A frequency domain phase shift asynchronous resampling based frequency modulation nonlinear correction method

Abstract

The application provides a frequency domain phase shift asynchronous resampling-based frequency modulation nonlinear correction method. The method is realized based on a swept-frequency interference measuring device, and a series of calculations are performed on signals detected by two balanced detectors to determine the target distance. The application can inhibit the problem that the nonlinear correction effect is not ideal due to the unsynchronized light frequencies of an auxiliary interferometer and a measuring interferometer in the existing synchronous resampling frequency modulation nonlinear correction method, and the frequency domain phase shift resampling can make the correction more accurate, and the correction effect is not limited by the sampling rate.

Description

Technical Field

[0001] This invention relates to the field of frequency sweep interferometry technology based on frequency-modulated continuous wave, and in particular to a frequency-modulated nonlinear correction method based on frequency domain phase shift asynchronous resampling. Background Technology

[0002] Frequency-sweeping interferometry based on frequency-modulated continuous waves is an absolute distance measurement method that utilizes the constant optical frequency difference between the measurement light and the reference light in the interferometer to detect the absolute distance to the target. However, due to the nonlinear modulation of the optical frequency by the sweeping light source, the optical frequency difference changes nonlinearly over time, leading to degradation of the harmonicity of the measurement signal. The signal spectrum, representing the leakage of the target's main lobe energy to the side lobes, makes it impossible to determine the target's position through the spectrum. Classical methods for nonlinear correction, such as photoelectric phase-locked loops (PLLs), phase comparison methods, and resampling methods, are applied to nonlinear sweeping correction. However, the PLL method is physically difficult to implement and prone to loss of lock under rapid sweeping and strong nonlinearity, making it difficult to control the laser source to achieve a stable linear sweeping light output. The phase comparison method is limited by phase demodulation accuracy and cannot achieve multi-target phase detection, making it difficult to perform measurements in non-cooperative or multi-target co-path conditions. The resampling method, the most widely used method for solving nonlinear correction, struggles to guarantee the sweeping nonlinear correction effect across the entire range due to optical frequency asynchrony caused by interferometer optical path mismatch. To address the problems existing in the above methods, this invention proposes a frequency modulation nonlinearity correction method based on frequency domain phase shift asynchronous resampling. Summary of the Invention

[0003] The purpose of this invention is to solve the problems in the prior art by proposing a frequency modulation nonlinear correction method based on frequency domain phase shift asynchronous resampling.

[0004] This invention is achieved through the following technical solution: This invention proposes a frequency modulation nonlinearity correction method based on frequency domain phase shift asynchronous resampling, the method comprising:

[0005] Step 1: The measurement signal i is obtained by two balanced detectors. mea (t) and auxiliary signal i aux (t);

[0006] Step 2: For i in Step 1 mea (t) is subjected to a fast Fourier transform to obtain I mea (f), calculate I mea The frequency f corresponding to the maximum energy of (f) max1 , will f max1 Convert to coarse target distance R mea1 ;

[0007] Step 3: Based on the known length R of the auxiliary interferometer f R obtained in step 2 mea1Calculate the first-order discrete asynchronous quantity m required for asynchronous processing;

[0008] Step 4: For i in Step 1 aux (t) is the first-order asynchronous clock i obtained by asynchronous processing. auxm (t);

[0009] Step 5: Using i auxm The phase of (t) is the sampling clock, and the i obtained in step 1 is... mea (t) performs asynchronous resampling to obtain i in the k-domain mea1 (k);

[0010] Step 6: For i in step 5 mea1 (k) Perform a Fast Fourier Transform to obtain I mea1 (f), calculate I mea1 The frequency f corresponding to the maximum energy of (f) max2 , will f max2 Convert to coarse target distance R mea2 ;

[0011] Step 7: Based on the known length R of the auxiliary interferometer aux R obtained in step 6 mea2 Calculate the N consecutive asynchronous quantities τ1, τ2, ..., τ required for asynchronous processing. N ;

