Optical fiber fault positioning device and method based on electric chaos and coherent detection
By combining electrical chaos with coherent detection technology, high-power, high-bandwidth chaotic signals are generated and coherent mixing and cross-correlation operations are performed, solving the problem of insufficient resolution and dynamic range of traditional OTDRs in optical fiber communication networks, and realizing high-precision optical fiber fault location.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-26
- Publication Date
- 2026-03-13
AI Technical Summary
Traditional OTDRs suffer from insufficient resolution and dynamic range in fiber optic communication networks, making it difficult to accurately locate fault points in passive optical networks, especially in situations with high split ratios and short-distance cabling, resulting in slow operation and maintenance response speeds and high costs.
The fiber optic fault location device, which combines electrical chaos and coherent detection technology, generates a high-power, high-bandwidth, and easily integrated chaotic detection signal by combining a narrow-linewidth laser, an optical modulation module, an electrical chaotic signal generation module, an optical coherent detection module, and a signal processing module. It then performs coherent mixing and cross-correlation operations to identify the fault point.
It achieves high-resolution, large dynamic range and high stability fiber optic fault location, overcoming the problems of low signal power, complex optical path and high cost of traditional OTDR, and improving the accuracy and efficiency of fault location.
Smart Images
Figure CN121664293A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical fiber communication technology, and in particular to an optical fiber fault location device and method based on electrical chaos and coherent detection. Background Technology
[0002] Optical Time Domain Reflectometers (OTDRs) are crucial tools for link diagnosis, maintenance, and fault location in fiber optic communication networks. Their performance directly impacts network operation and maintenance efficiency and cost. However, in optical access networks (especially in Passive Optical Network (PON) architectures), the insufficient sensitivity and resolution of traditional OTDRs have become key factors restricting the speed and accuracy of operation and maintenance responses. Specifically, the optical distribution network (ODN) in the "last mile" of a PON network is characterized by dense splitters and complex branches. High splitting ratios (such as 1:8 and above) introduce significant attenuation exceeding 10dB, making it difficult for traditional OTDRs, due to their limited dynamic range, to effectively penetrate the splitters to detect weak backscattered signals from distant branches. Simultaneously, user-end cabling is often short-distance, with extremely close proximity of events such as connectors and splices. The low spatial resolution of traditional OTDRs can cause these critical event points to be obscured by "blind spots," making accurate location impossible. This technological shortcoming leads to a significant delay in fault location: operators often have to passively wait for user complaints and spend hours or even longer in subsequent troubleshooting, causing not only user dissatisfaction but also significant damage to the operator's service reputation and wasted manpower. The technical bottleneck of traditional OTDRs is rooted in their basic principles. They typically use a single laser pulse as the detection signal, and there is an inherent contradiction between spatial resolution and dynamic range. On the one hand, spatial resolution depends on the pulse width; the narrower the pulse width, the higher the resolution. On the other hand, limited by the peak power of the laser, to increase the incident light energy and thus the measurement distance, a wider pulse must be used, inevitably leading to a decrease in resolution. Typical OTDRs have detection pulse widths between 10 ns and 1 μs, corresponding to spatial resolutions of only 1 to 100 meters, far from meeting the high-precision fault monitoring requirements of modern PON networks.
[0003] To overcome these limitations, various technical solutions have been proposed, but all have significant drawbacks: While ultrashort pulse combined with photon counting technology can improve resolution, it suffers from short measurement distances, low signal-to-noise ratios, and expensive and complex systems (as described by Legré M et al.). Low-coherence optical reflection (OLCR) can achieve high-precision positioning through interference principles, but its measurement distance is limited by the mechanical scanning range of the reference arm, typically only suitable for short-range detection within devices, and cannot meet the needs of remote line monitoring. Pseudo-random code modulation technology: by encoding the probe light, it balances resolution and distance under certain conditions. However, this scheme requires expensive high-speed electrical random code modulators, resulting in high costs, and the modulation rate is limited by the bandwidth of electronic devices, leading to performance bottlenecks (as described by Xiao Long et al.).
