WO2012146078A1

WO2012146078A1 - Method and device for detecting optical time-domain detection signals

Info

Publication number: WO2012146078A1
Application number: PCT/CN2012/071469
Authority: WO
Inventors: 胡颖新; 王光军; 陈冀兵
Original assignee: 华为海洋网络有限公司
Priority date: 2011-04-29
Filing date: 2012-02-22
Publication date: 2012-11-01
Also published as: CN102761364A

Abstract

Provided are a device for detecting optical time-domain detection signals (OTDR) and a method for detecting related coherent optical time-domain detection signals. The method includes: dividing the successive coherent optical signals emitted by a coherent light source into two bundles, with a first bundle being used as detection light and a second bundle as local oscillator light; modulating the detection light according to a related code pattern sequence to generate a pulse sequence optical signal, and inputting the same into an optical fibre to be tested; receiving back-scattering light from the optical fibre to be tested, performing coherence processing on the back-scattering light and the local oscillator light, and converting the optical signal obtained by coherence processing to a digital signal; and performing data related processing on the digital signal and the related code pattern sequence to obtain and output an optical time-domain detection signal. The solution in the present invention combines the advantages of related and coherent OTDRs, making good the inadequacies thereof, and realizing high-resolution OTDR detection with high dynamic range.

Description

Method and device for detecting optical time domain detection signal

This application claims priority to Chinese Patent Application No. 201110111702.3, entitled "A Method and Apparatus for Detecting Optical Time Domain Detection Signals", filed on April 29, 2011, the entire contents of which are incorporated by reference. Combined in this application.

Technical field

The present invention relates to the field of optical communication technologies, and in particular, to a method and apparatus for detecting an optical time domain detection signal.

Background technique

Optical Time-Domain Reflectometry (OTDR) is based on the principle of backscattering and reflection of light. The backscattered light generated by the propagation of light in an optical fiber is used to obtain attenuation information, which can be used to measure optical fibers. Attenuation, joint loss, fiber fault location, and loss distribution along the length of the fiber. Due to the uneven density of the fiber material, the uneven doping composition, and the defect of the fiber itself, when light is transmitted in the fiber, scattering occurs at every point along the length of the fiber. The optical time domain reflectometer records the intensity of the scattered light collected at each time point. Since the speed of light is fixed, the time of collecting the signal has a corresponding relationship with the distance of light travel in the fiber, so the time can be converted into the length of the fiber. Figure 1 shows a typical representation of the OTDR detection signal curve. The abscissa indicates the length of the fiber (in km) and the ordinate indicates the relative intensity of the scattered light signal (in dB). It can be seen that the curve 100 gradually decreases with the increase of the length of the fiber, but the trend is very gentle, and 104 indicates the change of the intensity of the OTDR detection signal between the two points due to the difference in the length of the fiber. The curve 100 exhibits a significant change at the splice 101, the connection 102, the break, or the end of fiber 103, indicating that light will reflect or scatter in these places. Part of the scattered and reflected light can be transmitted back to the optical time domain reflectometer. . The significant change regions (105, 106, 107) in the graph of Fig. 1 are referred to as reflection events and decay events. From the change in the intensity of the received light, the transmission characteristics of the various positions of the optical fiber can be judged.

The traditional OTDR measurement principle: a pulsed optical signal with a controllable width is coupled into the optical fiber. The process of transmitting the pulsed light in the optical fiber is accompanied by the occurrence of scattering, and the partially scattered signal opposite to the direction of the pulse transmission finally returns to the OTDR. The OTDR receives the signal through the coupler and converts it into a digital signal by analog-to-digital conversion. The digital signal is converted into a curve with the length of the fiber (in km) as the abscissa and the relative intensity (in dB) as the ordinate. The curve is a straight line that gradually decays as the length of the fiber increases from the beginning of the fiber. However, due to the existence of fusion and fracture in the fiber, production at these locations Additional losses and reflections are produced, which are represented by reflection events and attenuation events in Figure 1. The OTDR measurement relies on this curve 100 with reflection and attenuation events to analyze the state of the fiber link. If some positions are too strong and the loss is too large, there is an abnormality, and the horizontal axis of the curve is the length of the fiber, so the position of these reflection and attenuation events can be derived.

