Method and system for automatically adjusting sampling time delay of time division multiplexing optical fiber hydrophone array

Abstract

The invention relates to the technical field of time division multiplexing optical fiber hydrophones, in particular to a time division multiplexing optical fiber hydrophone array sampling time delay automatic adjustment method and system. The method for automatically adjusting the sampling time delay of the time division multiplexing optical fiber hydrophone array comprises the following steps: S1, acquiring an optical signal output by the time division multiplexing optical fiber hydrophone array; s2, based on the sliding window technology and the optical signals, target sampling time delay is determined, and the target sampling time delay is the difference value between the moment when the time division multiplexing optical fiber hydrophone array receives the optical pulses and the moment when the time division multiplexing optical fiber hydrophone array samples the output optical signals; s3, determining an error ratio corresponding to the target sampling time delay according to the target sampling time delay and the optical signal; and S4, under the condition that the error ratio is greater than a preset value, adjusting the target sampling time delay based on the sliding window technology and the optical signal. Automatic correction and adjustment of the target sampling time delay are achieved, manual calibration is not needed, the accuracy of the target sampling time delay is improved, and the automation level of the system is improved.

Description

Technical Field

[0001] The present application relates to the technical field of time-division multiplexed optical fiber hydrophones, and in particular to a method and system for automatically adjusting sampling delay of a time-division multiplexed optical fiber hydrophone array. Background Art

[0002] Fiber-optic hydrophone is a means of underwater acoustic detection based on fiber-optic sensing technology. In practical applications, multiple hydrophones are usually combined into an array to obtain array processing gain to improve detection performance. In recent years, the demand for ocean underwater acoustic detection has grown rapidly, and the scale of fiber-optic hydrophone arrays has also been increasing. Time-division multiplexing technology based on pulse light emission and reception is a commonly used technology for increasing the array scale of fiber-optic hydrophone array systems. Multiple hydrophone probes reuse the same optical fiber for optical pulse signal transmission. The system ensures that multiple optical pulses do not overlap in the time domain through precisely set delays. This solution has the advantages of a small number of optical fiber cores and low cost of optoelectronic modulation and demodulation systems. At the same time, the receiver of the fiber-optic hydrophone needs to accurately sample and delay the multiple time-division multiplexed pulse light signals in the same optical fiber, so as to achieve accurate and reliable demultiplexing.

[0003] The existing fiber optic hydrophone time division array system is generally deployed in shore-based fixed arrays or ship-borne towed arrays. The sampling delay of the time-division multiplexed pulse optical signal is usually manually calibrated before leaving the factory, or manually modified during equipment inspection. During system operation, the sampling delay is generally defaulted to a fixed value that does not need to be adjusted. However, as more and more underwater unmanned detection platforms are equipped with fiber optic hydrophone arrays for deep-sea acoustic detection, the parameters of the fiber optic hydrophone array may change with environmental changes such as water depth, hydrostatic pressure, and temperature. The method of manually calibrating the sampling delay of the time-division multiplexed channel can no longer meet the requirements of long-term intelligent and autonomous operation of unmanned platforms.

[0004] Therefore, a delay adjustment method is urgently needed to solve the above problems. Summary of the invention

[0005] The embodiments of the present application provide a method and system for automatically adjusting the sampling delay of a time-division multiplexed fiber optic hydrophone array to achieve automatic correction and adjustment of the target sampling delay without manual calibration, thereby improving the accuracy of the target sampling delay and enhancing the automation level of the system.

[0006] In some embodiments, a method for automatically adjusting the sampling delay of a time-division multiplexed fiber optic hydrophone array is provided, comprising: S1: acquiring an optical signal output by the time-division multiplexed fiber optic hydrophone array; S2: determining a target sampling delay based on a sliding window technique and the optical signal, wherein the target sampling delay is the difference between the moment when the time-division multiplexed fiber optic hydrophone array receives an optical pulse and the moment when the output optical signal is sampled; S3: determining an error ratio corresponding to the target sampling delay based on the target sampling delay and the optical signal; S4: when the error ratio is greater than a preset value, adjusting the target sampling delay based on the sliding window technique and the optical signal.

[0007] By using the automatic adjustment method for sampling delay of a time-division multiplexed optical fiber hydrophone array provided in the embodiment of the present application, the target sampling delay can be determined according to the optical signal output by the time-division multiplexed optical fiber hydrophone array. If many errors occur when sampling using the target sampling delay, the target sampling delay can be automatically adjusted according to the optical signal output by the time-division multiplexed optical fiber hydrophone array, thereby realizing automatic adjustment of the target sampling delay. The sampling delay of the time-division channel can be measured in real time and accurately during the operation of the time-division multiplexed optical fiber hydrophone array, and automatic correction can be performed to ensure the long-term stable operation of the automatic adjustment system for sampling delay of the time-division multiplexed optical fiber hydrophone array. Not only can the measurement and automatic control of time-division pulse sampling delay be realized without human intervention, but also the autonomous working ability of the automatic adjustment system for sampling delay of the time-division multiplexed optical fiber hydrophone array for different array states can be improved, thereby improving the automation level of the system.

[0008] Optionally, the optical signal includes an optical signal sequence composed of multiple optical signal points; based on the sliding window technology and the optical signal, the target sampling delay is determined, including: based on sliding window detection, a first target window is determined; the first target window is a sliding window in which the light intensity information of all optical signal points within the window satisfies a first condition; and the starting position of the first target window is used as the target sampling delay.

