Linear correction system and method based on Doppler compensation and storage medium

Abstract

The invention is suitable for the field of radar signal processing, and provides a linear system and method based on Doppler compensation and a storage medium, and the system comprises a scanning part which is used for irradiating a to-be-measured target with modulated laser emitted by a laser through an emission light path. And the receiving part is used for receiving the modulated laser generated by the distance measuring laser and receiving the reflected laser reflected by the target to be measured. And the correction part is used for obtaining correction laser according to the modulation laser and the reflection laser so as to correct the modulation laser of the scanning part. The linear correction method based on the system comprises the following steps: acquiring an initial correction triangular wave of the laser and original intermediate frequency signal data of a to-be-measured target; and converting the original intermediate frequency signal to a complex domain to obtain a complex domain intermediate frequency signal. And generating a linear correction parameter according to the complex field intermediate frequency signal so as to correct the laser. According to the scheme, the problem that an existing radar detection system is inaccurate in distance measurement is solved.

Description

Technical Field

[0001] This application belongs to the field of radar signal processing, and particularly relates to a linear system, method, and storage medium based on Doppler compensation. Background Art

[0002] A rotating mirror type FMCW (Frequency Modulated Continuous Wave) lidar is a lidar system that uses frequency modulated continuous wave technology. It measures the distance and speed of a target by modulating the frequency of the laser and measuring the frequency difference of the echo signal. Traditional lidar systems usually use pulsed lasers and measure the distance of the target by measuring the time difference of the laser pulses. While the FMCW lidar uses frequency modulated continuous wave technology and measures the distance and speed of the target by measuring the change in laser frequency. The rotating mirror type FMCW lidar scans the laser beam by rotating a reflecting mirror or a scanning mirror to obtain three-dimensional information of the target.

[0003] However, the movement of the rotating mirror in the rotating mirror type FMCW lidar will have an impact on the received echo signal in the form of Doppler frequency shift. Doppler frequency shift is caused by the movement of the target. When the laser beam scans a moving target, the frequency of the reflected light on the target will change, resulting in Doppler frequency shift in the received echo signal. Therefore, how to reduce the impact of Doppler frequency shift on the received signal and improve the measurement accuracy and speed is of crucial importance. Summary of the Invention

[0004] The purpose of this application is to provide a linear correction system, method, and terminal device based on Doppler compensation, aiming to solve the problem of inaccurate distance measurement in existing devices.

[0005] The first aspect of the embodiments of this application provides a linear correction system based on Doppler compensation, including:

[0006] A scanning component 201, including a laser, and the scanning component is used to irradiate the modulated laser emitted by the laser to a target to be measured through an emission optical path;

[0007] A receiving component 202, configured to receive the modulated laser generated by the ranging laser, and receive the reflected laser reflected by the target to be measured;

[0008] A correction component 203, coupled to the receiving component and the scanning component, is configured to obtain a correction laser based on the modulated laser and the reflected laser to correct the modulated laser of the scanning component; wherein, the correction component is specifically configured to perform analog-to-digital conversion on the modulated laser and the reflected laser to obtain an initial correction triangular wave and original intermediate-frequency signal data of a target to be measured, then convert the original intermediate-frequency signal to the complex domain to obtain a complex-domain intermediate-frequency signal; and finally generate a linear correction parameter according to the complex-domain intermediate-frequency signal to correct the laser.

[0009] In an alternative embodiment, the correction component includes an analog-to-digital converter and a digital signal processor. The analog-to-digital converter is coupled to the detector and is configured to convert a detected optical wave signal into a digital signal;

[0010] The digital signal processor is configured to generate the correction laser according to the digital signal.

[0011] In an alternative embodiment, the scanning component includes:

[0012] A laser, which generates the modulated laser;

[0013] A beam splitter, configured to divide the modulated laser into two paths; a circulator, which receives one path of the modulated laser and outputs the modulated laser along a first output optical path, and a to-be-range-measured target is disposed on the first output optical path; the first output optical path is the transmitting optical path;

[0014] A motor scanning device, disposed on the first output optical path and located between the to-be-range-measured target and the circulator, and the motor scanning device is rotatable.

[0015] In an alternative embodiment, the receiving component includes:

[0016] A coupler, coupled to a second output optical path of the circulator and coupled to the other optical path of the beam splitter;

[0017] A detector, an incident optical path of the detector is coupled to an output optical path of the coupler, and outputs the modulated laser and the reflected laser to the correction component.

[0018] In an alternative embodiment, the system further includes: a collimator, disposed on the first output optical path and located between the circulator and the motor scanner.

[0019] A second aspect of the embodiments of the present application provides a linear correction method based on Doppler compensation. The method includes:

[0020] Obtain an initial correction triangular wave of the laser and original intermediate-frequency signal data of a target to be measured;

[0021] Convert the original intermediate frequency signal to the complex domain to obtain an intermediate frequency signal in the complex domain;

[0022] Generate a linear correction parameter according to the intermediate frequency signal in the complex domain to correct the laser.