The OTDR measures the scattered signal of light. The light scattering signal is related to the peak power and pulse width of the probe pulse light, and decreases as the transmission distance increases. The intensity of the scattered signal of this light is weak and easily annihilated in the noise, which limits the OTDR detection distance, which corresponds to the "dynamic range" of the indicator. The "dynamic range" is used to characterize the maximum distance detected by the OTDR. A common definition of "dynamic range" is to take the dB difference between the initial backscatter level and the noise peak level. Common ways to improve the dynamic range are: increasing the average number of times, increasing the width of the probe pulse, and using digital filtering techniques.

In order to get a better signal-to-noise ratio (that is, to increase the dynamic range and extend the detectable distance), multiple accumulation techniques (also called averaging) are usually used. The implementation of the multiple accumulation technique is as follows: OTDR control The laser sends a pulse signal into the fiber. The pulse signal continuously generates backscattered signals during fiber transmission and returns to the OTDR with the coupler. The OTDR continuously receives the backscattered signal from the moment the pulse is transmitted. The OTDR performs photoelectric conversion, signal amplification, analog-to-digital conversion, and storage on the received backscattered signal. This process generally continues until the detected scatter signal at the end of the fiber returns to the OTDR meter. That is, the detection pulse is twice as long as the transmission time in the entire fiber (the backscatter signal also has a return transmission process, which is twice the time for forward transmission). This process is called an OTDR. By repeating this process, the data obtained from multiple samples is cumulatively averaged to suppress white noise and improve the signal-to-noise ratio of the OTDR signal. Figure 2a shows the OTDR measurement results when the average number of times is small, and Figure 2b shows the OTDR measurement results when the average number of times is large. The abscissa of the two figures represents the length of the fiber (in km) and the ordinate is the relative intensity of the data (in dB). It can be seen from the comparison of Fig. 2a and Fig. 2b that the sharply changing regions in Figs. 2a and 2b appear at substantially the same position, but the sharply varying regions in Fig. 2b are more distinct from the other portions, indicating that the dynamic range is on average. Increased after the number of times increased.

Figure 3 is a block diagram showing the structure of the OTDR principle. The pulse generator 303 emits a narrow pulse drive laser 301 of adjustable width, and the laser 301 produces pulsed light of a desired width. The graph above the arrow from laser 301 to coupler 302 in Figure 3 is a schematic representation of the waveform of the pulsed light. The pulsed light is directional coupled by the coupler 302 and then incident on the fiber 308 under test, the backscattered light and the Fresnel reflected light in the optical fiber 308. The coupler 302 enters the photodetector 305, and the photodetector 305 converts the received scattered light and reflected light signals into electrical signals, which are amplified by the amplifier 306 and sent to the signal processing unit 307 for processing (including the sample unit, the analog to digital conversion unit, and The averaging unit), the processed result is displayed by the display unit 309: the vertical axis represents the power level, and the horizontal axis represents the distance. The time base and control unit 304 controls the pulse generator 303 to emit a width of a narrow pulse of adjustable width, and controls the sampling of the sample unit in the signal processing component 307 and the average of the average cells.

The submarine cable monitoring equipment is a kind of equipment for daily maintenance and fault location of the submarine cable. It also uses OTDR technology. The submarine cable monitoring device transmits the probe light to the submarine cable, and detects the working state of the underwater equipment such as the underwater submarine cable and the repeater by using the back Rayleigh scattering signal of the received probe light. In different scenarios, the submarine cable system has a specific range of limits for the detection optical power and signal pulse width; in order to obtain effective monitoring accuracy, the signal pulse width must also be limited to a certain range. Therefore, how to obtain a larger dynamic range and higher monitoring accuracy under the condition that the detection signal power and pulse width are limited is a problem that the submarine cable monitoring equipment needs to solve.

