module and the transmission end of the WDM device; the processor is respectively connected with the transmitting module and the receiving module.
  • the processor drives the transmitting module to transmit the OTDR signal, the OTDR signal is transmitted to the transmission end of the WDM device through the optical circulator, and the OTDR signal and the filtered service optical signal are combined and output through the WDM device.
  • the WDM device transmits the received return signal of the OTDR signal to the receiving module through the optical circulator. After the receiving module receives the return signal, it sends the return parameter of the return signal to the processor, so that the processor can follow the return parameter of the return signal. And the emission parameters of the OTDR signal to evaluate the performance index of the fiber.
  • the return parameters of the return signal include: return time and return power; the transmission parameters of the OTDR signal include: transmission time and transmission power.
  • the processor records the return time and return power of the return signal, and according to the transmission time and transmission power of the OTDR signal, the time difference between the return time and the transmission time, and the transmission of light in the optical fiber speed, calculates the actual length of the fiber. According to the return power and return time, draw the attenuation profile of the fiber.
  • the OTDR signal is transmitted through the OTDR basic unit, and the return signal of the OTDR signal is received.
  • the performance index of the optical fiber is evaluated, and the test of the optical fiber is completed.
  • the optical circulator includes:
  • the first port is connected with the transmitting module
  • the second port is connected with the transmission end of the WDM device
  • the third port is connected with the receiving module.
  • the optical circulator is respectively connected with the transmitting module, the WDM device and the receiving module; wherein, the first port is connected with the transmitting module, the second port is connected with the transmission end of the WDM device, and the third port is connected with Receive module connection.
  • the OTDR signal emitted by the transmitter module is sent to the transmission end of the WDM device, and combined with the service optical signal for output; and the return signal sent by the WDM device is sent to the receiving module to evaluate the optical fiber according to the return parameters of the return signal. Performance.
  • the performance index includes but is not limited to at least one of the following: the actual length of the optical fiber, the attenuation coefficient of the optical fiber, the loss distribution curve of the optical fiber, and the position of the fault point of the optical fiber.
  • FIG. 5 is a schematic block diagram of an optional composition structure of an OTDR provided by an embodiment of the present invention.
  • the second filter is connected in series between the third port of the optical circulator and the receiving module, and is used to filter out the interference signal of the return signal.
  • the service optical signal and the OTDR signal when transmitted in the same direction, the service optical signal will also generate a Rayleigh scattering signal during the transmission process, and return to the WDM for transmission.
  • the return signal received by the WDM device includes both the return signal of the OTDR signal and the return signal of the service optical signal; the return signal of the service optical signal will cause interference to the OTDR test.
  • the return signal of the service optical signal in the return signal is filtered out by the second filter, so as to reduce the interference of the return signal of the service optical signal to the return signal of the OTDR signal in the transmission system.
  • the optical circulator transmits the return signal sent by the WDM device to the second filter, and the second filter filters out the interference signal in the return signal; the second filter transmits the filtered return signal to the receiving module , to evaluate the performance index of the fiber according to the return parameters of the returned signal.
  • the OTDR signal emitted by the transmitting module is transmitted to the transmission end of the WDM device through the optical circulator; and the return signal of the OTDR signal received by the WDM device is transmitted to the receiving module, so that the separation of forward/reverse transmission is realized.
  • FIG. 6 is a schematic structural diagram of an OTDR-based test system provided by an embodiment of the present invention.
  • the system includes:
  • a service signal transmitter connected to the input end of the OTDR, for transmitting service optical signals
  • the fiber to be tested is connected to the output end of the OTDR.
  • the OTDR is the OTDR in the aforementioned FIG. 1 or FIG. 5 .
  • the service signal transmitter is connected to the input end of the OTDR, and the output end of the OTDR is connected to the fiber to be tested.
  • the OTDR receives the service optical signal transmitted by the service signal transmitter through the input end, and filters the service optical signal through the first filter to filter out the interference signal whose wavelength is equal to the test wavelength of the OTDR in the service optical signal.
  • the OTDR basic unit of the OTDR transmits the OTDR signal and transmits it to the WDM device; the filtered service optical signal and the OTDR signal are combined and output to the output end of the OTDR through the WDM device, so as to be transmitted to the output end connected to the output end. in the fiber under test.
  • FIG. 7 is an optional schematic structural diagram of an OTDR-based test system provided by an embodiment of the present invention.
  • the system also includes:
  • a monitoring device connected to the OTDR, is configured to determine the test wavelength of the OTDR according to the wavelength range of the service optical signal.
  • the monitoring device is connected to the processor of the OTDR.
  • the test wavelength of the OTDR is set by the monitoring device, and the test wavelength information is sent to the processor, and the processor drives the transmitting module of the OTDR to transmit the OTDR signal corresponding to the test wavelength.
  • the monitoring device may determine the test wavelength of the OTDR according to the wavelength range of the service optical signal.
  • the test wavelength of the OTDR should be determined according to the wavelength range of the service optical signal transmitted by the optical fiber.
  • the test wavelength of the OTDR should avoid the DWDM standard wavelength range, the OSC wavelength range, and the Raman pump wavelength range, etc., which are not specifically limited here.
  • the test wavelength can also choose a wavelength range with a low fiber attenuation coefficient.
  • 850 nm, 1550 nm, etc. are not specifically limited here.
  • the monitoring device determines the test wavelength of the OTDR according to the wavelength of the service optical signal, thereby ensuring that the test performance of the OTDR is not affected by the service optical signal transmitted in the optical fiber line.
  • the monitoring device is also used for:
  • the processor after receiving the return parameter of the return signal, evaluates the performance index of the fiber to be tested according to the return parameter of the return signal and the emission parameter of the OTDR signal; and calculates the performance index parameter of the fiber to be tested Sent to monitoring equipment for display.
  • the return parameters of the return signal include: return time and return power; the transmission parameters of the OTDR signal include: transmission time and transmission power.
  • the processor calculates the actual length of the fiber to be measured by the time difference between the return time and the launch time, and the transmission speed of light in the fiber. According to the return power and return time, draw the attenuation profile of the fiber. And send the actual length and attenuation distribution curve of the fiber to be tested to the monitoring equipment for display.
  • the performance indicators of the optical fiber to be tested are evaluated, and the performance indicators of the optical fiber to be tested are more intuitively displayed by the monitoring equipment, thereby facilitating the maintenance of the optical fiber transmission line.
  • FIG. 8 is a schematic flowchart of an OTDR-based test method provided by an embodiment of the present invention.
  • the method includes:
  • Step 801 Determine the test wavelength of the OTDR according to the wavelength of the service optical signal
  • Step 802 According to the test wavelength, transmit an OTDR signal to the fiber to be tested;
  • Step 803 Filter out the interference signal equal to the test wavelength in the service optical signal
  • Step 804 Receive the return signal of the OTDR signal returned by the fiber to be tested; wherein, the emission parameters of the OTDR signal and the return parameter of the return signal are used to evaluate the optical fiber connected to the output end of the WDM device connection. Performance.
  • the OTDR includes an input end, a first filter, a WDM device, an OTDR basic unit, and an output end.
  • the input end is connected to the first filter
  • the first filter is connected to the reflection end of the WDM device
  • the transmission end of the WDM device is connected to the OTDR basic unit
  • the output end of the WDM device is connected to the output end of the OTDR.
  • the test wavelength of the OTDR is determined according to the wavelength of the service optical signal, so as to ensure that the test performance of the OTDR is not affected by the service optical signal transmitted in the optical fiber line.
  • the wavelength of the service optical signal and the fiber attenuation coefficient should be comprehensively considered, and the wavelength with the low fiber attenuation coefficient should be selected to achieve a longer test distance.
  • 850 nm, 1550 nm, etc. are not specifically limited here.
  • the test wavelength of the OTDR should avoid the DWDM standard wavelength range, the OSC wavelength range, and the Raman pump wavelength range, etc., which are not specifically limited here.