[0004] In recent years, chaotic optical time-domain reflectometry (OTDR) has offered a new approach to resolving the contradiction between resolution and distance. This technique utilizes broadband chaotic lasers as the detection signal, and by cross-correlation processing of the reference signal and the echo signal, it can achieve high spatial resolution independent of the detection distance. Since its initial verification by Wang Yuncai et al., this technique has undergone significant development. For example, M Li et al. achieved a resolution of 1 cm at a distance of 76.54 km, and Zhang LM et al. even achieved an extremely high resolution of 2.6 mm. However, most existing chaotic OTDR schemes are based on generating chaotic lasers through optical feedback (such as using semiconductor lasers with external cavity feedback). The signal power generated by this "optical chaos" scheme is typically low (milliwatt level), limiting the dynamic range of the system, and the optical path structure is complex, posing challenges to stability and integration. On the other hand, coherent detection technology has proven to be an effective way to improve detection sensitivity and dynamic range. As shown by S Furukawa et al., coherent detection, by introducing local oscillating light, can provide significant coherent gain, effectively suppress noise, and bring the system sensitivity close to the quantum limit, thereby achieving a large dynamic range measurement exceeding 42 dB.
[0005] In summary, while OTDR solutions based on optical chaos solve the high-resolution problem, they suffer from shortcomings in signal power, dynamic range, and system integration. Coherent detection technology, although it can significantly improve sensitivity, cannot be combined with a chaotic signal source that combines high power, high bandwidth, easy integration, and controllable cost. Therefore, there is an urgent need for a method that can deeply integrate high-performance chaotic signal generation mechanisms with mature coherent detection technology, thereby maintaining ultra-high spatial resolution while overcoming the limitations of traditional OTDRs in dynamic range, sensitivity, and cost. Summary of the Invention
[0006] The purpose of this invention is to address at least one deficiency in the prior art and to provide an optical fiber fault location device and method based on electrical chaos and coherent detection. This invention achieves a solution with high resolution, large dynamic range, high stability and good integration potential by integrating electrical chaos and coherent detection.
[0007] To achieve the above objectives, in a first aspect, the present invention provides an optical fiber fault location device based on electro-chaos and coherent detection. The device includes: a narrow-linewidth laser, an optical beam splitter, an optical modulation module, an optical fiber under test, an electro-chaos signal generation module, an optical coherent detection module, and a signal processing module. The output end of the narrow-linewidth laser is connected to the input segment of the optical beam splitter. The first output end of the optical beam splitter is connected to the first input end of the optical modulation module, and the second output end is connected to the first input end of the optical coherent detection module. The second input end of the optical modulation module is connected to the first output end of the electro-chaos signal generation module, and is used to process the broadband chaotic electrical signal output by the electro-chaos signal generation module. The system modulates a continuous optical carrier from a narrow-linewidth laser to output chaotic probe light. The second output of the electro-chaotic signal generation module is connected to the first input of the signal processing module, and the electro-chaotic signal generation module outputs a broadband chaotic electrical signal. The second input of the optical coherent detection module is connected to the output of the echo signal from the fiber under test, and is used to coherently mix the echo signal with the local reference light from the beam splitter, and output a differential electrical signal. The second input of the signal processing module is connected to the output of the optical coherent detection module, and is used to perform cross-correlation calculations on the broadband chaotic electrical signal and the differential electrical signal, and determine fault information in the fiber optic link based on the cross-correlation results.
[0008] Preferably, the optical modulation module includes an intensity modulator and an optical circulator connected in sequence. The first output terminal of the optical beam splitter is connected to the first input terminal of the intensity modulator, and the second input terminal of the intensity modulator is connected to the first output terminal of the electro-chaotic signal generation module. The first port of the optical circulator is connected to the optical output terminal of the intensity modulator, its second port is connected to the optical fiber under test, and its third port is used to output the echo signal to the optical coherence detection module.