[0009] Optionally, the light intensity information includes the light intensity average value and variance of all light signal points in the sliding window, and the first condition is that the light intensity average value is less than the first light intensity average value and the variance is less than the first variance.

[0010] Optionally, based on sliding window detection, determining the first target window includes: sliding the sliding window from the initial position of the optical signal sequence across the optical signal sequence, and determining the light intensity information of all optical signal points in the window corresponding to the sliding window; the length of the sliding window is a preset length, and the preset length is less than the total number of optical signal points in the optical signal sequence; the step value of the sliding window is a preset step value; when the light intensity information satisfies the first condition, stopping sliding the sliding window and determining the sliding window as the first target window.

[0011] Optionally, after sliding the sliding window from the initial position of the optical signal sequence to pass through the optical signal sequence and determining the light intensity information of all optical signal points in the window corresponding to the sliding window, it also includes: when the light intensity information does not meet the first condition, determining whether the sliding window includes the last optical signal point of the optical signal sequence; when the sliding window includes the last optical signal point of the optical signal sequence, jumping to step S1; when the sliding window does not include the last optical signal point of the optical signal sequence, sliding the sliding window according to a preset step value, and calculating the light intensity information of all optical signal points in the window of the sliding window.

[0012] Optionally, according to the target sampling delay and the optical signal, the error ratio corresponding to the target sampling delay is determined, including: S31: taking the rising edge of the first pulse in the optical signal as the starting point, collecting a sub-signal interval of a preset length in the optical signal after the target sampling delay, and recording a detection record; S32: calculating the light intensity information in the sub-signal interval; S33: when the light intensity information does not meet the first condition, recording an error record; S34: calculating the error ratio of the first number to the second number, the first number is the number of error records, and the second number is the number of detection records.

[0013] Optionally, when the error ratio is greater than a preset value, the target sampling delay is determined based on the sliding window technology and the optical signal, including: starting from the first target window, the sliding window continues to slide across the optical signal sequence, and the light intensity information of all optical signal points in the window corresponding to the sliding window is determined; when the light intensity information meets the first condition, the sliding window is stopped, and the sliding window is determined to be the second target window; and the starting position of the second target window is determined as the target sampling delay.

[0014] Optionally, after determining the error ratio corresponding to the target sampling delay based on the target sampling delay and the optical signal, the method further includes: when the error ratio is less than or equal to a preset value, taking the rising edge of the second pulse in the optical signal as the starting point, collecting a sub-signal interval of a preset length in the optical signal after the target sampling delay, recording a detection record once, and jumping to step S32.

[0015] Optionally, when the error ratio is greater than a preset value, after adjusting the target sampling delay based on the sliding window technology and the optical signal, the method further includes: jumping to step S3.

[0016] In some embodiments, a time-division multiplexed fiber optic hydrophone array sampling delay automatic adjustment system is provided, comprising: a laser module, configured to output a laser signal to the time-division multiplexed fiber optic hydrophone array according to the basic working parameters of the time-division multiplexed fiber optic hydrophone array; the time-division multiplexed fiber optic hydrophone array, configured to receive the output laser signal and output an optical signal; a delay detection module, configured to S1: obtain the optical signal output by the time-division multiplexed fiber optic hydrophone array; S2: determine a target sampling delay based on a sliding window technique and an optical signal, the target sampling delay being the difference between the moment when the time-division multiplexed fiber optic hydrophone array receives an optical pulse and the moment when the output optical signal is sampled; S3: determine an error ratio corresponding to the target sampling delay based on the target sampling delay and the optical signal; S4: when the error ratio is greater than a preset value, adjust the target sampling delay based on the sliding window technique and the optical signal.

[0017] It can be understood that the beneficial effects that can be achieved by the technical solution provided by the above-mentioned time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment system can be referred to the beneficial effects of the time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment method and any of its optional implementations, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0019] Figure 1 A first structural block diagram of the time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment system provided in an embodiment of the present application; Figure 2 A second structural block diagram of the time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment system provided in an embodiment of the present application; Figure 3 A structural block diagram of a delay detection module provided in an embodiment of the present application; Figure 4 A first flow chart of a method for automatically adjusting sampling delay of a time-division multiplexed optical fiber hydrophone array provided in an embodiment of the present application; Figure 5 A schematic diagram of a pulse signal and an optical signal provided in an embodiment of the present application; Figure 6 A schematic diagram of sliding window detection provided in an embodiment of the present application; Figure 7 This is a second flow chart of the method for automatically adjusting the sampling delay of a time-division multiplexed optical fiber hydrophone array provided in an embodiment of the present application. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments of the present application, other embodiments obtained by ordinary technicians in this field without making creative work all belong to the protection scope of the present application.

[0021] In the following, the terms "first", "second", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0022] In addition, in the present application, directional terms such as "upper", "lower", "inner" and "outer" are defined relative to the orientation of the components schematically placed in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative description and clarification, and they can change accordingly according to the changes in the orientation of the components placed in the drawings.

[0023] To facilitate understanding of the technical solution of the application, some concepts involved in the application are first explained below.