Since the submarine cable system is a cascade system with multiple repeaters, it has both fiber optic transmission and relay amplification systems in both the upstream and downstream directions. Each repeater of the submarine cable system has a loopback function that ensures that the backscattered signal generated by the probe pulse can be coupled to the reverse transmission line and sent back to the submarine cable monitoring device. The OTDR signal representation of the submarine cable system is shown in Figure 4. The abscissa is the length of the submarine cable and the ordinate is the relative strength of the OTDR signal. Each of these peak positions corresponds to a repeater and amplifier. The maximum detection distance of the OTDR signal is 600km, so the signal with a distance of 600km is noise.

The OTDR described above uses single pulse detection light for detection. If the OTDR spreads the single-pulse probe light into pulse sequence probe light and further utilizes the correlation between the pulse sequences, it is called the associated OTDR (Co-relation OTDR). The related OTDR detects the light by transmitting a pulse sequence and performs correlation calculation on the received scattered signal. This correlation processing can effectively improve the signal-to-noise improvement signal-to-noise ratio of the received signal, effectively solve the contradiction between the resolution and the dynamic range of the optical fiber event, and improve the detection. performance.

FIG. 5 is a block diagram showing the principle structure of the related OTDR in the prior art, in which solid arrows between modules indicate optical signals, and dotted arrows between modules indicate electrical signals. The pattern generator 505 is configured to generate a pulse sequence (the pattern above the arrow of the pattern generator 505 to the associated processing unit 507 is its waveform diagram), the pulse sequence is sent to the modulator 502, and the laser light emitted by the laser 501 is modulated into The pulse train detects light (the pattern above the arrow from modulator 502 to coupler 503 is its waveform diagram), and the pulse train probe light is directional coupled by coupler 503 and incident on fiber 504. The reflected light and the scattered light signal collected by the coupler 503 are converted into electrical signals by the photodetecting unit 506, processed by the correlation processing unit 507, and output to the display device (not shown in FIG. 5) to display the analysis result ( The graph above the arrow on the right of the correlation processing unit 507 is its waveform diagram).

The biggest difference between the related OTDR and the traditional OTDR measurement principle described above is that this technique does not send a pulse, but a pulse sequence, in the "every sample process". This pulse sequence is designed for correlation calculation. The most popular correlation code at present is Gray code, which consists of four groups of codes, which are digitally represented as a string of 0s and 1s. . The signal sent by the laser is continuous light. Under the control of the pattern generator, the modulator modulates the continuous light into a group of Gray code sequences. The set of Gray codes enters the fiber transmission through the coupler, and the receiving sample process continues until This set of codes is completely transmitted out of the end of the fiber, and its backscattered signal has completely returned to the OTDR meter, thus completing the "one sample process" of "a set of Gray code". Usually, four sets of Gray codes are sequentially processed through this process, and finally four sets of sample data are obtained. The four sets of sample data and the digital Gray code generated by the pattern generator are respectively related to calculation and data recombination, and can still be restored to the backscatter signal form obtained by the conventional OTDR transmitting single pulse, and the difference is that the digital correlation processing has noise suppression. To improve the signal-to-noise ratio, the OTDR signal has been improved.

The related OTDR method is a digital processing method. The data processing capability of the system is extremely high. In order to obtain a larger dynamic range, the operation complexity is proportional to the square of the number of pulse sequences in the case where the amount of data is constant. Moreover, when the signal-to-noise ratio is lower than a certain level, the correlation effect is drastically deteriorated, and the effect of increasing the dynamic range is lost.

Coherent OTDR (Coherent OTDR) utilizes the coherence characteristics of light to improve detection performance. When the submarine cable monitoring device sends a probe pulse to the submarine cable, a part of the detected light is separated as a local oscillator and the received backscattered signal is coherent, thereby Improve the signal-to-noise ratio of the received signal, thereby improving the monitoring performance of the submarine cable monitoring equipment.