[0009] Preferably, the chaotic signal generation module includes a chaotic signal source and a power divider connected in sequence. The first output terminal of the power divider is connected to the second input terminal of the intensity modulator, and the second output terminal is connected to the first input terminal of the signal processing module. The chaotic signal source is an autonomous Boolean chaotic network constructed based on digital logic gate circuits.
[0010] Preferably, the autonomous Boolean chaotic network includes a three-input XOR gate and three feedback paths with different delay times.
[0011] Preferably, the optical coherence detection module includes a coupler and a photoelectric balance detector connected in sequence. The first input terminal of the coupler is connected to the second output terminal of the beam splitter, and the second input terminal is connected to the output terminal of the echo signal of the optical fiber under test. The output terminal of the photoelectric balance detector is connected to the second input terminal of the signal processing module.
[0012] Preferably, the signal processing module includes a data acquisition card and a processor connected in sequence. The first input terminal of the data acquisition card is connected to the second output terminal of the power divider, and the second input terminal is connected to the photoelectric balance detector, for synchronously acquiring the broadband chaotic electrical signal and the differential electrical signal; the processor is used to perform the cross-correlation calculation and fault information determination steps.
[0013] Preferably, the signal processing module is further configured to: During the system initialization phase, the reference cross-correlation curve under fault-free conditions is obtained and its peak position is recorded; During the monitoring phase, the real-time acquired cross-correlation curve is compared with the reference cross-correlation curve. If a new cross-correlation peak appears outside the peak position, a reflection fault is determined to exist, and the distance to the fault point is calculated based on the position of the new cross-correlation peak. If the amplitude of the peak position decreases significantly or disappears, a loss fault is determined to exist.
[0014] Preferably, the signal processing module is further configured to: when multiple new cross-correlation peaks appear in the cross-correlation curve, sort them according to the amplitude of each peak and output the corresponding multiple fault point distance information in sequence.
[0015] In a second aspect, the present invention also provides a fiber optic fault location method based on electrical chaos and coherent detection, the location method being based on the location device described in the first aspect, comprising: Generate broadband chaotic electrical signals and continuous optical carriers; The broadband chaotic electrical signal is used to modulate the continuous optical carrier to generate chaotic probe light, which is then injected into the optical fiber under test. The echo signal from the optical fiber under test is coherently mixed with the local reference light and balanced detection is performed to obtain a differential electrical signal. A cross-correlation operation is performed on the broadband chaotic electrical signal and the differential electrical signal to obtain a cross-correlation curve; The cross-correlation curves are analyzed to determine fault information in the fiber optic link.
[0016] Furthermore, the analysis of the cross-correlation curve specifically includes: comparing the real-time acquired cross-correlation curve with a pre-stored fault-free reference curve; based on the comparison results, identifying reflective faults and / or wear-type faults, and calculating the location of the fault point.
[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention generates a high-power, high-bandwidth, and easily integrated chaotic detection signal through an electro-chaotic signal generation module. This electro-chaotic signal is then fused with an optical coherent detection mechanism. The photoelectric coherent detection effectively suppresses common-mode noise, and a local reference light provides coherent gain, bringing the device's sensitivity close to the shot noise limit. This collaborative design avoids the problem of spatial resolution and dynamic range being mutually constrained in traditional OTDRs. Simultaneously, this device overcomes the shortcomings of existing chaotic OTDR solutions, such as low signal power, complex optical paths, and high costs, providing a fiber optic fault location solution that combines high resolution, large dynamic range, high stability, and good integration potential. Attached Figure Description
[0018] Figure 1 This is a structural diagram of an optical fiber fault location device based on electrical chaos and coherent detection according to Embodiment 1 of the present invention. Figure 2 This is a structural diagram of the photoelectric balance detector of Embodiment 1 of this aspect; Figure 3 This is a structural diagram of the autonomous Boolean network of Embodiment 1 of the present invention; Figure 4 This is a flowchart of an optical fiber fault location method based on electrical chaos and coherent detection, according to Embodiment 2 of the present invention.