[0024] Fiber optic hydrophone: An acoustic sensor based on fiber optic technology used to detect underwater sound wave signals. It uses the sensitivity of optical fiber to sound waves and converts the vibration signal of sound waves into a measurable light signal through the principle of light interference or reflection. Fiber optic hydrophones are widely used in ocean detection, military sonar systems, marine environment monitoring and underwater communications.

[0025] Time Division Multiplexing Fiber Optic Hydrophone Array: A system that uses fiber optic technology and time division multiplexing (TDM) technology to achieve underwater acoustic detection. Time division multiplexing technology allows multiple hydrophones to share the same optical fiber for signal transmission, improving the efficiency and data transmission capacity of the system. The method of forming an array of multiple fiber optic hydrophones is realized to obtain array processing gain to improve detection performance.

[0026] In order to facilitate the understanding of the technical solution of the application, the relevant technologies involved in this application are first explained below.

[0027] In recent years, the demand for ocean acoustic detection has grown rapidly, and the scale of fiber-optic hydrophone arrays has also been increasing. Time-division multiplexing technology based on pulsed light emission and reception is a technology commonly used to increase the scale of fiber-optic hydrophone array systems. Multiple hydrophone probes reuse the same optical fiber for optical pulse signal transmission. The system ensures that multiple optical pulses do not overlap in the time domain through precisely set delays. This solution has the advantages of a small number of optical fiber cores and low cost of optoelectronic modulation and demodulation systems. At the same time, the receiver of the fiber-optic hydrophone needs to perform precise sampling delay control on the multiple time-division multiplexed pulse optical signals in the same optical fiber, thereby achieving accurate and reliable demultiplexing.

[0028] The existing fiber optic hydrophone time division array system is generally deployed in shore-based fixed arrays or ship-borne towed arrays. The sampling delay of the time-division multiplexed pulse optical signal is usually manually calibrated before leaving the factory, or manually modified during equipment inspection. During system operation, the sampling delay is generally defaulted to a fixed value that does not need to be adjusted. However, as more and more underwater unmanned detection platforms are equipped with fiber optic hydrophone arrays for deep-sea acoustic detection, the parameters of the fiber optic hydrophone array may change with environmental changes such as water depth, hydrostatic pressure, and temperature. The method of manually calibrating the sampling delay of the time-division multiplexed channel can no longer meet the requirements of long-term intelligent and autonomous operation of unmanned platforms.

[0029] Therefore, a method for automatically adjusting the sampling delay is needed to measure the sampling delay of the time-division channel in real time and accurately during the operation of the fiber optic hydrophone array, and to perform automatic correction to ensure the long-term stable operation of the time-division multiplexing system.

[0030] In view of the deficiencies in the prior art, the embodiments of the present application provide a method and system for automatically adjusting the sampling delay of a time-division multiplexed fiber optic hydrophone array, which can not only realize the time-division pulse sampling delay measurement and automatic control without human intervention, but also improve the autonomous working ability of the time-division multiplexed fiber optic hydrophone array sampling delay automatic adjustment system for different array states, thereby improving the automation level of the system.

[0031] Figure 1 This is a first structural block diagram of the automatic adjustment system for sampling delay of a time-division multiplexed optical fiber hydrophone array provided in an embodiment of the present application.

[0032] Combination Figure 1As shown, an embodiment of the present application provides a time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment system, comprising: a laser module 1, a time-division multiplexed optical fiber hydrophone array 2, and a delay detection module 3. The laser module 1 is configured to output a laser signal to the time-division multiplexed optical fiber hydrophone array 2 according to the basic working parameters of the time-division multiplexed optical fiber hydrophone array 2. The time-division multiplexed optical fiber hydrophone array 2 is configured to receive the output laser signal and output an optical signal. The delay detection module 3 is configured to receive the optical signal output by the time-division multiplexed optical fiber hydrophone array 2, and adjust the target sampling delay in real time according to the optical signal.

[0033] The time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment system provided in the embodiment of the present application can automatically adjust the target sampling delay in real time according to the optical signal output by the time-division multiplexed optical fiber hydrophone array 2, so as to accurately measure the sampling delay of the time-division channel in real time during the operation of the time-division multiplexed optical fiber hydrophone array 2, and automatically correct it, so as to ensure the long-term stable operation of the time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment system. Not only can the time-division pulse sampling delay measurement and automatic control be realized without human intervention, but also the autonomous working ability of the time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment system for different array states can be improved, thereby improving the automation level of the system.

[0034] Figure 2 This is a second structural block diagram of the time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment system provided in an embodiment of the present application.

[0035] Optionally, combined Figure 2 As shown, the time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment system also includes: a time-division pulse generation module 4, a pulse light modulation module 5, an optoelectronic conversion module 6 and a signal acquisition module 7. The time-division pulse generation module 4 is configured to output a pulse electrical signal to the pulse light modulation module 5 and the delay detection module 3 according to the preset period and preset pulse width of the time-division multiplexed optical fiber hydrophone array 2. The pulse light modulation module 5 receives the laser signal output by the laser module 1, and the pulse light modulation module 5 is configured to modulate the continuous light generated by the laser module 1 into a pulse light with a preset period and a preset pulse width according to the pulse electrical signal. Among them, the pulse light modulation module 5 turns on the light output when the pulse electrical signal is at a high level, and turns off the light output when the pulse electrical signal is at a low level. The optoelectronic conversion module 6 receives the output optical signal of the time-division multiplexed optical fiber hydrophone array 2, and the optoelectronic conversion module 6 is configured to convert the optical signal into an electrical signal, and output the electrical signal to the signal acquisition module 7. The signal acquisition module 7 is configured to collect a digital signal corresponding to the electrical signal, and output the digital signal to the delay detection module 3.