[0012] Step 8: For i in step 1 aux (t) is subjected to Fourier transform to obtain I aux (f) Using the τ1, τ2, ..., τ obtained in step 7 N Construct the phase shift factor exp(–j2πfτ) n ), to I aux (f) Perform a frequency domain phase shift, and then perform an inverse Fourier transform to the time domain to obtain N asynchronous clock signals i. aux1 (t),i aux2 (t),…,i auxN (t);

[0013] Step 9: For the N asynchronous clock signals i from step 8 aux1 (t),i aux2 (t),…,i auxN The phase of (t) is synthesized with different weights to obtain The weights of each asynchronous clock signal are γ1, γ2, ..., γ N ;

[0014] Step 10: with For the sampling clock, i obtained in step 1 mea (t) performs asynchronous resampling to obtain i in the k-domainmea2 (k), for i mea2 (k) Perform spectral analysis to determine the target distance R. mea .

[0015] Furthermore, in steps 1 and 2, the measurement signal i is obtained by the two balanced detectors respectively. mea (t) and auxiliary signal i aux (t):

[0016]

[0017] Among them, A mea A aux τ represents the amplitude of the measured signal and the auxiliary signal, respectively. mea , τ aux The propagation group delays of the measuring interferometer and the auxiliary interferometer are given by f0 and Δf, respectively. (n-1) (t) represents the initial optical frequency of the frequency-modulated light source and the n-1th derivative of Δf(t), respectively. Δf(t) is the sweep frequency nonlinear curve that varies with time, and N is the maximum order of the sweep frequency nonlinearity.

[0018] The coarse measurement value R of the target distance mea1 :

[0019]

[0020] Among them, f max1 For i mea The frequency corresponding to the maximum spectral energy of (t), where c is the speed of light, K is the modulation rate of the frequency-modulated light source, and n air is the refractive index in air.

[0021] Furthermore, in step 3, the first-order discrete asynchronous quantity m:

[0022]

[0023] Where, n g Fs represents the refractive index of the optical fiber, and Fs is the sampling frequency of the signal.

[0024] Furthermore, in step 4, for i in step 1 aux (t) is the first-order asynchronous clock i obtained by asynchronous processing. auxm (t):

[0025]

[0026] Where, τ mea1 The length of the interferometer is represented by R. mea1 Group delay, Representing i auxm(t) The 3rd to Nth order swept frequency nonlinear phase terms of the signal phase.

[0027] Furthermore, in steps 5 and 6, i auxm The phase of (t) is the sampling clock, and the i obtained in step 1 is... mea (t) performs asynchronous resampling to obtain i in the k-domain mea1 (k):

[0028]

[0029] Among them, i auxm Phase of (k) It varies linearly with k, k = 1, 2, 3, ... Representing i mea1 (k) Signal phase 3 to Nth order swept frequency nonlinear phase term;

[0030] The coarse measurement value R of the target distance mea2 :

[0031]

[0032] Among them, f max2 For i mea1 The frequency corresponding to the maximum spectral energy of (k).

[0033] Furthermore, in step 7, the following equation condition must be satisfied:

[0034]

[0035] Formula (8) represents the p-th equation. Solving the N equations yields the N asynchronous quantities τ1, τ2, ..., τ that can take continuous values, required for asynchronous processing. N The analytical expression, when N=2, is as follows:

[0036]

[0037] Furthermore, in steps 8 and 9, the N asynchronous clock signals i aux1 (t),i aux2 (t),…,i auxN (t):

[0038] i auxn (t) = IFFT[I aux (f)exp(-j2πfτ n )] n=1,2,3,...,N (11)

[0039] For the N asynchronous clock signals i in step 8 aux1 (t),i aux2 (t),…,iauxN The phase of (t) is synthesized with different weights to obtain The weights of each asynchronous clock signal are γ1, γ2, ..., γ N ;

[0040]

[0041] Further, in step 10, the... For the sampling clock, i obtained in step 1 mea (t) performs asynchronous resampling to obtain i in the k-domain mea2 (k):

[0042]

[0043] to i mea2 (k) Perform spectral analysis to determine the target distance R. mea :

[0044]

[0045] Among them, f max3 For i mea2 The frequency corresponding to the maximum spectral energy of (k).

