Forward transmission distributed optical fiber sensing detection method and system based on chirp modulation, terminal and storage medium

Abstract

The invention relates to the field of optical fiber sensing detection, and discloses a forward transmission distributed optical fiber sensing detection method and system based on chirp modulation, a terminal and a storage medium, and the method comprises the steps: obtaining a sensing detection task of a sensing optical fiber, obtaining a single-frequency continuous optical signal and a radio frequency signal according to the sensing detection task, performing chirp modulation on the single-frequency continuous optical signal according to the radio frequency signal to obtain a plurality of modulated optical signals; superposing all the modulated light signals to obtain a sweep-frequency light field, and dividing the sweep-frequency light field to obtain a sensing light field and a reference light field; performing interference processing on a target sensing light field output by the sensing optical fiber and the reference light field to obtain beat frequency interference light intensity, and performing filtering to obtain a target beat frequency interference signal; and performing demodulation processing on the target beat frequency interference signal to obtain a light field phase change, and performing vibration positioning on the sensing optical fiber to obtain an optical fiber vibration position so as to obtain a sensing detection result. According to the invention, not only is the detection cost reduced, but also the vibration on the sensing optical fiber can be accurately positioned.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber sensing detection, and in particular to a forward transmission distributed optical fiber sensing detection method, system, terminal and computer-readable storage medium based on chirp modulation. Background Art

[0002] Currently, fiber optic sensing technology can be used to measure numerous parameters in physics, chemistry, biology, and other fields, providing novel detection methods for the development of natural sciences. As a novel vibration sensing technology that integrates both signal sensing and transmission, distributed fiber optic vibration sensing technology enables continuous, distributed measurement of vibration events along an optical fiber by directly sensing and detecting light wave signals.

[0003] Distributed fiber optic vibration sensing technology can be roughly divided into two structures according to its sensing mechanism. One is a distributed vibration fiber optic sensing system based on backscattering in optical fiber, such as the optical time domain reflectometry system (OTDR) and the optical frequency domain reflectometry system (OFDR). This distributed fiber optic sensing system uses the time-of-flight method for positioning and has the characteristics of high spatial resolution and high positioning accuracy. However, due to the very weak Rayleigh backscattering in the optical fiber, its sensing distance is limited (for example, the sensing distance is less than 100 km); the other is a distributed vibration fiber optic sensing system based on forward transmission of light (FTDVS). The FTDVS uses forward continuous light in an optical fiber as the detection light, offering the advantages of long transmission distance, large dynamic range, and broadband response. However, existing FTDVS still face multiple bottlenecks. For example, the need for bidirectional transmission for positioning necessitates the installation of a ring-shaped sensing fiber in most systems, significantly increasing the cost of laying the optical fiber. Furthermore, to avoid the influence of backward Rayleigh scattering over long distances, the bidirectional transmission structure requires the use of dual-core optical fibers or dual-wavelength light sources, increasing hardware costs.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] The main purpose of the present invention is to provide a forward transmission distributed optical fiber sensing detection method, system, terminal and storage medium based on chirp modulation, aiming to solve the problems of inaccurate detection results obtained by sensing the entire sensing optical fiber through optical wave signals in the existing technology, resulting in the inability to accurately locate vibrations on the entire sensing optical fiber, thereby failing to detect intrusion events in a timely manner, and the high cost of sensing detection.

[0006] To achieve the above object, the present invention provides a forward transmission distributed optical fiber sensing detection method based on chirp modulation, the forward transmission distributed optical fiber sensing detection method based on chirp modulation comprising the following steps: Acquiring a sensing detection task of a sensing optical fiber, acquiring a single-frequency continuous optical signal and a radio frequency signal according to the sensing detection task, and chirping modulating the single-frequency continuous optical signal according to the radio frequency signal to obtain a plurality of modulated optical signals; Superimposing all the modulated optical signals to obtain a frequency-sweeping optical field, dividing the frequency-sweeping optical field to obtain a sensing light field and a reference light field, and inputting the sensing light of the sensing light field into the sensing optical fiber; receiving a target sensing light field output by the sensing optical fiber, performing interference processing on the target sensing light field and the reference light field to obtain a beat frequency interference light intensity, and performing filtering processing on the beat frequency interference light intensity to obtain a target beat frequency interference signal; The target beat frequency interference signal is demodulated to obtain a light field phase change, the sensing optical fiber is vibration-positioned according to the light field phase change to obtain an optical fiber vibration position, and a sensing detection result is obtained according to the optical fiber vibration position.

[0007] Optionally, in the forward transmission distributed optical fiber sensing detection method based on chirp modulation, the radio frequency signal includes a first chirped frequency sweep signal and a second chirped frequency sweep signal, and the modulated optical signal includes a first I-channel modulated optical signal, a second I-channel modulated optical signal, a first Q-channel modulated optical signal, and a second Q-channel modulated optical signal; The chirp-modulating the single-frequency continuous optical signal according to the radio frequency signal to obtain a plurality of modulated optical signals specifically includes: Performing phase-opposite modulation on the single-frequency continuous optical signal and the first chirped swept-frequency signal through a first I-channel modulation channel to obtain a first I-channel modulated optical signal; Performing phase-opposite modulation on the single-frequency continuous optical signal and the first chirped swept-frequency signal through a second I-channel modulation channel to obtain a second I-channel modulated optical signal; Modulating the single-frequency continuous optical signal and the second chirped swept-frequency signal through a first Q-channel modulation channel to obtain a first Q-channel modulated optical signal; The single-frequency continuous optical signal and the second chirped frequency-sweep signal are modulated through a second Q-path modulation channel to obtain a second Q-path modulated optical signal.

