Phase shift amplification modulation depth normalization method for optical carrier microwave interferometric distance measurement system

Abstract

The application provides a phase shift amplification modulation depth normalization method for an optical carrier microwave interferometric distance measurement system, and relates to the field of distance measurement, and comprises the following steps: extracting amplitude-frequency characteristic data and phase-frequency characteristic data; in amplitude-frequency characteristic data analysis, obtaining an amplitude ratio of the amplitude-frequency characteristic according to a maximum minimum power ratio and combining image contrast analysis; normalizing the frequency; in phase-frequency characteristic data analysis, obtaining local minimum values and maximum values according to a phase-frequency characteristic curve, and calculating normalized parameters corresponding to the local minimum values and the maximum values; generating a table according to the phase shift amplification technology; obtaining an amplitude ratio of the phase-frequency characteristic by querying the table; selecting an optimal amplitude ratio to obtain a normalized phase-frequency characteristic curve; establishing a phase shift and distance change linear representation model according to the phase shift amplification technology, and calculating the distance change according to a center frequency of the phase-frequency characteristic curve. The technical scheme of the application overcomes the problem that modulation depth is not normalized in the prior art, and precise distance measurement cannot be realized.

Description

Technical Field

[0001] The present invention relates to the field of distance measurement, and in particular to a method for normalizing the phase shift amplification modulation depth of an optical microwave interferometric distance measurement system. Background Art

[0002] Optical microwave interferometry is a distance measurement solution, and phase-shift amplification is a highly sensitive phase detection method based on optical microwave interferometry. Its core is to linearly amplify tiny phase changes caused by, for example, changes in the measured distance at the destructive interference point. Furthermore, optical RF phase-shift amplification amplifies the signal phase without amplifying the input phase noise, and can effectively suppress laser intensity noise (such as relative intensity noise, RIN) and scattering noise, thereby significantly improving system sensitivity. In recent years, research on phase-shift amplification technology in the fields of precision ranging and material refractive index has shown rapid development. Its core lies in improving signal processing capabilities through phase control, providing technical support for high-precision distance detection.

[0003] Figure 13 、 14 The example experiments characterized represent the amplitude spectra under different distance measurements under the same experimental conditions. The original amplitude refers to the measurement distance not set, which can be intuitively understood as the measured distance is basically 0. Example experiments one to four use a high-precision displacement device to set incremental precision distance changes. For example, example experiments one to four are: 0.1 , 0.3 , 0.5 , 0.6 According to the principle of optical microwave interferometry ranging, ideally, as the measured distance increases, the symmetrical midpoint of the curve, that is, the local minimum, should become deeper as the distance increases. However, in high-precision ranging, the amount of coupling introduced by the distance change should be negligible, so the steepness of the curve should be basically consistent.

[0004] Depend on Figure 14 As can be seen, the steepness of the amplitude-frequency curve near its symmetrical midpoint varies. This indicates that in this experimental system, the amplitude ratio between the optical path and the microwave path varies with each experiment due to various interferences during light transmission. The lower the symmetrical midpoint of the curve, the closer the two amplitudes are, that is, the closer the amplitude ratio is to 1. However, different amplitude ratios will make it impossible to process the data using phase-shift amplification technology. The application of phase-shift amplification technology requires the same gain conditions. In other words, it cannot be used directly without processing, and the measured distance data cannot be demodulated. Therefore, the amplitude ratio must be controlled to maintain a constant value. Therefore, in the amplitude-frequency characteristics of phase-shift amplification technology, precise distance measurement cannot be achieved due to the unnormalized amplitude ratio.

[0005] Figure 15 、 16 The example experiments described are similar, representing the phase spectra under different distance measurements under the same experimental conditions. The original phase frequency refers to the measurement distance not being set, which can be intuitively understood as the measured distance being basically 0. For example experiments one to four, a high-precision displacement device is used to set incremental precision distance changes. For example, example experiments one to four are: 0.1 , 0.3 , 0.5 , 0.6 According to the principle of optical microwave interferometry ranging, ideally, as the distance to be measured increases, the phase shift curve in high-precision ranging should be minimal due to the coupling introduced by the distance change, so the shape of the phase-frequency curve should be basically consistent.

