Radar ranging method and system based on combination of coherent internal difference and microwave depth phase modulation

Abstract

The embodiment of the invention discloses a radar ranging method and system based on coherent internal difference and microwave depth phase modulation. A signal source is utilized to generate a radio frequency signal, the radio frequency signal is divided into two paths, and one path is sent; performing frequency mixing on the other path of radio frequency signal and the receiving signal to obtain a frequency mixing signal; preprocessing the frequency mixing signal, performing error correction after preprocessing to obtain a frequency mixing signal after error correction, and calculating amplitude frequency spectrum information; setting a target function for expressing the difference between the theoretical model of the numerical features of the ranging parameters and the predicted values of the ranging parameters; taking the minimization of the target function as a learning target, carrying out multiple times of iterative fitting on the distance measurement parameters until the target function converges, and obtaining the distance measurement parameters when the target function converges; and calculating distance information and displacement information of the target by using the distance measurement parameters. According to the invention, frequency modulation is carried out on a single frequency source, and high-precision distance measurement and displacement detection can be realized through a simple transmit-receive antenna and amplification, frequency mixing, filtering and post-processing algorithms.

Description

Technical Field

[0001] The present application relates to the field of radio frequency radar ranging technology, and in particular to a radar ranging method and system combining coherent interferometry with microwave deep phase modulation. Background Art

[0002] High-precision ranging and displacement detection technology is of great value in space orbit synchronization and ranging tasks, space exploration, drone landing guidance, radar feature extraction, Internet of Things communications, indoor positioning, extreme specific environment infrastructure health monitoring and safety warning. Phase-type laser radar has achieved millimeter-level to sub-millimeter-level distance measurement, and its distance resolution is high, but the system is more complex and the ranging cost is high, and it is easily affected by active interference. Compared with laser ranging technology, microwave radio frequency ranging and displacement detection solutions have stronger penetration capabilities, which can achieve more highly integrated and lower-cost ranging.

[0003] Currently, the ranging technologies based on microwave radio frequency (oscillation frequency in the range of 3kHz-300GHz) include ultra-wideband ranging, signal strength indication ranging, linear frequency modulation continuous wave radar ranging and difference frequency phase ranging.

[0004] Ultra-wideband ranging technology achieves ranging goals by transmitting and receiving two ultra-short pulse signals and calculating the signal transmission time. This solution has certain real-time positioning and communication capabilities and supports two-way communication. Its non-overlapping pulse signal modulation method gives it certain anti-interference capabilities. Its ranging accuracy is in the centimeter level, but ultra-wideband positioning and ranging require the deployment of a fixed positioning network, which has high deployment costs; its penetration is not as good as wireless communication technologies such as Bluetooth and Wi-Fi.

[0005] The basic principle of ranging based on received signal strength indication (RSSI) is to estimate the strength of the received wireless signal or the distance between devices. Specifically, the receiver measures the energy strength of the received RF signal and calculates the distance between the transmitter and the receiver by combining the known transmission power and propagation factor. This solution does not require additional hardware support and can be developed based on existing wireless communication devices. For example, there are many related studies on RSSI ranging technology based on Bluetooth and RSSI ranging technology based on Wi-Fi. This strategy can achieve ranging accuracy of decimeters to meters within a short distance (within 15m), which is easy to deploy quickly and at a low cost. However, the ranging accuracy is limited. Practical applications need to consider a variety of environmental factors and signal attenuation models. The calculation process is complicated and long-distance ranging cannot be achieved.

[0006] Linear frequency modulated continuous wave radar ranging achieves high-precision and fast distance measurement by modulating a low-frequency signal on a high-frequency carrier and using a high-precision phase measurement method based on timing technology. This strategy is suitable for scenarios requiring large-scale and high-precision measurements, and can achieve ranging over a large range. Within a range of 1km, it can achieve a ranging accuracy of about centimeters within an average ranging time of about 0.02-0.03s. However, this solution is difficult to build and the post-processing solution is complex, and it has poor adaptability to complex environments in ranging applications.