[0036] Specifically, the signal acquisition module 7 acquires and digitizes the analog electrical signal through an analog-to-digital converter (ADC) chip. Exemplarily, the signal acquisition module 7 continuously samples the return interference light signal of the time division multiplexing array starting at any pulse rising edge, where the sampling time length is , set in the embodiment of this application is two consecutive pulse repetition periods, that is , the ADC sampling rate is , the number of points obtained by sampling .

[0037] Figure 3 This is a structural block diagram of the delay detection module provided in an embodiment of the present application.

[0038] Optionally, combined Figure 3 As shown, the delay detection module 3 includes: an ADC data interface module 30, a time-division pulse interface module 31, an ADC data flow control module 32, an ADC data cache module 33, a sliding window data acquisition module 34, a first mean and variance calculation module 35, a sampling delay judgment module 36, a time-division demultiplexing module 37, a second mean and variance calculation module 38 and a sampling delay monitoring module 39.

[0039] The ADC data interface module 30 is configured to receive the digital signal output by the signal acquisition module 7 and transmit the digital signal to the ADC data flow control module 32 .

[0040] The time-division pulse interface module 31 is configured to receive the pulse electrical signal output by the time-division pulse generation module 4 , and transmit the pulse electrical signal to the ADC data flow control module 32 .

[0041] The ADC data flow control module 32 is configured to control the transmission direction of the ADC data flow according to an algorithm logic.

[0042] The ADC data buffer module 33 is configured to buffer the optical signals of two consecutive pulse repetition periods output by the time-division multiplexed optical fiber hydrophone array 2 . The optical signals are written by the ADC data flow control module 32 and read by the sliding window acquisition module 34 .

[0043] The sliding window data acquisition module 34 is configured to read optical signal data of a preset length from the ADC data buffer module 33, and output it to the first mean and variance calculation module 35. The preset length is determined by the size of the sliding window.

[0044] The first mean and variance calculation module 35 and the second mean and variance calculation module 38 are both configured to receive the optical signal data and calculate the mean and variance of the optical signal data.

[0045] The sampling delay judgment module 36 is configured to judge whether the current sliding window position is the first target window based on the mean and variance output by the first mean and variance calculation module 35. If it is the first target window, the sampling delay judgment result will be output to the ADC data flow control module 32, and the sliding window data acquisition module 34 will be notified to stop sliding the window. If it is not the first target window, the sliding window data acquisition module 34 will be notified to continue sliding the window.

[0046] The second mean and variance calculation module 38 is configured to receive the optical signal data output by the ADC data flow control module 32 , calculate the mean and variance of the optical signal data, and output them to the sampling delay monitoring module 39 .

[0047] The sampling delay monitoring module 39 determines whether there is a problem with the current sampling delay according to the mean and variance output by the second mean and variance calculation module 38 , and returns the determination result to the ADC data flow control module 32 .

[0048] The time division demultiplexing module 37 is configured to demodulate the optical signal output by the time division multiplexed optical fiber hydrophone array 2 according to the target sampling delay.

[0049] Specifically, the delay detection module 3 is a field programmable gate array (FPGA), the ADC data cache module 33 is implemented by a dual-port RAM resource in the FPGA, is written by the ADC data flow control module 32, and is read by the sliding window data acquisition module 34.

[0050] Specifically, after the algorithm initialization is completed, the module first enters the first working mode, and after detecting the rising edge of the first time-division multiplexing pulse of the optical signal obtained by the time-division pulse interface module 31, the module takes the rising edge as the starting point, continuously writes the ADC data stream with a length of two consecutive pulse repetition periods to the ADC data buffer module 33, and then waits for the output of the sampling delay judgment module 36. After waiting for the sampling delay judgment result output by the sampling delay judgment module 36, the ADC data flow control module 32 enters the second working mode, and takes each time-division multiplexing pulse rising edge as the starting point. After the target sampling delay clock cycle is delayed, the data stream corresponding to the preset length of the sliding window is output to the second mean and variance calculation module 38, and the subsequent ADC data stream is output to the demultiplexing module 37. In the second working mode, the ADC data flow control module 32 will stay in the mode by default and work cyclically. If the delay error indication signal output by the sampling delay monitoring module 39 is received (output when the error ratio corresponding to the target sampling delay is greater than the preset value), the first working mode will be entered again from the second working mode.

[0051] Figure 4This is the first flow chart of the method for automatically adjusting the sampling delay of a time-division multiplexed optical fiber hydrophone array provided in an embodiment of the present application.

[0052] Combination Figures 1 to 3 The time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment system and delay detection module shown, the embodiment of the present application also provides a time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment method, the execution body of the method can be a delay detection module, including steps S1 to S4, which are as follows: Step S1, obtaining an optical signal output by a time-division multiplexed optical fiber hydrophone array.

[0053] In this step, the optical signal has two consecutive pulse repetition periods and is buffered in the ADC data buffer module 33 .

[0054] Figure 5 Schematic diagram of pulse signal and optical signal provided in the embodiment of the present application. Specifically, Figure 5 (a) is the optical pulse signal input to the time-division multiplexed fiber optic hydrophone array (above the time axis t). Figure 5 (b) is the optical signal output by the time-division multiplexed fiber optic hydrophone array (below the time axis t), and the output optical signal includes a complete preset cycle and other partial preset cycles.