[0046] The present invention also proposes an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the frequency modulation nonlinear correction method based on frequency domain phase shift asynchronous resampling.

[0047] The present invention also proposes a computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the steps of the frequency modulation nonlinear correction method based on frequency domain phase shift asynchronous resampling.

[0048] The beneficial effects of this invention are:

[0049] This invention can suppress the problem of unsatisfactory nonlinear correction effect caused by the asynchronous optical frequencies of the auxiliary interferometer and the measuring interferometer in the existing synchronous resampling frequency modulation nonlinear correction method. The use of frequency domain phase shift resampling can make the correction more accurate and the correction effect is not limited by the sampling rate. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0051] Figure 1 This is a schematic diagram of the optical path structure used in this invention;

[0052] Figure 2 This is a flowchart of a frequency modulation nonlinearity correction method based on frequency domain phase shift asynchronous resampling as described in this invention;

[0053] Figure 3 This is the experimental diagram in the process of this invention (Fs = 250MHz / s; R aux =15m; R mea ≈248m);

[0054] Figure 4 This is a single-target measurement spectrum experiment diagram (Fs = 250MHz / s; R aux =15m; R mea ≈250m; (a)~(c) represent the ranging spectrum after correction using the existing resampling method; (d)~(f) represent the ranging spectrum after processing using the method described in this invention.

[0055] Figure 5 This is a two-target ranging spectrum experimental diagram (Fs = 250 MHz / s; R aux =15m; the two targets are located around 248m; (a) to (b) represent the ranging spectrum after correction using the existing resampling method; (c) to (d) represent the ranging spectrum after processing using the method described in this invention, and the sub-figure in (d) represents an enlarged view of the ranging spectrum of the two targets). Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] The frequency-modulated nonlinear correction method based on asynchronous resampling in the frequency domain phase shift described in this invention is implemented using a swept-frequency interferometric measurement device. This swept-frequency interferometric measurement device is based on the optical path structure of a dual Mach-Zehnder interferometer, as shown below. Figure 1As shown, the swept light output from the frequency-modulated light source is split into measurement light and reference light by coupler 1, which then enter the measurement interferometer and auxiliary interferometer, respectively. The measurement light (splittered by coupler 2) enters the measurement arm of the measurement interferometer, passes through the circulator, exits from the optical system, is transmitted to the target surface for reflection, and the reflected light passes through the optical system and exits from the other end of the circulator. It is then combined with the reference light (splittered by coupler 3) entering the reference arm of the measurement interferometer at coupler 4 to form a measurement signal, which is detected by the balanced detector 1. The measurement light (splittered by coupler 2) and the reference light (splittered by coupler 3) entering the auxiliary interferometer pass through two optical fibers of different lengths and are combined at coupler 5 to form an auxiliary signal, which is detected by the balanced detector 2.

[0058] Specifically, in combination Figures 2-5 This invention proposes a frequency modulation nonlinearity correction method based on frequency domain phase shift asynchronous resampling, the method comprising:

[0059] Step 1: The measurement signal i is obtained by two balanced detectors. mea (t) and auxiliary signal i aux (t);

[0060] Step 2: For i in Step 1 mea (t) is subjected to a fast Fourier transform to obtain I mea (f), calculate I mea The frequency f corresponding to the maximum energy of (f) max1 , will f max1 Convert to coarse target distance R mea1 ;

[0061] Step 3: Based on the known length R of the auxiliary interferometer f R obtained in step 2 mea1 Calculate the first-order discrete asynchronous quantity m required for asynchronous processing;

[0062] Step 4: For i in Step 1 aux (t) is the first-order asynchronous clock i obtained by asynchronous processing. auxm (t);

[0063] Step 5: Using i auxm The phase of (t) is the sampling clock, and the i obtained in step 1 is... mea (t) performs asynchronous resampling to obtain i in the k-domain mea1 (k);

[0064] Step 6: For i in step 5 mea1 (k) Perform a Fast Fourier Transform to obtain I mea1 (f), calculate I mea1 The frequency f corresponding to the maximum energy of (f) max2 , will f max2Convert to coarse target distance R mea2 ;