[0007] The difference frequency phase measurement ranging technology uses the frequency difference between two or more signals for precise measurement. In high-precision RF ranging and displacement detection, this solution determines the distance or displacement by analyzing the phase difference between the signals. In ranging applications, by sending a reference signal of known frequency and beating it with the received echo signal to calculate the difference frequency, the phase difference information between the transmitted signal and the received signal is obtained, and then the distance is estimated more accurately. This solution can reduce errors caused by environmental factors such as temperature changes and electromagnetic interference to a certain extent, and improve measurement accuracy and stability. In application scenarios such as drone landing guidance systems and construction engineering installation measurements, the integration of difference frequency phase measurement technology can increase the ranging accuracy of RF signals from meters to decimeters. In displacement detection applications, the displacement of an object can be accurately measured by receiving the phase changes of the signal at different times. This solution has certain advantages in ranging scenarios that require high dynamic range and high test accuracy.

[0008] In summary, the above-mentioned ranging schemes in the prior art have their own advantages and disadvantages in terms of ranging range, ranging accuracy, cost, system anti-interference ability, etc. The overall ranging accuracy and distance resolution need to be improved urgently, and cannot meet the needs of large-scale, long-distance, high-precision, all-weather ranging and displacement detection. Summary of the invention

[0009] The present application provides a radar ranging method and device combining coherent interferometry with microwave deep phase modulation to improve the ranging accuracy and resolution of coherent phase radio frequency ranging technology. The specific scheme is as follows:

[0010] In a first aspect, the present application provides a radar ranging method combining coherent interferometry with microwave deep phase modulation, comprising:

[0011] Generate a deep phase modulated radio frequency signal using a signal source, and divide the radio frequency signal into two paths and send one of them;

[0012] receiving a received signal reflected by a radio frequency signal received by the target, and mixing another radio frequency signal with the received signal to obtain a mixed signal;

[0013] Preprocessing the mixed signal, and performing error correction after the preprocessing to obtain an error-corrected mixed signal;

[0014] Calculating the amplitude-frequency spectrum information of the error-corrected mixed signal;

[0015] Setting an objective function for the difference between a theoretical model used to describe the numerical characteristics of a ranging parameter and a predicted value of the ranging parameter;

[0016] Taking minimizing the objective function as a learning goal, performing multiple iterative fitting on the ranging parameters, obtaining multi-order spectrum information by using the ranging parameters in the fitting process, and reducing the difference between the multi-order spectrum information and the amplitude spectrum information until the objective function converges, and obtaining the ranging parameters when the objective function converges, wherein the ranging parameters include the specific value of the phase to be measured;

[0017] The specific value of the phase to be measured when the objective function converges is used to calculate the distance information and displacement information of the target.

[0018] In a second aspect, the present application provides a radar ranging system combining coherent interferometry with microwave deep phase modulation, comprising:

[0019] A signal source, used for generating a deep phase modulated radio frequency signal;

[0020] A transmitting end, used for dividing the radio frequency signal into two paths and transmitting one of the two paths;

[0021] A receiving end is used to receive a reception signal reflected by a radio frequency signal received by the target, and mix another radio frequency signal with the reception signal to obtain a mixed signal;

[0022] The processing end is used to preprocess the mixing signal, and perform error correction after the preprocessing to obtain the error-corrected mixing signal; calculate the amplitude-frequency spectrum information of the error-corrected mixing signal; set the objective function of the difference between the theoretical model used to describe the numerical characteristics of the ranging parameter and the predicted value of the ranging parameter; take minimizing the objective function as the learning goal, perform multiple iterations of fitting on the ranging parameter, use the ranging parameter to calculate and obtain multi-order frequency spectrum information during the fitting process, and obtain the ranging parameter when the objective function converges by reducing the difference between the multi-order frequency spectrum information and the amplitude-frequency spectrum information until the objective function converges, and the ranging parameter includes the specific value of the phase to be measured; use the specific value of the phase to be measured when the objective function converges to calculate the distance information and displacement information of the target.

[0023] The innovative features of the embodiments of the present application include:

[0024] The embodiment of the present application discloses a radar ranging method and system combining coherent interferometry with microwave deep phase modulation, which uses a signal source to generate a radio frequency signal, and divides the radio frequency signal into two paths and sends one of the paths; receives a received signal reflected by one radio frequency signal received by a target, and mixes the other radio frequency signal with the received signal to obtain a mixed signal; preprocesses the mixed signal, and performs error correction after preprocessing to obtain an error-corrected mixed signal; calculates the amplitude-frequency spectrum information of the error-corrected mixed signal; sets an objective function of the difference between a theoretical model for describing the numerical characteristics of a ranging parameter and a predicted value of the ranging parameter; takes minimizing the objective function as a learning objective, performs multiple iterative fitting on the ranging parameter, obtains multi-order frequency spectrum information by using the ranging parameter calculation during the fitting process, and obtains the ranging parameter when the objective function converges by reducing the difference between the multi-order frequency spectrum information and the amplitude-frequency spectrum information until the objective function converges; and calculates the distance information and displacement information of the target by using the specific value of the phase to be measured when the objective function converges. The present application performs frequency modulation on a single frequency source, divides it into two paths and sends one of the RF signals, and through simple transceiver antennas and amplification, mixing, filtering and post-processing algorithms, can achieve high-precision distance measurement and displacement detection with an accuracy better than 0.05mm, thereby improving the ranging accuracy and resolution of the coherent phase measurement frequency modulated RF ranging technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art description are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work.