FIG. 6 is a block diagram showing the structure of the coherent OTDR in the prior art. The coherent light from the coherent light source 601 is split into two paths in the first coupler 602, and the first path becomes a single pulse signal through the modulator 603 (the pattern above the arrow from the modulator 603 to the coupler 604 is a waveform diagram of the single pulse signal) And sent to the optical fiber 606 under test via the second coupler 604. The second path is transmitted as a local oscillator (continuous light) to the coherent receiver 605 (the pattern on the left side of the arrow from the coupler 602 to the coherent receiver 605 is a local oscillator) Waveform diagram). The second coupler 604 receives the reflected scattered light from the fiber 606 under test and is also transmitted to the coherent receiver 605 via the second coupler 604. The coherent receiver 605 uses heterodyne coherent technology to coherently receive the backscattered signal and the local oscillator, and finally obtains the OTDR signal in the form of Figure 1. The signal-to-noise ratio of the coherent OTDR signal is significantly improved compared with the ordinary OTDR. . This coherent OTDR technology uses a single-pulse signal for detection, which is an important difference from the related OTDR technology.

Coherent detection technology currently uses only a number of auxiliary methods such as multiple accumulation and digital filtering to improve the dynamic range, and has limited ability to improve the dynamic range at the digital signal processing level.

Summary of the invention

The invention provides a method and a device for detecting an optical time domain detection signal, which integrates correlation and coherence

The advantages of OTDR make up for the shortcomings of both, achieving high dynamic range and high resolution OTDR detection.

Embodiments of the present invention provide an apparatus for detecting an optical time domain detection signal, the detection apparatus including a coherent light source (701), a first coupler (702), a modulator (703), a second coupler (704), and a coherent reception. Machine (706), pattern generator (707) and associated processing unit (708);

The coherent light source (701) is configured to emit a continuous coherent light signal;

The first coupler (702) is configured to split the continuous coherent optical signal emitted by the coherent light source (701) into two output, the first beam entering the modulator (703) as the probe light, and the second beam as the local oscillator Entering the coherent receiver (706);

The pattern generator (707) is configured to generate a correlation pattern sequence, and the correlation pattern sequence is output to a modulator (703) and an associated processing unit (708), respectively;

The modulator (703) is configured to modulate the input probe light according to the associated pattern sequence from the pattern generator (707), generate a pulse sequence optical signal, and output the pulse sequence optical signal to the second Coupler (704);

The second coupler (704) is configured to directionalally couple the pulse sequence optical signal from the modulator (703) to the fiber under test; and to receive backscattered light from the fiber under test, and Backscattered light output to a coherent receiver (706);

The coherent receiver (706) is configured to coherently process the local oscillator light from the first coupler (702) and the backscattered light from the second coupler, and convert the optical signal obtained by the coherent processing into a digital signal. Input the relevant processing unit (708); The correlation processing unit (708) is configured to digitally correlate the digital signal from the coherent receiver (706) with the associated pattern sequence from the pattern generator (707) to obtain and output an optical time domain detection signal. The embodiment of the invention further provides a method for detecting an optical time domain detection signal, comprising the steps of: dividing a continuous coherent optical signal emitted by a coherent light source into two beams, a first beam as the probe light and a second beam as the local oscillator light;

Modulating the probe light according to a correlation pattern sequence, generating a pulse sequence optical signal, and inputting the pulse sequence optical signal into the optical fiber to be tested;

Receiving backscattered light from the fiber under test, coherently processing the backscattered light and the local oscillator light, and converting the optical signal obtained by the coherent processing into a digital signal;

The digital signal is digitally correlated with the associated pattern sequence to obtain and output an optical time domain detection signal.

It can be seen from the above technical solution that the present invention uses the coherent OTDR technology to improve the signal-to-noise ratio of the backscattered signal at the optical level, and can maintain the correlation characteristics of the signal, and then use the digital correlation operation to process the signal, which can effectively improve the dynamics. range. This combines the advantages of related and coherent OTDRs to compensate for the shortcomings of both, enabling high dynamic range and high resolution OTDR detection.