[0019] Explanation of reference numerals: 1. Narrow linewidth laser; 2. Optical beam splitter; 3. Intensity modulator; 4. Optical circulator; 5. Fiber under test; 6. Mixed... 7. Chaotic signal source; 8. Power divider; 9. Coupler; 10. Photoelectric balance detector; 11. First photodiode; 22. Second photodiode. 93. Photodiode; 94. I / V converter; 10. Electrical amplifier; 11. Data acquisition card; 12. Processor. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0021] Example 1 Please see Figure 1This invention provides a preferred embodiment of an optical fiber fault location device based on electrical chaos and coherent detection. The device includes: a narrow-linewidth laser 1, an optical beam splitter 2, an optical modulation module, an optical fiber under test 5, an electrical chaos signal generation module, an optical coherent detection module, and a signal processing module. The output of the narrow-linewidth laser 1 is connected to the input segment of the optical beam splitter 2. The first output of the optical beam splitter 2 is connected to the first input of the optical modulation module, and the second output is connected to the first input of the optical coherent detection module. The second input of the optical modulation module is connected to the first output of the electrical chaos signal generation module, used to process the broadband chaotic electrical signal output by the electrical chaos signal generation module. A continuous optical carrier from a narrow-linewidth laser is modulated to output chaotic probe light; the second output of the electro-chaotic signal generation module is connected to the first input of the signal processing module, and the electro-chaotic signal generation module is used to output a broadband chaotic electrical signal; the second input of the optical coherent detection module is connected to the output of the echo signal of the fiber under test 5, and is used to coherently mix the echo signal with the local reference light from the beam splitter 2, and output a differential electrical signal; the second input of the signal processing module is connected to the output of the optical coherent detection module, and is used to perform cross-correlation calculation on the broadband chaotic electrical signal and the differential electrical signal, and determine the fault information in the fiber link based on the cross-correlation result.
[0022] In this embodiment, a narrow-linewidth laser 1 generates continuous light, which is processed by an optical beam splitter 2 to output two signals: a continuous optical carrier signal and a local reference light. The continuous optical carrier signal is transmitted to an optical modulation module, which modulates it using a broadband chaotic electrical signal output by an electrical chaotic signal generation module to output a chaotic probe light. The chaotic probe light is injected into the fiber under test 5. Under normal, fault-free conditions, the chaotic probe light propagates in the fiber under test, only reflecting at the fiber end to form a reflected echo. The echo returns along the original path, outputting an echo signal. An optical coherent detection module coherently mixes the echo signal with the local reference light from the beam splitter 2 and outputs a differential electrical signal. A signal processing module performs cross-correlation calculations on the broadband chaotic electrical signal and the differential electrical signal, and determines fault information in the fiber link based on the cross-correlation results.
[0023] In this embodiment, the wavelength of the narrow-linewidth laser 1 is adjustable in the C-band, and its output power is adjustable; the beam splitter 2 is a 50:50 optical beam splitter. This embodiment generates a high-power, high-bandwidth, and easily integrated chaotic detection signal through an electro-chaotic signal generation module. This electro-chaotic signal is then fused with an optical coherent detection mechanism. The photoelectric coherent detection effectively suppresses common-mode noise, and a local reference light provides coherent gain, bringing the device sensitivity close to the shot noise limit. This collaborative design avoids the problem of spatial resolution and dynamic range being mutually constrained in traditional OTDRs. Simultaneously, this device overcomes the shortcomings of existing chaotic OTDR solutions, such as low signal power, complex optical paths, and high costs, providing a fiber optic fault location solution that combines high resolution, large dynamic range, high stability, and good integration potential.
[0024] Preferably, the optical modulation module includes an intensity modulator 3 and an optical circulator 4 connected in sequence. In this case, the connection relationship between the components is as follows: the first output terminal of the optical beam splitter 2 is connected to the first input terminal of the intensity modulator 3, and the second input terminal of the intensity modulator 3 is connected to the first output terminal of the electro-chaotic signal generation module; the first port of the optical circulator 4 is connected to the optical output terminal of the intensity modulator 3, its second port is connected to the optical fiber under test 5, and its third port is used to output the echo signal to the optical coherence detection module.