  • the processor of the OTDR drives the transmitting module of the OTDR basic unit to transmit the OTDR signal corresponding to the test wavelength according to the test wavelength, and the OTDR signal is transmitted to the WDM device through the optical circulator, and is transmitted by the WDM device Send the OTDR signal to the fiber under test connected to the OTDR output.
  • step 803 of this embodiment the service optical signal is received through the input end of the OTDR, and the interference signal equal to the test wavelength in the service optical signal is filtered out by the first filter; the filtered service optical signal is transmitted to the WDM
  • the WDM device sends the service optical signal to the fiber under test connected to the output end of the OTDR.
  • the application of various amplifiers in the optical transmission system leads to the widespread existence of noise signals (such as ASE signals) in the optical fiber line, and the spectral distribution is wide; the noise signals seriously interfere with the test performance of the OTDR.
  • the first filter filters the noise signal whose wavelength is equal to the test wavelength in the service optical signal, so as to reduce the influence of the service optical signal in the optical fiber line on the OTDR test.
  • the first filter filters out the interference signal whose wavelength is equal to the test wavelength of the OTDR in the service optical signal, so that the OTDR can greatly reduce the amount of the service optical signal falling on the OTDR without affecting the service optical signal.
  • Test interference signals in the wavelength range to ensure that the test performance of the OTDR is not affected by the business optical signals transmitted in the optical fiber line.
  • the step 801 may include: when the service optical signal is an optical signal amplified by an erbium-doped fiber amplifier EDFA, according to the wavelength range of the service optical signal and the spectrum of the spontaneous emission ASE signal of the EDFA distribution to determine the test wavelength of the OTDR.
  • the EDFA includes an erbium-doped optical fiber, a pump light source, a coupler, an optical isolator, and an optical filter; when the EDFA amplifies the power of a service optical signal, amplifier ASE noise will also be generated.
  • random incoherent spontaneous emission of excited particles is also generated as the activated example returns from the excited state to the ground state and amplifies the optical signal; this spontaneous emission can be in any direction and can be Causes further stimulated emission and can be amplified. Therefore, the frequency band of ASE is very wide and can occupy the entire gain bandwidth.
  • the wavelength range of the lower power of the ASE signal is determined to avoid the influence of the ASE signal of the EDFA amplifier on the test of the OTDR.
  • FIG. 9 is a spectral distribution diagram of an ASE signal generated by an EDFA, wherein FIG. 9 includes four spectral distribution curves of the ASE signal under different gains.
  • the power of the ASE of the EDFA starts to drop significantly in the wavelength range below 1528nm and above the wavelength range of 1563nm. Therefore, according to the spectral distribution of the ASE signal, the test wavelength of the OTDR can be selected in the wavelength range with lower ASE power in Figure 9.
  • the test wavelength is lower than 1520nm, or higher than 1600nm, etc.
  • step 804 includes:
  • the transmission parameters of the OTDR signal pre-recorded by the processor where the transmission parameters include transmission time and transmission power;
  • the attenuation distribution curve of the fiber to be tested is determined.
  • the performance index of the fiber to be tested is evaluated through the return parameters of the return signal and the emission parameters of the OTDR signal, thereby ensuring the quality of the fiber transmission line.
  • Embodiments of the present invention further provide a computer storage medium, where a computer program is stored in the computer storage medium. After the computer program is executed by the processor, the data transmission method provided by one or more of the foregoing technical solutions is executed. Execute the method shown in Figure 8.
  • the computer storage medium provided by the embodiment of the present invention includes: a mobile storage device, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, etc. that can store program codes medium.
  • the computer storage medium may be a non-transitory storage medium.
  • the non-transitory storage medium here may also be referred to as a non-volatile storage medium.
  • This example provides an OTDR-based test system that includes:
  • the OTDR includes an input end, a first filter, a WDM device, a second filter and an OTDR basic unit.
  • FIG. 10 is a schematic diagram of the flow of an optical signal in an OTDR according to an embodiment of the present invention.
  • the service optical signal received from the input end is filtered through the first filter; the filtered service optical signal is combined with the OTDR signal transmitted by the OTDR basic unit through the WDM device, and output to the optical fiber at the output end connected to the WDM device.
  • the return signal of the OTDR signal is received by the WDM, and the interference signal in the return signal is filtered out by the second filter, and the filtered return signal is transmitted to the OTDR basic unit to evaluate the performance index of the optical fiber.
  • 1519nm is selected as the test wavelength of the OTDR signal
  • the spectral width of the OTDR signal is set to 1519nm ⁇ 1nm
  • the peak power of the output optical pulse of the transmitting module of the OTDR basic unit of the OTDR is 17dBm
  • the pulse width is 20us.
  • the EDFA gain is 33dB, and the EDFA signal and the OTDR output signal are transmitted in the same direction.
  • the fiber loss coefficient of 1519nm is about 0.2dB/km; the first filter adopts a single-stage coating filter, and the second filter adopts a double-stage coating filter.
  • V1 0.8dB
  • V2 35dB
  • V3 1.6dB
  • V4 70dB
  • V5 0.8dB
  • V6 35dB
  • V7 0.5dB
  • V8 15dB.
  • the power of the ASE signal is about -32.5dBm; while the Rayleigh scattering back signal integration of the continuous optical signal in the transmission fiber is typically -32dB . Therefore, within the wavelength range of 1519nm ⁇ 1nm, after the ASE noise signal of the EDFA passes through the transmission fiber, the power of the backward integrated power at the output end of the OTDR is:
  • Pase_r refers to the integral value of the back Rayleigh scattering power of the ASE signal at the output end of the OTDR within the wavelength range of 1519 nm ⁇ 1 nm.
  • the service optical signal received from the input end of the OTDR is not filtered by the first filter, it is directly input from the reflection end of the WDM, and then output from the output end of the OTDR; within the wavelength range of 1519nm ⁇ 1nm, the ASE noise signal of the EDFA After passing through the transmission fiber, the power of the backward integrated power at the output end of the OTDR is:
  • the Rayleigh scattering coefficient of a pulsed signal in a single-mode fiber is as follows:
  • S is the backscatter capture factor, which is related to the numerical aperture of the fiber type;
  • m 405
  • NA the numerical aperture of the fiber
  • n 0 the refractive index of the fiber
  • ⁇ s the scattering coefficient of the fiber
  • ⁇ the propagation speed of light in the fiber
  • C the transmission speed of light in vacuum
  • n 0 the refractive index of the fiber
  • ⁇ t the width of the light pulse.
  • K ns (dB) refers to the backscattering coefficient of an optical pulse signal with a pulse width of 1 ns at each point on the fiber line.
  • the backscattering coefficient is:
  • K( ⁇ t) refers to the backscattering coefficient of an optical pulse signal with a pulse width of ⁇ tns at each point on the optical fiber line.
  • the peak power of the output pulse of the OTDR is 17dBm, when the pulse width is 20us, the calculated backscattering coefficient is -37dB; when the pulse width is 1us, the calculated backscattering coefficient is -50dB.
  • the attenuation coefficient of the optical signal with a wavelength of 1519nm in the fiber is about 0.2dB/km, and the optical power of the Rayleigh scattered light signal of the OTDR optical pulse signal at 125km returned to the output end of the OTDR is:
  • the backward integrated power of the ASE signal is -79.5dBm, which is only 7.9dB lower than the return signal power of -71.6dBm of the OTDR signal with a pulse width of 20us returned by the fiber at 125km, which is lower than The return signal with a pulse width of 1us is also 5.01dB higher.
  • the backward integrated power of the ASE signal is -114.5dBm, which is much smaller than the return signal power of the OTDR signal with a pulse width of 20us returned by the fiber at 125km -71.6dBm and the return signal with a pulse width of 1us Power -84.6dBm.
  • the function of the second filter is to filter the noise signal outside the test wavelength range in the return signal.
  • the service optical signal in the broad spectral range is transmitted in the same direction as the OTDR signal of the OTDR, and the service optical signal is also transmitted in the same direction. Rayleigh scattering occurs in the process.
  • the typical value of the backward signal integral is -32dB.