DRAWINGS

Figure 1 is a schematic diagram showing a typical representation of a signal curve of an optical time domain reflectometer;

Figure 2a is a schematic diagram of OTDR measurement results when the average number of times is small; Figure 2b is a schematic diagram of OTDR measurement results when the average number of times is large;

3 is a block diagram showing the structure of an OTDR in the prior art;

Figure 4 is a schematic diagram of the OTDR signal representation of the submarine cable system;

5 is a schematic structural block diagram of a related OTDR in the prior art;

6 is a block diagram showing the principle structure of a coherent optical OTDR in the prior art; FIG. 7a is a block diagram of a detecting apparatus for a correlated coherent optical time domain detecting signal according to Embodiment 1 of the present invention;

FIG. 7b is a block diagram of a device for detecting a correlated coherent optical time domain detection signal according to Embodiment 2 of the present invention; Figure

8 is a block diagram of a related coherent OTDR detecting apparatus according to Embodiment 3 of the present invention; FIG. 9 is a flow chart of a method for detecting a correlated coherent optical time domain detecting signal according to Embodiment 4 of the present invention.

detailed description

FIG. 7a is a block diagram of an apparatus for detecting a correlated coherent optical time domain detection signal according to Embodiment 1 of the present invention. The key signal flow shown in Figure 7a is annotated as follows:

1 detecting a pulse sequence optical signal;

2 local vibration;

3 detecting a backscattered light signal generated by the pulse sequence light transmitted in the optical fiber;

4 digital signal after coherent reception of the local oscillator and the backscattered optical signal;

5 detecting the digital form of the pulse sequence;

6 OTDR signal after correlation operation.

The continuous coherent optical signal from the coherent light source 701 is split into two beams by a first coupler 702, one beam entering the modulator 703 as probe light and the other beam entering the coherent receiver 706 as local oscillator.

The modulator 703 modulates the probe light under the control of the pattern generator 707 to generate a pulse sequence optical signal which is directionally coupled by the second coupler 704 and injected into the optical fiber 705. The pulse sequence optical signal may select different correlation patterns, such as Gray code, S code, etc., as needed.

The backscattered signal of the probe light during fiber optic transmission is passed through a second coupler 704 to a coherent receiver 706. The backscattered signal is coherent with the local oscillator at the coherent receiver 706, and the optical signal resulting from the coherent processing is converted to a digital signal input correlation processing unit 708. The digital signal and the symbol sequence generated by the pattern generator 707 are digitally correlated in the correlation processing unit 708 to be restored to the OTDR signal.

Different related patterns have different correlation algorithms. The general correlation pattern is composed of multiple sets of sequences. During the process, multiple sets of signals need to be correlated, reorganized, and finally restored to OTDR signals.

The method of coherent reception used in the embodiment of the invention improves the signal-to-noise ratio of the received signal; and the digital correlation operation is used to process the signal, which can effectively improve the dynamic range. Shown in Figure 7a is the basic structure of the associated coherent OTDR detection device. In order to achieve a better implementation effect, the related coherent OTDR detecting device can also be extended. The related coherent OTDR detecting apparatus after the extended variation will be described below by other embodiments.

Fig. 7b shows the structure of another related coherent OTDR detecting device. The detection device further includes a fill light laser 709 and a fill light modulator 710 with respect to Figure 7a. The fill light modulator 710 modulates the laser light emitted by the fill laser into a supplemental optical signal under the control of the associated pattern sequence output by the pattern generator 707; the second coupler 704 is used to The pulse sequence optical signal of 703 is combined with the supplementary optical signal to become a continuous optical detection signal of constant power and then input to the optical fiber to be tested. For existing submarine cable monitoring equipment, the optical power amplifiers in their optical power amplifiers and underwater line repeaters can only accept constant power optical inputs. The supplemental light laser 709 and the fill light modulator 710 are added, and the complementary light and the probe pulse light signal are combined to form a continuous power detection signal with constant power, which can be input to the above optical power amplifier, and is more suitable for the existing submarine cable monitoring equipment. The detection device further includes a fiber amplifier (711) located in the optical path of the second coupler (704) to the continuous optical detection signal of the fiber under test for power adjustment of the continuous optical detection signal.