[0006] In the phase-frequency characteristic curve, the inconsistent amplitude ratio causes the slope of the phase-frequency characteristic curve to change between the minimum and maximum values. The larger the slope, the closer the amplitude ratio is to 1. Due to the influence of systematic errors, the phase-frequency curve shape shifts. Therefore, the phase-frequency and amplitude-frequency results confirm that without normalizing the gain, that is, the amplitude ratio, of each experiment, the application conditions of the optical RF phase-shift amplification technology are not met, and demodulation of the distance change cannot be measured. Therefore, it is necessary to first normalize the data by amplitude ratio to ensure that all experimental data are analyzed under the same amplitude ratio. Therefore, in the phase-frequency characteristic of the phase-shift amplification technology, precise distance measurement cannot be achieved due to the unnormalized amplitude ratio.

[0007] Therefore, a method for normalizing the phase shift amplification modulation depth of an optical microwave interferometer ranging system that can achieve precise ranging is needed. Summary of the Invention

[0008] The main purpose of the present invention is to provide a method for normalizing the phase shift amplification modulation depth of an optical microwave interferometer ranging system, so as to solve the problem in the prior art that the modulation depth is not normalized and precise distance measurement cannot be achieved.

[0009] To achieve the above object, the present invention provides a method for normalizing the phase shift amplification modulation depth of an optical microwave interferometer ranging system, which specifically comprises the following steps:

[0010] S1, collects the original data of microwave signals from the optical microwave interferometry ranging experiment, and extracts the amplitude-frequency characteristic data and phase-frequency characteristic data respectively.

[0011] S2, in the amplitude-frequency characteristic data analysis, according to the maximum and minimum power ratio , and combined with image comparison analysis, the amplitude ratio of the amplitude-frequency characteristic is obtained .

[0012] S3, normalizing the frequency.

[0013] S4, in the phase-frequency characteristic data analysis, first, the phase is disentangled, the 2π period characteristic is eliminated, then the system linear trend phase is removed, the local minimum value and the maximum value are obtained according to the phase-frequency characteristic curve, and the normalized parameters corresponding to the local minimum value and the maximum value are calculated.

[0014] S5, according to the phase shift amplification technology, the artificially set and corresponding , , and are generated, and a table is generated.

[0015] S6, using the , , and obtained in step S4, the amplitude ratio of the phase-frequency characteristic is obtained by querying the table.

[0016] S7, comparing the and of multiple groups of optical microwave interferometric ranging experiments, selecting the amplitude ratio of the phase-frequency characteristic in the group of experiments closest to and as the best amplitude ratio, and normalizing the amplitude ratio of the phase-frequency characteristic in the remaining experiments to the selected best amplitude ratio, to obtain the normalized phase-frequency characteristic curve.

[0017] S8, according to the phase shift amplification technology, a phase shift and measurement distance change linear representation model is established, and the distance change is calculated according to the center frequency of the phase-frequency characteristic curve in step S7.

[0018] Further, step S2 specifically includes the following steps:

[0019] S2.1, assuming that the two-way radio frequency signals are and :

[0020] ;

[0021] wherein, and respectively represent the initial phase of and , represents the angular frequency, is the amplitude in the measurement link, is the reference link amplitude.

[0022] S2.2, after the two signals are superimposed, the synthesized signal for:

[0023] ;

[0024] Among them, the composite phase of the signal Expressed as:

[0025] .

[0026] Composite amplitude of superimposed signals Expressed as:

[0027] ;

[0028] = ;

[0029] in, For phase.

[0030] S2.3, according to the amplitude-frequency characteristic curve, find the corresponding maximum and minimum power points within a cycle. The power reaches its maximum value when The maximum-minimum power ratio is :

[0031] ;

[0032] After simplification, we have:

[0033] ;

[0034] Arrange both sides of the equation and solve it using the phase-frequency characteristic curve :

[0035] .