[0026] Figure 1 This is a schematic diagram of the overall architecture of the radio frequency interference ranging system;

[0027] Figure 2 A schematic flow chart of a radar ranging method combining coherent interferometry and microwave deep phase modulation provided in an embodiment of the present application;

[0028] Figure 3 A schematic diagram of the structure of a radar ranging system combining coherent interferon and microwave deep phase modulation provided in an embodiment of the present application. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] It should be noted that the terms "including" and "having" and any variations thereof in the embodiments of the present application and the accompanying drawings are intended to cover non-exclusive inclusions. For example, a process, method, device, product or equipment comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to these processes, methods, products or equipment.

[0031] Compared with ranging technology based on laser or optical signals, ranging and displacement monitoring technology based on radio frequency has the advantages of being able to work all-weather, having stronger penetration ability, strong non-line-of-sight ranging ability, wide coverage, simple system and low cost, etc. This application is committed to solving the problem that radio frequency ranging technology cannot meet the requirements of high precision, high resolution, all-weather, long distance and low power consumption, and discloses a radar ranging method and system combining coherent interferometry with microwave deep phase modulation.

[0032] The embodiment of the present application discloses a radar ranging method combining coherent intradyne and microwave deep phase modulation, which uses a signal source to generate a radio frequency signal, and divides the radio frequency signal into two paths and sends one of the paths; receives a received signal reflected by one radio frequency signal received by a target, and mixes the other radio frequency signal with the received signal to obtain a mixed signal; pre-processes the mixed signal, and performs error correction after the pre-processing to obtain an error-corrected mixed signal; calculates the amplitude-frequency spectrum information of the error-corrected mixed signal; sets an objective function for the difference between a theoretical model for describing the numerical characteristics of a ranging parameter and a predicted value of the ranging parameter; and takes minimizing the objective function as a learning objective. The objective function is converged, and the ranging parameters are iteratively fitted for multiple times. In the fitting process, the ranging parameters are used to calculate the multi-order spectrum information, and the difference between the multi-order spectrum information and the amplitude spectrum information is reduced until the objective function converges, so as to obtain the ranging parameters when the objective function converges. The present application performs frequency modulation on a single frequency source, divides it into two paths and sends one of the radio frequency signals, and realizes high-precision distance measurement and displacement detection with an accuracy better than 0.05 mm through simple transceiver antennas and amplification, mixing, filtering and post-processing algorithms, thereby improving the ranging accuracy and resolution of the coherent phase measurement frequency modulated radio frequency ranging technology, and improving the adaptability of ranging solutions under different application requirements.

[0033] The embodiments of the present application are described in detail below.

[0034] The present application provides a radar ranging method combining coherent interferometry with microwave deep phase modulation, which is implemented in a radio frequency interferometry ranging system. Figure 1 , Figure 1 It is a schematic diagram of the overall architecture of the radio frequency interference ranging system. The core components of the interference ranging system developed in this application are a signal generator that can realize the frequency modulation function, a directional transceiver antenna, and a receiving end signal processing device. The signal source transmits a deep phase modulated signal, and the signal is divided into two paths through a power divider, one as the transmitting signal of the transmitting antenna, and the other for mixing. The antenna transmits the radio frequency signal, and after free space transmission, the signal is reflected by the corner reflector. The present application covers two situations, one is that the transmitting and receiving antennas are on the same side, and the corner reflector reflects the signal back, and the other is that the transmitting and receiving antennas are on different sides, and the signal is reflected back by the corner reflector, and then received by the receiving end antenna, and the signal is amplified by an active low noise amplifier. The other signal output by the power divider is mixed with the amplified received signal to obtain a deep phase modulated received signal for post-processing.

[0035] The present application adopts the principle similar to homodyne interferometer to design the high-precision radio frequency ranging system. The core principle of the system is to accurately measure the phase difference between the transmitted and received signals and convert the phase difference information into time of arrival (TOA) information.