[0025] Preferably, the electrical chaotic signal generation module includes a chaotic signal source 6 and a power divider 7 connected in sequence. The first output terminal of the power divider 7 is connected to the second input terminal of the intensity modulator 3, and the second output terminal is connected to the first input terminal of the signal processing module. Furthermore, the chaotic signal source 6 is an autonomous Boolean chaotic network constructed based on digital logic gate circuits. Further, please refer to... Figure 3 The autonomous Boolean chaotic network includes a three-input XOR gate and three feedback paths with different delay times. The output signal of the XNOR is fed back to the input through the three different paths. , and These represent the transmission delay times of the path, respectively. The transmission delay time can be controlled by cascading NOT gates of varying numbers (n1, n2, and n3). This invention uses the Altera MAX II series EPM1270T chip. When n1 equals 2, n2 equals 6, and n3 equals 10, the Boolean chaotic circuit can generate a chaotic signal with a maximum amplitude of approximately 2.1V; a 10dB bandwidth of up to 500MHz, and a very flat signal; the autocorrelation curve shows... Its functional shape and lack of periodic sidelobes make it ideal for use with high-resolution OTDRs.
[0026] Preferably, the optical coherence detection module includes a coupler 8 and a photoelectric balanced detector 9 connected in sequence. The first input terminal of the coupler 8 is connected to the second output terminal of the beam splitter 2, and the second input terminal is connected to the output terminal of the echo signal of the optical fiber under test 5. The output terminal of the photoelectric balanced detector 9 is connected to the second input terminal of the signal processing module. In this embodiment, please refer to... Figure 2 A 50:50 coupler 8 couples the local reference light and the echo signal, causing interference between the two lights. The phase difference between the two output light intensities after interference is pi, making them a differential signal pair. The balanced photodetector uses two highly matched and consistent first photodiodes 91 and 92 for photoelectric conversion. After entering the balanced detector, the signals are subtracted, doubling the amplitude. Since the two noises are common-mode noise and identical, their subtraction equals zero. This doubles the signal, reduces noise, and improves the signal-to-noise ratio by more than 3dB. The subtracted signal then passes through an I / V converter 93 and an amplifier 94, ultimately outputting an electrical signal.
[0027] Preferably, the signal processing module includes a data acquisition card 10 and a processor 11 connected in sequence. The first input terminal of the data acquisition card is connected to the second output terminal of the power divider 7, and the second input terminal is connected to the photoelectric balance detector 9, for synchronously acquiring the broadband chaotic electrical signal and the differential electrical signal. The processor is used to execute the cross-correlation calculation and fault information determination steps, and the processor 11 can be a computer. Further, the signal processing module is also used to: during the system initialization phase, acquire a reference cross-correlation curve under fault-free conditions and record its peak position; during the monitoring phase, compare the real-time acquired cross-correlation curve with the reference cross-correlation curve; if a new cross-correlation peak appears outside the peak position, a reflection-type fault is determined, and the fault point distance is calculated based on the position of the new cross-correlation peak; if the amplitude of the peak position decreases significantly or disappears, a loss-type fault is determined. Simultaneously, the signal processing module is also used to: when multiple new cross-correlation peaks appear in the cross-correlation curve, sort them according to the amplitude of each peak and output the corresponding multiple fault point distance information sequentially. Specifically, the fiber optic link fault condition is determined based on the comparison results. 1. If a new correlation peak appears outside the original reference peak in the real-time correlation curve, it indicates that a reflective fault has occurred in the fiber optic link. The position of the new correlation peak corresponds to the location of the reflective fault point. 2. If the amplitude of the original reference peak in the real-time correlation curve decreases significantly, or the original reference peak disappears directly, it indicates that there is a loss-type fault in the optical fiber link, and the area corresponding to the original reference peak is the area affected by the loss-type fault. 3. Based on the location of the newly emerging related peaks and parameters such as the speed of light propagation in optical fibers, the distance from the fault point to the central office is calculated. At the same time, the corresponding event log is automatically generated on the system monitoring interface, recording information such as the time of the fault occurrence, the type of the fault, and the distance of the fault point. 4. If multiple new correlation peaks appear simultaneously in the real-time correlation curve, they are sorted according to the magnitude of each new peak, and the distance information of multiple fault points is output in sequence according to the sorting result, so as to realize the location of multiple faults with a single measurement. Throughout the monitoring process, the coherent gain and noise suppression balanced detection structure effectively suppresses common-mode noise in the system, reducing noise interference with the monitoring signal. The local reference light enhances the power of the echo signal, enabling the system to operate within the shot noise limit and ensuring signal detection sensitivity. Utilizing the delta-type autocorrelation characteristics of chaotic signals, a narrow correlation peak is obtained, which significantly improves the system's spatial resolution and allows for more precise fault location. By performing multiple averaging processes on the monitoring data and employing digital mismatch filtering technology, the intensity of the correlation sidelobes is reduced, improving the system's signal-to-noise ratio and extending its dynamic range, ensuring accurate monitoring of the fiber optic link status under varying signal intensities.