[0036] Furthermore, step S3 is specifically as follows:

[0037] ;

[0038] ;

[0039] in, is the angular frequency, is the rough optical path difference, is the speed of light, is the center frequency of the phase-frequency characteristic curve, is the free spectral range, Frequency normalized parameters.

[0040] Furthermore, step S4 is specifically as follows:

[0041] Obtaining the local minimum value based on the phase-frequency characteristic curve and maximum value , and calculate the local minimum and maximum value Corresponding , .

[0042] Furthermore, the normalization processing formula in step S7 is:

[0043] ;

[0044] in, is the optimal amplitude ratio selected, is the amplitude ratio to be normalized, is the phase to be normalized, is the normalized phase.

[0045] Furthermore, step S8 is specifically as follows:

[0046] ;

[0047] ;

[0048] in, is the distance change, is the phase difference.

[0049] The present invention has the following beneficial effects:

[0050] (1) The modulation depth normalization algorithm of the present invention is based on the joint analysis of the amplitude-frequency and phase-frequency characteristics, which solves the problem of inconsistent amplitude ratio caused by power fluctuation in the existing optical microwave interferometer system.

[0051] (2) A matching mechanism between the power extreme value ratio and the frequency characteristic point in the amplitude-frequency characteristic was constructed, and the slope analysis of the phase-frequency characteristic curve was combined to perform bidirectional screening and correction of the modulation depth, thereby improving the accuracy of obtaining the amplitude ratio.

[0052] (3) The tabulation and table lookup method is introduced to realize the quantitative mapping between the slope of the phase-frequency characteristic curve and the amplitude ratio, providing an efficient and practical means of solving the modulation depth in phase-shift amplification technology.

[0053] (4) The linear characterization model between phase shift and distance measurement change is used to provide theoretical and methodological support for high-sensitivity displacement measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0055] Figure 1 The flowchart of the present invention shows a method for normalizing the phase shift amplification modulation depth of an optical microwave interferometric ranging system.

[0056] Figure 2 Shown is a diagram of the optical microwave interferometry ranging experimental system.

[0057] Figure 3 The amplitude-frequency characteristic curve of a certain experiment is shown.

[0058] Figure 4 Shown Figure 3 A magnified detail of point O.

[0059] Figure 5 Shows when The corresponding phase-frequency characteristic curve.

[0060] Figure 6 Shows when The corresponding phase-frequency characteristic curve.

[0061] Figure 7 Shows when or The corresponding phase-frequency characteristic curve.

[0062] Figure 8 The original phase-frequency curve is shown.

[0063] Figure 9 The phase-frequency curve of the phase that eliminates the linear trend of the system is shown.

[0064] Figure 10 An example diagram of free spectrum range distance measurement is shown.

[0065] Figure 11 Phase-frequency curves under different tests are shown.

[0066] Figure 12 The modulation depth normalized phase-frequency plot is shown.

[0067] Figure 13 The amplitude-frequency characteristic curve of the phase shift amplification technology is shown.

[0068] Figure 14 Shown Figure 13 A magnified detail of point A.

[0069] Figure 15 The phase-frequency characteristic curve of the phase-shift amplification technology is shown.

[0070] Figure 16 Shown Figure 15 A magnified view of the detail at point B. DETAILED DESCRIPTION

[0071] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0072] like Figure 1 The method for normalizing the phase shift amplification modulation depth of an optical microwave interferometric ranging system shown in the figure specifically includes the following steps:

[0073] S1, collects the original data of microwave signals from the optical microwave interferometry ranging experiment, and extracts the amplitude-frequency characteristic data and phase-frequency characteristic data respectively.

[0074] S2, in the amplitude-frequency characteristic data analysis, according to the maximum and minimum power ratio , and combined with image comparison analysis, the amplitude ratio of the amplitude-frequency characteristic is obtained .

[0075] S3, normalize the frequency.