[0023] In an alternative embodiment, the converting the original intermediate frequency signal to the complex domain to obtain an intermediate frequency signal in the complex domain includes:

[0024] Perform a Hilbert transform on the original intermediate frequency signal data to convert the original intermediate frequency signal to the complex domain to obtain an intermediate frequency signal in the complex domain.

[0025] In an alternative embodiment, the generating a linear correction parameter according to the intermediate frequency signal in the complex domain includes:

[0026] Perform a phase calculation on the intermediate frequency signal in the complex domain to obtain a phase sequence;

[0027] Calculate the time-frequency curve of the intermediate frequency data according to the sampling frequency and the phase sequence;

[0028] Perform a fluctuation analysis on the time-frequency curve. If the fluctuation amount is lower than a preset standard deviation, the correction parameter is the parameter of the initial correction triangular wave;

[0029] If the volatility is higher than the standard deviation, update the correction parameter according to the characteristics of the time-frequency curve.

[0030] In an alternative embodiment, the updating the correction parameter according to the characteristics of the time-frequency curve includes:

[0031] Analyze the characteristics of the time-frequency curve to generate a Doppler frequency shift result;

[0032] Update the correction parameter according to the Doppler frequency shift result.

[0033] A fourth aspect of the embodiments of the present application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method described in the second aspect above is implemented.

[0034] Beneficial effects of the present application

[0035] By using a Doppler compensation linear correction method provided by the present application, the original intermediate frequency signal is converted to the complex domain to obtain a complex intermediate frequency signal, and then the laser is corrected according to the linear correction parameter generated from the complex intermediate frequency signal to solve the problem of inaccurate ranging. Description of the Drawings

[0036] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0037] Figure 1 It is a schematic structural diagram of an existing radar monitoring system;

[0038] Figure 2 It is a module diagram of a linear correction system based on Doppler compensation provided by an embodiment of the present application;

[0039] Figure 3 It is a module diagram of a correction component provided by an embodiment of the present application;

[0040] Figure 4 It is a module diagram of a scanning component provided by an embodiment of the present application;

[0041] Figure 5 It is a module diagram of a receiving component provided by an embodiment of the present application;

[0042] Figure 6 It is a schematic structural diagram of the system provided by an embodiment of the present application;

[0043] Figure 7 It is a schematic flow diagram of a linear correction method based on Doppler compensation provided by an embodiment of the present application;

[0044] Figure 8 It is a schematic flow diagram of generating linear correction parameters according to the intermediate frequency signal in the complex domain provided by an embodiment of the present application;

[0045] Figure 9 It is a schematic flow diagram of updating correction parameters according to the characteristics of the time-frequency curve provided by an embodiment of the present application;

[0046] Figure 10 It is a schematic structural diagram of a terminal device provided by an embodiment of the present application. Detailed implementation manners

[0047] In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also be implemented in other embodiments without these specific details. In other cases, the detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present application.

[0048] It should be understood that, as used in the specification of this application and the appended claims, the term "comprising" indicates the presence of the described features, integers, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or their combinations.

[0049] It should also be understood that the term "and / or" as used in the specification of this application and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0050] As used in the specification of this application and the appended claims, the term "if" may be construed, depending on the context, as "when", "once", "in response to determining", or "in response to detecting". Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be construed, depending on the context, as meaning "once determined", "in response to determining", "once [the described condition or event] is detected", or "in response to detecting [the described condition or event]".

[0051] In addition, in the description of the specification of this application and the appended claims, the terms "first", "second", "third", etc. are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0052] Reference to "one embodiment" or "some embodiments" or the like described in the specification of this application means that a particular feature, structure or characteristic described in connection with that embodiment is included in one or more embodiments of this application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized.

[0053] It should be understood that the magnitudes of the sequence numbers of the steps in this embodiment do not mean the order of execution is prior or subsequent. The order of execution of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of this application.

[0054] Figure 1This is an existing FMCW lidar system. In a FMCW lidar system based on a rotating mirror, the movement of the rotating mirror will cause the Doppler effect, which will seriously affect the ranging accuracy and the accuracy of speed measurement. To solve this problem, existing calibration methods usually use light rays or static spatial points, select a fixed distance to calibrate the modulation parameters, so as to ensure the linearity and accuracy of static ranging.

[0055] Under this background, in order to cope with the influence of the Doppler effect caused by the movement of the rotating mirror on the ranging and speed measurement of the FMCW lidar system, a calibration method needs to be developed. This calibration method needs to be able to identify and compensate for the Doppler frequency shift caused by the movement of the rotating mirror, so as to ensure the ranging accuracy and the accuracy of speed measurement. This calibration method can be based on advanced signal processing algorithms and calibration techniques, and use known static distance points or optical calibration references to calibrate the modulation parameters of the lidar system, so as to eliminate the measurement errors caused by the Doppler effect.