[0036] Assuming the frequency of the baseband RF signal is, for the coherent RF signal ranging system, the signal transmitted by the transmitting antenna at the transmitting end is

[0037]

[0038] Among them A t is the amplitude of the transmitted signal, is the initial phase of the signal source, the signal is an IQ quadrature signal, and f0 is the base frequency.

[0039] If the transmission distance of the radio signal is ΔL (the distance between the transmitting antenna and the receiving antenna, or the distance from the transmitting antenna to the reflecting surface plus the distance from the reflecting surface to the receiving antenna), the transmission delay of the transmission path is

[0040]

[0041] Where c is the speed of light. Then the signal at the receiving end is:

[0042]

[0043] Among them A r is the amplitude of the received signal, It is a constant transmission phase delay caused by non-self-space transmission paths (such as RF devices and connecting coaxial cables).

[0044] The coherent signal can be obtained by multiplying the complex conjugate of the transmitted signal and the received signal (down conversion through mixing), and then passing through a low-pass filter. The coherent signal can be expressed as:

[0045]

[0046] By processing the signal, the change in the phase difference between the received signal and the transmitted signal can be measured, thereby obtaining the change in the transmission signal delay, and then determining the change in the distance to be measured, and realizing the measurement of the target displacement. However, in practical applications, this single-frequency signal model is too simple and is subject to greater noise interference during channel transmission, which limits the measurement accuracy and resolution. Therefore, this application proposes a deep phase modulation (DPM) method to modulate the transmitted signal in order to obtain higher accuracy and resolution.

[0047] Figure 2 The present application provides a radar ranging method using coherent interferometry combined with microwave deep phase modulation, including:

[0048] S1, using a signal source to generate a deep phase modulated RF signal, and dividing the RF signal into two paths and sending one of them; in this step, the frequency of the signal source is sinusoidally modulated to obtain an output frequency; the output phase of the output signal of the signal source is determined using the output frequency; using the signal source to generate a deep phase modulated RF signal, wherein the frequency and phase of the RF signal are the output frequency and the output phase.

[0049] The appropriate frequency source RF signal modulation strategy can provide higher measurement accuracy and resolution potential for RF signals in the same frequency band. The output frequency is expressed as:

[0050]

[0051] Where f0 is the fundamental frequency, Δf represents the depth of frequency modulation, and f mod is the modulation frequency of the modulation signal, is the initial phase of the modulation signal, f DFM is the output frequency;

[0052] Then the phase of the output signal of the signal source is the output frequency f DFM The output phase is expressed as:

[0053]

[0054] Among them, φ out is the output phase, is the initial phase of the signal source, and i is the sign of the integral term.

[0055] The present application utilizes the frequency modulation function or phase modulation function of the signal generator to realize a phase modulated radio frequency signal in the form of formula (5).

[0056] Assuming that the transmission delay is τ, the phase of the received signal is expressed as:

[0057]

[0058] Among them, φ r is the phase of the received signal, τ is the transmission delay, and t is the signal time.

[0059] S2, receiving a reception signal reflected by a radio frequency signal received by the target, and mixing another radio frequency signal with the reception signal to obtain a mixed signal;

[0060] In this step, the phase of another RF signal is mixed with the phase of the received signal to obtain a mixing phase of the mixed signal, which is expressed as:

[0061]

[0062] Among them, φ mix is the mixing phase;

[0063] The mixing phase is subjected to basic constraints, frequency modulation range constraints and modulation depth constraints to obtain a mixing signal. When 2πf mod When τ<0.05, there is approximately sin(2πf mod τ)≈2πf mod τ and cos(2πf mod τ)≈1, then the mixing signal is expressed as:

[0064]

[0065] Where A is the signal amplitude.

[0066] The parameter representing the modulation depth is m = 2πΔfτ. When m is large enough, the mixed signal has a frequency of f. m The harmonic signals of m and m are The amplitude of each harmonic in the mixed signal is expressed as:

[0067]

[0068] in, is the harmonic amplitude of the mixing signal, k is a constant related to the signal power, J n (m) is the Bessel coefficient, is the phase to be measured, n is the order;

[0069] By performing spectrum analysis on the mixing signal and fitting its harmonic amplitude, the modulation depth m and carrier phase can be obtained. And other information, thereby achieving higher resolution ranging.