[0008] Optionally, in the forward transmission distributed optical fiber sensing detection method based on chirp modulation, the target sensing light field includes a Rayleigh backscattered light field, a first light field, and a second light field; The interfering process of the target sensing light field and the reference light field to obtain a beat frequency interference light intensity, and filtering the beat frequency interference light intensity to obtain a target beat frequency interference signal specifically includes: performing light intensity calculation based on the Rayleigh backscattered light field and the reference light field to obtain the Rayleigh backscattered light intensity; Performing light intensity calculation based on the first light field and the reference light field to obtain a first light intensity; Performing light intensity calculation based on the second light field and the reference light field to obtain a second light intensity; The Rayleigh backscattered light intensity, the first light intensity and the second light intensity are superimposed to obtain a beat frequency interference light intensity, and a plurality of bandpass filters with different frequencies are set; Performing signal extraction on the beat frequency interference light intensity according to the passbands of all the bandpass filters to obtain a Rayleigh backscattered beat frequency interference signal, a first beat frequency interference signal, and a second beat frequency interference signal; The Rayleigh backscattered beat frequency interference signal is filtered to obtain a processing result, and the first beat frequency interference signal and the second beat frequency interference signal are combined according to the processing result to obtain a target beat frequency interference signal.

[0009] Optionally, in the forward transmission distributed optical fiber sensing detection method based on chirp modulation, the light intensity calculation is performed based on the Rayleigh backscattered light field and the reference light field, specifically: ; The light intensity calculation according to the first light field and the reference light field is specifically performed as follows: ; The light intensity calculation according to the second light field and the reference light field is specifically performed as follows: ; in, is the Rayleigh backscattered light intensity, is the propagation time of the sensing light in the sensing optical fiber for one round trip, is the sensing fiber length, is the propagation time, is the light frequency output by the light source, is the starting frequency of the sweep, is the beat frequency of the Rayleigh backscattered beat frequency interference signal, is the sweep time, is the sweep speed, is the phase change caused by external disturbance, is the first light intensity, is the propagation time of the sensing light in the first delay fiber, is the carrier frequency of the first beat frequency interference signal, is the second light intensity, is the propagation time of the sensing light in the second delay optical fiber.

[0010] Optionally, in the forward transmission distributed optical fiber sensing detection method based on chirp modulation, the light field phase change includes a first light field phase change and a second light field phase change; The demodulating the target beat frequency interference signal to obtain a light field phase change specifically includes: Performing signal construction on a first beat frequency interference signal of the target beat frequency interference signal to obtain a first analytical signal, and performing component calculation on the first analytical signal to obtain a first I component and a first Q component; Performing signal construction on a second beat frequency interference signal of the target beat frequency interference signal to obtain a second analytical signal, and performing component calculation on the second analytical signal to obtain a second I component and a second Q component; A first light field phase change is obtained according to the first I component and the first Q component, and a second light field phase change is obtained according to the second I component and the second Q component.

[0011] Optionally, in the chirp-modulated forward transmission distributed optical fiber sensing detection method, the signal construction of the first beat frequency interference signal of the target beat frequency interference signal is specifically performed as follows: ; The signal construction of the second beat frequency interference signal of the target beat frequency interference signal is specifically as follows: ; in, is the first analytical signal, is the first beat frequency interference signal, is an imaginary expression, is the Hilbert transform result of the first beat frequency interference signal, is the amplitude of the first analytical signal, is the carrier frequency of the first beat frequency interference signal, is the sweep time, is the phase change of the first light field, is the second analytical signal, is the second beat frequency interference signal, is the Hilbert transform result of the second beat frequency interference signal, is the amplitude of the second analytical signal, is the carrier frequency of the second beat frequency interference signal, is the phase change of the second light field.

[0012] Optionally, the forward transmission distributed optical fiber sensing detection method based on chirp modulation, wherein the vibration positioning of the sensing optical fiber is performed according to the phase change of the light field to obtain the optical fiber vibration position, and the sensing detection result is obtained according to the optical fiber vibration position, specifically includes: performing phase reconstruction on the first light field phase change and the second light field phase change to obtain a first phase and a second phase, and performing cross-correlation processing on the first phase and the second phase to obtain a second path propagation time; Performing vibration position detection based on the second path propagation time to obtain the optical fiber vibration position, and obtaining a sensing detection result based on the optical fiber vibration position; The vibration position detection according to the second path propagation time is specifically performed as follows: ; in, is the optical fiber vibration position, is the propagation time of the sensing light in the sensing optical fiber for one round trip, Second path propagation time, is the propagation time of the sensing light in the second delay fiber, is the refractive index of the sensing fiber, is the speed of light in a vacuum.

[0013] Optionally, the forward transmission distributed optical fiber sensing detection method based on chirp modulation, wherein the forward transmission distributed optical fiber sensing detection system based on chirp modulation includes: a signal modulation module, configured to obtain a sensing detection task of the sensing optical fiber, obtain a single-frequency continuous optical signal and a radio frequency signal according to the sensing detection task, and chirp-modulate the single-frequency continuous optical signal according to the radio frequency signal to obtain a plurality of modulated optical signals; an optical field division module, configured to perform superposition processing on all the modulated optical signals to obtain a frequency-sweeping optical field, divide the frequency-sweeping optical field to obtain a sensing light field and a reference light field, and input the sensing light of the sensing light field into the sensing optical fiber; a light field interference module, configured to receive a target sensing light field output by the sensing optical fiber, perform interference processing on the target sensing light field and the reference light field to obtain a beat frequency interference light intensity, and perform filtering processing on the beat frequency interference light intensity to obtain a target beat frequency interference signal; The sensing detection module is used to demodulate the target beat frequency interference signal to obtain a light field phase change, perform vibration positioning on the sensing optical fiber according to the light field phase change to obtain the optical fiber vibration position, and obtain a sensing detection result according to the optical fiber vibration position.

[0014] In addition, to achieve the above-mentioned purpose, the present invention also provides a terminal, wherein the terminal includes: a memory, a processor, and a forward transmission distributed optical fiber sensing detection program based on chirp modulation stored in the memory and runnable on the processor, wherein the forward transmission distributed optical fiber sensing detection program based on chirp modulation, when executed by the processor, implements the steps of the forward transmission distributed optical fiber sensing detection method based on chirp modulation as described above.

[0015] In addition, to achieve the above-mentioned purpose, the present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a forward transmission distributed optical fiber sensing detection program based on chirp modulation, and when the forward transmission distributed optical fiber sensing detection program based on chirp modulation is executed by a processor, the steps of the forward transmission distributed optical fiber sensing detection method based on chirp modulation as described above are implemented.