  • the reverse Rayleigh scattering of the service optical signal is The power value:
  • the business optical signal returned by Rayleigh scattering is transmitted to the receiving module of the OTDR basic unit after passing through the WDM device and the second filter.
  • the optical power of the business optical signal with a wavelength range of 1519nm ⁇ 1nm is:
  • the return signal is transmitted to the receiving module of the OTDR basic unit, and the optical power of the service optical signal with a wavelength range of 1519nm ⁇ 1nm is:
  • the returned Rayleigh scattering signal of the OTDR signal at the receiving module of the OTDR basic unit is:
  • the second filter plays a key role in filtering the reverse Rayleigh optical signal of the service optical signal. If there is no second filter in the OTDR, the reverse Rayleigh scattering signal power of the service optical signal reaches -44.6dBm, which is much greater than the return signal power of the OTDR signal -74dBm. For the OTDR including the second filter, the reverse Rayleigh scattering signal power of the service optical signal is -114.6dBm, which is much smaller than the return signal power of the OTDR signal.
  • the first filter in the OTDR filters out the interference signal whose wavelength is equal to the test wavelength in the co-direction transmission signal
  • the second filter filters out the reverse Rayleigh scattering signal of the co-direction transmission signal, which greatly reduces the noise in the transmission system.
  • the interference of the service optical signal to the OTDR signal of the OTDR greatly reduces the performance degradation of the online OTDR test system.
  • the disclosed apparatus and method may be implemented in other manners.
  • 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 may be combined, or Can be integrated into another system, or some features can be ignored, or not implemented.
  • the coupling, or direct coupling, or communication connection between the components shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be electrical, mechanical or other forms. of.
  • the unit described above as a separate component may or may not be physically separated, and the component displayed as a unit may or may not be a physical unit, that is, it may be located in one place or distributed to multiple network units; Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.
  • each functional unit in each embodiment of the present invention may all be integrated into one processing module, or each unit may be separately used as a unit, or two or more units may be integrated into one unit; the above-mentioned integration
  • the unit can be implemented either in the form of hardware or in the form of hardware plus software functional units.
  • the aforementioned program may be stored in a computer-readable storage medium, and when the program is executed, execute Including the steps of the above method embodiment; and the aforementioned storage medium includes: a mobile storage device, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk and other various A medium on which program code can be stored.
  • ROM read-only memory
  • RAM random access memory
  • magnetic disk or an optical disk and other various A medium on which program code can be stored.

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Abstract

本发明提供了一种光纤时域反射仪OTDR、测试系统、测试方法及存储介质；包括：输入端，用于接收输入的业务光信号；第一滤波器，与输入端相连，用于过滤业务光信号中波长等于OTDR的测试波长的干扰信号；波分复用WDM器，具有反射端、透射端及输出端；OTDR基本单元，与透射端连接，用于发射等于测试波长的OTDR信号，并接收OTDR信号的返回信号；WDM器的输出端，用于输出从反射端接收的过滤后的业务光信号，并输出从透射端接收的OTDR信号，并接收从光纤返回的返回信号。