[0070] For distance measurement at different distances, different modulation depths and different frequency bands, it is necessary to preliminarily estimate the mixed signal through program operation, and then post-process the mixed signal by adjusting the parameter m. n and Perform optimal fitting to obtain the basic constraints of the distance measurement displacement change information, so that sin(2πf mod τ)≈2πf mod τ and cos(2πf mod τ)≈1, then the basic constraint is expressed as:

[0071] 2πf mod τ<0.05 (11)

[0072] In addition, signal generators usually have frequency modulation range limitations. Taking the Keysight Technologies E8247 function signal generator as an example, its modulation depth and modulation frequency information must meet the frequency modulation range constraints. The frequency modulation range constraints are expressed as follows:

[0073]

[0074] The carrier phase solution accuracy is highly related to the modulation depth m, so the modulation depth constraint must be met. The modulation depth constraint is expressed by the formula:

[0075] m=2πΔfτ≥3 (13)

[0076] in, ΔL is the distance to be measured∈ r is the relative dielectric constant of air, c is the speed of light, and rad represents the unit of radians.

[0077] This application requires that the modulation parameters etc. be reasonably designed first to ensure the operation of the system.

[0078] S3, preprocessing the mixed signal, and performing error correction after the preprocessing to obtain an error-corrected mixed signal;

[0079] After the receiving end receives the antenna signal and mixes it with the transmitting antenna signal, a deep phase modulation signal can be obtained as shown in formula (9), and its spectrum diagram is shown in terms of fm It is a multiple harmonic signal of the fundamental frequency, and its harmonic amplitude is related to the distance-related physical quantity to be measured. It is highly correlated with m, so the distance-related information can be solved by fitting the measured harmonic amplitude with the ideal model through a numerical fitting algorithm.

[0080] As an optional implementation of the present application, S3 includes:

[0081] Performing analog-to-digital conversion, anti-aliasing and sampling on the mixing signal to obtain a mixing signal sequence x(t); the mixing signal is composed of n harmonics;

[0082] Wherein, the sampling frequency is set to an integer multiple of the modulation frequency of the modulation signal;

[0083] The mixing signal sequence is segmented according to the time series, and each segmented signal is subjected to a fast Fourier transform to obtain the complex amplitude value of each harmonic, which is expressed as:

[0084]

[0085] Among them, e inψ The n in the superscript inψ represents the order, ψ represents the modulation phase, and i is an imaginary number.

[0086] The amplitude deviation caused by sampling in the complex amplitude value of each harmonic is corrected to obtain an error-corrected mixed signal.

[0087] S4, calculating the amplitude-frequency spectrum information of the error-corrected mixed signal;

[0088] S5, setting an objective function for the difference between a theoretical model for describing the numerical characteristics of the ranging parameter and a predicted value of the ranging parameter;

[0089] In this step, the distance measurement parameters to be fitted are first determined; the first amplitude value is determined according to the distance measurement parameters to be fitted, and the second amplitude value is determined according to the amplitude spectrum information; and then the objective function representing the difference between the first amplitude value and the second amplitude value is constructed, which is expressed as:

[0090]

[0091] where χ 2 is the objective function, is the first amplitude value, is the second amplitude value.

[0092] S6, taking minimizing the objective function as a learning goal, performing multiple iterative fitting on the ranging parameters, obtaining multi-order spectrum information by using the ranging parameters in the fitting process, and reducing the difference between the multi-order spectrum information and the amplitude spectrum information until the objective function converges, and obtaining the ranging parameters when the objective function converges, wherein the ranging parameters include the specific value of the phase to be measured;

[0093] As an optional implementation of the present application, S6 includes:

[0094] S61, calculating each harmonic phase angle nψ in the error-corrected mixing signal using the harmonic complex amplitude spectrum, and performing phase unwrapping and linear fitting on the phase angle nψ to obtain an initial value of the modulation phase ψ;

[0095] S62, using the rough distance estimation information and the complex amplitude values ​​of the first and second harmonics to obtain the parameters m, k and Initial value of:

[0096] For the initial value of the modulation phase, the phase angle information nψ of each harmonic complex amplitude is first calculated, and then phase unwrap is performed and a simple linear fit is performed to obtain the predicted initial value ψ0; for the parameters m, k and The initial calculation uses the rough distance estimation information and the 1st and 2nd harmonic amplitude information for fitting, and the subsequent estimation can use the results of the previous stage as the initial value.