[0016] In the present invention, a sensing detection task of a sensing optical fiber is obtained, a single-frequency continuous optical signal and a radio frequency signal are obtained according to the sensing detection task, and the single-frequency continuous optical signal is chirped modulated according to the radio frequency signal to obtain multiple modulated optical signals; all the modulated optical signals are superimposed to obtain a swept light field, the swept light field is divided to obtain a sensing light field and a reference light field, and the sensing light of the sensing light field is input into the sensing optical fiber; the target sensing light field output by the sensing optical fiber is received, the target sensing light field is interfered with the reference light field to obtain a beat frequency interference light intensity, and the beat frequency interference light intensity is filtered to obtain a target beat frequency interference signal; the target beat frequency interference signal is demodulated to obtain a light field phase change, the sensing optical fiber is vibration-positioned according to the light field phase change, and the optical fiber vibration position is obtained, and the sensing detection result is obtained according to the optical fiber vibration position. The present invention not only reduces the detection cost, but also can accurately locate the vibration on the sensing optical fiber, timely detect intrusion events, thereby ensuring data transmission and data security on the sensing optical fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flow chart of a preferred embodiment of the forward transmission distributed optical fiber sensing detection method based on chirp modulation of the present invention; Figure 2 Schematic diagram of the overall process of the forward transmission distributed optical fiber sensing detection method based on chirp modulation of the present invention; Figure 3 Schematic diagram of the structure principle of an I / Q modulator in a preferred embodiment of the present invention; Figure 4 This is a schematic diagram of the vibration positioning process in a preferred embodiment of the present invention; Figure 5Schematic diagram of the power spectrum density of the sensing optical fiber signal at different frequencies and positions in a preferred embodiment of the present invention; Figure 6 1 is a structural diagram of a preferred embodiment of a forward transmission distributed optical fiber sensing detection system based on chirp modulation according to the present invention; Figure 7 It is a structural diagram of a preferred embodiment of the terminal of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clear and distinct, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), such directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0020] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0021] The forward transmission distributed optical fiber sensing detection method based on chirp modulation described in the preferred embodiment of the present invention is as follows: Figure 1 As shown, the forward transmission distributed optical fiber sensing detection method based on chirp modulation includes the following steps: Step S10 obtains a sensing detection task of the sensing optical fiber, obtains a single-frequency continuous optical signal and a radio frequency signal according to the sensing detection task, and chirps the single-frequency continuous optical signal according to the radio frequency signal to obtain multiple modulated optical signals.

[0022] Specifically, in an embodiment of the present invention, in order to solve the problems in the prior art of inaccurate detection results obtained by sensing the entire sensing optical fiber through optical wave signals, resulting in the inability to accurately locate vibrations on the entire sensing optical fiber, thereby failing to timely detect intrusion events, and the high cost of sensing detection, the present invention proposes a forward transmission distributed optical fiber sensing detection method based on chirp modulation, which is implemented through a distributed optical fiber sensing system with single-ended forward transmission based on chirp modulation. This system includes a near-end transmitting and receiving module and a far-end delay module. The corresponding system schematic diagram is shown as follows. Figure 2 As shown, specifically, the sensing detection task of the sensing optical fiber is obtained, and the LD (LaserDiode, narrow linewidth single-frequency laser) and AWG (Arbitrary Waveform Generator, arbitrary waveform generator) are started according to the sensing detection task, and a single-frequency continuous optical signal is emitted by the narrow linewidth single-frequency laser, and the arbitrary waveform generator generates a radio frequency signal, wherein the radio frequency signal includes two chirped sweep frequency signals, namely and ,in, is the first chirp sweep signal, is the second chirp sweep signal, is the phase change caused by external disturbance, is the starting frequency of the sweep, is the sweep time, The sweep speed is the first chirp sweep signal and the second chirp sweep signal have a sweep range of 250MHz-750MHz, and a sweep time of 10ms. Therefore, the corresponding sweep speeds are 50GHz / s.

[0023] Afterwards, the RF signal is input into an I / Q modulator, which is composed of two MZMs (Mach-Zehnder Modulators) and a 90° phase shifter; Figure 3As shown, after the RF signal is input into the I / Q modulator, the automatic bias controller uses the PID (Proportional, Integral, Differential) algorithm to adjust the DC bias voltage so that the I / Q modulator operates at the quadrature point. At this time, the two MZMs inside the I / Q modulator are respectively in the push-pull working state, that is, the phase modulation signals of the upper and lower arms differ by 180 degrees, thereby optimizing the linear response and minimizing the distortion, and the single-frequency continuous optical signal I / Q modulator. The single-frequency continuous optical signal is first split into two MZM sub-modules, the I-channel and the Q-channel. In the I-channel, the single-frequency continuous optical signal passes through the two branch modulation channels, I+ and I-, respectively, and is modulated with the positive and negative components of the radio frequency signal in opposite phases. That is, the single-frequency continuous optical signal and the first chirped swept-frequency signal are modulated in opposite phases through the first I-channel modulation channel to obtain a first I-channel modulated optical signal. The single-frequency continuous optical signal and the first chirped swept-frequency signal are modulated in opposite phases through the second I-channel modulation channel to obtain a second I-channel modulated optical signal. Similarly, in the Q-channel, the single-frequency continuous optical signal passes through the two branch modulation channels, Q+ and Q-, respectively, and is modulated with the positive and negative components of the radio frequency signal after 90° phase shift. That is, the single-frequency continuous optical signal and the second chirped swept-frequency signal are modulated through the first Q-channel modulation channel to obtain a first Q-channel modulated optical signal. The single-frequency continuous optical signal and the second chirped swept-frequency signal are modulated through the second Q-channel modulation channel to obtain a second Q-channel modulated optical signal.

[0024] Step S20: superimpose all the modulated optical signals to obtain a swept light field, divide the swept light field to obtain a sensing light field and a reference light field, and input the sensing light of the sensing light field into the sensing optical fiber.