[0055] Combination Figure 5 As shown, when the optical pulse signal is input into the time-division multiplexing optical fiber hydrophone array, the target sampling delay D w After that, the time-division multiplexing optical fiber hydrophone array outputs the corresponding optical signal, and the optical signal is the optical signal segment corresponding to each of the multiple time-division multiplexing channels. Exemplarily, when the time-division multiplexing optical fiber hydrophone array includes K time-division multiplexing channels, combined with Figure 5 As shown in (b), the optical signal includes the optical signal segments output by each time division channel ( Figure 5 (b) schematically shows the first time division channel Q1, the second time division channel Q2 and the Kth time division channel Q K corresponding optical signal segment).

[0056] Specifically, the time-division multiplexing optical fiber hydrophone array sampling delay automatic adjustment system provided in the embodiment of the present application is for a time-division system using phase-generated carrier modulation, the number of time-division multiplexing channels is K, and the modulation frequency of the phase-generated carrier modulation is ,like Figure 5 As shown, after the fiber optic hydrophone array transmits the modulated optical pulse signal, the return light of the time division multiplexing array is composed of the superposition of pulse lights of multiple time division array elements. The sampling delay refers to the time difference between the pulse emission moment and the return moment of the first time division channel pulse.

[0057] Specifically, combined Figure 5 As shown in (a), the pulse width of the pulse signal is the preset pulse width. , the pulse period is the preset period .in, , . The time delay between each primitive is calculated based on the time division multiplexing array. The fiber delay line length between the elements Determined, exemplarily, ,in is the speed of light in the optical fiber.

[0058] Step S2, based on the sliding window technology and the optical signal, determine the target sampling delay, the target sampling delay being the difference between the time when the time division multiplexing optical fiber hydrophone array receives the optical pulse and the time when the output optical signal is sampled.

[0059] In this step, the initial target sampling delay is determined by using the sliding window technique and the optical signal.

[0060] Combination Figure 5 As shown, Figure 5 Middle D w This is the target sampling delay.

[0061] Optionally, the optical signal includes an optical signal sequence composed of a plurality of optical signal points; step S2 includes step S21 and step S22, which are specifically as follows: Step S21, based on sliding window detection, determine a first target window; the first target window is a sliding window in which light intensity information of all optical signal points meets a first condition.

[0062] In this step, satisfying the first condition can indicate that the window of the sliding window is a lightless area M (such as Figure 5 As shown in (b) in the figure, it shows that the starting position of the sliding window can correspond to the target sampling delay.

[0063] Optionally, the light intensity information includes the light intensity average value and variance of all light signal points in the sliding window, and the first condition is that the light intensity average value is less than the first light intensity average value and the variance is less than the first variance.

[0064] In this embodiment, the first condition is defined so that the area within the sliding window that meets the first condition is defined as a light-free area.

[0065] Exemplarily, the first light intensity average value is , the first variance is .in, is the maximum light intensity of all light signal points within the sliding window, It is the minimum light intensity of all optical signal points within the sliding window.

[0066] Optionally, step S21 includes step S211 and step S212, which are specifically as follows: Step S211, sliding the sliding window across the optical signal sequence from the initial position of the optical signal sequence, and determining the light intensity information of all optical signal points in the window corresponding to the sliding window; the length of the sliding window is a preset length, and the preset length is less than the total number of optical signal points in the optical signal sequence; the step value of the sliding window is the preset step value.

[0067] For example, the preset length , the default step value is 1.

[0068] Step S212: when the light intensity information satisfies the first condition, stop sliding the sliding window and determine that the sliding window is the first target window.

[0069] In this embodiment, by means of sliding window detection, the first sliding window that satisfies the first condition is detected in the optical signal sequence, and the first light-free zone is obtained, and the starting position of the sliding window corresponding to the light-free zone is the initial target sampling delay, thereby achieving the determined initial target sampling delay.

[0070] Figure 6 A schematic diagram of sliding window detection provided in an embodiment of the present application.

[0071] Exemplarily, the sliding window preset length The corresponding number of optical signal points is L, the preset step value of the sliding window is 1, and the optical signal sequence contains a total of N optical signal points. Figure 6 As shown, Figure 6 In (a), the sliding window is located at the initial position of the optical signal sequence. The initial position is that the sliding window includes the first optical signal point to the Lth optical signal point in the optical signal sequence. Figure 6 The starting position of the sliding window 101 in (a) is A1 and the ending position is B1. Figure 6 In (b), the sliding window includes the second optical signal point to the L+1th optical signal point after the sliding window moves once according to the preset step value. Figure 6 The starting position of the sliding window 102 in (b) is A2 and the ending position is B2. Figure 6 (c) is the case where the sliding window moves to the last position of the optical signal sequence. The sliding window contains the NLth optical signal point to the Nth optical signal point. Figure 6 The starting position of the sliding window 103 in (c) is A3 and the ending position is B3.

[0072] Optionally, after step S211, steps S213 to S215 are further included, which are specifically as follows: Step S213: when the light intensity information does not satisfy the first condition, determining whether the sliding window includes the last light signal point of the light signal sequence.

[0073] Step S214: when the sliding window includes the last optical signal point of the optical signal sequence, jump to step S1.