[0097] S63, applying the Levenberg-Marquardt algorithm to minimize the objective function as a learning goal, introducing the initial value of the modulation phase ψ, the parameters m, k and The initial value of the multi-order spectrum information of the ranging parameter is calculated in the fitting process, and the ranging parameter m is adjusted by reducing the difference between the multi-order spectrum information and the amplitude spectrum information. ψ, k are optimized for multiple cycles to obtain the ranging parameter m when the objective function reaches the convergence condition. ψ, k.

[0098] In this step, the Levenberg-Marquardt algorithm is used to minimize the objective function χ 2 , constantly adjust the parameter m, ψ, k, makes the fitted theoretical value and the measured value as close as possible, that is, the loss function is as small as possible. In addition, the impact of falling into the local optimal solution problem on the solution result can also be reduced by using individual optimization algorithms such as Genetic Algorithm, Tabu Search, hill climbing, Iterated Local Search, or population intelligent optimization algorithms.

[0099] The convergence condition is that the change of the objective function is less than a threshold value, and the value of the objective function is less than a given error tolerance.

[0100] This step checks whether the objective function converges. If the objective function change is less than a certain threshold and the value is less than a given error tolerance, it is considered to have converged and the final parameters are output. Otherwise, the parameters continue to be adjusted.

[0101] S7, using the specific value of the phase to be measured when the objective function converges, calculate the distance information and displacement information of the target.

[0102] In this step, the ranging parameter m is obtained. ψ, k can be used to obtain the final transmission delay. Multiplying the final transmission delay by the speed of light is the distance of the target. The change of distance in unit time is the displacement information of the target.

[0103] refer to Figure 3 The present application provides a radar ranging system combining coherent interferometry with microwave deep phase modulation, comprising:

[0104] A signal source 31, used to generate a deep phase modulated radio frequency signal;

[0105] A transmitting end 32, used for dividing the radio frequency signal into two paths and transmitting one of the two paths;

[0106] The receiving end 33 is used to receive a reception signal reflected by a radio frequency signal received by the target, and mix another radio frequency signal with the reception signal to obtain a mixed signal;

[0107] The processing end 34 is used to preprocess the mixing signal, and perform error correction after the preprocessing to obtain the error-corrected mixing signal; calculate the amplitude-frequency spectrum information of the error-corrected mixing signal; set the objective function of the difference between the theoretical model used to describe the numerical characteristics of the ranging parameter and the predicted value of the ranging parameter; with minimizing the objective function as the learning goal, perform multiple iterative fitting on the ranging parameter, and use the ranging parameter to calculate and obtain multi-order frequency spectrum information during the fitting process, and obtain the ranging parameter when the objective function converges by reducing the difference between the multi-order frequency spectrum information and the amplitude-frequency spectrum information until the objective function converges, and the ranging parameter includes the specific value of the phase to be measured; and use the specific value of the phase to be measured when the objective function converges to calculate the distance information and displacement information of the target.

[0108] Optionally, the receiving end 32 is specifically configured to:

[0109] The frequency of the signal source is sinusoidally modulated to obtain the output frequency;

[0110] Determine the output phase of the output signal of the signal source by using the output frequency;

[0111] The signal source is used to generate a deep phase modulated radio frequency signal, wherein the frequency and phase of the radio frequency signal are the output frequency and the output phase.

[0112] The processing end 34 is specifically used for:

[0113] Calculating each harmonic phase angle nψ in the error-corrected mixing signal using the harmonic complex amplitude spectrum, and performing phase unwrapping and linear fitting on the phase angle nψ to obtain an initial value of the modulation phase ψ;

[0114] The parameters m, k and The initial value of

[0115] The Levenberg-Marquardt algorithm is applied to minimize the objective function as the learning goal, and the initial value of the modulation phase ψ, the parameters m, k and The initial value of the multi-order spectrum information of the ranging parameter is calculated in the fitting process, and the ranging parameter m is adjusted by reducing the difference between the multi-order spectrum information and the amplitude spectrum information. ψ, k are optimized for multiple cycles to obtain the ranging parameter m when the objective function reaches the convergence condition. ψ, k.