[0028] Example 2 Please see Figure 4 An embodiment of the present invention provides a fiber optic fault location method based on electrical chaos and coherent detection, comprising the following steps: S1: Generate broadband chaotic electrical signals and continuous optical carriers; S2: Modulate the continuous optical carrier using the broadband chaotic electrical signal to generate chaotic probe light and inject it into the optical fiber under test; S3: The echo signal from the optical fiber under test is coherently mixed with the local reference light and balanced detection is performed to obtain a differential electrical signal; S4: Perform cross-correlation calculation on the broadband chaotic electrical signal and the differential electrical signal to obtain the cross-correlation curve; S5: Analyze the cross-correlation curves to determine fault information in the fiber optic link. Specifically, analyzing the cross-correlation curves includes: comparing the real-time acquired cross-correlation curves with pre-stored fault-free reference curves; based on the comparison results, identifying reflection-type faults and / or loss-type faults, and calculating the location of the fault point. It should be noted that after the detection line starts operating, the system enters a periodic monitoring state, continuously repeating steps S3-S5 to continuously obtain real-time correlation curves; after each real-time correlation curve is obtained, it is compared and analyzed with the reference position recorded in step S4, and the fiber optic link fault condition is determined based on the comparison results.
[0029] The method proposed in this embodiment is based on the device proposed in Embodiment 1. Therefore, the options proposed in Embodiment 1 are also applicable to this embodiment. To avoid repetition, they will not be described again here.
[0030] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A fiber optic fault location device based on electrical chaos and coherent detection, characterized in that, The device includes: a narrow linewidth laser (1), an optical beam splitter (2), an optical modulation module, an optical fiber under test (5), an electrical chaotic signal generation module, an optical coherence detection module, and a signal processing module. The output end of the narrow linewidth laser (1) is connected to the input segment of the optical beam splitter (2), the first output end of the optical beam splitter (2) is connected to the first input end of the optical modulation module, and the second output end is connected to the first input end of the optical coherence detection module. The second input terminal of the optical modulation module is connected to the first output terminal of the electrical chaotic signal generation module, and is used to modulate the continuous optical carrier from the narrow linewidth laser according to the broadband chaotic electrical signal output by the electrical chaotic signal generation module, and output chaotic detection light. The second output terminal of the electro-chaotic signal generation module is connected to the first input terminal of the signal processing module, and the electro-chaotic signal generation module is used to output a broadband chaotic electrical signal. The second input terminal of the optical coherent detection module is connected to the output terminal of the echo signal of the optical fiber under test (5), and is used to coherently mix the echo signal with the local reference light from the beam splitter (2) and output a differential electrical signal. The second input terminal of the signal processing module is connected to the output terminal of the optical coherence detection module, and is used to perform cross-correlation calculation on the broadband chaotic electrical signal and the differential electrical signal, and determine the fault information in the optical fiber link based on the cross-correlation result.