[0076] S4, in the phase-frequency characteristic data analysis, first phase unwrapping is performed to eliminate the 2π periodic characteristics, then the linear trend phase of the system is eliminated, and the local minimum is obtained according to the phase-frequency characteristic curve. and maximum value , and calculate the local minimum and maximum value The corresponding normalized parameters. After calculating the corresponding amplitude ratio information based on the amplitude information, it is necessary to explore the amplitude ratio under the phase-frequency characteristic. Under each set of experimental data, the phase-frequency characteristic curve has a 2π period. After the phase is expanded, the 2π period characteristic is eliminated. Figure 8 As shown in Figure 2, after phase unwrapping, there is no 2π periodic characteristic, and the phase-frequency characteristic data is restored to facilitate discussion and calculation.

[0077] In order to eliminate the linear trend of the system, the present invention adopts a phase calibration method based on the interference cancellation point. Since the interference cancellation point has a theoretical phase of zero, a linear function is constructed to obtain the true system phase response.

[0078] In the phase shift amplification technology, the amplitude ratio occurs at the phase frequency point where the interference is canceled, and the phase must be 0°. The phase frequency curve is a The key to eliminating the linear function is to calibrate the interference cancellation point and then eliminate curve, and then make the difference.

[0079] ;

[0080] in, is the total phase actually measured; is the demodulated phase to be obtained; It is the linear trend phase of the system.

[0081] Let the frequency at the interference cancellation point in this figure be 、 , at this time the output signal phase is 0, which should satisfy:

[0082] ;

[0083] Known The linear trend phase of the system is a discrete linear function. Two points determine a straight line, and a continuous linear function is obtained. Substituting it into the discrete frequency points of the frequency sweep, we can get Offline function, and then subtract the original phase-frequency curve The system linear trend phase is sufficient.

[0084] .

[0085] S5, based on the phase shift amplification technology, generates artificially set ,as well as Corresponding 、 、 and , and generate a table.

[0086] S6, using the step S4 obtained 、 、 and , query the table to get the amplitude ratio of the phase-frequency characteristic .

[0087] S7, comparison of multiple groups of optical microwave interferometry ranging experiments and , select and The amplitude ratio of the phase-frequency characteristics in the closest set of experiments is taken as the optimal amplitude ratio, and the amplitude ratios of the phase-frequency characteristics in the remaining experiments are normalized to the selected optimal amplitude ratio to obtain the normalized phase-frequency characteristic curve.

[0088] S8, establishing a linear characterization model of phase shift and measured distance variation based on the phase shift amplification technology, and calculating the distance variation based on the center frequency of the phase-frequency characteristic curve in step S7.

[0089] The principle of optical microwave interferometry ranging experiment is as follows Figure 2 As shown, the RF modulation module transmits a fixed, high-bandwidth, swept-frequency RF signal. The RF signal from the tunable signal source is evenly distributed to the measurement link and the reference link through a 50 / 50 power splitter. In the measurement link, the high-bandwidth, swept-frequency RF signal is modulated into the optical signal emitted by the laser to create an optically-carried microwave RF signal. This optically-carried microwave signal is amplified by a fiber erbium-doped amplifier (FDA) to amplify the power of the optically-carried microwave signal to sufficient power to cause interference with the microwave power in the reference link, thus satisfying the amplitude adjustment requirements of the phase-shift amplification technique. The optically-carried microwave signal carrying the distance measurement variation is obtained and converted to a microwave signal by a photodetector before entering the 50 / 50 power splitter. The microwave signal, after passing through the microwave reference arm, undergoes power and amplitude adjustment through a tunable attenuator. It then enters the 50 / 50 power splitter along with the final microwave signal from the measurement link, generating optically-carried microwave interference. The RF measurement module then receives the RF signal, collects the optically-carried microwave interference signal, and extracts phase and amplitude information. The displacement change to be measured is obtained by demodulating the phase-frequency characteristics of the optically carried microwave interference signal using phase shift amplification technology.