[0074] Step S215: When the sliding window does not include the last optical signal point of the optical signal sequence, the sliding window is slid according to a preset step value, and the light intensity information of all optical signal points within the sliding window is calculated.

[0075] In this embodiment, when the light intensity information does not meet the first condition, that is, it indicates that there is light in the current sliding window, it is necessary to continue sliding the sliding window to find the light-free zone. However, before continuing to slide the sliding window, it is necessary to determine whether the current optical signal sequence still contains optical signal points that have not entered the sliding window, that is, to determine whether the sliding window contains the last optical signal point of the optical signal sequence. If there are still optical signal points that have not entered the sliding window, the sliding window is continued to be slid to perform sliding window detection. If there are no optical signal points that have not entered the sliding window, it indicates that the optical signal output by the time-division multiplexed optical fiber hydrophone array currently obtained does not contain a light-free zone, and it is necessary to obtain the next optical signal output by the time-division multiplexed optical fiber hydrophone array to continue sliding window detection and determine the target sampling delay.

[0076] For example, in combination Figure 6 As shown in (c), the sliding window 103 is already at the last position of the optical signal sequence, and the sliding window cannot slide backward any further, so it is necessary to obtain a new optical signal output by the time-division multiplexed optical fiber hydrophone array.

[0077] Step S22: taking the starting position of the first target window as the target sampling delay.

[0078] For example, in combination Figure 6 As shown, for example Figure 6 The sliding window 102 in (b) is the first target window. Figure 6 The starting position of the sliding window 102 marked in is A2, and the ending position is B2. Then the starting position of the first target window is A2, and the time corresponding to A2 is the target sampling delay.

[0079] In this embodiment, sliding window detection is performed to obtain an initial target sampling delay, where the initial target sampling delay is the sampling delay required for demodulating the spectrum.

[0080] Step S3, determining an error ratio corresponding to the target sampling delay according to the target sampling delay and the optical signal.

[0081] In this step, the initial target sampling delay determined in step S2 is used for sampling to determine the error ratio of the initial target sampling delay during sampling. If the error ratio is larger, it proves that the initial target sampling delay has more errors. After the error ratio is greater than the preset value, it is necessary to adjust the initial target sampling delay and determine the current target sampling delay to improve the accuracy of the target sampling delay.

[0082] Optionally, step S3 includes steps S31 to S34, which are specifically as follows: Step S31, taking the rising edge of the first pulse in the optical signal as the starting point, after a target sampling delay, collecting a sub-signal interval of a preset length in the optical signal, and recording a detection record.

[0083] Step S32, calculating the light intensity information in the sub-signal interval.

[0084] Step S33: When the light intensity information does not satisfy the first condition, an error record is recorded.

[0085] Step S34, calculating the error ratio of the first number to the second number, the first number is the number of error records, and the second number is the number of detection records.

[0086] In this embodiment, by sampling the optical signal according to the target sampling delay, whether the target sampling delay is accurate is determined by the number of errors (the first number) and the number of detections (the second number), so that it is easy to redetermine the target sampling delay when it is inaccurate, thereby realizing automatic adjustment of the target sampling delay.

[0087] Optionally, step S34 further includes step S5, which is specifically as follows: Step S5, when the error ratio is less than or equal to the preset value, take the rising edge of the second pulse in the optical signal as the starting point, after the target sampling delay, collect the sub-signal interval of the preset length in the optical signal, record a detection record, and jump to step S32.

[0088] In this embodiment, when the error ratio is less than or equal to the preset value, it indicates that the accuracy of the initial target sampling delay still meets the requirements, so the initial target sampling delay can continue to be used for sampling and demodulation. Therefore, the second pulse is sampled again according to the initial target sampling delay, and the error ratio is continuously updated according to steps S32 to S34.

[0089] Step S4: When the error ratio is greater than a preset value, the target sampling delay is adjusted based on the sliding window technology and the optical signal.

[0090] In this step, when the error ratio is greater than the preset value, it means that the initial target sampling delay is no longer applicable, and the target sampling delay needs to be re-determined to achieve automatic adjustment of the target sampling delay.

[0091] Optionally, step S4 includes steps S41 to S43, which are specifically as follows: Step S41, starting from the first target window, the sliding window continues to slide across the optical signal sequence, and determines the light intensity information of all optical signal points in the window corresponding to the sliding window.

[0092] Step S42: when the light intensity information satisfies the first condition, stop sliding the sliding window and determine the sliding window as the second target window.

[0093] Step S43: determine the starting position of the second target window as the target sampling delay.

[0094] In this embodiment, the sliding window is continuously slid to determine the current target sampling delay, thereby facilitating the use of the new target sampling delay to sample and demodulate the optical signal, thereby improving the accuracy of the target sampling delay.

[0095] For example, in combination Figure 6 As shown, Figure 6 The sliding window 101 in (a) is the first target window. Step S41 is to slide the sliding window 101 according to a preset step value (such as the preset step value = 1) to obtain Figure 6 The sliding window 102 shown in (b) in FIG. 1 satisfies the first condition for the light intensity information of all optical signal points in the sliding window 102, and the sliding window 102 is the second target window. Then, the starting position A2 of the second target window (sliding window 102) is the target sampling delay.

[0096] Optionally, after step S4, step S6 is further included, which is specifically as follows: Step S6, jump to step S3.