2. The fiber optic fault location device based on electrical chaos and coherent detection according to claim 1, characterized in that, The optical modulation module includes an intensity modulator (3) and an optical circulator (4) connected in sequence. The first output terminal of the optical beam splitter (2) is connected to the first input terminal of the intensity modulator (3), and the second input terminal of the intensity modulator (3) is connected to the first output terminal of the electro-chaotic signal generation module. The first port of the optical circulator (4) is connected to the optical output terminal of the intensity modulator (3), its second port is connected to the optical fiber under test (5), and its third port is used to output the echo signal to the optical coherence detection module.
3. The fiber optic fault location device based on electrical chaos and coherent detection according to claim 2, characterized in that, The electrical chaotic signal generation module includes a chaotic signal source (6) and a power divider (7) connected in sequence. The first output terminal of the power divider (7) is connected to the second input terminal of the intensity modulator (3), and the second output terminal is connected to the first input terminal of the signal processing module. The chaotic signal source (6) is an autonomous Boolean chaotic network constructed based on digital logic gate circuits.
4. The fiber optic fault location device based on electrical chaos and coherent detection according to claim 3, characterized in that, The autonomous Boolean chaotic network includes a three-input XOR gate and three feedback paths with different delay times.
5. The fiber optic fault location device based on electrical chaos and coherent detection according to claim 4, characterized in that, The optical coherence detection module includes a coupler (8) and a photoelectric balance detector (9) connected in sequence. The first input end of the coupler (8) is connected to the second output end of the beam splitter (2), and the second input end is connected to the output end of the echo signal of the optical fiber (5) under test. The output end of the photoelectric balance detector (9) is connected to the second input end of the signal processing module.
6. The fiber optic fault location device based on electrical chaos and coherent detection according to claim 5, characterized in that, The signal processing module includes a data acquisition card (10) and a processor (11) connected in sequence. The first input terminal of the data acquisition card is connected to the second output terminal of the power divider (7), and the second input terminal is connected to the photoelectric balance detector (9) for synchronously acquiring the broadband chaotic electrical signal and the differential electrical signal. The processor is used to perform the cross-correlation calculation and fault information determination steps.
7. The fiber optic fault location device based on electrical chaos and coherent detection according to claim 6, characterized in that, The signal processing module is also used for: During the system initialization phase, the reference cross-correlation curve under fault-free conditions is obtained and its peak position is recorded; During the monitoring phase, the real-time acquired cross-correlation curve is compared with the reference cross-correlation curve. If a new cross-correlation peak appears outside the peak position, a reflection fault is determined to exist, and the distance to the fault point is calculated based on the position of the new cross-correlation peak. If the amplitude of the peak position decreases significantly or disappears, a loss fault is determined to exist.
8. The fiber optic fault location device based on electrical chaos and coherent detection according to claim 7, characterized in that, The signal processing module is also used to: when multiple new cross-correlation peaks appear in the cross-correlation curve, sort them according to the amplitude of each peak and output the corresponding distance information of multiple fault points in sequence.
9. A fiber optic fault location method based on electrical chaos and coherent detection, characterized in that, The positioning method is based on the positioning device according to any one of claims 1-8, comprising: Generate broadband chaotic electrical signals and continuous optical carriers; The broadband chaotic electrical signal is used to modulate the continuous optical carrier to generate chaotic probe light, which is then injected into the optical fiber under test. The echo signal from the optical fiber under test is coherently mixed with the local reference light and balanced detection is performed to obtain a differential electrical signal. A cross-correlation operation is performed on the broadband chaotic electrical signal and the differential electrical signal to obtain a cross-correlation curve; The cross-correlation curves are analyzed to determine fault information in the fiber optic link.
10. The fiber optic fault location method based on electrical chaos and coherent detection according to claim 9, characterized in that, The analysis of the cross-correlation curve specifically includes: comparing the real-time acquired cross-correlation curve with the pre-stored fault-free reference curve; based on the comparison results, identifying reflection-type faults and / or wear-type faults, and calculating the location of the fault point.