[0090] In the measurement link, due to the change of physical quantities at different measurement distances under high resolution, the phase shift change in the final destructive interference in the phase shift amplification method changes. The optical microwave interference fringes are formed in the amplitude-frequency characteristics, and the amplitude in the measurement link is recorded as , the reference link amplitude configured with the tunable attenuator in the reference link is recorded as ,definition = , that is, the ratio of the optical path amplitude to the microwave path signal amplitude is used as its amplitude ratio, and by modulating different amplitude ratios Different modulation depths are achieved, and the interference fringe spectrum changes of the amplitude-frequency characteristics are used as a reference feature for modulation depth normalization; at the same time, the phase shift changes in the phase-frequency characteristics are analyzed, which is also used as a reference feature for modulation depth normalization.

[0091] The present invention first collects original data from the experiment. Figure 2 The system shown is used to perform the original microwave interference ranging experiment. After the microwave interference, the microwave signal is collected by the radio frequency measurement module, and its amplitude-frequency characteristic data and phase-frequency characteristic data are extracted and processed respectively.

[0092] After completing the data acquisition of optical microwave interference, a set of amplitude-frequency characteristic data and phase-frequency characteristic data are obtained, such as Figure 3 and Figure 4 shown.

[0093] In the analysis of amplitude-frequency characteristic data, firstly according to the maximum and minimum power ratio Extract the amplitude ratio feature and conduct comparative analysis of the image. The two parts of the equation can be solved by the maximum and minimum power ratio. ; That is, the equation has two roots, and according to Figure 5-Figure 7 , regarding the phase-frequency characteristic morphology analysis under different amplitude ratios, we can eliminate one solution characteristic quantity, and finally obtain .

[0094] In the phase-frequency characteristic data analysis, due to To avoid the influence of phase wrapping, we first perform phase unwrapping to eliminate the Periodic characteristics, and then eliminate the system linear trend phase.

[0095] Combined with the tabulation method, specifically, under the ideal model of phase shift amplification technology, by artificially setting , and get the corresponding , , , Tabulation parameters, where , It is the normalized parameter corresponding to the frequency of minimum and maximum phase.

[0096] The image and data analysis of the pre-processed phase-frequency characteristic data are performed to obtain the phase-frequency characteristics of the experimental data obtained by the local maximum and minimum values. , The corresponding frequency is determined by , Combined with the previous table, the amplitude ratio of the phase-frequency characteristic is obtained by the table lookup method. .

[0097] Through the data analysis of the above amplitude-frequency characteristics and phase-frequency characteristics, an amplitude ratio is obtained. The two methods each measure an amplitude ratio. When the signal-to-noise ratio is relatively high, It is quite close, so normalize them all to this amplitude ratio.

[0098] Finally, the principle of phase shift amplification technology is used to establish a linear characterization model of phase shift and measurement distance change to achieve high-precision distance measurement sensing.

[0099] Specifically, step S2 includes the following steps:

[0100] S2.1, assuming that the two RF signals are and :

[0101] ;

[0102] in, and Respectively and The initial phase of represents the angular frequency, To measure the amplitude in the link, is the reference link amplitude.

[0103] S2.2, after the two signals are superimposed, the synthesized signal for:

[0104] ;

[0105] Among them, the composite phase of the signal Expressed as:

[0106] .

[0107] Composite amplitude of superimposed signals Expressed as:

[0108] ;

[0109] = ;

[0110] in, For phase.

[0111] S2.3, according to the amplitude-frequency characteristic curve, find the corresponding maximum and minimum power points within a cycle. The power reaches its maximum value when The maximum-minimum power ratio is :

[0112] ;

[0113] After simplification, we have:

[0114] .

[0115] Arrange both sides of the equation and solve it using the phase-frequency characteristic curve :

[0116] .

[0117] Solve the quadratic equation. From the root discriminant and the root-finding formula, we know that the equation has two solution characteristics. .