Description

光纤时域反射仪OTDR、测试系统、测试方法及存储介质 技术领域
本发明涉及光通信技术领域，尤其涉及一种光纤时域反射仪OTDR、测试系统、测试方法及存储介质。
背景技术
光时域反射仪(Optical Time Domain Reflectometer，OTDR)是光纤通信系统中重要的测试仪器。OTDR是利用光信号在光纤中传输时的瑞利散射和菲涅尔反射所产生的背向散射信号，通过对背向散射信号的分析，检测光纤的质量情况。OTDR被广泛应用于光纤通信系统的维护中，进行光纤长度、平均损耗等参数的检测，并进行故障定位。
在当前的光纤传输线路中，传输数据量越来越大，光纤承载的信息量急剧增加，实时检测和保障光纤线路的良好状况变得越来越重要。OTDR作为光纤线路检测的有效手段，被逐步应用于在线光纤线路中；并且必须在不中断业务的条件下对光纤线路进行定期检测。
发明内容
本发明实施例提供一种光纤时域反射仪OTDR、测试系统、测试方法及存储介质。
本发明实施例的技术方案是这样实现的：
第一方面，本发明实施例提供一种光纤时域反射仪OTDR，包括：
输入端，用于接收输入的业务光信号；
第一滤波器，与所述输入端相连，用于过滤所述业务光信号中波长等于所述OTDR的测试波长的干扰信号；
波分复用WDM器，具有反射端、透射端及输出端，其中，所述反射端与所述第一滤波器连接，用于接收所述第一滤波器过滤后的所述业务光信号；
OTDR基本单元，与所述透射端连接，用于发射等于所述测试波长的OTDR信号，并接收所述OTDR信号的返回信号，其中，所述OTDR信号的发射参数 及所述返回信号的返回参数，用于评估连接在所述WDM器连接的输出端的光纤的性能指标；
所述WDM器的输出端，用于输出从所述反射端接收的过滤后的业务光信号，并输出从所述透射端接收的所述OTDR信号，并接收从所述光纤返回的所述返回信号。
可选地，所述设备还包括：
第二滤波器，与所述OTDR基本单元连接，用于过滤所述返回信号中的干扰信号；其中，所述返回信号中的干扰信号的波长不等于所述测试波长。
可选地，所述OTDR基本单元包括：
发射模组，用于发射等于所述测试波长的OTDR信号；
接收模组，用于接收所述返回信号；
光环形器，分别与所述发射模组、所述接收模组及所述WDM器的所述透射端连接；
处理器，分别与发射模组、接收模组连接，用于根据所述OTDR信号的发射参数及所述返回信号的返回参数得到所述性能指标。
可选地，所述光环形器包括：
第一端口、第二端口及第三端口；
所述第一端口与所述发射模组连接，所述第二端口与所述WDM器的所述透射端连接，所述第三端口与所述接收模组连接。
第二方面，本发明实施例提供一种基于OTDR的测试系统，包括：
如前述一个或多个技术方案所述的OTDR；
业务信号发射器，与所述OTDR的输入端连接，用于发射业务光信号；
待测光纤，与所述OTDR的输出端连接。
可选地，所述系统还包括：
监测设备，与所述OTDR连接，用于根据业务光信号的波长范围，确定所述OTDR的测试波长。
可选地，所述监测设备还用于：
接收并显示所述OTDR输出的所述待测光纤的性能指标。
第三方面，本发明实施例提供一种基于OTDR的测试方法，所述方法包括：
根据业务光信号的波长，确定OTDR的测试波长；
根据所述测试波长，向待测光纤发射OTDR信号；
滤除所述业务光信号中等于所述测试波长的干扰信号；
接收所述待测光纤返回的OTDR信号的返回信号；其中，所述OTDR信号的发射参数及所述返回信号的返回参数，用于评估连接在所述WDM器连接的输出端的光纤的性能指标。
可选地，所述根据业务光信号的波长范围，确定OTDR的测试波长，包括：
当所述业务光信号为经过掺饵光纤放大器EDFA放大的光信号时，根据所述业务光信号的波长范围和EDFA的自发辐射ASE信号的光谱分布，确定OTDR的测试波长。
可选地，述接收并分析所述待测光纤返回的OTDR信号的返回信号，包括：
接收所述OTDR信号的返回信号，记录所述返回信号的返回参数；所述返回参数包括返回时间和返回功率；
获取所述处理器预先记录的所述OTDR信号的发射参数，所述发射参数包括发射时间、发射功率；
根据所述OTDR信号的发射时间和所述返回信号的返回时间，确定所述待测光纤的长度；
根据所述OTDR信号的发射参数和所述返回信号的返回参数，确定所述待测光纤的衰减分布曲线。
第四方面，本发明实施例提供一种计算机可读存储介质，所述计算机可读存储介质存储有计算机可执行指令；所述计算机可执行指令被处理器执行后，能够实现前述一个或多个技术方案提供的测试方法。
本发明实施例提供的光纤时域反射仪OTDR、测试系统及测试方法，OTDR包括输入端、第一滤波器、波分复用(Wavelength Division Multiplexing，WDM)器、OTDR基本单元及输出端。其中，第一滤波器分别与输入端、WDM器的反射端连接，OTDR基本单元与WDM器透射端连接。通过第一滤波器过滤业务光信号中等于所述OTDR的测试波长的干扰信号；通过WDM器将OTDR基本单元发射的等于测试波长的OTDR信号与过滤后的业务光信号合波输出，并接收所述OTDR信号的返回信号，将返回信号传输至OTDR基本单元进行分析、处理。
第一方面，通过第一滤波器对业务光信号进行滤波，在不影响业务光信号的条件下，大幅度消除业务光信号中等于测试波长的干扰信号，确保OTDR的测试不受光纤线路中传输的业务光信号的影响；从而适用于在不中断业务的情况下对传输光纤进行性能检测。
第二方面，将第一滤波器集成在OTDR内，不需要为第一滤波器配置专门 的电源和信号接口，具有与相关技术兼容性强，易于安装，不增加额外的设备或器件的特点。
附图说明
图1是本发明实施例提供的一种OTDR的组成结构方框示意图；
图2是本发明实施例提供的OTDR内第一滤波器的衰减光谱图；
图3是本发明实施例提供的OTDR内WDM器的衰减光谱图；
图4是本发明实施例提供的OTDR内第二滤波器的衰减光谱图；
图5是本发明实施例提供的一种OTDR的一个可选的组成结构方框示意图；
图6是本发明实施例提供的一种基于OTDR的测试系统的结构示意图；
图7是本发明实施例提供的一种基于OTDR的测试系统的一个可选的结构示意图；
图8是本发明实施例提供的一种基于OTDR的测试方法的流程示意图；
图9是EDFA产生的ASE信号的光谱分布图；
图10是本发明实施例提供的OTDR内光信号的流向示意图。
具体实施方式
为了使本发明的目的、技术方案和优点更加清楚，下面将结合附图对本发明作进一步地详细描述，所描述的实施例不应视为对本发明的限制，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其它实施例，都属于本发明保护的范围。
在以下的描述中，涉及到“一些实施例”，其描述了所有可能实施例的子集，但是可以理解，“一些实施例”可以是所有可能实施例的相同子集或不同子集，并且可以在不冲突的情况下相互结合。
在以下的描述中，所涉及的术语“第一\第二\第三”仅仅是是区别类似的对象，不代表针对对象的特定排序，可以理解地，“第一\第二\第三”在允许的情况下可以互换特定的顺序或先后次序，以使这里描述的本发明实施例能够以除了在这里图示或描述的以外的顺序实施。
除非另有定义，本文所使用的所有的技术和科学术语与属于本发明的技术领域的技术人员通常理解的含义相同。本文中所使用的术语只是为了描述本发明实施例的目的，不是旨在限制本发明。
由于光纤传输系统中波分复用技术的广泛使用，通道数越来越多，传输距 离也越来越长。为了适应更长的传输距离，各种光放大器被广泛应用于光纤传输系统中。光纤中的光信号的光谱分布广泛，且噪声信号的光谱分布也比较广泛。
OTDR作为光纤线路性能检测的有效手段，被广泛地应用于光纤质量检测、光纤故障点定位等场合中，OTDR在线光纤线路检测功能逐渐被集成在光纤传输系统中。由于光纤线路中传输的数据量极大，要求OTDR测试不能中断或影响业务信号传输。而OTDR的测试原理是通过输出周期光脉冲的方式，利用光纤中的光瑞利散射特性和光纤端面反射特性，接收返回信号，根据返回信号来检测光纤线路的衰减和连接情况。但返回信号非常微弱。特别是光纤远端的返回信号，其功率达到-70dBm以下。光纤传输系统中各种放大器的应用，导致光纤线路中噪声广泛存在且光谱分布很广。尤其是，当OTDR测试信号与掺饵光纤放大器(Erbium-Doped Fiber Amplifier，EDFA)输出信号共纤同向传输时，EDFA产生的自发辐射(Amplified Spontaneous Emission，ASE)噪声，对OTDR的测试性能产生严重干扰，使OTDR检测动态范围大大降低，OTDR的测试性能劣化量达到10dB以上。