[0056] The development of this background technology will provide important support for the performance improvement of the rotating mirror type FMCW lidar system, enabling it to more accurately achieve target distance measurement and speed measurement in practical applications. At the same time, the research and implementation of this calibration method will also promote related technologies in the fields of radar and optical measurement, and contribute to the development of the high-precision measurement field.

[0057] In order to illustrate the technical solution of the present application, specific embodiments will be described below.

[0058] Refer to Figure 2 , which shows a module diagram of a linear calibration system based on Doppler compensation provided by an embodiment of the present application.

[0059] The calibration system includes:

[0060] A scanning component 201, including a laser, and the scanning component is used to irradiate the modulated laser emitted by the laser to a target to be measured through a transmitting optical path;

[0061] A receiving component 202, which is used to receive the modulated laser generated by the ranging laser and the reflected laser reflected by the target to be measured;

[0062] A calibration component 203, which is coupled to the receiving component and the scanning component, and is used to obtain a calibration laser according to the modulated laser and the reflected laser, so as to calibrate the modulated laser of the scanning component; wherein, the calibration component is specifically used to perform analog-to-digital conversion on the modulated laser and the reflected laser to obtain an initial calibration triangular wave and the original intermediate frequency signal data of the target to be measured, and then convert the original intermediate frequency signal to the complex domain to obtain a complex domain intermediate frequency signal; finally, generate a linear calibration parameter according to the complex domain intermediate frequency signal to calibrate the laser.

[0063] Exemplarily, assume there is a lidar ranging system, which is used to measure the distance to the front obstacle, for example, in an autonomous vehicle or a robot. This system mainly includes three parts: a scanning component, a receiving component, and a calibration component.

[0064] Scanning component 201: It includes a laser that can emit modulated laser light. The laser light is directed through the emission optical path towards the target to be measured in the front, such as an obstacle.

[0065] The modulated laser light emitted by the laser may be a continuous or pulsed laser beam, whose frequency, amplitude, or phase can be modulated to carry information.

[0066] Receiving component 202: The receiving component has two main functions: one is to receive the modulated laser light generated by the ranging laser (as a reference signal), and the other is to receive the reflected laser light reflected from the target to be measured.

[0067] When the modulated laser light irradiates the obstacle, part of the laser light will be reflected back and captured by the receiving component. This reflected laser light contains the distance information of the obstacle because the propagation time of light is a function of the distance.

[0068] Calibration component 203: The calibration component 203 is connected to the receiving component 202 and the scanning component 201. Its task is to process the received modulated laser light and reflected laser light to calibrate the modulated laser light emitted by the scanning component 201.

[0069] First, the calibration component 203 will perform analog-to-digital conversion on the modulated laser light and the reflected laser light, converting them from analog signals to digital signals. This can facilitate subsequent digital signal processing.

[0070] After conversion, the calibration component 203 will obtain an initial calibration triangular wave and the original intermediate frequency signal data of the target to be measured. This intermediate frequency signal is the difference signal between the modulated laser light and the reflected laser light, and it contains the distance information of the obstacle.

[0071] Next, the calibration component 203 will convert this original intermediate frequency signal into the complex domain. In the complex domain, the processing and analysis of signals are usually easier and more intuitive.

[0072] Finally, based on the intermediate frequency signal in the complex domain, the calibration component 203 will generate linear calibration parameters. These parameters can be used to adjust the output of the laser to ensure that the modulated laser light emitted by it is accurate and reliable. For example, if the system detects that the frequency of the laser output has drifted, the calibration component 203 will generate a calibration parameter to adjust the frequency of the laser to keep it stable.

[0073] Through this process, the lidar ranging system can continuously self-correct to ensure the accuracy and stability of the measurement results, maintaining high performance even in the face of environmental changes or system aging.

[0074] Referring to Figure 3 , in an implementable embodiment of the present application, the correction component 203 includes: an analog-to-digital converter 301 and a digital signal processor 302;

[0075] The analog-to-digital converter 301 is coupled to the detector 206 and is used to convert the detected optical wave signal into a digital signal;

[0076] The digital signal processor 302 is used to generate a corrected modulation wave signal based on the digital signal.

[0077] Exemplarily, the correction component 203 is typically used in a lidar system to perform digital signal processing and correction on the optical wave signal received from the detector. Here is an example to illustrate the working process of the correction component 203:

[0078] Suppose there is a lidar system where the detector is responsible for receiving the optical wave signal reflected from the target object. The detector converts the optical wave signal into an analog electrical signal, and then the analog-to-digital converter 301 converts the analog electrical signal into a digital signal.