[0025] Specifically, after obtaining multiple modulated optical signals, all of the modulated optical signals are coherently superimposed in an optical combiner to form a complex optical field (i.e., a swept optical field) with adjustable amplitude and phase, thereby achieving I / Q modulation of the input RF signal. The expression of the swept optical field is: ; in, is the swept light field, is an imaginary number, is the light frequency output by the light source, which is the initial light frequency that has not been modulated. is the sweep time, and are all Bayesian expansions; among them, , is the starting frequency of the sweep, For the sweep speed, the expression of the swept light field is expanded by the first-order Bayesian method and regrouped. The expression of the expanded swept light field is: + ; in, is the positive first-order expansion coefficient of Bayes, is the negative third-order expansion coefficient of Bayes; thus, the +1-order sideband and -3-order sideband are retained, and the carrier and other sidebands are suppressed. The -3rd-order sideband is significantly suppressed when the chirp sweep signal is used to modulate the optical frequency of the input single-frequency continuous optical signal, generating a single-sideband frequency sweep with suppressed carrier. The frequency sweep linearity of the generated chirped swept optical signal is basically the same as that of the chirped swept signal.

[0026] Afterwards, the swept light field is divided and processed by OC (Optical Fiber Coupler) 1 to obtain a sensing light field and a reference light field, and the sensing light of the sensing light field is input into the sensing optical fiber through Cir (Circulator) 1, and then enters the remote time delay module through Cir2; after the sensing light enters the remote time delay module, the sensing light is divided into two sensing lights by OC2, one sensing light passes through TDF (Time Delay Fiber) 1 of a first preset length (for example, 10 km), and the other passes through TDF2 of a second preset length (for example, 20 km). The two sensing lights are recoupled at OC3 and return to the sensing optical fiber again through Cir2 to obtain the target sensing light; then, the light field of the target sensing light (i.e., the target sensing light field) is subjected to beat frequency interference with the reference light field at OC4 through Cir1 to obtain the corresponding beat frequency interference light intensity, which is finally measured by BPD (Balance Photoelectric Transmitter). Detector, balanced photodetector detects, converts into corresponding electrical signals, and is collected by OSC (Oscilloscope) for subsequent digital signal processing. On the other hand, due to the isolation of Cir2, the Rayleigh backscattered light in TDF1 and TDF2 does not enter the sensing fiber through port 2 of Cir2. Therefore, the target sensing light field returned to the receiving end through Cir1 It contains three parts: Rayleigh backscattered light field , the first light field that experiences Path 1 (propagation path 1) and the second light field that experiences Path2 (propagation path 2) ,in, The propagation path of PathRBS is: Cir1->Sensing fiber (sensing fiber)->Cir1->OC4; The transmission path Path1 is: Cir1->Sensing fiber->Cir2->OC2->TDF1->OC3->Cir2->Sensing fiber->Cir1->OC4; The transmission path Path2 is: Cir1->Sensing fiber->Cir2->OC2->TDF2->OC3->Cir2->Sensing fiber->Cir1->OC4.

[0027] From the expression of the expanded swept-frequency light field, it can be seen that the +1-order single-sideband detection light field (i.e., swept-frequency light field) output by Cir1 can be expressed as: ; in, is the initial amplitude of the light field. In the embodiment of the present invention, due to the propagation through three propagation paths, this initial amplitude of the light field can be ignored. The Rayleigh backscattered light field, the first light field, and the second light field returning to the receiving end of the transmitting and receiving module are respectively expressed as: ; ; ; in, is the Rayleigh backscattered light field within the sweep time, is the first light field within the sweep time, is the second light field within the sweep time, is the propagation time of the sensing light in the sensing optical fiber for one round trip, , is the sensing fiber length, is the refractive index of the sensing fiber, is the speed of light in vacuum, is the propagation time of the sensing light in the first delay fiber (i.e., TDF1), , is the length of TDF1, The propagation time of the sensing light in the second time-delay fiber (TDF2) is , is the length of TDF2.

[0028] Step S30: receiving the target sensing light field output by the sensing optical fiber, performing interference processing on the target sensing light field and the reference light field to obtain beat frequency interference light intensity, and performing filtering processing on the beat frequency interference light intensity to obtain a target beat frequency interference signal.

[0029] Specifically, in an embodiment of the present invention, after receiving the target sensing light field output by the sensing optical fiber, it is necessary to perform interference processing on the target sensing light field and the reference light field. The specific process is to calculate the light intensity based on the Rayleigh backscattered light field and the reference light field to obtain the Rayleigh backscattered light intensity. The corresponding expression is: ; The light intensity is calculated based on the first light field and the reference light field to obtain a first light intensity, and the corresponding expression is: ; The light intensity is calculated based on the second light field and the reference light field to obtain the second light intensity, and the corresponding expression is: ; in, is the Rayleigh backscattered light intensity, is the light frequency output by the light source, is the starting frequency of the sweep, is the beat frequency of the Rayleigh backscattered beat frequency interference signal, is the phase change caused by external disturbance, is the first light intensity, is the carrier frequency of the first beat frequency interference signal, is the second light intensity; , , .

[0030] The Rayleigh backscattered light intensity, the first light intensity, and the second light intensity are superimposed to obtain the beat frequency interference light intensity, and the corresponding expression is: ; From the expressions of Rayleigh backscattering intensity and beat frequency interference intensity, we can know that as long as the length of TDF2 is set to be greater than TDF1, 、 and There will be a clear separation in the frequency domain. Afterwards, multiple bandpass filters with different frequencies are set, and the Rayleigh backscattered beat frequency interference signal, the first beat frequency interference signal, and the second beat frequency interference signal can be extracted respectively through the bandpass filters of all the bandpass filters, and the Rayleigh backscattered signal can be filtered out at the same time. At the far end, due to the characteristics of the circulator, the sensing light entering from port 3 can only exit from port 2, and the sensing light entering from port 2 can only exit from port 1. The backscattered light cannot enter the sensing optical fiber from port 2, so it is also filtered out, that is, the Rayleigh backscattered beat frequency interference signal is filtered out to obtain a processing result, and the first beat frequency interference signal and the second beat frequency interference signal are combined according to the processing result to obtain the target beat frequency interference signal.

[0031] Step S40: demodulate the target beat frequency interference signal to obtain a light field phase change, perform vibration positioning on the sensing optical fiber according to the light field phase change to obtain an optical fiber vibration position, and obtain a sensing detection result according to the optical fiber vibration position.