本发明实施例提供一种OTDR，如图1所示，图1是本发明实施例提供的一种OTDR的组成结构方框示意图，所述设备包括：
输入端，用于接收输入的业务光信号；
第一滤波器，与所述输入端相连，用于过滤所述业务光信号中波长等于所述OTDR的测试波长的干扰信号；
波分复用WDM器，具有反射端、透射端及输出端，其中，所述反射端与所述第一滤波器连接，用于接收所述第一滤波器过滤后的所述业务光信号；
OTDR基本单元，与所述透射端连接，用于发射等于所述测试波长的OTDR信号，并接收所述OTDR信号的返回信号，其中，所述OTDR信号的发射参数及所述返回信号的返回参数，用于评估连接在所述WDM器连接的输出端的光纤的性能指标；
所述WDM器的输出端，用于输出从所述反射端接收的过滤后的业务光信号，并输出从所述透射端接收的所述OTDR信号，并接收从所述光纤返回的所述返回信号。
这里，业务光信号是指用于调制有业务数据的光信号。
在本发明实施例中，所述滤波器是用来进行波长选择的仪器，滤波器可以从众多的波长中挑选出所需的波长，滤除光信号中除选定波长外的其他波长的 信号。例如，根据滤波器的选频特性，可分为带通滤波器、带阻滤波器、低通滤波器、高通滤波器等。
需要说明的是，第一滤波器可由光纤光栅滤波器或镀膜滤波器实现；其中，光纤光栅滤波器是一种光无源器件，利用光纤材料的热敏性，在纤芯内产生沿纤芯轴向的折射率周期变换，从而形成的窄带滤波功能。镀膜滤波器是采用蒸发镀膜的方法，在石英玻璃基底上按设计要求镀高、低折射率交臂的介质薄膜；镀膜滤波器利用光的多光束干涉，使某一波长的光信号的透射被相干加强，该波长被滤出，其余波长的光信号由于反射被干涉加强而被反射，从而实现了滤波功能。
在实际应用中，第一滤波器可以为带阻滤波器，阻带光谱范围可根据OTDR信号的测试波长进行设置；通过第一滤波器对业务光信号中波长范围在阻带光谱范围内的光信号进行大幅度衰减，而业务光信号中波长范围在阻带光谱范围外的光信号能低损耗通过第一滤波器。
示例性地，如图2所示，图2是本发明实施例提供的OTDR内第一滤波器的衰减光谱图。其中OTDR信号的中心波长为λ 0。λ 0±Δλ可认为是测试波长。第一滤波器的阻带光谱范围为λ 0±Δλ。第一滤波器将衰减业务光信号中波长范围在λ 0±Δλ内的光信号，衰减值为V2；业务光信号中波长范围在λ 0±Δλ外的光信号低损耗的通过第一滤波器，衰减值为V1。此处的V1可远远小于V2。如此，通过对λ 0±Δλ内的光信号大损耗的处理，相当于大部分滤除了业务信号中对测试波长的OTDR信号的测试干扰信号。而V1远远小于V2，可尽可能减低对于调制的业务数据的光信号的损耗，确保调制有业务数据的光信号的传输质量。
在本发明实施例中，所述WDM器可是一种无源器件，用于完成多个不同波长的光信号的复用和解复用。例如，棱镜色散型WDM器或衍射光纤型WDM器等。
在实际应用中，WDM器包括反射端、透射端及输出端。根据业务光信号的波长和OTDR信号的波长，从WDM器的反射端接收业务光信号，从透射端接收OTDR信号，从而通过WDM器衰减业务光信号中等于测试波长的干扰信号，同时衰减OTDR信号中测试波长范围外的干扰信号。
示例性地，如图3所示，图3是本发明实施例提供的OTDR内WDM器的衰减光谱图。对于通过WDM器反射端和输出端的光信号，WDM器将衰减光信号中波长范围在λ 0±Δλ内的光信号，衰减值为V8；光信号中波长范围在 λ 0±Δλ外的光信号低损耗的通过WDM器，衰减值为V7。而对于通过WDM器透射端和输出端的光信号，WDM器将衰减光信号中波长范围在λ 0±Δλ外的光信号，衰减值为V6；光信号中波长范围在λ 0±Δλ内的光信号低损耗的通过WDM器，衰减值为V5。此处的V7可远小于V8。如此，通过对业务光信号中波长范围在λ 0±Δλ内的光信号大损耗的处理，滤除业务光信号中对OTDR信号的测试造成干扰的信号。V5远远小于V6。如此，通过对λ 0±Δλ外的光信号进行高损耗处理，滤除OTDR信号中波长范围在λ 0±Δλ外的干扰信号。而V7远小于V8，V5远远小于V6，可尽可能降低对业务光信号和OTDR信号的损耗，确保OTDR的测试不对业务光信号的正常传输造成影响；同时，保证OTDR的测试也不受到业务光信号的影响。
在本发明实施例中，第一滤波器分别与OTDR的输入端和WDM器的反射端连接；WDM器的透射端与OTDR基本单元连接，WDM器的输出端与所述OTDR的输出端连接。
所述OTDR通过输入端接收输入的业务光信号，并通过第一滤波器对业务光信号进行滤波，过滤业务光信号中波长等于所述OTDR的测试波长的干扰信号，避免业务光信号对OTDR的测试造成影响。由OTDR基本单元发射等于测试波长的OTDR信号，并通过WDM器对过滤后的业务光信号和OTDR基本单元输出的OTDR信号合波，将合波信号传送至OTDR的输出端输出。同时，WDM器接收OTDR信号的返回信号，并发送至OTDR基本单元；OTDR基本单元根据接收的返回信号的返回参数，与OTDR信号的发射参数，评估OTDR输出端连接的光纤的性能指标。
示例性地，如图2、图3所示，当OTDR的测试波长为λ 0，光谱范围为λ 0±Δλ时，经过第一滤波器过滤后的业务光信号(波长范围在λ 0±Δλ外的光信号)通过反射端输入至WDM器；经过第一滤波器和WDM器后，业务光信号中波长范围在λ 0±Δλ内的光信号，衰减值为V2+V8；业务光信号中波长范围在λ 0±Δλ外的光信号低损耗的通过第一滤波器和WDM器，衰减值为V1+V7。
如此，通过在第一滤波器对业务光信号中波长等于所述OTDR的测试波长的干扰信号进行滤除，使得OTDR在不影响业务光信号的条件下，大幅度降低业务光信号中落在OTDR的测试波长范围内的干扰信号，确保OTDR的测试性能不受光纤线路中传输的业务光信号的影响。
在一些实施例中，所述设备还包括：
第二滤波器，与所述OTDR基本单元连接，用于过滤所述返回信号中的干 扰信号；其中，所述返回信号中的干扰信号的波长不等于所述测试波长。
在实际应用中，所述第二滤波器可以为带通滤波器，通带光谱范围可根据OTDR测试信号的波长进行设置；通过第二滤波器对返回信号中波长范围在通带光谱范围外的光信号进行大幅度衰减，而返回信号中波长范围在通带光谱范围内的光信号能低损耗通过第二滤波器。
示例性地，如图4所示，图4是本发明实施例提供的OTDR内第二滤波器的衰减光谱图。其中，OTDR的测试波长的中心波长为λ 0。第二滤波器的通带光谱范围为λ 0±Δλ。第二滤波器将衰减返回信号中波长范围在λ 0±Δλ外的光信号，衰减值为V4；返回信号中波长范围在λ 0±Δλ内的光信号低损耗的通过第二滤波器，衰减值为V3。此处的V4可远远小于V3。如此，通过对λ 0±Δλ外的光信号大损耗的处理，相当于对返回信号中波长范围在λ 0±Δλ外的信号进行尽可能大的衰减。而V4远远小于V3，可尽可能降低业务光信号的反向瑞利散射信号对返回信号的干扰，确保OTDR测试性能不劣化。
在本发明实施例中，所述第二滤波器与OTDR基本单元连接，用于滤除返回信号中的干扰信号。
OTDR通过输出端接收到OTDR信号的返回信号，WDM器通过输出端接收返回信号；并由透射端将返回信号传输至第二滤波器，第二滤波器对所述返回信号滤波后，将其传输至OTDR基本单元。
示例性地，如图3、图4所示，其中，OTDR的测试波长为λ 0。经过WDM器透射端输出的返回信号，通过第二滤波器滤除返回信号中的干扰信号(波长范围在λ 0±Δλ外的光信号)。经过WDM器和第二滤波器后，返回信号中波长范围在λ 0±Δλ外的光信号，衰减值为V6+V4；返回信号中波长范围在λ 0±Δλ内的光信号低损耗的通过WDM器和第二滤波器，衰减值为V5+V3。
如此，通过第二滤波器进一步滤除OTDR的返回信号中OTDR测试波长范围外的干扰信号。
在一些实施例中，所述OTDR基本单元包括：
发射模组，用于发射等于所述测试波长的OTDR信号；
接收模组，用于接收所述返回信号；
光环形器，分别与所述发射模组、所述接收模组及所述WDM器的所述透射端连接；
处理器，分别与发射模组、接收模组连接，用于根据所述OTDR信号的发射参数及所述返回信号的返回参数得到所述性能指标。
在本发明实施例中，发射模组是用于进行电光转换的光电子器件；例如，脉冲激光器等。所述发射模组包括光发射装置、及驱动电路；驱动电路接收到电信号后，根据接收的电信号驱动光发射装置发送设定波长的光信号。