[0079] The digital signal processor 302 receives these digital signals and processes them according to preset algorithms and correction parameters to generate a corrected modulation wave signal. This processing process may include operations such as filtering, denoising, correction, and demodulation to ensure that the final modulation wave signal can accurately reflect information such as the distance and speed of the target object.

[0080] Specifically, assume that it is necessary to obtain the distance information of the target object based on the received optical wave signal. The digital signal processor can perform time-domain and frequency-domain analysis on the received digital signals, extract the echo signal characteristics of the target object, and correct these characteristics according to the correction parameters of the system, and finally generate an accurate modulation wave signal to provide the distance information of the target object.

[0081] In summary, the correction component 203 includes an analog-to-digital converter 301 and a digital signal processor 302, which work together to convert the detected optical wave signal into a digital signal and process it to generate a corrected modulation wave signal, thereby providing accurate target information.

[0082] As Figure 4 shown, in an implementable embodiment of the present application, the scanning component 201 includes:

[0083] A laser 401 that generates the modulated laser;

[0084] A beam splitter 402 for splitting the modulated laser into two paths;

[0085] An optical circulator 403 receives one path of the modulated laser and emits the modulated laser along a first output optical path, and a target to be measured for distance is disposed on the first output optical path; the first output optical path is the emission optical path;

[0086] A motor scanning device 404 is disposed on the first output optical path and is located between the target to be measured for distance and the optical circulator, and the motor scanning device is rotatable.

[0087] The laser 401 is a device for distance measurement using laser technology. Its function is to determine the distance between the target object and the laser by emitting laser pulses and measuring the time for the laser to return. The rise of automated and intelligent applications has promoted the application of lasers in fields such as autonomous driving vehicles and drones. The laser is a core component in a lidar system, used to generate laser pulses and send them to the target object, then receive the laser pulses reflected by the target, and calculate the distance between the target object and the lidar by measuring the time difference of the laser pulses. The laser 401 is used to generate modulated laser in this application.

[0088] The beam splitter 402 is an optical device mainly used to split an incident light beam into two or more independent light beams, and is usually used in applications such as optical path splitting, interference, detection, and measurement in optical systems. The beam splitter plays an important role in fields such as optical communication, laser measurement, interference instruments, and optical sensors. The beam splitter 402 is used to split the modulated laser into two paths in this application.

[0089] The optical circulator 403 receives one path of the modulated laser and emits the modulated laser along a first output light beam, and a target to be measured for distance is disposed on the first output light beam.

[0090] An optical circulator (Ring Modulator) 403 is a device for optical modulation, mainly used to mutually modulate two optical signals with different frequencies to generate new optical signals. The optical circulator 403 usually consists of an optical waveguide ring and a modulation device. By introducing a modulation signal into the optical circulator, modulation and frequency modulation of the optical signal can be achieved. The optical circulator 403 has important applications in fields such as optical communication, optical sensing, and optical signal processing. The optical circulator 403 is used to receive one path of the modulated laser and emit the modulated laser along a first output light beam, and a target to be measured for distance is disposed on the first output light beam in this application.

[0091] The motor scanning device 404 is generally installed in the optical system to control the direction and position of optical elements or optical devices. The purpose of installing the motor scanning device between the distance measurement target to be measured and the circulator 403 is to achieve the scanning and orientation of optical signals, or to perform optical imaging or measurement. In this application, the motor scanning device is provided on the first output optical path, and is located between the distance measurement target to be measured and the circulator 403, and the motor scanning device 404 is rotatable.

[0092] As Figure 5 shown, in an implementable embodiment of this application, the receiving component 202 includes:

[0093] A coupler 501, coupled to the second output optical path of the circulator 403 and coupled to the other optical path of the beam splitter 402;

[0094] A detector 502, the incident optical path of the detector 502 is coupled to the output optical path of the coupler 501, and outputs the modulated laser and the reflected laser to the correction component 203.

[0095] The coupler 501 is a device for transmitting an optical signal from one optical waveguide to another optical waveguide. Its function is to effectively transmit the optical signal from one waveguide to another waveguide, and is usually used in fields such as optical devices, optical communication systems, and optical sensors. In this application, the coupler is coupled to the second output line of the circulator and is coupled to the other optical path of the beam splitter.

[0096] The detector 502 is a device for detecting and measuring light, radiation, particles or other physical quantities. Its function is to convert the input signal into a measurable electrical signal, so as to realize the detection, measurement and analysis of the input signal. In this application, the detector is coupled to the output optical path of the coupler, and converts the optical signal of the output optical path of the coupler into a measurable electrical signal.

[0097] In summary, the receiving component 202 includes a coupler 501 and a detector 502, and these components have the advantages of high sensitivity, wide spectral response, low noise, high stability, easy integration, easy adjustment, low power consumption and high reliability.