[0032] Specifically, since the target beat frequency interference signal has a carrier frequency and (i.e. the first beat frequency interference signal has a carrier frequency , and the second beat frequency interference signal has a carrier frequency ), therefore, in the embodiment of the present invention, if Figure 4 As shown, the Hilbert transform is used to generate I / Q components to perform I / Q demodulation on the target beat frequency interference signal. The specific demodulation process is as follows: assuming that the signal containing The signal (i.e., the first beat frequency interference signal) and the The corresponding expressions are: ; ; in, is the first beat frequency interference signal, is the amplitude of the first beat frequency interference signal, is the phase change of the first light field, is the second beat frequency interference signal, is the amplitude of the second beat frequency interference signal, is the phase change of the second light field; then, the corresponding analytical signal needs to be constructed. , that is, the first beat frequency interference signal is constructed to obtain the first analytical signal, and the corresponding expression is: ; use The expression for the first analytic signal multiplied by the conjugate complex term is: ; in, is the first analytical signal, is an imaginary expression, is the Hilbert transform result of the first beat frequency interference signal, is the amplitude of the first analytical signal, is the first analytical signal after transformation; and according to The first I component and the first Q component can be obtained, and the corresponding expressions are: ; ; in, is the first I component, i.e. the first in-direction component, for The real component of is the first Q component, that is, the first orthogonal component, for imaginary component; obtaining the first light field phase change according to the first I component and the first Q component , the corresponding expression is: .

[0033] for , that is, the second beat frequency interference signal is constructed to obtain the second analytical signal, and the corresponding expression is: ; use The expression for the second analytic signal multiplied by the conjugate complex term is: ; in, is the second analytical signal, is the Hilbert transform result of the second beat frequency interference signal, is the amplitude of the second analytical signal, is the second analytical signal after transformation; and according to the second I component and the second Q component, the corresponding expression is: ; ; in, is the second I component, i.e. the second in-direction component, for The real component of is the second Q component, that is, the second orthogonal component, for According to the second I component and the second Q component, the second light field phase change is obtained , the corresponding expression is: .

[0034] After that, it is necessary to perform vibration positioning according to the phase change of the light field, that is, to perform vibration positioning on the sensing optical fiber according to the phase change of the light field to obtain the optical fiber vibration position. The specific positioning process is as follows: and The phase change caused by external disturbance can be expressed as: ; ; in, is the time the sensing light travels in the first path, is the propagation time of the sensing light in the second path (i.e., the second path propagation time); the first path is PZT (Piezoelectric Transducer) -> Cir2 -> TDF1 -> Cir2 -> PZT, and the second path is PZT -> Cir2 -> TDF2 -> Cir2 -> PZT. In subsequent digital signal processing, the first light field phase change and the second light field phase change are reconstructed to obtain the first phase and the second phase. The corresponding expressions are: ; ; in, is the first phase, is the second phase, is the time difference, .

[0035] like Figure 4 As shown, the first phase is expanded, and the expanded first phase is: ; At the same time, the second phase is time-shifted, and the second phase after the shift It can be expressed as: ; Therefore, it can be concluded that , and and Cross-correlation can be obtained , the vibration position is detected according to the propagation time of the second path to obtain the optical fiber vibration position, which is expressed as: ; in, is the optical fiber vibration position, is the propagation time of the sensing light in the sensing optical fiber for one round trip, is the propagation time of the sensing light in the second delay fiber, is the refractive index of the sensing fiber, is the speed of light in a vacuum; and a sensing detection result is obtained according to the vibration position of the optical fiber, wherein the sensing detection result includes PSD (Power Spectral Density, power spectrum density) at different frequencies and PSD at different positions, wherein the PSD at different frequencies is as follows Figure 5 In part (a), the PSD at different positions is as follows Figure 5 Part (b) of Figure 5 Part (b) also shows that there is flange attenuation at the fiber connection.

[0036] The beneficial effects of the present invention are as follows: (1) by using chirped swept frequency light as the detection light, two delayed optical fibers of different lengths are set at the far end for frequency division, and a circulator is set as the input device at the far end, and the unidirectional input and output characteristics of the circulator are used to isolate the backscattered light, effectively preventing the backscattered light generated at the far end from entering the sensing optical fiber; (2) it is proposed to use an I / Q modulator for optical intensity modulation, and respectively input a chirped swept frequency optical signal with a phase difference of as the modulation signal, and perform carrier suppressed single sideband modulation, without the need to use an additional optical filter to filter out the carrier. Waves and redundant sidebands, and an automatic bias point controller is used to dynamically adjust the bias voltage so that the bias voltage is in an orthogonal position and stably outputs the single-sideband light intensity signal; (3) The near-end receiving module uses two bandpass filters to extract the forward light of the two paths and eliminate the Rayleigh backscattered signal, thereby improving the phase signal-to-noise ratio and increasing the sensing distance; (4) By using a single-core bidirectional structure, the cost of optical fiber laying is reduced; (5) Passive devices are used at the end of the optical fiber, so that the system can still operate effectively in remote areas and remote passive environments.

[0037] Furthermore, if Figure 6 As shown, based on the above-mentioned forward transmission distributed optical fiber sensing detection method based on chirp modulation, the present invention also provides a forward transmission distributed optical fiber sensing detection system based on chirp modulation, wherein the forward transmission distributed optical fiber sensing detection system based on chirp modulation includes: a signal modulation module 51 for acquiring a sensing detection task of a sensing optical fiber, acquiring a single-frequency continuous optical signal and a radio frequency signal according to the sensing detection task, and chirping-modulating the single-frequency continuous optical signal according to the radio frequency signal to obtain a plurality of modulated optical signals; an optical field division module 52 for superimposing all the modulated optical signals to obtain a swept-frequency optical field, dividing the swept-frequency optical field to obtain a sensing optical field and a reference optical field, and inputting the sensing light of the sensing optical field into the sensing optical fiber; The light field interference module 53 is used to receive the target sensing light field output by the sensing optical fiber, perform interference processing on the target sensing light field and the reference light field to obtain a beat frequency interference light intensity, and perform filtering processing on the beat frequency interference light intensity to obtain a target beat frequency interference signal; The sensing detection module 54 is used to demodulate the target beat frequency interference signal to obtain a light field phase change, perform vibration positioning on the sensing optical fiber according to the light field phase change to obtain an optical fiber vibration position, and obtain a sensing detection result according to the optical fiber vibration position.