Fig. 8 is a block diagram showing a related coherent OTDR detecting apparatus of a third embodiment of the present invention.

The continuous coherent light emitted by the probe laser 801 is split by the first coupler 802, a local light is passed through the attenuator 810 into the coherent receiver 811; the other is the Probing light. The probe light modulator 803 is entered. In contrast to Figure 7, Figure 8 adds an attenuator 810 to the optical path of the local oscillator. Because the power of the backscattered light is obviously much smaller than the local oscillator, if the local oscillator is not attenuated directly with the backscattered light, the coherence effect will be less noticeable. The function of the attenuator 810 is to reduce the power of the local oscillator light to the power of the backscattered light for better coherent reception.

The pattern generator 806 controls the probe light modulator 803 to modulate the probe light into a probe pulse light signal. It should be noted that only the modulation of the single pulse signal or the modulation of the pulse sequence can be performed as needed, and all are controlled by the pattern generator 806. Of course, if modulated into a single pulse signal, the correlated coherent OTDR detecting apparatus of this embodiment degenerates into a coherent OTDR in the prior art.

The laser light emitted by the fill laser 804 is a loading light. The pattern generator 806 also controls a fill light modulator 805 to modulate the supplemental light from the fill laser 804 to generate a supplemental light modulated signal. The complementary light and the wavelength of the aforementioned detection light are different. Under the control of the pattern generator 806, the complementary light and the pulse of the probe light form a complementary signal, both passing through the second coupler After the 807 combines, it is a continuous light detection signal with constant power. For existing submarine cable monitoring equipment, the optical power amplifier in the optical power amplifier and the underwater line repeater can only accept a constant power optical input. The detection pulse optical signal output by the probe light modulator 803 does not satisfy the requirement of constant power. Therefore, the fill light laser 804 and the fill light modulator 805 are added, and the complementary light detection signal is combined with the complementary light and the probe pulse light signal to form a continuous light detection signal of constant power, which can be input to the optical power amplifier. Since the complementary light is different from the wavelength of the probe light, the supplemental light is added without interference due to subsequent coherence and related processing.

The continuous optical detection signal is adjusted by an optical fiber amplifier (EDFA, Erbium-doped Optical Fiber Amplifer) 808 (adjusted as needed, different submarine cable system application scenarios have different power requirements), and the adjusted continuous optical detection signal Then passing through a scrambler (PS, Polarization Scrambler) 809 „ Since the detection light emitted by the high-coherence light source 801 is mostly polarized light, the coherence effect of the light with fixed polarization direction at the time of coherent reception will be affected (because of the orthogonal The polarized light cannot be coherent. The scrambler 809 randomly distributes the polarization direction of the probe light to avoid the occurrence of the incoherence of the polarization between the local oscillator and the backscattered light. The continuous optical detection signal passes through the third. The coupler 812 enters the fiber 814 of the submarine cable system. The backscattered light collected in the upstream direction of the fiber 814 passes through the fourth coupler 813 and is received by the coherent receiver 811. The backscattered light and the local oscillator are coherently received. The machine 811 is coherently received and photoelectrically converted. The electrical signal is then amplified by the signal amplifier 815, A The /D converter 816 performs analog-to-digital conversion, and is further processed by the digital processor 817 (for example, Band-Pass Filter (BPF), Envelope Detector, Low-Pass Filter (LPF, Low-Pass). Filter ) and so on, you get the OTDR signal.

Different from the general coherent OTDR technology, the embodiment scheme adds the relevant processing function, the pattern generator 806 sends four sets of unipolar Gray codes, and the digital processing of the signal performs correlation processing on the received signal, further Improve the signal-to-noise ratio of the OTDR signal, making it better for analyzing the operational status of the submarine cable system.