[0098] The correction component 203 is coupled to the detector 502 and is configured to send the corrected modulation wave signal to the ranging laser to correct the modulation laser generated by the ranging laser. Among them, the correction component 203 is coupled to the detector. The correction component 203 may include optical elements, electronic elements, and a control system, and is used to correct and modulate the signal output by the detector 502. The detector 502 is usually used to detect the received optical signal and convert it into an electrical signal. The correction component 203 processes the electrical signal to achieve signal correction and modulation, and then sends the corrected modulation wave signal to the ranging laser. In addition, the laser 401 usually modulates the laser, that is, a modulation signal is added to the laser signal for subsequent processing and analysis of the laser signal. Different modulation methods can be used for modulation, such as frequency modulation, pulse modulation, etc. In the above background, the correction component 203 is coupled to the detector 502 and is configured to send the corrected modulation wave signal to the laser 401, which can achieve correction and modulation of the modulation laser generated by the laser 401. The correction component 203 can process the signal output by the detector 502 to obtain the required modulation wave signal and send it to the laser 401. After receiving the corrected modulation wave signal, the laser 401 can generate a corresponding modulation laser signal and is used for applications such as ranging and target recognition in the lidar system. Generally speaking, the correction component 203 is coupled to the detector 502 and is used to correct and modulate the modulation laser generated by the laser 401. It is an important part of the lidar system and can achieve precise control and processing of the laser signal, thereby improving the performance and reliability of the lidar system.

[0099] Through this system, the present application can achieve precise distance measurement.

[0100] In an implementable embodiment of the present application, the detector 502 may be a balanced detector.

[0101] A balanced detector is a detector commonly used in optoelectronic detection systems. Compared with unbalanced detectors, it has the following advantages: Strong anti-interference ability: The balanced detector can resist optical and electromagnetic interference in the environment because it has a certain ability to cancel interference signals in the environment. High signal-to-noise ratio: The balanced detector can perform differential operation on the output signals of the two detection units to cancel the noise of the detector itself and improve the quality of the signal. Wide linear range: The balanced detector has good linear response within a certain range and can measure the intensity of the input optical signal more accurately. Suitable for differential measurement: The differential output of the balanced detector can be used for differential measurement, which has great advantages for some applications that require differential signal processing. Generally speaking, the balanced detector has the advantages of strong anti-interference ability, high signal-to-noise ratio, and wide linear range in optoelectronic detection systems, and is suitable for many application scenarios that require high-performance detectors.

[0102] This application further improves the ranging accuracy by using a balanced detector.

[0103] In an implementable embodiment of this application, the system further includes: a collimator, which is disposed on the first outgoing optical path and is located between the circulator and the motor scanner.

[0104] The collimator has the functions of improving the system accuracy and protecting the optical system in the optical system. In this application, the ranging accuracy is further improved by the collimator.

[0105] Figure 6 Schematic diagram of the system structure provided by this application. Refer to Figure 6 , the laser 401 sends the modulated triangular wave signal to the beam splitter 402. This signal carries ranging information. The beam splitter 402 divides this signal into two paths and sends them to the circulator 403 and the coupler 501 respectively. The circulator 403 transmits this signal to the collimator. The collimator ensures the accuracy and stability of the laser beam and transmits the signal to the motor scanning device 404. The motor scanning device 404 drives the laser beam to scan in all directions and corrects the spatial light fixed length at the same time to obtain the distance signal of the target to be measured, and feeds back this distance signal to the circulator 403 through the collimator. The circulator 403 feeds back this distance signal to the coupler 501. The coupler 501 couples out the received signal from the main optical fiber and sends it to the detector 502. The detector 502 converts the received signal into an electrical signal and sends it to the analog-to-digital converter 301. The analog-to-digital converter 301 converts the electrical signal into a digital signal and sends it to the digital signal processor 302. The digital signal processor 302 processes and analyzes this digital signal, extracts the distance value of the target to be measured according to the above ranging method, compensates and corrects the error, generates a corrected triangular wave signal and sends it to the laser 401. The laser 401 performs waveform modulation according to this corrected triangular wave signal to improve the accuracy and stability of the ranging system.

[0106] Figure 7 Schematic diagram of the flow of a linear correction method based on Doppler compensation provided by an embodiment of this application. For the sake of simplicity, only the parts related to the embodiment of this application are shown.

[0107] S701, obtain the initial corrected triangular wave of the laser and the original intermediate frequency signal data of the target to be measured;

[0108] S702, convert the original intermediate frequency signal to the complex domain to obtain the intermediate frequency signal in the complex domain;

[0109] S703, generate a linear correction parameter according to the intermediate frequency signal in the complex domain to correct the laser.