[0065] Step 7: Based on the known length R of the auxiliary interferometer aux R obtained in step 6 mea2 Calculate the N consecutive asynchronous quantities τ1, τ2, ..., τ required for asynchronous processing. N ;

[0066] Step 8: For i in step 1 aux (t) is subjected to Fourier transform to obtain I aux (f) Using the τ1, τ2, ..., τ obtained in step 7 N Construct the phase shift factor exp(–j2πfτ) n ), to I aux (f) Perform a frequency domain phase shift, and then perform an inverse Fourier transform to the time domain to obtain N asynchronous clock signals i. aux1 (t),i aux2 (t),…,i auxN (t);

[0067] Step 9: For the N asynchronous clock signals i from step 8 aux1 (t),i aux2 (t),…,i auxN The phase of (t) is synthesized with different weights to obtain The weights of each asynchronous clock signal are γ1, γ2, ..., γ N ;

[0068] Step 10: with For the sampling clock, i obtained in step 1 mea (t) performs asynchronous resampling to obtain i in the k-domain mea2 (k), for i mea2 (k) Perform spectral analysis to determine the target distance R. mea .

[0069] In step 1, the measurement signal i is obtained by two balanced detectors respectively. mea (t) and auxiliary signal i aux (t):

[0070]

[0071] Among them, A mea A aux τ represents the amplitude of the measured signal and the auxiliary signal, respectively. mea , τ aux The propagation group delays of the measuring interferometer and the auxiliary interferometer are given by f0 and Δf, respectively. (n-1)(t) represents the initial optical frequency of the frequency-modulated light source and the n-1th derivative of Δf(t), respectively. Δf(t) is the sweep frequency nonlinear curve that varies with time, and N is the maximum order of the sweep frequency nonlinearity.

[0072] In step 2, for i in step 1 mea (t) is subjected to a fast Fourier transform to obtain I mea (f), the experimental results are as follows Figure 3 As shown in (a), calculate I. mea The frequency f corresponding to the maximum energy of (f) max1 , will f max1 Convert to coarse target distance R mea1 The target distance coarse measurement value R mea1 :

[0073]

[0074] Among them, f max1 For i mea The frequency corresponding to the maximum spectral energy of (t), where c is the speed of light, K is the modulation rate of the frequency-modulated light source, and n air is the refractive index in air.

[0075] In step 3, the first-order discrete asynchronous quantity m:

[0076]

[0077] Where, n g Fs represents the refractive index of the optical fiber, and Fs is the sampling frequency of the signal.

[0078] In step 4, for i in step 1 aux (t) is the first-order asynchronous clock i obtained by asynchronous processing. auxm (t):

[0079]

[0080] Where, τ mea1 The length of the interferometer is represented by R. mea1 Group delay, Representing i auxm (t) The 3rd to Nth order swept frequency nonlinear phase terms of the signal phase.

[0081] In step 5, i auxm The phase of (t) is the sampling clock, and the i obtained in step 1 is... mea (t) performs asynchronous resampling to obtain i in the k-domain mea1 (k):

[0082]

[0083] Among them, i auxm Phase of (k) It varies linearly with k, k = 1, 2, 3, ... Representing i mea1 (k) Signal phase 3 to Nth order swept frequency nonlinear phase term;

[0084] In step 6, for i in step 5 mea1 (k) Perform a Fast Fourier Transform to obtain I mea1 (f), the experimental results are as follows Figure 3 As shown in (b), calculate I. mea1 The frequency f corresponding to the maximum energy of (f) max2 , will f max2 Convert to coarse target distance R mea2 The target distance coarse measurement value R mea2 :

[0085]

[0086] Among them, f max2 For i mea1 The frequency corresponding to the maximum spectral energy of (k).