[0038] Furthermore, if Figure 7 As shown, based on the above-mentioned forward transmission distributed optical fiber sensing detection method based on chirp modulation, the present invention also provides a terminal, which includes a processor 10, a memory 20 and a display 30. Figure 7 Only some of the components of the terminal are shown, but it should be understood that implementation of all of the shown components is not required, and more or fewer components may be implemented instead.

[0039] In some embodiments, the memory 20 may be an internal storage unit of the terminal, such as a hard drive or memory of the terminal. In other embodiments, the memory 20 may also be an external storage device of the terminal, such as a plug-in hard drive, a Smart Media Card (SMC), a Secure Digital (SD) card, a flash card, etc. equipped on the terminal. Furthermore, the memory 20 may include both the internal storage unit of the terminal and an external storage device. The memory 20 is used to store application software installed on the terminal and various types of data, such as program code of the installed terminal. The memory 20 may also be used to temporarily store data that has been output or is about to be output. In one embodiment, the memory 20 stores a forward transmission distributed optical fiber sensing detection program 40 based on chirp modulation. The forward transmission distributed optical fiber sensing detection program 40 based on chirp modulation can be executed by the processor 10, thereby implementing the forward transmission distributed optical fiber sensing detection method based on chirp modulation in the present application.

[0040] In some embodiments, the processor 10 may be a central processing unit (CPU), a microprocessor, or other data processing chip, configured to execute program code or process data stored in the memory 20, such as executing the chirp-modulated forward transmission distributed optical fiber sensing detection method.

[0041] In some embodiments, the display 30 may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, an OLED (Organic Light-Emitting Diode) touch screen, etc. The display 30 is used to display information on the terminal and to display a visual user interface.

[0042] In one embodiment, when the processor 10 executes the chirp modulation-based forward transmission distributed optical fiber sensing detection program 40 in the memory 20, the following steps are implemented: Acquiring a sensing detection task of a sensing optical fiber, acquiring a single-frequency continuous optical signal and a radio frequency signal according to the sensing detection task, and chirping modulating the single-frequency continuous optical signal according to the radio frequency signal to obtain a plurality of modulated optical signals; Superimposing all the modulated optical signals to obtain a frequency-sweeping optical field, dividing the frequency-sweeping optical field to obtain a sensing light field and a reference light field, and inputting the sensing light of the sensing light field into the sensing optical fiber; receiving a target sensing light field output by the sensing optical fiber, performing interference processing on the target sensing light field and the reference light field to obtain a beat frequency interference light intensity, and performing filtering processing on the beat frequency interference light intensity to obtain a target beat frequency interference signal; The target beat frequency interference signal is demodulated to obtain a light field phase change, the sensing optical fiber is vibration-positioned according to the light field phase change to obtain an optical fiber vibration position, and a sensing detection result is obtained according to the optical fiber vibration position.

[0043] The radio frequency signal includes a first chirped swept frequency signal and a second chirped swept frequency signal, and the modulated optical signal includes a first I-channel modulated optical signal, a second I-channel modulated optical signal, a first Q-channel modulated optical signal, and a second Q-channel modulated optical signal; The chirp-modulating the single-frequency continuous optical signal according to the radio frequency signal to obtain a plurality of modulated optical signals specifically includes: Performing phase-opposite modulation on the single-frequency continuous optical signal and the first chirped swept-frequency signal through a first I-channel modulation channel to obtain a first I-channel modulated optical signal; Performing phase-opposite modulation on the single-frequency continuous optical signal and the first chirped swept-frequency signal through a second I-channel modulation channel to obtain a second I-channel modulated optical signal; Modulating the single-frequency continuous optical signal and the second chirped swept-frequency signal through a first Q-channel modulation channel to obtain a first Q-channel modulated optical signal; The single-frequency continuous optical signal and the second chirped frequency-sweep signal are modulated through a second Q-path modulation channel to obtain a second Q-path modulated optical signal.

[0044] Wherein, the target sensing light field includes Rayleigh backscattered light field, the first light field and the second light field; The interfering process of the target sensing light field and the reference light field to obtain a beat frequency interference light intensity, and filtering the beat frequency interference light intensity to obtain a target beat frequency interference signal specifically includes: performing light intensity calculation based on the Rayleigh backscattered light field and the reference light field to obtain the Rayleigh backscattered light intensity; Performing light intensity calculation based on the first light field and the reference light field to obtain a first light intensity; Performing light intensity calculation based on the second light field and the reference light field to obtain a second light intensity; The Rayleigh backscattered light intensity, the first light intensity and the second light intensity are superimposed to obtain a beat frequency interference light intensity, and a plurality of bandpass filters with different frequencies are set; Performing signal extraction on the beat frequency interference light intensity according to the passbands of all the bandpass filters to obtain a Rayleigh backscattered beat frequency interference signal, a first beat frequency interference signal, and a second beat frequency interference signal; The Rayleigh backscattered beat frequency interference signal is filtered to obtain a processing result, and the first beat frequency interference signal and the second beat frequency interference signal are combined according to the processing result to obtain a target beat frequency interference signal.

[0045] The light intensity calculation is performed based on the Rayleigh backscattered light field and the reference light field, specifically: ; The light intensity calculation according to the first light field and the reference light field is specifically performed as follows: ; The light intensity calculation according to the second light field and the reference light field is specifically performed as follows: ; in, is the Rayleigh backscattered light intensity, is the propagation time of the sensing light in the sensing optical fiber for one round trip, is the sensing fiber length, is the propagation time, is the light frequency output by the light source, is the starting frequency of the sweep, is the beat frequency of the Rayleigh backscattered beat frequency interference signal, is the sweep time, is the sweep speed, is the phase change caused by external disturbance, is the first light intensity, is the propagation time of the sensing light in the first delay fiber, is the carrier frequency of the first beat frequency interference signal, is the second light intensity, is the propagation time of the sensing light in the second delay optical fiber.

[0046] Wherein, the light field phase change includes a first light field phase change and a second light field phase change; The demodulating the target beat frequency interference signal to obtain a light field phase change specifically includes: Performing signal construction on a first beat frequency interference signal of the target beat frequency interference signal to obtain a first analytical signal, and performing component calculation on the first analytical signal to obtain a first I component and a first Q component; Performing signal construction on a second beat frequency interference signal of the target beat frequency interference signal to obtain a second analytical signal, and performing component calculation on the second analytical signal to obtain a second I component and a second Q component; A first light field phase change is obtained according to the first I component and the first Q component, and a second light field phase change is obtained according to the second I component and the second Q component.