[0110] Exemplarily, assume that the calibration of the lidar system is in progress and the operations are carried out according to the steps described above:

[0111] First, obtain the raw data from the laser and the target to be measured. This includes the laser pulse signal emitted by the laser and the signal reflected from the target. Next, convert the raw intermediate-frequency signal reflected from the target into a complex-domain intermediate-frequency signal. This is achieved through some signal processing algorithms and digital signal processing techniques, such as the fast Fourier transform (FFT), etc. Based on the complex-domain intermediate-frequency signal, perform signal processing and calculations to generate the parameters for linearly calibrating the laser. This involves analyzing and calculating aspects such as the frequency, amplitude, and phase of the signal to generate appropriate calibration parameters.

[0112] Specifically, first, download the initial calibration triangular wave in the first step; then, the ADC acquires the intermediate-frequency signal data {a1, a2, a3, ……, a n}. Next, perform the Hilbert transform on the intermediate-frequency signal data to transform the data into the complex domain: {a1 + b 1*j , a2 + b 2*j , a3 + b 3*j , ……, a n + b n*j}, where a represents the real part and b represents the imaginary part.

[0113] Perform phase calculation based on the Hilbert transform complex-domain ADC data to obtain the phase sequence

[0114] Phase_i = a i + b i*j / (a (i-1) + b (i-1)*j )

[0115] {phase_1, phase_2, phase_3, ……, phase_N}

[0116] Then, according to the sampling frequency FSP, obtain the interval time t of the sampling points, and calculate the time-frequency curve of the intermediate-frequency data freq_i = phase_i / t. Finally, perform fluctuation analysis on the obtained time-frequency sequence freq_i. If the standard deviation requirement is met, it is okay; if not, adjust the calibration parameters according to the characteristics of the time-frequency curve.

[0117] Using the known length of the delay optical fiber, calculate the frequency of the acquired intermediate-frequency signal according to the laser modulation period and modulation bandwidth, and convert it into distance. The distance-frequency point equivalence formula is as follows:

[0118]

[0119] where R is the ranging value, B is the modulation bandwidth, C is the light flight speed, and T is the modulation period length.

[0120] Specific current preconditions: modulation period 100KHz, modulation bandwidth 2GHz. Frequency points at a distance of 30m

[0121]

[0122] The above process involves the conversion from raw data to an intermediate-frequency signal in the complex domain, and generating parameters for linear correction of the laser based on the intermediate-frequency signal in the complex domain. The entire correction process helps the lidar system measure the target distance information more accurately.

[0123] In an implementable embodiment of the present application, the conversion of the original intermediate-frequency signal to the complex domain to obtain an intermediate-frequency signal in the complex domain includes:

[0124] Performing a Hilbert transform on the original intermediate-frequency signal data to convert the original intermediate-frequency signal to the complex domain and obtain an intermediate-frequency signal in the complex domain.

[0125] Exemplarily, assume there is a segment of original intermediate-frequency signal data, which is converted to an intermediate-frequency signal in the complex domain for further signal processing and analysis. Operate according to the steps described above:

[0126] First, perform a Hilbert transform on the original intermediate-frequency signal data. The Hilbert transform is a commonly used signal processing technique that can convert a real-domain signal to a complex-domain signal. The implementation of the Hilbert transform can use digital signal processing algorithms such as the fast Fourier transform (FFT), etc.

[0127] After the Hilbert transform, a complex-domain representation of the original intermediate-frequency signal is obtained. This intermediate-frequency signal in the complex domain contains the amplitude and phase information of the original signal and can be used for further signal processing and analysis.

[0128] Next, perform various signal processing and calculations on the intermediate-frequency signal in the complex domain, such as filtering, frequency-domain analysis, phase demodulation, etc. The above processing and calculations can extract useful information in the signal, such as the distance, speed, direction, etc. of the target.

[0129] Generally speaking, this process involves converting the original intermediate-frequency signal to an intermediate-frequency signal in the complex domain for further signal processing and analysis. The Hilbert transform is a key step in it, which can convert a real-domain signal to a complex-domain signal, thereby containing more information.

[0130] As Figure 8 shown, in an implementable embodiment of the present application, the generation of linear correction parameters based on the intermediate-frequency signal in the complex domain includes:

[0131] S801, performing a phase calculation on the intermediate-frequency signal in the complex domain to obtain a phase sequence;

[0132] S802. Calculate the time-frequency curve of the intermediate-frequency data according to the sampling frequency and the phase sequence.

[0133] S803. Conduct a fluctuation analysis on the time-frequency curve. If the fluctuation amount is lower than a preset standard deviation, the correction parameter is the parameter of the initial correction triangular wave.

[0134] S804. If the volatility is higher than the standard deviation, update the correction parameter according to the characteristics of the time-frequency curve.

[0135] Exemplarily, assume there is a lidar system that emits laser pulses and receives echo signals. The intermediate-frequency signal data {a1, a2, a3, ……, a n} is acquired using an ADC.