在本发明实施例中，接收模组是用于进行光电转换的光电子器件。例如，雪崩二极管等。所述接收模组包括光接收装置、升压电路、微处理器(Microcontroller Unit，MCU)。其中，光接收装置用于将光信号转化为电信号，例如雪崩二极管等；升压电路用于为光接收装置提供偏置电压；MCU用于控制升压电路所输出的电压。
在本发明实施例中，光环形器是一种多端口的具有非互易特性的光器件。其至少包括三个端口，光环形器的端口间形成了一条连通的环形通道。当光信号从光环形器的任一端口输入时，都能按照端口环形通道的传输方向从下一端口以很小的损耗输出，而该端口通向其他端口的损耗都很大。该传输方向可为顺时针方向或者逆时针方向。
例如，环形器的传输方向为：从与发射模组连接的第一端口，到与WDM器连接的第二端口；再从第二端口到与接收模组连接的第三端口。
在本发明实施例中，处理器是信息处理、程序运行的执行单元，用于对接收的光信号进行处理分析，从而检测得到光纤的性能指标等参数。
在本发明实施例中，光环形器分别与发射模组、接收模组以及WDM器的透射端连接；处理器分别与发射模组、接收模组连接。
处理器驱动所述发射模组发射OTDR信号，所述OTDR信号通过光环形器传送至WDM器透射端，通过WDM器将OTDR信号和过滤后的业务光信号合波输出。WDM器将接收到的OTDR信号的返回信号通过光环形器传送至接收模组，接收模组接收到返回信号后，将返回信号的返回参数发送至处理器，以便处理器根据返回信号的返回参数和OTDR信号的发射参数，评估光纤的性能指标。
可选地，所述返回信号的返回参数包括：返回时间和返回功率；所述OTDR信号的发射参数包括：发射时间和发射功率。
在实际应用中，处理器记录所述返回信号的返回时间、返回功率，并根据所述OTDR信号的发射时间和发射功率，通过返回时间与发射时间之间的时间差，以及光在光纤中的传输速度，计算光纤的实际长度。根据返回功率和返回时间，绘制光纤的衰减分布曲线。
如此，通过OTDR基本单元发射OTDR信号，并接收OTDR信号的返回 信号，根据OTDR信号的发射参数和返回参数，评估光纤的性能指标，完成对光纤的测试。
可选地，所述光环形器包括：
第一端口、第二端口及第三端口；
所述第一端口与所述发射模组连接，所述第二端口与所述WDM器的所述透射端连接，所述第三端口与所述接收模组连接。
在本发明实施例中，光环形器分别与发射模组、WDM器以及接收模组连接；其中，第一端口与发射模组连接，第二端口与WDM器的透射端连接，第三端口与接收模组连接。
将发射模组发射的OTDR信号传送至WDM器的透射端，与业务光信号进行合波输出；并将WDM器发送的返回信号传送至接收模组，以根据返回信号的返回参数，评估光纤的性能指标。
例如，该性能指标包括但不限于以下至少之一：光纤的实际长度，光纤的衰减系数，光纤的损耗分布曲线，光纤的故障点位置。
在另一些实施例中，如图5所示，图5是本发明实施例提供的一种OTDR的一个可选的组成结构方框示意图。其中，所述第二滤波器串联在所述光环形器的第三端口和接收模组之间，用于滤除返回信号的干扰信号。
需要说明的是，业务光信号和OTDR信号同向传输时，业务光信号同样会在传输过程中产生瑞利散射信号，并返回传输至WDM器中。WDM器接收的返回信号中既包括OTDR信号的返回信号，也包括业务光信号的返回信号；业务光信号的返回信号会对OTDR的测试造成干扰。通过第二滤波器滤除返回信号中的业务光信号的返回信号，降低传输系统中业务光信号返回信号对OTDR信号的返回信号的干扰。
在实际实施时，光环形器将WDM器发送的返回信号传送至第二滤波器，第二滤波器滤除返回信号中的干扰信号；第二滤波器将过滤后的返回信号传送至接收模组，以根据返回信号的返回参数，评估光纤的性能指标。
如此，通过光环形器将发射模组发射的OTDR信号传输至WDM器的透射端；并将WDM器接收的OTDR信号的返回信号传输至接收模组，使得正向/反向传输的分离，实现单纤双向通信。
下面，本发明实施例提供一种基于OTDR的测试系统，如图6所示，图6是本发明实施例提供的一种基于OTDR的测试系统的结构示意图。所述系统包 括：
OTDR；
业务信号发射器，与所述OTDR的输入端连接，用于发射业务光信号；
待测光纤，与所述OTDR的输出端连接。
其中，所述OTDR为前述图1或图5中的OTDR。
在本发明实施例中，业务信号发射器与OTDR的输入端连接，OTDR的输出端与待测光纤连接。
OTDR通过输入端接收所述业务信号发射器发射的业务光信号，并通过第一滤波器对业务光信号进行滤波，滤除业务光信号中波长等于OTDR的测试波长的干扰信号。并且，OTDR的OTDR基本单元发射OTDR信号，并将其传输至WDM器；通过WDM器对过滤后的业务光信号和OTDR信号合波输出至OTDR的输出端，从而传输至与所述输出端连接的待测光纤中。通过所述输出端接收从所述待测光纤返回的OTDR信号的返回信号，并将返回信号经由WDM器传送至OTDR基本单元，从而根据所述返回信号的返回参数，评估待测光纤的性能指标。
可选地，如图7所示，图7是本发明实施例提供的一种基于OTDR的测试系统的一个可选的结构示意图。所述系统还包括：
监测设备，与所述OTDR连接，用于根据业务光信号的波长范围，确定所述OTDR的测试波长。
在本发明实施例中，监测设备与OTDR的处理器连接。通过监测设备设置OTDR的测试波长，并将测试波长信息发送给处理器，处理器驱动OTDR的发射模组发射所述测试波长对应的OTDR信号。其中，所述监控设备可根据业务光信号的波长范围，确定OTDR的测试波长。
需要说明的是，为了避免OTDR的测试对光纤传输的业务光信号的影响，应根据光纤传输的业务光信号的波长范围，确定OTDR的测试波长。例如，OTDR的测试波长应避开DWDM标准波长范围、OSC波长范围和拉曼泵浦波长范围等，这里就不具体限定了。
在实际实施时，为了达到更长的测试距离，测试波长还可以选择光纤衰减系数低的波长范围。例如，850nm、1550nm等，这里就不具体限定了。
如此，监测设备根据业务光信号波长，确定OTDR的测试波长，从而确保OTDR的测试性能不受光纤线路中传输的业务光信号的影响。
可选地，所述监测设备还用于：
接收并显示所述OTDR输出的所述待测光纤的性能指标。
在本发明实施例中，处理器接收到返回信号的返回参数后，根据返回信号的返回参数和OTDR信号的发射参数，评估待测光纤的性能指标；并将所述待测光纤的性能指标参数发送至监测设备以进行显示。
其中，所述返回信号的返回参数包括：返回时间和返回功率；所述OTDR信号的发射参数包括：发射时间和发射功率。
实际实施时，处理器通过返回时间与发射时间之间的时间差，以及光在光纤中的传输速度，计算待测光纤的实际长度。根据返回功率和返回时间，绘制光纤的衰减分布曲线。并将待测光纤的实际长度、衰减分布曲线发送至监测设备以进行显示。
如此，通过返回信号的返回参数和OTDR信号的发射参数，评估待测光纤的性能指标，并由监测设备更为直观对待测光纤的性能指标进行显示，从而便于光纤传输线路的维护。
下面，本发明实施例提供一种基于OTDR的测试方法，如图8所示，图8是本发明实施例提供的一种基于OTDR的测试方法的流程示意图。所述方法包括：
步骤801：根据业务光信号的波长，确定OTDR的测试波长；
步骤802：根据所述测试波长，向待测光纤发射OTDR信号；
步骤803：滤除所述业务光信号中等于所述测试波长的干扰信号；
步骤804：接收所述待测光纤返回的OTDR信号的返回信号；其中，所述OTDR信号的发射参数及所述返回信号的返回参数，用于评估连接在所述WDM器连接的输出端的光纤的性能指标。
在本发明实施例中，OTDR包括输入端、第一滤波器、WDM器、OTDR基本单元、输出端。其中，输入端与第一滤波器连接，第一滤波器又与WDM器的反射端连接，WDM器的透射端与OTDR基本单元连接，WDM器的输出端与OTDR的输出端连接。
在本实施例的步骤801中，根据业务光信号的波长，确定OTDR的测试波长，以确保OTDR的测试性能不受光纤线路中传输的业务光信号的影响。
在实际实施时，在确定OTDR的测试波长时，应综合考虑业务光信号的波长以及光纤衰减系数，选择光纤衰减系数低的波长，以达到更长的测试距离。例如，850nm、1550nm等，这里就不具体限定了。
需要说明的是，为了避免OTDR的测试对业务光信号的影响，在选择OTDR的测试波长时，应尽量避开与业务光信号的波长一致。例如，OTDR的测试波长应避开DWDM标准波长范围、OSC波长范围和拉曼泵浦波长范围等，这里就不具体限定了。