[0047] The signal construction of the first beat frequency interference signal of the target beat frequency interference signal is specifically as follows: ; The signal construction of the second beat frequency interference signal of the target beat frequency interference signal is specifically as follows: ; in, is the first analytical signal, is the first beat frequency interference signal, is an imaginary expression, is the Hilbert transform result of the first beat frequency interference signal, is the amplitude of the first analytical signal, is the carrier frequency of the first beat frequency interference signal, is the sweep time, is the phase change of the first light field, is the second analytical signal, is the second beat frequency interference signal, is the Hilbert transform result of the second beat frequency interference signal, is the amplitude of the second analytical signal, is the carrier frequency of the second beat frequency interference signal, is the phase change of the second light field.

[0048] The vibrating positioning of the sensing optical fiber according to the phase change of the light field to obtain the optical fiber vibration position, and obtaining the sensing detection result according to the optical fiber vibration position, specifically includes: performing phase reconstruction on the first light field phase change and the second light field phase change to obtain a first phase and a second phase, and performing cross-correlation processing on the first phase and the second phase to obtain a second path propagation time; Performing vibration position detection based on the second path propagation time to obtain the optical fiber vibration position, and obtaining a sensing detection result based on the optical fiber vibration position; The vibration position detection according to the second path propagation time is specifically performed as follows: ; in, is the optical fiber vibration position, is the propagation time of the sensing light in the sensing optical fiber for one round trip, Second path propagation time, is the propagation time of the sensing light in the second delay fiber, is the refractive index of the sensing fiber, is the speed of light in a vacuum.

[0049] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a forward transmission distributed optical fiber sensing detection program based on chirp modulation, and when the forward transmission distributed optical fiber sensing detection program based on chirp modulation is executed by a processor, the steps of the forward transmission distributed optical fiber sensing detection method based on chirp modulation as described above are implemented.

[0050] In summary, the present invention provides a forward transmission distributed optical fiber sensing detection method, system, terminal and storage medium based on chirp modulation. The method includes: obtaining a sensing detection task of a sensing optical fiber, obtaining a single-frequency continuous optical signal and a radio frequency signal according to the sensing detection task, and chirping the single-frequency continuous optical signal according to the radio frequency signal to obtain multiple modulated optical signals; superimposing all the modulated optical signals to obtain a swept light field, dividing the swept light field to obtain a sensing light field and a reference light field, and inputting the sensing light of the sensing light field into the sensing optical fiber; receiving a target sensing light field output by the sensing optical fiber, interfering the target sensing light field with the reference light field to obtain a beat interference light intensity, and filtering the beat interference light intensity to obtain a target beat interference signal; demodulating the target beat interference signal to obtain a light field phase change, performing vibration positioning on the sensing optical fiber according to the light field phase change to obtain a fiber vibration position, and obtaining a sensing detection result based on the fiber vibration position. The present invention not only reduces detection costs, but also can accurately locate vibrations on the sensing optical fiber and promptly detect intrusion events, thereby ensuring data transmission and data security on the sensing optical fiber.

[0051] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a..." does not preclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0052] Of course, those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing related hardware (such as a processor, controller, etc.) through a computer program. The program can be stored in a computer-readable storage medium that can be read by a computer. When executed, the program can include the processes in the above-described method embodiments. The computer-readable storage medium can be a memory, a magnetic disk, an optical disk, etc.

[0053] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A forward transmission distributed optical fiber sensing detection method based on chirp modulation, characterized in that: The forward transmission distributed optical fiber sensing detection method based on chirp modulation includes: Acquiring a sensing detection task of a sensing optical fiber, acquiring a single-frequency continuous optical signal and a radio frequency signal according to the sensing detection task, and chirping modulating the single-frequency continuous optical signal according to the radio frequency signal to obtain a plurality of modulated optical signals; Superimposing all the modulated optical signals to obtain a frequency-sweeping optical field, dividing the frequency-sweeping optical field to obtain a sensing light field and a reference light field, and inputting the sensing light of the sensing light field into the sensing optical fiber; receiving a target sensing light field output by the sensing optical fiber, performing interference processing on the target sensing light field and the reference light field to obtain a beat frequency interference light intensity, and performing filtering processing on the beat frequency interference light intensity to obtain a target beat frequency interference signal; The target beat frequency interference signal is demodulated to obtain a light field phase change, the sensing optical fiber is vibration-positioned according to the light field phase change to obtain an optical fiber vibration position, and a sensing detection result is obtained according to the optical fiber vibration position.

2. The forward transmission distributed optical fiber sensing detection method based on chirp modulation according to claim 1, characterized in that: The radio frequency signal includes a first chirped frequency-sweep signal and a second chirped frequency-sweep signal, and the modulated optical signal includes a first I-channel modulated optical signal, a second I-channel modulated optical signal, a first Q-channel modulated optical signal, and a second Q-channel modulated optical signal; The chirping modulation of the single-frequency continuous optical signal according to the radio frequency signal to obtain a plurality of modulated optical signals specifically includes: Performing phase-opposite modulation on the single-frequency continuous optical signal and the first chirped swept-frequency signal through a first I-channel modulation channel to obtain a first I-channel modulated optical signal; performing phase-opposite modulation on the single-frequency continuous optical signal and the first chirped swept-frequency signal through a second I-channel modulation channel to obtain a second I-channel modulated optical signal; Modulating the single-frequency continuous optical signal and the second chirped swept-frequency signal through a first Q-channel modulation channel to obtain a first Q-channel modulated optical signal; The single-frequency continuous optical signal and the second chirped frequency-sweep signal are modulated through a second Q-path modulation channel to obtain a second Q-path modulated optical signal.