A fourth embodiment of the present invention further provides a method for detecting a correlated coherent optical time domain detection signal, and the flow thereof is as shown in FIG. 9, and includes the following steps:

Step 901: split the continuous coherent optical signal emitted by the coherent light source into two beams, the first beam as the probe light and the second beam as the local oscillator light;

Step 902: Modulate the probe light according to the relevant pattern sequence, generate a pulse sequence optical signal, and input the pulse sequence optical signal into the optical fiber to be tested; Step 903: Receive backscattered light from the fiber under test, perform coherent processing on the backscattered light and the local oscillator, and convert the optical signal obtained after the coherent processing into a digital signal;

Step 904: Perform digital correlation processing on the digital signal and the associated pattern sequence to obtain and output an optical time domain detection signal.

Preferably, the associated pattern sequence is a Gray code or an S code.

Preferably, the inputting the pulse sequence optical signal into the optical fiber to be tested includes:

Generating a supplemental optical signal under control of the associated pattern sequence;

The pulse sequence optical signal and the supplemental optical signal are combined into a continuous light detection signal of constant power, and the continuous optical detection signal is input to the optical fiber to be tested.

Preferably, before the step of inputting the continuous optical detection signal into the optical fiber to be tested, the method further includes: performing power adjustment on the continuous optical detection signal.

Preferably, before the step of inputting the continuous optical detection signal into the optical fiber to be tested, the method further includes: randomly distributing the polarization direction of the continuous optical detection signal.

Preferably, before the coherent processing of the backscattered light and the local oscillator light, the method further includes: performing attenuation processing on the local oscillator light.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalents, improvements, etc., which are made within the spirit and principles of the present invention, should be included in the present invention. Within the scope of protection.

Claims

Rights request

What is claimed is: 1. A detection apparatus for an optical time domain detection signal, comprising: a coherent light source (701), a first coupler (702), a modulator (703), a second coupler (704), and a coherent a receiver (706), a pattern generator (707), and an associated processing unit (708);

The coherent receiver (706) is configured to coherently process the local oscillator light from the first coupler (702) and the backscattered light from the second coupler, and convert the optical signal obtained by the coherent processing into a digital signal. Input the relevant processing unit (708);

The correlation processing unit (708) is configured to digitally correlate the digital signal from the coherent receiver (706) with the associated pattern sequence from the pattern generator (707) to obtain and output an optical time domain detection signal.

2. Detection apparatus according to claim 1, characterized in that the associated pattern sequence generated by the pattern generator (707) is a Gray code or an S code.

3. The detecting device according to claim 1, wherein the detecting device further comprises a fill light laser (709) and a fill light modulator (710), wherein the fill light modulator (710) is in the code The laser generated by the fill laser is modulated into a supplemental optical signal under the control of the associated pattern sequence output by the type generator (707);

The second coupler (704) is configured to combine the pulse sequence optical signal from the modulator (703) with the supplemental optical signal to become a continuous optical detection signal of constant power and input the optical fiber to be tested.

4. The detecting device according to claim 3, wherein the detecting device further comprises an optical fiber amplifier (711) located in the optical path of the second optical coupler (704) to the continuous optical detecting signal of the optical fiber to be tested, Power adjustment is performed on the continuous light detecting signal.

The detecting device according to claim 4, wherein the detecting device further comprises a scrambler located in an optical path of the optical fiber amplifier to the continuous optical detecting signal of the optical fiber to be tested, The polarization directions of the continuous optical detection signals output by the optical fiber amplifier are randomly distributed.

6. The detecting device according to claim 1, wherein the detecting device further comprises an attenuator for attenuating the local oscillator light output by the first coupler (702) and inputting to the coherent receiver. (706).

A method for detecting an optical time domain detection signal, comprising the steps of: dividing a continuous coherent optical signal emitted by a coherent light source into two beams, the first beam being the probe light and the second beam being the local oscillator light;

8. The method according to claim 7, wherein the correlation pattern sequence is a Gray code or an S code.

9. The method according to claim 7, wherein the inputting the pulse sequence optical signal into the optical fiber to be tested comprises:

The method according to claim 9, wherein the step of inputting the continuous optical detection signal into the optical fiber to be tested further comprises: randomly distributing a polarization direction of the continuous optical detection signal.

11. The method according to claim 7, wherein said backscattered light and said Before the local oscillator is coherently processed, the method further includes: performing attenuation processing on the local oscillator.