[0087] In step 7, the following equation condition must be satisfied:

[0088]

[0089] Formula (8) represents the p-th equation. Solving the N equations yields the N asynchronous quantities τ1, τ2, ..., τ that can take continuous values, required for asynchronous processing. N The analytical expression, when N=2, is as follows:

[0090]

[0091] In step 8, for step 1, i aux (t) is subjected to Fourier transform to obtain I aux (f) Using the τ1, τ2, ..., τ obtained in step 7 N Construct the phase shift factor exp(–j2πfτ) n ), to I aux (f) Perform a frequency domain phase shift, and then perform an inverse Fourier transform to the time domain to obtain N asynchronous clock signals i. aux1 (t),i aux2 (t),…,i auxN (t); the N asynchronous clock signals i aux1 (t),i aux2 (t),…,i auxN (t):

[0092] i auxn (t) = IFFT[I aux (f)exp(-j2πfτ n )] n=1,2,3,...,N (11)

[0093] In step 9, the N asynchronous clock signals i from step 8 are... aux1 (t),i aux2 (t),…,i auxN The phase of (t) is synthesized with different weights to obtain The weights of each asynchronous clock signal are γ1, γ2, ..., γ N ;

[0094]

[0095] In step 10, the use of For the sampling clock, i obtained in step 1 mea (t) performs asynchronous resampling to obtain i in the k-domain mea2 (k):

[0096]

[0097] to i mea2 (k) Perform spectral analysis, and the experimental results are as follows: Figure 3 As shown in (c), the target distance R is determined. mea :

[0098]

[0099] Among them, f max3 For i mea2 The frequency corresponding to the maximum spectral energy of (k).

[0100] Figure 4 and Figure 5 The results represent the measurement results of a single target and a dual target after applying existing resampling methods and the method described in this invention, respectively.

[0101] The present invention also proposes an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the frequency modulation nonlinear correction method based on frequency domain phase shift asynchronous resampling.

[0102] The present invention also proposes a computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the steps of the frequency modulation nonlinear correction method based on frequency domain phase shift asynchronous resampling.

[0103] The memory in this application embodiment can be volatile memory or non-volatile memory, or it can include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DRRAM). It should be noted that the memory used in the methods described in this invention is intended to include, but is not limited to, these and any other suitable types of memory.

[0104] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., high-density digital video discs (DVDs)), or semiconductor media (e.g., solid-state disks (SSDs)).

[0105] In implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software. The steps of the method disclosed in the embodiments of this application can be directly implemented by a hardware processor, or by a combination of hardware and software modules in the processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, detailed descriptions are omitted here.

[0106] It should be noted that the processor in the embodiments of this application can be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method embodiments can be completed by the integrated logic circuitry in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied as being executed by a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above methods.

[0107] The above provides a detailed description of the frequency modulation nonlinear correction method based on asynchronous resampling in the frequency domain phase shift proposed in this invention. Specific examples have been used to illustrate the principle and implementation of this invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A frequency modulation nonlinearity correction method based on frequency domain phase-shift asynchronous resampling, characterized in that, The method includes: Step 1: Measurement signal i is obtained from two balanced probes mea (t) with auxiliary signal i aux (t); Step 2: i of Step 1 mea (t) performing a fast Fourier transform to obtain I mea (f), calculating the frequency f mea corresponding to the energy maximum of I max1 (f) max1 converting f mea1 to a target distance coarse value R Step 3: Calculate the length R of the known auxiliary interferometer f R = R + R mea1 , calculate the first-order discrete asynchronous amount m required for asynchronous processing; Step 4: i of step 1 is paired with the first-order asynchronous clock i obtained by asynchronous processing aux (t) is paired with the first-order asynchronous clock i obtained by asynchronous processing auxm (t); Step 5: i auxm (t) is resampled asynchronously with the phase of the sampling clock to obtain i mea (k) in the k domain. mea1 (k) in the k domain. Step 6: For i in step 5 mea1 (k) Perform a Fast Fourier Transform to obtain I mea1 (f), calculate I mea1 The frequency f corresponding to the maximum energy of (f) max2 , will f max2 Convert to coarse target distance R mea2 ; Step 7: Based on the known length R of the auxiliary interferometer aux R obtained in step 6 mea2 Calculate the N consecutive asynchronous quantities τ1, τ2, ..., τ required for asynchronous processing. N ; Step 8: For i in step 1 aux (t) is subjected to Fourier transform to obtain I aux (f) Using the τ1, τ2, ..., τ obtained in step 7 N Construct the phase shift factor exp(–j2πfτ) n ), to I aux (f) Perform a frequency domain phase shift, and then perform an inverse Fourier transform to the time domain to obtain N asynchronous clock signals i. aux1 (t),i aux2 (t),…,i auxN (t); Step 9: For the N asynchronous clock signals i from step 8 aux1 (t),i aux2 (t),…,i auxN The phase of (t) is synthesized with different weights to obtain The weights of each asynchronous clock signal are γ1, γ2, ..., γ N ; Step 10: with For the sampling clock, i obtained in step 1 mea (t) performs asynchronous resampling to obtain i in the k-domain mea2 (k), for i mea2 (k) Perform spectral analysis to determine the target distance R. mea .