3. The forward transmission distributed optical fiber sensing detection method based on chirp modulation according to claim 1, characterized in that: The target sensing light field includes a Rayleigh backscattered light field, a first light field, and a second light field; The interfering process of the target sensing light field and the reference light field to obtain a beat frequency interference light intensity, and filtering the beat frequency interference light intensity to obtain a target beat frequency interference signal specifically includes: performing light intensity calculation based on the Rayleigh backscattered light field and the reference light field to obtain the Rayleigh backscattered light intensity; Performing light intensity calculation based on the first light field and the reference light field to obtain a first light intensity; Performing light intensity calculation based on the second light field and the reference light field to obtain a second light intensity; The Rayleigh backscattered light intensity, the first light intensity and the second light intensity are superimposed to obtain a beat frequency interference light intensity, and a plurality of bandpass filters with different frequencies are set; Performing signal extraction on the beat frequency interference light intensity according to the passbands of all the bandpass filters to obtain a Rayleigh backscattered beat frequency interference signal, a first beat frequency interference signal, and a second beat frequency interference signal; The Rayleigh backscattered beat frequency interference signal is filtered to obtain a processing result, and the first beat frequency interference signal and the second beat frequency interference signal are combined according to the processing result to obtain a target beat frequency interference signal.

4. The forward transmission distributed optical fiber sensing detection method based on chirp modulation according to claim 3, characterized in that: The light intensity calculation is performed according to the Rayleigh backscattered light field and the reference light field, specifically: ； The light intensity calculation according to the first light field and the reference light field is specifically performed as follows: ； The light intensity calculation according to the second light field and the reference light field is specifically performed as follows: ； in, is the Rayleigh backscattered light intensity, is the propagation time of the sensing light in the sensing optical fiber for one round trip, is the sensing fiber length, is the propagation time, is the light frequency output by the light source, is the starting frequency of the sweep, is the beat frequency of the Rayleigh backscattered beat frequency interference signal, is the sweep time, is the sweep speed, is the phase change caused by external disturbance, is the first light intensity, is the propagation time of the sensing light in the first delay fiber, is the carrier frequency of the first beat frequency interference signal, is the second light intensity, is the propagation time of the sensing light in the second delay optical fiber.

5. The forward transmission distributed optical fiber sensing detection method based on chirp modulation according to claim 1, characterized in that: The light field phase change includes a first light field phase change and a second light field phase change; The demodulating the target beat frequency interference signal to obtain a light field phase change specifically includes: Performing signal construction on a first beat frequency interference signal of the target beat frequency interference signal to obtain a first analytical signal, and performing component calculation on the first analytical signal to obtain a first I component and a first Q component; Performing signal construction on a second beat frequency interference signal of the target beat frequency interference signal to obtain a second analytical signal, and performing component calculation on the second analytical signal to obtain a second I component and a second Q component; A first light field phase change is obtained according to the first I component and the first Q component, and a second light field phase change is obtained according to the second I component and the second Q component.

6. The forward transmission distributed optical fiber sensing detection method based on chirp modulation according to claim 5, characterized in that: The signal construction of the first beat frequency interference signal of the target beat frequency interference signal is specifically as follows: ； The signal construction of the second beat frequency interference signal of the target beat frequency interference signal is specifically as follows: ； in, is the first analytical signal, is the first beat frequency interference signal, is an imaginary expression, is the Hilbert transform result of the first beat frequency interference signal, is the amplitude of the first analytical signal, is the carrier frequency of the first beat frequency interference signal, is the sweep time, is the phase change of the first light field, is the second analytical signal, is the second beat frequency interference signal, is the Hilbert transform result of the second beat frequency interference signal, is the amplitude of the second analytical signal, is the carrier frequency of the second beat frequency interference signal, is the phase change of the second light field.

7. The forward transmission distributed optical fiber sensing detection method based on chirp modulation according to claim 5, characterized in that: The vibrating positioning of the sensing optical fiber according to the phase change of the light field to obtain the optical fiber vibration position, and obtaining the sensing detection result according to the optical fiber vibration position, specifically includes: performing phase reconstruction on the first light field phase change and the second light field phase change to obtain a first phase and a second phase, and performing cross-correlation processing on the first phase and the second phase to obtain a second path propagation time; Performing vibration position detection based on the second path propagation time to obtain the optical fiber vibration position, and obtaining a sensing detection result based on the optical fiber vibration position; The vibration position detection according to the second path propagation time is specifically performed as follows: ； in, is the optical fiber vibration position, is the propagation time of the sensing light in the sensing optical fiber for one round trip, Second path propagation time, is the propagation time of the sensing light in the second delay fiber, is the refractive index of the sensing fiber, is the speed of light in a vacuum.

8. A forward transmission distributed optical fiber sensing detection system based on chirp modulation, characterized in that: The forward transmission distributed optical fiber sensing detection system based on chirp modulation includes: a signal modulation module, configured to obtain a sensing detection task of the sensing optical fiber, obtain a single-frequency continuous optical signal and a radio frequency signal according to the sensing detection task, and chirp-modulate the single-frequency continuous optical signal according to the radio frequency signal to obtain a plurality of modulated optical signals; an optical field division module, configured to perform superposition processing on all the modulated optical signals to obtain a frequency-sweeping optical field, divide the frequency-sweeping optical field to obtain a sensing light field and a reference light field, and input the sensing light of the sensing light field into the sensing optical fiber; a light field interference module, configured to receive a target sensing light field output by the sensing optical fiber, perform interference processing on the target sensing light field and the reference light field to obtain a beat frequency interference light intensity, and perform filtering processing on the beat frequency interference light intensity to obtain a target beat frequency interference signal; The sensing detection module is used to demodulate the target beat frequency interference signal to obtain a light field phase change, perform vibration positioning on the sensing optical fiber according to the light field phase change to obtain the optical fiber vibration position, and obtain a sensing detection result according to the optical fiber vibration position.

9. A terminal, characterized in that: The terminal includes a memory, a processor, and a program stored in the memory and executable on the processor. When the program is executed by the processor, the steps of the forward transmission distributed optical fiber sensing detection method based on chirp modulation are implemented as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that A computer program is stored thereon, and the computer-readable storage medium stores a forward transmission distributed optical fiber sensing detection program based on chirp modulation. When the forward transmission distributed optical fiber sensing detection program based on chirp modulation is executed by a processor, the steps of the forward transmission distributed optical fiber sensing detection method based on chirp modulation as described in any one of claims 1 to 7 are implemented.

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