[0136] First, calculate the phase of the intermediate-frequency signal in the complex domain to obtain the phase sequence. Assume the intermediate-frequency signal data in the complex domain is {a1 + b 1j , a2 + b 2j , a3 + b 3j , ……, a n + b nj}. Calculate the phase sequence Phase_i = atan(b i / a i ). Thus, we obtain the phase sequence.

[0137] Then, calculate the time-frequency curve of the intermediate-frequency data according to the sampling frequency and the phase sequence. Assume the sampling frequency is FSP, obtain the interval time t of the sampling points, and then calculate the time-frequency curve freq_i = Phase_i / t of the intermediate-frequency data using this interval time. Thus, a sequence of time-frequency curves is obtained.

[0138] Next, conduct a fluctuation analysis on the time-frequency curve. If the fluctuation amount is lower than a preset standard deviation, the correction parameter is the parameter of the initial correction triangular wave. Assume the standard deviation of the time-frequency curve is calculated. If the standard deviation is lower than a preset threshold, it indicates that the fluctuation is small, and the correction parameter is set to the parameter of the initial correction triangular wave.

[0139] Finally, if the volatility is higher than the standard deviation, update the correction parameter according to the characteristics of the time-frequency curve. If the standard deviation is higher than a preset threshold, it indicates that the fluctuation is large. Update the correction parameter according to the characteristics of the time-frequency curve, such as the variation law of the frequency, the variation law of the phase, etc., so that the fluctuation of the time-frequency curve meets the requirements.

[0140] This processing flow deeply analyzes the intermediate-frequency signal of the lidar system and adjusts the parameters according to the analysis results to obtain more accurate information such as distance and speed.

[0141] As Figure 9 shown, in an implementable embodiment of the present application, updating the correction parameter according to the characteristics of the time-frequency curve includes:

[0142] S901, analyze the characteristics of the time-frequency curve to generate a Doppler frequency shift result;

[0143] S902, update the correction parameter according to the Doppler frequency shift result.

[0144] Exemplarily, assume there is a radar system that detects the movement of a target object by transmitting and receiving signals. A lidar is used to measure the distance and speed of the target object. During this process, intermediate-frequency data signals are collected and subjected to time-frequency analysis to obtain a time-frequency curve.

[0145] Now assume that the time-frequency curve is analyzed and it is found that it contains the Doppler frequency shift information of the target object. The Doppler frequency shift is the frequency change caused by the movement of the target object. By analyzing the characteristics of the time-frequency curve, the Doppler frequency shift result of the target object can be obtained.

[0146] Specifically, assume that through time-frequency analysis, the Doppler frequency shift of the target object is found to be f_d, and this frequency shift can reflect the speed information of the target object. Now it is necessary to update the correction parameter according to this Doppler frequency shift result. For example, the transmission frequency or reception frequency of the radar system can be adjusted so that the received signal can more accurately reflect the speed information of the target object.

[0147] By analyzing the characteristics of the time-frequency curve, extracting the Doppler frequency shift result, and then updating the correction parameter according to this result, the speed information of the target object can be obtained more accurately, thereby improving the ranging performance and accuracy of the radar system.

[0148] Figure 10 FIG. is a schematic structural diagram of a terminal device provided by an embodiment of the present application. The terminal device 1000 includes: at least one processor 1001( Figure 10 only one is shown in the figure), a processor, a memory 1002, and a computer program 1003 stored in the memory 1002 and executable on the at least one processor 1001. When the processor 1001 executes the computer program 1003, the steps in the embodiment of the above-mentioned river rainfall water quality compliance auxiliary processing method are implemented.

[0149] The terminal device 1000 may be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The terminal device may include, but is not limited to, a processor 1001 and a memory 1002. Those skilled in the art can understand, Figure 10The terminal device 1000 is merely an example and does not limit the terminal device 1000. It may include more or fewer components than shown in the figure, or combine certain components, or different components. For example, it may also include input / output devices, network access devices, etc.

[0150] The so-called processor 1001 may be a central processing unit (CPU). The processor 1001 may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0151] In some embodiments, the memory 1002 may be an internal storage unit of the terminal device 1000, such as the hard disk or memory of the terminal device 1000. In other embodiments, the memory 1002 may also be an external storage device of the terminal device 1000, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc., equipped on the terminal device 1000. Further, the memory 1002 may also include both the internal storage unit and the external storage device of the terminal device 1000. The memory 1002 is used to store an operating system, application programs, a boot loader, data, and other programs, such as the program code of the computer program, etc. The memory 1002 may also be used to temporarily store data that has been output or will be output.

[0152] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above division of each functional unit and module is used as an example. In actual applications, the above functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiments can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of this application. The specific working processes of the units and modules in the above system can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0153] In the above embodiments, the descriptions of the respective embodiments have their own emphases. If there is no detailed description or record of a certain part in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0154] The embodiments of the present application further provide a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps in the foregoing method embodiments can be implemented.