[0116] The embodiment of the present application discloses a radar ranging system combining coherent interferometry with microwave deep phase modulation, which generates a radio frequency signal by a signal source, and the transmitting end divides the radio frequency signal into two paths and transmits one of the paths; the receiving end receives a received signal reflected by one radio frequency signal received by a target, and mixes the other radio frequency signal with the received signal to obtain a mixed signal; the processing end preprocesses the mixed signal, and performs error correction after the preprocessing to obtain an error-corrected mixed signal; the amplitude-frequency spectrum information of the error-corrected mixed signal is calculated; an objective function of the difference between a theoretical model for describing the numerical characteristics of a ranging parameter and a predicted value of the ranging parameter is set; with minimizing the objective function as a learning objective, the ranging parameter is iteratively fitted for multiple times, and multi-order frequency spectrum information is calculated using the ranging parameter during the fitting process, and the ranging parameter is obtained when the objective function converges by reducing the difference between the multi-order frequency spectrum information and the amplitude-frequency spectrum information until the objective function converges, and the ranging parameter includes the specific value of the phase to be measured; the distance information and displacement information of the target are calculated using the specific value of the phase to be measured when the objective function converges. The present application performs frequency modulation on a single frequency source, divides the signal into two paths and sends one of the RF signals, and realizes high-precision distance measurement and displacement detection with an accuracy better than 0.05 mm through simple transceiver antennas and amplification, mixing, filtering and post-processing algorithms, thereby improving the ranging accuracy and resolution of the coherent phase measurement frequency-modulated RF ranging technology, and improving the adaptability of ranging solutions under different application requirements.

[0117] Those skilled in the art can understand that the drawing is only a schematic diagram of an embodiment, and the modules or processes in the drawing are not necessarily required to implement the present application.

[0118] Those skilled in the art can understand that the modules in the device in the embodiment can be distributed in the device in the embodiment according to the description of the embodiment, or can be changed accordingly and located in one or more devices different from the embodiment. The modules in the above embodiment can be combined into one module, or can be further divided into multiple sub-modules.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A radar ranging method combining coherent interferometry with microwave deep phase modulation, characterized in that: include: Generate a deep phase modulated radio frequency signal using a signal source, and divide the radio frequency signal into two paths and send one of them; receiving a received signal reflected by a radio frequency signal received by the target, and mixing another radio frequency signal with the received signal to obtain a mixed signal; Preprocessing the mixed signal, and performing error correction after the preprocessing to obtain an error-corrected mixed signal; Calculating the amplitude-frequency spectrum information of the error-corrected mixed signal; Setting an objective function for the difference between a theoretical model used to describe the numerical characteristics of a ranging parameter and a predicted value of the ranging parameter; Taking minimizing the objective function as a learning goal, performing multiple iterations of fitting on the ranging parameters, obtaining multi-order spectrum information by using the ranging parameters in the fitting process, and reducing the difference between the multi-order spectrum information and the amplitude spectrum information until the objective function converges, and obtaining the ranging parameters when the objective function converges, wherein the ranging parameters include the specific value of the phase to be measured; The specific value of the phase to be measured when the objective function converges is used to calculate the distance information and displacement information of the target.

2. The radar ranging method of coherent interferometry combined with microwave deep phase modulation according to claim 1 is characterized in that: The method of generating a deep phase modulated radio frequency signal using a signal source comprises: The frequency of the signal source is sinusoidally modulated to obtain the output frequency; Determine the output phase of the output signal of the signal source by using the output frequency; The signal source is used to generate a deep phase modulated radio frequency signal, wherein the frequency and phase of the radio frequency signal are the output frequency and the output phase.

3. The radar ranging method of coherent interferometry combined with microwave deep phase modulation according to claim 2 is characterized in that: The output frequency is expressed as: Where f0 is the fundamental frequency, Δf represents the depth of frequency modulation, and f mod is the modulation frequency of the modulation signal, is the initial phase of the modulation signal, f DFM is the output frequency; The output phase is expressed as: Among them, φ out is the output phase, is the initial phase of the signal source, and i is the sign of the integral term.

4. The radar ranging method of coherent interferometry combined with microwave deep phase modulation according to claim 3 is characterized in that: The phase of the received signal is expressed as: Among them, φ r is the phase of the received signal, τ is the transmission delay, and t is the signal time.

5. The radar ranging method of coherent interferometry combined with microwave deep phase modulation according to claim 4 is characterized in that: The mixing of another RF signal with the received signal to obtain a mixed signal comprises: Another RF signal is mixed with the received signal to obtain a mixing phase of the mixed signal, which is expressed as: Among them, φ mix is the mixing phase; The mixing phase is subjected to basic constraints, frequency modulation range constraints and modulation depth constraints to obtain a mixing signal, which is expressed as: Where A is the signal amplitude; The amplitude of each harmonic in the mixed signal is expressed as: in, is the harmonic amplitude of the mixing signal, k is a constant related to the signal power, J n (m) is the Bessel coefficient, is the phase to be measured, n is the order; The basic constraint is expressed by the formula: 2πf mod τ<0.05 The frequency modulation range constraint is expressed as: The modulation depth constraint is formulated as: m=2πΔfτ≥3 in, ΔL is the distance to be measured∈ r is the relative dielectric constant of air, c is the speed of light, and rad represents the unit of radians.