[0118] Depend on Figure 3 It can be seen that in the received signal of this experiment, its amplitude-frequency curve has two pairs of maximum points. Two different sets of amplitude ratios are obtained through the two sets of maximum point data. At this time, selection is made according to the phase-frequency curve. Each group will have two solutions for the amplitude ratio. According to the Vieta theorem, the solution of the equation is symmetrical about the value 1, that is, the amplitude ratio is either greater than or less than 1. It is eliminated according to the phase-frequency characteristic curve because the phase-frequency characteristic curve presents different morphological characteristics under different amplitude ratios. Figure 5-Figure 7 It can be seen that when the amplitude ratio is greater than 1, the curve shows a downward trend in the destructive interference region; when the amplitude ratio is less than 1, the curve shows an upward trend in the destructive interference region.

[0119] according to Figure 5-Figure 7 It can be seen that for the morphological analysis of phase-frequency characteristic images under different amplitude ratios, one solution feature quantity can be excluded Finally, under the amplitude-frequency characteristic analysis, a characteristic quantity is obtained .

[0120] Specifically, after obtaining the normalized 0-point symmetrical phase-frequency curve, the amplitude ratio is accurately approximated by using the table lookup method when determining the amplitude ratio. Figure 4 It can be seen that the steeper the slope shape determined by the maximum and minimum values, that is, the larger the slope, the closer the amplitude ratio is to 1. Therefore, the table lookup method determines the interval range in the table according to its slope value and selects the amplitude ratio value for each experiment. Step S3 is specifically as follows:

[0121] ;

[0122] ;

[0123] in, is the angular frequency, is the rough optical path difference, is the speed of light, is the center frequency of the phase-frequency characteristic curve, The free spectral range is the envelope between the two longitudinal modes with higher visibility in the amplitude-frequency characteristics, that is, the frequency range between the two positions marked in Figure 10 is the FSR. Frequency normalized parameters.

[0124] The solution is used to extract the symmetrical midpoint of the curve from the amplitude-frequency curve. The symmetrical midpoint of the curve is the destructive interference area, that is, the destructive interference area. In the same experiment, the phase-frequency curve and the amplitude-frequency curve are taken at the same frequency point to obtain the corresponding destructive interference area, and thus the solution is calculated. ,Establish and The normalized correspondence between .

[0125] Specifically, step S4 is as follows:

[0126] Obtaining the local minimum value based on the phase-frequency characteristic curve and maximum value , and calculate the local minimum and maximum value Corresponding , .

[0127] In actual experimental conditions, the down slope of the phase frequency maximum and minimum values ​​under different experiments under one fluctuation is as follows: Figure 11 shown.

[0128] Specifically, the table generated in step S5 is shown in Table 1.

[0129] Table 1 Maximum and minimum values ​​corresponding to the artificially generated amplitude ratios

[0130]

[0131] Among them, the phase maximum and minimum values ​​obtained in the experiment and the slope determined by the frequency-normalized parameters are matched with the phase maximum and minimum values ​​in the generated table and the slope determined by the corresponding frequency-normalized parameters. The best matching slope value is selected and the amplitude ratio corresponding to the slope in the table is located to complete the table lookup process.

[0132] Specifically, the normalization processing formula in step S7 is:

[0133] ;

[0134] in, is the optimal amplitude ratio selected, is the amplitude ratio to be normalized, is the phase to be normalized, is the normalized phase.

[0135] The normalized phase-frequency characteristic diagram is as follows: Figure 12 As shown by Figure 12 Obtain the center frequency of the phase-frequency characteristic curve corresponding to the normalized phase .

[0136] Specifically, step S8 is as follows:

[0137] ;

[0138] ;

[0139] in, is the distance change, is the phase difference.

[0140] therefore, It is the key to amplifying tiny distance changes and achieving ultra-high precision ranging.

[0141] The present invention proposes a modulation depth normalization method based on the joint analysis of amplitude-frequency characteristics and phase-frequency characteristics, which can effectively eliminate the amplitude ratio change problem caused by system power fluctuations, thereby meeting the stringent requirements of optical radio frequency phase-shift amplification technology for a fixed amplitude ratio. By extracting and horizontally comparing the amplitude-frequency and phase-frequency characteristics of each set of experimental data, the amplitude ratio with the smallest error is selected as the benchmark, and the modulation depth under different experiments is further normalized, so that all experimental results are subjected to phase-shift amplification and demodulation processing under the same gain conditions. This method significantly improves the system's phase demodulation accuracy and the measurement consistency of displacement changes, reduces the impact of system errors on detection results, enhances the system's practicality and stability, and has high engineering application value.