[0097] In this embodiment, after obtaining the current target sampling delay, the current target sampling delay is detected again according to step S3 and step S4. If the error ratio of the current target sampling delay is greater than the preset value again, that is, the current target sampling delay cannot meet the accuracy requirement, it is necessary to continue to adjust and determine the target sampling delay again to achieve automatic adjustment of the target sampling delay.

[0098] By using the automatic adjustment method for sampling delay of a time-division multiplexed optical fiber hydrophone array provided in the embodiment of the present application, the target sampling delay can be determined according to the optical signal output by the time-division multiplexed optical fiber hydrophone array. If many errors occur when sampling using the target sampling delay, the target sampling delay can be automatically adjusted according to the optical signal output by the time-division multiplexed optical fiber hydrophone array, thereby realizing automatic adjustment of the target sampling delay. The sampling delay of the time-division channel can be measured in real time and accurately during the operation of the time-division multiplexed optical fiber hydrophone array, and automatic correction can be performed to ensure the long-term stable operation of the automatic adjustment system for sampling delay of the time-division multiplexed optical fiber hydrophone array. Not only can the measurement and automatic control of time-division pulse sampling delay be realized without human intervention, but also the autonomous working ability of the automatic adjustment system for sampling delay of the time-division multiplexed optical fiber hydrophone array for different array states can be improved, thereby improving the automation level of the system.

[0099] Figure 7 This is a second flow chart of the method for automatically adjusting the sampling delay of a time-division multiplexed optical fiber hydrophone array provided in an embodiment of the present application.

[0100] Specifically, combined Figure 7 As shown, the method for automatically adjusting the sampling delay of a time-division multiplexed optical fiber hydrophone array includes steps S01 to S04, which are specifically as follows: Step S01: the signal acquisition module 7 samples the interference light output by the optical fiber hydrophone array to obtain an optical signal sequence.

[0101] In this step, the interference light output by the time-division multiplexed optical fiber hydrophone array is converted into an electrical signal using the photoelectric conversion module 6, and then the electrical signal is converted into a digital signal using the signal acquisition module 7.

[0102] Step S02: Use a sliding window to slide and detect the optical signal sequence to determine the target sampling delay.

[0103] Specifically, the process of implementing step S02 refers to the above step S2, and this application will not repeat it here.

[0104] Step S03: sampling the optical signal sequence based on the target sampling delay, and recording the number of samplings and the number of errors.

[0105] Specifically, the process of implementing step S03 refers to the above step S3, and this application will not repeat it here.

[0106] Step S04, determining whether the error ratio is greater than a preset value.

[0107] In this step, if the error ratio is greater than the preset value, jump to step S02 to readjust the target sampling delay. If the error ratio is less than or equal to the preset value, jump to step S03 to continue sampling using the target sampling delay.

[0108] Corresponding to the embodiment of the aforementioned time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment method, the present application also provides an embodiment of a time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment device. The time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment system includes: a laser module, a time-division multiplexed optical fiber hydrophone array and a delay detection module. The laser module is configured to output a laser signal to the time-division multiplexed optical fiber hydrophone array according to the basic working parameters of the time-division multiplexed optical fiber hydrophone array. The time-division multiplexed optical fiber hydrophone array is configured to receive the output laser signal and output an optical signal. The delay detection module is configured as follows: S1: acquiring the optical signal output by the time-division multiplexed optical fiber hydrophone array; S2: determining the target sampling delay based on the sliding window technology and the optical signal, the target sampling delay being the difference between the moment when the time-division multiplexed optical fiber hydrophone array receives the optical pulse and the moment when the output optical signal is sampled; S3: determining the error ratio corresponding to the target sampling delay based on the target sampling delay and the optical signal; S4: when the error ratio is greater than a preset value, adjusting the target sampling delay based on the sliding window technology and the optical signal.

[0109] By using the automatic adjustment method for sampling delay of a time-division multiplexed optical fiber hydrophone array provided in the embodiment of the present application, it is possible to obtain the optical signal output by the time-division multiplexed optical fiber hydrophone array based on the delay detection module, and then determine the target sampling delay according to the optical signal output by the time-division multiplexed optical fiber hydrophone array. If many errors occur when sampling using the target sampling delay, the target sampling delay can be automatically adjusted according to the optical signal output by the time-division multiplexed optical fiber hydrophone array, thereby realizing automatic adjustment of the target sampling delay. The sampling delay of the time-division channel can be measured in real time and accurately during the operation of the time-division multiplexed optical fiber hydrophone array, and automatic correction can be performed to ensure the long-term stable operation of the automatic adjustment system for sampling delay of the time-division multiplexed optical fiber hydrophone array. Not only can the measurement and automatic control of time-division pulse sampling delay be realized without human intervention, but also the autonomous working ability of the automatic adjustment system for sampling delay of the time-division multiplexed optical fiber hydrophone array for different array states can be improved, thereby improving the automation level of the system.

[0110] It should be noted that those skilled in the art will easily think of other embodiments of the present application after considering the specification and practicing the application disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary technical means in the art that are not disclosed in the present application. The specification and examples are only regarded as exemplary, and the true scope of the present application is indicated by the claims.