在本实施例的步骤802中，OTDR的处理器根据测试波长，驱动所述OTDR基本单元的发射模组发射测试波长对应的OTDR信号，OTDR信号通过光环形器传输至WDM器，并由WDM器向连接在OTDR输出端的待测光纤发送OTDR信号。
在本实施例的步骤803中，通过OTDR的输入端接收业务光信号，并通过第一滤波器滤除业务光信号中等于所述测试波长的干扰信号；将滤波后的业务光信号传输至WDM器，由WDM器向连接在OTDR输出端的待测光纤发送业务光信号。
需要说明的是，光传输系统中各种放大器的应用导致光纤线路中的噪声信号(例如ASE信号)广泛存在，并且光谱分布较广；噪声信号对OTDR的测试性能产生严重干扰。在WDM器对业务光信号和OTDR信号合波之前，通过第一滤波器对业务光信号中波长等于测试波长的噪声信号进行滤波，降低光纤线路中业务光信号对OTDR的测试影响。
如此，通过第一滤波器对业务光信号中波长等于所述OTDR的测试波长的干扰信号进行滤除，使得OTDR在不影响业务光信号的条件下，大幅度降低业务光信号中落在OTDR的测试波长范围内的干扰信号，确保OTDR的测试性能不受光纤线路中传输的业务光信号的影响。
在一些实施例中，所述步骤801可包括：当所述业务光信号为经过掺饵光纤放大器EDFA放大的光信号时，根据所述业务光信号的波长范围和EDFA的自发辐射ASE信号的光谱分布，确定OTDR的测试波长。
在本发明实施例中，EDFA包括掺饵光纤、泵浦光源、耦合器、光隔离器及光滤波器；EDFA在对业务光信号进行功率放大时，也会产生放大器ASE噪声。根据业务光信号的波长范围和EFDA的ASE信号的光谱分布，确定OTDR的测试波长。
需要说明的是，在光纤放大器中，随着激活例子从激发态返回基态并放大光信号的同时，也会产生受激粒子的随机非相干自发辐射；这种自发辐射可在任何方向，并可引起进一步受激辐射，且可被放大。因此，ASE的频带很宽，可占据整个增益带宽。
在实际实施时，根据EDFA的ASE信号的光谱分布，确定ASE信号功率较低的波长范围，以避免EDFA放大器的ASE信号对OTDR的测试的影响。
示例性地，如图9所示，图9是EDFA产生的ASE信号的光谱分布图，其中，图9中包含了四个不同增益下的ASE信号光谱分布曲线。EDFA的ASE的功率在低于1528nm波长范围和高于1563nm波长范围开始明显下降。因此，根据ASE信号的光谱分布，可在图9中ASE功率较低的波长范围中选择OTDR的测试波长。例如，测试波长为低于1520nm，或高于1600nm等。
如此，在OTDR信号和EDFA输出信号同向传输系统中，通过对EDFA产生的ASE信号中波长等于测试波长的干扰信号进行滤除，降低光纤传输线路中业务光信号对OTDR信号的影响，保证OTDR的测试性能不劣化。
在一些实施例中，步骤804包括：
接收所述OTDR信号的返回信号，记录所述返回信号的返回参数，所述返回参数包括返回时间和返回功率；
获取所述处理器预先记录的所述OTDR信号的发射参数，所述发射参数包括发射时间、发射功率；
根据所述OTDR信号的发射时间和所述返回信号的返回时间，确定所述待测光纤的长度；
根据所述OTDR信号的发射参数和所述返回信号的返回参数，确定所述待测光纤的衰减分布曲线。
在实际应用中，通过记录返回信号的返回时间和返回功率；并根据OTDR信号的发射时间和发射功率；根据返回时间与发射时间之间的时间差，以及光在光纤中的传输速度，计算待测光纤的长度；并且，根据返回功率和返回时间，绘制光纤的衰减分布曲线。
如此，通过返回信号的返回参数和OTDR信号的发射参数，评估待测光纤的性能指标，从而保证光纤传输线路的质量。
本发明实施例还提供一种计算机存储介质，所述计算机存储介质存储有计算机程序，所述计算机程序被处理器执行后，并执行前述一个或多个技术方案提供的数据传输方法，例如，可执行如图8所示的方法。
本发明实施例提供的计算机存储介质包括：移动存储设备、只读存储器(ROM，Read-Only Memory)、随机存取存储器(RAM，Random Access Memory)、磁碟或者光盘等各种可以存储程序代码的介质。可选为，所述计算机存储介质 可为非瞬间存储介质。这里的非瞬间存储介质又可以称为非易失性存储介质。
以下结合上述任意一个技术方案提供一个具体示例：
本示例提供一种基于OTDR的测试系统，所述测试系统包括：
OTDR；
待测光纤；
业务信号发射器。
其中，所述OTDR包括输入端、第一滤波器、WDM器、第二滤波器及OTDR基本单元。如图10所示，图10是本发明实施例提供的OTDR内光信号的流向示意图。通过第一滤波器对从输入端接收的业务光信号进行滤波；通过WDM器将滤波后的业务光信号与OTDR基本单元发射的OTDR信号进行合波，并输出至WDM器连接的输出端的光纤中。通过WDM器接收OTDR信号的返回信号，并通过第二滤波器滤除返回信号中的干扰信号，将过滤后的返回信号传送至OTDR基本单元，以评估所述光纤的性能指标。
在本示例中，选择1519nm作为OTDR信号的测试波长，将OTDR信号的光谱宽度设置为1519nm±1nm，OTDR的OTDR基本单元的发射模组的输出光脉冲峰值功率为17dBm，脉冲宽度为20us。EDFA增益为33dB，EDFA信号与OTDR输出信号同向传输。
假设传输光纤线路长为125km，1519nm的光纤损耗系数约为0.2dB/km；第一滤波器采用单级镀膜滤波器，第二滤波器采用双级镀膜滤波器。
根据常规滤波器及WDM器的衰减特性，假设V1＝0.8dB，V2＝35dB，V3＝1.6dB，V4＝70dB，V5＝0.8dB，V6＝35dB，V7＝0.5dB，V8＝15dB。
根据图X的EDFA产生的ASE信号的光谱分布可见，在波长为1519nm时，ASE信号的功率大约为-32.5dBm；而连续光信号在传输光纤中瑞利散射后向信号积分典型值为-32dB。因此，在波长范围为1519nm±1nm内，EDFA的ASE噪声信号经过传输光纤后，其后向积分功率在OTDR的输出端的功率为：
Pase_r＝-32.5-35-15-32＝-114.5dBm
这里，Pase_r是指在波长范围为1519nm±1nm内，OTDR输出端处的ASE信号的后向瑞利散射功率的积分值。
若从OTDR的输入端接收的业务光信号，不经过第一滤波器滤波，直接从WDM的反射端输入，然后从OTDR的输出端输出；在波长范围为1519nm±1nm内，EDFA的ASE噪声信号经过传输光纤后，其后向积分功率在OTDR的输出 端的功率为：
Pase_r＝-32.5-15-32＝-79.5dBm
脉冲信号在单模光纤中的瑞利散射系数如下：
K(Δt)＝10log 10(KΔt)
Figure PCTCN2021100624-appb-000001
其中，S是后向散射俘获因子，与光纤类型的数值孔径相关；
Figure PCTCN2021100624-appb-000002
对单模光纤，m＝4.55，NA是光纤的数字孔径，n 0是光纤的折射率；α s是光纤的散射系数；ν是光在光纤中的传播速度，
Figure PCTCN2021100624-appb-000003
C是光在真空中的传输速度，n 0是光纤的折射率；Δt是光脉冲的宽度。
在常用的单模光纤中，例如G.652D，NA＝0.14，通过计算得到：K＝10s -1，对其取对数并转换为ns，得到脉冲宽度为1ns时，后向散射系数为：
Figure PCTCN2021100624-appb-000004
这里，K ns(dB)指的是脉冲宽度为1ns的光脉冲信号，在光纤线路上每一点的后向散射系数。
当脉冲宽度为Δtns时，后向散射系数为：
K(Δt)＝10log 10(KΔt)＝K ns(dB)+10log 10(KΔt)≈-80+10log 10(KΔt)
这里，K(Δt)指的是脉冲宽度为Δtns的光脉冲信号，在光纤线路上每一点的后向散射系数。
OTDR的输出脉冲峰值功率为17dBm，脉冲宽度为20us时，计算所得后向散射系数为-37dB；脉冲宽度为1us时，计算所得后向散射系数为-50dB。
波长为1519nm的光信号在光纤中的衰减系数大约为0.2dB/km，125km出的OTDR光脉冲信号的瑞利散射光信号返回到OTDR的输出端的光功率为：
脉冲宽度为20us时：17-0.8-0.8-0.2×125×2-37＝-71.6dBm
脉冲宽度为1us时：17-0.8-0.8-0.2×125×2-50＝-84.6dBm