2. The method according to claim 1, characterized in that, In steps 1 and 2, the measurement signal i is obtained by the two balanced detectors respectively. mea (t) and auxiliary signal i aux (t): Among them, A mea A aux τ represents the amplitudes of the measured signal and the auxiliary signal, respectively. mea , τ aux The propagation group delays of the measuring interferometer and the auxiliary interferometer are given by f0 and Δf, respectively. (n-1) (t) represents the initial optical frequency of the frequency-modulated light source and the n-1th derivative of Δf(t), respectively. Δf(t) is the sweep frequency nonlinear curve that varies with time, and N is the maximum order of the sweep frequency nonlinearity. The coarse measurement value R of the target distance mea1 : Among them, f max1 For i mea The frequency corresponding to the maximum spectral energy of (t), where c is the speed of light, K is the modulation rate of the frequency-modulated light source, and n air is the refractive index in air.

3. The method according to claim 2, characterized in that, In step 3, the first-order discrete asynchronous quantity m: Where, n g Fs represents the refractive index of the optical fiber, and Fs is the sampling frequency of the signal.

4. The method according to claim 3, characterized in that, In step 4, for i in step 1 aux (t) is the first-order asynchronous clock i obtained by asynchronous processing. auxm (t): Where, τ mea1 The length of the interferometer is represented by R. mea1 Group delay, Representing i auxm (t) The 3rd to Nth order swept frequency nonlinear phase terms of the signal phase.

5. The method according to claim 4, characterized in that, In steps 5 and 6, i auxm The phase of (t) is the sampling clock, and the i obtained in step 1 is... mea (t) performs asynchronous resampling to obtain i in the k-domain mea1 (k): Among them, i auxm Phase of (k) It varies linearly with k, k = 1, 2, 3, ... Representing i mea1 (k) Signal phase 3 to Nth order swept frequency nonlinear phase term; The coarse measurement value R of the target distance mea2 : Among them, f max2 For i mea1 The frequency corresponding to the maximum spectral energy of (k).

6. The method according to claim 5, characterized in that, In step 7, the following equation condition must be satisfied: Formula (8) represents the p-th equation. Solving the N equations yields the N asynchronous quantities τ1, τ2, ..., τ that can take continuous values, required for asynchronous processing. N The analytical expression, when N=2, is as follows:

7. The method according to claim 6, characterized in that, In steps 8 and 9, the N asynchronous clock signals i aux1 (t),i aux2 (t),…,i auxN (t): i auxn (t)=IFFT[I aux (f)exp(-j2πfτ n )] n=1,2,3,...,N (11) For the N asynchronous clock signals i in step 8 aux1 (t),i aux2 (t),…,i auxN The phase of (t) is synthesized with different weights to obtain The weights of each asynchronous clock signal are γ1, γ2, ..., γ N ; 8. The method according to claim 7, characterized in that, In step 10, the use of For the sampling clock, i obtained in step 1 mea (t) performs asynchronous resampling to obtain i in the k-domain mea2 (k): to i mea2 (k) Perform spectral analysis to determine the target distance R. mea : Among them, f max3 For i mea2 The frequency corresponding to the maximum spectral energy of (k).

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1-8.

10. A computer-readable storage medium for storing computer instructions, characterized in that, When the computer instructions are executed by the processor, they implement the steps of the method according to any one of claims 1-8.

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