[0155] The embodiments of the present application provide a computer program product. When the computer program product runs on a mobile terminal, the mobile terminal can be enabled to implement the steps in the foregoing method embodiments when executed.

[0156] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, to implement all or part of the processes in the above-mentioned embodiment methods of this application, a computer program can be used to instruct relevant hardware to complete. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above-mentioned various method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form, etc. The computer-readable medium can at least include: any entity or device that can carry the computer program code to the photographing device / terminal device, recording medium, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal, and software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk, or an optical disc, etc. In some jurisdictions, according to legislation and patent practice, the computer-readable medium cannot be an electrical carrier signal and a telecommunication signal.

[0157] In the above embodiments, the descriptions of the various embodiments have their own focuses. For the parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0158] Those of ordinary skill in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0159] In the embodiments provided in this application, it should be understood that the disclosed device / network device and method can be implemented in other ways. For example, the device / network device embodiments described above are only illustrative. For example, the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some interfaces. The indirect coupling or communication connection of the device or unit can be in an electrical, mechanical or other form.

[0160] The unit described as a separation component may or may not be physically separated. The component shown as a unit may or may not be a physical unit, that is, it may be located in one place or may be distributed over multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0161] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A linear correction system based on Doppler compensation, characterized in that, Including: A scanning component, including a laser, which is used to irradiate the modulated laser emitted by the laser to a target to be measured through an emission optical path; A receiving component, which is used to receive the modulated laser generated by the laser and the reflected laser reflected by the target to be measured; A calibration component, coupled to the receiving component and the scanning component, which is used to obtain a calibration laser according to the modulated laser and the reflected laser to calibrate the modulated laser of the scanning component; wherein, the calibration component is specifically used to perform analog-to-digital conversion on the modulated laser and the reflected laser to obtain an initial calibration triangular wave and the original intermediate frequency signal data of the target to be measured, and then convert the original intermediate frequency signal to the complex domain to obtain a complex-domain intermediate frequency signal; finally, generate a linear calibration parameter according to the complex-domain intermediate frequency signal to calibrate the laser.

2. The system according to claim 1, wherein The calibration component includes an analog-to-digital converter and a digital signal processor. The analog-to-digital converter is coupled to a detector and is used to convert the modulated laser and the reflected laser into digital signals; The digital signal processor is used to generate the calibration laser according to the digital signals.

3. The system according to claim 1, wherein The scanning component includes: A laser, which generates the modulated laser; A beam splitter, which is used to divide the modulated laser into two paths; A circulator, which receives one path of the modulated laser and emits the modulated laser through a first emission optical path, and a target to be ranged is arranged on the first emission optical path; the first emission optical path is the emission optical path; A motor scanning device, which is arranged on the first emission optical path and is located between the target to be ranged and the circulator, and the motor scanning device is rotatable.

4. The system according to claim 1, characterized in that, The receiving component includes: A coupler, which is coupled to the second emission optical path of the circulator and is coupled to the other optical path of the beam splitter; A detector, the incident optical path of the detector is coupled to the output optical path of the coupler, and outputs the modulated laser and the reflected laser to the calibration component.

5. The system according to claim 1, characterized in that, The system further includes: a collimator, which is arranged on the first emission optical path and is located between the circulator and the motor scanner.

6. A linear correction method using the system according to any one of claims 1-5, characterized in that, The method includes: Obtaining the initial calibration triangular wave of the laser and the original intermediate frequency signal data of the target to be measured; Converting the original intermediate frequency signal to the complex domain to obtain a complex-domain intermediate frequency signal; Generating a linear calibration parameter according to the complex-domain intermediate frequency signal to calibrate the laser.

7. The method according to claim 6, characterized in that, The converting the original intermediate frequency signal to the complex domain to obtain a complex-domain intermediate frequency signal includes: Performing a Hilbert transform on the original intermediate frequency signal data to convert the original intermediate frequency signal to the complex domain to obtain a complex-domain intermediate frequency signal.

8. The method according to claim 6, characterized in that, The generating a linear calibration parameter according to the complex-domain intermediate frequency signal includes: Performing a phase calculation on the complex-domain intermediate frequency signal to obtain a phase sequence; Calculating the time-frequency curve of the intermediate frequency data according to the sampling frequency and the phase sequence; Performing a fluctuation analysis on the time-frequency curve. If the fluctuation amount is lower than a preset standard deviation, the calibration parameter is the parameter of the initial calibration triangular wave; If the fluctuation rate is higher than the standard deviation, update the calibration parameter according to the characteristics of the time-frequency curve.

9. The method according to claim 8, wherein The updating the calibration parameter according to the characteristics of the time-frequency curve includes: Analyze the characteristics of the time-frequency curve to generate a Doppler frequency shift result; Update the correction parameter according to the Doppler frequency shift result.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method according to any one of claims 6 to 9.

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