由此可见，若OTDR中没有第一滤波器，ASE信号后向积分功率为-79.5dBm，比125km处光纤返回的脉冲宽度为20us的OTDR信号的返回信号功率-71.6dBm仅低7.9dB，比脉冲宽度为1us的返回信号还高5.01dB。而对于包括第一滤波器的OTDR，ASE信号后向积分功率为-114.5dBm，远小于125km处光纤返回的脉冲宽度为20us的OTDR信号的返回信号功率-71.6dBm和脉冲宽 度为1us的返回信号功率-84.6dBm。
第二滤波器的作用是为了滤波返回信号中测试波长范围外的噪声信号，在同向传输系统中，广大光谱范围内的业务光信号与OTDR的OTDR信号同向传输，业务光信号同样在传输过程中产生瑞利散射。
假设同向传输的业务光信号的总功率为24dBm，根据连续光信号在传输光纤中瑞利散射后向信号积分典型值为-32dB，在OTDR的输出端，业务光信号的反向瑞利散射的功率值为：
24-0.8-9.8-32＝-9.6dBm
瑞利散射返回的业务光信号，经过WDM器和第二滤波器后，传输至OTDR基本单元的接收模组处，波长范围为1519nm±1nm的业务光信号的光功率为：
-9.6-35-70＝-114.6dBm
若OTDR中没有第二滤波器，返回信号传输至OTDR基本单元的接收模组处，波长范围为1519nm±1nm的业务光信号的光功率为：
-9.6-35＝-44.6dBm
由此可知，在OTDR基本单元的接收模组处OTDR信号的返回的瑞利散射信号为：
脉冲宽度为20us时：-71.6-0.8-1.6＝-74dBm
脉冲宽度为1us时：-84.6-0.8-1.6＝-87dBm
由此可知，第二滤波器对业务光信号的反向瑞利光信号起到关键滤波作用。若OTDR中没有第二滤波器，业务光信号的反向瑞利散射信号功率达到-44.6dBm，远大于OTDR信号的返回信号功率-74dBm。而对于包括第二滤波器的OTDR，业务光信号的反向瑞利散射信号功率为-114.6dBm，远小于OTDR信号的返回信号功率。
本实施例中，OTDR中第一滤波器滤除同向传输信号中波长等于测试波长的干扰信号，第二滤波器滤除同向传输信号的反向瑞利散射信号，大幅度降低传输系统中业务光信号对OTDR的OTDR信号的干扰，极大限度地降低了在线OTDR测试系统的性能劣化。
在本申请所提供的几个实施例中，应该理解到，所揭露的设备和方法，可以通过其它的方式实现。以上所描述的设备实施例仅仅是示意性的，例如，所述单元的划分，仅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，如：多个单元或组件可以结合，或可以集成到另一个系统，或一些特征可以忽略，或不执行。另外，所显示或讨论的各组成部分相互之间的耦合、或直接耦 合、或通信连接可以是通过一些接口，设备或单元的间接耦合或通信连接，可以是电性的、机械的或其它形式的。
上述作为分离部件说明的单元可以是、或也可以不是物理上分开的，作为单元显示的部件可以是、或也可以不是物理单元，即可以位于一个地方，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全部单元来实现本实施例方案的目的。
另外，在本发明各实施例中的各功能单元可以全部集成在一个处理模块中，也可以是各单元分别单独作为一个单元，也可以两个或两个以上单元集成在一个单元中；上述集成的单元既可以采用硬件的形式实现，也可以采用硬件加软件功能单元的形式实现。
本领域普通技术人员可以理解：实现上述方法实施例的全部或部分步骤可以通过程序指令相关的硬件来完成，前述的程序可以存储于一计算机可读取存储介质中，该程序在执行时，执行包括上述方法实施例的步骤；而前述的存储介质包括：移动存储设备、只读存储器(ROM，Read-Only Memory)、随机存取存储器(RAM，Random Access Memory)、磁碟或者光盘等各种可以存储程序代码的介质。
以上所述，仅为本发明的实施例而已，并非用于限定本发明的保护范围。凡在本发明的精神和范围之内所作的任何修改、等同替换和改进等，均包含在本发明的保护范围之内。

Claims (11)

  1. 一种光纤时域反射仪OTDR，其特征在于，包括：
    输入端，用于接收输入的业务光信号；
    第一滤波器，与所述输入端相连，用于过滤所述业务光信号中波长等于所述OTDR的测试波长的干扰信号；
    波分复用WDM器，具有反射端、透射端及输出端，其中，所述反射端与所述第一滤波器连接，用于接收所述第一滤波器过滤后的所述业务光信号；
    OTDR基本单元，与所述透射端连接，用于发射等于所述测试波长的OTDR信号，并接收所述OTDR信号的返回信号，其中，所述OTDR信号的发射参数及所述返回信号的返回参数，用于评估连接在所述WDM器连接的输出端的光纤的性能指标；
    所述WDM器的输出端，用于输出从所述反射端接收的过滤后的业务光信号，并输出从所述透射端接收的所述OTDR信号，并接收从所述光纤返回的所述返回信号。
  2. 根据权利要求1所述的光纤时域反射仪，其特征在于，所述设备还包括：
    第二滤波器，与所述OTDR基本单元连接，用于过滤所述返回信号中的干扰信号；其中，所述返回信号中的干扰信号的波长不等于所述测试波长。
  3. 根据权利要求1所述的光纤时域反射仪，其特征在于，所述OTDR基本单元包括：
    发射模组，用于发射等于所述测试波长的OTDR信号；
    接收模组，用于接收所述返回信号；
    光环形器，分别与所述发射模组、所述接收模组及所述WDM器的所述透射端连接；
    处理器，分别与发射模组、接收模组连接，用于根据所述OTDR信号的发射参数及所述返回信号的返回参数得到所述性能指标。
  4. 根据权利要求3所述的光纤时域反射仪，其特征在于，所述光环形器包括：
    第一端口、第二端口及第三端口；
    所述第一端口与所述发射模组连接，所述第二端口与所述WDM器的所述透射端连接，所述第三端口与所述接收模组连接。
  5. 一种基于光纤时域反射仪OTDR的测试系统，其特征在于，所述系统包括：
    如权利要求1-4任一项所述的OTDR；
    业务信号发射器，与所述OTDR的输入端连接，用于发射业务光信号；
    待测光纤，与所述OTDR的输出端连接。
  6. 根据权利要求5所述的测试系统，其特征在于，所述系统还包括：
    监测设备，与所述OTDR连接，用于根据业务光信号的波长范围，确定所述OTDR的测试波长。
  7. 根据权利要求5所述的测试系统，其特征在于，所述监测设备还用于：
    接收并显示所述OTDR输出的所述待测光纤的性能指标。
  8. 一种基于光纤时域反射仪OTDR的测试方法，其特征在于，所述方法包括：
    根据业务光信号的波长，确定OTDR的测试波长；
    根据所述测试波长，向待测光纤发射OTDR信号；
    滤除所述业务光信号中等于所述测试波长的干扰信号；
    接收所述待测光纤返回的OTDR信号的返回信号；其中，所述OTDR信号的发射参数及所述返回信号的返回参数，用于评估连接在所述WDM器连接的输出端的光纤的性能指标。
  9. 根据权利要求8所述的方法，其特征在于，所述根据业务光信号的波长范围，确定OTDR的测试波长，包括：
    当所述业务光信号为经过掺饵光纤放大器EDFA放大的光信号时，根据所述业务光信号的波长范围和EDFA的自发辐射ASE信号的光谱分布，确定OTDR的测试波长。
  10. 根据权利要求8所述的方法，其特征在于，所述接收并分析所述待测 光纤返回的OTDR信号的返回信号，包括：
    接收所述OTDR信号的返回信号，记录所述返回信号的返回参数；所述返回参数包括返回时间和返回功率；
    获取所述处理器预先记录的所述OTDR信号的发射参数；所述发射参数包括发射时间和发射功率；
    根据所述OTDR信号的发射时间和所述返回信号的返回时间，确定所述待测光纤的长度；
    根据所述OTDR信号的发射参数和所述返回信号的返回参数，确定所述待测光纤的衰减分布曲线。
  11. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质存储有计算机可执行指令；所述计算机可执行指令被处理器执行后，能够实现如权利要求8至10任一项所述的测试方法。
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