6. The radar ranging method of coherent interferometry combined with microwave deep phase modulation according to claim 5 is characterized in that: Preprocessing the mixed signal, and performing error correction after the preprocessing to obtain an error-corrected mixed signal includes: Performing analog-to-digital conversion, anti-aliasing and sampling on the mixing signal to obtain a mixing signal sequence x(t); the mixing signal is composed of n harmonics; Wherein, the sampling frequency is set to an integer multiple of the modulation frequency of the modulation signal; The mixing signal sequence is segmented according to the time series, and each segmented signal is subjected to a fast Fourier transform to obtain the complex amplitude value of each harmonic, which is expressed as: Among them, e inψ In the superscript inψ, n indicates the order, ψ indicates the modulation phase, and i is an imaginary number; The amplitude deviation caused by the noise of the sampling device in the complex amplitude value of each harmonic is corrected to obtain an error-corrected mixed signal.

7. The radar ranging method of coherent interferometry combined with microwave deep phase modulation according to claim 6 is characterized in that: The objective function of setting the difference between the theoretical model for describing the numerical characteristics of the ranging parameter and the predicted value of the ranging parameter includes: Determine the ranging parameters to be fitted; Determine a first amplitude value according to the distance measurement parameter to be fitted, and determine a second amplitude value according to the amplitude spectrum information; Construct an objective function representing the difference between the first amplitude value and the second amplitude value, expressed as: where χ 2 is the objective function, is the first amplitude value, is the second amplitude value.

8. The radar ranging method of coherent interferometry combined with microwave deep phase modulation according to claim 7 is characterized in that: The objective function is minimized as the learning goal, and the ranging parameters are iteratively fitted multiple times. In the fitting process, the ranging parameters are used to calculate the multi-order spectrum information, and the difference between the multi-order spectrum information and the amplitude spectrum information is reduced until the objective function converges, and the ranging parameters when the objective function converges are obtained. The ranging parameters include the specific values ​​of the phase to be measured, including: Calculating each harmonic phase angle nψ in the error-corrected mixing signal using the harmonic complex amplitude spectrum, and performing phase unwrapping and linear fitting on the phase angle nψ to obtain an initial value of the modulation phase ψ; The parameters m, k and The initial value of The Levenberg-Marquardt algorithm is applied to minimize the objective function as the learning goal, and the initial value of the modulation phase ψ, the parameters m, k and The initial value of the multi-order spectrum information of the ranging parameter is calculated in the fitting process, and the ranging parameter m, is adjusted by reducing the difference between the multi-order spectrum information and the amplitude spectrum information. ψ,k is optimized for multiple cycles to obtain the ranging parameters m, ψ,k.

9. The radar ranging method of coherent interferometry combined with microwave deep phase modulation according to claim 7, characterized in that: The convergence condition is that the change of the objective function is less than a threshold value, and the value of the objective function is less than a given error tolerance.

10. A radar ranging system combining coherent interferometry and microwave deep phase modulation, characterized in that: include: A signal source, used for generating a deep phase modulated radio frequency signal; A transmitting end, used for dividing the radio frequency signal into two paths and transmitting one of the two paths; A receiving end is used to receive a reception signal reflected by a radio frequency signal received by the target, and mix another radio frequency signal with the reception signal to obtain a mixed signal; A processing end is used to preprocess the mixing signal, and perform error correction after the preprocessing to obtain an error-corrected mixing signal; and calculate the amplitude-frequency spectrum information of the error-corrected mixing signal; An objective function of the difference between a theoretical model for describing the numerical characteristics of a ranging parameter and a predicted value of the ranging parameter is set; the ranging parameter is iteratively fitted for multiple times with minimization of the objective function as a learning objective, multi-order spectrum information is calculated using the ranging parameter during the fitting process, and the ranging parameter when the objective function converges is obtained by reducing the difference between the multi-order spectrum information and the amplitude spectrum information until the objective function converges, wherein the ranging parameter includes a specific value of a phase to be measured; and the distance information and displacement information of the target are calculated using the specific value of the phase to be measured when the objective function converges.

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