[0142] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A method for normalizing the phase shift amplification modulation depth of an optical microwave interferometric ranging system, characterized in that: The specific steps include: S1, collects the original data of microwave signals from the optical microwave interferometry ranging experiment, and extracts the amplitude-frequency characteristic data and phase-frequency characteristic data respectively; S2, in the amplitude-frequency characteristic data analysis, according to the maximum and minimum power ratio , and combined with image comparison analysis, the amplitude ratio of the amplitude-frequency characteristic is obtained ; S3, normalize the frequency; S4, in the phase-frequency characteristic data analysis, first phase unwrapping is performed to eliminate the 2π periodic characteristics, then the linear trend phase of the system is eliminated, and the local minimum is obtained according to the phase-frequency characteristic curve. and maximum value , and calculate the local minimum and maximum value The corresponding normalized parameters , ; S5, based on the phase shift amplification technology, generates artificially set ,as well as Corresponding 、 、 and , and generate a table; S6, using the step S4 obtained 、 、 and , query the table to get the amplitude ratio of the phase-frequency characteristic ; S7, comparison of multiple groups of optical microwave interferometry ranging experiments and , select and The amplitude ratio of the phase-frequency characteristics in the closest set of experiments is taken as the optimal amplitude ratio, and the amplitude ratios of the phase-frequency characteristics in the remaining experiments are normalized to the selected optimal amplitude ratio to obtain the normalized phase-frequency characteristic curve; S8, establishing a linear characterization model of phase shift and measured distance variation based on the phase shift amplification technology, and calculating the distance variation based on the center frequency of the phase-frequency characteristic curve in step S7.

2. The method for normalizing the phase shift amplification modulation depth of an optical microwave interferometer ranging system according to claim 1, characterized in that: Step S2 specifically includes the following steps: S2.1, assuming that the two RF signals are and : ； in, and Respectively and The initial phase of represents the angular frequency, To measure the amplitude in the link, is the reference link amplitude; S2.2, after the two signals are superimposed, the synthesized signal for: ； Among them, the composite phase of the signal Expressed as: ； Composite amplitude of superimposed signals Expressed as: ； = ； in, is the phase; S2.3, according to the amplitude-frequency characteristic curve, find the corresponding maximum and minimum power points within a cycle. The power reaches its maximum value when The maximum-minimum power ratio is : ； After simplification, we have: ； Arrange both sides of the equation and solve it using the phase-frequency characteristic curve : 。 3. The method for normalizing the phase shift amplification modulation depth of an optical microwave interferometer ranging system according to claim 1, characterized in that: Step S3 is specifically as follows: ； ； in, is the angular frequency, is the rough optical path difference, is the speed of light, is the center frequency of the phase-frequency characteristic curve, is the free spectral range, Frequency normalized parameters.

4. The method for normalizing the phase shift amplification modulation depth of an optical microwave interferometer ranging system according to claim 1, characterized in that: Step S4 is specifically as follows: Obtaining the local minimum value based on the phase-frequency characteristic curve and maximum value , and calculate the local minimum and maximum value Corresponding , .

5. The method for normalizing the phase shift amplification modulation depth of an optical microwave interferometer ranging system according to claim 1, characterized in that: The normalization processing formula in step S7 is: ； in, is the optimal amplitude ratio selected, is the amplitude ratio to be normalized, is the phase to be normalized, is the normalized phase, For RF signals The initial phase of is the frequency normalized parameter.

6. The method for normalizing the phase shift amplification modulation depth of an optical microwave interferometer ranging system according to claim 1, characterized in that: Step S8 is specifically as follows: ； ； in, is the distance change, is the phase difference, is the speed of light, is the center frequency of the phase-frequency characteristic curve.

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