[0111] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for automatically adjusting sampling delay of a time-division multiplexed optical fiber hydrophone array, characterized in that: include: S1: Acquire the optical signal output by the time-division multiplexed optical fiber hydrophone array; S2: Based on the sliding window technology and the optical signal, determine the target sampling delay, where the target sampling delay is the difference between the time when the time-division multiplexing optical fiber hydrophone array receives the optical pulse and the time when the output optical signal is sampled; S3: determining an error ratio corresponding to the target sampling delay according to the target sampling delay and the optical signal; S4: When the error ratio is greater than a preset value, adjusting the target sampling delay based on the sliding window technology and the optical signal.

2. The method for automatically adjusting sampling delay of a time-division multiplexed optical fiber hydrophone array according to claim 1, characterized in that: The optical signal comprises an optical signal sequence composed of a plurality of optical signal points; The determining of the target sampling delay based on the sliding window technology and the optical signal includes: Based on the sliding window detection, a first target window is determined; the first target window is the light intensity information of all the light signal points in the window of the sliding window that meets the first condition; The starting position of the first target window is used as the target sampling delay.

3. The method for automatically adjusting sampling delay of a time-division multiplexed optical fiber hydrophone array according to claim 2, characterized in that: The light intensity information includes the light intensity average and variance of all light signal points within the sliding window, and the first condition is that the light intensity average is less than the first light intensity average and the variance is less than the first variance.

4. The method for automatically adjusting sampling delay of a time-division multiplexed optical fiber hydrophone array according to claim 2, characterized in that: The determining of the first target window based on sliding window detection includes: Sliding the sliding window from the initial position of the optical signal sequence to slide across the optical signal sequence, and determining light intensity information of all optical signal points in the window corresponding to the sliding window; the length of the sliding window is a preset length, and the preset length is less than the total number of optical signal points in the optical signal sequence; the step value of the sliding window is a preset step value; When the light intensity information satisfies the first condition, the sliding of the sliding window is stopped, and the sliding window is determined to be the first target window.

5. The method for automatically adjusting sampling delay of a time-division multiplexed optical fiber hydrophone array according to claim 4, characterized in that: After sliding the sliding window from the initial position of the optical signal sequence to slide across the optical signal sequence and determining the light intensity information of all optical signal points in the window corresponding to the sliding window, the method further includes: When the light intensity information does not satisfy the first condition, determining whether the sliding window includes the last light signal point of the light signal sequence; In the case where the sliding window includes the last optical signal point of the optical signal sequence, jump to step S1; In the case that the sliding window does not include the last optical signal point of the optical signal sequence, the sliding window is slid according to the preset step value, and the light intensity information of all the optical signal points within the sliding window is calculated.

6. The method for automatically adjusting sampling delay of a time-division multiplexed optical fiber hydrophone array according to claim 1, characterized in that: The step of determining an error ratio corresponding to the target sampling delay according to the target sampling delay and the optical signal includes: S31: taking the rising edge of the first pulse in the optical signal as the starting point, collecting the sub-signal interval of the preset length in the optical signal after the target sampling delay, and recording a detection record; S32: Calculate the light intensity information in the sub-signal interval; S33: if the light intensity information does not meet the first condition, record an error record; S34: Calculate the error ratio of the first number to the second number, wherein the first number is the number of the error records, and the second number is the number of the detection records.

7. The method for automatically adjusting sampling delay of a time-division multiplexed optical fiber hydrophone array according to claim 2, characterized in that: When the error ratio is greater than a preset value, determining a target sampling delay based on the sliding window technology and the optical signal includes: Starting from the first target window, sliding the sliding window to continue sliding across the optical signal sequence, and determining light intensity information of all optical signal points in the window corresponding to the sliding window; When the light intensity information satisfies the first condition, stopping sliding the sliding window and determining the sliding window as a second target window; A starting position of the second target window is determined as the target sampling delay.

8. The method for automatically adjusting sampling delay of a time-division multiplexed optical fiber hydrophone array according to claim 6, characterized in that: After determining the error ratio corresponding to the target sampling delay according to the target sampling delay and the optical signal, the method further includes: When the error ratio is less than or equal to the preset value, the rising edge of the second pulse in the optical signal is taken as the starting point, the target sampling delay is separated, the sub-signal interval of the preset length in the optical signal is collected, and the detection record is recorded once, and the process jumps to step S32.

9. The method for automatically adjusting sampling delay of a time-division multiplexed optical fiber hydrophone array according to claim 1, characterized in that: After adjusting the target sampling delay based on the sliding window technology and the optical signal when the error ratio is greater than a preset value, the method further includes: Jump to step S3.

10. A time-division multiplexed optical fiber hydrophone array sampling delay automatic adjustment system, characterized in that: include: A laser module configured to output a laser signal into the time-division multiplexed optical fiber hydrophone array according to basic operating parameters of the time-division multiplexed optical fiber hydrophone array; The time-division multiplexing optical fiber hydrophone array is configured to receive the output laser signal and output an optical signal; The delay detection module is configured as S1: acquiring the optical signal output by the time division multiplexing optical fiber hydrophone array; S2: Based on the sliding window technology and the optical signal, determine the target sampling delay, where the target sampling delay is the difference between the time when the time-division multiplexing optical fiber hydrophone array receives the optical pulse and the time when the output optical signal is sampled; S3: determining an error ratio corresponding to the target sampling delay according to the target sampling delay and the optical signal; S4: When the error ratio is greater than a preset value, adjusting the target sampling delay based on the sliding window technology and the optical signal.

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